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linux-zen-server/tools/lib/bpf/libbpf.c

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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/*
* Common eBPF ELF object loading operations.
*
* Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
* Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
* Copyright (C) 2015 Huawei Inc.
* Copyright (C) 2017 Nicira, Inc.
* Copyright (C) 2019 Isovalent, Inc.
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <libgen.h>
#include <inttypes.h>
#include <limits.h>
#include <string.h>
#include <unistd.h>
#include <endian.h>
#include <fcntl.h>
#include <errno.h>
#include <ctype.h>
#include <asm/unistd.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/filter.h>
#include <linux/limits.h>
#include <linux/perf_event.h>
#include <linux/ring_buffer.h>
#include <sys/epoll.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/vfs.h>
#include <sys/utsname.h>
#include <sys/resource.h>
#include <libelf.h>
#include <gelf.h>
#include <zlib.h>
#include "libbpf.h"
#include "bpf.h"
#include "btf.h"
#include "str_error.h"
#include "libbpf_internal.h"
#include "hashmap.h"
#include "bpf_gen_internal.h"
#ifndef BPF_FS_MAGIC
#define BPF_FS_MAGIC 0xcafe4a11
#endif
#define BPF_INSN_SZ (sizeof(struct bpf_insn))
/* vsprintf() in __base_pr() uses nonliteral format string. It may break
* compilation if user enables corresponding warning. Disable it explicitly.
*/
#pragma GCC diagnostic ignored "-Wformat-nonliteral"
#define __printf(a, b) __attribute__((format(printf, a, b)))
static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
static const char * const attach_type_name[] = {
[BPF_CGROUP_INET_INGRESS] = "cgroup_inet_ingress",
[BPF_CGROUP_INET_EGRESS] = "cgroup_inet_egress",
[BPF_CGROUP_INET_SOCK_CREATE] = "cgroup_inet_sock_create",
[BPF_CGROUP_INET_SOCK_RELEASE] = "cgroup_inet_sock_release",
[BPF_CGROUP_SOCK_OPS] = "cgroup_sock_ops",
[BPF_CGROUP_DEVICE] = "cgroup_device",
[BPF_CGROUP_INET4_BIND] = "cgroup_inet4_bind",
[BPF_CGROUP_INET6_BIND] = "cgroup_inet6_bind",
[BPF_CGROUP_INET4_CONNECT] = "cgroup_inet4_connect",
[BPF_CGROUP_INET6_CONNECT] = "cgroup_inet6_connect",
[BPF_CGROUP_INET4_POST_BIND] = "cgroup_inet4_post_bind",
[BPF_CGROUP_INET6_POST_BIND] = "cgroup_inet6_post_bind",
[BPF_CGROUP_INET4_GETPEERNAME] = "cgroup_inet4_getpeername",
[BPF_CGROUP_INET6_GETPEERNAME] = "cgroup_inet6_getpeername",
[BPF_CGROUP_INET4_GETSOCKNAME] = "cgroup_inet4_getsockname",
[BPF_CGROUP_INET6_GETSOCKNAME] = "cgroup_inet6_getsockname",
[BPF_CGROUP_UDP4_SENDMSG] = "cgroup_udp4_sendmsg",
[BPF_CGROUP_UDP6_SENDMSG] = "cgroup_udp6_sendmsg",
[BPF_CGROUP_SYSCTL] = "cgroup_sysctl",
[BPF_CGROUP_UDP4_RECVMSG] = "cgroup_udp4_recvmsg",
[BPF_CGROUP_UDP6_RECVMSG] = "cgroup_udp6_recvmsg",
[BPF_CGROUP_GETSOCKOPT] = "cgroup_getsockopt",
[BPF_CGROUP_SETSOCKOPT] = "cgroup_setsockopt",
[BPF_SK_SKB_STREAM_PARSER] = "sk_skb_stream_parser",
[BPF_SK_SKB_STREAM_VERDICT] = "sk_skb_stream_verdict",
[BPF_SK_SKB_VERDICT] = "sk_skb_verdict",
[BPF_SK_MSG_VERDICT] = "sk_msg_verdict",
[BPF_LIRC_MODE2] = "lirc_mode2",
[BPF_FLOW_DISSECTOR] = "flow_dissector",
[BPF_TRACE_RAW_TP] = "trace_raw_tp",
[BPF_TRACE_FENTRY] = "trace_fentry",
[BPF_TRACE_FEXIT] = "trace_fexit",
[BPF_MODIFY_RETURN] = "modify_return",
[BPF_LSM_MAC] = "lsm_mac",
[BPF_LSM_CGROUP] = "lsm_cgroup",
[BPF_SK_LOOKUP] = "sk_lookup",
[BPF_TRACE_ITER] = "trace_iter",
[BPF_XDP_DEVMAP] = "xdp_devmap",
[BPF_XDP_CPUMAP] = "xdp_cpumap",
[BPF_XDP] = "xdp",
[BPF_SK_REUSEPORT_SELECT] = "sk_reuseport_select",
[BPF_SK_REUSEPORT_SELECT_OR_MIGRATE] = "sk_reuseport_select_or_migrate",
[BPF_PERF_EVENT] = "perf_event",
[BPF_TRACE_KPROBE_MULTI] = "trace_kprobe_multi",
};
static const char * const link_type_name[] = {
[BPF_LINK_TYPE_UNSPEC] = "unspec",
[BPF_LINK_TYPE_RAW_TRACEPOINT] = "raw_tracepoint",
[BPF_LINK_TYPE_TRACING] = "tracing",
[BPF_LINK_TYPE_CGROUP] = "cgroup",
[BPF_LINK_TYPE_ITER] = "iter",
[BPF_LINK_TYPE_NETNS] = "netns",
[BPF_LINK_TYPE_XDP] = "xdp",
[BPF_LINK_TYPE_PERF_EVENT] = "perf_event",
[BPF_LINK_TYPE_KPROBE_MULTI] = "kprobe_multi",
[BPF_LINK_TYPE_STRUCT_OPS] = "struct_ops",
};
static const char * const map_type_name[] = {
[BPF_MAP_TYPE_UNSPEC] = "unspec",
[BPF_MAP_TYPE_HASH] = "hash",
[BPF_MAP_TYPE_ARRAY] = "array",
[BPF_MAP_TYPE_PROG_ARRAY] = "prog_array",
[BPF_MAP_TYPE_PERF_EVENT_ARRAY] = "perf_event_array",
[BPF_MAP_TYPE_PERCPU_HASH] = "percpu_hash",
[BPF_MAP_TYPE_PERCPU_ARRAY] = "percpu_array",
[BPF_MAP_TYPE_STACK_TRACE] = "stack_trace",
[BPF_MAP_TYPE_CGROUP_ARRAY] = "cgroup_array",
[BPF_MAP_TYPE_LRU_HASH] = "lru_hash",
[BPF_MAP_TYPE_LRU_PERCPU_HASH] = "lru_percpu_hash",
[BPF_MAP_TYPE_LPM_TRIE] = "lpm_trie",
[BPF_MAP_TYPE_ARRAY_OF_MAPS] = "array_of_maps",
[BPF_MAP_TYPE_HASH_OF_MAPS] = "hash_of_maps",
[BPF_MAP_TYPE_DEVMAP] = "devmap",
[BPF_MAP_TYPE_DEVMAP_HASH] = "devmap_hash",
[BPF_MAP_TYPE_SOCKMAP] = "sockmap",
[BPF_MAP_TYPE_CPUMAP] = "cpumap",
[BPF_MAP_TYPE_XSKMAP] = "xskmap",
[BPF_MAP_TYPE_SOCKHASH] = "sockhash",
[BPF_MAP_TYPE_CGROUP_STORAGE] = "cgroup_storage",
[BPF_MAP_TYPE_REUSEPORT_SOCKARRAY] = "reuseport_sockarray",
[BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE] = "percpu_cgroup_storage",
[BPF_MAP_TYPE_QUEUE] = "queue",
[BPF_MAP_TYPE_STACK] = "stack",
[BPF_MAP_TYPE_SK_STORAGE] = "sk_storage",
[BPF_MAP_TYPE_STRUCT_OPS] = "struct_ops",
[BPF_MAP_TYPE_RINGBUF] = "ringbuf",
[BPF_MAP_TYPE_INODE_STORAGE] = "inode_storage",
[BPF_MAP_TYPE_TASK_STORAGE] = "task_storage",
[BPF_MAP_TYPE_BLOOM_FILTER] = "bloom_filter",
[BPF_MAP_TYPE_USER_RINGBUF] = "user_ringbuf",
[BPF_MAP_TYPE_CGRP_STORAGE] = "cgrp_storage",
};
static const char * const prog_type_name[] = {
[BPF_PROG_TYPE_UNSPEC] = "unspec",
[BPF_PROG_TYPE_SOCKET_FILTER] = "socket_filter",
[BPF_PROG_TYPE_KPROBE] = "kprobe",
[BPF_PROG_TYPE_SCHED_CLS] = "sched_cls",
[BPF_PROG_TYPE_SCHED_ACT] = "sched_act",
[BPF_PROG_TYPE_TRACEPOINT] = "tracepoint",
[BPF_PROG_TYPE_XDP] = "xdp",
[BPF_PROG_TYPE_PERF_EVENT] = "perf_event",
[BPF_PROG_TYPE_CGROUP_SKB] = "cgroup_skb",
[BPF_PROG_TYPE_CGROUP_SOCK] = "cgroup_sock",
[BPF_PROG_TYPE_LWT_IN] = "lwt_in",
[BPF_PROG_TYPE_LWT_OUT] = "lwt_out",
[BPF_PROG_TYPE_LWT_XMIT] = "lwt_xmit",
[BPF_PROG_TYPE_SOCK_OPS] = "sock_ops",
[BPF_PROG_TYPE_SK_SKB] = "sk_skb",
[BPF_PROG_TYPE_CGROUP_DEVICE] = "cgroup_device",
[BPF_PROG_TYPE_SK_MSG] = "sk_msg",
[BPF_PROG_TYPE_RAW_TRACEPOINT] = "raw_tracepoint",
[BPF_PROG_TYPE_CGROUP_SOCK_ADDR] = "cgroup_sock_addr",
[BPF_PROG_TYPE_LWT_SEG6LOCAL] = "lwt_seg6local",
[BPF_PROG_TYPE_LIRC_MODE2] = "lirc_mode2",
[BPF_PROG_TYPE_SK_REUSEPORT] = "sk_reuseport",
[BPF_PROG_TYPE_FLOW_DISSECTOR] = "flow_dissector",
[BPF_PROG_TYPE_CGROUP_SYSCTL] = "cgroup_sysctl",
[BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE] = "raw_tracepoint_writable",
[BPF_PROG_TYPE_CGROUP_SOCKOPT] = "cgroup_sockopt",
[BPF_PROG_TYPE_TRACING] = "tracing",
[BPF_PROG_TYPE_STRUCT_OPS] = "struct_ops",
[BPF_PROG_TYPE_EXT] = "ext",
[BPF_PROG_TYPE_LSM] = "lsm",
[BPF_PROG_TYPE_SK_LOOKUP] = "sk_lookup",
[BPF_PROG_TYPE_SYSCALL] = "syscall",
};
static int __base_pr(enum libbpf_print_level level, const char *format,
va_list args)
{
if (level == LIBBPF_DEBUG)
return 0;
return vfprintf(stderr, format, args);
}
static libbpf_print_fn_t __libbpf_pr = __base_pr;
libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn)
{
libbpf_print_fn_t old_print_fn = __libbpf_pr;
__libbpf_pr = fn;
return old_print_fn;
}
__printf(2, 3)
void libbpf_print(enum libbpf_print_level level, const char *format, ...)
{
va_list args;
int old_errno;
if (!__libbpf_pr)
return;
old_errno = errno;
va_start(args, format);
__libbpf_pr(level, format, args);
va_end(args);
errno = old_errno;
}
static void pr_perm_msg(int err)
{
struct rlimit limit;
char buf[100];
if (err != -EPERM || geteuid() != 0)
return;
err = getrlimit(RLIMIT_MEMLOCK, &limit);
if (err)
return;
if (limit.rlim_cur == RLIM_INFINITY)
return;
if (limit.rlim_cur < 1024)
snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur);
else if (limit.rlim_cur < 1024*1024)
snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024);
else
snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024));
pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n",
buf);
}
#define STRERR_BUFSIZE 128
/* Copied from tools/perf/util/util.h */
#ifndef zfree
# define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
#endif
#ifndef zclose
# define zclose(fd) ({ \
int ___err = 0; \
if ((fd) >= 0) \
___err = close((fd)); \
fd = -1; \
___err; })
#endif
static inline __u64 ptr_to_u64(const void *ptr)
{
return (__u64) (unsigned long) ptr;
}
int libbpf_set_strict_mode(enum libbpf_strict_mode mode)
{
/* as of v1.0 libbpf_set_strict_mode() is a no-op */
return 0;
}
__u32 libbpf_major_version(void)
{
return LIBBPF_MAJOR_VERSION;
}
__u32 libbpf_minor_version(void)
{
return LIBBPF_MINOR_VERSION;
}
const char *libbpf_version_string(void)
{
#define __S(X) #X
#define _S(X) __S(X)
return "v" _S(LIBBPF_MAJOR_VERSION) "." _S(LIBBPF_MINOR_VERSION);
#undef _S
#undef __S
}
enum reloc_type {
RELO_LD64,
RELO_CALL,
RELO_DATA,
RELO_EXTERN_VAR,
RELO_EXTERN_FUNC,
RELO_SUBPROG_ADDR,
RELO_CORE,
};
struct reloc_desc {
enum reloc_type type;
int insn_idx;
union {
const struct bpf_core_relo *core_relo; /* used when type == RELO_CORE */
struct {
int map_idx;
int sym_off;
};
};
};
/* stored as sec_def->cookie for all libbpf-supported SEC()s */
enum sec_def_flags {
SEC_NONE = 0,
/* expected_attach_type is optional, if kernel doesn't support that */
SEC_EXP_ATTACH_OPT = 1,
/* legacy, only used by libbpf_get_type_names() and
* libbpf_attach_type_by_name(), not used by libbpf itself at all.
* This used to be associated with cgroup (and few other) BPF programs
* that were attachable through BPF_PROG_ATTACH command. Pretty
* meaningless nowadays, though.
*/
SEC_ATTACHABLE = 2,
SEC_ATTACHABLE_OPT = SEC_ATTACHABLE | SEC_EXP_ATTACH_OPT,
/* attachment target is specified through BTF ID in either kernel or
* other BPF program's BTF object
*/
SEC_ATTACH_BTF = 4,
/* BPF program type allows sleeping/blocking in kernel */
SEC_SLEEPABLE = 8,
/* BPF program support non-linear XDP buffer */
SEC_XDP_FRAGS = 16,
};
struct bpf_sec_def {
char *sec;
enum bpf_prog_type prog_type;
enum bpf_attach_type expected_attach_type;
long cookie;
int handler_id;
libbpf_prog_setup_fn_t prog_setup_fn;
libbpf_prog_prepare_load_fn_t prog_prepare_load_fn;
libbpf_prog_attach_fn_t prog_attach_fn;
};
/*
* bpf_prog should be a better name but it has been used in
* linux/filter.h.
*/
struct bpf_program {
char *name;
char *sec_name;
size_t sec_idx;
const struct bpf_sec_def *sec_def;
/* this program's instruction offset (in number of instructions)
* within its containing ELF section
*/
size_t sec_insn_off;
/* number of original instructions in ELF section belonging to this
* program, not taking into account subprogram instructions possible
* appended later during relocation
*/
size_t sec_insn_cnt;
/* Offset (in number of instructions) of the start of instruction
* belonging to this BPF program within its containing main BPF
* program. For the entry-point (main) BPF program, this is always
* zero. For a sub-program, this gets reset before each of main BPF
* programs are processed and relocated and is used to determined
* whether sub-program was already appended to the main program, and
* if yes, at which instruction offset.
*/
size_t sub_insn_off;
/* instructions that belong to BPF program; insns[0] is located at
* sec_insn_off instruction within its ELF section in ELF file, so
* when mapping ELF file instruction index to the local instruction,
* one needs to subtract sec_insn_off; and vice versa.
*/
struct bpf_insn *insns;
/* actual number of instruction in this BPF program's image; for
* entry-point BPF programs this includes the size of main program
* itself plus all the used sub-programs, appended at the end
*/
size_t insns_cnt;
struct reloc_desc *reloc_desc;
int nr_reloc;
/* BPF verifier log settings */
char *log_buf;
size_t log_size;
__u32 log_level;
struct bpf_object *obj;
int fd;
bool autoload;
bool autoattach;
bool mark_btf_static;
enum bpf_prog_type type;
enum bpf_attach_type expected_attach_type;
int prog_ifindex;
__u32 attach_btf_obj_fd;
__u32 attach_btf_id;
__u32 attach_prog_fd;
void *func_info;
__u32 func_info_rec_size;
__u32 func_info_cnt;
void *line_info;
__u32 line_info_rec_size;
__u32 line_info_cnt;
__u32 prog_flags;
};
struct bpf_struct_ops {
const char *tname;
const struct btf_type *type;
struct bpf_program **progs;
__u32 *kern_func_off;
/* e.g. struct tcp_congestion_ops in bpf_prog's btf format */
void *data;
/* e.g. struct bpf_struct_ops_tcp_congestion_ops in
* btf_vmlinux's format.
* struct bpf_struct_ops_tcp_congestion_ops {
* [... some other kernel fields ...]
* struct tcp_congestion_ops data;
* }
* kern_vdata-size == sizeof(struct bpf_struct_ops_tcp_congestion_ops)
* bpf_map__init_kern_struct_ops() will populate the "kern_vdata"
* from "data".
*/
void *kern_vdata;
__u32 type_id;
};
#define DATA_SEC ".data"
#define BSS_SEC ".bss"
#define RODATA_SEC ".rodata"
#define KCONFIG_SEC ".kconfig"
#define KSYMS_SEC ".ksyms"
#define STRUCT_OPS_SEC ".struct_ops"
enum libbpf_map_type {
LIBBPF_MAP_UNSPEC,
LIBBPF_MAP_DATA,
LIBBPF_MAP_BSS,
LIBBPF_MAP_RODATA,
LIBBPF_MAP_KCONFIG,
};
struct bpf_map_def {
unsigned int type;
unsigned int key_size;
unsigned int value_size;
unsigned int max_entries;
unsigned int map_flags;
};
struct bpf_map {
struct bpf_object *obj;
char *name;
/* real_name is defined for special internal maps (.rodata*,
* .data*, .bss, .kconfig) and preserves their original ELF section
* name. This is important to be able to find corresponding BTF
* DATASEC information.
*/
char *real_name;
int fd;
int sec_idx;
size_t sec_offset;
int map_ifindex;
int inner_map_fd;
struct bpf_map_def def;
__u32 numa_node;
__u32 btf_var_idx;
__u32 btf_key_type_id;
__u32 btf_value_type_id;
__u32 btf_vmlinux_value_type_id;
enum libbpf_map_type libbpf_type;
void *mmaped;
struct bpf_struct_ops *st_ops;
struct bpf_map *inner_map;
void **init_slots;
int init_slots_sz;
char *pin_path;
bool pinned;
bool reused;
bool autocreate;
__u64 map_extra;
};
enum extern_type {
EXT_UNKNOWN,
EXT_KCFG,
EXT_KSYM,
};
enum kcfg_type {
KCFG_UNKNOWN,
KCFG_CHAR,
KCFG_BOOL,
KCFG_INT,
KCFG_TRISTATE,
KCFG_CHAR_ARR,
};
struct extern_desc {
enum extern_type type;
int sym_idx;
int btf_id;
int sec_btf_id;
const char *name;
bool is_set;
bool is_weak;
union {
struct {
enum kcfg_type type;
int sz;
int align;
int data_off;
bool is_signed;
} kcfg;
struct {
unsigned long long addr;
/* target btf_id of the corresponding kernel var. */
int kernel_btf_obj_fd;
int kernel_btf_id;
/* local btf_id of the ksym extern's type. */
__u32 type_id;
/* BTF fd index to be patched in for insn->off, this is
* 0 for vmlinux BTF, index in obj->fd_array for module
* BTF
*/
__s16 btf_fd_idx;
} ksym;
};
};
struct module_btf {
struct btf *btf;
char *name;
__u32 id;
int fd;
int fd_array_idx;
};
enum sec_type {
SEC_UNUSED = 0,
SEC_RELO,
SEC_BSS,
SEC_DATA,
SEC_RODATA,
};
struct elf_sec_desc {
enum sec_type sec_type;
Elf64_Shdr *shdr;
Elf_Data *data;
};
struct elf_state {
int fd;
const void *obj_buf;
size_t obj_buf_sz;
Elf *elf;
Elf64_Ehdr *ehdr;
Elf_Data *symbols;
Elf_Data *st_ops_data;
size_t shstrndx; /* section index for section name strings */
size_t strtabidx;
struct elf_sec_desc *secs;
size_t sec_cnt;
int btf_maps_shndx;
__u32 btf_maps_sec_btf_id;
int text_shndx;
int symbols_shndx;
int st_ops_shndx;
};
struct usdt_manager;
struct bpf_object {
char name[BPF_OBJ_NAME_LEN];
char license[64];
__u32 kern_version;
struct bpf_program *programs;
size_t nr_programs;
struct bpf_map *maps;
size_t nr_maps;
size_t maps_cap;
char *kconfig;
struct extern_desc *externs;
int nr_extern;
int kconfig_map_idx;
bool loaded;
bool has_subcalls;
bool has_rodata;
struct bpf_gen *gen_loader;
/* Information when doing ELF related work. Only valid if efile.elf is not NULL */
struct elf_state efile;
struct btf *btf;
struct btf_ext *btf_ext;
/* Parse and load BTF vmlinux if any of the programs in the object need
* it at load time.
*/
struct btf *btf_vmlinux;
/* Path to the custom BTF to be used for BPF CO-RE relocations as an
* override for vmlinux BTF.
*/
char *btf_custom_path;
/* vmlinux BTF override for CO-RE relocations */
struct btf *btf_vmlinux_override;
/* Lazily initialized kernel module BTFs */
struct module_btf *btf_modules;
bool btf_modules_loaded;
size_t btf_module_cnt;
size_t btf_module_cap;
/* optional log settings passed to BPF_BTF_LOAD and BPF_PROG_LOAD commands */
char *log_buf;
size_t log_size;
__u32 log_level;
int *fd_array;
size_t fd_array_cap;
size_t fd_array_cnt;
struct usdt_manager *usdt_man;
char path[];
};
static const char *elf_sym_str(const struct bpf_object *obj, size_t off);
static const char *elf_sec_str(const struct bpf_object *obj, size_t off);
static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx);
static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name);
static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn);
static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn);
static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn);
static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx);
static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx);
void bpf_program__unload(struct bpf_program *prog)
{
if (!prog)
return;
zclose(prog->fd);
zfree(&prog->func_info);
zfree(&prog->line_info);
}
static void bpf_program__exit(struct bpf_program *prog)
{
if (!prog)
return;
bpf_program__unload(prog);
zfree(&prog->name);
zfree(&prog->sec_name);
zfree(&prog->insns);
zfree(&prog->reloc_desc);
prog->nr_reloc = 0;
prog->insns_cnt = 0;
prog->sec_idx = -1;
}
static bool insn_is_subprog_call(const struct bpf_insn *insn)
{
return BPF_CLASS(insn->code) == BPF_JMP &&
BPF_OP(insn->code) == BPF_CALL &&
BPF_SRC(insn->code) == BPF_K &&
insn->src_reg == BPF_PSEUDO_CALL &&
insn->dst_reg == 0 &&
insn->off == 0;
}
static bool is_call_insn(const struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_CALL);
}
static bool insn_is_pseudo_func(struct bpf_insn *insn)
{
return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
}
static int
bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
const char *name, size_t sec_idx, const char *sec_name,
size_t sec_off, void *insn_data, size_t insn_data_sz)
{
if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) {
pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n",
sec_name, name, sec_off, insn_data_sz);
return -EINVAL;
}
memset(prog, 0, sizeof(*prog));
prog->obj = obj;
prog->sec_idx = sec_idx;
prog->sec_insn_off = sec_off / BPF_INSN_SZ;
prog->sec_insn_cnt = insn_data_sz / BPF_INSN_SZ;
/* insns_cnt can later be increased by appending used subprograms */
prog->insns_cnt = prog->sec_insn_cnt;
prog->type = BPF_PROG_TYPE_UNSPEC;
prog->fd = -1;
/* libbpf's convention for SEC("?abc...") is that it's just like
* SEC("abc...") but the corresponding bpf_program starts out with
* autoload set to false.
*/
if (sec_name[0] == '?') {
prog->autoload = false;
/* from now on forget there was ? in section name */
sec_name++;
} else {
prog->autoload = true;
}
prog->autoattach = true;
/* inherit object's log_level */
prog->log_level = obj->log_level;
prog->sec_name = strdup(sec_name);
if (!prog->sec_name)
goto errout;
prog->name = strdup(name);
if (!prog->name)
goto errout;
prog->insns = malloc(insn_data_sz);
if (!prog->insns)
goto errout;
memcpy(prog->insns, insn_data, insn_data_sz);
return 0;
errout:
pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name);
bpf_program__exit(prog);
return -ENOMEM;
}
static int
bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
const char *sec_name, int sec_idx)
{
Elf_Data *symbols = obj->efile.symbols;
struct bpf_program *prog, *progs;
void *data = sec_data->d_buf;
size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms;
int nr_progs, err, i;
const char *name;
Elf64_Sym *sym;
progs = obj->programs;
nr_progs = obj->nr_programs;
nr_syms = symbols->d_size / sizeof(Elf64_Sym);
sec_off = 0;
for (i = 0; i < nr_syms; i++) {
sym = elf_sym_by_idx(obj, i);
if (sym->st_shndx != sec_idx)
continue;
if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
prog_sz = sym->st_size;
sec_off = sym->st_value;
name = elf_sym_str(obj, sym->st_name);
if (!name) {
pr_warn("sec '%s': failed to get symbol name for offset %zu\n",
sec_name, sec_off);
return -LIBBPF_ERRNO__FORMAT;
}
if (sec_off + prog_sz > sec_sz) {
pr_warn("sec '%s': program at offset %zu crosses section boundary\n",
sec_name, sec_off);
return -LIBBPF_ERRNO__FORMAT;
}
if (sec_idx != obj->efile.text_shndx && ELF64_ST_BIND(sym->st_info) == STB_LOCAL) {
pr_warn("sec '%s': program '%s' is static and not supported\n", sec_name, name);
return -ENOTSUP;
}
pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n",
sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz);
progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(*progs));
if (!progs) {
/*
* In this case the original obj->programs
* is still valid, so don't need special treat for
* bpf_close_object().
*/
pr_warn("sec '%s': failed to alloc memory for new program '%s'\n",
sec_name, name);
return -ENOMEM;
}
obj->programs = progs;
prog = &progs[nr_progs];
err = bpf_object__init_prog(obj, prog, name, sec_idx, sec_name,
sec_off, data + sec_off, prog_sz);
if (err)
return err;
/* if function is a global/weak symbol, but has restricted
* (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF FUNC
* as static to enable more permissive BPF verification mode
* with more outside context available to BPF verifier
*/
if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL
&& (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
|| ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL))
prog->mark_btf_static = true;
nr_progs++;
obj->nr_programs = nr_progs;
}
return 0;
}
static const struct btf_member *
find_member_by_offset(const struct btf_type *t, __u32 bit_offset)
{
struct btf_member *m;
int i;
for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
if (btf_member_bit_offset(t, i) == bit_offset)
return m;
}
return NULL;
}
static const struct btf_member *
find_member_by_name(const struct btf *btf, const struct btf_type *t,
const char *name)
{
struct btf_member *m;
int i;
for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
if (!strcmp(btf__name_by_offset(btf, m->name_off), name))
return m;
}
return NULL;
}
#define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
const char *name, __u32 kind);
static int
find_struct_ops_kern_types(const struct btf *btf, const char *tname,
const struct btf_type **type, __u32 *type_id,
const struct btf_type **vtype, __u32 *vtype_id,
const struct btf_member **data_member)
{
const struct btf_type *kern_type, *kern_vtype;
const struct btf_member *kern_data_member;
__s32 kern_vtype_id, kern_type_id;
__u32 i;
kern_type_id = btf__find_by_name_kind(btf, tname, BTF_KIND_STRUCT);
if (kern_type_id < 0) {
pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
tname);
return kern_type_id;
}
kern_type = btf__type_by_id(btf, kern_type_id);
/* Find the corresponding "map_value" type that will be used
* in map_update(BPF_MAP_TYPE_STRUCT_OPS). For example,
* find "struct bpf_struct_ops_tcp_congestion_ops" from the
* btf_vmlinux.
*/
kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX,
tname, BTF_KIND_STRUCT);
if (kern_vtype_id < 0) {
pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n",
STRUCT_OPS_VALUE_PREFIX, tname);
return kern_vtype_id;
}
kern_vtype = btf__type_by_id(btf, kern_vtype_id);
/* Find "struct tcp_congestion_ops" from
* struct bpf_struct_ops_tcp_congestion_ops {
* [ ... ]
* struct tcp_congestion_ops data;
* }
*/
kern_data_member = btf_members(kern_vtype);
for (i = 0; i < btf_vlen(kern_vtype); i++, kern_data_member++) {
if (kern_data_member->type == kern_type_id)
break;
}
if (i == btf_vlen(kern_vtype)) {
pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n",
tname, STRUCT_OPS_VALUE_PREFIX, tname);
return -EINVAL;
}
*type = kern_type;
*type_id = kern_type_id;
*vtype = kern_vtype;
*vtype_id = kern_vtype_id;
*data_member = kern_data_member;
return 0;
}
static bool bpf_map__is_struct_ops(const struct bpf_map *map)
{
return map->def.type == BPF_MAP_TYPE_STRUCT_OPS;
}
/* Init the map's fields that depend on kern_btf */
static int bpf_map__init_kern_struct_ops(struct bpf_map *map,
const struct btf *btf,
const struct btf *kern_btf)
{
const struct btf_member *member, *kern_member, *kern_data_member;
const struct btf_type *type, *kern_type, *kern_vtype;
__u32 i, kern_type_id, kern_vtype_id, kern_data_off;
struct bpf_struct_ops *st_ops;
void *data, *kern_data;
const char *tname;
int err;
st_ops = map->st_ops;
type = st_ops->type;
tname = st_ops->tname;
err = find_struct_ops_kern_types(kern_btf, tname,
&kern_type, &kern_type_id,
&kern_vtype, &kern_vtype_id,
&kern_data_member);
if (err)
return err;
pr_debug("struct_ops init_kern %s: type_id:%u kern_type_id:%u kern_vtype_id:%u\n",
map->name, st_ops->type_id, kern_type_id, kern_vtype_id);
map->def.value_size = kern_vtype->size;
map->btf_vmlinux_value_type_id = kern_vtype_id;
st_ops->kern_vdata = calloc(1, kern_vtype->size);
if (!st_ops->kern_vdata)
return -ENOMEM;
data = st_ops->data;
kern_data_off = kern_data_member->offset / 8;
kern_data = st_ops->kern_vdata + kern_data_off;
member = btf_members(type);
for (i = 0; i < btf_vlen(type); i++, member++) {
const struct btf_type *mtype, *kern_mtype;
__u32 mtype_id, kern_mtype_id;
void *mdata, *kern_mdata;
__s64 msize, kern_msize;
__u32 moff, kern_moff;
__u32 kern_member_idx;
const char *mname;
mname = btf__name_by_offset(btf, member->name_off);
kern_member = find_member_by_name(kern_btf, kern_type, mname);
if (!kern_member) {
pr_warn("struct_ops init_kern %s: Cannot find member %s in kernel BTF\n",
map->name, mname);
return -ENOTSUP;
}
kern_member_idx = kern_member - btf_members(kern_type);
if (btf_member_bitfield_size(type, i) ||
btf_member_bitfield_size(kern_type, kern_member_idx)) {
pr_warn("struct_ops init_kern %s: bitfield %s is not supported\n",
map->name, mname);
return -ENOTSUP;
}
moff = member->offset / 8;
kern_moff = kern_member->offset / 8;
mdata = data + moff;
kern_mdata = kern_data + kern_moff;
mtype = skip_mods_and_typedefs(btf, member->type, &mtype_id);
kern_mtype = skip_mods_and_typedefs(kern_btf, kern_member->type,
&kern_mtype_id);
if (BTF_INFO_KIND(mtype->info) !=
BTF_INFO_KIND(kern_mtype->info)) {
pr_warn("struct_ops init_kern %s: Unmatched member type %s %u != %u(kernel)\n",
map->name, mname, BTF_INFO_KIND(mtype->info),
BTF_INFO_KIND(kern_mtype->info));
return -ENOTSUP;
}
if (btf_is_ptr(mtype)) {
struct bpf_program *prog;
prog = st_ops->progs[i];
if (!prog)
continue;
kern_mtype = skip_mods_and_typedefs(kern_btf,
kern_mtype->type,
&kern_mtype_id);
/* mtype->type must be a func_proto which was
* guaranteed in bpf_object__collect_st_ops_relos(),
* so only check kern_mtype for func_proto here.
*/
if (!btf_is_func_proto(kern_mtype)) {
pr_warn("struct_ops init_kern %s: kernel member %s is not a func ptr\n",
map->name, mname);
return -ENOTSUP;
}
prog->attach_btf_id = kern_type_id;
prog->expected_attach_type = kern_member_idx;
st_ops->kern_func_off[i] = kern_data_off + kern_moff;
pr_debug("struct_ops init_kern %s: func ptr %s is set to prog %s from data(+%u) to kern_data(+%u)\n",
map->name, mname, prog->name, moff,
kern_moff);
continue;
}
msize = btf__resolve_size(btf, mtype_id);
kern_msize = btf__resolve_size(kern_btf, kern_mtype_id);
if (msize < 0 || kern_msize < 0 || msize != kern_msize) {
pr_warn("struct_ops init_kern %s: Error in size of member %s: %zd != %zd(kernel)\n",
map->name, mname, (ssize_t)msize,
(ssize_t)kern_msize);
return -ENOTSUP;
}
pr_debug("struct_ops init_kern %s: copy %s %u bytes from data(+%u) to kern_data(+%u)\n",
map->name, mname, (unsigned int)msize,
moff, kern_moff);
memcpy(kern_mdata, mdata, msize);
}
return 0;
}
static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
{
struct bpf_map *map;
size_t i;
int err;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
if (!bpf_map__is_struct_ops(map))
continue;
err = bpf_map__init_kern_struct_ops(map, obj->btf,
obj->btf_vmlinux);
if (err)
return err;
}
return 0;
}
static int bpf_object__init_struct_ops_maps(struct bpf_object *obj)
{
const struct btf_type *type, *datasec;
const struct btf_var_secinfo *vsi;
struct bpf_struct_ops *st_ops;
const char *tname, *var_name;
__s32 type_id, datasec_id;
const struct btf *btf;
struct bpf_map *map;
__u32 i;
if (obj->efile.st_ops_shndx == -1)
return 0;
btf = obj->btf;
datasec_id = btf__find_by_name_kind(btf, STRUCT_OPS_SEC,
BTF_KIND_DATASEC);
if (datasec_id < 0) {
pr_warn("struct_ops init: DATASEC %s not found\n",
STRUCT_OPS_SEC);
return -EINVAL;
}
datasec = btf__type_by_id(btf, datasec_id);
vsi = btf_var_secinfos(datasec);
for (i = 0; i < btf_vlen(datasec); i++, vsi++) {
type = btf__type_by_id(obj->btf, vsi->type);
var_name = btf__name_by_offset(obj->btf, type->name_off);
type_id = btf__resolve_type(obj->btf, vsi->type);
if (type_id < 0) {
pr_warn("struct_ops init: Cannot resolve var type_id %u in DATASEC %s\n",
vsi->type, STRUCT_OPS_SEC);
return -EINVAL;
}
type = btf__type_by_id(obj->btf, type_id);
tname = btf__name_by_offset(obj->btf, type->name_off);
if (!tname[0]) {
pr_warn("struct_ops init: anonymous type is not supported\n");
return -ENOTSUP;
}
if (!btf_is_struct(type)) {
pr_warn("struct_ops init: %s is not a struct\n", tname);
return -EINVAL;
}
map = bpf_object__add_map(obj);
if (IS_ERR(map))
return PTR_ERR(map);
map->sec_idx = obj->efile.st_ops_shndx;
map->sec_offset = vsi->offset;
map->name = strdup(var_name);
if (!map->name)
return -ENOMEM;
map->def.type = BPF_MAP_TYPE_STRUCT_OPS;
map->def.key_size = sizeof(int);
map->def.value_size = type->size;
map->def.max_entries = 1;
map->st_ops = calloc(1, sizeof(*map->st_ops));
if (!map->st_ops)
return -ENOMEM;
st_ops = map->st_ops;
st_ops->data = malloc(type->size);
st_ops->progs = calloc(btf_vlen(type), sizeof(*st_ops->progs));
st_ops->kern_func_off = malloc(btf_vlen(type) *
sizeof(*st_ops->kern_func_off));
if (!st_ops->data || !st_ops->progs || !st_ops->kern_func_off)
return -ENOMEM;
if (vsi->offset + type->size > obj->efile.st_ops_data->d_size) {
pr_warn("struct_ops init: var %s is beyond the end of DATASEC %s\n",
var_name, STRUCT_OPS_SEC);
return -EINVAL;
}
memcpy(st_ops->data,
obj->efile.st_ops_data->d_buf + vsi->offset,
type->size);
st_ops->tname = tname;
st_ops->type = type;
st_ops->type_id = type_id;
pr_debug("struct_ops init: struct %s(type_id=%u) %s found at offset %u\n",
tname, type_id, var_name, vsi->offset);
}
return 0;
}
static struct bpf_object *bpf_object__new(const char *path,
const void *obj_buf,
size_t obj_buf_sz,
const char *obj_name)
{
struct bpf_object *obj;
char *end;
obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
if (!obj) {
pr_warn("alloc memory failed for %s\n", path);
return ERR_PTR(-ENOMEM);
}
strcpy(obj->path, path);
if (obj_name) {
libbpf_strlcpy(obj->name, obj_name, sizeof(obj->name));
} else {
/* Using basename() GNU version which doesn't modify arg. */
libbpf_strlcpy(obj->name, basename((void *)path), sizeof(obj->name));
end = strchr(obj->name, '.');
if (end)
*end = 0;
}
obj->efile.fd = -1;
/*
* Caller of this function should also call
* bpf_object__elf_finish() after data collection to return
* obj_buf to user. If not, we should duplicate the buffer to
* avoid user freeing them before elf finish.
*/
obj->efile.obj_buf = obj_buf;
obj->efile.obj_buf_sz = obj_buf_sz;
obj->efile.btf_maps_shndx = -1;
obj->efile.st_ops_shndx = -1;
obj->kconfig_map_idx = -1;
obj->kern_version = get_kernel_version();
obj->loaded = false;
return obj;
}
static void bpf_object__elf_finish(struct bpf_object *obj)
{
if (!obj->efile.elf)
return;
elf_end(obj->efile.elf);
obj->efile.elf = NULL;
obj->efile.symbols = NULL;
obj->efile.st_ops_data = NULL;
zfree(&obj->efile.secs);
obj->efile.sec_cnt = 0;
zclose(obj->efile.fd);
obj->efile.obj_buf = NULL;
obj->efile.obj_buf_sz = 0;
}
static int bpf_object__elf_init(struct bpf_object *obj)
{
Elf64_Ehdr *ehdr;
int err = 0;
Elf *elf;
if (obj->efile.elf) {
pr_warn("elf: init internal error\n");
return -LIBBPF_ERRNO__LIBELF;
}
if (obj->efile.obj_buf_sz > 0) {
/* obj_buf should have been validated by bpf_object__open_mem(). */
elf = elf_memory((char *)obj->efile.obj_buf, obj->efile.obj_buf_sz);
} else {
obj->efile.fd = open(obj->path, O_RDONLY | O_CLOEXEC);
if (obj->efile.fd < 0) {
char errmsg[STRERR_BUFSIZE], *cp;
err = -errno;
cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
pr_warn("elf: failed to open %s: %s\n", obj->path, cp);
return err;
}
elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
}
if (!elf) {
pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1));
err = -LIBBPF_ERRNO__LIBELF;
goto errout;
}
obj->efile.elf = elf;
if (elf_kind(elf) != ELF_K_ELF) {
err = -LIBBPF_ERRNO__FORMAT;
pr_warn("elf: '%s' is not a proper ELF object\n", obj->path);
goto errout;
}
if (gelf_getclass(elf) != ELFCLASS64) {
err = -LIBBPF_ERRNO__FORMAT;
pr_warn("elf: '%s' is not a 64-bit ELF object\n", obj->path);
goto errout;
}
obj->efile.ehdr = ehdr = elf64_getehdr(elf);
if (!obj->efile.ehdr) {
pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1));
err = -LIBBPF_ERRNO__FORMAT;
goto errout;
}
if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) {
pr_warn("elf: failed to get section names section index for %s: %s\n",
obj->path, elf_errmsg(-1));
err = -LIBBPF_ERRNO__FORMAT;
goto errout;
}
/* Elf is corrupted/truncated, avoid calling elf_strptr. */
if (!elf_rawdata(elf_getscn(elf, obj->efile.shstrndx), NULL)) {
pr_warn("elf: failed to get section names strings from %s: %s\n",
obj->path, elf_errmsg(-1));
err = -LIBBPF_ERRNO__FORMAT;
goto errout;
}
/* Old LLVM set e_machine to EM_NONE */
if (ehdr->e_type != ET_REL || (ehdr->e_machine && ehdr->e_machine != EM_BPF)) {
pr_warn("elf: %s is not a valid eBPF object file\n", obj->path);
err = -LIBBPF_ERRNO__FORMAT;
goto errout;
}
return 0;
errout:
bpf_object__elf_finish(obj);
return err;
}
static int bpf_object__check_endianness(struct bpf_object *obj)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
return 0;
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
return 0;
#else
# error "Unrecognized __BYTE_ORDER__"
#endif
pr_warn("elf: endianness mismatch in %s.\n", obj->path);
return -LIBBPF_ERRNO__ENDIAN;
}
static int
bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
{
if (!data) {
pr_warn("invalid license section in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
/* libbpf_strlcpy() only copies first N - 1 bytes, so size + 1 won't
* go over allowed ELF data section buffer
*/
libbpf_strlcpy(obj->license, data, min(size + 1, sizeof(obj->license)));
pr_debug("license of %s is %s\n", obj->path, obj->license);
return 0;
}
static int
bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
{
__u32 kver;
if (!data || size != sizeof(kver)) {
pr_warn("invalid kver section in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
memcpy(&kver, data, sizeof(kver));
obj->kern_version = kver;
pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
return 0;
}
static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
{
if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
type == BPF_MAP_TYPE_HASH_OF_MAPS)
return true;
return false;
}
static int find_elf_sec_sz(const struct bpf_object *obj, const char *name, __u32 *size)
{
Elf_Data *data;
Elf_Scn *scn;
if (!name)
return -EINVAL;
scn = elf_sec_by_name(obj, name);
data = elf_sec_data(obj, scn);
if (data) {
*size = data->d_size;
return 0; /* found it */
}
return -ENOENT;
}
static Elf64_Sym *find_elf_var_sym(const struct bpf_object *obj, const char *name)
{
Elf_Data *symbols = obj->efile.symbols;
const char *sname;
size_t si;
for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) {
Elf64_Sym *sym = elf_sym_by_idx(obj, si);
if (ELF64_ST_TYPE(sym->st_info) != STT_OBJECT)
continue;
if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
ELF64_ST_BIND(sym->st_info) != STB_WEAK)
continue;
sname = elf_sym_str(obj, sym->st_name);
if (!sname) {
pr_warn("failed to get sym name string for var %s\n", name);
return ERR_PTR(-EIO);
}
if (strcmp(name, sname) == 0)
return sym;
}
return ERR_PTR(-ENOENT);
}
static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
{
struct bpf_map *map;
int err;
err = libbpf_ensure_mem((void **)&obj->maps, &obj->maps_cap,
sizeof(*obj->maps), obj->nr_maps + 1);
if (err)
return ERR_PTR(err);
map = &obj->maps[obj->nr_maps++];
map->obj = obj;
map->fd = -1;
map->inner_map_fd = -1;
map->autocreate = true;
return map;
}
static size_t bpf_map_mmap_sz(const struct bpf_map *map)
{
long page_sz = sysconf(_SC_PAGE_SIZE);
size_t map_sz;
map_sz = (size_t)roundup(map->def.value_size, 8) * map->def.max_entries;
map_sz = roundup(map_sz, page_sz);
return map_sz;
}
static char *internal_map_name(struct bpf_object *obj, const char *real_name)
{
char map_name[BPF_OBJ_NAME_LEN], *p;
int pfx_len, sfx_len = max((size_t)7, strlen(real_name));
/* This is one of the more confusing parts of libbpf for various
* reasons, some of which are historical. The original idea for naming
* internal names was to include as much of BPF object name prefix as
* possible, so that it can be distinguished from similar internal
* maps of a different BPF object.
* As an example, let's say we have bpf_object named 'my_object_name'
* and internal map corresponding to '.rodata' ELF section. The final
* map name advertised to user and to the kernel will be
* 'my_objec.rodata', taking first 8 characters of object name and
* entire 7 characters of '.rodata'.
* Somewhat confusingly, if internal map ELF section name is shorter
* than 7 characters, e.g., '.bss', we still reserve 7 characters
* for the suffix, even though we only have 4 actual characters, and
* resulting map will be called 'my_objec.bss', not even using all 15
* characters allowed by the kernel. Oh well, at least the truncated
* object name is somewhat consistent in this case. But if the map
* name is '.kconfig', we'll still have entirety of '.kconfig' added
* (8 chars) and thus will be left with only first 7 characters of the
* object name ('my_obje'). Happy guessing, user, that the final map
* name will be "my_obje.kconfig".
* Now, with libbpf starting to support arbitrarily named .rodata.*
* and .data.* data sections, it's possible that ELF section name is
* longer than allowed 15 chars, so we now need to be careful to take
* only up to 15 first characters of ELF name, taking no BPF object
* name characters at all. So '.rodata.abracadabra' will result in
* '.rodata.abracad' kernel and user-visible name.
* We need to keep this convoluted logic intact for .data, .bss and
* .rodata maps, but for new custom .data.custom and .rodata.custom
* maps we use their ELF names as is, not prepending bpf_object name
* in front. We still need to truncate them to 15 characters for the
* kernel. Full name can be recovered for such maps by using DATASEC
* BTF type associated with such map's value type, though.
*/
if (sfx_len >= BPF_OBJ_NAME_LEN)
sfx_len = BPF_OBJ_NAME_LEN - 1;
/* if there are two or more dots in map name, it's a custom dot map */
if (strchr(real_name + 1, '.') != NULL)
pfx_len = 0;
else
pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1, strlen(obj->name));
snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name,
sfx_len, real_name);
/* sanitise map name to characters allowed by kernel */
for (p = map_name; *p && p < map_name + sizeof(map_name); p++)
if (!isalnum(*p) && *p != '_' && *p != '.')
*p = '_';
return strdup(map_name);
}
static int
map_fill_btf_type_info(struct bpf_object *obj, struct bpf_map *map);
/* Internal BPF map is mmap()'able only if at least one of corresponding
* DATASEC's VARs are to be exposed through BPF skeleton. I.e., it's a GLOBAL
* variable and it's not marked as __hidden (which turns it into, effectively,
* a STATIC variable).
*/
static bool map_is_mmapable(struct bpf_object *obj, struct bpf_map *map)
{
const struct btf_type *t, *vt;
struct btf_var_secinfo *vsi;
int i, n;
if (!map->btf_value_type_id)
return false;
t = btf__type_by_id(obj->btf, map->btf_value_type_id);
if (!btf_is_datasec(t))
return false;
vsi = btf_var_secinfos(t);
for (i = 0, n = btf_vlen(t); i < n; i++, vsi++) {
vt = btf__type_by_id(obj->btf, vsi->type);
if (!btf_is_var(vt))
continue;
if (btf_var(vt)->linkage != BTF_VAR_STATIC)
return true;
}
return false;
}
static int
bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
const char *real_name, int sec_idx, void *data, size_t data_sz)
{
struct bpf_map_def *def;
struct bpf_map *map;
int err;
map = bpf_object__add_map(obj);
if (IS_ERR(map))
return PTR_ERR(map);
map->libbpf_type = type;
map->sec_idx = sec_idx;
map->sec_offset = 0;
map->real_name = strdup(real_name);
map->name = internal_map_name(obj, real_name);
if (!map->real_name || !map->name) {
zfree(&map->real_name);
zfree(&map->name);
return -ENOMEM;
}
def = &map->def;
def->type = BPF_MAP_TYPE_ARRAY;
def->key_size = sizeof(int);
def->value_size = data_sz;
def->max_entries = 1;
def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_KCONFIG
? BPF_F_RDONLY_PROG : 0;
/* failures are fine because of maps like .rodata.str1.1 */
(void) map_fill_btf_type_info(obj, map);
if (map_is_mmapable(obj, map))
def->map_flags |= BPF_F_MMAPABLE;
pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
map->name, map->sec_idx, map->sec_offset, def->map_flags);
map->mmaped = mmap(NULL, bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (map->mmaped == MAP_FAILED) {
err = -errno;
map->mmaped = NULL;
pr_warn("failed to alloc map '%s' content buffer: %d\n",
map->name, err);
zfree(&map->real_name);
zfree(&map->name);
return err;
}
if (data)
memcpy(map->mmaped, data, data_sz);
pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
return 0;
}
static int bpf_object__init_global_data_maps(struct bpf_object *obj)
{
struct elf_sec_desc *sec_desc;
const char *sec_name;
int err = 0, sec_idx;
/*
* Populate obj->maps with libbpf internal maps.
*/
for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
sec_desc = &obj->efile.secs[sec_idx];
/* Skip recognized sections with size 0. */
if (!sec_desc->data || sec_desc->data->d_size == 0)
continue;
switch (sec_desc->sec_type) {
case SEC_DATA:
sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
sec_name, sec_idx,
sec_desc->data->d_buf,
sec_desc->data->d_size);
break;
case SEC_RODATA:
obj->has_rodata = true;
sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
sec_name, sec_idx,
sec_desc->data->d_buf,
sec_desc->data->d_size);
break;
case SEC_BSS:
sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
sec_name, sec_idx,
NULL,
sec_desc->data->d_size);
break;
default:
/* skip */
break;
}
if (err)
return err;
}
return 0;
}
static struct extern_desc *find_extern_by_name(const struct bpf_object *obj,
const void *name)
{
int i;
for (i = 0; i < obj->nr_extern; i++) {
if (strcmp(obj->externs[i].name, name) == 0)
return &obj->externs[i];
}
return NULL;
}
static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
char value)
{
switch (ext->kcfg.type) {
case KCFG_BOOL:
if (value == 'm') {
pr_warn("extern (kcfg) '%s': value '%c' implies tristate or char type\n",
ext->name, value);
return -EINVAL;
}
*(bool *)ext_val = value == 'y' ? true : false;
break;
case KCFG_TRISTATE:
if (value == 'y')
*(enum libbpf_tristate *)ext_val = TRI_YES;
else if (value == 'm')
*(enum libbpf_tristate *)ext_val = TRI_MODULE;
else /* value == 'n' */
*(enum libbpf_tristate *)ext_val = TRI_NO;
break;
case KCFG_CHAR:
*(char *)ext_val = value;
break;
case KCFG_UNKNOWN:
case KCFG_INT:
case KCFG_CHAR_ARR:
default:
pr_warn("extern (kcfg) '%s': value '%c' implies bool, tristate, or char type\n",
ext->name, value);
return -EINVAL;
}
ext->is_set = true;
return 0;
}
static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val,
const char *value)
{
size_t len;
if (ext->kcfg.type != KCFG_CHAR_ARR) {
pr_warn("extern (kcfg) '%s': value '%s' implies char array type\n",
ext->name, value);
return -EINVAL;
}
len = strlen(value);
if (value[len - 1] != '"') {
pr_warn("extern (kcfg) '%s': invalid string config '%s'\n",
ext->name, value);
return -EINVAL;
}
/* strip quotes */
len -= 2;
if (len >= ext->kcfg.sz) {
pr_warn("extern (kcfg) '%s': long string '%s' of (%zu bytes) truncated to %d bytes\n",
ext->name, value, len, ext->kcfg.sz - 1);
len = ext->kcfg.sz - 1;
}
memcpy(ext_val, value + 1, len);
ext_val[len] = '\0';
ext->is_set = true;
return 0;
}
static int parse_u64(const char *value, __u64 *res)
{
char *value_end;
int err;
errno = 0;
*res = strtoull(value, &value_end, 0);
if (errno) {
err = -errno;
pr_warn("failed to parse '%s' as integer: %d\n", value, err);
return err;
}
if (*value_end) {
pr_warn("failed to parse '%s' as integer completely\n", value);
return -EINVAL;
}
return 0;
}
static bool is_kcfg_value_in_range(const struct extern_desc *ext, __u64 v)
{
int bit_sz = ext->kcfg.sz * 8;
if (ext->kcfg.sz == 8)
return true;
/* Validate that value stored in u64 fits in integer of `ext->sz`
* bytes size without any loss of information. If the target integer
* is signed, we rely on the following limits of integer type of
* Y bits and subsequent transformation:
*
* -2^(Y-1) <= X <= 2^(Y-1) - 1
* 0 <= X + 2^(Y-1) <= 2^Y - 1
* 0 <= X + 2^(Y-1) < 2^Y
*
* For unsigned target integer, check that all the (64 - Y) bits are
* zero.
*/
if (ext->kcfg.is_signed)
return v + (1ULL << (bit_sz - 1)) < (1ULL << bit_sz);
else
return (v >> bit_sz) == 0;
}
static int set_kcfg_value_num(struct extern_desc *ext, void *ext_val,
__u64 value)
{
if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR &&
ext->kcfg.type != KCFG_BOOL) {
pr_warn("extern (kcfg) '%s': value '%llu' implies integer, char, or boolean type\n",
ext->name, (unsigned long long)value);
return -EINVAL;
}
if (ext->kcfg.type == KCFG_BOOL && value > 1) {
pr_warn("extern (kcfg) '%s': value '%llu' isn't boolean compatible\n",
ext->name, (unsigned long long)value);
return -EINVAL;
}
if (!is_kcfg_value_in_range(ext, value)) {
pr_warn("extern (kcfg) '%s': value '%llu' doesn't fit in %d bytes\n",
ext->name, (unsigned long long)value, ext->kcfg.sz);
return -ERANGE;
}
switch (ext->kcfg.sz) {
case 1:
*(__u8 *)ext_val = value;
break;
case 2:
*(__u16 *)ext_val = value;
break;
case 4:
*(__u32 *)ext_val = value;
break;
case 8:
*(__u64 *)ext_val = value;
break;
default:
return -EINVAL;
}
ext->is_set = true;
return 0;
}
static int bpf_object__process_kconfig_line(struct bpf_object *obj,
char *buf, void *data)
{
struct extern_desc *ext;
char *sep, *value;
int len, err = 0;
void *ext_val;
__u64 num;
if (!str_has_pfx(buf, "CONFIG_"))
return 0;
sep = strchr(buf, '=');
if (!sep) {
pr_warn("failed to parse '%s': no separator\n", buf);
return -EINVAL;
}
/* Trim ending '\n' */
len = strlen(buf);
if (buf[len - 1] == '\n')
buf[len - 1] = '\0';
/* Split on '=' and ensure that a value is present. */
*sep = '\0';
if (!sep[1]) {
*sep = '=';
pr_warn("failed to parse '%s': no value\n", buf);
return -EINVAL;
}
ext = find_extern_by_name(obj, buf);
if (!ext || ext->is_set)
return 0;
ext_val = data + ext->kcfg.data_off;
value = sep + 1;
switch (*value) {
case 'y': case 'n': case 'm':
err = set_kcfg_value_tri(ext, ext_val, *value);
break;
case '"':
err = set_kcfg_value_str(ext, ext_val, value);
break;
default:
/* assume integer */
err = parse_u64(value, &num);
if (err) {
pr_warn("extern (kcfg) '%s': value '%s' isn't a valid integer\n", ext->name, value);
return err;
}
if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR) {
pr_warn("extern (kcfg) '%s': value '%s' implies integer type\n", ext->name, value);
return -EINVAL;
}
err = set_kcfg_value_num(ext, ext_val, num);
break;
}
if (err)
return err;
pr_debug("extern (kcfg) '%s': set to %s\n", ext->name, value);
return 0;
}
static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data)
{
char buf[PATH_MAX];
struct utsname uts;
int len, err = 0;
gzFile file;
uname(&uts);
len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release);
if (len < 0)
return -EINVAL;
else if (len >= PATH_MAX)
return -ENAMETOOLONG;
/* gzopen also accepts uncompressed files. */
file = gzopen(buf, "r");
if (!file)
file = gzopen("/proc/config.gz", "r");
if (!file) {
pr_warn("failed to open system Kconfig\n");
return -ENOENT;
}
while (gzgets(file, buf, sizeof(buf))) {
err = bpf_object__process_kconfig_line(obj, buf, data);
if (err) {
pr_warn("error parsing system Kconfig line '%s': %d\n",
buf, err);
goto out;
}
}
out:
gzclose(file);
return err;
}
static int bpf_object__read_kconfig_mem(struct bpf_object *obj,
const char *config, void *data)
{
char buf[PATH_MAX];
int err = 0;
FILE *file;
file = fmemopen((void *)config, strlen(config), "r");
if (!file) {
err = -errno;
pr_warn("failed to open in-memory Kconfig: %d\n", err);
return err;
}
while (fgets(buf, sizeof(buf), file)) {
err = bpf_object__process_kconfig_line(obj, buf, data);
if (err) {
pr_warn("error parsing in-memory Kconfig line '%s': %d\n",
buf, err);
break;
}
}
fclose(file);
return err;
}
static int bpf_object__init_kconfig_map(struct bpf_object *obj)
{
struct extern_desc *last_ext = NULL, *ext;
size_t map_sz;
int i, err;
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type == EXT_KCFG)
last_ext = ext;
}
if (!last_ext)
return 0;
map_sz = last_ext->kcfg.data_off + last_ext->kcfg.sz;
err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG,
".kconfig", obj->efile.symbols_shndx,
NULL, map_sz);
if (err)
return err;
obj->kconfig_map_idx = obj->nr_maps - 1;
return 0;
}
const struct btf_type *
skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
{
const struct btf_type *t = btf__type_by_id(btf, id);
if (res_id)
*res_id = id;
while (btf_is_mod(t) || btf_is_typedef(t)) {
if (res_id)
*res_id = t->type;
t = btf__type_by_id(btf, t->type);
}
return t;
}
static const struct btf_type *
resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
{
const struct btf_type *t;
t = skip_mods_and_typedefs(btf, id, NULL);
if (!btf_is_ptr(t))
return NULL;
t = skip_mods_and_typedefs(btf, t->type, res_id);
return btf_is_func_proto(t) ? t : NULL;
}
static const char *__btf_kind_str(__u16 kind)
{
switch (kind) {
case BTF_KIND_UNKN: return "void";
case BTF_KIND_INT: return "int";
case BTF_KIND_PTR: return "ptr";
case BTF_KIND_ARRAY: return "array";
case BTF_KIND_STRUCT: return "struct";
case BTF_KIND_UNION: return "union";
case BTF_KIND_ENUM: return "enum";
case BTF_KIND_FWD: return "fwd";
case BTF_KIND_TYPEDEF: return "typedef";
case BTF_KIND_VOLATILE: return "volatile";
case BTF_KIND_CONST: return "const";
case BTF_KIND_RESTRICT: return "restrict";
case BTF_KIND_FUNC: return "func";
case BTF_KIND_FUNC_PROTO: return "func_proto";
case BTF_KIND_VAR: return "var";
case BTF_KIND_DATASEC: return "datasec";
case BTF_KIND_FLOAT: return "float";
case BTF_KIND_DECL_TAG: return "decl_tag";
case BTF_KIND_TYPE_TAG: return "type_tag";
case BTF_KIND_ENUM64: return "enum64";
default: return "unknown";
}
}
const char *btf_kind_str(const struct btf_type *t)
{
return __btf_kind_str(btf_kind(t));
}
/*
* Fetch integer attribute of BTF map definition. Such attributes are
* represented using a pointer to an array, in which dimensionality of array
* encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
* encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
* type definition, while using only sizeof(void *) space in ELF data section.
*/
static bool get_map_field_int(const char *map_name, const struct btf *btf,
const struct btf_member *m, __u32 *res)
{
const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
const char *name = btf__name_by_offset(btf, m->name_off);
const struct btf_array *arr_info;
const struct btf_type *arr_t;
if (!btf_is_ptr(t)) {
pr_warn("map '%s': attr '%s': expected PTR, got %s.\n",
map_name, name, btf_kind_str(t));
return false;
}
arr_t = btf__type_by_id(btf, t->type);
if (!arr_t) {
pr_warn("map '%s': attr '%s': type [%u] not found.\n",
map_name, name, t->type);
return false;
}
if (!btf_is_array(arr_t)) {
pr_warn("map '%s': attr '%s': expected ARRAY, got %s.\n",
map_name, name, btf_kind_str(arr_t));
return false;
}
arr_info = btf_array(arr_t);
*res = arr_info->nelems;
return true;
}
static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)
{
int len;
len = snprintf(buf, buf_sz, "%s/%s", path, name);
if (len < 0)
return -EINVAL;
if (len >= buf_sz)
return -ENAMETOOLONG;
return 0;
}
static int build_map_pin_path(struct bpf_map *map, const char *path)
{
char buf[PATH_MAX];
int err;
if (!path)
path = "/sys/fs/bpf";
err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
if (err)
return err;
return bpf_map__set_pin_path(map, buf);
}
/* should match definition in bpf_helpers.h */
enum libbpf_pin_type {
LIBBPF_PIN_NONE,
/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
LIBBPF_PIN_BY_NAME,
};
int parse_btf_map_def(const char *map_name, struct btf *btf,
const struct btf_type *def_t, bool strict,
struct btf_map_def *map_def, struct btf_map_def *inner_def)
{
const struct btf_type *t;
const struct btf_member *m;
bool is_inner = inner_def == NULL;
int vlen, i;
vlen = btf_vlen(def_t);
m = btf_members(def_t);
for (i = 0; i < vlen; i++, m++) {
const char *name = btf__name_by_offset(btf, m->name_off);
if (!name) {
pr_warn("map '%s': invalid field #%d.\n", map_name, i);
return -EINVAL;
}
if (strcmp(name, "type") == 0) {
if (!get_map_field_int(map_name, btf, m, &map_def->map_type))
return -EINVAL;
map_def->parts |= MAP_DEF_MAP_TYPE;
} else if (strcmp(name, "max_entries") == 0) {
if (!get_map_field_int(map_name, btf, m, &map_def->max_entries))
return -EINVAL;
map_def->parts |= MAP_DEF_MAX_ENTRIES;
} else if (strcmp(name, "map_flags") == 0) {
if (!get_map_field_int(map_name, btf, m, &map_def->map_flags))
return -EINVAL;
map_def->parts |= MAP_DEF_MAP_FLAGS;
} else if (strcmp(name, "numa_node") == 0) {
if (!get_map_field_int(map_name, btf, m, &map_def->numa_node))
return -EINVAL;
map_def->parts |= MAP_DEF_NUMA_NODE;
} else if (strcmp(name, "key_size") == 0) {
__u32 sz;
if (!get_map_field_int(map_name, btf, m, &sz))
return -EINVAL;
if (map_def->key_size && map_def->key_size != sz) {
pr_warn("map '%s': conflicting key size %u != %u.\n",
map_name, map_def->key_size, sz);
return -EINVAL;
}
map_def->key_size = sz;
map_def->parts |= MAP_DEF_KEY_SIZE;
} else if (strcmp(name, "key") == 0) {
__s64 sz;
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': key type [%d] not found.\n",
map_name, m->type);
return -EINVAL;
}
if (!btf_is_ptr(t)) {
pr_warn("map '%s': key spec is not PTR: %s.\n",
map_name, btf_kind_str(t));
return -EINVAL;
}
sz = btf__resolve_size(btf, t->type);
if (sz < 0) {
pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n",
map_name, t->type, (ssize_t)sz);
return sz;
}
if (map_def->key_size && map_def->key_size != sz) {
pr_warn("map '%s': conflicting key size %u != %zd.\n",
map_name, map_def->key_size, (ssize_t)sz);
return -EINVAL;
}
map_def->key_size = sz;
map_def->key_type_id = t->type;
map_def->parts |= MAP_DEF_KEY_SIZE | MAP_DEF_KEY_TYPE;
} else if (strcmp(name, "value_size") == 0) {
__u32 sz;
if (!get_map_field_int(map_name, btf, m, &sz))
return -EINVAL;
if (map_def->value_size && map_def->value_size != sz) {
pr_warn("map '%s': conflicting value size %u != %u.\n",
map_name, map_def->value_size, sz);
return -EINVAL;
}
map_def->value_size = sz;
map_def->parts |= MAP_DEF_VALUE_SIZE;
} else if (strcmp(name, "value") == 0) {
__s64 sz;
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': value type [%d] not found.\n",
map_name, m->type);
return -EINVAL;
}
if (!btf_is_ptr(t)) {
pr_warn("map '%s': value spec is not PTR: %s.\n",
map_name, btf_kind_str(t));
return -EINVAL;
}
sz = btf__resolve_size(btf, t->type);
if (sz < 0) {
pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n",
map_name, t->type, (ssize_t)sz);
return sz;
}
if (map_def->value_size && map_def->value_size != sz) {
pr_warn("map '%s': conflicting value size %u != %zd.\n",
map_name, map_def->value_size, (ssize_t)sz);
return -EINVAL;
}
map_def->value_size = sz;
map_def->value_type_id = t->type;
map_def->parts |= MAP_DEF_VALUE_SIZE | MAP_DEF_VALUE_TYPE;
}
else if (strcmp(name, "values") == 0) {
bool is_map_in_map = bpf_map_type__is_map_in_map(map_def->map_type);
bool is_prog_array = map_def->map_type == BPF_MAP_TYPE_PROG_ARRAY;
const char *desc = is_map_in_map ? "map-in-map inner" : "prog-array value";
char inner_map_name[128];
int err;
if (is_inner) {
pr_warn("map '%s': multi-level inner maps not supported.\n",
map_name);
return -ENOTSUP;
}
if (i != vlen - 1) {
pr_warn("map '%s': '%s' member should be last.\n",
map_name, name);
return -EINVAL;
}
if (!is_map_in_map && !is_prog_array) {
pr_warn("map '%s': should be map-in-map or prog-array.\n",
map_name);
return -ENOTSUP;
}
if (map_def->value_size && map_def->value_size != 4) {
pr_warn("map '%s': conflicting value size %u != 4.\n",
map_name, map_def->value_size);
return -EINVAL;
}
map_def->value_size = 4;
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': %s type [%d] not found.\n",
map_name, desc, m->type);
return -EINVAL;
}
if (!btf_is_array(t) || btf_array(t)->nelems) {
pr_warn("map '%s': %s spec is not a zero-sized array.\n",
map_name, desc);
return -EINVAL;
}
t = skip_mods_and_typedefs(btf, btf_array(t)->type, NULL);
if (!btf_is_ptr(t)) {
pr_warn("map '%s': %s def is of unexpected kind %s.\n",
map_name, desc, btf_kind_str(t));
return -EINVAL;
}
t = skip_mods_and_typedefs(btf, t->type, NULL);
if (is_prog_array) {
if (!btf_is_func_proto(t)) {
pr_warn("map '%s': prog-array value def is of unexpected kind %s.\n",
map_name, btf_kind_str(t));
return -EINVAL;
}
continue;
}
if (!btf_is_struct(t)) {
pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
map_name, btf_kind_str(t));
return -EINVAL;
}
snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", map_name);
err = parse_btf_map_def(inner_map_name, btf, t, strict, inner_def, NULL);
if (err)
return err;
map_def->parts |= MAP_DEF_INNER_MAP;
} else if (strcmp(name, "pinning") == 0) {
__u32 val;
if (is_inner) {
pr_warn("map '%s': inner def can't be pinned.\n", map_name);
return -EINVAL;
}
if (!get_map_field_int(map_name, btf, m, &val))
return -EINVAL;
if (val != LIBBPF_PIN_NONE && val != LIBBPF_PIN_BY_NAME) {
pr_warn("map '%s': invalid pinning value %u.\n",
map_name, val);
return -EINVAL;
}
map_def->pinning = val;
map_def->parts |= MAP_DEF_PINNING;
} else if (strcmp(name, "map_extra") == 0) {
__u32 map_extra;
if (!get_map_field_int(map_name, btf, m, &map_extra))
return -EINVAL;
map_def->map_extra = map_extra;
map_def->parts |= MAP_DEF_MAP_EXTRA;
} else {
if (strict) {
pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
return -ENOTSUP;
}
pr_debug("map '%s': ignoring unknown field '%s'.\n", map_name, name);
}
}
if (map_def->map_type == BPF_MAP_TYPE_UNSPEC) {
pr_warn("map '%s': map type isn't specified.\n", map_name);
return -EINVAL;
}
return 0;
}
static size_t adjust_ringbuf_sz(size_t sz)
{
__u32 page_sz = sysconf(_SC_PAGE_SIZE);
__u32 mul;
/* if user forgot to set any size, make sure they see error */
if (sz == 0)
return 0;
/* Kernel expects BPF_MAP_TYPE_RINGBUF's max_entries to be
* a power-of-2 multiple of kernel's page size. If user diligently
* satisified these conditions, pass the size through.
*/
if ((sz % page_sz) == 0 && is_pow_of_2(sz / page_sz))
return sz;
/* Otherwise find closest (page_sz * power_of_2) product bigger than
* user-set size to satisfy both user size request and kernel
* requirements and substitute correct max_entries for map creation.
*/
for (mul = 1; mul <= UINT_MAX / page_sz; mul <<= 1) {
if (mul * page_sz > sz)
return mul * page_sz;
}
/* if it's impossible to satisfy the conditions (i.e., user size is
* very close to UINT_MAX but is not a power-of-2 multiple of
* page_size) then just return original size and let kernel reject it
*/
return sz;
}
static bool map_is_ringbuf(const struct bpf_map *map)
{
return map->def.type == BPF_MAP_TYPE_RINGBUF ||
map->def.type == BPF_MAP_TYPE_USER_RINGBUF;
}
static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def)
{
map->def.type = def->map_type;
map->def.key_size = def->key_size;
map->def.value_size = def->value_size;
map->def.max_entries = def->max_entries;
map->def.map_flags = def->map_flags;
map->map_extra = def->map_extra;
map->numa_node = def->numa_node;
map->btf_key_type_id = def->key_type_id;
map->btf_value_type_id = def->value_type_id;
/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
if (map_is_ringbuf(map))
map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
if (def->parts & MAP_DEF_MAP_TYPE)
pr_debug("map '%s': found type = %u.\n", map->name, def->map_type);
if (def->parts & MAP_DEF_KEY_TYPE)
pr_debug("map '%s': found key [%u], sz = %u.\n",
map->name, def->key_type_id, def->key_size);
else if (def->parts & MAP_DEF_KEY_SIZE)
pr_debug("map '%s': found key_size = %u.\n", map->name, def->key_size);
if (def->parts & MAP_DEF_VALUE_TYPE)
pr_debug("map '%s': found value [%u], sz = %u.\n",
map->name, def->value_type_id, def->value_size);
else if (def->parts & MAP_DEF_VALUE_SIZE)
pr_debug("map '%s': found value_size = %u.\n", map->name, def->value_size);
if (def->parts & MAP_DEF_MAX_ENTRIES)
pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries);
if (def->parts & MAP_DEF_MAP_FLAGS)
pr_debug("map '%s': found map_flags = 0x%x.\n", map->name, def->map_flags);
if (def->parts & MAP_DEF_MAP_EXTRA)
pr_debug("map '%s': found map_extra = 0x%llx.\n", map->name,
(unsigned long long)def->map_extra);
if (def->parts & MAP_DEF_PINNING)
pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
if (def->parts & MAP_DEF_NUMA_NODE)
pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node);
if (def->parts & MAP_DEF_INNER_MAP)
pr_debug("map '%s': found inner map definition.\n", map->name);
}
static const char *btf_var_linkage_str(__u32 linkage)
{
switch (linkage) {
case BTF_VAR_STATIC: return "static";
case BTF_VAR_GLOBAL_ALLOCATED: return "global";
case BTF_VAR_GLOBAL_EXTERN: return "extern";
default: return "unknown";
}
}
static int bpf_object__init_user_btf_map(struct bpf_object *obj,
const struct btf_type *sec,
int var_idx, int sec_idx,
const Elf_Data *data, bool strict,
const char *pin_root_path)
{
struct btf_map_def map_def = {}, inner_def = {};
const struct btf_type *var, *def;
const struct btf_var_secinfo *vi;
const struct btf_var *var_extra;
const char *map_name;
struct bpf_map *map;
int err;
vi = btf_var_secinfos(sec) + var_idx;
var = btf__type_by_id(obj->btf, vi->type);
var_extra = btf_var(var);
map_name = btf__name_by_offset(obj->btf, var->name_off);
if (map_name == NULL || map_name[0] == '\0') {
pr_warn("map #%d: empty name.\n", var_idx);
return -EINVAL;
}
if ((__u64)vi->offset + vi->size > data->d_size) {
pr_warn("map '%s' BTF data is corrupted.\n", map_name);
return -EINVAL;
}
if (!btf_is_var(var)) {
pr_warn("map '%s': unexpected var kind %s.\n",
map_name, btf_kind_str(var));
return -EINVAL;
}
if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
pr_warn("map '%s': unsupported map linkage %s.\n",
map_name, btf_var_linkage_str(var_extra->linkage));
return -EOPNOTSUPP;
}
def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
if (!btf_is_struct(def)) {
pr_warn("map '%s': unexpected def kind %s.\n",
map_name, btf_kind_str(var));
return -EINVAL;
}
if (def->size > vi->size) {
pr_warn("map '%s': invalid def size.\n", map_name);
return -EINVAL;
}
map = bpf_object__add_map(obj);
if (IS_ERR(map))
return PTR_ERR(map);
map->name = strdup(map_name);
if (!map->name) {
pr_warn("map '%s': failed to alloc map name.\n", map_name);
return -ENOMEM;
}
map->libbpf_type = LIBBPF_MAP_UNSPEC;
map->def.type = BPF_MAP_TYPE_UNSPEC;
map->sec_idx = sec_idx;
map->sec_offset = vi->offset;
map->btf_var_idx = var_idx;
pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
map_name, map->sec_idx, map->sec_offset);
err = parse_btf_map_def(map->name, obj->btf, def, strict, &map_def, &inner_def);
if (err)
return err;
fill_map_from_def(map, &map_def);
if (map_def.pinning == LIBBPF_PIN_BY_NAME) {
err = build_map_pin_path(map, pin_root_path);
if (err) {
pr_warn("map '%s': couldn't build pin path.\n", map->name);
return err;
}
}
if (map_def.parts & MAP_DEF_INNER_MAP) {
map->inner_map = calloc(1, sizeof(*map->inner_map));
if (!map->inner_map)
return -ENOMEM;
map->inner_map->fd = -1;
map->inner_map->sec_idx = sec_idx;
map->inner_map->name = malloc(strlen(map_name) + sizeof(".inner") + 1);
if (!map->inner_map->name)
return -ENOMEM;
sprintf(map->inner_map->name, "%s.inner", map_name);
fill_map_from_def(map->inner_map, &inner_def);
}
err = map_fill_btf_type_info(obj, map);
if (err)
return err;
return 0;
}
static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
const char *pin_root_path)
{
const struct btf_type *sec = NULL;
int nr_types, i, vlen, err;
const struct btf_type *t;
const char *name;
Elf_Data *data;
Elf_Scn *scn;
if (obj->efile.btf_maps_shndx < 0)
return 0;
scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
data = elf_sec_data(obj, scn);
if (!scn || !data) {
pr_warn("elf: failed to get %s map definitions for %s\n",
MAPS_ELF_SEC, obj->path);
return -EINVAL;
}
nr_types = btf__type_cnt(obj->btf);
for (i = 1; i < nr_types; i++) {
t = btf__type_by_id(obj->btf, i);
if (!btf_is_datasec(t))
continue;
name = btf__name_by_offset(obj->btf, t->name_off);
if (strcmp(name, MAPS_ELF_SEC) == 0) {
sec = t;
obj->efile.btf_maps_sec_btf_id = i;
break;
}
}
if (!sec) {
pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
return -ENOENT;
}
vlen = btf_vlen(sec);
for (i = 0; i < vlen; i++) {
err = bpf_object__init_user_btf_map(obj, sec, i,
obj->efile.btf_maps_shndx,
data, strict,
pin_root_path);
if (err)
return err;
}
return 0;
}
static int bpf_object__init_maps(struct bpf_object *obj,
const struct bpf_object_open_opts *opts)
{
const char *pin_root_path;
bool strict;
int err = 0;
strict = !OPTS_GET(opts, relaxed_maps, false);
pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
err = err ?: bpf_object__init_global_data_maps(obj);
err = err ?: bpf_object__init_kconfig_map(obj);
err = err ?: bpf_object__init_struct_ops_maps(obj);
return err;
}
static bool section_have_execinstr(struct bpf_object *obj, int idx)
{
Elf64_Shdr *sh;
sh = elf_sec_hdr(obj, elf_sec_by_idx(obj, idx));
if (!sh)
return false;
return sh->sh_flags & SHF_EXECINSTR;
}
static bool btf_needs_sanitization(struct bpf_object *obj)
{
bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
return !has_func || !has_datasec || !has_func_global || !has_float ||
!has_decl_tag || !has_type_tag || !has_enum64;
}
static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
{
bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
int enum64_placeholder_id = 0;
struct btf_type *t;
int i, j, vlen;
for (i = 1; i < btf__type_cnt(btf); i++) {
t = (struct btf_type *)btf__type_by_id(btf, i);
if ((!has_datasec && btf_is_var(t)) || (!has_decl_tag && btf_is_decl_tag(t))) {
/* replace VAR/DECL_TAG with INT */
t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
/*
* using size = 1 is the safest choice, 4 will be too
* big and cause kernel BTF validation failure if
* original variable took less than 4 bytes
*/
t->size = 1;
*(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
} else if (!has_datasec && btf_is_datasec(t)) {
/* replace DATASEC with STRUCT */
const struct btf_var_secinfo *v = btf_var_secinfos(t);
struct btf_member *m = btf_members(t);
struct btf_type *vt;
char *name;
name = (char *)btf__name_by_offset(btf, t->name_off);
while (*name) {
if (*name == '.')
*name = '_';
name++;
}
vlen = btf_vlen(t);
t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen);
for (j = 0; j < vlen; j++, v++, m++) {
/* order of field assignments is important */
m->offset = v->offset * 8;
m->type = v->type;
/* preserve variable name as member name */
vt = (void *)btf__type_by_id(btf, v->type);
m->name_off = vt->name_off;
}
} else if (!has_func && btf_is_func_proto(t)) {
/* replace FUNC_PROTO with ENUM */
vlen = btf_vlen(t);
t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen);
t->size = sizeof(__u32); /* kernel enforced */
} else if (!has_func && btf_is_func(t)) {
/* replace FUNC with TYPEDEF */
t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
} else if (!has_func_global && btf_is_func(t)) {
/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
} else if (!has_float && btf_is_float(t)) {
/* replace FLOAT with an equally-sized empty STRUCT;
* since C compilers do not accept e.g. "float" as a
* valid struct name, make it anonymous
*/
t->name_off = 0;
t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);
} else if (!has_type_tag && btf_is_type_tag(t)) {
/* replace TYPE_TAG with a CONST */
t->name_off = 0;
t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
} else if (!has_enum64 && btf_is_enum(t)) {
/* clear the kflag */
t->info = btf_type_info(btf_kind(t), btf_vlen(t), false);
} else if (!has_enum64 && btf_is_enum64(t)) {
/* replace ENUM64 with a union */
struct btf_member *m;
if (enum64_placeholder_id == 0) {
enum64_placeholder_id = btf__add_int(btf, "enum64_placeholder", 1, 0);
if (enum64_placeholder_id < 0)
return enum64_placeholder_id;
t = (struct btf_type *)btf__type_by_id(btf, i);
}
m = btf_members(t);
vlen = btf_vlen(t);
t->info = BTF_INFO_ENC(BTF_KIND_UNION, 0, vlen);
for (j = 0; j < vlen; j++, m++) {
m->type = enum64_placeholder_id;
m->offset = 0;
}
}
}
return 0;
}
static bool libbpf_needs_btf(const struct bpf_object *obj)
{
return obj->efile.btf_maps_shndx >= 0 ||
obj->efile.st_ops_shndx >= 0 ||
obj->nr_extern > 0;
}
static bool kernel_needs_btf(const struct bpf_object *obj)
{
return obj->efile.st_ops_shndx >= 0;
}
static int bpf_object__init_btf(struct bpf_object *obj,
Elf_Data *btf_data,
Elf_Data *btf_ext_data)
{
int err = -ENOENT;
if (btf_data) {
obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
err = libbpf_get_error(obj->btf);
if (err) {
obj->btf = NULL;
pr_warn("Error loading ELF section %s: %d.\n", BTF_ELF_SEC, err);
goto out;
}
/* enforce 8-byte pointers for BPF-targeted BTFs */
btf__set_pointer_size(obj->btf, 8);
}
if (btf_ext_data) {
struct btf_ext_info *ext_segs[3];
int seg_num, sec_num;
if (!obj->btf) {
pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
BTF_EXT_ELF_SEC, BTF_ELF_SEC);
goto out;
}
obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
err = libbpf_get_error(obj->btf_ext);
if (err) {
pr_warn("Error loading ELF section %s: %d. Ignored and continue.\n",
BTF_EXT_ELF_SEC, err);
obj->btf_ext = NULL;
goto out;
}
/* setup .BTF.ext to ELF section mapping */
ext_segs[0] = &obj->btf_ext->func_info;
ext_segs[1] = &obj->btf_ext->line_info;
ext_segs[2] = &obj->btf_ext->core_relo_info;
for (seg_num = 0; seg_num < ARRAY_SIZE(ext_segs); seg_num++) {
struct btf_ext_info *seg = ext_segs[seg_num];
const struct btf_ext_info_sec *sec;
const char *sec_name;
Elf_Scn *scn;
if (seg->sec_cnt == 0)
continue;
seg->sec_idxs = calloc(seg->sec_cnt, sizeof(*seg->sec_idxs));
if (!seg->sec_idxs) {
err = -ENOMEM;
goto out;
}
sec_num = 0;
for_each_btf_ext_sec(seg, sec) {
/* preventively increment index to avoid doing
* this before every continue below
*/
sec_num++;
sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
if (str_is_empty(sec_name))
continue;
scn = elf_sec_by_name(obj, sec_name);
if (!scn)
continue;
seg->sec_idxs[sec_num - 1] = elf_ndxscn(scn);
}
}
}
out:
if (err && libbpf_needs_btf(obj)) {
pr_warn("BTF is required, but is missing or corrupted.\n");
return err;
}
return 0;
}
static int compare_vsi_off(const void *_a, const void *_b)
{
const struct btf_var_secinfo *a = _a;
const struct btf_var_secinfo *b = _b;
return a->offset - b->offset;
}
static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
struct btf_type *t)
{
__u32 size = 0, i, vars = btf_vlen(t);
const char *sec_name = btf__name_by_offset(btf, t->name_off);
struct btf_var_secinfo *vsi;
bool fixup_offsets = false;
int err;
if (!sec_name) {
pr_debug("No name found in string section for DATASEC kind.\n");
return -ENOENT;
}
/* Extern-backing datasecs (.ksyms, .kconfig) have their size and
* variable offsets set at the previous step. Further, not every
* extern BTF VAR has corresponding ELF symbol preserved, so we skip
* all fixups altogether for such sections and go straight to sorting
* VARs within their DATASEC.
*/
if (strcmp(sec_name, KCONFIG_SEC) == 0 || strcmp(sec_name, KSYMS_SEC) == 0)
goto sort_vars;
/* Clang leaves DATASEC size and VAR offsets as zeroes, so we need to
* fix this up. But BPF static linker already fixes this up and fills
* all the sizes and offsets during static linking. So this step has
* to be optional. But the STV_HIDDEN handling is non-optional for any
* non-extern DATASEC, so the variable fixup loop below handles both
* functions at the same time, paying the cost of BTF VAR <-> ELF
* symbol matching just once.
*/
if (t->size == 0) {
err = find_elf_sec_sz(obj, sec_name, &size);
if (err || !size) {
pr_debug("sec '%s': failed to determine size from ELF: size %u, err %d\n",
sec_name, size, err);
return -ENOENT;
}
t->size = size;
fixup_offsets = true;
}
for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
const struct btf_type *t_var;
struct btf_var *var;
const char *var_name;
Elf64_Sym *sym;
t_var = btf__type_by_id(btf, vsi->type);
if (!t_var || !btf_is_var(t_var)) {
pr_debug("sec '%s': unexpected non-VAR type found\n", sec_name);
return -EINVAL;
}
var = btf_var(t_var);
if (var->linkage == BTF_VAR_STATIC || var->linkage == BTF_VAR_GLOBAL_EXTERN)
continue;
var_name = btf__name_by_offset(btf, t_var->name_off);
if (!var_name) {
pr_debug("sec '%s': failed to find name of DATASEC's member #%d\n",
sec_name, i);
return -ENOENT;
}
sym = find_elf_var_sym(obj, var_name);
if (IS_ERR(sym)) {
pr_debug("sec '%s': failed to find ELF symbol for VAR '%s'\n",
sec_name, var_name);
return -ENOENT;
}
if (fixup_offsets)
vsi->offset = sym->st_value;
/* if variable is a global/weak symbol, but has restricted
* (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF VAR
* as static. This follows similar logic for functions (BPF
* subprogs) and influences libbpf's further decisions about
* whether to make global data BPF array maps as
* BPF_F_MMAPABLE.
*/
if (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
|| ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL)
var->linkage = BTF_VAR_STATIC;
}
sort_vars:
qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
return 0;
}
static int bpf_object_fixup_btf(struct bpf_object *obj)
{
int i, n, err = 0;
if (!obj->btf)
return 0;
n = btf__type_cnt(obj->btf);
for (i = 1; i < n; i++) {
struct btf_type *t = btf_type_by_id(obj->btf, i);
/* Loader needs to fix up some of the things compiler
* couldn't get its hands on while emitting BTF. This
* is section size and global variable offset. We use
* the info from the ELF itself for this purpose.
*/
if (btf_is_datasec(t)) {
err = btf_fixup_datasec(obj, obj->btf, t);
if (err)
return err;
}
}
return 0;
}
static bool prog_needs_vmlinux_btf(struct bpf_program *prog)
{
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
prog->type == BPF_PROG_TYPE_LSM)
return true;
/* BPF_PROG_TYPE_TRACING programs which do not attach to other programs
* also need vmlinux BTF
*/
if (prog->type == BPF_PROG_TYPE_TRACING && !prog->attach_prog_fd)
return true;
return false;
}
static bool obj_needs_vmlinux_btf(const struct bpf_object *obj)
{
struct bpf_program *prog;
int i;
/* CO-RE relocations need kernel BTF, only when btf_custom_path
* is not specified
*/
if (obj->btf_ext && obj->btf_ext->core_relo_info.len && !obj->btf_custom_path)
return true;
/* Support for typed ksyms needs kernel BTF */
for (i = 0; i < obj->nr_extern; i++) {
const struct extern_desc *ext;
ext = &obj->externs[i];
if (ext->type == EXT_KSYM && ext->ksym.type_id)
return true;
}
bpf_object__for_each_program(prog, obj) {
if (!prog->autoload)
continue;
if (prog_needs_vmlinux_btf(prog))
return true;
}
return false;
}
static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force)
{
int err;
/* btf_vmlinux could be loaded earlier */
if (obj->btf_vmlinux || obj->gen_loader)
return 0;
if (!force && !obj_needs_vmlinux_btf(obj))
return 0;
obj->btf_vmlinux = btf__load_vmlinux_btf();
err = libbpf_get_error(obj->btf_vmlinux);
if (err) {
pr_warn("Error loading vmlinux BTF: %d\n", err);
obj->btf_vmlinux = NULL;
return err;
}
return 0;
}
static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
{
struct btf *kern_btf = obj->btf;
bool btf_mandatory, sanitize;
int i, err = 0;
if (!obj->btf)
return 0;
if (!kernel_supports(obj, FEAT_BTF)) {
if (kernel_needs_btf(obj)) {
err = -EOPNOTSUPP;
goto report;
}
pr_debug("Kernel doesn't support BTF, skipping uploading it.\n");
return 0;
}
/* Even though some subprogs are global/weak, user might prefer more
* permissive BPF verification process that BPF verifier performs for
* static functions, taking into account more context from the caller
* functions. In such case, they need to mark such subprogs with
* __attribute__((visibility("hidden"))) and libbpf will adjust
* corresponding FUNC BTF type to be marked as static and trigger more
* involved BPF verification process.
*/
for (i = 0; i < obj->nr_programs; i++) {
struct bpf_program *prog = &obj->programs[i];
struct btf_type *t;
const char *name;
int j, n;
if (!prog->mark_btf_static || !prog_is_subprog(obj, prog))
continue;
n = btf__type_cnt(obj->btf);
for (j = 1; j < n; j++) {
t = btf_type_by_id(obj->btf, j);
if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL)
continue;
name = btf__str_by_offset(obj->btf, t->name_off);
if (strcmp(name, prog->name) != 0)
continue;
t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_STATIC, 0);
break;
}
}
sanitize = btf_needs_sanitization(obj);
if (sanitize) {
const void *raw_data;
__u32 sz;
/* clone BTF to sanitize a copy and leave the original intact */
raw_data = btf__raw_data(obj->btf, &sz);
kern_btf = btf__new(raw_data, sz);
err = libbpf_get_error(kern_btf);
if (err)
return err;
/* enforce 8-byte pointers for BPF-targeted BTFs */
btf__set_pointer_size(obj->btf, 8);
err = bpf_object__sanitize_btf(obj, kern_btf);
if (err)
return err;
}
if (obj->gen_loader) {
__u32 raw_size = 0;
const void *raw_data = btf__raw_data(kern_btf, &raw_size);
if (!raw_data)
return -ENOMEM;
bpf_gen__load_btf(obj->gen_loader, raw_data, raw_size);
/* Pretend to have valid FD to pass various fd >= 0 checks.
* This fd == 0 will not be used with any syscall and will be reset to -1 eventually.
*/
btf__set_fd(kern_btf, 0);
} else {
/* currently BPF_BTF_LOAD only supports log_level 1 */
err = btf_load_into_kernel(kern_btf, obj->log_buf, obj->log_size,
obj->log_level ? 1 : 0);
}
if (sanitize) {
if (!err) {
/* move fd to libbpf's BTF */
btf__set_fd(obj->btf, btf__fd(kern_btf));
btf__set_fd(kern_btf, -1);
}
btf__free(kern_btf);
}
report:
if (err) {
btf_mandatory = kernel_needs_btf(obj);
pr_warn("Error loading .BTF into kernel: %d. %s\n", err,
btf_mandatory ? "BTF is mandatory, can't proceed."
: "BTF is optional, ignoring.");
if (!btf_mandatory)
err = 0;
}
return err;
}
static const char *elf_sym_str(const struct bpf_object *obj, size_t off)
{
const char *name;
name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, off);
if (!name) {
pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
off, obj->path, elf_errmsg(-1));
return NULL;
}
return name;
}
static const char *elf_sec_str(const struct bpf_object *obj, size_t off)
{
const char *name;
name = elf_strptr(obj->efile.elf, obj->efile.shstrndx, off);
if (!name) {
pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
off, obj->path, elf_errmsg(-1));
return NULL;
}
return name;
}
static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx)
{
Elf_Scn *scn;
scn = elf_getscn(obj->efile.elf, idx);
if (!scn) {
pr_warn("elf: failed to get section(%zu) from %s: %s\n",
idx, obj->path, elf_errmsg(-1));
return NULL;
}
return scn;
}
static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name)
{
Elf_Scn *scn = NULL;
Elf *elf = obj->efile.elf;
const char *sec_name;
while ((scn = elf_nextscn(elf, scn)) != NULL) {
sec_name = elf_sec_name(obj, scn);
if (!sec_name)
return NULL;
if (strcmp(sec_name, name) != 0)
continue;
return scn;
}
return NULL;
}
static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn)
{
Elf64_Shdr *shdr;
if (!scn)
return NULL;
shdr = elf64_getshdr(scn);
if (!shdr) {
pr_warn("elf: failed to get section(%zu) header from %s: %s\n",
elf_ndxscn(scn), obj->path, elf_errmsg(-1));
return NULL;
}
return shdr;
}
static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn)
{
const char *name;
Elf64_Shdr *sh;
if (!scn)
return NULL;
sh = elf_sec_hdr(obj, scn);
if (!sh)
return NULL;
name = elf_sec_str(obj, sh->sh_name);
if (!name) {
pr_warn("elf: failed to get section(%zu) name from %s: %s\n",
elf_ndxscn(scn), obj->path, elf_errmsg(-1));
return NULL;
}
return name;
}
static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
{
Elf_Data *data;
if (!scn)
return NULL;
data = elf_getdata(scn, 0);
if (!data) {
pr_warn("elf: failed to get section(%zu) %s data from %s: %s\n",
elf_ndxscn(scn), elf_sec_name(obj, scn) ?: "<?>",
obj->path, elf_errmsg(-1));
return NULL;
}
return data;
}
static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx)
{
if (idx >= obj->efile.symbols->d_size / sizeof(Elf64_Sym))
return NULL;
return (Elf64_Sym *)obj->efile.symbols->d_buf + idx;
}
static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx)
{
if (idx >= data->d_size / sizeof(Elf64_Rel))
return NULL;
return (Elf64_Rel *)data->d_buf + idx;
}
static bool is_sec_name_dwarf(const char *name)
{
/* approximation, but the actual list is too long */
return str_has_pfx(name, ".debug_");
}
static bool ignore_elf_section(Elf64_Shdr *hdr, const char *name)
{
/* no special handling of .strtab */
if (hdr->sh_type == SHT_STRTAB)
return true;
/* ignore .llvm_addrsig section as well */
if (hdr->sh_type == SHT_LLVM_ADDRSIG)
return true;
/* no subprograms will lead to an empty .text section, ignore it */
if (hdr->sh_type == SHT_PROGBITS && hdr->sh_size == 0 &&
strcmp(name, ".text") == 0)
return true;
/* DWARF sections */
if (is_sec_name_dwarf(name))
return true;
if (str_has_pfx(name, ".rel")) {
name += sizeof(".rel") - 1;
/* DWARF section relocations */
if (is_sec_name_dwarf(name))
return true;
/* .BTF and .BTF.ext don't need relocations */
if (strcmp(name, BTF_ELF_SEC) == 0 ||
strcmp(name, BTF_EXT_ELF_SEC) == 0)
return true;
}
return false;
}
static int cmp_progs(const void *_a, const void *_b)
{
const struct bpf_program *a = _a;
const struct bpf_program *b = _b;
if (a->sec_idx != b->sec_idx)
return a->sec_idx < b->sec_idx ? -1 : 1;
/* sec_insn_off can't be the same within the section */
return a->sec_insn_off < b->sec_insn_off ? -1 : 1;
}
static int bpf_object__elf_collect(struct bpf_object *obj)
{
struct elf_sec_desc *sec_desc;
Elf *elf = obj->efile.elf;
Elf_Data *btf_ext_data = NULL;
Elf_Data *btf_data = NULL;
int idx = 0, err = 0;
const char *name;
Elf_Data *data;
Elf_Scn *scn;
Elf64_Shdr *sh;
/* ELF section indices are 0-based, but sec #0 is special "invalid"
* section. Since section count retrieved by elf_getshdrnum() does
* include sec #0, it is already the necessary size of an array to keep
* all the sections.
*/
if (elf_getshdrnum(obj->efile.elf, &obj->efile.sec_cnt)) {
pr_warn("elf: failed to get the number of sections for %s: %s\n",
obj->path, elf_errmsg(-1));
return -LIBBPF_ERRNO__FORMAT;
}
obj->efile.secs = calloc(obj->efile.sec_cnt, sizeof(*obj->efile.secs));
if (!obj->efile.secs)
return -ENOMEM;
/* a bunch of ELF parsing functionality depends on processing symbols,
* so do the first pass and find the symbol table
*/
scn = NULL;
while ((scn = elf_nextscn(elf, scn)) != NULL) {
sh = elf_sec_hdr(obj, scn);
if (!sh)
return -LIBBPF_ERRNO__FORMAT;
if (sh->sh_type == SHT_SYMTAB) {
if (obj->efile.symbols) {
pr_warn("elf: multiple symbol tables in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
data = elf_sec_data(obj, scn);
if (!data)
return -LIBBPF_ERRNO__FORMAT;
idx = elf_ndxscn(scn);
obj->efile.symbols = data;
obj->efile.symbols_shndx = idx;
obj->efile.strtabidx = sh->sh_link;
}
}
if (!obj->efile.symbols) {
pr_warn("elf: couldn't find symbol table in %s, stripped object file?\n",
obj->path);
return -ENOENT;
}
scn = NULL;
while ((scn = elf_nextscn(elf, scn)) != NULL) {
idx = elf_ndxscn(scn);
sec_desc = &obj->efile.secs[idx];
sh = elf_sec_hdr(obj, scn);
if (!sh)
return -LIBBPF_ERRNO__FORMAT;
name = elf_sec_str(obj, sh->sh_name);
if (!name)
return -LIBBPF_ERRNO__FORMAT;
if (ignore_elf_section(sh, name))
continue;
data = elf_sec_data(obj, scn);
if (!data)
return -LIBBPF_ERRNO__FORMAT;
pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
idx, name, (unsigned long)data->d_size,
(int)sh->sh_link, (unsigned long)sh->sh_flags,
(int)sh->sh_type);
if (strcmp(name, "license") == 0) {
err = bpf_object__init_license(obj, data->d_buf, data->d_size);
if (err)
return err;
} else if (strcmp(name, "version") == 0) {
err = bpf_object__init_kversion(obj, data->d_buf, data->d_size);
if (err)
return err;
} else if (strcmp(name, "maps") == 0) {
pr_warn("elf: legacy map definitions in 'maps' section are not supported by libbpf v1.0+\n");
return -ENOTSUP;
} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
obj->efile.btf_maps_shndx = idx;
} else if (strcmp(name, BTF_ELF_SEC) == 0) {
if (sh->sh_type != SHT_PROGBITS)
return -LIBBPF_ERRNO__FORMAT;
btf_data = data;
} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
if (sh->sh_type != SHT_PROGBITS)
return -LIBBPF_ERRNO__FORMAT;
btf_ext_data = data;
} else if (sh->sh_type == SHT_SYMTAB) {
/* already processed during the first pass above */
} else if (sh->sh_type == SHT_PROGBITS && data->d_size > 0) {
if (sh->sh_flags & SHF_EXECINSTR) {
if (strcmp(name, ".text") == 0)
obj->efile.text_shndx = idx;
err = bpf_object__add_programs(obj, data, name, idx);
if (err)
return err;
} else if (strcmp(name, DATA_SEC) == 0 ||
str_has_pfx(name, DATA_SEC ".")) {
sec_desc->sec_type = SEC_DATA;
sec_desc->shdr = sh;
sec_desc->data = data;
} else if (strcmp(name, RODATA_SEC) == 0 ||
str_has_pfx(name, RODATA_SEC ".")) {
sec_desc->sec_type = SEC_RODATA;
sec_desc->shdr = sh;
sec_desc->data = data;
} else if (strcmp(name, STRUCT_OPS_SEC) == 0) {
obj->efile.st_ops_data = data;
obj->efile.st_ops_shndx = idx;
} else {
pr_info("elf: skipping unrecognized data section(%d) %s\n",
idx, name);
}
} else if (sh->sh_type == SHT_REL) {
int targ_sec_idx = sh->sh_info; /* points to other section */
if (sh->sh_entsize != sizeof(Elf64_Rel) ||
targ_sec_idx >= obj->efile.sec_cnt)
return -LIBBPF_ERRNO__FORMAT;
/* Only do relo for section with exec instructions */
if (!section_have_execinstr(obj, targ_sec_idx) &&
strcmp(name, ".rel" STRUCT_OPS_SEC) &&
strcmp(name, ".rel" MAPS_ELF_SEC)) {
pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n",
idx, name, targ_sec_idx,
elf_sec_name(obj, elf_sec_by_idx(obj, targ_sec_idx)) ?: "<?>");
continue;
}
sec_desc->sec_type = SEC_RELO;
sec_desc->shdr = sh;
sec_desc->data = data;
} else if (sh->sh_type == SHT_NOBITS && (strcmp(name, BSS_SEC) == 0 ||
str_has_pfx(name, BSS_SEC "."))) {
sec_desc->sec_type = SEC_BSS;
sec_desc->shdr = sh;
sec_desc->data = data;
} else {
pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name,
(size_t)sh->sh_size);
}
}
if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
pr_warn("elf: symbol strings section missing or invalid in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
/* sort BPF programs by section name and in-section instruction offset
* for faster search
*/
if (obj->nr_programs)
qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs);
return bpf_object__init_btf(obj, btf_data, btf_ext_data);
}
static bool sym_is_extern(const Elf64_Sym *sym)
{
int bind = ELF64_ST_BIND(sym->st_info);
/* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
return sym->st_shndx == SHN_UNDEF &&
(bind == STB_GLOBAL || bind == STB_WEAK) &&
ELF64_ST_TYPE(sym->st_info) == STT_NOTYPE;
}
static bool sym_is_subprog(const Elf64_Sym *sym, int text_shndx)
{
int bind = ELF64_ST_BIND(sym->st_info);
int type = ELF64_ST_TYPE(sym->st_info);
/* in .text section */
if (sym->st_shndx != text_shndx)
return false;
/* local function */
if (bind == STB_LOCAL && type == STT_SECTION)
return true;
/* global function */
return bind == STB_GLOBAL && type == STT_FUNC;
}
static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
{
const struct btf_type *t;
const char *tname;
int i, n;
if (!btf)
return -ESRCH;
n = btf__type_cnt(btf);
for (i = 1; i < n; i++) {
t = btf__type_by_id(btf, i);
if (!btf_is_var(t) && !btf_is_func(t))
continue;
tname = btf__name_by_offset(btf, t->name_off);
if (strcmp(tname, ext_name))
continue;
if (btf_is_var(t) &&
btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
return -EINVAL;
if (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN)
return -EINVAL;
return i;
}
return -ENOENT;
}
static int find_extern_sec_btf_id(struct btf *btf, int ext_btf_id) {
const struct btf_var_secinfo *vs;
const struct btf_type *t;
int i, j, n;
if (!btf)
return -ESRCH;
n = btf__type_cnt(btf);
for (i = 1; i < n; i++) {
t = btf__type_by_id(btf, i);
if (!btf_is_datasec(t))
continue;
vs = btf_var_secinfos(t);
for (j = 0; j < btf_vlen(t); j++, vs++) {
if (vs->type == ext_btf_id)
return i;
}
}
return -ENOENT;
}
static enum kcfg_type find_kcfg_type(const struct btf *btf, int id,
bool *is_signed)
{
const struct btf_type *t;
const char *name;
t = skip_mods_and_typedefs(btf, id, NULL);
name = btf__name_by_offset(btf, t->name_off);
if (is_signed)
*is_signed = false;
switch (btf_kind(t)) {
case BTF_KIND_INT: {
int enc = btf_int_encoding(t);
if (enc & BTF_INT_BOOL)
return t->size == 1 ? KCFG_BOOL : KCFG_UNKNOWN;
if (is_signed)
*is_signed = enc & BTF_INT_SIGNED;
if (t->size == 1)
return KCFG_CHAR;
if (t->size < 1 || t->size > 8 || (t->size & (t->size - 1)))
return KCFG_UNKNOWN;
return KCFG_INT;
}
case BTF_KIND_ENUM:
if (t->size != 4)
return KCFG_UNKNOWN;
if (strcmp(name, "libbpf_tristate"))
return KCFG_UNKNOWN;
return KCFG_TRISTATE;
case BTF_KIND_ENUM64:
if (strcmp(name, "libbpf_tristate"))
return KCFG_UNKNOWN;
return KCFG_TRISTATE;
case BTF_KIND_ARRAY:
if (btf_array(t)->nelems == 0)
return KCFG_UNKNOWN;
if (find_kcfg_type(btf, btf_array(t)->type, NULL) != KCFG_CHAR)
return KCFG_UNKNOWN;
return KCFG_CHAR_ARR;
default:
return KCFG_UNKNOWN;
}
}
static int cmp_externs(const void *_a, const void *_b)
{
const struct extern_desc *a = _a;
const struct extern_desc *b = _b;
if (a->type != b->type)
return a->type < b->type ? -1 : 1;
if (a->type == EXT_KCFG) {
/* descending order by alignment requirements */
if (a->kcfg.align != b->kcfg.align)
return a->kcfg.align > b->kcfg.align ? -1 : 1;
/* ascending order by size, within same alignment class */
if (a->kcfg.sz != b->kcfg.sz)
return a->kcfg.sz < b->kcfg.sz ? -1 : 1;
}
/* resolve ties by name */
return strcmp(a->name, b->name);
}
static int find_int_btf_id(const struct btf *btf)
{
const struct btf_type *t;
int i, n;
n = btf__type_cnt(btf);
for (i = 1; i < n; i++) {
t = btf__type_by_id(btf, i);
if (btf_is_int(t) && btf_int_bits(t) == 32)
return i;
}
return 0;
}
static int add_dummy_ksym_var(struct btf *btf)
{
int i, int_btf_id, sec_btf_id, dummy_var_btf_id;
const struct btf_var_secinfo *vs;
const struct btf_type *sec;
if (!btf)
return 0;
sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
BTF_KIND_DATASEC);
if (sec_btf_id < 0)
return 0;
sec = btf__type_by_id(btf, sec_btf_id);
vs = btf_var_secinfos(sec);
for (i = 0; i < btf_vlen(sec); i++, vs++) {
const struct btf_type *vt;
vt = btf__type_by_id(btf, vs->type);
if (btf_is_func(vt))
break;
}
/* No func in ksyms sec. No need to add dummy var. */
if (i == btf_vlen(sec))
return 0;
int_btf_id = find_int_btf_id(btf);
dummy_var_btf_id = btf__add_var(btf,
"dummy_ksym",
BTF_VAR_GLOBAL_ALLOCATED,
int_btf_id);
if (dummy_var_btf_id < 0)
pr_warn("cannot create a dummy_ksym var\n");
return dummy_var_btf_id;
}
static int bpf_object__collect_externs(struct bpf_object *obj)
{
struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL;
const struct btf_type *t;
struct extern_desc *ext;
int i, n, off, dummy_var_btf_id;
const char *ext_name, *sec_name;
Elf_Scn *scn;
Elf64_Shdr *sh;
if (!obj->efile.symbols)
return 0;
scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx);
sh = elf_sec_hdr(obj, scn);
if (!sh || sh->sh_entsize != sizeof(Elf64_Sym))
return -LIBBPF_ERRNO__FORMAT;
dummy_var_btf_id = add_dummy_ksym_var(obj->btf);
if (dummy_var_btf_id < 0)
return dummy_var_btf_id;
n = sh->sh_size / sh->sh_entsize;
pr_debug("looking for externs among %d symbols...\n", n);
for (i = 0; i < n; i++) {
Elf64_Sym *sym = elf_sym_by_idx(obj, i);
if (!sym)
return -LIBBPF_ERRNO__FORMAT;
if (!sym_is_extern(sym))
continue;
ext_name = elf_sym_str(obj, sym->st_name);
if (!ext_name || !ext_name[0])
continue;
ext = obj->externs;
ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
if (!ext)
return -ENOMEM;
obj->externs = ext;
ext = &ext[obj->nr_extern];
memset(ext, 0, sizeof(*ext));
obj->nr_extern++;
ext->btf_id = find_extern_btf_id(obj->btf, ext_name);
if (ext->btf_id <= 0) {
pr_warn("failed to find BTF for extern '%s': %d\n",
ext_name, ext->btf_id);
return ext->btf_id;
}
t = btf__type_by_id(obj->btf, ext->btf_id);
ext->name = btf__name_by_offset(obj->btf, t->name_off);
ext->sym_idx = i;
ext->is_weak = ELF64_ST_BIND(sym->st_info) == STB_WEAK;
ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id);
if (ext->sec_btf_id <= 0) {
pr_warn("failed to find BTF for extern '%s' [%d] section: %d\n",
ext_name, ext->btf_id, ext->sec_btf_id);
return ext->sec_btf_id;
}
sec = (void *)btf__type_by_id(obj->btf, ext->sec_btf_id);
sec_name = btf__name_by_offset(obj->btf, sec->name_off);
if (strcmp(sec_name, KCONFIG_SEC) == 0) {
if (btf_is_func(t)) {
pr_warn("extern function %s is unsupported under %s section\n",
ext->name, KCONFIG_SEC);
return -ENOTSUP;
}
kcfg_sec = sec;
ext->type = EXT_KCFG;
ext->kcfg.sz = btf__resolve_size(obj->btf, t->type);
if (ext->kcfg.sz <= 0) {
pr_warn("failed to resolve size of extern (kcfg) '%s': %d\n",
ext_name, ext->kcfg.sz);
return ext->kcfg.sz;
}
ext->kcfg.align = btf__align_of(obj->btf, t->type);
if (ext->kcfg.align <= 0) {
pr_warn("failed to determine alignment of extern (kcfg) '%s': %d\n",
ext_name, ext->kcfg.align);
return -EINVAL;
}
ext->kcfg.type = find_kcfg_type(obj->btf, t->type,
&ext->kcfg.is_signed);
if (ext->kcfg.type == KCFG_UNKNOWN) {
pr_warn("extern (kcfg) '%s': type is unsupported\n", ext_name);
return -ENOTSUP;
}
} else if (strcmp(sec_name, KSYMS_SEC) == 0) {
ksym_sec = sec;
ext->type = EXT_KSYM;
skip_mods_and_typedefs(obj->btf, t->type,
&ext->ksym.type_id);
} else {
pr_warn("unrecognized extern section '%s'\n", sec_name);
return -ENOTSUP;
}
}
pr_debug("collected %d externs total\n", obj->nr_extern);
if (!obj->nr_extern)
return 0;
/* sort externs by type, for kcfg ones also by (align, size, name) */
qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs);
/* for .ksyms section, we need to turn all externs into allocated
* variables in BTF to pass kernel verification; we do this by
* pretending that each extern is a 8-byte variable
*/
if (ksym_sec) {
/* find existing 4-byte integer type in BTF to use for fake
* extern variables in DATASEC
*/
int int_btf_id = find_int_btf_id(obj->btf);
/* For extern function, a dummy_var added earlier
* will be used to replace the vs->type and
* its name string will be used to refill
* the missing param's name.
*/
const struct btf_type *dummy_var;
dummy_var = btf__type_by_id(obj->btf, dummy_var_btf_id);
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type != EXT_KSYM)
continue;
pr_debug("extern (ksym) #%d: symbol %d, name %s\n",
i, ext->sym_idx, ext->name);
}
sec = ksym_sec;
n = btf_vlen(sec);
for (i = 0, off = 0; i < n; i++, off += sizeof(int)) {
struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
struct btf_type *vt;
vt = (void *)btf__type_by_id(obj->btf, vs->type);
ext_name = btf__name_by_offset(obj->btf, vt->name_off);
ext = find_extern_by_name(obj, ext_name);
if (!ext) {
pr_warn("failed to find extern definition for BTF %s '%s'\n",
btf_kind_str(vt), ext_name);
return -ESRCH;
}
if (btf_is_func(vt)) {
const struct btf_type *func_proto;
struct btf_param *param;
int j;
func_proto = btf__type_by_id(obj->btf,
vt->type);
param = btf_params(func_proto);
/* Reuse the dummy_var string if the
* func proto does not have param name.
*/
for (j = 0; j < btf_vlen(func_proto); j++)
if (param[j].type && !param[j].name_off)
param[j].name_off =
dummy_var->name_off;
vs->type = dummy_var_btf_id;
vt->info &= ~0xffff;
vt->info |= BTF_FUNC_GLOBAL;
} else {
btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
vt->type = int_btf_id;
}
vs->offset = off;
vs->size = sizeof(int);
}
sec->size = off;
}
if (kcfg_sec) {
sec = kcfg_sec;
/* for kcfg externs calculate their offsets within a .kconfig map */
off = 0;
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type != EXT_KCFG)
continue;
ext->kcfg.data_off = roundup(off, ext->kcfg.align);
off = ext->kcfg.data_off + ext->kcfg.sz;
pr_debug("extern (kcfg) #%d: symbol %d, off %u, name %s\n",
i, ext->sym_idx, ext->kcfg.data_off, ext->name);
}
sec->size = off;
n = btf_vlen(sec);
for (i = 0; i < n; i++) {
struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
t = btf__type_by_id(obj->btf, vs->type);
ext_name = btf__name_by_offset(obj->btf, t->name_off);
ext = find_extern_by_name(obj, ext_name);
if (!ext) {
pr_warn("failed to find extern definition for BTF var '%s'\n",
ext_name);
return -ESRCH;
}
btf_var(t)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
vs->offset = ext->kcfg.data_off;
}
}
return 0;
}
static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog)
{
return prog->sec_idx == obj->efile.text_shndx && obj->nr_programs > 1;
}
struct bpf_program *
bpf_object__find_program_by_name(const struct bpf_object *obj,
const char *name)
{
struct bpf_program *prog;
bpf_object__for_each_program(prog, obj) {
if (prog_is_subprog(obj, prog))
continue;
if (!strcmp(prog->name, name))
return prog;
}
return errno = ENOENT, NULL;
}
static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
int shndx)
{
switch (obj->efile.secs[shndx].sec_type) {
case SEC_BSS:
case SEC_DATA:
case SEC_RODATA:
return true;
default:
return false;
}
}
static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
int shndx)
{
return shndx == obj->efile.btf_maps_shndx;
}
static enum libbpf_map_type
bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
{
if (shndx == obj->efile.symbols_shndx)
return LIBBPF_MAP_KCONFIG;
switch (obj->efile.secs[shndx].sec_type) {
case SEC_BSS:
return LIBBPF_MAP_BSS;
case SEC_DATA:
return LIBBPF_MAP_DATA;
case SEC_RODATA:
return LIBBPF_MAP_RODATA;
default:
return LIBBPF_MAP_UNSPEC;
}
}
static int bpf_program__record_reloc(struct bpf_program *prog,
struct reloc_desc *reloc_desc,
__u32 insn_idx, const char *sym_name,
const Elf64_Sym *sym, const Elf64_Rel *rel)
{
struct bpf_insn *insn = &prog->insns[insn_idx];
size_t map_idx, nr_maps = prog->obj->nr_maps;
struct bpf_object *obj = prog->obj;
__u32 shdr_idx = sym->st_shndx;
enum libbpf_map_type type;
const char *sym_sec_name;
struct bpf_map *map;
if (!is_call_insn(insn) && !is_ldimm64_insn(insn)) {
pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
prog->name, sym_name, insn_idx, insn->code);
return -LIBBPF_ERRNO__RELOC;
}
if (sym_is_extern(sym)) {
int sym_idx = ELF64_R_SYM(rel->r_info);
int i, n = obj->nr_extern;
struct extern_desc *ext;
for (i = 0; i < n; i++) {
ext = &obj->externs[i];
if (ext->sym_idx == sym_idx)
break;
}
if (i >= n) {
pr_warn("prog '%s': extern relo failed to find extern for '%s' (%d)\n",
prog->name, sym_name, sym_idx);
return -LIBBPF_ERRNO__RELOC;
}
pr_debug("prog '%s': found extern #%d '%s' (sym %d) for insn #%u\n",
prog->name, i, ext->name, ext->sym_idx, insn_idx);
if (insn->code == (BPF_JMP | BPF_CALL))
reloc_desc->type = RELO_EXTERN_FUNC;
else
reloc_desc->type = RELO_EXTERN_VAR;
reloc_desc->insn_idx = insn_idx;
reloc_desc->sym_off = i; /* sym_off stores extern index */
return 0;
}
/* sub-program call relocation */
if (is_call_insn(insn)) {
if (insn->src_reg != BPF_PSEUDO_CALL) {
pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
return -LIBBPF_ERRNO__RELOC;
}
/* text_shndx can be 0, if no default "main" program exists */
if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
prog->name, sym_name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
if (sym->st_value % BPF_INSN_SZ) {
pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
prog->name, sym_name, (size_t)sym->st_value);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_CALL;
reloc_desc->insn_idx = insn_idx;
reloc_desc->sym_off = sym->st_value;
return 0;
}
if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n",
prog->name, sym_name, shdr_idx);
return -LIBBPF_ERRNO__RELOC;
}
/* loading subprog addresses */
if (sym_is_subprog(sym, obj->efile.text_shndx)) {
/* global_func: sym->st_value = offset in the section, insn->imm = 0.
* local_func: sym->st_value = 0, insn->imm = offset in the section.
*/
if ((sym->st_value % BPF_INSN_SZ) || (insn->imm % BPF_INSN_SZ)) {
pr_warn("prog '%s': bad subprog addr relo against '%s' at offset %zu+%d\n",
prog->name, sym_name, (size_t)sym->st_value, insn->imm);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_SUBPROG_ADDR;
reloc_desc->insn_idx = insn_idx;
reloc_desc->sym_off = sym->st_value;
return 0;
}
type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
/* generic map reference relocation */
if (type == LIBBPF_MAP_UNSPEC) {
if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
pr_warn("prog '%s': bad map relo against '%s' in section '%s'\n",
prog->name, sym_name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
for (map_idx = 0; map_idx < nr_maps; map_idx++) {
map = &obj->maps[map_idx];
if (map->libbpf_type != type ||
map->sec_idx != sym->st_shndx ||
map->sec_offset != sym->st_value)
continue;
pr_debug("prog '%s': found map %zd (%s, sec %d, off %zu) for insn #%u\n",
prog->name, map_idx, map->name, map->sec_idx,
map->sec_offset, insn_idx);
break;
}
if (map_idx >= nr_maps) {
pr_warn("prog '%s': map relo failed to find map for section '%s', off %zu\n",
prog->name, sym_sec_name, (size_t)sym->st_value);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_LD64;
reloc_desc->insn_idx = insn_idx;
reloc_desc->map_idx = map_idx;
reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */
return 0;
}
/* global data map relocation */
if (!bpf_object__shndx_is_data(obj, shdr_idx)) {
pr_warn("prog '%s': bad data relo against section '%s'\n",
prog->name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
for (map_idx = 0; map_idx < nr_maps; map_idx++) {
map = &obj->maps[map_idx];
if (map->libbpf_type != type || map->sec_idx != sym->st_shndx)
continue;
pr_debug("prog '%s': found data map %zd (%s, sec %d, off %zu) for insn %u\n",
prog->name, map_idx, map->name, map->sec_idx,
map->sec_offset, insn_idx);
break;
}
if (map_idx >= nr_maps) {
pr_warn("prog '%s': data relo failed to find map for section '%s'\n",
prog->name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_DATA;
reloc_desc->insn_idx = insn_idx;
reloc_desc->map_idx = map_idx;
reloc_desc->sym_off = sym->st_value;
return 0;
}
static bool prog_contains_insn(const struct bpf_program *prog, size_t insn_idx)
{
return insn_idx >= prog->sec_insn_off &&
insn_idx < prog->sec_insn_off + prog->sec_insn_cnt;
}
static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
size_t sec_idx, size_t insn_idx)
{
int l = 0, r = obj->nr_programs - 1, m;
struct bpf_program *prog;
if (!obj->nr_programs)
return NULL;
while (l < r) {
m = l + (r - l + 1) / 2;
prog = &obj->programs[m];
if (prog->sec_idx < sec_idx ||
(prog->sec_idx == sec_idx && prog->sec_insn_off <= insn_idx))
l = m;
else
r = m - 1;
}
/* matching program could be at index l, but it still might be the
* wrong one, so we need to double check conditions for the last time
*/
prog = &obj->programs[l];
if (prog->sec_idx == sec_idx && prog_contains_insn(prog, insn_idx))
return prog;
return NULL;
}
static int
bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Data *data)
{
const char *relo_sec_name, *sec_name;
size_t sec_idx = shdr->sh_info, sym_idx;
struct bpf_program *prog;
struct reloc_desc *relos;
int err, i, nrels;
const char *sym_name;
__u32 insn_idx;
Elf_Scn *scn;
Elf_Data *scn_data;
Elf64_Sym *sym;
Elf64_Rel *rel;
if (sec_idx >= obj->efile.sec_cnt)
return -EINVAL;
scn = elf_sec_by_idx(obj, sec_idx);
scn_data = elf_sec_data(obj, scn);
relo_sec_name = elf_sec_str(obj, shdr->sh_name);
sec_name = elf_sec_name(obj, scn);
if (!relo_sec_name || !sec_name)
return -EINVAL;
pr_debug("sec '%s': collecting relocation for section(%zu) '%s'\n",
relo_sec_name, sec_idx, sec_name);
nrels = shdr->sh_size / shdr->sh_entsize;
for (i = 0; i < nrels; i++) {
rel = elf_rel_by_idx(data, i);
if (!rel) {
pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i);
return -LIBBPF_ERRNO__FORMAT;
}
sym_idx = ELF64_R_SYM(rel->r_info);
sym = elf_sym_by_idx(obj, sym_idx);
if (!sym) {
pr_warn("sec '%s': symbol #%zu not found for relo #%d\n",
relo_sec_name, sym_idx, i);
return -LIBBPF_ERRNO__FORMAT;
}
if (sym->st_shndx >= obj->efile.sec_cnt) {
pr_warn("sec '%s': corrupted symbol #%zu pointing to invalid section #%zu for relo #%d\n",
relo_sec_name, sym_idx, (size_t)sym->st_shndx, i);
return -LIBBPF_ERRNO__FORMAT;
}
if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) {
pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n",
relo_sec_name, (size_t)rel->r_offset, i);
return -LIBBPF_ERRNO__FORMAT;
}
insn_idx = rel->r_offset / BPF_INSN_SZ;
/* relocations against static functions are recorded as
* relocations against the section that contains a function;
* in such case, symbol will be STT_SECTION and sym.st_name
* will point to empty string (0), so fetch section name
* instead
*/
if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION && sym->st_name == 0)
sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym->st_shndx));
else
sym_name = elf_sym_str(obj, sym->st_name);
sym_name = sym_name ?: "<?";
pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n",
relo_sec_name, i, insn_idx, sym_name);
prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
if (!prog) {
pr_debug("sec '%s': relo #%d: couldn't find program in section '%s' for insn #%u, probably overridden weak function, skipping...\n",
relo_sec_name, i, sec_name, insn_idx);
continue;
}
relos = libbpf_reallocarray(prog->reloc_desc,
prog->nr_reloc + 1, sizeof(*relos));
if (!relos)
return -ENOMEM;
prog->reloc_desc = relos;
/* adjust insn_idx to local BPF program frame of reference */
insn_idx -= prog->sec_insn_off;
err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc],
insn_idx, sym_name, sym, rel);
if (err)
return err;
prog->nr_reloc++;
}
return 0;
}
static int map_fill_btf_type_info(struct bpf_object *obj, struct bpf_map *map)
{
int id;
if (!obj->btf)
return -ENOENT;
/* if it's BTF-defined map, we don't need to search for type IDs.
* For struct_ops map, it does not need btf_key_type_id and
* btf_value_type_id.
*/
if (map->sec_idx == obj->efile.btf_maps_shndx || bpf_map__is_struct_ops(map))
return 0;
/*
* LLVM annotates global data differently in BTF, that is,
* only as '.data', '.bss' or '.rodata'.
*/
if (!bpf_map__is_internal(map))
return -ENOENT;
id = btf__find_by_name(obj->btf, map->real_name);
if (id < 0)
return id;
map->btf_key_type_id = 0;
map->btf_value_type_id = id;
return 0;
}
static int bpf_get_map_info_from_fdinfo(int fd, struct bpf_map_info *info)
{
char file[PATH_MAX], buff[4096];
FILE *fp;
__u32 val;
int err;
snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
memset(info, 0, sizeof(*info));
fp = fopen(file, "r");
if (!fp) {
err = -errno;
pr_warn("failed to open %s: %d. No procfs support?\n", file,
err);
return err;
}
while (fgets(buff, sizeof(buff), fp)) {
if (sscanf(buff, "map_type:\t%u", &val) == 1)
info->type = val;
else if (sscanf(buff, "key_size:\t%u", &val) == 1)
info->key_size = val;
else if (sscanf(buff, "value_size:\t%u", &val) == 1)
info->value_size = val;
else if (sscanf(buff, "max_entries:\t%u", &val) == 1)
info->max_entries = val;
else if (sscanf(buff, "map_flags:\t%i", &val) == 1)
info->map_flags = val;
}
fclose(fp);
return 0;
}
bool bpf_map__autocreate(const struct bpf_map *map)
{
return map->autocreate;
}
int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate)
{
if (map->obj->loaded)
return libbpf_err(-EBUSY);
map->autocreate = autocreate;
return 0;
}
int bpf_map__reuse_fd(struct bpf_map *map, int fd)
{
struct bpf_map_info info;
__u32 len = sizeof(info), name_len;
int new_fd, err;
char *new_name;
memset(&info, 0, len);
err = bpf_map_get_info_by_fd(fd, &info, &len);
if (err && errno == EINVAL)
err = bpf_get_map_info_from_fdinfo(fd, &info);
if (err)
return libbpf_err(err);
name_len = strlen(info.name);
if (name_len == BPF_OBJ_NAME_LEN - 1 && strncmp(map->name, info.name, name_len) == 0)
new_name = strdup(map->name);
else
new_name = strdup(info.name);
if (!new_name)
return libbpf_err(-errno);
new_fd = open("/", O_RDONLY | O_CLOEXEC);
if (new_fd < 0) {
err = -errno;
goto err_free_new_name;
}
new_fd = dup3(fd, new_fd, O_CLOEXEC);
if (new_fd < 0) {
err = -errno;
goto err_close_new_fd;
}
err = zclose(map->fd);
if (err) {
err = -errno;
goto err_close_new_fd;
}
free(map->name);
map->fd = new_fd;
map->name = new_name;
map->def.type = info.type;
map->def.key_size = info.key_size;
map->def.value_size = info.value_size;
map->def.max_entries = info.max_entries;
map->def.map_flags = info.map_flags;
map->btf_key_type_id = info.btf_key_type_id;
map->btf_value_type_id = info.btf_value_type_id;
map->reused = true;
map->map_extra = info.map_extra;
return 0;
err_close_new_fd:
close(new_fd);
err_free_new_name:
free(new_name);
return libbpf_err(err);
}
__u32 bpf_map__max_entries(const struct bpf_map *map)
{
return map->def.max_entries;
}
struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
{
if (!bpf_map_type__is_map_in_map(map->def.type))
return errno = EINVAL, NULL;
return map->inner_map;
}
int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
{
if (map->obj->loaded)
return libbpf_err(-EBUSY);
map->def.max_entries = max_entries;
/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
if (map_is_ringbuf(map))
map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
return 0;
}
static int
bpf_object__probe_loading(struct bpf_object *obj)
{
char *cp, errmsg[STRERR_BUFSIZE];
struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
int ret, insn_cnt = ARRAY_SIZE(insns);
if (obj->gen_loader)
return 0;
ret = bump_rlimit_memlock();
if (ret)
pr_warn("Failed to bump RLIMIT_MEMLOCK (err = %d), you might need to do it explicitly!\n", ret);
/* make sure basic loading works */
ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
if (ret < 0)
ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL);
if (ret < 0) {
ret = errno;
cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
pr_warn("Error in %s():%s(%d). Couldn't load trivial BPF "
"program. Make sure your kernel supports BPF "
"(CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is "
"set to big enough value.\n", __func__, cp, ret);
return -ret;
}
close(ret);
return 0;
}
static int probe_fd(int fd)
{
if (fd >= 0)
close(fd);
return fd >= 0;
}
static int probe_kern_prog_name(void)
{
const size_t attr_sz = offsetofend(union bpf_attr, prog_name);
struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
union bpf_attr attr;
int ret;
memset(&attr, 0, attr_sz);
attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
attr.license = ptr_to_u64("GPL");
attr.insns = ptr_to_u64(insns);
attr.insn_cnt = (__u32)ARRAY_SIZE(insns);
libbpf_strlcpy(attr.prog_name, "libbpf_nametest", sizeof(attr.prog_name));
/* make sure loading with name works */
ret = sys_bpf_prog_load(&attr, attr_sz, PROG_LOAD_ATTEMPTS);
return probe_fd(ret);
}
static int probe_kern_global_data(void)
{
char *cp, errmsg[STRERR_BUFSIZE];
struct bpf_insn insns[] = {
BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16),
BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
int ret, map, insn_cnt = ARRAY_SIZE(insns);
map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_global", sizeof(int), 32, 1, NULL);
if (map < 0) {
ret = -errno;
cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
__func__, cp, -ret);
return ret;
}
insns[0].imm = map;
ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
close(map);
return probe_fd(ret);
}
static int probe_kern_btf(void)
{
static const char strs[] = "\0int";
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_btf_func(void)
{
static const char strs[] = "\0int\0x\0a";
/* void x(int a) {} */
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* FUNC_PROTO */ /* [2] */
BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
BTF_PARAM_ENC(7, 1),
/* FUNC x */ /* [3] */
BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_btf_func_global(void)
{
static const char strs[] = "\0int\0x\0a";
/* static void x(int a) {} */
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* FUNC_PROTO */ /* [2] */
BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
BTF_PARAM_ENC(7, 1),
/* FUNC x BTF_FUNC_GLOBAL */ /* [3] */
BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_btf_datasec(void)
{
static const char strs[] = "\0x\0.data";
/* static int a; */
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* VAR x */ /* [2] */
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
BTF_VAR_STATIC,
/* DATASEC val */ /* [3] */
BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
BTF_VAR_SECINFO_ENC(2, 0, 4),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_btf_float(void)
{
static const char strs[] = "\0float";
__u32 types[] = {
/* float */
BTF_TYPE_FLOAT_ENC(1, 4),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_btf_decl_tag(void)
{
static const char strs[] = "\0tag";
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* VAR x */ /* [2] */
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
BTF_VAR_STATIC,
/* attr */
BTF_TYPE_DECL_TAG_ENC(1, 2, -1),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_btf_type_tag(void)
{
static const char strs[] = "\0tag";
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* attr */
BTF_TYPE_TYPE_TAG_ENC(1, 1), /* [2] */
/* ptr */
BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2), /* [3] */
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_array_mmap(void)
{
LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_MMAPABLE);
int fd;
fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_mmap", sizeof(int), sizeof(int), 1, &opts);
return probe_fd(fd);
}
static int probe_kern_exp_attach_type(void)
{
LIBBPF_OPTS(bpf_prog_load_opts, opts, .expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE);
struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
int fd, insn_cnt = ARRAY_SIZE(insns);
/* use any valid combination of program type and (optional)
* non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS)
* to see if kernel supports expected_attach_type field for
* BPF_PROG_LOAD command
*/
fd = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, NULL, "GPL", insns, insn_cnt, &opts);
return probe_fd(fd);
}
static int probe_kern_probe_read_kernel(void)
{
struct bpf_insn insns[] = {
BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), /* r1 = r10 (fp) */
BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8), /* r1 += -8 */
BPF_MOV64_IMM(BPF_REG_2, 8), /* r2 = 8 */
BPF_MOV64_IMM(BPF_REG_3, 0), /* r3 = 0 */
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel),
BPF_EXIT_INSN(),
};
int fd, insn_cnt = ARRAY_SIZE(insns);
fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL);
return probe_fd(fd);
}
static int probe_prog_bind_map(void)
{
char *cp, errmsg[STRERR_BUFSIZE];
struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
int ret, map, prog, insn_cnt = ARRAY_SIZE(insns);
map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_det_bind", sizeof(int), 32, 1, NULL);
if (map < 0) {
ret = -errno;
cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
__func__, cp, -ret);
return ret;
}
prog = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
if (prog < 0) {
close(map);
return 0;
}
ret = bpf_prog_bind_map(prog, map, NULL);
close(map);
close(prog);
return ret >= 0;
}
static int probe_module_btf(void)
{
static const char strs[] = "\0int";
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
};
struct bpf_btf_info info;
__u32 len = sizeof(info);
char name[16];
int fd, err;
fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs));
if (fd < 0)
return 0; /* BTF not supported at all */
memset(&info, 0, sizeof(info));
info.name = ptr_to_u64(name);
info.name_len = sizeof(name);
/* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer;
* kernel's module BTF support coincides with support for
* name/name_len fields in struct bpf_btf_info.
*/
err = bpf_btf_get_info_by_fd(fd, &info, &len);
close(fd);
return !err;
}
static int probe_perf_link(void)
{
struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
int prog_fd, link_fd, err;
prog_fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL",
insns, ARRAY_SIZE(insns), NULL);
if (prog_fd < 0)
return -errno;
/* use invalid perf_event FD to get EBADF, if link is supported;
* otherwise EINVAL should be returned
*/
link_fd = bpf_link_create(prog_fd, -1, BPF_PERF_EVENT, NULL);
err = -errno; /* close() can clobber errno */
if (link_fd >= 0)
close(link_fd);
close(prog_fd);
return link_fd < 0 && err == -EBADF;
}
static int probe_kern_bpf_cookie(void)
{
struct bpf_insn insns[] = {
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_attach_cookie),
BPF_EXIT_INSN(),
};
int ret, insn_cnt = ARRAY_SIZE(insns);
ret = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", insns, insn_cnt, NULL);
return probe_fd(ret);
}
static int probe_kern_btf_enum64(void)
{
static const char strs[] = "\0enum64";
__u32 types[] = {
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_ENUM64, 0, 0), 8),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_syscall_wrapper(void);
enum kern_feature_result {
FEAT_UNKNOWN = 0,
FEAT_SUPPORTED = 1,
FEAT_MISSING = 2,
};
typedef int (*feature_probe_fn)(void);
static struct kern_feature_desc {
const char *desc;
feature_probe_fn probe;
enum kern_feature_result res;
} feature_probes[__FEAT_CNT] = {
[FEAT_PROG_NAME] = {
"BPF program name", probe_kern_prog_name,
},
[FEAT_GLOBAL_DATA] = {
"global variables", probe_kern_global_data,
},
[FEAT_BTF] = {
"minimal BTF", probe_kern_btf,
},
[FEAT_BTF_FUNC] = {
"BTF functions", probe_kern_btf_func,
},
[FEAT_BTF_GLOBAL_FUNC] = {
"BTF global function", probe_kern_btf_func_global,
},
[FEAT_BTF_DATASEC] = {
"BTF data section and variable", probe_kern_btf_datasec,
},
[FEAT_ARRAY_MMAP] = {
"ARRAY map mmap()", probe_kern_array_mmap,
},
[FEAT_EXP_ATTACH_TYPE] = {
"BPF_PROG_LOAD expected_attach_type attribute",
probe_kern_exp_attach_type,
},
[FEAT_PROBE_READ_KERN] = {
"bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel,
},
[FEAT_PROG_BIND_MAP] = {
"BPF_PROG_BIND_MAP support", probe_prog_bind_map,
},
[FEAT_MODULE_BTF] = {
"module BTF support", probe_module_btf,
},
[FEAT_BTF_FLOAT] = {
"BTF_KIND_FLOAT support", probe_kern_btf_float,
},
[FEAT_PERF_LINK] = {
"BPF perf link support", probe_perf_link,
},
[FEAT_BTF_DECL_TAG] = {
"BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
},
[FEAT_BTF_TYPE_TAG] = {
"BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag,
},
[FEAT_MEMCG_ACCOUNT] = {
"memcg-based memory accounting", probe_memcg_account,
},
[FEAT_BPF_COOKIE] = {
"BPF cookie support", probe_kern_bpf_cookie,
},
[FEAT_BTF_ENUM64] = {
"BTF_KIND_ENUM64 support", probe_kern_btf_enum64,
},
[FEAT_SYSCALL_WRAPPER] = {
"Kernel using syscall wrapper", probe_kern_syscall_wrapper,
},
};
bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
{
struct kern_feature_desc *feat = &feature_probes[feat_id];
int ret;
if (obj && obj->gen_loader)
/* To generate loader program assume the latest kernel
* to avoid doing extra prog_load, map_create syscalls.
*/
return true;
if (READ_ONCE(feat->res) == FEAT_UNKNOWN) {
ret = feat->probe();
if (ret > 0) {
WRITE_ONCE(feat->res, FEAT_SUPPORTED);
} else if (ret == 0) {
WRITE_ONCE(feat->res, FEAT_MISSING);
} else {
pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret);
WRITE_ONCE(feat->res, FEAT_MISSING);
}
}
return READ_ONCE(feat->res) == FEAT_SUPPORTED;
}
static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
{
struct bpf_map_info map_info;
char msg[STRERR_BUFSIZE];
__u32 map_info_len = sizeof(map_info);
int err;
memset(&map_info, 0, map_info_len);
err = bpf_map_get_info_by_fd(map_fd, &map_info, &map_info_len);
if (err && errno == EINVAL)
err = bpf_get_map_info_from_fdinfo(map_fd, &map_info);
if (err) {
pr_warn("failed to get map info for map FD %d: %s\n", map_fd,
libbpf_strerror_r(errno, msg, sizeof(msg)));
return false;
}
return (map_info.type == map->def.type &&
map_info.key_size == map->def.key_size &&
map_info.value_size == map->def.value_size &&
map_info.max_entries == map->def.max_entries &&
map_info.map_flags == map->def.map_flags &&
map_info.map_extra == map->map_extra);
}
static int
bpf_object__reuse_map(struct bpf_map *map)
{
char *cp, errmsg[STRERR_BUFSIZE];
int err, pin_fd;
pin_fd = bpf_obj_get(map->pin_path);
if (pin_fd < 0) {
err = -errno;
if (err == -ENOENT) {
pr_debug("found no pinned map to reuse at '%s'\n",
map->pin_path);
return 0;
}
cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
pr_warn("couldn't retrieve pinned map '%s': %s\n",
map->pin_path, cp);
return err;
}
if (!map_is_reuse_compat(map, pin_fd)) {
pr_warn("couldn't reuse pinned map at '%s': parameter mismatch\n",
map->pin_path);
close(pin_fd);
return -EINVAL;
}
err = bpf_map__reuse_fd(map, pin_fd);
close(pin_fd);
if (err)
return err;
map->pinned = true;
pr_debug("reused pinned map at '%s'\n", map->pin_path);
return 0;
}
static int
bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
{
enum libbpf_map_type map_type = map->libbpf_type;
char *cp, errmsg[STRERR_BUFSIZE];
int err, zero = 0;
if (obj->gen_loader) {
bpf_gen__map_update_elem(obj->gen_loader, map - obj->maps,
map->mmaped, map->def.value_size);
if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG)
bpf_gen__map_freeze(obj->gen_loader, map - obj->maps);
return 0;
}
err = bpf_map_update_elem(map->fd, &zero, map->mmaped, 0);
if (err) {
err = -errno;
cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
pr_warn("Error setting initial map(%s) contents: %s\n",
map->name, cp);
return err;
}
/* Freeze .rodata and .kconfig map as read-only from syscall side. */
if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG) {
err = bpf_map_freeze(map->fd);
if (err) {
err = -errno;
cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
pr_warn("Error freezing map(%s) as read-only: %s\n",
map->name, cp);
return err;
}
}
return 0;
}
static void bpf_map__destroy(struct bpf_map *map);
static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, bool is_inner)
{
LIBBPF_OPTS(bpf_map_create_opts, create_attr);
struct bpf_map_def *def = &map->def;
const char *map_name = NULL;
int err = 0;
if (kernel_supports(obj, FEAT_PROG_NAME))
map_name = map->name;
create_attr.map_ifindex = map->map_ifindex;
create_attr.map_flags = def->map_flags;
create_attr.numa_node = map->numa_node;
create_attr.map_extra = map->map_extra;
if (bpf_map__is_struct_ops(map))
create_attr.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id;
if (obj->btf && btf__fd(obj->btf) >= 0) {
create_attr.btf_fd = btf__fd(obj->btf);
create_attr.btf_key_type_id = map->btf_key_type_id;
create_attr.btf_value_type_id = map->btf_value_type_id;
}
if (bpf_map_type__is_map_in_map(def->type)) {
if (map->inner_map) {
err = bpf_object__create_map(obj, map->inner_map, true);
if (err) {
pr_warn("map '%s': failed to create inner map: %d\n",
map->name, err);
return err;
}
map->inner_map_fd = bpf_map__fd(map->inner_map);
}
if (map->inner_map_fd >= 0)
create_attr.inner_map_fd = map->inner_map_fd;
}
switch (def->type) {
case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
case BPF_MAP_TYPE_CGROUP_ARRAY:
case BPF_MAP_TYPE_STACK_TRACE:
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
case BPF_MAP_TYPE_DEVMAP:
case BPF_MAP_TYPE_DEVMAP_HASH:
case BPF_MAP_TYPE_CPUMAP:
case BPF_MAP_TYPE_XSKMAP:
case BPF_MAP_TYPE_SOCKMAP:
case BPF_MAP_TYPE_SOCKHASH:
case BPF_MAP_TYPE_QUEUE:
case BPF_MAP_TYPE_STACK:
create_attr.btf_fd = 0;
create_attr.btf_key_type_id = 0;
create_attr.btf_value_type_id = 0;
map->btf_key_type_id = 0;
map->btf_value_type_id = 0;
default:
break;
}
if (obj->gen_loader) {
bpf_gen__map_create(obj->gen_loader, def->type, map_name,
def->key_size, def->value_size, def->max_entries,
&create_attr, is_inner ? -1 : map - obj->maps);
/* Pretend to have valid FD to pass various fd >= 0 checks.
* This fd == 0 will not be used with any syscall and will be reset to -1 eventually.
*/
map->fd = 0;
} else {
map->fd = bpf_map_create(def->type, map_name,
def->key_size, def->value_size,
def->max_entries, &create_attr);
}
if (map->fd < 0 && (create_attr.btf_key_type_id ||
create_attr.btf_value_type_id)) {
char *cp, errmsg[STRERR_BUFSIZE];
err = -errno;
cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
map->name, cp, err);
create_attr.btf_fd = 0;
create_attr.btf_key_type_id = 0;
create_attr.btf_value_type_id = 0;
map->btf_key_type_id = 0;
map->btf_value_type_id = 0;
map->fd = bpf_map_create(def->type, map_name,
def->key_size, def->value_size,
def->max_entries, &create_attr);
}
err = map->fd < 0 ? -errno : 0;
if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) {
if (obj->gen_loader)
map->inner_map->fd = -1;
bpf_map__destroy(map->inner_map);
zfree(&map->inner_map);
}
return err;
}
static int init_map_in_map_slots(struct bpf_object *obj, struct bpf_map *map)
{
const struct bpf_map *targ_map;
unsigned int i;
int fd, err = 0;
for (i = 0; i < map->init_slots_sz; i++) {
if (!map->init_slots[i])
continue;
targ_map = map->init_slots[i];
fd = bpf_map__fd(targ_map);
if (obj->gen_loader) {
bpf_gen__populate_outer_map(obj->gen_loader,
map - obj->maps, i,
targ_map - obj->maps);
} else {
err = bpf_map_update_elem(map->fd, &i, &fd, 0);
}
if (err) {
err = -errno;
pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
map->name, i, targ_map->name, fd, err);
return err;
}
pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
map->name, i, targ_map->name, fd);
}
zfree(&map->init_slots);
map->init_slots_sz = 0;
return 0;
}
static int init_prog_array_slots(struct bpf_object *obj, struct bpf_map *map)
{
const struct bpf_program *targ_prog;
unsigned int i;
int fd, err;
if (obj->gen_loader)
return -ENOTSUP;
for (i = 0; i < map->init_slots_sz; i++) {
if (!map->init_slots[i])
continue;
targ_prog = map->init_slots[i];
fd = bpf_program__fd(targ_prog);
err = bpf_map_update_elem(map->fd, &i, &fd, 0);
if (err) {
err = -errno;
pr_warn("map '%s': failed to initialize slot [%d] to prog '%s' fd=%d: %d\n",
map->name, i, targ_prog->name, fd, err);
return err;
}
pr_debug("map '%s': slot [%d] set to prog '%s' fd=%d\n",
map->name, i, targ_prog->name, fd);
}
zfree(&map->init_slots);
map->init_slots_sz = 0;
return 0;
}
static int bpf_object_init_prog_arrays(struct bpf_object *obj)
{
struct bpf_map *map;
int i, err;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
if (!map->init_slots_sz || map->def.type != BPF_MAP_TYPE_PROG_ARRAY)
continue;
err = init_prog_array_slots(obj, map);
if (err < 0) {
zclose(map->fd);
return err;
}
}
return 0;
}
static int map_set_def_max_entries(struct bpf_map *map)
{
if (map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !map->def.max_entries) {
int nr_cpus;
nr_cpus = libbpf_num_possible_cpus();
if (nr_cpus < 0) {
pr_warn("map '%s': failed to determine number of system CPUs: %d\n",
map->name, nr_cpus);
return nr_cpus;
}
pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus);
map->def.max_entries = nr_cpus;
}
return 0;
}
static int
bpf_object__create_maps(struct bpf_object *obj)
{
struct bpf_map *map;
char *cp, errmsg[STRERR_BUFSIZE];
unsigned int i, j;
int err;
bool retried;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
/* To support old kernels, we skip creating global data maps
* (.rodata, .data, .kconfig, etc); later on, during program
* loading, if we detect that at least one of the to-be-loaded
* programs is referencing any global data map, we'll error
* out with program name and relocation index logged.
* This approach allows to accommodate Clang emitting
* unnecessary .rodata.str1.1 sections for string literals,
* but also it allows to have CO-RE applications that use
* global variables in some of BPF programs, but not others.
* If those global variable-using programs are not loaded at
* runtime due to bpf_program__set_autoload(prog, false),
* bpf_object loading will succeed just fine even on old
* kernels.
*/
if (bpf_map__is_internal(map) && !kernel_supports(obj, FEAT_GLOBAL_DATA))
map->autocreate = false;
if (!map->autocreate) {
pr_debug("map '%s': skipped auto-creating...\n", map->name);
continue;
}
err = map_set_def_max_entries(map);
if (err)
goto err_out;
retried = false;
retry:
if (map->pin_path) {
err = bpf_object__reuse_map(map);
if (err) {
pr_warn("map '%s': error reusing pinned map\n",
map->name);
goto err_out;
}
if (retried && map->fd < 0) {
pr_warn("map '%s': cannot find pinned map\n",
map->name);
err = -ENOENT;
goto err_out;
}
}
if (map->fd >= 0) {
pr_debug("map '%s': skipping creation (preset fd=%d)\n",
map->name, map->fd);
} else {
err = bpf_object__create_map(obj, map, false);
if (err)
goto err_out;
pr_debug("map '%s': created successfully, fd=%d\n",
map->name, map->fd);
if (bpf_map__is_internal(map)) {
err = bpf_object__populate_internal_map(obj, map);
if (err < 0) {
zclose(map->fd);
goto err_out;
}
}
if (map->init_slots_sz && map->def.type != BPF_MAP_TYPE_PROG_ARRAY) {
err = init_map_in_map_slots(obj, map);
if (err < 0) {
zclose(map->fd);
goto err_out;
}
}
}
if (map->pin_path && !map->pinned) {
err = bpf_map__pin(map, NULL);
if (err) {
zclose(map->fd);
if (!retried && err == -EEXIST) {
retried = true;
goto retry;
}
pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
map->name, map->pin_path, err);
goto err_out;
}
}
}
return 0;
err_out:
cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
pr_warn("map '%s': failed to create: %s(%d)\n", map->name, cp, err);
pr_perm_msg(err);
for (j = 0; j < i; j++)
zclose(obj->maps[j].fd);
return err;
}
static bool bpf_core_is_flavor_sep(const char *s)
{
/* check X___Y name pattern, where X and Y are not underscores */
return s[0] != '_' && /* X */
s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */
s[4] != '_'; /* Y */
}
/* Given 'some_struct_name___with_flavor' return the length of a name prefix
* before last triple underscore. Struct name part after last triple
* underscore is ignored by BPF CO-RE relocation during relocation matching.
*/
size_t bpf_core_essential_name_len(const char *name)
{
size_t n = strlen(name);
int i;
for (i = n - 5; i >= 0; i--) {
if (bpf_core_is_flavor_sep(name + i))
return i + 1;
}
return n;
}
void bpf_core_free_cands(struct bpf_core_cand_list *cands)
{
if (!cands)
return;
free(cands->cands);
free(cands);
}
int bpf_core_add_cands(struct bpf_core_cand *local_cand,
size_t local_essent_len,
const struct btf *targ_btf,
const char *targ_btf_name,
int targ_start_id,
struct bpf_core_cand_list *cands)
{
struct bpf_core_cand *new_cands, *cand;
const struct btf_type *t, *local_t;
const char *targ_name, *local_name;
size_t targ_essent_len;
int n, i;
local_t = btf__type_by_id(local_cand->btf, local_cand->id);
local_name = btf__str_by_offset(local_cand->btf, local_t->name_off);
n = btf__type_cnt(targ_btf);
for (i = targ_start_id; i < n; i++) {
t = btf__type_by_id(targ_btf, i);
if (!btf_kind_core_compat(t, local_t))
continue;
targ_name = btf__name_by_offset(targ_btf, t->name_off);
if (str_is_empty(targ_name))
continue;
targ_essent_len = bpf_core_essential_name_len(targ_name);
if (targ_essent_len != local_essent_len)
continue;
if (strncmp(local_name, targ_name, local_essent_len) != 0)
continue;
pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n",
local_cand->id, btf_kind_str(local_t),
local_name, i, btf_kind_str(t), targ_name,
targ_btf_name);
new_cands = libbpf_reallocarray(cands->cands, cands->len + 1,
sizeof(*cands->cands));
if (!new_cands)
return -ENOMEM;
cand = &new_cands[cands->len];
cand->btf = targ_btf;
cand->id = i;
cands->cands = new_cands;
cands->len++;
}
return 0;
}
static int load_module_btfs(struct bpf_object *obj)
{
struct bpf_btf_info info;
struct module_btf *mod_btf;
struct btf *btf;
char name[64];
__u32 id = 0, len;
int err, fd;
if (obj->btf_modules_loaded)
return 0;
if (obj->gen_loader)
return 0;
/* don't do this again, even if we find no module BTFs */
obj->btf_modules_loaded = true;
/* kernel too old to support module BTFs */
if (!kernel_supports(obj, FEAT_MODULE_BTF))
return 0;
while (true) {
err = bpf_btf_get_next_id(id, &id);
if (err && errno == ENOENT)
return 0;
if (err) {
err = -errno;
pr_warn("failed to iterate BTF objects: %d\n", err);
return err;
}
fd = bpf_btf_get_fd_by_id(id);
if (fd < 0) {
if (errno == ENOENT)
continue; /* expected race: BTF was unloaded */
err = -errno;
pr_warn("failed to get BTF object #%d FD: %d\n", id, err);
return err;
}
len = sizeof(info);
memset(&info, 0, sizeof(info));
info.name = ptr_to_u64(name);
info.name_len = sizeof(name);
err = bpf_btf_get_info_by_fd(fd, &info, &len);
if (err) {
err = -errno;
pr_warn("failed to get BTF object #%d info: %d\n", id, err);
goto err_out;
}
/* ignore non-module BTFs */
if (!info.kernel_btf || strcmp(name, "vmlinux") == 0) {
close(fd);
continue;
}
btf = btf_get_from_fd(fd, obj->btf_vmlinux);
err = libbpf_get_error(btf);
if (err) {
pr_warn("failed to load module [%s]'s BTF object #%d: %d\n",
name, id, err);
goto err_out;
}
err = libbpf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);
if (err)
goto err_out;
mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
mod_btf->btf = btf;
mod_btf->id = id;
mod_btf->fd = fd;
mod_btf->name = strdup(name);
if (!mod_btf->name) {
err = -ENOMEM;
goto err_out;
}
continue;
err_out:
close(fd);
return err;
}
return 0;
}
static struct bpf_core_cand_list *
bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)
{
struct bpf_core_cand local_cand = {};
struct bpf_core_cand_list *cands;
const struct btf *main_btf;
const struct btf_type *local_t;
const char *local_name;
size_t local_essent_len;
int err, i;
local_cand.btf = local_btf;
local_cand.id = local_type_id;
local_t = btf__type_by_id(local_btf, local_type_id);
if (!local_t)
return ERR_PTR(-EINVAL);
local_name = btf__name_by_offset(local_btf, local_t->name_off);
if (str_is_empty(local_name))
return ERR_PTR(-EINVAL);
local_essent_len = bpf_core_essential_name_len(local_name);
cands = calloc(1, sizeof(*cands));
if (!cands)
return ERR_PTR(-ENOMEM);
/* Attempt to find target candidates in vmlinux BTF first */
main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux;
err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands);
if (err)
goto err_out;
/* if vmlinux BTF has any candidate, don't got for module BTFs */
if (cands->len)
return cands;
/* if vmlinux BTF was overridden, don't attempt to load module BTFs */
if (obj->btf_vmlinux_override)
return cands;
/* now look through module BTFs, trying to still find candidates */
err = load_module_btfs(obj);
if (err)
goto err_out;
for (i = 0; i < obj->btf_module_cnt; i++) {
err = bpf_core_add_cands(&local_cand, local_essent_len,
obj->btf_modules[i].btf,
obj->btf_modules[i].name,
btf__type_cnt(obj->btf_vmlinux),
cands);
if (err)
goto err_out;
}
return cands;
err_out:
bpf_core_free_cands(cands);
return ERR_PTR(err);
}
/* Check local and target types for compatibility. This check is used for
* type-based CO-RE relocations and follow slightly different rules than
* field-based relocations. This function assumes that root types were already
* checked for name match. Beyond that initial root-level name check, names
* are completely ignored. Compatibility rules are as follows:
* - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but
* kind should match for local and target types (i.e., STRUCT is not
* compatible with UNION);
* - for ENUMs, the size is ignored;
* - for INT, size and signedness are ignored;
* - for ARRAY, dimensionality is ignored, element types are checked for
* compatibility recursively;
* - CONST/VOLATILE/RESTRICT modifiers are ignored;
* - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
* - FUNC_PROTOs are compatible if they have compatible signature: same
* number of input args and compatible return and argument types.
* These rules are not set in stone and probably will be adjusted as we get
* more experience with using BPF CO-RE relocations.
*/
int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id)
{
return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id, 32);
}
int bpf_core_types_match(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id)
{
return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, 32);
}
static size_t bpf_core_hash_fn(const long key, void *ctx)
{
return key;
}
static bool bpf_core_equal_fn(const long k1, const long k2, void *ctx)
{
return k1 == k2;
}
static int record_relo_core(struct bpf_program *prog,
const struct bpf_core_relo *core_relo, int insn_idx)
{
struct reloc_desc *relos, *relo;
relos = libbpf_reallocarray(prog->reloc_desc,
prog->nr_reloc + 1, sizeof(*relos));
if (!relos)
return -ENOMEM;
relo = &relos[prog->nr_reloc];
relo->type = RELO_CORE;
relo->insn_idx = insn_idx;
relo->core_relo = core_relo;
prog->reloc_desc = relos;
prog->nr_reloc++;
return 0;
}
static const struct bpf_core_relo *find_relo_core(struct bpf_program *prog, int insn_idx)
{
struct reloc_desc *relo;
int i;
for (i = 0; i < prog->nr_reloc; i++) {
relo = &prog->reloc_desc[i];
if (relo->type != RELO_CORE || relo->insn_idx != insn_idx)
continue;
return relo->core_relo;
}
return NULL;
}
static int bpf_core_resolve_relo(struct bpf_program *prog,
const struct bpf_core_relo *relo,
int relo_idx,
const struct btf *local_btf,
struct hashmap *cand_cache,
struct bpf_core_relo_res *targ_res)
{
struct bpf_core_spec specs_scratch[3] = {};
struct bpf_core_cand_list *cands = NULL;
const char *prog_name = prog->name;
const struct btf_type *local_type;
const char *local_name;
__u32 local_id = relo->type_id;
int err;
local_type = btf__type_by_id(local_btf, local_id);
if (!local_type)
return -EINVAL;
local_name = btf__name_by_offset(local_btf, local_type->name_off);
if (!local_name)
return -EINVAL;
if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
!hashmap__find(cand_cache, local_id, &cands)) {
cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
if (IS_ERR(cands)) {
pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
prog_name, relo_idx, local_id, btf_kind_str(local_type),
local_name, PTR_ERR(cands));
return PTR_ERR(cands);
}
err = hashmap__set(cand_cache, local_id, cands, NULL, NULL);
if (err) {
bpf_core_free_cands(cands);
return err;
}
}
return bpf_core_calc_relo_insn(prog_name, relo, relo_idx, local_btf, cands, specs_scratch,
targ_res);
}
static int
bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
{
const struct btf_ext_info_sec *sec;
struct bpf_core_relo_res targ_res;
const struct bpf_core_relo *rec;
const struct btf_ext_info *seg;
struct hashmap_entry *entry;
struct hashmap *cand_cache = NULL;
struct bpf_program *prog;
struct bpf_insn *insn;
const char *sec_name;
int i, err = 0, insn_idx, sec_idx, sec_num;
if (obj->btf_ext->core_relo_info.len == 0)
return 0;
if (targ_btf_path) {
obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL);
err = libbpf_get_error(obj->btf_vmlinux_override);
if (err) {
pr_warn("failed to parse target BTF: %d\n", err);
return err;
}
}
cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
if (IS_ERR(cand_cache)) {
err = PTR_ERR(cand_cache);
goto out;
}
seg = &obj->btf_ext->core_relo_info;
sec_num = 0;
for_each_btf_ext_sec(seg, sec) {
sec_idx = seg->sec_idxs[sec_num];
sec_num++;
sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
if (str_is_empty(sec_name)) {
err = -EINVAL;
goto out;
}
pr_debug("sec '%s': found %d CO-RE relocations\n", sec_name, sec->num_info);
for_each_btf_ext_rec(seg, sec, i, rec) {
if (rec->insn_off % BPF_INSN_SZ)
return -EINVAL;
insn_idx = rec->insn_off / BPF_INSN_SZ;
prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
if (!prog) {
/* When __weak subprog is "overridden" by another instance
* of the subprog from a different object file, linker still
* appends all the .BTF.ext info that used to belong to that
* eliminated subprogram.
* This is similar to what x86-64 linker does for relocations.
* So just ignore such relocations just like we ignore
* subprog instructions when discovering subprograms.
*/
pr_debug("sec '%s': skipping CO-RE relocation #%d for insn #%d belonging to eliminated weak subprogram\n",
sec_name, i, insn_idx);
continue;
}
/* no need to apply CO-RE relocation if the program is
* not going to be loaded
*/
if (!prog->autoload)
continue;
/* adjust insn_idx from section frame of reference to the local
* program's frame of reference; (sub-)program code is not yet
* relocated, so it's enough to just subtract in-section offset
*/
insn_idx = insn_idx - prog->sec_insn_off;
if (insn_idx >= prog->insns_cnt)
return -EINVAL;
insn = &prog->insns[insn_idx];
err = record_relo_core(prog, rec, insn_idx);
if (err) {
pr_warn("prog '%s': relo #%d: failed to record relocation: %d\n",
prog->name, i, err);
goto out;
}
if (prog->obj->gen_loader)
continue;
err = bpf_core_resolve_relo(prog, rec, i, obj->btf, cand_cache, &targ_res);
if (err) {
pr_warn("prog '%s': relo #%d: failed to relocate: %d\n",
prog->name, i, err);
goto out;
}
err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res);
if (err) {
pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %d\n",
prog->name, i, insn_idx, err);
goto out;
}
}
}
out:
/* obj->btf_vmlinux and module BTFs are freed after object load */
btf__free(obj->btf_vmlinux_override);
obj->btf_vmlinux_override = NULL;
if (!IS_ERR_OR_NULL(cand_cache)) {
hashmap__for_each_entry(cand_cache, entry, i) {
bpf_core_free_cands(entry->pvalue);
}
hashmap__free(cand_cache);
}
return err;
}
/* base map load ldimm64 special constant, used also for log fixup logic */
#define MAP_LDIMM64_POISON_BASE 2001000000
#define MAP_LDIMM64_POISON_PFX "200100"
static void poison_map_ldimm64(struct bpf_program *prog, int relo_idx,
int insn_idx, struct bpf_insn *insn,
int map_idx, const struct bpf_map *map)
{
int i;
pr_debug("prog '%s': relo #%d: poisoning insn #%d that loads map #%d '%s'\n",
prog->name, relo_idx, insn_idx, map_idx, map->name);
/* we turn single ldimm64 into two identical invalid calls */
for (i = 0; i < 2; i++) {
insn->code = BPF_JMP | BPF_CALL;
insn->dst_reg = 0;
insn->src_reg = 0;
insn->off = 0;
/* if this instruction is reachable (not a dead code),
* verifier will complain with something like:
* invalid func unknown#2001000123
* where lower 123 is map index into obj->maps[] array
*/
insn->imm = MAP_LDIMM64_POISON_BASE + map_idx;
insn++;
}
}
/* Relocate data references within program code:
* - map references;
* - global variable references;
* - extern references.
*/
static int
bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
{
int i;
for (i = 0; i < prog->nr_reloc; i++) {
struct reloc_desc *relo = &prog->reloc_desc[i];
struct bpf_insn *insn = &prog->insns[relo->insn_idx];
const struct bpf_map *map;
struct extern_desc *ext;
switch (relo->type) {
case RELO_LD64:
map = &obj->maps[relo->map_idx];
if (obj->gen_loader) {
insn[0].src_reg = BPF_PSEUDO_MAP_IDX;
insn[0].imm = relo->map_idx;
} else if (map->autocreate) {
insn[0].src_reg = BPF_PSEUDO_MAP_FD;
insn[0].imm = map->fd;
} else {
poison_map_ldimm64(prog, i, relo->insn_idx, insn,
relo->map_idx, map);
}
break;
case RELO_DATA:
map = &obj->maps[relo->map_idx];
insn[1].imm = insn[0].imm + relo->sym_off;
if (obj->gen_loader) {
insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
insn[0].imm = relo->map_idx;
} else if (map->autocreate) {
insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
insn[0].imm = map->fd;
} else {
poison_map_ldimm64(prog, i, relo->insn_idx, insn,
relo->map_idx, map);
}
break;
case RELO_EXTERN_VAR:
ext = &obj->externs[relo->sym_off];
if (ext->type == EXT_KCFG) {
if (obj->gen_loader) {
insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
insn[0].imm = obj->kconfig_map_idx;
} else {
insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
}
insn[1].imm = ext->kcfg.data_off;
} else /* EXT_KSYM */ {
if (ext->ksym.type_id && ext->is_set) { /* typed ksyms */
insn[0].src_reg = BPF_PSEUDO_BTF_ID;
insn[0].imm = ext->ksym.kernel_btf_id;
insn[1].imm = ext->ksym.kernel_btf_obj_fd;
} else { /* typeless ksyms or unresolved typed ksyms */
insn[0].imm = (__u32)ext->ksym.addr;
insn[1].imm = ext->ksym.addr >> 32;
}
}
break;
case RELO_EXTERN_FUNC:
ext = &obj->externs[relo->sym_off];
insn[0].src_reg = BPF_PSEUDO_KFUNC_CALL;
if (ext->is_set) {
insn[0].imm = ext->ksym.kernel_btf_id;
insn[0].off = ext->ksym.btf_fd_idx;
} else { /* unresolved weak kfunc */
insn[0].imm = 0;
insn[0].off = 0;
}
break;
case RELO_SUBPROG_ADDR:
if (insn[0].src_reg != BPF_PSEUDO_FUNC) {
pr_warn("prog '%s': relo #%d: bad insn\n",
prog->name, i);
return -EINVAL;
}
/* handled already */
break;
case RELO_CALL:
/* handled already */
break;
case RELO_CORE:
/* will be handled by bpf_program_record_relos() */
break;
default:
pr_warn("prog '%s': relo #%d: bad relo type %d\n",
prog->name, i, relo->type);
return -EINVAL;
}
}
return 0;
}
static int adjust_prog_btf_ext_info(const struct bpf_object *obj,
const struct bpf_program *prog,
const struct btf_ext_info *ext_info,
void **prog_info, __u32 *prog_rec_cnt,
__u32 *prog_rec_sz)
{
void *copy_start = NULL, *copy_end = NULL;
void *rec, *rec_end, *new_prog_info;
const struct btf_ext_info_sec *sec;
size_t old_sz, new_sz;
int i, sec_num, sec_idx, off_adj;
sec_num = 0;
for_each_btf_ext_sec(ext_info, sec) {
sec_idx = ext_info->sec_idxs[sec_num];
sec_num++;
if (prog->sec_idx != sec_idx)
continue;
for_each_btf_ext_rec(ext_info, sec, i, rec) {
__u32 insn_off = *(__u32 *)rec / BPF_INSN_SZ;
if (insn_off < prog->sec_insn_off)
continue;
if (insn_off >= prog->sec_insn_off + prog->sec_insn_cnt)
break;
if (!copy_start)
copy_start = rec;
copy_end = rec + ext_info->rec_size;
}
if (!copy_start)
return -ENOENT;
/* append func/line info of a given (sub-)program to the main
* program func/line info
*/
old_sz = (size_t)(*prog_rec_cnt) * ext_info->rec_size;
new_sz = old_sz + (copy_end - copy_start);
new_prog_info = realloc(*prog_info, new_sz);
if (!new_prog_info)
return -ENOMEM;
*prog_info = new_prog_info;
*prog_rec_cnt = new_sz / ext_info->rec_size;
memcpy(new_prog_info + old_sz, copy_start, copy_end - copy_start);
/* Kernel instruction offsets are in units of 8-byte
* instructions, while .BTF.ext instruction offsets generated
* by Clang are in units of bytes. So convert Clang offsets
* into kernel offsets and adjust offset according to program
* relocated position.
*/
off_adj = prog->sub_insn_off - prog->sec_insn_off;
rec = new_prog_info + old_sz;
rec_end = new_prog_info + new_sz;
for (; rec < rec_end; rec += ext_info->rec_size) {
__u32 *insn_off = rec;
*insn_off = *insn_off / BPF_INSN_SZ + off_adj;
}
*prog_rec_sz = ext_info->rec_size;
return 0;
}
return -ENOENT;
}
static int
reloc_prog_func_and_line_info(const struct bpf_object *obj,
struct bpf_program *main_prog,
const struct bpf_program *prog)
{
int err;
/* no .BTF.ext relocation if .BTF.ext is missing or kernel doesn't
* supprot func/line info
*/
if (!obj->btf_ext || !kernel_supports(obj, FEAT_BTF_FUNC))
return 0;
/* only attempt func info relocation if main program's func_info
* relocation was successful
*/
if (main_prog != prog && !main_prog->func_info)
goto line_info;
err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->func_info,
&main_prog->func_info,
&main_prog->func_info_cnt,
&main_prog->func_info_rec_size);
if (err) {
if (err != -ENOENT) {
pr_warn("prog '%s': error relocating .BTF.ext function info: %d\n",
prog->name, err);
return err;
}
if (main_prog->func_info) {
/*
* Some info has already been found but has problem
* in the last btf_ext reloc. Must have to error out.
*/
pr_warn("prog '%s': missing .BTF.ext function info.\n", prog->name);
return err;
}
/* Have problem loading the very first info. Ignore the rest. */
pr_warn("prog '%s': missing .BTF.ext function info for the main program, skipping all of .BTF.ext func info.\n",
prog->name);
}
line_info:
/* don't relocate line info if main program's relocation failed */
if (main_prog != prog && !main_prog->line_info)
return 0;
err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->line_info,
&main_prog->line_info,
&main_prog->line_info_cnt,
&main_prog->line_info_rec_size);
if (err) {
if (err != -ENOENT) {
pr_warn("prog '%s': error relocating .BTF.ext line info: %d\n",
prog->name, err);
return err;
}
if (main_prog->line_info) {
/*
* Some info has already been found but has problem
* in the last btf_ext reloc. Must have to error out.
*/
pr_warn("prog '%s': missing .BTF.ext line info.\n", prog->name);
return err;
}
/* Have problem loading the very first info. Ignore the rest. */
pr_warn("prog '%s': missing .BTF.ext line info for the main program, skipping all of .BTF.ext line info.\n",
prog->name);
}
return 0;
}
static int cmp_relo_by_insn_idx(const void *key, const void *elem)
{
size_t insn_idx = *(const size_t *)key;
const struct reloc_desc *relo = elem;
if (insn_idx == relo->insn_idx)
return 0;
return insn_idx < relo->insn_idx ? -1 : 1;
}
static struct reloc_desc *find_prog_insn_relo(const struct bpf_program *prog, size_t insn_idx)
{
if (!prog->nr_reloc)
return NULL;
return bsearch(&insn_idx, prog->reloc_desc, prog->nr_reloc,
sizeof(*prog->reloc_desc), cmp_relo_by_insn_idx);
}
static int append_subprog_relos(struct bpf_program *main_prog, struct bpf_program *subprog)
{
int new_cnt = main_prog->nr_reloc + subprog->nr_reloc;
struct reloc_desc *relos;
int i;
if (main_prog == subprog)
return 0;
relos = libbpf_reallocarray(main_prog->reloc_desc, new_cnt, sizeof(*relos));
if (!relos)
return -ENOMEM;
if (subprog->nr_reloc)
memcpy(relos + main_prog->nr_reloc, subprog->reloc_desc,
sizeof(*relos) * subprog->nr_reloc);
for (i = main_prog->nr_reloc; i < new_cnt; i++)
relos[i].insn_idx += subprog->sub_insn_off;
/* After insn_idx adjustment the 'relos' array is still sorted
* by insn_idx and doesn't break bsearch.
*/
main_prog->reloc_desc = relos;
main_prog->nr_reloc = new_cnt;
return 0;
}
static int
bpf_object__reloc_code(struct bpf_object *obj, struct bpf_program *main_prog,
struct bpf_program *prog)
{
size_t sub_insn_idx, insn_idx, new_cnt;
struct bpf_program *subprog;
struct bpf_insn *insns, *insn;
struct reloc_desc *relo;
int err;
err = reloc_prog_func_and_line_info(obj, main_prog, prog);
if (err)
return err;
for (insn_idx = 0; insn_idx < prog->sec_insn_cnt; insn_idx++) {
insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
if (!insn_is_subprog_call(insn) && !insn_is_pseudo_func(insn))
continue;
relo = find_prog_insn_relo(prog, insn_idx);
if (relo && relo->type == RELO_EXTERN_FUNC)
/* kfunc relocations will be handled later
* in bpf_object__relocate_data()
*/
continue;
if (relo && relo->type != RELO_CALL && relo->type != RELO_SUBPROG_ADDR) {
pr_warn("prog '%s': unexpected relo for insn #%zu, type %d\n",
prog->name, insn_idx, relo->type);
return -LIBBPF_ERRNO__RELOC;
}
if (relo) {
/* sub-program instruction index is a combination of
* an offset of a symbol pointed to by relocation and
* call instruction's imm field; for global functions,
* call always has imm = -1, but for static functions
* relocation is against STT_SECTION and insn->imm
* points to a start of a static function
*
* for subprog addr relocation, the relo->sym_off + insn->imm is
* the byte offset in the corresponding section.
*/
if (relo->type == RELO_CALL)
sub_insn_idx = relo->sym_off / BPF_INSN_SZ + insn->imm + 1;
else
sub_insn_idx = (relo->sym_off + insn->imm) / BPF_INSN_SZ;
} else if (insn_is_pseudo_func(insn)) {
/*
* RELO_SUBPROG_ADDR relo is always emitted even if both
* functions are in the same section, so it shouldn't reach here.
*/
pr_warn("prog '%s': missing subprog addr relo for insn #%zu\n",
prog->name, insn_idx);
return -LIBBPF_ERRNO__RELOC;
} else {
/* if subprogram call is to a static function within
* the same ELF section, there won't be any relocation
* emitted, but it also means there is no additional
* offset necessary, insns->imm is relative to
* instruction's original position within the section
*/
sub_insn_idx = prog->sec_insn_off + insn_idx + insn->imm + 1;
}
/* we enforce that sub-programs should be in .text section */
subprog = find_prog_by_sec_insn(obj, obj->efile.text_shndx, sub_insn_idx);
if (!subprog) {
pr_warn("prog '%s': no .text section found yet sub-program call exists\n",
prog->name);
return -LIBBPF_ERRNO__RELOC;
}
/* if it's the first call instruction calling into this
* subprogram (meaning this subprog hasn't been processed
* yet) within the context of current main program:
* - append it at the end of main program's instructions blog;
* - process is recursively, while current program is put on hold;
* - if that subprogram calls some other not yet processes
* subprogram, same thing will happen recursively until
* there are no more unprocesses subprograms left to append
* and relocate.
*/
if (subprog->sub_insn_off == 0) {
subprog->sub_insn_off = main_prog->insns_cnt;
new_cnt = main_prog->insns_cnt + subprog->insns_cnt;
insns = libbpf_reallocarray(main_prog->insns, new_cnt, sizeof(*insns));
if (!insns) {
pr_warn("prog '%s': failed to realloc prog code\n", main_prog->name);
return -ENOMEM;
}
main_prog->insns = insns;
main_prog->insns_cnt = new_cnt;
memcpy(main_prog->insns + subprog->sub_insn_off, subprog->insns,
subprog->insns_cnt * sizeof(*insns));
pr_debug("prog '%s': added %zu insns from sub-prog '%s'\n",
main_prog->name, subprog->insns_cnt, subprog->name);
/* The subprog insns are now appended. Append its relos too. */
err = append_subprog_relos(main_prog, subprog);
if (err)
return err;
err = bpf_object__reloc_code(obj, main_prog, subprog);
if (err)
return err;
}
/* main_prog->insns memory could have been re-allocated, so
* calculate pointer again
*/
insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
/* calculate correct instruction position within current main
* prog; each main prog can have a different set of
* subprograms appended (potentially in different order as
* well), so position of any subprog can be different for
* different main programs
*/
insn->imm = subprog->sub_insn_off - (prog->sub_insn_off + insn_idx) - 1;
pr_debug("prog '%s': insn #%zu relocated, imm %d points to subprog '%s' (now at %zu offset)\n",
prog->name, insn_idx, insn->imm, subprog->name, subprog->sub_insn_off);
}
return 0;
}
/*
* Relocate sub-program calls.
*
* Algorithm operates as follows. Each entry-point BPF program (referred to as
* main prog) is processed separately. For each subprog (non-entry functions,
* that can be called from either entry progs or other subprogs) gets their
* sub_insn_off reset to zero. This serves as indicator that this subprogram
* hasn't been yet appended and relocated within current main prog. Once its
* relocated, sub_insn_off will point at the position within current main prog
* where given subprog was appended. This will further be used to relocate all
* the call instructions jumping into this subprog.
*
* We start with main program and process all call instructions. If the call
* is into a subprog that hasn't been processed (i.e., subprog->sub_insn_off
* is zero), subprog instructions are appended at the end of main program's
* instruction array. Then main program is "put on hold" while we recursively
* process newly appended subprogram. If that subprogram calls into another
* subprogram that hasn't been appended, new subprogram is appended again to
* the *main* prog's instructions (subprog's instructions are always left
* untouched, as they need to be in unmodified state for subsequent main progs
* and subprog instructions are always sent only as part of a main prog) and
* the process continues recursively. Once all the subprogs called from a main
* prog or any of its subprogs are appended (and relocated), all their
* positions within finalized instructions array are known, so it's easy to
* rewrite call instructions with correct relative offsets, corresponding to
* desired target subprog.
*
* Its important to realize that some subprogs might not be called from some
* main prog and any of its called/used subprogs. Those will keep their
* subprog->sub_insn_off as zero at all times and won't be appended to current
* main prog and won't be relocated within the context of current main prog.
* They might still be used from other main progs later.
*
* Visually this process can be shown as below. Suppose we have two main
* programs mainA and mainB and BPF object contains three subprogs: subA,
* subB, and subC. mainA calls only subA, mainB calls only subC, but subA and
* subC both call subB:
*
* +--------+ +-------+
* | v v |
* +--+---+ +--+-+-+ +---+--+
* | subA | | subB | | subC |
* +--+---+ +------+ +---+--+
* ^ ^
* | |
* +---+-------+ +------+----+
* | mainA | | mainB |
* +-----------+ +-----------+
*
* We'll start relocating mainA, will find subA, append it and start
* processing sub A recursively:
*
* +-----------+------+
* | mainA | subA |
* +-----------+------+
*
* At this point we notice that subB is used from subA, so we append it and
* relocate (there are no further subcalls from subB):
*
* +-----------+------+------+
* | mainA | subA | subB |
* +-----------+------+------+
*
* At this point, we relocate subA calls, then go one level up and finish with
* relocatin mainA calls. mainA is done.
*
* For mainB process is similar but results in different order. We start with
* mainB and skip subA and subB, as mainB never calls them (at least
* directly), but we see subC is needed, so we append and start processing it:
*
* +-----------+------+
* | mainB | subC |
* +-----------+------+
* Now we see subC needs subB, so we go back to it, append and relocate it:
*
* +-----------+------+------+
* | mainB | subC | subB |
* +-----------+------+------+
*
* At this point we unwind recursion, relocate calls in subC, then in mainB.
*/
static int
bpf_object__relocate_calls(struct bpf_object *obj, struct bpf_program *prog)
{
struct bpf_program *subprog;
int i, err;
/* mark all subprogs as not relocated (yet) within the context of
* current main program
*/
for (i = 0; i < obj->nr_programs; i++) {
subprog = &obj->programs[i];
if (!prog_is_subprog(obj, subprog))
continue;
subprog->sub_insn_off = 0;
}
err = bpf_object__reloc_code(obj, prog, prog);
if (err)
return err;
return 0;
}
static void
bpf_object__free_relocs(struct bpf_object *obj)
{
struct bpf_program *prog;
int i;
/* free up relocation descriptors */
for (i = 0; i < obj->nr_programs; i++) {
prog = &obj->programs[i];
zfree(&prog->reloc_desc);
prog->nr_reloc = 0;
}
}
static int cmp_relocs(const void *_a, const void *_b)
{
const struct reloc_desc *a = _a;
const struct reloc_desc *b = _b;
if (a->insn_idx != b->insn_idx)
return a->insn_idx < b->insn_idx ? -1 : 1;
/* no two relocations should have the same insn_idx, but ... */
if (a->type != b->type)
return a->type < b->type ? -1 : 1;
return 0;
}
static void bpf_object__sort_relos(struct bpf_object *obj)
{
int i;
for (i = 0; i < obj->nr_programs; i++) {
struct bpf_program *p = &obj->programs[i];
if (!p->nr_reloc)
continue;
qsort(p->reloc_desc, p->nr_reloc, sizeof(*p->reloc_desc), cmp_relocs);
}
}
static int
bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
{
struct bpf_program *prog;
size_t i, j;
int err;
if (obj->btf_ext) {
err = bpf_object__relocate_core(obj, targ_btf_path);
if (err) {
pr_warn("failed to perform CO-RE relocations: %d\n",
err);
return err;
}
bpf_object__sort_relos(obj);
}
/* Before relocating calls pre-process relocations and mark
* few ld_imm64 instructions that points to subprogs.
* Otherwise bpf_object__reloc_code() later would have to consider
* all ld_imm64 insns as relocation candidates. That would
* reduce relocation speed, since amount of find_prog_insn_relo()
* would increase and most of them will fail to find a relo.
*/
for (i = 0; i < obj->nr_programs; i++) {
prog = &obj->programs[i];
for (j = 0; j < prog->nr_reloc; j++) {
struct reloc_desc *relo = &prog->reloc_desc[j];
struct bpf_insn *insn = &prog->insns[relo->insn_idx];
/* mark the insn, so it's recognized by insn_is_pseudo_func() */
if (relo->type == RELO_SUBPROG_ADDR)
insn[0].src_reg = BPF_PSEUDO_FUNC;
}
}
/* relocate subprogram calls and append used subprograms to main
* programs; each copy of subprogram code needs to be relocated
* differently for each main program, because its code location might
* have changed.
* Append subprog relos to main programs to allow data relos to be
* processed after text is completely relocated.
*/
for (i = 0; i < obj->nr_programs; i++) {
prog = &obj->programs[i];
/* sub-program's sub-calls are relocated within the context of
* its main program only
*/
if (prog_is_subprog(obj, prog))
continue;
if (!prog->autoload)
continue;
err = bpf_object__relocate_calls(obj, prog);
if (err) {
pr_warn("prog '%s': failed to relocate calls: %d\n",
prog->name, err);
return err;
}
}
/* Process data relos for main programs */
for (i = 0; i < obj->nr_programs; i++) {
prog = &obj->programs[i];
if (prog_is_subprog(obj, prog))
continue;
if (!prog->autoload)
continue;
err = bpf_object__relocate_data(obj, prog);
if (err) {
pr_warn("prog '%s': failed to relocate data references: %d\n",
prog->name, err);
return err;
}
}
return 0;
}
static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
Elf64_Shdr *shdr, Elf_Data *data);
static int bpf_object__collect_map_relos(struct bpf_object *obj,
Elf64_Shdr *shdr, Elf_Data *data)
{
const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *);
int i, j, nrels, new_sz;
const struct btf_var_secinfo *vi = NULL;
const struct btf_type *sec, *var, *def;
struct bpf_map *map = NULL, *targ_map = NULL;
struct bpf_program *targ_prog = NULL;
bool is_prog_array, is_map_in_map;
const struct btf_member *member;
const char *name, *mname, *type;
unsigned int moff;
Elf64_Sym *sym;
Elf64_Rel *rel;
void *tmp;
if (!obj->efile.btf_maps_sec_btf_id || !obj->btf)
return -EINVAL;
sec = btf__type_by_id(obj->btf, obj->efile.btf_maps_sec_btf_id);
if (!sec)
return -EINVAL;
nrels = shdr->sh_size / shdr->sh_entsize;
for (i = 0; i < nrels; i++) {
rel = elf_rel_by_idx(data, i);
if (!rel) {
pr_warn(".maps relo #%d: failed to get ELF relo\n", i);
return -LIBBPF_ERRNO__FORMAT;
}
sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
if (!sym) {
pr_warn(".maps relo #%d: symbol %zx not found\n",
i, (size_t)ELF64_R_SYM(rel->r_info));
return -LIBBPF_ERRNO__FORMAT;
}
name = elf_sym_str(obj, sym->st_name) ?: "<?>";
pr_debug(".maps relo #%d: for %zd value %zd rel->r_offset %zu name %d ('%s')\n",
i, (ssize_t)(rel->r_info >> 32), (size_t)sym->st_value,
(size_t)rel->r_offset, sym->st_name, name);
for (j = 0; j < obj->nr_maps; j++) {
map = &obj->maps[j];
if (map->sec_idx != obj->efile.btf_maps_shndx)
continue;
vi = btf_var_secinfos(sec) + map->btf_var_idx;
if (vi->offset <= rel->r_offset &&
rel->r_offset + bpf_ptr_sz <= vi->offset + vi->size)
break;
}
if (j == obj->nr_maps) {
pr_warn(".maps relo #%d: cannot find map '%s' at rel->r_offset %zu\n",
i, name, (size_t)rel->r_offset);
return -EINVAL;
}
is_map_in_map = bpf_map_type__is_map_in_map(map->def.type);
is_prog_array = map->def.type == BPF_MAP_TYPE_PROG_ARRAY;
type = is_map_in_map ? "map" : "prog";
if (is_map_in_map) {
if (sym->st_shndx != obj->efile.btf_maps_shndx) {
pr_warn(".maps relo #%d: '%s' isn't a BTF-defined map\n",
i, name);
return -LIBBPF_ERRNO__RELOC;
}
if (map->def.type == BPF_MAP_TYPE_HASH_OF_MAPS &&
map->def.key_size != sizeof(int)) {
pr_warn(".maps relo #%d: hash-of-maps '%s' should have key size %zu.\n",
i, map->name, sizeof(int));
return -EINVAL;
}
targ_map = bpf_object__find_map_by_name(obj, name);
if (!targ_map) {
pr_warn(".maps relo #%d: '%s' isn't a valid map reference\n",
i, name);
return -ESRCH;
}
} else if (is_prog_array) {
targ_prog = bpf_object__find_program_by_name(obj, name);
if (!targ_prog) {
pr_warn(".maps relo #%d: '%s' isn't a valid program reference\n",
i, name);
return -ESRCH;
}
if (targ_prog->sec_idx != sym->st_shndx ||
targ_prog->sec_insn_off * 8 != sym->st_value ||
prog_is_subprog(obj, targ_prog)) {
pr_warn(".maps relo #%d: '%s' isn't an entry-point program\n",
i, name);
return -LIBBPF_ERRNO__RELOC;
}
} else {
return -EINVAL;
}
var = btf__type_by_id(obj->btf, vi->type);
def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
if (btf_vlen(def) == 0)
return -EINVAL;
member = btf_members(def) + btf_vlen(def) - 1;
mname = btf__name_by_offset(obj->btf, member->name_off);
if (strcmp(mname, "values"))
return -EINVAL;
moff = btf_member_bit_offset(def, btf_vlen(def) - 1) / 8;
if (rel->r_offset - vi->offset < moff)
return -EINVAL;
moff = rel->r_offset - vi->offset - moff;
/* here we use BPF pointer size, which is always 64 bit, as we
* are parsing ELF that was built for BPF target
*/
if (moff % bpf_ptr_sz)
return -EINVAL;
moff /= bpf_ptr_sz;
if (moff >= map->init_slots_sz) {
new_sz = moff + 1;
tmp = libbpf_reallocarray(map->init_slots, new_sz, host_ptr_sz);
if (!tmp)
return -ENOMEM;
map->init_slots = tmp;
memset(map->init_slots + map->init_slots_sz, 0,
(new_sz - map->init_slots_sz) * host_ptr_sz);
map->init_slots_sz = new_sz;
}
map->init_slots[moff] = is_map_in_map ? (void *)targ_map : (void *)targ_prog;
pr_debug(".maps relo #%d: map '%s' slot [%d] points to %s '%s'\n",
i, map->name, moff, type, name);
}
return 0;
}
static int bpf_object__collect_relos(struct bpf_object *obj)
{
int i, err;
for (i = 0; i < obj->efile.sec_cnt; i++) {
struct elf_sec_desc *sec_desc = &obj->efile.secs[i];
Elf64_Shdr *shdr;
Elf_Data *data;
int idx;
if (sec_desc->sec_type != SEC_RELO)
continue;
shdr = sec_desc->shdr;
data = sec_desc->data;
idx = shdr->sh_info;
if (shdr->sh_type != SHT_REL) {
pr_warn("internal error at %d\n", __LINE__);
return -LIBBPF_ERRNO__INTERNAL;
}
if (idx == obj->efile.st_ops_shndx)
err = bpf_object__collect_st_ops_relos(obj, shdr, data);
else if (idx == obj->efile.btf_maps_shndx)
err = bpf_object__collect_map_relos(obj, shdr, data);
else
err = bpf_object__collect_prog_relos(obj, shdr, data);
if (err)
return err;
}
bpf_object__sort_relos(obj);
return 0;
}
static bool insn_is_helper_call(struct bpf_insn *insn, enum bpf_func_id *func_id)
{
if (BPF_CLASS(insn->code) == BPF_JMP &&
BPF_OP(insn->code) == BPF_CALL &&
BPF_SRC(insn->code) == BPF_K &&
insn->src_reg == 0 &&
insn->dst_reg == 0) {
*func_id = insn->imm;
return true;
}
return false;
}
static int bpf_object__sanitize_prog(struct bpf_object *obj, struct bpf_program *prog)
{
struct bpf_insn *insn = prog->insns;
enum bpf_func_id func_id;
int i;
if (obj->gen_loader)
return 0;
for (i = 0; i < prog->insns_cnt; i++, insn++) {
if (!insn_is_helper_call(insn, &func_id))
continue;
/* on kernels that don't yet support
* bpf_probe_read_{kernel,user}[_str] helpers, fall back
* to bpf_probe_read() which works well for old kernels
*/
switch (func_id) {
case BPF_FUNC_probe_read_kernel:
case BPF_FUNC_probe_read_user:
if (!kernel_supports(obj, FEAT_PROBE_READ_KERN))
insn->imm = BPF_FUNC_probe_read;
break;
case BPF_FUNC_probe_read_kernel_str:
case BPF_FUNC_probe_read_user_str:
if (!kernel_supports(obj, FEAT_PROBE_READ_KERN))
insn->imm = BPF_FUNC_probe_read_str;
break;
default:
break;
}
}
return 0;
}
static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
int *btf_obj_fd, int *btf_type_id);
/* this is called as prog->sec_def->prog_prepare_load_fn for libbpf-supported sec_defs */
static int libbpf_prepare_prog_load(struct bpf_program *prog,
struct bpf_prog_load_opts *opts, long cookie)
{
enum sec_def_flags def = cookie;
/* old kernels might not support specifying expected_attach_type */
if ((def & SEC_EXP_ATTACH_OPT) && !kernel_supports(prog->obj, FEAT_EXP_ATTACH_TYPE))
opts->expected_attach_type = 0;
if (def & SEC_SLEEPABLE)
opts->prog_flags |= BPF_F_SLEEPABLE;
if (prog->type == BPF_PROG_TYPE_XDP && (def & SEC_XDP_FRAGS))
opts->prog_flags |= BPF_F_XDP_HAS_FRAGS;
if ((def & SEC_ATTACH_BTF) && !prog->attach_btf_id) {
int btf_obj_fd = 0, btf_type_id = 0, err;
const char *attach_name;
attach_name = strchr(prog->sec_name, '/');
if (!attach_name) {
/* if BPF program is annotated with just SEC("fentry")
* (or similar) without declaratively specifying
* target, then it is expected that target will be
* specified with bpf_program__set_attach_target() at
* runtime before BPF object load step. If not, then
* there is nothing to load into the kernel as BPF
* verifier won't be able to validate BPF program
* correctness anyways.
*/
pr_warn("prog '%s': no BTF-based attach target is specified, use bpf_program__set_attach_target()\n",
prog->name);
return -EINVAL;
}
attach_name++; /* skip over / */
err = libbpf_find_attach_btf_id(prog, attach_name, &btf_obj_fd, &btf_type_id);
if (err)
return err;
/* cache resolved BTF FD and BTF type ID in the prog */
prog->attach_btf_obj_fd = btf_obj_fd;
prog->attach_btf_id = btf_type_id;
/* but by now libbpf common logic is not utilizing
* prog->atach_btf_obj_fd/prog->attach_btf_id anymore because
* this callback is called after opts were populated by
* libbpf, so this callback has to update opts explicitly here
*/
opts->attach_btf_obj_fd = btf_obj_fd;
opts->attach_btf_id = btf_type_id;
}
return 0;
}
static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz);
static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog,
struct bpf_insn *insns, int insns_cnt,
const char *license, __u32 kern_version, int *prog_fd)
{
LIBBPF_OPTS(bpf_prog_load_opts, load_attr);
const char *prog_name = NULL;
char *cp, errmsg[STRERR_BUFSIZE];
size_t log_buf_size = 0;
char *log_buf = NULL, *tmp;
int btf_fd, ret, err;
bool own_log_buf = true;
__u32 log_level = prog->log_level;
if (prog->type == BPF_PROG_TYPE_UNSPEC) {
/*
* The program type must be set. Most likely we couldn't find a proper
* section definition at load time, and thus we didn't infer the type.
*/
pr_warn("prog '%s': missing BPF prog type, check ELF section name '%s'\n",
prog->name, prog->sec_name);
return -EINVAL;
}
if (!insns || !insns_cnt)
return -EINVAL;
load_attr.expected_attach_type = prog->expected_attach_type;
if (kernel_supports(obj, FEAT_PROG_NAME))
prog_name = prog->name;
load_attr.attach_prog_fd = prog->attach_prog_fd;
load_attr.attach_btf_obj_fd = prog->attach_btf_obj_fd;
load_attr.attach_btf_id = prog->attach_btf_id;
load_attr.kern_version = kern_version;
load_attr.prog_ifindex = prog->prog_ifindex;
/* specify func_info/line_info only if kernel supports them */
btf_fd = bpf_object__btf_fd(obj);
if (btf_fd >= 0 && kernel_supports(obj, FEAT_BTF_FUNC)) {
load_attr.prog_btf_fd = btf_fd;
load_attr.func_info = prog->func_info;
load_attr.func_info_rec_size = prog->func_info_rec_size;
load_attr.func_info_cnt = prog->func_info_cnt;
load_attr.line_info = prog->line_info;
load_attr.line_info_rec_size = prog->line_info_rec_size;
load_attr.line_info_cnt = prog->line_info_cnt;
}
load_attr.log_level = log_level;
load_attr.prog_flags = prog->prog_flags;
load_attr.fd_array = obj->fd_array;
/* adjust load_attr if sec_def provides custom preload callback */
if (prog->sec_def && prog->sec_def->prog_prepare_load_fn) {
err = prog->sec_def->prog_prepare_load_fn(prog, &load_attr, prog->sec_def->cookie);
if (err < 0) {
pr_warn("prog '%s': failed to prepare load attributes: %d\n",
prog->name, err);
return err;
}
insns = prog->insns;
insns_cnt = prog->insns_cnt;
}
if (obj->gen_loader) {
bpf_gen__prog_load(obj->gen_loader, prog->type, prog->name,
license, insns, insns_cnt, &load_attr,
prog - obj->programs);
*prog_fd = -1;
return 0;
}
retry_load:
/* if log_level is zero, we don't request logs initially even if
* custom log_buf is specified; if the program load fails, then we'll
* bump log_level to 1 and use either custom log_buf or we'll allocate
* our own and retry the load to get details on what failed
*/
if (log_level) {
if (prog->log_buf) {
log_buf = prog->log_buf;
log_buf_size = prog->log_size;
own_log_buf = false;
} else if (obj->log_buf) {
log_buf = obj->log_buf;
log_buf_size = obj->log_size;
own_log_buf = false;
} else {
log_buf_size = max((size_t)BPF_LOG_BUF_SIZE, log_buf_size * 2);
tmp = realloc(log_buf, log_buf_size);
if (!tmp) {
ret = -ENOMEM;
goto out;
}
log_buf = tmp;
log_buf[0] = '\0';
own_log_buf = true;
}
}
load_attr.log_buf = log_buf;
load_attr.log_size = log_buf_size;
load_attr.log_level = log_level;
ret = bpf_prog_load(prog->type, prog_name, license, insns, insns_cnt, &load_attr);
if (ret >= 0) {
if (log_level && own_log_buf) {
pr_debug("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
prog->name, log_buf);
}
if (obj->has_rodata && kernel_supports(obj, FEAT_PROG_BIND_MAP)) {
struct bpf_map *map;
int i;
for (i = 0; i < obj->nr_maps; i++) {
map = &prog->obj->maps[i];
if (map->libbpf_type != LIBBPF_MAP_RODATA)
continue;
if (bpf_prog_bind_map(ret, bpf_map__fd(map), NULL)) {
cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
pr_warn("prog '%s': failed to bind map '%s': %s\n",
prog->name, map->real_name, cp);
/* Don't fail hard if can't bind rodata. */
}
}
}
*prog_fd = ret;
ret = 0;
goto out;
}
if (log_level == 0) {
log_level = 1;
goto retry_load;
}
/* On ENOSPC, increase log buffer size and retry, unless custom
* log_buf is specified.
* Be careful to not overflow u32, though. Kernel's log buf size limit
* isn't part of UAPI so it can always be bumped to full 4GB. So don't
* multiply by 2 unless we are sure we'll fit within 32 bits.
* Currently, we'll get -EINVAL when we reach (UINT_MAX >> 2).
*/
if (own_log_buf && errno == ENOSPC && log_buf_size <= UINT_MAX / 2)
goto retry_load;
ret = -errno;
/* post-process verifier log to improve error descriptions */
fixup_verifier_log(prog, log_buf, log_buf_size);
cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
pr_warn("prog '%s': BPF program load failed: %s\n", prog->name, cp);
pr_perm_msg(ret);
if (own_log_buf && log_buf && log_buf[0] != '\0') {
pr_warn("prog '%s': -- BEGIN PROG LOAD LOG --\n%s-- END PROG LOAD LOG --\n",
prog->name, log_buf);
}
out:
if (own_log_buf)
free(log_buf);
return ret;
}
static char *find_prev_line(char *buf, char *cur)
{
char *p;
if (cur == buf) /* end of a log buf */
return NULL;
p = cur - 1;
while (p - 1 >= buf && *(p - 1) != '\n')
p--;
return p;
}
static void patch_log(char *buf, size_t buf_sz, size_t log_sz,
char *orig, size_t orig_sz, const char *patch)
{
/* size of the remaining log content to the right from the to-be-replaced part */
size_t rem_sz = (buf + log_sz) - (orig + orig_sz);
size_t patch_sz = strlen(patch);
if (patch_sz != orig_sz) {
/* If patch line(s) are longer than original piece of verifier log,
* shift log contents by (patch_sz - orig_sz) bytes to the right
* starting from after to-be-replaced part of the log.
*
* If patch line(s) are shorter than original piece of verifier log,
* shift log contents by (orig_sz - patch_sz) bytes to the left
* starting from after to-be-replaced part of the log
*
* We need to be careful about not overflowing available
* buf_sz capacity. If that's the case, we'll truncate the end
* of the original log, as necessary.
*/
if (patch_sz > orig_sz) {
if (orig + patch_sz >= buf + buf_sz) {
/* patch is big enough to cover remaining space completely */
patch_sz -= (orig + patch_sz) - (buf + buf_sz) + 1;
rem_sz = 0;
} else if (patch_sz - orig_sz > buf_sz - log_sz) {
/* patch causes part of remaining log to be truncated */
rem_sz -= (patch_sz - orig_sz) - (buf_sz - log_sz);
}
}
/* shift remaining log to the right by calculated amount */
memmove(orig + patch_sz, orig + orig_sz, rem_sz);
}
memcpy(orig, patch, patch_sz);
}
static void fixup_log_failed_core_relo(struct bpf_program *prog,
char *buf, size_t buf_sz, size_t log_sz,
char *line1, char *line2, char *line3)
{
/* Expected log for failed and not properly guarded CO-RE relocation:
* line1 -> 123: (85) call unknown#195896080
* line2 -> invalid func unknown#195896080
* line3 -> <anything else or end of buffer>
*
* "123" is the index of the instruction that was poisoned. We extract
* instruction index to find corresponding CO-RE relocation and
* replace this part of the log with more relevant information about
* failed CO-RE relocation.
*/
const struct bpf_core_relo *relo;
struct bpf_core_spec spec;
char patch[512], spec_buf[256];
int insn_idx, err, spec_len;
if (sscanf(line1, "%d: (%*d) call unknown#195896080\n", &insn_idx) != 1)
return;
relo = find_relo_core(prog, insn_idx);
if (!relo)
return;
err = bpf_core_parse_spec(prog->name, prog->obj->btf, relo, &spec);
if (err)
return;
spec_len = bpf_core_format_spec(spec_buf, sizeof(spec_buf), &spec);
snprintf(patch, sizeof(patch),
"%d: <invalid CO-RE relocation>\n"
"failed to resolve CO-RE relocation %s%s\n",
insn_idx, spec_buf, spec_len >= sizeof(spec_buf) ? "..." : "");
patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
}
static void fixup_log_missing_map_load(struct bpf_program *prog,
char *buf, size_t buf_sz, size_t log_sz,
char *line1, char *line2, char *line3)
{
/* Expected log for failed and not properly guarded CO-RE relocation:
* line1 -> 123: (85) call unknown#2001000345
* line2 -> invalid func unknown#2001000345
* line3 -> <anything else or end of buffer>
*
* "123" is the index of the instruction that was poisoned.
* "345" in "2001000345" are map index in obj->maps to fetch map name.
*/
struct bpf_object *obj = prog->obj;
const struct bpf_map *map;
int insn_idx, map_idx;
char patch[128];
if (sscanf(line1, "%d: (%*d) call unknown#%d\n", &insn_idx, &map_idx) != 2)
return;
map_idx -= MAP_LDIMM64_POISON_BASE;
if (map_idx < 0 || map_idx >= obj->nr_maps)
return;
map = &obj->maps[map_idx];
snprintf(patch, sizeof(patch),
"%d: <invalid BPF map reference>\n"
"BPF map '%s' is referenced but wasn't created\n",
insn_idx, map->name);
patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
}
static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz)
{
/* look for familiar error patterns in last N lines of the log */
const size_t max_last_line_cnt = 10;
char *prev_line, *cur_line, *next_line;
size_t log_sz;
int i;
if (!buf)
return;
log_sz = strlen(buf) + 1;
next_line = buf + log_sz - 1;
for (i = 0; i < max_last_line_cnt; i++, next_line = cur_line) {
cur_line = find_prev_line(buf, next_line);
if (!cur_line)
return;
/* failed CO-RE relocation case */
if (str_has_pfx(cur_line, "invalid func unknown#195896080\n")) {
prev_line = find_prev_line(buf, cur_line);
if (!prev_line)
continue;
fixup_log_failed_core_relo(prog, buf, buf_sz, log_sz,
prev_line, cur_line, next_line);
return;
} else if (str_has_pfx(cur_line, "invalid func unknown#"MAP_LDIMM64_POISON_PFX)) {
prev_line = find_prev_line(buf, cur_line);
if (!prev_line)
continue;
fixup_log_missing_map_load(prog, buf, buf_sz, log_sz,
prev_line, cur_line, next_line);
return;
}
}
}
static int bpf_program_record_relos(struct bpf_program *prog)
{
struct bpf_object *obj = prog->obj;
int i;
for (i = 0; i < prog->nr_reloc; i++) {
struct reloc_desc *relo = &prog->reloc_desc[i];
struct extern_desc *ext = &obj->externs[relo->sym_off];
switch (relo->type) {
case RELO_EXTERN_VAR:
if (ext->type != EXT_KSYM)
continue;
bpf_gen__record_extern(obj->gen_loader, ext->name,
ext->is_weak, !ext->ksym.type_id,
BTF_KIND_VAR, relo->insn_idx);
break;
case RELO_EXTERN_FUNC:
bpf_gen__record_extern(obj->gen_loader, ext->name,
ext->is_weak, false, BTF_KIND_FUNC,
relo->insn_idx);
break;
case RELO_CORE: {
struct bpf_core_relo cr = {
.insn_off = relo->insn_idx * 8,
.type_id = relo->core_relo->type_id,
.access_str_off = relo->core_relo->access_str_off,
.kind = relo->core_relo->kind,
};
bpf_gen__record_relo_core(obj->gen_loader, &cr);
break;
}
default:
continue;
}
}
return 0;
}
static int
bpf_object__load_progs(struct bpf_object *obj, int log_level)
{
struct bpf_program *prog;
size_t i;
int err;
for (i = 0; i < obj->nr_programs; i++) {
prog = &obj->programs[i];
err = bpf_object__sanitize_prog(obj, prog);
if (err)
return err;
}
for (i = 0; i < obj->nr_programs; i++) {
prog = &obj->programs[i];
if (prog_is_subprog(obj, prog))
continue;
if (!prog->autoload) {
pr_debug("prog '%s': skipped loading\n", prog->name);
continue;
}
prog->log_level |= log_level;
if (obj->gen_loader)
bpf_program_record_relos(prog);
err = bpf_object_load_prog(obj, prog, prog->insns, prog->insns_cnt,
obj->license, obj->kern_version, &prog->fd);
if (err) {
pr_warn("prog '%s': failed to load: %d\n", prog->name, err);
return err;
}
}
bpf_object__free_relocs(obj);
return 0;
}
static const struct bpf_sec_def *find_sec_def(const char *sec_name);
static int bpf_object_init_progs(struct bpf_object *obj, const struct bpf_object_open_opts *opts)
{
struct bpf_program *prog;
int err;
bpf_object__for_each_program(prog, obj) {
prog->sec_def = find_sec_def(prog->sec_name);
if (!prog->sec_def) {
/* couldn't guess, but user might manually specify */
pr_debug("prog '%s': unrecognized ELF section name '%s'\n",
prog->name, prog->sec_name);
continue;
}
prog->type = prog->sec_def->prog_type;
prog->expected_attach_type = prog->sec_def->expected_attach_type;
/* sec_def can have custom callback which should be called
* after bpf_program is initialized to adjust its properties
*/
if (prog->sec_def->prog_setup_fn) {
err = prog->sec_def->prog_setup_fn(prog, prog->sec_def->cookie);
if (err < 0) {
pr_warn("prog '%s': failed to initialize: %d\n",
prog->name, err);
return err;
}
}
}
return 0;
}
static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, size_t obj_buf_sz,
const struct bpf_object_open_opts *opts)
{
const char *obj_name, *kconfig, *btf_tmp_path;
struct bpf_object *obj;
char tmp_name[64];
int err;
char *log_buf;
size_t log_size;
__u32 log_level;
if (elf_version(EV_CURRENT) == EV_NONE) {
pr_warn("failed to init libelf for %s\n",
path ? : "(mem buf)");
return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
}
if (!OPTS_VALID(opts, bpf_object_open_opts))
return ERR_PTR(-EINVAL);
obj_name = OPTS_GET(opts, object_name, NULL);
if (obj_buf) {
if (!obj_name) {
snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
(unsigned long)obj_buf,
(unsigned long)obj_buf_sz);
obj_name = tmp_name;
}
path = obj_name;
pr_debug("loading object '%s' from buffer\n", obj_name);
}
log_buf = OPTS_GET(opts, kernel_log_buf, NULL);
log_size = OPTS_GET(opts, kernel_log_size, 0);
log_level = OPTS_GET(opts, kernel_log_level, 0);
if (log_size > UINT_MAX)
return ERR_PTR(-EINVAL);
if (log_size && !log_buf)
return ERR_PTR(-EINVAL);
obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name);
if (IS_ERR(obj))
return obj;
obj->log_buf = log_buf;
obj->log_size = log_size;
obj->log_level = log_level;
btf_tmp_path = OPTS_GET(opts, btf_custom_path, NULL);
if (btf_tmp_path) {
if (strlen(btf_tmp_path) >= PATH_MAX) {
err = -ENAMETOOLONG;
goto out;
}
obj->btf_custom_path = strdup(btf_tmp_path);
if (!obj->btf_custom_path) {
err = -ENOMEM;
goto out;
}
}
kconfig = OPTS_GET(opts, kconfig, NULL);
if (kconfig) {
obj->kconfig = strdup(kconfig);
if (!obj->kconfig) {
err = -ENOMEM;
goto out;
}
}
err = bpf_object__elf_init(obj);
err = err ? : bpf_object__check_endianness(obj);
err = err ? : bpf_object__elf_collect(obj);
err = err ? : bpf_object__collect_externs(obj);
err = err ? : bpf_object_fixup_btf(obj);
err = err ? : bpf_object__init_maps(obj, opts);
err = err ? : bpf_object_init_progs(obj, opts);
err = err ? : bpf_object__collect_relos(obj);
if (err)
goto out;
bpf_object__elf_finish(obj);
return obj;
out:
bpf_object__close(obj);
return ERR_PTR(err);
}
struct bpf_object *
bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts)
{
if (!path)
return libbpf_err_ptr(-EINVAL);
pr_debug("loading %s\n", path);
return libbpf_ptr(bpf_object_open(path, NULL, 0, opts));
}
struct bpf_object *bpf_object__open(const char *path)
{
return bpf_object__open_file(path, NULL);
}
struct bpf_object *
bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
const struct bpf_object_open_opts *opts)
{
if (!obj_buf || obj_buf_sz == 0)
return libbpf_err_ptr(-EINVAL);
return libbpf_ptr(bpf_object_open(NULL, obj_buf, obj_buf_sz, opts));
}
static int bpf_object_unload(struct bpf_object *obj)
{
size_t i;
if (!obj)
return libbpf_err(-EINVAL);
for (i = 0; i < obj->nr_maps; i++) {
zclose(obj->maps[i].fd);
if (obj->maps[i].st_ops)
zfree(&obj->maps[i].st_ops->kern_vdata);
}
for (i = 0; i < obj->nr_programs; i++)
bpf_program__unload(&obj->programs[i]);
return 0;
}
static int bpf_object__sanitize_maps(struct bpf_object *obj)
{
struct bpf_map *m;
bpf_object__for_each_map(m, obj) {
if (!bpf_map__is_internal(m))
continue;
if (!kernel_supports(obj, FEAT_ARRAY_MMAP))
m->def.map_flags &= ~BPF_F_MMAPABLE;
}
return 0;
}
int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *ctx)
{
char sym_type, sym_name[500];
unsigned long long sym_addr;
int ret, err = 0;
FILE *f;
f = fopen("/proc/kallsyms", "r");
if (!f) {
err = -errno;
pr_warn("failed to open /proc/kallsyms: %d\n", err);
return err;
}
while (true) {
ret = fscanf(f, "%llx %c %499s%*[^\n]\n",
&sym_addr, &sym_type, sym_name);
if (ret == EOF && feof(f))
break;
if (ret != 3) {
pr_warn("failed to read kallsyms entry: %d\n", ret);
err = -EINVAL;
break;
}
err = cb(sym_addr, sym_type, sym_name, ctx);
if (err)
break;
}
fclose(f);
return err;
}
static int kallsyms_cb(unsigned long long sym_addr, char sym_type,
const char *sym_name, void *ctx)
{
struct bpf_object *obj = ctx;
const struct btf_type *t;
struct extern_desc *ext;
ext = find_extern_by_name(obj, sym_name);
if (!ext || ext->type != EXT_KSYM)
return 0;
t = btf__type_by_id(obj->btf, ext->btf_id);
if (!btf_is_var(t))
return 0;
if (ext->is_set && ext->ksym.addr != sym_addr) {
pr_warn("extern (ksym) '%s': resolution is ambiguous: 0x%llx or 0x%llx\n",
sym_name, ext->ksym.addr, sym_addr);
return -EINVAL;
}
if (!ext->is_set) {
ext->is_set = true;
ext->ksym.addr = sym_addr;
pr_debug("extern (ksym) '%s': set to 0x%llx\n", sym_name, sym_addr);
}
return 0;
}
static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
{
return libbpf_kallsyms_parse(kallsyms_cb, obj);
}
static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name,
__u16 kind, struct btf **res_btf,
struct module_btf **res_mod_btf)
{
struct module_btf *mod_btf;
struct btf *btf;
int i, id, err;
btf = obj->btf_vmlinux;
mod_btf = NULL;
id = btf__find_by_name_kind(btf, ksym_name, kind);
if (id == -ENOENT) {
err = load_module_btfs(obj);
if (err)
return err;
for (i = 0; i < obj->btf_module_cnt; i++) {
/* we assume module_btf's BTF FD is always >0 */
mod_btf = &obj->btf_modules[i];
btf = mod_btf->btf;
id = btf__find_by_name_kind_own(btf, ksym_name, kind);
if (id != -ENOENT)
break;
}
}
if (id <= 0)
return -ESRCH;
*res_btf = btf;
*res_mod_btf = mod_btf;
return id;
}
static int bpf_object__resolve_ksym_var_btf_id(struct bpf_object *obj,
struct extern_desc *ext)
{
const struct btf_type *targ_var, *targ_type;
__u32 targ_type_id, local_type_id;
struct module_btf *mod_btf = NULL;
const char *targ_var_name;
struct btf *btf = NULL;
int id, err;
id = find_ksym_btf_id(obj, ext->name, BTF_KIND_VAR, &btf, &mod_btf);
if (id < 0) {
if (id == -ESRCH && ext->is_weak)
return 0;
pr_warn("extern (var ksym) '%s': not found in kernel BTF\n",
ext->name);
return id;
}
/* find local type_id */
local_type_id = ext->ksym.type_id;
/* find target type_id */
targ_var = btf__type_by_id(btf, id);
targ_var_name = btf__name_by_offset(btf, targ_var->name_off);
targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id);
err = bpf_core_types_are_compat(obj->btf, local_type_id,
btf, targ_type_id);
if (err <= 0) {
const struct btf_type *local_type;
const char *targ_name, *local_name;
local_type = btf__type_by_id(obj->btf, local_type_id);
local_name = btf__name_by_offset(obj->btf, local_type->name_off);
targ_name = btf__name_by_offset(btf, targ_type->name_off);
pr_warn("extern (var ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n",
ext->name, local_type_id,
btf_kind_str(local_type), local_name, targ_type_id,
btf_kind_str(targ_type), targ_name);
return -EINVAL;
}
ext->is_set = true;
ext->ksym.kernel_btf_obj_fd = mod_btf ? mod_btf->fd : 0;
ext->ksym.kernel_btf_id = id;
pr_debug("extern (var ksym) '%s': resolved to [%d] %s %s\n",
ext->name, id, btf_kind_str(targ_var), targ_var_name);
return 0;
}
static int bpf_object__resolve_ksym_func_btf_id(struct bpf_object *obj,
struct extern_desc *ext)
{
int local_func_proto_id, kfunc_proto_id, kfunc_id;
struct module_btf *mod_btf = NULL;
const struct btf_type *kern_func;
struct btf *kern_btf = NULL;
int ret;
local_func_proto_id = ext->ksym.type_id;
kfunc_id = find_ksym_btf_id(obj, ext->name, BTF_KIND_FUNC, &kern_btf, &mod_btf);
if (kfunc_id < 0) {
if (kfunc_id == -ESRCH && ext->is_weak)
return 0;
pr_warn("extern (func ksym) '%s': not found in kernel or module BTFs\n",
ext->name);
return kfunc_id;
}
kern_func = btf__type_by_id(kern_btf, kfunc_id);
kfunc_proto_id = kern_func->type;
ret = bpf_core_types_are_compat(obj->btf, local_func_proto_id,
kern_btf, kfunc_proto_id);
if (ret <= 0) {
pr_warn("extern (func ksym) '%s': func_proto [%d] incompatible with kernel [%d]\n",
ext->name, local_func_proto_id, kfunc_proto_id);
return -EINVAL;
}
/* set index for module BTF fd in fd_array, if unset */
if (mod_btf && !mod_btf->fd_array_idx) {
/* insn->off is s16 */
if (obj->fd_array_cnt == INT16_MAX) {
pr_warn("extern (func ksym) '%s': module BTF fd index %d too big to fit in bpf_insn offset\n",
ext->name, mod_btf->fd_array_idx);
return -E2BIG;
}
/* Cannot use index 0 for module BTF fd */
if (!obj->fd_array_cnt)
obj->fd_array_cnt = 1;
ret = libbpf_ensure_mem((void **)&obj->fd_array, &obj->fd_array_cap, sizeof(int),
obj->fd_array_cnt + 1);
if (ret)
return ret;
mod_btf->fd_array_idx = obj->fd_array_cnt;
/* we assume module BTF FD is always >0 */
obj->fd_array[obj->fd_array_cnt++] = mod_btf->fd;
}
ext->is_set = true;
ext->ksym.kernel_btf_id = kfunc_id;
ext->ksym.btf_fd_idx = mod_btf ? mod_btf->fd_array_idx : 0;
pr_debug("extern (func ksym) '%s': resolved to kernel [%d]\n",
ext->name, kfunc_id);
return 0;
}
static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
{
const struct btf_type *t;
struct extern_desc *ext;
int i, err;
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type != EXT_KSYM || !ext->ksym.type_id)
continue;
if (obj->gen_loader) {
ext->is_set = true;
ext->ksym.kernel_btf_obj_fd = 0;
ext->ksym.kernel_btf_id = 0;
continue;
}
t = btf__type_by_id(obj->btf, ext->btf_id);
if (btf_is_var(t))
err = bpf_object__resolve_ksym_var_btf_id(obj, ext);
else
err = bpf_object__resolve_ksym_func_btf_id(obj, ext);
if (err)
return err;
}
return 0;
}
static int bpf_object__resolve_externs(struct bpf_object *obj,
const char *extra_kconfig)
{
bool need_config = false, need_kallsyms = false;
bool need_vmlinux_btf = false;
struct extern_desc *ext;
void *kcfg_data = NULL;
int err, i;
if (obj->nr_extern == 0)
return 0;
if (obj->kconfig_map_idx >= 0)
kcfg_data = obj->maps[obj->kconfig_map_idx].mmaped;
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type == EXT_KSYM) {
if (ext->ksym.type_id)
need_vmlinux_btf = true;
else
need_kallsyms = true;
continue;
} else if (ext->type == EXT_KCFG) {
void *ext_ptr = kcfg_data + ext->kcfg.data_off;
__u64 value = 0;
/* Kconfig externs need actual /proc/config.gz */
if (str_has_pfx(ext->name, "CONFIG_")) {
need_config = true;
continue;
}
/* Virtual kcfg externs are customly handled by libbpf */
if (strcmp(ext->name, "LINUX_KERNEL_VERSION") == 0) {
value = get_kernel_version();
if (!value) {
pr_warn("extern (kcfg) '%s': failed to get kernel version\n", ext->name);
return -EINVAL;
}
} else if (strcmp(ext->name, "LINUX_HAS_BPF_COOKIE") == 0) {
value = kernel_supports(obj, FEAT_BPF_COOKIE);
} else if (strcmp(ext->name, "LINUX_HAS_SYSCALL_WRAPPER") == 0) {
value = kernel_supports(obj, FEAT_SYSCALL_WRAPPER);
} else if (!str_has_pfx(ext->name, "LINUX_") || !ext->is_weak) {
/* Currently libbpf supports only CONFIG_ and LINUX_ prefixed
* __kconfig externs, where LINUX_ ones are virtual and filled out
* customly by libbpf (their values don't come from Kconfig).
* If LINUX_xxx variable is not recognized by libbpf, but is marked
* __weak, it defaults to zero value, just like for CONFIG_xxx
* externs.
*/
pr_warn("extern (kcfg) '%s': unrecognized virtual extern\n", ext->name);
return -EINVAL;
}
err = set_kcfg_value_num(ext, ext_ptr, value);
if (err)
return err;
pr_debug("extern (kcfg) '%s': set to 0x%llx\n",
ext->name, (long long)value);
} else {
pr_warn("extern '%s': unrecognized extern kind\n", ext->name);
return -EINVAL;
}
}
if (need_config && extra_kconfig) {
err = bpf_object__read_kconfig_mem(obj, extra_kconfig, kcfg_data);
if (err)
return -EINVAL;
need_config = false;
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type == EXT_KCFG && !ext->is_set) {
need_config = true;
break;
}
}
}
if (need_config) {
err = bpf_object__read_kconfig_file(obj, kcfg_data);
if (err)
return -EINVAL;
}
if (need_kallsyms) {
err = bpf_object__read_kallsyms_file(obj);
if (err)
return -EINVAL;
}
if (need_vmlinux_btf) {
err = bpf_object__resolve_ksyms_btf_id(obj);
if (err)
return -EINVAL;
}
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (!ext->is_set && !ext->is_weak) {
pr_warn("extern '%s' (strong): not resolved\n", ext->name);
return -ESRCH;
} else if (!ext->is_set) {
pr_debug("extern '%s' (weak): not resolved, defaulting to zero\n",
ext->name);
}
}
return 0;
}
static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const char *target_btf_path)
{
int err, i;
if (!obj)
return libbpf_err(-EINVAL);
if (obj->loaded) {
pr_warn("object '%s': load can't be attempted twice\n", obj->name);
return libbpf_err(-EINVAL);
}
if (obj->gen_loader)
bpf_gen__init(obj->gen_loader, extra_log_level, obj->nr_programs, obj->nr_maps);
err = bpf_object__probe_loading(obj);
err = err ? : bpf_object__load_vmlinux_btf(obj, false);
err = err ? : bpf_object__resolve_externs(obj, obj->kconfig);
err = err ? : bpf_object__sanitize_and_load_btf(obj);
err = err ? : bpf_object__sanitize_maps(obj);
err = err ? : bpf_object__init_kern_struct_ops_maps(obj);
err = err ? : bpf_object__create_maps(obj);
err = err ? : bpf_object__relocate(obj, obj->btf_custom_path ? : target_btf_path);
err = err ? : bpf_object__load_progs(obj, extra_log_level);
err = err ? : bpf_object_init_prog_arrays(obj);
if (obj->gen_loader) {
/* reset FDs */
if (obj->btf)
btf__set_fd(obj->btf, -1);
for (i = 0; i < obj->nr_maps; i++)
obj->maps[i].fd = -1;
if (!err)
err = bpf_gen__finish(obj->gen_loader, obj->nr_programs, obj->nr_maps);
}
/* clean up fd_array */
zfree(&obj->fd_array);
/* clean up module BTFs */
for (i = 0; i < obj->btf_module_cnt; i++) {
close(obj->btf_modules[i].fd);
btf__free(obj->btf_modules[i].btf);
free(obj->btf_modules[i].name);
}
free(obj->btf_modules);
/* clean up vmlinux BTF */
btf__free(obj->btf_vmlinux);
obj->btf_vmlinux = NULL;
obj->loaded = true; /* doesn't matter if successfully or not */
if (err)
goto out;
return 0;
out:
/* unpin any maps that were auto-pinned during load */
for (i = 0; i < obj->nr_maps; i++)
if (obj->maps[i].pinned && !obj->maps[i].reused)
bpf_map__unpin(&obj->maps[i], NULL);
bpf_object_unload(obj);
pr_warn("failed to load object '%s'\n", obj->path);
return libbpf_err(err);
}
int bpf_object__load(struct bpf_object *obj)
{
return bpf_object_load(obj, 0, NULL);
}
static int make_parent_dir(const char *path)
{
char *cp, errmsg[STRERR_BUFSIZE];
char *dname, *dir;
int err = 0;
dname = strdup(path);
if (dname == NULL)
return -ENOMEM;
dir = dirname(dname);
if (mkdir(dir, 0700) && errno != EEXIST)
err = -errno;
free(dname);
if (err) {
cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
pr_warn("failed to mkdir %s: %s\n", path, cp);
}
return err;
}
static int check_path(const char *path)
{
char *cp, errmsg[STRERR_BUFSIZE];
struct statfs st_fs;
char *dname, *dir;
int err = 0;
if (path == NULL)
return -EINVAL;
dname = strdup(path);
if (dname == NULL)
return -ENOMEM;
dir = dirname(dname);
if (statfs(dir, &st_fs)) {
cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
pr_warn("failed to statfs %s: %s\n", dir, cp);
err = -errno;
}
free(dname);
if (!err && st_fs.f_type != BPF_FS_MAGIC) {
pr_warn("specified path %s is not on BPF FS\n", path);
err = -EINVAL;
}
return err;
}
int bpf_program__pin(struct bpf_program *prog, const char *path)
{
char *cp, errmsg[STRERR_BUFSIZE];
int err;
if (prog->fd < 0) {
pr_warn("prog '%s': can't pin program that wasn't loaded\n", prog->name);
return libbpf_err(-EINVAL);
}
err = make_parent_dir(path);
if (err)
return libbpf_err(err);
err = check_path(path);
if (err)
return libbpf_err(err);
if (bpf_obj_pin(prog->fd, path)) {
err = -errno;
cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
pr_warn("prog '%s': failed to pin at '%s': %s\n", prog->name, path, cp);
return libbpf_err(err);
}
pr_debug("prog '%s': pinned at '%s'\n", prog->name, path);
return 0;
}
int bpf_program__unpin(struct bpf_program *prog, const char *path)
{
int err;
if (prog->fd < 0) {
pr_warn("prog '%s': can't unpin program that wasn't loaded\n", prog->name);
return libbpf_err(-EINVAL);
}
err = check_path(path);
if (err)
return libbpf_err(err);
err = unlink(path);
if (err)
return libbpf_err(-errno);
pr_debug("prog '%s': unpinned from '%s'\n", prog->name, path);
return 0;
}
int bpf_map__pin(struct bpf_map *map, const char *path)
{
char *cp, errmsg[STRERR_BUFSIZE];
int err;
if (map == NULL) {
pr_warn("invalid map pointer\n");
return libbpf_err(-EINVAL);
}
if (map->pin_path) {
if (path && strcmp(path, map->pin_path)) {
pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
bpf_map__name(map), map->pin_path, path);
return libbpf_err(-EINVAL);
} else if (map->pinned) {
pr_debug("map '%s' already pinned at '%s'; not re-pinning\n",
bpf_map__name(map), map->pin_path);
return 0;
}
} else {
if (!path) {
pr_warn("missing a path to pin map '%s' at\n",
bpf_map__name(map));
return libbpf_err(-EINVAL);
} else if (map->pinned) {
pr_warn("map '%s' already pinned\n", bpf_map__name(map));
return libbpf_err(-EEXIST);
}
map->pin_path = strdup(path);
if (!map->pin_path) {
err = -errno;
goto out_err;
}
}
err = make_parent_dir(map->pin_path);
if (err)
return libbpf_err(err);
err = check_path(map->pin_path);
if (err)
return libbpf_err(err);
if (bpf_obj_pin(map->fd, map->pin_path)) {
err = -errno;
goto out_err;
}
map->pinned = true;
pr_debug("pinned map '%s'\n", map->pin_path);
return 0;
out_err:
cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
pr_warn("failed to pin map: %s\n", cp);
return libbpf_err(err);
}
int bpf_map__unpin(struct bpf_map *map, const char *path)
{
int err;
if (map == NULL) {
pr_warn("invalid map pointer\n");
return libbpf_err(-EINVAL);
}
if (map->pin_path) {
if (path && strcmp(path, map->pin_path)) {
pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
bpf_map__name(map), map->pin_path, path);
return libbpf_err(-EINVAL);
}
path = map->pin_path;
} else if (!path) {
pr_warn("no path to unpin map '%s' from\n",
bpf_map__name(map));
return libbpf_err(-EINVAL);
}
err = check_path(path);
if (err)
return libbpf_err(err);
err = unlink(path);
if (err != 0)
return libbpf_err(-errno);
map->pinned = false;
pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path);
return 0;
}
int bpf_map__set_pin_path(struct bpf_map *map, const char *path)
{
char *new = NULL;
if (path) {
new = strdup(path);
if (!new)
return libbpf_err(-errno);
}
free(map->pin_path);
map->pin_path = new;
return 0;
}
__alias(bpf_map__pin_path)
const char *bpf_map__get_pin_path(const struct bpf_map *map);
const char *bpf_map__pin_path(const struct bpf_map *map)
{
return map->pin_path;
}
bool bpf_map__is_pinned(const struct bpf_map *map)
{
return map->pinned;
}
static void sanitize_pin_path(char *s)
{
/* bpffs disallows periods in path names */
while (*s) {
if (*s == '.')
*s = '_';
s++;
}
}
int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
{
struct bpf_map *map;
int err;
if (!obj)
return libbpf_err(-ENOENT);
if (!obj->loaded) {
pr_warn("object not yet loaded; load it first\n");
return libbpf_err(-ENOENT);
}
bpf_object__for_each_map(map, obj) {
char *pin_path = NULL;
char buf[PATH_MAX];
if (!map->autocreate)
continue;
if (path) {
err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
if (err)
goto err_unpin_maps;
sanitize_pin_path(buf);
pin_path = buf;
} else if (!map->pin_path) {
continue;
}
err = bpf_map__pin(map, pin_path);
if (err)
goto err_unpin_maps;
}
return 0;
err_unpin_maps:
while ((map = bpf_object__prev_map(obj, map))) {
if (!map->pin_path)
continue;
bpf_map__unpin(map, NULL);
}
return libbpf_err(err);
}
int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
{
struct bpf_map *map;
int err;
if (!obj)
return libbpf_err(-ENOENT);
bpf_object__for_each_map(map, obj) {
char *pin_path = NULL;
char buf[PATH_MAX];
if (path) {
err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
if (err)
return libbpf_err(err);
sanitize_pin_path(buf);
pin_path = buf;
} else if (!map->pin_path) {
continue;
}
err = bpf_map__unpin(map, pin_path);
if (err)
return libbpf_err(err);
}
return 0;
}
int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
{
struct bpf_program *prog;
char buf[PATH_MAX];
int err;
if (!obj)
return libbpf_err(-ENOENT);
if (!obj->loaded) {
pr_warn("object not yet loaded; load it first\n");
return libbpf_err(-ENOENT);
}
bpf_object__for_each_program(prog, obj) {
err = pathname_concat(buf, sizeof(buf), path, prog->name);
if (err)
goto err_unpin_programs;
err = bpf_program__pin(prog, buf);
if (err)
goto err_unpin_programs;
}
return 0;
err_unpin_programs:
while ((prog = bpf_object__prev_program(obj, prog))) {
if (pathname_concat(buf, sizeof(buf), path, prog->name))
continue;
bpf_program__unpin(prog, buf);
}
return libbpf_err(err);
}
int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
{
struct bpf_program *prog;
int err;
if (!obj)
return libbpf_err(-ENOENT);
bpf_object__for_each_program(prog, obj) {
char buf[PATH_MAX];
err = pathname_concat(buf, sizeof(buf), path, prog->name);
if (err)
return libbpf_err(err);
err = bpf_program__unpin(prog, buf);
if (err)
return libbpf_err(err);
}
return 0;
}
int bpf_object__pin(struct bpf_object *obj, const char *path)
{
int err;
err = bpf_object__pin_maps(obj, path);
if (err)
return libbpf_err(err);
err = bpf_object__pin_programs(obj, path);
if (err) {
bpf_object__unpin_maps(obj, path);
return libbpf_err(err);
}
return 0;
}
static void bpf_map__destroy(struct bpf_map *map)
{
if (map->inner_map) {
bpf_map__destroy(map->inner_map);
zfree(&map->inner_map);
}
zfree(&map->init_slots);
map->init_slots_sz = 0;
if (map->mmaped) {
munmap(map->mmaped, bpf_map_mmap_sz(map));
map->mmaped = NULL;
}
if (map->st_ops) {
zfree(&map->st_ops->data);
zfree(&map->st_ops->progs);
zfree(&map->st_ops->kern_func_off);
zfree(&map->st_ops);
}
zfree(&map->name);
zfree(&map->real_name);
zfree(&map->pin_path);
if (map->fd >= 0)
zclose(map->fd);
}
void bpf_object__close(struct bpf_object *obj)
{
size_t i;
if (IS_ERR_OR_NULL(obj))
return;
usdt_manager_free(obj->usdt_man);
obj->usdt_man = NULL;
bpf_gen__free(obj->gen_loader);
bpf_object__elf_finish(obj);
bpf_object_unload(obj);
btf__free(obj->btf);
btf_ext__free(obj->btf_ext);
for (i = 0; i < obj->nr_maps; i++)
bpf_map__destroy(&obj->maps[i]);
zfree(&obj->btf_custom_path);
zfree(&obj->kconfig);
zfree(&obj->externs);
obj->nr_extern = 0;
zfree(&obj->maps);
obj->nr_maps = 0;
if (obj->programs && obj->nr_programs) {
for (i = 0; i < obj->nr_programs; i++)
bpf_program__exit(&obj->programs[i]);
}
zfree(&obj->programs);
free(obj);
}
const char *bpf_object__name(const struct bpf_object *obj)
{
return obj ? obj->name : libbpf_err_ptr(-EINVAL);
}
unsigned int bpf_object__kversion(const struct bpf_object *obj)
{
return obj ? obj->kern_version : 0;
}
struct btf *bpf_object__btf(const struct bpf_object *obj)
{
return obj ? obj->btf : NULL;
}
int bpf_object__btf_fd(const struct bpf_object *obj)
{
return obj->btf ? btf__fd(obj->btf) : -1;
}
int bpf_object__set_kversion(struct bpf_object *obj, __u32 kern_version)
{
if (obj->loaded)
return libbpf_err(-EINVAL);
obj->kern_version = kern_version;
return 0;
}
int bpf_object__gen_loader(struct bpf_object *obj, struct gen_loader_opts *opts)
{
struct bpf_gen *gen;
if (!opts)
return -EFAULT;
if (!OPTS_VALID(opts, gen_loader_opts))
return -EINVAL;
gen = calloc(sizeof(*gen), 1);
if (!gen)
return -ENOMEM;
gen->opts = opts;
obj->gen_loader = gen;
return 0;
}
static struct bpf_program *
__bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj,
bool forward)
{
size_t nr_programs = obj->nr_programs;
ssize_t idx;
if (!nr_programs)
return NULL;
if (!p)
/* Iter from the beginning */
return forward ? &obj->programs[0] :
&obj->programs[nr_programs - 1];
if (p->obj != obj) {
pr_warn("error: program handler doesn't match object\n");
return errno = EINVAL, NULL;
}
idx = (p - obj->programs) + (forward ? 1 : -1);
if (idx >= obj->nr_programs || idx < 0)
return NULL;
return &obj->programs[idx];
}
struct bpf_program *
bpf_object__next_program(const struct bpf_object *obj, struct bpf_program *prev)
{
struct bpf_program *prog = prev;
do {
prog = __bpf_program__iter(prog, obj, true);
} while (prog && prog_is_subprog(obj, prog));
return prog;
}
struct bpf_program *
bpf_object__prev_program(const struct bpf_object *obj, struct bpf_program *next)
{
struct bpf_program *prog = next;
do {
prog = __bpf_program__iter(prog, obj, false);
} while (prog && prog_is_subprog(obj, prog));
return prog;
}
void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
{
prog->prog_ifindex = ifindex;
}
const char *bpf_program__name(const struct bpf_program *prog)
{
return prog->name;
}
const char *bpf_program__section_name(const struct bpf_program *prog)
{
return prog->sec_name;
}
bool bpf_program__autoload(const struct bpf_program *prog)
{
return prog->autoload;
}
int bpf_program__set_autoload(struct bpf_program *prog, bool autoload)
{
if (prog->obj->loaded)
return libbpf_err(-EINVAL);
prog->autoload = autoload;
return 0;
}
bool bpf_program__autoattach(const struct bpf_program *prog)
{
return prog->autoattach;
}
void bpf_program__set_autoattach(struct bpf_program *prog, bool autoattach)
{
prog->autoattach = autoattach;
}
const struct bpf_insn *bpf_program__insns(const struct bpf_program *prog)
{
return prog->insns;
}
size_t bpf_program__insn_cnt(const struct bpf_program *prog)
{
return prog->insns_cnt;
}
int bpf_program__set_insns(struct bpf_program *prog,
struct bpf_insn *new_insns, size_t new_insn_cnt)
{
struct bpf_insn *insns;
if (prog->obj->loaded)
return -EBUSY;
insns = libbpf_reallocarray(prog->insns, new_insn_cnt, sizeof(*insns));
if (!insns) {
pr_warn("prog '%s': failed to realloc prog code\n", prog->name);
return -ENOMEM;
}
memcpy(insns, new_insns, new_insn_cnt * sizeof(*insns));
prog->insns = insns;
prog->insns_cnt = new_insn_cnt;
return 0;
}
int bpf_program__fd(const struct bpf_program *prog)
{
if (!prog)
return libbpf_err(-EINVAL);
if (prog->fd < 0)
return libbpf_err(-ENOENT);
return prog->fd;
}
__alias(bpf_program__type)
enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog);
enum bpf_prog_type bpf_program__type(const struct bpf_program *prog)
{
return prog->type;
}
int bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
{
if (prog->obj->loaded)
return libbpf_err(-EBUSY);
prog->type = type;
return 0;
}
__alias(bpf_program__expected_attach_type)
enum bpf_attach_type bpf_program__get_expected_attach_type(const struct bpf_program *prog);
enum bpf_attach_type bpf_program__expected_attach_type(const struct bpf_program *prog)
{
return prog->expected_attach_type;
}
int bpf_program__set_expected_attach_type(struct bpf_program *prog,
enum bpf_attach_type type)
{
if (prog->obj->loaded)
return libbpf_err(-EBUSY);
prog->expected_attach_type = type;
return 0;
}
__u32 bpf_program__flags(const struct bpf_program *prog)
{
return prog->prog_flags;
}
int bpf_program__set_flags(struct bpf_program *prog, __u32 flags)
{
if (prog->obj->loaded)
return libbpf_err(-EBUSY);
prog->prog_flags = flags;
return 0;
}
__u32 bpf_program__log_level(const struct bpf_program *prog)
{
return prog->log_level;
}
int bpf_program__set_log_level(struct bpf_program *prog, __u32 log_level)
{
if (prog->obj->loaded)
return libbpf_err(-EBUSY);
prog->log_level = log_level;
return 0;
}
const char *bpf_program__log_buf(const struct bpf_program *prog, size_t *log_size)
{
*log_size = prog->log_size;
return prog->log_buf;
}
int bpf_program__set_log_buf(struct bpf_program *prog, char *log_buf, size_t log_size)
{
if (log_size && !log_buf)
return -EINVAL;
if (prog->log_size > UINT_MAX)
return -EINVAL;
if (prog->obj->loaded)
return -EBUSY;
prog->log_buf = log_buf;
prog->log_size = log_size;
return 0;
}
#define SEC_DEF(sec_pfx, ptype, atype, flags, ...) { \
.sec = (char *)sec_pfx, \
.prog_type = BPF_PROG_TYPE_##ptype, \
.expected_attach_type = atype, \
.cookie = (long)(flags), \
.prog_prepare_load_fn = libbpf_prepare_prog_load, \
__VA_ARGS__ \
}
static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_ksyscall(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static const struct bpf_sec_def section_defs[] = {
SEC_DEF("socket", SOCKET_FILTER, 0, SEC_NONE),
SEC_DEF("sk_reuseport/migrate", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE),
SEC_DEF("sk_reuseport", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE),
SEC_DEF("kprobe+", KPROBE, 0, SEC_NONE, attach_kprobe),
SEC_DEF("uprobe+", KPROBE, 0, SEC_NONE, attach_uprobe),
SEC_DEF("uprobe.s+", KPROBE, 0, SEC_SLEEPABLE, attach_uprobe),
SEC_DEF("kretprobe+", KPROBE, 0, SEC_NONE, attach_kprobe),
SEC_DEF("uretprobe+", KPROBE, 0, SEC_NONE, attach_uprobe),
SEC_DEF("uretprobe.s+", KPROBE, 0, SEC_SLEEPABLE, attach_uprobe),
SEC_DEF("kprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
SEC_DEF("kretprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
SEC_DEF("ksyscall+", KPROBE, 0, SEC_NONE, attach_ksyscall),
SEC_DEF("kretsyscall+", KPROBE, 0, SEC_NONE, attach_ksyscall),
SEC_DEF("usdt+", KPROBE, 0, SEC_NONE, attach_usdt),
SEC_DEF("tc", SCHED_CLS, 0, SEC_NONE),
SEC_DEF("classifier", SCHED_CLS, 0, SEC_NONE),
SEC_DEF("action", SCHED_ACT, 0, SEC_NONE),
SEC_DEF("tracepoint+", TRACEPOINT, 0, SEC_NONE, attach_tp),
SEC_DEF("tp+", TRACEPOINT, 0, SEC_NONE, attach_tp),
SEC_DEF("raw_tracepoint+", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
SEC_DEF("raw_tp+", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
SEC_DEF("raw_tracepoint.w+", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
SEC_DEF("raw_tp.w+", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
SEC_DEF("tp_btf+", TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("fentry+", TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("fmod_ret+", TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("fexit+", TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("fentry.s+", TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
SEC_DEF("fmod_ret.s+", TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
SEC_DEF("fexit.s+", TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_trace),
SEC_DEF("freplace+", EXT, 0, SEC_ATTACH_BTF, attach_trace),
SEC_DEF("lsm+", LSM, BPF_LSM_MAC, SEC_ATTACH_BTF, attach_lsm),
SEC_DEF("lsm.s+", LSM, BPF_LSM_MAC, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_lsm),
SEC_DEF("lsm_cgroup+", LSM, BPF_LSM_CGROUP, SEC_ATTACH_BTF),
SEC_DEF("iter+", TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF, attach_iter),
SEC_DEF("iter.s+", TRACING, BPF_TRACE_ITER, SEC_ATTACH_BTF | SEC_SLEEPABLE, attach_iter),
SEC_DEF("syscall", SYSCALL, 0, SEC_SLEEPABLE),
SEC_DEF("xdp.frags/devmap", XDP, BPF_XDP_DEVMAP, SEC_XDP_FRAGS),
SEC_DEF("xdp/devmap", XDP, BPF_XDP_DEVMAP, SEC_ATTACHABLE),
SEC_DEF("xdp.frags/cpumap", XDP, BPF_XDP_CPUMAP, SEC_XDP_FRAGS),
SEC_DEF("xdp/cpumap", XDP, BPF_XDP_CPUMAP, SEC_ATTACHABLE),
SEC_DEF("xdp.frags", XDP, BPF_XDP, SEC_XDP_FRAGS),
SEC_DEF("xdp", XDP, BPF_XDP, SEC_ATTACHABLE_OPT),
SEC_DEF("perf_event", PERF_EVENT, 0, SEC_NONE),
SEC_DEF("lwt_in", LWT_IN, 0, SEC_NONE),
SEC_DEF("lwt_out", LWT_OUT, 0, SEC_NONE),
SEC_DEF("lwt_xmit", LWT_XMIT, 0, SEC_NONE),
SEC_DEF("lwt_seg6local", LWT_SEG6LOCAL, 0, SEC_NONE),
SEC_DEF("sockops", SOCK_OPS, BPF_CGROUP_SOCK_OPS, SEC_ATTACHABLE_OPT),
SEC_DEF("sk_skb/stream_parser", SK_SKB, BPF_SK_SKB_STREAM_PARSER, SEC_ATTACHABLE_OPT),
SEC_DEF("sk_skb/stream_verdict",SK_SKB, BPF_SK_SKB_STREAM_VERDICT, SEC_ATTACHABLE_OPT),
SEC_DEF("sk_skb", SK_SKB, 0, SEC_NONE),
SEC_DEF("sk_msg", SK_MSG, BPF_SK_MSG_VERDICT, SEC_ATTACHABLE_OPT),
SEC_DEF("lirc_mode2", LIRC_MODE2, BPF_LIRC_MODE2, SEC_ATTACHABLE_OPT),
SEC_DEF("flow_dissector", FLOW_DISSECTOR, BPF_FLOW_DISSECTOR, SEC_ATTACHABLE_OPT),
SEC_DEF("cgroup_skb/ingress", CGROUP_SKB, BPF_CGROUP_INET_INGRESS, SEC_ATTACHABLE_OPT),
SEC_DEF("cgroup_skb/egress", CGROUP_SKB, BPF_CGROUP_INET_EGRESS, SEC_ATTACHABLE_OPT),
SEC_DEF("cgroup/skb", CGROUP_SKB, 0, SEC_NONE),
SEC_DEF("cgroup/sock_create", CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE, SEC_ATTACHABLE),
SEC_DEF("cgroup/sock_release", CGROUP_SOCK, BPF_CGROUP_INET_SOCK_RELEASE, SEC_ATTACHABLE),
SEC_DEF("cgroup/sock", CGROUP_SOCK, BPF_CGROUP_INET_SOCK_CREATE, SEC_ATTACHABLE_OPT),
SEC_DEF("cgroup/post_bind4", CGROUP_SOCK, BPF_CGROUP_INET4_POST_BIND, SEC_ATTACHABLE),
SEC_DEF("cgroup/post_bind6", CGROUP_SOCK, BPF_CGROUP_INET6_POST_BIND, SEC_ATTACHABLE),
SEC_DEF("cgroup/bind4", CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_BIND, SEC_ATTACHABLE),
SEC_DEF("cgroup/bind6", CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_BIND, SEC_ATTACHABLE),
SEC_DEF("cgroup/connect4", CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_CONNECT, SEC_ATTACHABLE),
SEC_DEF("cgroup/connect6", CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_CONNECT, SEC_ATTACHABLE),
SEC_DEF("cgroup/sendmsg4", CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_SENDMSG, SEC_ATTACHABLE),
SEC_DEF("cgroup/sendmsg6", CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_SENDMSG, SEC_ATTACHABLE),
SEC_DEF("cgroup/recvmsg4", CGROUP_SOCK_ADDR, BPF_CGROUP_UDP4_RECVMSG, SEC_ATTACHABLE),
SEC_DEF("cgroup/recvmsg6", CGROUP_SOCK_ADDR, BPF_CGROUP_UDP6_RECVMSG, SEC_ATTACHABLE),
SEC_DEF("cgroup/getpeername4", CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETPEERNAME, SEC_ATTACHABLE),
SEC_DEF("cgroup/getpeername6", CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETPEERNAME, SEC_ATTACHABLE),
SEC_DEF("cgroup/getsockname4", CGROUP_SOCK_ADDR, BPF_CGROUP_INET4_GETSOCKNAME, SEC_ATTACHABLE),
SEC_DEF("cgroup/getsockname6", CGROUP_SOCK_ADDR, BPF_CGROUP_INET6_GETSOCKNAME, SEC_ATTACHABLE),
SEC_DEF("cgroup/sysctl", CGROUP_SYSCTL, BPF_CGROUP_SYSCTL, SEC_ATTACHABLE),
SEC_DEF("cgroup/getsockopt", CGROUP_SOCKOPT, BPF_CGROUP_GETSOCKOPT, SEC_ATTACHABLE),
SEC_DEF("cgroup/setsockopt", CGROUP_SOCKOPT, BPF_CGROUP_SETSOCKOPT, SEC_ATTACHABLE),
SEC_DEF("cgroup/dev", CGROUP_DEVICE, BPF_CGROUP_DEVICE, SEC_ATTACHABLE_OPT),
SEC_DEF("struct_ops+", STRUCT_OPS, 0, SEC_NONE),
SEC_DEF("struct_ops.s+", STRUCT_OPS, 0, SEC_SLEEPABLE),
SEC_DEF("sk_lookup", SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE),
};
static size_t custom_sec_def_cnt;
static struct bpf_sec_def *custom_sec_defs;
static struct bpf_sec_def custom_fallback_def;
static bool has_custom_fallback_def;
static int last_custom_sec_def_handler_id;
int libbpf_register_prog_handler(const char *sec,
enum bpf_prog_type prog_type,
enum bpf_attach_type exp_attach_type,
const struct libbpf_prog_handler_opts *opts)
{
struct bpf_sec_def *sec_def;
if (!OPTS_VALID(opts, libbpf_prog_handler_opts))
return libbpf_err(-EINVAL);
if (last_custom_sec_def_handler_id == INT_MAX) /* prevent overflow */
return libbpf_err(-E2BIG);
if (sec) {
sec_def = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt + 1,
sizeof(*sec_def));
if (!sec_def)
return libbpf_err(-ENOMEM);
custom_sec_defs = sec_def;
sec_def = &custom_sec_defs[custom_sec_def_cnt];
} else {
if (has_custom_fallback_def)
return libbpf_err(-EBUSY);
sec_def = &custom_fallback_def;
}
sec_def->sec = sec ? strdup(sec) : NULL;
if (sec && !sec_def->sec)
return libbpf_err(-ENOMEM);
sec_def->prog_type = prog_type;
sec_def->expected_attach_type = exp_attach_type;
sec_def->cookie = OPTS_GET(opts, cookie, 0);
sec_def->prog_setup_fn = OPTS_GET(opts, prog_setup_fn, NULL);
sec_def->prog_prepare_load_fn = OPTS_GET(opts, prog_prepare_load_fn, NULL);
sec_def->prog_attach_fn = OPTS_GET(opts, prog_attach_fn, NULL);
sec_def->handler_id = ++last_custom_sec_def_handler_id;
if (sec)
custom_sec_def_cnt++;
else
has_custom_fallback_def = true;
return sec_def->handler_id;
}
int libbpf_unregister_prog_handler(int handler_id)
{
struct bpf_sec_def *sec_defs;
int i;
if (handler_id <= 0)
return libbpf_err(-EINVAL);
if (has_custom_fallback_def && custom_fallback_def.handler_id == handler_id) {
memset(&custom_fallback_def, 0, sizeof(custom_fallback_def));
has_custom_fallback_def = false;
return 0;
}
for (i = 0; i < custom_sec_def_cnt; i++) {
if (custom_sec_defs[i].handler_id == handler_id)
break;
}
if (i == custom_sec_def_cnt)
return libbpf_err(-ENOENT);
free(custom_sec_defs[i].sec);
for (i = i + 1; i < custom_sec_def_cnt; i++)
custom_sec_defs[i - 1] = custom_sec_defs[i];
custom_sec_def_cnt--;
/* try to shrink the array, but it's ok if we couldn't */
sec_defs = libbpf_reallocarray(custom_sec_defs, custom_sec_def_cnt, sizeof(*sec_defs));
if (sec_defs)
custom_sec_defs = sec_defs;
return 0;
}
static bool sec_def_matches(const struct bpf_sec_def *sec_def, const char *sec_name)
{
size_t len = strlen(sec_def->sec);
/* "type/" always has to have proper SEC("type/extras") form */
if (sec_def->sec[len - 1] == '/') {
if (str_has_pfx(sec_name, sec_def->sec))
return true;
return false;
}
/* "type+" means it can be either exact SEC("type") or
* well-formed SEC("type/extras") with proper '/' separator
*/
if (sec_def->sec[len - 1] == '+') {
len--;
/* not even a prefix */
if (strncmp(sec_name, sec_def->sec, len) != 0)
return false;
/* exact match or has '/' separator */
if (sec_name[len] == '\0' || sec_name[len] == '/')
return true;
return false;
}
return strcmp(sec_name, sec_def->sec) == 0;
}
static const struct bpf_sec_def *find_sec_def(const char *sec_name)
{
const struct bpf_sec_def *sec_def;
int i, n;
n = custom_sec_def_cnt;
for (i = 0; i < n; i++) {
sec_def = &custom_sec_defs[i];
if (sec_def_matches(sec_def, sec_name))
return sec_def;
}
n = ARRAY_SIZE(section_defs);
for (i = 0; i < n; i++) {
sec_def = &section_defs[i];
if (sec_def_matches(sec_def, sec_name))
return sec_def;
}
if (has_custom_fallback_def)
return &custom_fallback_def;
return NULL;
}
#define MAX_TYPE_NAME_SIZE 32
static char *libbpf_get_type_names(bool attach_type)
{
int i, len = ARRAY_SIZE(section_defs) * MAX_TYPE_NAME_SIZE;
char *buf;
buf = malloc(len);
if (!buf)
return NULL;
buf[0] = '\0';
/* Forge string buf with all available names */
for (i = 0; i < ARRAY_SIZE(section_defs); i++) {
const struct bpf_sec_def *sec_def = &section_defs[i];
if (attach_type) {
if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
continue;
if (!(sec_def->cookie & SEC_ATTACHABLE))
continue;
}
if (strlen(buf) + strlen(section_defs[i].sec) + 2 > len) {
free(buf);
return NULL;
}
strcat(buf, " ");
strcat(buf, section_defs[i].sec);
}
return buf;
}
int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
enum bpf_attach_type *expected_attach_type)
{
const struct bpf_sec_def *sec_def;
char *type_names;
if (!name)
return libbpf_err(-EINVAL);
sec_def = find_sec_def(name);
if (sec_def) {
*prog_type = sec_def->prog_type;
*expected_attach_type = sec_def->expected_attach_type;
return 0;
}
pr_debug("failed to guess program type from ELF section '%s'\n", name);
type_names = libbpf_get_type_names(false);
if (type_names != NULL) {
pr_debug("supported section(type) names are:%s\n", type_names);
free(type_names);
}
return libbpf_err(-ESRCH);
}
const char *libbpf_bpf_attach_type_str(enum bpf_attach_type t)
{
if (t < 0 || t >= ARRAY_SIZE(attach_type_name))
return NULL;
return attach_type_name[t];
}
const char *libbpf_bpf_link_type_str(enum bpf_link_type t)
{
if (t < 0 || t >= ARRAY_SIZE(link_type_name))
return NULL;
return link_type_name[t];
}
const char *libbpf_bpf_map_type_str(enum bpf_map_type t)
{
if (t < 0 || t >= ARRAY_SIZE(map_type_name))
return NULL;
return map_type_name[t];
}
const char *libbpf_bpf_prog_type_str(enum bpf_prog_type t)
{
if (t < 0 || t >= ARRAY_SIZE(prog_type_name))
return NULL;
return prog_type_name[t];
}
static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,
size_t offset)
{
struct bpf_map *map;
size_t i;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
if (!bpf_map__is_struct_ops(map))
continue;
if (map->sec_offset <= offset &&
offset - map->sec_offset < map->def.value_size)
return map;
}
return NULL;
}
/* Collect the reloc from ELF and populate the st_ops->progs[] */
static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
Elf64_Shdr *shdr, Elf_Data *data)
{
const struct btf_member *member;
struct bpf_struct_ops *st_ops;
struct bpf_program *prog;
unsigned int shdr_idx;
const struct btf *btf;
struct bpf_map *map;
unsigned int moff, insn_idx;
const char *name;
__u32 member_idx;
Elf64_Sym *sym;
Elf64_Rel *rel;
int i, nrels;
btf = obj->btf;
nrels = shdr->sh_size / shdr->sh_entsize;
for (i = 0; i < nrels; i++) {
rel = elf_rel_by_idx(data, i);
if (!rel) {
pr_warn("struct_ops reloc: failed to get %d reloc\n", i);
return -LIBBPF_ERRNO__FORMAT;
}
sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
if (!sym) {
pr_warn("struct_ops reloc: symbol %zx not found\n",
(size_t)ELF64_R_SYM(rel->r_info));
return -LIBBPF_ERRNO__FORMAT;
}
name = elf_sym_str(obj, sym->st_name) ?: "<?>";
map = find_struct_ops_map_by_offset(obj, rel->r_offset);
if (!map) {
pr_warn("struct_ops reloc: cannot find map at rel->r_offset %zu\n",
(size_t)rel->r_offset);
return -EINVAL;
}
moff = rel->r_offset - map->sec_offset;
shdr_idx = sym->st_shndx;
st_ops = map->st_ops;
pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel->r_offset %zu map->sec_offset %zu name %d (\'%s\')\n",
map->name,
(long long)(rel->r_info >> 32),
(long long)sym->st_value,
shdr_idx, (size_t)rel->r_offset,
map->sec_offset, sym->st_name, name);
if (shdr_idx >= SHN_LORESERVE) {
pr_warn("struct_ops reloc %s: rel->r_offset %zu shdr_idx %u unsupported non-static function\n",
map->name, (size_t)rel->r_offset, shdr_idx);
return -LIBBPF_ERRNO__RELOC;
}
if (sym->st_value % BPF_INSN_SZ) {
pr_warn("struct_ops reloc %s: invalid target program offset %llu\n",
map->name, (unsigned long long)sym->st_value);
return -LIBBPF_ERRNO__FORMAT;
}
insn_idx = sym->st_value / BPF_INSN_SZ;
member = find_member_by_offset(st_ops->type, moff * 8);
if (!member) {
pr_warn("struct_ops reloc %s: cannot find member at moff %u\n",
map->name, moff);
return -EINVAL;
}
member_idx = member - btf_members(st_ops->type);
name = btf__name_by_offset(btf, member->name_off);
if (!resolve_func_ptr(btf, member->type, NULL)) {
pr_warn("struct_ops reloc %s: cannot relocate non func ptr %s\n",
map->name, name);
return -EINVAL;
}
prog = find_prog_by_sec_insn(obj, shdr_idx, insn_idx);
if (!prog) {
pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n",
map->name, shdr_idx, name);
return -EINVAL;
}
/* prevent the use of BPF prog with invalid type */
if (prog->type != BPF_PROG_TYPE_STRUCT_OPS) {
pr_warn("struct_ops reloc %s: prog %s is not struct_ops BPF program\n",
map->name, prog->name);
return -EINVAL;
}
/* if we haven't yet processed this BPF program, record proper
* attach_btf_id and member_idx
*/
if (!prog->attach_btf_id) {
prog->attach_btf_id = st_ops->type_id;
prog->expected_attach_type = member_idx;
}
/* struct_ops BPF prog can be re-used between multiple
* .struct_ops as long as it's the same struct_ops struct
* definition and the same function pointer field
*/
if (prog->attach_btf_id != st_ops->type_id ||
prog->expected_attach_type != member_idx) {
pr_warn("struct_ops reloc %s: cannot use prog %s in sec %s with type %u attach_btf_id %u expected_attach_type %u for func ptr %s\n",
map->name, prog->name, prog->sec_name, prog->type,
prog->attach_btf_id, prog->expected_attach_type, name);
return -EINVAL;
}
st_ops->progs[member_idx] = prog;
}
return 0;
}
#define BTF_TRACE_PREFIX "btf_trace_"
#define BTF_LSM_PREFIX "bpf_lsm_"
#define BTF_ITER_PREFIX "bpf_iter_"
#define BTF_MAX_NAME_SIZE 128
void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
const char **prefix, int *kind)
{
switch (attach_type) {
case BPF_TRACE_RAW_TP:
*prefix = BTF_TRACE_PREFIX;
*kind = BTF_KIND_TYPEDEF;
break;
case BPF_LSM_MAC:
case BPF_LSM_CGROUP:
*prefix = BTF_LSM_PREFIX;
*kind = BTF_KIND_FUNC;
break;
case BPF_TRACE_ITER:
*prefix = BTF_ITER_PREFIX;
*kind = BTF_KIND_FUNC;
break;
default:
*prefix = "";
*kind = BTF_KIND_FUNC;
}
}
static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
const char *name, __u32 kind)
{
char btf_type_name[BTF_MAX_NAME_SIZE];
int ret;
ret = snprintf(btf_type_name, sizeof(btf_type_name),
"%s%s", prefix, name);
/* snprintf returns the number of characters written excluding the
* terminating null. So, if >= BTF_MAX_NAME_SIZE are written, it
* indicates truncation.
*/
if (ret < 0 || ret >= sizeof(btf_type_name))
return -ENAMETOOLONG;
return btf__find_by_name_kind(btf, btf_type_name, kind);
}
static inline int find_attach_btf_id(struct btf *btf, const char *name,
enum bpf_attach_type attach_type)
{
const char *prefix;
int kind;
btf_get_kernel_prefix_kind(attach_type, &prefix, &kind);
return find_btf_by_prefix_kind(btf, prefix, name, kind);
}
int libbpf_find_vmlinux_btf_id(const char *name,
enum bpf_attach_type attach_type)
{
struct btf *btf;
int err;
btf = btf__load_vmlinux_btf();
err = libbpf_get_error(btf);
if (err) {
pr_warn("vmlinux BTF is not found\n");
return libbpf_err(err);
}
err = find_attach_btf_id(btf, name, attach_type);
if (err <= 0)
pr_warn("%s is not found in vmlinux BTF\n", name);
btf__free(btf);
return libbpf_err(err);
}
static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
{
struct bpf_prog_info info;
__u32 info_len = sizeof(info);
struct btf *btf;
int err;
memset(&info, 0, info_len);
err = bpf_prog_get_info_by_fd(attach_prog_fd, &info, &info_len);
if (err) {
pr_warn("failed bpf_prog_get_info_by_fd for FD %d: %d\n",
attach_prog_fd, err);
return err;
}
err = -EINVAL;
if (!info.btf_id) {
pr_warn("The target program doesn't have BTF\n");
goto out;
}
btf = btf__load_from_kernel_by_id(info.btf_id);
err = libbpf_get_error(btf);
if (err) {
pr_warn("Failed to get BTF %d of the program: %d\n", info.btf_id, err);
goto out;
}
err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
btf__free(btf);
if (err <= 0) {
pr_warn("%s is not found in prog's BTF\n", name);
goto out;
}
out:
return err;
}
static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name,
enum bpf_attach_type attach_type,
int *btf_obj_fd, int *btf_type_id)
{
int ret, i;
ret = find_attach_btf_id(obj->btf_vmlinux, attach_name, attach_type);
if (ret > 0) {
*btf_obj_fd = 0; /* vmlinux BTF */
*btf_type_id = ret;
return 0;
}
if (ret != -ENOENT)
return ret;
ret = load_module_btfs(obj);
if (ret)
return ret;
for (i = 0; i < obj->btf_module_cnt; i++) {
const struct module_btf *mod = &obj->btf_modules[i];
ret = find_attach_btf_id(mod->btf, attach_name, attach_type);
if (ret > 0) {
*btf_obj_fd = mod->fd;
*btf_type_id = ret;
return 0;
}
if (ret == -ENOENT)
continue;
return ret;
}
return -ESRCH;
}
static int libbpf_find_attach_btf_id(struct bpf_program *prog, const char *attach_name,
int *btf_obj_fd, int *btf_type_id)
{
enum bpf_attach_type attach_type = prog->expected_attach_type;
__u32 attach_prog_fd = prog->attach_prog_fd;
int err = 0;
/* BPF program's BTF ID */
if (prog->type == BPF_PROG_TYPE_EXT || attach_prog_fd) {
if (!attach_prog_fd) {
pr_warn("prog '%s': attach program FD is not set\n", prog->name);
return -EINVAL;
}
err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
if (err < 0) {
pr_warn("prog '%s': failed to find BPF program (FD %d) BTF ID for '%s': %d\n",
prog->name, attach_prog_fd, attach_name, err);
return err;
}
*btf_obj_fd = 0;
*btf_type_id = err;
return 0;
}
/* kernel/module BTF ID */
if (prog->obj->gen_loader) {
bpf_gen__record_attach_target(prog->obj->gen_loader, attach_name, attach_type);
*btf_obj_fd = 0;
*btf_type_id = 1;
} else {
err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id);
}
if (err) {
pr_warn("prog '%s': failed to find kernel BTF type ID of '%s': %d\n",
prog->name, attach_name, err);
return err;
}
return 0;
}
int libbpf_attach_type_by_name(const char *name,
enum bpf_attach_type *attach_type)
{
char *type_names;
const struct bpf_sec_def *sec_def;
if (!name)
return libbpf_err(-EINVAL);
sec_def = find_sec_def(name);
if (!sec_def) {
pr_debug("failed to guess attach type based on ELF section name '%s'\n", name);
type_names = libbpf_get_type_names(true);
if (type_names != NULL) {
pr_debug("attachable section(type) names are:%s\n", type_names);
free(type_names);
}
return libbpf_err(-EINVAL);
}
if (sec_def->prog_prepare_load_fn != libbpf_prepare_prog_load)
return libbpf_err(-EINVAL);
if (!(sec_def->cookie & SEC_ATTACHABLE))
return libbpf_err(-EINVAL);
*attach_type = sec_def->expected_attach_type;
return 0;
}
int bpf_map__fd(const struct bpf_map *map)
{
return map ? map->fd : libbpf_err(-EINVAL);
}
static bool map_uses_real_name(const struct bpf_map *map)
{
/* Since libbpf started to support custom .data.* and .rodata.* maps,
* their user-visible name differs from kernel-visible name. Users see
* such map's corresponding ELF section name as a map name.
* This check distinguishes .data/.rodata from .data.* and .rodata.*
* maps to know which name has to be returned to the user.
*/
if (map->libbpf_type == LIBBPF_MAP_DATA && strcmp(map->real_name, DATA_SEC) != 0)
return true;
if (map->libbpf_type == LIBBPF_MAP_RODATA && strcmp(map->real_name, RODATA_SEC) != 0)
return true;
return false;
}
const char *bpf_map__name(const struct bpf_map *map)
{
if (!map)
return NULL;
if (map_uses_real_name(map))
return map->real_name;
return map->name;
}
enum bpf_map_type bpf_map__type(const struct bpf_map *map)
{
return map->def.type;
}
int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type)
{
if (map->fd >= 0)
return libbpf_err(-EBUSY);
map->def.type = type;
return 0;
}
__u32 bpf_map__map_flags(const struct bpf_map *map)
{
return map->def.map_flags;
}
int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags)
{
if (map->fd >= 0)
return libbpf_err(-EBUSY);
map->def.map_flags = flags;
return 0;
}
__u64 bpf_map__map_extra(const struct bpf_map *map)
{
return map->map_extra;
}
int bpf_map__set_map_extra(struct bpf_map *map, __u64 map_extra)
{
if (map->fd >= 0)
return libbpf_err(-EBUSY);
map->map_extra = map_extra;
return 0;
}
__u32 bpf_map__numa_node(const struct bpf_map *map)
{
return map->numa_node;
}
int bpf_map__set_numa_node(struct bpf_map *map, __u32 numa_node)
{
if (map->fd >= 0)
return libbpf_err(-EBUSY);
map->numa_node = numa_node;
return 0;
}
__u32 bpf_map__key_size(const struct bpf_map *map)
{
return map->def.key_size;
}
int bpf_map__set_key_size(struct bpf_map *map, __u32 size)
{
if (map->fd >= 0)
return libbpf_err(-EBUSY);
map->def.key_size = size;
return 0;
}
__u32 bpf_map__value_size(const struct bpf_map *map)
{
return map->def.value_size;
}
int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
{
if (map->fd >= 0)
return libbpf_err(-EBUSY);
map->def.value_size = size;
return 0;
}
__u32 bpf_map__btf_key_type_id(const struct bpf_map *map)
{
return map ? map->btf_key_type_id : 0;
}
__u32 bpf_map__btf_value_type_id(const struct bpf_map *map)
{
return map ? map->btf_value_type_id : 0;
}
int bpf_map__set_initial_value(struct bpf_map *map,
const void *data, size_t size)
{
if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG ||
size != map->def.value_size || map->fd >= 0)
return libbpf_err(-EINVAL);
memcpy(map->mmaped, data, size);
return 0;
}
const void *bpf_map__initial_value(struct bpf_map *map, size_t *psize)
{
if (!map->mmaped)
return NULL;
*psize = map->def.value_size;
return map->mmaped;
}
bool bpf_map__is_internal(const struct bpf_map *map)
{
return map->libbpf_type != LIBBPF_MAP_UNSPEC;
}
__u32 bpf_map__ifindex(const struct bpf_map *map)
{
return map->map_ifindex;
}
int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
{
if (map->fd >= 0)
return libbpf_err(-EBUSY);
map->map_ifindex = ifindex;
return 0;
}
int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
{
if (!bpf_map_type__is_map_in_map(map->def.type)) {
pr_warn("error: unsupported map type\n");
return libbpf_err(-EINVAL);
}
if (map->inner_map_fd != -1) {
pr_warn("error: inner_map_fd already specified\n");
return libbpf_err(-EINVAL);
}
if (map->inner_map) {
bpf_map__destroy(map->inner_map);
zfree(&map->inner_map);
}
map->inner_map_fd = fd;
return 0;
}
static struct bpf_map *
__bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
{
ssize_t idx;
struct bpf_map *s, *e;
if (!obj || !obj->maps)
return errno = EINVAL, NULL;
s = obj->maps;
e = obj->maps + obj->nr_maps;
if ((m < s) || (m >= e)) {
pr_warn("error in %s: map handler doesn't belong to object\n",
__func__);
return errno = EINVAL, NULL;
}
idx = (m - obj->maps) + i;
if (idx >= obj->nr_maps || idx < 0)
return NULL;
return &obj->maps[idx];
}
struct bpf_map *
bpf_object__next_map(const struct bpf_object *obj, const struct bpf_map *prev)
{
if (prev == NULL)
return obj->maps;
return __bpf_map__iter(prev, obj, 1);
}
struct bpf_map *
bpf_object__prev_map(const struct bpf_object *obj, const struct bpf_map *next)
{
if (next == NULL) {
if (!obj->nr_maps)
return NULL;
return obj->maps + obj->nr_maps - 1;
}
return __bpf_map__iter(next, obj, -1);
}
struct bpf_map *
bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
{
struct bpf_map *pos;
bpf_object__for_each_map(pos, obj) {
/* if it's a special internal map name (which always starts
* with dot) then check if that special name matches the
* real map name (ELF section name)
*/
if (name[0] == '.') {
if (pos->real_name && strcmp(pos->real_name, name) == 0)
return pos;
continue;
}
/* otherwise map name has to be an exact match */
if (map_uses_real_name(pos)) {
if (strcmp(pos->real_name, name) == 0)
return pos;
continue;
}
if (strcmp(pos->name, name) == 0)
return pos;
}
return errno = ENOENT, NULL;
}
int
bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name)
{
return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
}
static int validate_map_op(const struct bpf_map *map, size_t key_sz,
size_t value_sz, bool check_value_sz)
{
if (map->fd <= 0)
return -ENOENT;
if (map->def.key_size != key_sz) {
pr_warn("map '%s': unexpected key size %zu provided, expected %u\n",
map->name, key_sz, map->def.key_size);
return -EINVAL;
}
if (!check_value_sz)
return 0;
switch (map->def.type) {
case BPF_MAP_TYPE_PERCPU_ARRAY:
case BPF_MAP_TYPE_PERCPU_HASH:
case BPF_MAP_TYPE_LRU_PERCPU_HASH:
case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: {
int num_cpu = libbpf_num_possible_cpus();
size_t elem_sz = roundup(map->def.value_size, 8);
if (value_sz != num_cpu * elem_sz) {
pr_warn("map '%s': unexpected value size %zu provided for per-CPU map, expected %d * %zu = %zd\n",
map->name, value_sz, num_cpu, elem_sz, num_cpu * elem_sz);
return -EINVAL;
}
break;
}
default:
if (map->def.value_size != value_sz) {
pr_warn("map '%s': unexpected value size %zu provided, expected %u\n",
map->name, value_sz, map->def.value_size);
return -EINVAL;
}
break;
}
return 0;
}
int bpf_map__lookup_elem(const struct bpf_map *map,
const void *key, size_t key_sz,
void *value, size_t value_sz, __u64 flags)
{
int err;
err = validate_map_op(map, key_sz, value_sz, true);
if (err)
return libbpf_err(err);
return bpf_map_lookup_elem_flags(map->fd, key, value, flags);
}
int bpf_map__update_elem(const struct bpf_map *map,
const void *key, size_t key_sz,
const void *value, size_t value_sz, __u64 flags)
{
int err;
err = validate_map_op(map, key_sz, value_sz, true);
if (err)
return libbpf_err(err);
return bpf_map_update_elem(map->fd, key, value, flags);
}
int bpf_map__delete_elem(const struct bpf_map *map,
const void *key, size_t key_sz, __u64 flags)
{
int err;
err = validate_map_op(map, key_sz, 0, false /* check_value_sz */);
if (err)
return libbpf_err(err);
return bpf_map_delete_elem_flags(map->fd, key, flags);
}
int bpf_map__lookup_and_delete_elem(const struct bpf_map *map,
const void *key, size_t key_sz,
void *value, size_t value_sz, __u64 flags)
{
int err;
err = validate_map_op(map, key_sz, value_sz, true);
if (err)
return libbpf_err(err);
return bpf_map_lookup_and_delete_elem_flags(map->fd, key, value, flags);
}
int bpf_map__get_next_key(const struct bpf_map *map,
const void *cur_key, void *next_key, size_t key_sz)
{
int err;
err = validate_map_op(map, key_sz, 0, false /* check_value_sz */);
if (err)
return libbpf_err(err);
return bpf_map_get_next_key(map->fd, cur_key, next_key);
}
long libbpf_get_error(const void *ptr)
{
if (!IS_ERR_OR_NULL(ptr))
return 0;
if (IS_ERR(ptr))
errno = -PTR_ERR(ptr);
/* If ptr == NULL, then errno should be already set by the failing
* API, because libbpf never returns NULL on success and it now always
* sets errno on error. So no extra errno handling for ptr == NULL
* case.
*/
return -errno;
}
/* Replace link's underlying BPF program with the new one */
int bpf_link__update_program(struct bpf_link *link, struct bpf_program *prog)
{
int ret;
ret = bpf_link_update(bpf_link__fd(link), bpf_program__fd(prog), NULL);
return libbpf_err_errno(ret);
}
/* Release "ownership" of underlying BPF resource (typically, BPF program
* attached to some BPF hook, e.g., tracepoint, kprobe, etc). Disconnected
* link, when destructed through bpf_link__destroy() call won't attempt to
* detach/unregisted that BPF resource. This is useful in situations where,
* say, attached BPF program has to outlive userspace program that attached it
* in the system. Depending on type of BPF program, though, there might be
* additional steps (like pinning BPF program in BPF FS) necessary to ensure
* exit of userspace program doesn't trigger automatic detachment and clean up
* inside the kernel.
*/
void bpf_link__disconnect(struct bpf_link *link)
{
link->disconnected = true;
}
int bpf_link__destroy(struct bpf_link *link)
{
int err = 0;
if (IS_ERR_OR_NULL(link))
return 0;
if (!link->disconnected && link->detach)
err = link->detach(link);
if (link->pin_path)
free(link->pin_path);
if (link->dealloc)
link->dealloc(link);
else
free(link);
return libbpf_err(err);
}
int bpf_link__fd(const struct bpf_link *link)
{
return link->fd;
}
const char *bpf_link__pin_path(const struct bpf_link *link)
{
return link->pin_path;
}
static int bpf_link__detach_fd(struct bpf_link *link)
{
return libbpf_err_errno(close(link->fd));
}
struct bpf_link *bpf_link__open(const char *path)
{
struct bpf_link *link;
int fd;
fd = bpf_obj_get(path);
if (fd < 0) {
fd = -errno;
pr_warn("failed to open link at %s: %d\n", path, fd);
return libbpf_err_ptr(fd);
}
link = calloc(1, sizeof(*link));
if (!link) {
close(fd);
return libbpf_err_ptr(-ENOMEM);
}
link->detach = &bpf_link__detach_fd;
link->fd = fd;
link->pin_path = strdup(path);
if (!link->pin_path) {
bpf_link__destroy(link);
return libbpf_err_ptr(-ENOMEM);
}
return link;
}
int bpf_link__detach(struct bpf_link *link)
{
return bpf_link_detach(link->fd) ? -errno : 0;
}
int bpf_link__pin(struct bpf_link *link, const char *path)
{
int err;
if (link->pin_path)
return libbpf_err(-EBUSY);
err = make_parent_dir(path);
if (err)
return libbpf_err(err);
err = check_path(path);
if (err)
return libbpf_err(err);
link->pin_path = strdup(path);
if (!link->pin_path)
return libbpf_err(-ENOMEM);
if (bpf_obj_pin(link->fd, link->pin_path)) {
err = -errno;
zfree(&link->pin_path);
return libbpf_err(err);
}
pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path);
return 0;
}
int bpf_link__unpin(struct bpf_link *link)
{
int err;
if (!link->pin_path)
return libbpf_err(-EINVAL);
err = unlink(link->pin_path);
if (err != 0)
return -errno;
pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path);
zfree(&link->pin_path);
return 0;
}
struct bpf_link_perf {
struct bpf_link link;
int perf_event_fd;
/* legacy kprobe support: keep track of probe identifier and type */
char *legacy_probe_name;
bool legacy_is_kprobe;
bool legacy_is_retprobe;
};
static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe);
static int remove_uprobe_event_legacy(const char *probe_name, bool retprobe);
static int bpf_link_perf_detach(struct bpf_link *link)
{
struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
int err = 0;
if (ioctl(perf_link->perf_event_fd, PERF_EVENT_IOC_DISABLE, 0) < 0)
err = -errno;
if (perf_link->perf_event_fd != link->fd)
close(perf_link->perf_event_fd);
close(link->fd);
/* legacy uprobe/kprobe needs to be removed after perf event fd closure */
if (perf_link->legacy_probe_name) {
if (perf_link->legacy_is_kprobe) {
err = remove_kprobe_event_legacy(perf_link->legacy_probe_name,
perf_link->legacy_is_retprobe);
} else {
err = remove_uprobe_event_legacy(perf_link->legacy_probe_name,
perf_link->legacy_is_retprobe);
}
}
return err;
}
static void bpf_link_perf_dealloc(struct bpf_link *link)
{
struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
free(perf_link->legacy_probe_name);
free(perf_link);
}
struct bpf_link *bpf_program__attach_perf_event_opts(const struct bpf_program *prog, int pfd,
const struct bpf_perf_event_opts *opts)
{
char errmsg[STRERR_BUFSIZE];
struct bpf_link_perf *link;
int prog_fd, link_fd = -1, err;
if (!OPTS_VALID(opts, bpf_perf_event_opts))
return libbpf_err_ptr(-EINVAL);
if (pfd < 0) {
pr_warn("prog '%s': invalid perf event FD %d\n",
prog->name, pfd);
return libbpf_err_ptr(-EINVAL);
}
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
prog->name);
return libbpf_err_ptr(-EINVAL);
}
link = calloc(1, sizeof(*link));
if (!link)
return libbpf_err_ptr(-ENOMEM);
link->link.detach = &bpf_link_perf_detach;
link->link.dealloc = &bpf_link_perf_dealloc;
link->perf_event_fd = pfd;
if (kernel_supports(prog->obj, FEAT_PERF_LINK)) {
DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts,
.perf_event.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0));
link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, &link_opts);
if (link_fd < 0) {
err = -errno;
pr_warn("prog '%s': failed to create BPF link for perf_event FD %d: %d (%s)\n",
prog->name, pfd,
err, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto err_out;
}
link->link.fd = link_fd;
} else {
if (OPTS_GET(opts, bpf_cookie, 0)) {
pr_warn("prog '%s': user context value is not supported\n", prog->name);
err = -EOPNOTSUPP;
goto err_out;
}
if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
err = -errno;
pr_warn("prog '%s': failed to attach to perf_event FD %d: %s\n",
prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
if (err == -EPROTO)
pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
prog->name, pfd);
goto err_out;
}
link->link.fd = pfd;
}
if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
err = -errno;
pr_warn("prog '%s': failed to enable perf_event FD %d: %s\n",
prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto err_out;
}
return &link->link;
err_out:
if (link_fd >= 0)
close(link_fd);
free(link);
return libbpf_err_ptr(err);
}
struct bpf_link *bpf_program__attach_perf_event(const struct bpf_program *prog, int pfd)
{
return bpf_program__attach_perf_event_opts(prog, pfd, NULL);
}
/*
* this function is expected to parse integer in the range of [0, 2^31-1] from
* given file using scanf format string fmt. If actual parsed value is
* negative, the result might be indistinguishable from error
*/
static int parse_uint_from_file(const char *file, const char *fmt)
{
char buf[STRERR_BUFSIZE];
int err, ret;
FILE *f;
f = fopen(file, "r");
if (!f) {
err = -errno;
pr_debug("failed to open '%s': %s\n", file,
libbpf_strerror_r(err, buf, sizeof(buf)));
return err;
}
err = fscanf(f, fmt, &ret);
if (err != 1) {
err = err == EOF ? -EIO : -errno;
pr_debug("failed to parse '%s': %s\n", file,
libbpf_strerror_r(err, buf, sizeof(buf)));
fclose(f);
return err;
}
fclose(f);
return ret;
}
static int determine_kprobe_perf_type(void)
{
const char *file = "/sys/bus/event_source/devices/kprobe/type";
return parse_uint_from_file(file, "%d\n");
}
static int determine_uprobe_perf_type(void)
{
const char *file = "/sys/bus/event_source/devices/uprobe/type";
return parse_uint_from_file(file, "%d\n");
}
static int determine_kprobe_retprobe_bit(void)
{
const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe";
return parse_uint_from_file(file, "config:%d\n");
}
static int determine_uprobe_retprobe_bit(void)
{
const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe";
return parse_uint_from_file(file, "config:%d\n");
}
#define PERF_UPROBE_REF_CTR_OFFSET_BITS 32
#define PERF_UPROBE_REF_CTR_OFFSET_SHIFT 32
static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
uint64_t offset, int pid, size_t ref_ctr_off)
{
const size_t attr_sz = sizeof(struct perf_event_attr);
struct perf_event_attr attr;
char errmsg[STRERR_BUFSIZE];
int type, pfd;
if ((__u64)ref_ctr_off >= (1ULL << PERF_UPROBE_REF_CTR_OFFSET_BITS))
return -EINVAL;
memset(&attr, 0, attr_sz);
type = uprobe ? determine_uprobe_perf_type()
: determine_kprobe_perf_type();
if (type < 0) {
pr_warn("failed to determine %s perf type: %s\n",
uprobe ? "uprobe" : "kprobe",
libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
return type;
}
if (retprobe) {
int bit = uprobe ? determine_uprobe_retprobe_bit()
: determine_kprobe_retprobe_bit();
if (bit < 0) {
pr_warn("failed to determine %s retprobe bit: %s\n",
uprobe ? "uprobe" : "kprobe",
libbpf_strerror_r(bit, errmsg, sizeof(errmsg)));
return bit;
}
attr.config |= 1 << bit;
}
attr.size = attr_sz;
attr.type = type;
attr.config |= (__u64)ref_ctr_off << PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
attr.config2 = offset; /* kprobe_addr or probe_offset */
/* pid filter is meaningful only for uprobes */
pfd = syscall(__NR_perf_event_open, &attr,
pid < 0 ? -1 : pid /* pid */,
pid == -1 ? 0 : -1 /* cpu */,
-1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
return pfd >= 0 ? pfd : -errno;
}
static int append_to_file(const char *file, const char *fmt, ...)
{
int fd, n, err = 0;
va_list ap;
fd = open(file, O_WRONLY | O_APPEND | O_CLOEXEC, 0);
if (fd < 0)
return -errno;
va_start(ap, fmt);
n = vdprintf(fd, fmt, ap);
va_end(ap);
if (n < 0)
err = -errno;
close(fd);
return err;
}
#define DEBUGFS "/sys/kernel/debug/tracing"
#define TRACEFS "/sys/kernel/tracing"
static bool use_debugfs(void)
{
static int has_debugfs = -1;
if (has_debugfs < 0)
has_debugfs = faccessat(AT_FDCWD, DEBUGFS, F_OK, AT_EACCESS) == 0;
return has_debugfs == 1;
}
static const char *tracefs_path(void)
{
return use_debugfs() ? DEBUGFS : TRACEFS;
}
static const char *tracefs_kprobe_events(void)
{
return use_debugfs() ? DEBUGFS"/kprobe_events" : TRACEFS"/kprobe_events";
}
static const char *tracefs_uprobe_events(void)
{
return use_debugfs() ? DEBUGFS"/uprobe_events" : TRACEFS"/uprobe_events";
}
static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz,
const char *kfunc_name, size_t offset)
{
static int index = 0;
int i;
snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx_%d", getpid(), kfunc_name, offset,
__sync_fetch_and_add(&index, 1));
/* sanitize binary_path in the probe name */
for (i = 0; buf[i]; i++) {
if (!isalnum(buf[i]))
buf[i] = '_';
}
}
static int add_kprobe_event_legacy(const char *probe_name, bool retprobe,
const char *kfunc_name, size_t offset)
{
return append_to_file(tracefs_kprobe_events(), "%c:%s/%s %s+0x%zx",
retprobe ? 'r' : 'p',
retprobe ? "kretprobes" : "kprobes",
probe_name, kfunc_name, offset);
}
static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe)
{
return append_to_file(tracefs_kprobe_events(), "-:%s/%s",
retprobe ? "kretprobes" : "kprobes", probe_name);
}
static int determine_kprobe_perf_type_legacy(const char *probe_name, bool retprobe)
{
char file[256];
snprintf(file, sizeof(file), "%s/events/%s/%s/id",
tracefs_path(), retprobe ? "kretprobes" : "kprobes", probe_name);
return parse_uint_from_file(file, "%d\n");
}
static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe,
const char *kfunc_name, size_t offset, int pid)
{
const size_t attr_sz = sizeof(struct perf_event_attr);
struct perf_event_attr attr;
char errmsg[STRERR_BUFSIZE];
int type, pfd, err;
err = add_kprobe_event_legacy(probe_name, retprobe, kfunc_name, offset);
if (err < 0) {
pr_warn("failed to add legacy kprobe event for '%s+0x%zx': %s\n",
kfunc_name, offset,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
return err;
}
type = determine_kprobe_perf_type_legacy(probe_name, retprobe);
if (type < 0) {
err = type;
pr_warn("failed to determine legacy kprobe event id for '%s+0x%zx': %s\n",
kfunc_name, offset,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto err_clean_legacy;
}
memset(&attr, 0, attr_sz);
attr.size = attr_sz;
attr.config = type;
attr.type = PERF_TYPE_TRACEPOINT;
pfd = syscall(__NR_perf_event_open, &attr,
pid < 0 ? -1 : pid, /* pid */
pid == -1 ? 0 : -1, /* cpu */
-1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
if (pfd < 0) {
err = -errno;
pr_warn("legacy kprobe perf_event_open() failed: %s\n",
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto err_clean_legacy;
}
return pfd;
err_clean_legacy:
/* Clear the newly added legacy kprobe_event */
remove_kprobe_event_legacy(probe_name, retprobe);
return err;
}
static const char *arch_specific_syscall_pfx(void)
{
#if defined(__x86_64__)
return "x64";
#elif defined(__i386__)
return "ia32";
#elif defined(__s390x__)
return "s390x";
#elif defined(__s390__)
return "s390";
#elif defined(__arm__)
return "arm";
#elif defined(__aarch64__)
return "arm64";
#elif defined(__mips__)
return "mips";
#elif defined(__riscv)
return "riscv";
#elif defined(__powerpc__)
return "powerpc";
#elif defined(__powerpc64__)
return "powerpc64";
#else
return NULL;
#endif
}
static int probe_kern_syscall_wrapper(void)
{
char syscall_name[64];
const char *ksys_pfx;
ksys_pfx = arch_specific_syscall_pfx();
if (!ksys_pfx)
return 0;
snprintf(syscall_name, sizeof(syscall_name), "__%s_sys_bpf", ksys_pfx);
if (determine_kprobe_perf_type() >= 0) {
int pfd;
pfd = perf_event_open_probe(false, false, syscall_name, 0, getpid(), 0);
if (pfd >= 0)
close(pfd);
return pfd >= 0 ? 1 : 0;
} else { /* legacy mode */
char probe_name[128];
gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name), syscall_name, 0);
if (add_kprobe_event_legacy(probe_name, false, syscall_name, 0) < 0)
return 0;
(void)remove_kprobe_event_legacy(probe_name, false);
return 1;
}
}
struct bpf_link *
bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
const char *func_name,
const struct bpf_kprobe_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE];
char *legacy_probe = NULL;
struct bpf_link *link;
size_t offset;
bool retprobe, legacy;
int pfd, err;
if (!OPTS_VALID(opts, bpf_kprobe_opts))
return libbpf_err_ptr(-EINVAL);
retprobe = OPTS_GET(opts, retprobe, false);
offset = OPTS_GET(opts, offset, 0);
pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
legacy = determine_kprobe_perf_type() < 0;
if (!legacy) {
pfd = perf_event_open_probe(false /* uprobe */, retprobe,
func_name, offset,
-1 /* pid */, 0 /* ref_ctr_off */);
} else {
char probe_name[256];
gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name),
func_name, offset);
legacy_probe = strdup(probe_name);
if (!legacy_probe)
return libbpf_err_ptr(-ENOMEM);
pfd = perf_event_kprobe_open_legacy(legacy_probe, retprobe, func_name,
offset, -1 /* pid */);
}
if (pfd < 0) {
err = -errno;
pr_warn("prog '%s': failed to create %s '%s+0x%zx' perf event: %s\n",
prog->name, retprobe ? "kretprobe" : "kprobe",
func_name, offset,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto err_out;
}
link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
pr_warn("prog '%s': failed to attach to %s '%s+0x%zx': %s\n",
prog->name, retprobe ? "kretprobe" : "kprobe",
func_name, offset,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto err_clean_legacy;
}
if (legacy) {
struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
perf_link->legacy_probe_name = legacy_probe;
perf_link->legacy_is_kprobe = true;
perf_link->legacy_is_retprobe = retprobe;
}
return link;
err_clean_legacy:
if (legacy)
remove_kprobe_event_legacy(legacy_probe, retprobe);
err_out:
free(legacy_probe);
return libbpf_err_ptr(err);
}
struct bpf_link *bpf_program__attach_kprobe(const struct bpf_program *prog,
bool retprobe,
const char *func_name)
{
DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
.retprobe = retprobe,
);
return bpf_program__attach_kprobe_opts(prog, func_name, &opts);
}
struct bpf_link *bpf_program__attach_ksyscall(const struct bpf_program *prog,
const char *syscall_name,
const struct bpf_ksyscall_opts *opts)
{
LIBBPF_OPTS(bpf_kprobe_opts, kprobe_opts);
char func_name[128];
if (!OPTS_VALID(opts, bpf_ksyscall_opts))
return libbpf_err_ptr(-EINVAL);
if (kernel_supports(prog->obj, FEAT_SYSCALL_WRAPPER)) {
/* arch_specific_syscall_pfx() should never return NULL here
* because it is guarded by kernel_supports(). However, since
* compiler does not know that we have an explicit conditional
* as well.
*/
snprintf(func_name, sizeof(func_name), "__%s_sys_%s",
arch_specific_syscall_pfx() ? : "", syscall_name);
} else {
snprintf(func_name, sizeof(func_name), "__se_sys_%s", syscall_name);
}
kprobe_opts.retprobe = OPTS_GET(opts, retprobe, false);
kprobe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
return bpf_program__attach_kprobe_opts(prog, func_name, &kprobe_opts);
}
/* Adapted from perf/util/string.c */
static bool glob_match(const char *str, const char *pat)
{
while (*str && *pat && *pat != '*') {
if (*pat == '?') { /* Matches any single character */
str++;
pat++;
continue;
}
if (*str != *pat)
return false;
str++;
pat++;
}
/* Check wild card */
if (*pat == '*') {
while (*pat == '*')
pat++;
if (!*pat) /* Tail wild card matches all */
return true;
while (*str)
if (glob_match(str++, pat))
return true;
}
return !*str && !*pat;
}
struct kprobe_multi_resolve {
const char *pattern;
unsigned long *addrs;
size_t cap;
size_t cnt;
};
static int
resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type,
const char *sym_name, void *ctx)
{
struct kprobe_multi_resolve *res = ctx;
int err;
if (!glob_match(sym_name, res->pattern))
return 0;
err = libbpf_ensure_mem((void **) &res->addrs, &res->cap, sizeof(unsigned long),
res->cnt + 1);
if (err)
return err;
res->addrs[res->cnt++] = (unsigned long) sym_addr;
return 0;
}
struct bpf_link *
bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
const char *pattern,
const struct bpf_kprobe_multi_opts *opts)
{
LIBBPF_OPTS(bpf_link_create_opts, lopts);
struct kprobe_multi_resolve res = {
.pattern = pattern,
};
struct bpf_link *link = NULL;
char errmsg[STRERR_BUFSIZE];
const unsigned long *addrs;
int err, link_fd, prog_fd;
const __u64 *cookies;
const char **syms;
bool retprobe;
size_t cnt;
if (!OPTS_VALID(opts, bpf_kprobe_multi_opts))
return libbpf_err_ptr(-EINVAL);
syms = OPTS_GET(opts, syms, false);
addrs = OPTS_GET(opts, addrs, false);
cnt = OPTS_GET(opts, cnt, false);
cookies = OPTS_GET(opts, cookies, false);
if (!pattern && !addrs && !syms)
return libbpf_err_ptr(-EINVAL);
if (pattern && (addrs || syms || cookies || cnt))
return libbpf_err_ptr(-EINVAL);
if (!pattern && !cnt)
return libbpf_err_ptr(-EINVAL);
if (addrs && syms)
return libbpf_err_ptr(-EINVAL);
if (pattern) {
err = libbpf_kallsyms_parse(resolve_kprobe_multi_cb, &res);
if (err)
goto error;
if (!res.cnt) {
err = -ENOENT;
goto error;
}
addrs = res.addrs;
cnt = res.cnt;
}
retprobe = OPTS_GET(opts, retprobe, false);
lopts.kprobe_multi.syms = syms;
lopts.kprobe_multi.addrs = addrs;
lopts.kprobe_multi.cookies = cookies;
lopts.kprobe_multi.cnt = cnt;
lopts.kprobe_multi.flags = retprobe ? BPF_F_KPROBE_MULTI_RETURN : 0;
link = calloc(1, sizeof(*link));
if (!link) {
err = -ENOMEM;
goto error;
}
link->detach = &bpf_link__detach_fd;
prog_fd = bpf_program__fd(prog);
link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_KPROBE_MULTI, &lopts);
if (link_fd < 0) {
err = -errno;
pr_warn("prog '%s': failed to attach: %s\n",
prog->name, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto error;
}
link->fd = link_fd;
free(res.addrs);
return link;
error:
free(link);
free(res.addrs);
return libbpf_err_ptr(err);
}
static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts);
unsigned long offset = 0;
const char *func_name;
char *func;
int n;
*link = NULL;
/* no auto-attach for SEC("kprobe") and SEC("kretprobe") */
if (strcmp(prog->sec_name, "kprobe") == 0 || strcmp(prog->sec_name, "kretprobe") == 0)
return 0;
opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe/");
if (opts.retprobe)
func_name = prog->sec_name + sizeof("kretprobe/") - 1;
else
func_name = prog->sec_name + sizeof("kprobe/") - 1;
n = sscanf(func_name, "%m[a-zA-Z0-9_.]+%li", &func, &offset);
if (n < 1) {
pr_warn("kprobe name is invalid: %s\n", func_name);
return -EINVAL;
}
if (opts.retprobe && offset != 0) {
free(func);
pr_warn("kretprobes do not support offset specification\n");
return -EINVAL;
}
opts.offset = offset;
*link = bpf_program__attach_kprobe_opts(prog, func, &opts);
free(func);
return libbpf_get_error(*link);
}
static int attach_ksyscall(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
LIBBPF_OPTS(bpf_ksyscall_opts, opts);
const char *syscall_name;
*link = NULL;
/* no auto-attach for SEC("ksyscall") and SEC("kretsyscall") */
if (strcmp(prog->sec_name, "ksyscall") == 0 || strcmp(prog->sec_name, "kretsyscall") == 0)
return 0;
opts.retprobe = str_has_pfx(prog->sec_name, "kretsyscall/");
if (opts.retprobe)
syscall_name = prog->sec_name + sizeof("kretsyscall/") - 1;
else
syscall_name = prog->sec_name + sizeof("ksyscall/") - 1;
*link = bpf_program__attach_ksyscall(prog, syscall_name, &opts);
return *link ? 0 : -errno;
}
static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
const char *spec;
char *pattern;
int n;
*link = NULL;
/* no auto-attach for SEC("kprobe.multi") and SEC("kretprobe.multi") */
if (strcmp(prog->sec_name, "kprobe.multi") == 0 ||
strcmp(prog->sec_name, "kretprobe.multi") == 0)
return 0;
opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe.multi/");
if (opts.retprobe)
spec = prog->sec_name + sizeof("kretprobe.multi/") - 1;
else
spec = prog->sec_name + sizeof("kprobe.multi/") - 1;
n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
if (n < 1) {
pr_warn("kprobe multi pattern is invalid: %s\n", pattern);
return -EINVAL;
}
*link = bpf_program__attach_kprobe_multi_opts(prog, pattern, &opts);
free(pattern);
return libbpf_get_error(*link);
}
static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
const char *binary_path, uint64_t offset)
{
int i;
snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx", getpid(), binary_path, (size_t)offset);
/* sanitize binary_path in the probe name */
for (i = 0; buf[i]; i++) {
if (!isalnum(buf[i]))
buf[i] = '_';
}
}
static inline int add_uprobe_event_legacy(const char *probe_name, bool retprobe,
const char *binary_path, size_t offset)
{
return append_to_file(tracefs_uprobe_events(), "%c:%s/%s %s:0x%zx",
retprobe ? 'r' : 'p',
retprobe ? "uretprobes" : "uprobes",
probe_name, binary_path, offset);
}
static inline int remove_uprobe_event_legacy(const char *probe_name, bool retprobe)
{
return append_to_file(tracefs_uprobe_events(), "-:%s/%s",
retprobe ? "uretprobes" : "uprobes", probe_name);
}
static int determine_uprobe_perf_type_legacy(const char *probe_name, bool retprobe)
{
char file[512];
snprintf(file, sizeof(file), "%s/events/%s/%s/id",
tracefs_path(), retprobe ? "uretprobes" : "uprobes", probe_name);
return parse_uint_from_file(file, "%d\n");
}
static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
const char *binary_path, size_t offset, int pid)
{
const size_t attr_sz = sizeof(struct perf_event_attr);
struct perf_event_attr attr;
int type, pfd, err;
err = add_uprobe_event_legacy(probe_name, retprobe, binary_path, offset);
if (err < 0) {
pr_warn("failed to add legacy uprobe event for %s:0x%zx: %d\n",
binary_path, (size_t)offset, err);
return err;
}
type = determine_uprobe_perf_type_legacy(probe_name, retprobe);
if (type < 0) {
err = type;
pr_warn("failed to determine legacy uprobe event id for %s:0x%zx: %d\n",
binary_path, offset, err);
goto err_clean_legacy;
}
memset(&attr, 0, attr_sz);
attr.size = attr_sz;
attr.config = type;
attr.type = PERF_TYPE_TRACEPOINT;
pfd = syscall(__NR_perf_event_open, &attr,
pid < 0 ? -1 : pid, /* pid */
pid == -1 ? 0 : -1, /* cpu */
-1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
if (pfd < 0) {
err = -errno;
pr_warn("legacy uprobe perf_event_open() failed: %d\n", err);
goto err_clean_legacy;
}
return pfd;
err_clean_legacy:
/* Clear the newly added legacy uprobe_event */
remove_uprobe_event_legacy(probe_name, retprobe);
return err;
}
/* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn)
{
while ((scn = elf_nextscn(elf, scn)) != NULL) {
GElf_Shdr sh;
if (!gelf_getshdr(scn, &sh))
continue;
if (sh.sh_type == sh_type)
return scn;
}
return NULL;
}
/* Find offset of function name in object specified by path. "name" matches
* symbol name or name@@LIB for library functions.
*/
static long elf_find_func_offset(const char *binary_path, const char *name)
{
int fd, i, sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
bool is_shared_lib, is_name_qualified;
char errmsg[STRERR_BUFSIZE];
long ret = -ENOENT;
size_t name_len;
GElf_Ehdr ehdr;
Elf *elf;
fd = open(binary_path, O_RDONLY | O_CLOEXEC);
if (fd < 0) {
ret = -errno;
pr_warn("failed to open %s: %s\n", binary_path,
libbpf_strerror_r(ret, errmsg, sizeof(errmsg)));
return ret;
}
elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
if (!elf) {
pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
close(fd);
return -LIBBPF_ERRNO__FORMAT;
}
if (!gelf_getehdr(elf, &ehdr)) {
pr_warn("elf: failed to get ehdr from %s: %s\n", binary_path, elf_errmsg(-1));
ret = -LIBBPF_ERRNO__FORMAT;
goto out;
}
/* for shared lib case, we do not need to calculate relative offset */
is_shared_lib = ehdr.e_type == ET_DYN;
name_len = strlen(name);
/* Does name specify "@@LIB"? */
is_name_qualified = strstr(name, "@@") != NULL;
/* Search SHT_DYNSYM, SHT_SYMTAB for symbol. This search order is used because if
* a binary is stripped, it may only have SHT_DYNSYM, and a fully-statically
* linked binary may not have SHT_DYMSYM, so absence of a section should not be
* reported as a warning/error.
*/
for (i = 0; i < ARRAY_SIZE(sh_types); i++) {
size_t nr_syms, strtabidx, idx;
Elf_Data *symbols = NULL;
Elf_Scn *scn = NULL;
int last_bind = -1;
const char *sname;
GElf_Shdr sh;
scn = elf_find_next_scn_by_type(elf, sh_types[i], NULL);
if (!scn) {
pr_debug("elf: failed to find symbol table ELF sections in '%s'\n",
binary_path);
continue;
}
if (!gelf_getshdr(scn, &sh))
continue;
strtabidx = sh.sh_link;
symbols = elf_getdata(scn, 0);
if (!symbols) {
pr_warn("elf: failed to get symbols for symtab section in '%s': %s\n",
binary_path, elf_errmsg(-1));
ret = -LIBBPF_ERRNO__FORMAT;
goto out;
}
nr_syms = symbols->d_size / sh.sh_entsize;
for (idx = 0; idx < nr_syms; idx++) {
int curr_bind;
GElf_Sym sym;
Elf_Scn *sym_scn;
GElf_Shdr sym_sh;
if (!gelf_getsym(symbols, idx, &sym))
continue;
if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
continue;
sname = elf_strptr(elf, strtabidx, sym.st_name);
if (!sname)
continue;
curr_bind = GELF_ST_BIND(sym.st_info);
/* User can specify func, func@@LIB or func@@LIB_VERSION. */
if (strncmp(sname, name, name_len) != 0)
continue;
/* ...but we don't want a search for "foo" to match 'foo2" also, so any
* additional characters in sname should be of the form "@@LIB".
*/
if (!is_name_qualified && sname[name_len] != '\0' && sname[name_len] != '@')
continue;
if (ret >= 0) {
/* handle multiple matches */
if (last_bind != STB_WEAK && curr_bind != STB_WEAK) {
/* Only accept one non-weak bind. */
pr_warn("elf: ambiguous match for '%s', '%s' in '%s'\n",
sname, name, binary_path);
ret = -LIBBPF_ERRNO__FORMAT;
goto out;
} else if (curr_bind == STB_WEAK) {
/* already have a non-weak bind, and
* this is a weak bind, so ignore.
*/
continue;
}
}
/* Transform symbol's virtual address (absolute for
* binaries and relative for shared libs) into file
* offset, which is what kernel is expecting for
* uprobe/uretprobe attachment.
* See Documentation/trace/uprobetracer.rst for more
* details.
* This is done by looking up symbol's containing
* section's header and using it's virtual address
* (sh_addr) and corresponding file offset (sh_offset)
* to transform sym.st_value (virtual address) into
* desired final file offset.
*/
sym_scn = elf_getscn(elf, sym.st_shndx);
if (!sym_scn)
continue;
if (!gelf_getshdr(sym_scn, &sym_sh))
continue;
ret = sym.st_value - sym_sh.sh_addr + sym_sh.sh_offset;
last_bind = curr_bind;
}
if (ret > 0)
break;
}
if (ret > 0) {
pr_debug("elf: symbol address match for '%s' in '%s': 0x%lx\n", name, binary_path,
ret);
} else {
if (ret == 0) {
pr_warn("elf: '%s' is 0 in symtab for '%s': %s\n", name, binary_path,
is_shared_lib ? "should not be 0 in a shared library" :
"try using shared library path instead");
ret = -ENOENT;
} else {
pr_warn("elf: failed to find symbol '%s' in '%s'\n", name, binary_path);
}
}
out:
elf_end(elf);
close(fd);
return ret;
}
static const char *arch_specific_lib_paths(void)
{
/*
* Based on https://packages.debian.org/sid/libc6.
*
* Assume that the traced program is built for the same architecture
* as libbpf, which should cover the vast majority of cases.
*/
#if defined(__x86_64__)
return "/lib/x86_64-linux-gnu";
#elif defined(__i386__)
return "/lib/i386-linux-gnu";
#elif defined(__s390x__)
return "/lib/s390x-linux-gnu";
#elif defined(__s390__)
return "/lib/s390-linux-gnu";
#elif defined(__arm__) && defined(__SOFTFP__)
return "/lib/arm-linux-gnueabi";
#elif defined(__arm__) && !defined(__SOFTFP__)
return "/lib/arm-linux-gnueabihf";
#elif defined(__aarch64__)
return "/lib/aarch64-linux-gnu";
#elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 64
return "/lib/mips64el-linux-gnuabi64";
#elif defined(__mips__) && defined(__MIPSEL__) && _MIPS_SZLONG == 32
return "/lib/mipsel-linux-gnu";
#elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return "/lib/powerpc64le-linux-gnu";
#elif defined(__sparc__) && defined(__arch64__)
return "/lib/sparc64-linux-gnu";
#elif defined(__riscv) && __riscv_xlen == 64
return "/lib/riscv64-linux-gnu";
#else
return NULL;
#endif
}
/* Get full path to program/shared library. */
static int resolve_full_path(const char *file, char *result, size_t result_sz)
{
const char *search_paths[3] = {};
int i, perm;
if (str_has_sfx(file, ".so") || strstr(file, ".so.")) {
search_paths[0] = getenv("LD_LIBRARY_PATH");
search_paths[1] = "/usr/lib64:/usr/lib";
search_paths[2] = arch_specific_lib_paths();
perm = R_OK;
} else {
search_paths[0] = getenv("PATH");
search_paths[1] = "/usr/bin:/usr/sbin";
perm = R_OK | X_OK;
}
for (i = 0; i < ARRAY_SIZE(search_paths); i++) {
const char *s;
if (!search_paths[i])
continue;
for (s = search_paths[i]; s != NULL; s = strchr(s, ':')) {
char *next_path;
int seg_len;
if (s[0] == ':')
s++;
next_path = strchr(s, ':');
seg_len = next_path ? next_path - s : strlen(s);
if (!seg_len)
continue;
snprintf(result, result_sz, "%.*s/%s", seg_len, s, file);
/* ensure it has required permissions */
if (faccessat(AT_FDCWD, result, perm, AT_EACCESS) < 0)
continue;
pr_debug("resolved '%s' to '%s'\n", file, result);
return 0;
}
}
return -ENOENT;
}
LIBBPF_API struct bpf_link *
bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
const char *binary_path, size_t func_offset,
const struct bpf_uprobe_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE], *legacy_probe = NULL;
char full_binary_path[PATH_MAX];
struct bpf_link *link;
size_t ref_ctr_off;
int pfd, err;
bool retprobe, legacy;
const char *func_name;
if (!OPTS_VALID(opts, bpf_uprobe_opts))
return libbpf_err_ptr(-EINVAL);
retprobe = OPTS_GET(opts, retprobe, false);
ref_ctr_off = OPTS_GET(opts, ref_ctr_offset, 0);
pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
if (!binary_path)
return libbpf_err_ptr(-EINVAL);
if (!strchr(binary_path, '/')) {
err = resolve_full_path(binary_path, full_binary_path,
sizeof(full_binary_path));
if (err) {
pr_warn("prog '%s': failed to resolve full path for '%s': %d\n",
prog->name, binary_path, err);
return libbpf_err_ptr(err);
}
binary_path = full_binary_path;
}
func_name = OPTS_GET(opts, func_name, NULL);
if (func_name) {
long sym_off;
sym_off = elf_find_func_offset(binary_path, func_name);
if (sym_off < 0)
return libbpf_err_ptr(sym_off);
func_offset += sym_off;
}
legacy = determine_uprobe_perf_type() < 0;
if (!legacy) {
pfd = perf_event_open_probe(true /* uprobe */, retprobe, binary_path,
func_offset, pid, ref_ctr_off);
} else {
char probe_name[PATH_MAX + 64];
if (ref_ctr_off)
return libbpf_err_ptr(-EINVAL);
gen_uprobe_legacy_event_name(probe_name, sizeof(probe_name),
binary_path, func_offset);
legacy_probe = strdup(probe_name);
if (!legacy_probe)
return libbpf_err_ptr(-ENOMEM);
pfd = perf_event_uprobe_open_legacy(legacy_probe, retprobe,
binary_path, func_offset, pid);
}
if (pfd < 0) {
err = -errno;
pr_warn("prog '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
prog->name, retprobe ? "uretprobe" : "uprobe",
binary_path, func_offset,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto err_out;
}
link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
pr_warn("prog '%s': failed to attach to %s '%s:0x%zx': %s\n",
prog->name, retprobe ? "uretprobe" : "uprobe",
binary_path, func_offset,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
goto err_clean_legacy;
}
if (legacy) {
struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
perf_link->legacy_probe_name = legacy_probe;
perf_link->legacy_is_kprobe = false;
perf_link->legacy_is_retprobe = retprobe;
}
return link;
err_clean_legacy:
if (legacy)
remove_uprobe_event_legacy(legacy_probe, retprobe);
err_out:
free(legacy_probe);
return libbpf_err_ptr(err);
}
/* Format of u[ret]probe section definition supporting auto-attach:
* u[ret]probe/binary:function[+offset]
*
* binary can be an absolute/relative path or a filename; the latter is resolved to a
* full binary path via bpf_program__attach_uprobe_opts.
*
* Specifying uprobe+ ensures we carry out strict matching; either "uprobe" must be
* specified (and auto-attach is not possible) or the above format is specified for
* auto-attach.
*/
static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts);
char *probe_type = NULL, *binary_path = NULL, *func_name = NULL;
int n, ret = -EINVAL;
long offset = 0;
*link = NULL;
n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%m[a-zA-Z0-9_.]+%li",
&probe_type, &binary_path, &func_name, &offset);
switch (n) {
case 1:
/* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */
ret = 0;
break;
case 2:
pr_warn("prog '%s': section '%s' missing ':function[+offset]' specification\n",
prog->name, prog->sec_name);
break;
case 3:
case 4:
opts.retprobe = strcmp(probe_type, "uretprobe") == 0 ||
strcmp(probe_type, "uretprobe.s") == 0;
if (opts.retprobe && offset != 0) {
pr_warn("prog '%s': uretprobes do not support offset specification\n",
prog->name);
break;
}
opts.func_name = func_name;
*link = bpf_program__attach_uprobe_opts(prog, -1, binary_path, offset, &opts);
ret = libbpf_get_error(*link);
break;
default:
pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
prog->sec_name);
break;
}
free(probe_type);
free(binary_path);
free(func_name);
return ret;
}
struct bpf_link *bpf_program__attach_uprobe(const struct bpf_program *prog,
bool retprobe, pid_t pid,
const char *binary_path,
size_t func_offset)
{
DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts, .retprobe = retprobe);
return bpf_program__attach_uprobe_opts(prog, pid, binary_path, func_offset, &opts);
}
struct bpf_link *bpf_program__attach_usdt(const struct bpf_program *prog,
pid_t pid, const char *binary_path,
const char *usdt_provider, const char *usdt_name,
const struct bpf_usdt_opts *opts)
{
char resolved_path[512];
struct bpf_object *obj = prog->obj;
struct bpf_link *link;
__u64 usdt_cookie;
int err;
if (!OPTS_VALID(opts, bpf_uprobe_opts))
return libbpf_err_ptr(-EINVAL);
if (bpf_program__fd(prog) < 0) {
pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
prog->name);
return libbpf_err_ptr(-EINVAL);
}
if (!binary_path)
return libbpf_err_ptr(-EINVAL);
if (!strchr(binary_path, '/')) {
err = resolve_full_path(binary_path, resolved_path, sizeof(resolved_path));
if (err) {
pr_warn("prog '%s': failed to resolve full path for '%s': %d\n",
prog->name, binary_path, err);
return libbpf_err_ptr(err);
}
binary_path = resolved_path;
}
/* USDT manager is instantiated lazily on first USDT attach. It will
* be destroyed together with BPF object in bpf_object__close().
*/
if (IS_ERR(obj->usdt_man))
return libbpf_ptr(obj->usdt_man);
if (!obj->usdt_man) {
obj->usdt_man = usdt_manager_new(obj);
if (IS_ERR(obj->usdt_man))
return libbpf_ptr(obj->usdt_man);
}
usdt_cookie = OPTS_GET(opts, usdt_cookie, 0);
link = usdt_manager_attach_usdt(obj->usdt_man, prog, pid, binary_path,
usdt_provider, usdt_name, usdt_cookie);
err = libbpf_get_error(link);
if (err)
return libbpf_err_ptr(err);
return link;
}
static int attach_usdt(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
char *path = NULL, *provider = NULL, *name = NULL;
const char *sec_name;
int n, err;
sec_name = bpf_program__section_name(prog);
if (strcmp(sec_name, "usdt") == 0) {
/* no auto-attach for just SEC("usdt") */
*link = NULL;
return 0;
}
n = sscanf(sec_name, "usdt/%m[^:]:%m[^:]:%m[^:]", &path, &provider, &name);
if (n != 3) {
pr_warn("invalid section '%s', expected SEC(\"usdt/<path>:<provider>:<name>\")\n",
sec_name);
err = -EINVAL;
} else {
*link = bpf_program__attach_usdt(prog, -1 /* any process */, path,
provider, name, NULL);
err = libbpf_get_error(*link);
}
free(path);
free(provider);
free(name);
return err;
}
static int determine_tracepoint_id(const char *tp_category,
const char *tp_name)
{
char file[PATH_MAX];
int ret;
ret = snprintf(file, sizeof(file), "%s/events/%s/%s/id",
tracefs_path(), tp_category, tp_name);
if (ret < 0)
return -errno;
if (ret >= sizeof(file)) {
pr_debug("tracepoint %s/%s path is too long\n",
tp_category, tp_name);
return -E2BIG;
}
return parse_uint_from_file(file, "%d\n");
}
static int perf_event_open_tracepoint(const char *tp_category,
const char *tp_name)
{
const size_t attr_sz = sizeof(struct perf_event_attr);
struct perf_event_attr attr;
char errmsg[STRERR_BUFSIZE];
int tp_id, pfd, err;
tp_id = determine_tracepoint_id(tp_category, tp_name);
if (tp_id < 0) {
pr_warn("failed to determine tracepoint '%s/%s' perf event ID: %s\n",
tp_category, tp_name,
libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg)));
return tp_id;
}
memset(&attr, 0, attr_sz);
attr.type = PERF_TYPE_TRACEPOINT;
attr.size = attr_sz;
attr.config = tp_id;
pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
-1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
if (pfd < 0) {
err = -errno;
pr_warn("tracepoint '%s/%s' perf_event_open() failed: %s\n",
tp_category, tp_name,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
return err;
}
return pfd;
}
struct bpf_link *bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
const char *tp_category,
const char *tp_name,
const struct bpf_tracepoint_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int pfd, err;
if (!OPTS_VALID(opts, bpf_tracepoint_opts))
return libbpf_err_ptr(-EINVAL);
pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
pfd = perf_event_open_tracepoint(tp_category, tp_name);
if (pfd < 0) {
pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
prog->name, tp_category, tp_name,
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
pr_warn("prog '%s': failed to attach to tracepoint '%s/%s': %s\n",
prog->name, tp_category, tp_name,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(err);
}
return link;
}
struct bpf_link *bpf_program__attach_tracepoint(const struct bpf_program *prog,
const char *tp_category,
const char *tp_name)
{
return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
}
static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
char *sec_name, *tp_cat, *tp_name;
*link = NULL;
/* no auto-attach for SEC("tp") or SEC("tracepoint") */
if (strcmp(prog->sec_name, "tp") == 0 || strcmp(prog->sec_name, "tracepoint") == 0)
return 0;
sec_name = strdup(prog->sec_name);
if (!sec_name)
return -ENOMEM;
/* extract "tp/<category>/<name>" or "tracepoint/<category>/<name>" */
if (str_has_pfx(prog->sec_name, "tp/"))
tp_cat = sec_name + sizeof("tp/") - 1;
else
tp_cat = sec_name + sizeof("tracepoint/") - 1;
tp_name = strchr(tp_cat, '/');
if (!tp_name) {
free(sec_name);
return -EINVAL;
}
*tp_name = '\0';
tp_name++;
*link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name);
free(sec_name);
return libbpf_get_error(*link);
}
struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
const char *tp_name)
{
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int prog_fd, pfd;
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
pr_warn("prog '%s': can't attach before loaded\n", prog->name);
return libbpf_err_ptr(-EINVAL);
}
link = calloc(1, sizeof(*link));
if (!link)
return libbpf_err_ptr(-ENOMEM);
link->detach = &bpf_link__detach_fd;
pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
if (pfd < 0) {
pfd = -errno;
free(link);
pr_warn("prog '%s': failed to attach to raw tracepoint '%s': %s\n",
prog->name, tp_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
link->fd = pfd;
return link;
}
static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
static const char *const prefixes[] = {
"raw_tp",
"raw_tracepoint",
"raw_tp.w",
"raw_tracepoint.w",
};
size_t i;
const char *tp_name = NULL;
*link = NULL;
for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
size_t pfx_len;
if (!str_has_pfx(prog->sec_name, prefixes[i]))
continue;
pfx_len = strlen(prefixes[i]);
/* no auto-attach case of, e.g., SEC("raw_tp") */
if (prog->sec_name[pfx_len] == '\0')
return 0;
if (prog->sec_name[pfx_len] != '/')
continue;
tp_name = prog->sec_name + pfx_len + 1;
break;
}
if (!tp_name) {
pr_warn("prog '%s': invalid section name '%s'\n",
prog->name, prog->sec_name);
return -EINVAL;
}
*link = bpf_program__attach_raw_tracepoint(prog, tp_name);
return libbpf_get_error(*link);
}
/* Common logic for all BPF program types that attach to a btf_id */
static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog,
const struct bpf_trace_opts *opts)
{
LIBBPF_OPTS(bpf_link_create_opts, link_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int prog_fd, pfd;
if (!OPTS_VALID(opts, bpf_trace_opts))
return libbpf_err_ptr(-EINVAL);
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
pr_warn("prog '%s': can't attach before loaded\n", prog->name);
return libbpf_err_ptr(-EINVAL);
}
link = calloc(1, sizeof(*link));
if (!link)
return libbpf_err_ptr(-ENOMEM);
link->detach = &bpf_link__detach_fd;
/* libbpf is smart enough to redirect to BPF_RAW_TRACEPOINT_OPEN on old kernels */
link_opts.tracing.cookie = OPTS_GET(opts, cookie, 0);
pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), &link_opts);
if (pfd < 0) {
pfd = -errno;
free(link);
pr_warn("prog '%s': failed to attach: %s\n",
prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
link->fd = pfd;
return link;
}
struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
{
return bpf_program__attach_btf_id(prog, NULL);
}
struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
const struct bpf_trace_opts *opts)
{
return bpf_program__attach_btf_id(prog, opts);
}
struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
{
return bpf_program__attach_btf_id(prog, NULL);
}
static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
*link = bpf_program__attach_trace(prog);
return libbpf_get_error(*link);
}
static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
*link = bpf_program__attach_lsm(prog);
return libbpf_get_error(*link);
}
static struct bpf_link *
bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id,
const char *target_name)
{
DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
.target_btf_id = btf_id);
enum bpf_attach_type attach_type;
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int prog_fd, link_fd;
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
pr_warn("prog '%s': can't attach before loaded\n", prog->name);
return libbpf_err_ptr(-EINVAL);
}
link = calloc(1, sizeof(*link));
if (!link)
return libbpf_err_ptr(-ENOMEM);
link->detach = &bpf_link__detach_fd;
attach_type = bpf_program__expected_attach_type(prog);
link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);
if (link_fd < 0) {
link_fd = -errno;
free(link);
pr_warn("prog '%s': failed to attach to %s: %s\n",
prog->name, target_name,
libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(link_fd);
}
link->fd = link_fd;
return link;
}
struct bpf_link *
bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd)
{
return bpf_program__attach_fd(prog, cgroup_fd, 0, "cgroup");
}
struct bpf_link *
bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd)
{
return bpf_program__attach_fd(prog, netns_fd, 0, "netns");
}
struct bpf_link *bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex)
{
/* target_fd/target_ifindex use the same field in LINK_CREATE */
return bpf_program__attach_fd(prog, ifindex, 0, "xdp");
}
struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog,
int target_fd,
const char *attach_func_name)
{
int btf_id;
if (!!target_fd != !!attach_func_name) {
pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n",
prog->name);
return libbpf_err_ptr(-EINVAL);
}
if (prog->type != BPF_PROG_TYPE_EXT) {
pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace",
prog->name);
return libbpf_err_ptr(-EINVAL);
}
if (target_fd) {
btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);
if (btf_id < 0)
return libbpf_err_ptr(btf_id);
return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");
} else {
/* no target, so use raw_tracepoint_open for compatibility
* with old kernels
*/
return bpf_program__attach_trace(prog);
}
}
struct bpf_link *
bpf_program__attach_iter(const struct bpf_program *prog,
const struct bpf_iter_attach_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int prog_fd, link_fd;
__u32 target_fd = 0;
if (!OPTS_VALID(opts, bpf_iter_attach_opts))
return libbpf_err_ptr(-EINVAL);
link_create_opts.iter_info = OPTS_GET(opts, link_info, (void *)0);
link_create_opts.iter_info_len = OPTS_GET(opts, link_info_len, 0);
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
pr_warn("prog '%s': can't attach before loaded\n", prog->name);
return libbpf_err_ptr(-EINVAL);
}
link = calloc(1, sizeof(*link));
if (!link)
return libbpf_err_ptr(-ENOMEM);
link->detach = &bpf_link__detach_fd;
link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER,
&link_create_opts);
if (link_fd < 0) {
link_fd = -errno;
free(link);
pr_warn("prog '%s': failed to attach to iterator: %s\n",
prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(link_fd);
}
link->fd = link_fd;
return link;
}
static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
*link = bpf_program__attach_iter(prog, NULL);
return libbpf_get_error(*link);
}
struct bpf_link *bpf_program__attach(const struct bpf_program *prog)
{
struct bpf_link *link = NULL;
int err;
if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
return libbpf_err_ptr(-EOPNOTSUPP);
err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, &link);
if (err)
return libbpf_err_ptr(err);
/* When calling bpf_program__attach() explicitly, auto-attach support
* is expected to work, so NULL returned link is considered an error.
* This is different for skeleton's attach, see comment in
* bpf_object__attach_skeleton().
*/
if (!link)
return libbpf_err_ptr(-EOPNOTSUPP);
return link;
}
static int bpf_link__detach_struct_ops(struct bpf_link *link)
{
__u32 zero = 0;
if (bpf_map_delete_elem(link->fd, &zero))
return -errno;
return 0;
}
struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map)
{
struct bpf_struct_ops *st_ops;
struct bpf_link *link;
__u32 i, zero = 0;
int err;
if (!bpf_map__is_struct_ops(map) || map->fd == -1)
return libbpf_err_ptr(-EINVAL);
link = calloc(1, sizeof(*link));
if (!link)
return libbpf_err_ptr(-EINVAL);
st_ops = map->st_ops;
for (i = 0; i < btf_vlen(st_ops->type); i++) {
struct bpf_program *prog = st_ops->progs[i];
void *kern_data;
int prog_fd;
if (!prog)
continue;
prog_fd = bpf_program__fd(prog);
kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i];
*(unsigned long *)kern_data = prog_fd;
}
err = bpf_map_update_elem(map->fd, &zero, st_ops->kern_vdata, 0);
if (err) {
err = -errno;
free(link);
return libbpf_err_ptr(err);
}
link->detach = bpf_link__detach_struct_ops;
link->fd = map->fd;
return link;
}
typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr,
void *private_data);
static enum bpf_perf_event_ret
perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
void **copy_mem, size_t *copy_size,
bpf_perf_event_print_t fn, void *private_data)
{
struct perf_event_mmap_page *header = mmap_mem;
__u64 data_head = ring_buffer_read_head(header);
__u64 data_tail = header->data_tail;
void *base = ((__u8 *)header) + page_size;
int ret = LIBBPF_PERF_EVENT_CONT;
struct perf_event_header *ehdr;
size_t ehdr_size;
while (data_head != data_tail) {
ehdr = base + (data_tail & (mmap_size - 1));
ehdr_size = ehdr->size;
if (((void *)ehdr) + ehdr_size > base + mmap_size) {
void *copy_start = ehdr;
size_t len_first = base + mmap_size - copy_start;
size_t len_secnd = ehdr_size - len_first;
if (*copy_size < ehdr_size) {
free(*copy_mem);
*copy_mem = malloc(ehdr_size);
if (!*copy_mem) {
*copy_size = 0;
ret = LIBBPF_PERF_EVENT_ERROR;
break;
}
*copy_size = ehdr_size;
}
memcpy(*copy_mem, copy_start, len_first);
memcpy(*copy_mem + len_first, base, len_secnd);
ehdr = *copy_mem;
}
ret = fn(ehdr, private_data);
data_tail += ehdr_size;
if (ret != LIBBPF_PERF_EVENT_CONT)
break;
}
ring_buffer_write_tail(header, data_tail);
return libbpf_err(ret);
}
struct perf_buffer;
struct perf_buffer_params {
struct perf_event_attr *attr;
/* if event_cb is specified, it takes precendence */
perf_buffer_event_fn event_cb;
/* sample_cb and lost_cb are higher-level common-case callbacks */
perf_buffer_sample_fn sample_cb;
perf_buffer_lost_fn lost_cb;
void *ctx;
int cpu_cnt;
int *cpus;
int *map_keys;
};
struct perf_cpu_buf {
struct perf_buffer *pb;
void *base; /* mmap()'ed memory */
void *buf; /* for reconstructing segmented data */
size_t buf_size;
int fd;
int cpu;
int map_key;
};
struct perf_buffer {
perf_buffer_event_fn event_cb;
perf_buffer_sample_fn sample_cb;
perf_buffer_lost_fn lost_cb;
void *ctx; /* passed into callbacks */
size_t page_size;
size_t mmap_size;
struct perf_cpu_buf **cpu_bufs;
struct epoll_event *events;
int cpu_cnt; /* number of allocated CPU buffers */
int epoll_fd; /* perf event FD */
int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */
};
static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
struct perf_cpu_buf *cpu_buf)
{
if (!cpu_buf)
return;
if (cpu_buf->base &&
munmap(cpu_buf->base, pb->mmap_size + pb->page_size))
pr_warn("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
if (cpu_buf->fd >= 0) {
ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
close(cpu_buf->fd);
}
free(cpu_buf->buf);
free(cpu_buf);
}
void perf_buffer__free(struct perf_buffer *pb)
{
int i;
if (IS_ERR_OR_NULL(pb))
return;
if (pb->cpu_bufs) {
for (i = 0; i < pb->cpu_cnt; i++) {
struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
if (!cpu_buf)
continue;
bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
perf_buffer__free_cpu_buf(pb, cpu_buf);
}
free(pb->cpu_bufs);
}
if (pb->epoll_fd >= 0)
close(pb->epoll_fd);
free(pb->events);
free(pb);
}
static struct perf_cpu_buf *
perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
int cpu, int map_key)
{
struct perf_cpu_buf *cpu_buf;
char msg[STRERR_BUFSIZE];
int err;
cpu_buf = calloc(1, sizeof(*cpu_buf));
if (!cpu_buf)
return ERR_PTR(-ENOMEM);
cpu_buf->pb = pb;
cpu_buf->cpu = cpu;
cpu_buf->map_key = map_key;
cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu,
-1, PERF_FLAG_FD_CLOEXEC);
if (cpu_buf->fd < 0) {
err = -errno;
pr_warn("failed to open perf buffer event on cpu #%d: %s\n",
cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
goto error;
}
cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size,
PROT_READ | PROT_WRITE, MAP_SHARED,
cpu_buf->fd, 0);
if (cpu_buf->base == MAP_FAILED) {
cpu_buf->base = NULL;
err = -errno;
pr_warn("failed to mmap perf buffer on cpu #%d: %s\n",
cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
goto error;
}
if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
err = -errno;
pr_warn("failed to enable perf buffer event on cpu #%d: %s\n",
cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
goto error;
}
return cpu_buf;
error:
perf_buffer__free_cpu_buf(pb, cpu_buf);
return (struct perf_cpu_buf *)ERR_PTR(err);
}
static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
struct perf_buffer_params *p);
struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
perf_buffer_sample_fn sample_cb,
perf_buffer_lost_fn lost_cb,
void *ctx,
const struct perf_buffer_opts *opts)
{
const size_t attr_sz = sizeof(struct perf_event_attr);
struct perf_buffer_params p = {};
struct perf_event_attr attr;
__u32 sample_period;
if (!OPTS_VALID(opts, perf_buffer_opts))
return libbpf_err_ptr(-EINVAL);
sample_period = OPTS_GET(opts, sample_period, 1);
if (!sample_period)
sample_period = 1;
memset(&attr, 0, attr_sz);
attr.size = attr_sz;
attr.config = PERF_COUNT_SW_BPF_OUTPUT;
attr.type = PERF_TYPE_SOFTWARE;
attr.sample_type = PERF_SAMPLE_RAW;
attr.sample_period = sample_period;
attr.wakeup_events = sample_period;
p.attr = &attr;
p.sample_cb = sample_cb;
p.lost_cb = lost_cb;
p.ctx = ctx;
return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
}
struct perf_buffer *perf_buffer__new_raw(int map_fd, size_t page_cnt,
struct perf_event_attr *attr,
perf_buffer_event_fn event_cb, void *ctx,
const struct perf_buffer_raw_opts *opts)
{
struct perf_buffer_params p = {};
if (!attr)
return libbpf_err_ptr(-EINVAL);
if (!OPTS_VALID(opts, perf_buffer_raw_opts))
return libbpf_err_ptr(-EINVAL);
p.attr = attr;
p.event_cb = event_cb;
p.ctx = ctx;
p.cpu_cnt = OPTS_GET(opts, cpu_cnt, 0);
p.cpus = OPTS_GET(opts, cpus, NULL);
p.map_keys = OPTS_GET(opts, map_keys, NULL);
return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
}
static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
struct perf_buffer_params *p)
{
const char *online_cpus_file = "/sys/devices/system/cpu/online";
struct bpf_map_info map;
char msg[STRERR_BUFSIZE];
struct perf_buffer *pb;
bool *online = NULL;
__u32 map_info_len;
int err, i, j, n;
if (page_cnt == 0 || (page_cnt & (page_cnt - 1))) {
pr_warn("page count should be power of two, but is %zu\n",
page_cnt);
return ERR_PTR(-EINVAL);
}
/* best-effort sanity checks */
memset(&map, 0, sizeof(map));
map_info_len = sizeof(map);
err = bpf_map_get_info_by_fd(map_fd, &map, &map_info_len);
if (err) {
err = -errno;
/* if BPF_OBJ_GET_INFO_BY_FD is supported, will return
* -EBADFD, -EFAULT, or -E2BIG on real error
*/
if (err != -EINVAL) {
pr_warn("failed to get map info for map FD %d: %s\n",
map_fd, libbpf_strerror_r(err, msg, sizeof(msg)));
return ERR_PTR(err);
}
pr_debug("failed to get map info for FD %d; API not supported? Ignoring...\n",
map_fd);
} else {
if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
pr_warn("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
map.name);
return ERR_PTR(-EINVAL);
}
}
pb = calloc(1, sizeof(*pb));
if (!pb)
return ERR_PTR(-ENOMEM);
pb->event_cb = p->event_cb;
pb->sample_cb = p->sample_cb;
pb->lost_cb = p->lost_cb;
pb->ctx = p->ctx;
pb->page_size = getpagesize();
pb->mmap_size = pb->page_size * page_cnt;
pb->map_fd = map_fd;
pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
if (pb->epoll_fd < 0) {
err = -errno;
pr_warn("failed to create epoll instance: %s\n",
libbpf_strerror_r(err, msg, sizeof(msg)));
goto error;
}
if (p->cpu_cnt > 0) {
pb->cpu_cnt = p->cpu_cnt;
} else {
pb->cpu_cnt = libbpf_num_possible_cpus();
if (pb->cpu_cnt < 0) {
err = pb->cpu_cnt;
goto error;
}
if (map.max_entries && map.max_entries < pb->cpu_cnt)
pb->cpu_cnt = map.max_entries;
}
pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
if (!pb->events) {
err = -ENOMEM;
pr_warn("failed to allocate events: out of memory\n");
goto error;
}
pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs));
if (!pb->cpu_bufs) {
err = -ENOMEM;
pr_warn("failed to allocate buffers: out of memory\n");
goto error;
}
err = parse_cpu_mask_file(online_cpus_file, &online, &n);
if (err) {
pr_warn("failed to get online CPU mask: %d\n", err);
goto error;
}
for (i = 0, j = 0; i < pb->cpu_cnt; i++) {
struct perf_cpu_buf *cpu_buf;
int cpu, map_key;
cpu = p->cpu_cnt > 0 ? p->cpus[i] : i;
map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i;
/* in case user didn't explicitly requested particular CPUs to
* be attached to, skip offline/not present CPUs
*/
if (p->cpu_cnt <= 0 && (cpu >= n || !online[cpu]))
continue;
cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key);
if (IS_ERR(cpu_buf)) {
err = PTR_ERR(cpu_buf);
goto error;
}
pb->cpu_bufs[j] = cpu_buf;
err = bpf_map_update_elem(pb->map_fd, &map_key,
&cpu_buf->fd, 0);
if (err) {
err = -errno;
pr_warn("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
cpu, map_key, cpu_buf->fd,
libbpf_strerror_r(err, msg, sizeof(msg)));
goto error;
}
pb->events[j].events = EPOLLIN;
pb->events[j].data.ptr = cpu_buf;
if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
&pb->events[j]) < 0) {
err = -errno;
pr_warn("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
cpu, cpu_buf->fd,
libbpf_strerror_r(err, msg, sizeof(msg)));
goto error;
}
j++;
}
pb->cpu_cnt = j;
free(online);
return pb;
error:
free(online);
if (pb)
perf_buffer__free(pb);
return ERR_PTR(err);
}
struct perf_sample_raw {
struct perf_event_header header;
uint32_t size;
char data[];
};
struct perf_sample_lost {
struct perf_event_header header;
uint64_t id;
uint64_t lost;
uint64_t sample_id;
};
static enum bpf_perf_event_ret
perf_buffer__process_record(struct perf_event_header *e, void *ctx)
{
struct perf_cpu_buf *cpu_buf = ctx;
struct perf_buffer *pb = cpu_buf->pb;
void *data = e;
/* user wants full control over parsing perf event */
if (pb->event_cb)
return pb->event_cb(pb->ctx, cpu_buf->cpu, e);
switch (e->type) {
case PERF_RECORD_SAMPLE: {
struct perf_sample_raw *s = data;
if (pb->sample_cb)
pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size);
break;
}
case PERF_RECORD_LOST: {
struct perf_sample_lost *s = data;
if (pb->lost_cb)
pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost);
break;
}
default:
pr_warn("unknown perf sample type %d\n", e->type);
return LIBBPF_PERF_EVENT_ERROR;
}
return LIBBPF_PERF_EVENT_CONT;
}
static int perf_buffer__process_records(struct perf_buffer *pb,
struct perf_cpu_buf *cpu_buf)
{
enum bpf_perf_event_ret ret;
ret = perf_event_read_simple(cpu_buf->base, pb->mmap_size,
pb->page_size, &cpu_buf->buf,
&cpu_buf->buf_size,
perf_buffer__process_record, cpu_buf);
if (ret != LIBBPF_PERF_EVENT_CONT)
return ret;
return 0;
}
int perf_buffer__epoll_fd(const struct perf_buffer *pb)
{
return pb->epoll_fd;
}
int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
{
int i, cnt, err;
cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
if (cnt < 0)
return -errno;
for (i = 0; i < cnt; i++) {
struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
err = perf_buffer__process_records(pb, cpu_buf);
if (err) {
pr_warn("error while processing records: %d\n", err);
return libbpf_err(err);
}
}
return cnt;
}
/* Return number of PERF_EVENT_ARRAY map slots set up by this perf_buffer
* manager.
*/
size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb)
{
return pb->cpu_cnt;
}
/*
* Return perf_event FD of a ring buffer in *buf_idx* slot of
* PERF_EVENT_ARRAY BPF map. This FD can be polled for new data using
* select()/poll()/epoll() Linux syscalls.
*/
int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx)
{
struct perf_cpu_buf *cpu_buf;
if (buf_idx >= pb->cpu_cnt)
return libbpf_err(-EINVAL);
cpu_buf = pb->cpu_bufs[buf_idx];
if (!cpu_buf)
return libbpf_err(-ENOENT);
return cpu_buf->fd;
}
int perf_buffer__buffer(struct perf_buffer *pb, int buf_idx, void **buf, size_t *buf_size)
{
struct perf_cpu_buf *cpu_buf;
if (buf_idx >= pb->cpu_cnt)
return libbpf_err(-EINVAL);
cpu_buf = pb->cpu_bufs[buf_idx];
if (!cpu_buf)
return libbpf_err(-ENOENT);
*buf = cpu_buf->base;
*buf_size = pb->mmap_size;
return 0;
}
/*
* Consume data from perf ring buffer corresponding to slot *buf_idx* in
* PERF_EVENT_ARRAY BPF map without waiting/polling. If there is no data to
* consume, do nothing and return success.
* Returns:
* - 0 on success;
* - <0 on failure.
*/
int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx)
{
struct perf_cpu_buf *cpu_buf;
if (buf_idx >= pb->cpu_cnt)
return libbpf_err(-EINVAL);
cpu_buf = pb->cpu_bufs[buf_idx];
if (!cpu_buf)
return libbpf_err(-ENOENT);
return perf_buffer__process_records(pb, cpu_buf);
}
int perf_buffer__consume(struct perf_buffer *pb)
{
int i, err;
for (i = 0; i < pb->cpu_cnt; i++) {
struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
if (!cpu_buf)
continue;
err = perf_buffer__process_records(pb, cpu_buf);
if (err) {
pr_warn("perf_buffer: failed to process records in buffer #%d: %d\n", i, err);
return libbpf_err(err);
}
}
return 0;
}
int bpf_program__set_attach_target(struct bpf_program *prog,
int attach_prog_fd,
const char *attach_func_name)
{
int btf_obj_fd = 0, btf_id = 0, err;
if (!prog || attach_prog_fd < 0)
return libbpf_err(-EINVAL);
if (prog->obj->loaded)
return libbpf_err(-EINVAL);
if (attach_prog_fd && !attach_func_name) {
/* remember attach_prog_fd and let bpf_program__load() find
* BTF ID during the program load
*/
prog->attach_prog_fd = attach_prog_fd;
return 0;
}
if (attach_prog_fd) {
btf_id = libbpf_find_prog_btf_id(attach_func_name,
attach_prog_fd);
if (btf_id < 0)
return libbpf_err(btf_id);
} else {
if (!attach_func_name)
return libbpf_err(-EINVAL);
/* load btf_vmlinux, if not yet */
err = bpf_object__load_vmlinux_btf(prog->obj, true);
if (err)
return libbpf_err(err);
err = find_kernel_btf_id(prog->obj, attach_func_name,
prog->expected_attach_type,
&btf_obj_fd, &btf_id);
if (err)
return libbpf_err(err);
}
prog->attach_btf_id = btf_id;
prog->attach_btf_obj_fd = btf_obj_fd;
prog->attach_prog_fd = attach_prog_fd;
return 0;
}
int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz)
{
int err = 0, n, len, start, end = -1;
bool *tmp;
*mask = NULL;
*mask_sz = 0;
/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
while (*s) {
if (*s == ',' || *s == '\n') {
s++;
continue;
}
n = sscanf(s, "%d%n-%d%n", &start, &len, &end, &len);
if (n <= 0 || n > 2) {
pr_warn("Failed to get CPU range %s: %d\n", s, n);
err = -EINVAL;
goto cleanup;
} else if (n == 1) {
end = start;
}
if (start < 0 || start > end) {
pr_warn("Invalid CPU range [%d,%d] in %s\n",
start, end, s);
err = -EINVAL;
goto cleanup;
}
tmp = realloc(*mask, end + 1);
if (!tmp) {
err = -ENOMEM;
goto cleanup;
}
*mask = tmp;
memset(tmp + *mask_sz, 0, start - *mask_sz);
memset(tmp + start, 1, end - start + 1);
*mask_sz = end + 1;
s += len;
}
if (!*mask_sz) {
pr_warn("Empty CPU range\n");
return -EINVAL;
}
return 0;
cleanup:
free(*mask);
*mask = NULL;
return err;
}
int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz)
{
int fd, err = 0, len;
char buf[128];
fd = open(fcpu, O_RDONLY | O_CLOEXEC);
if (fd < 0) {
err = -errno;
pr_warn("Failed to open cpu mask file %s: %d\n", fcpu, err);
return err;
}
len = read(fd, buf, sizeof(buf));
close(fd);
if (len <= 0) {
err = len ? -errno : -EINVAL;
pr_warn("Failed to read cpu mask from %s: %d\n", fcpu, err);
return err;
}
if (len >= sizeof(buf)) {
pr_warn("CPU mask is too big in file %s\n", fcpu);
return -E2BIG;
}
buf[len] = '\0';
return parse_cpu_mask_str(buf, mask, mask_sz);
}
int libbpf_num_possible_cpus(void)
{
static const char *fcpu = "/sys/devices/system/cpu/possible";
static int cpus;
int err, n, i, tmp_cpus;
bool *mask;
tmp_cpus = READ_ONCE(cpus);
if (tmp_cpus > 0)
return tmp_cpus;
err = parse_cpu_mask_file(fcpu, &mask, &n);
if (err)
return libbpf_err(err);
tmp_cpus = 0;
for (i = 0; i < n; i++) {
if (mask[i])
tmp_cpus++;
}
free(mask);
WRITE_ONCE(cpus, tmp_cpus);
return tmp_cpus;
}
static int populate_skeleton_maps(const struct bpf_object *obj,
struct bpf_map_skeleton *maps,
size_t map_cnt)
{
int i;
for (i = 0; i < map_cnt; i++) {
struct bpf_map **map = maps[i].map;
const char *name = maps[i].name;
void **mmaped = maps[i].mmaped;
*map = bpf_object__find_map_by_name(obj, name);
if (!*map) {
pr_warn("failed to find skeleton map '%s'\n", name);
return -ESRCH;
}
/* externs shouldn't be pre-setup from user code */
if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG)
*mmaped = (*map)->mmaped;
}
return 0;
}
static int populate_skeleton_progs(const struct bpf_object *obj,
struct bpf_prog_skeleton *progs,
size_t prog_cnt)
{
int i;
for (i = 0; i < prog_cnt; i++) {
struct bpf_program **prog = progs[i].prog;
const char *name = progs[i].name;
*prog = bpf_object__find_program_by_name(obj, name);
if (!*prog) {
pr_warn("failed to find skeleton program '%s'\n", name);
return -ESRCH;
}
}
return 0;
}
int bpf_object__open_skeleton(struct bpf_object_skeleton *s,
const struct bpf_object_open_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_object_open_opts, skel_opts,
.object_name = s->name,
);
struct bpf_object *obj;
int err;
/* Attempt to preserve opts->object_name, unless overriden by user
* explicitly. Overwriting object name for skeletons is discouraged,
* as it breaks global data maps, because they contain object name
* prefix as their own map name prefix. When skeleton is generated,
* bpftool is making an assumption that this name will stay the same.
*/
if (opts) {
memcpy(&skel_opts, opts, sizeof(*opts));
if (!opts->object_name)
skel_opts.object_name = s->name;
}
obj = bpf_object__open_mem(s->data, s->data_sz, &skel_opts);
err = libbpf_get_error(obj);
if (err) {
pr_warn("failed to initialize skeleton BPF object '%s': %d\n",
s->name, err);
return libbpf_err(err);
}
*s->obj = obj;
err = populate_skeleton_maps(obj, s->maps, s->map_cnt);
if (err) {
pr_warn("failed to populate skeleton maps for '%s': %d\n", s->name, err);
return libbpf_err(err);
}
err = populate_skeleton_progs(obj, s->progs, s->prog_cnt);
if (err) {
pr_warn("failed to populate skeleton progs for '%s': %d\n", s->name, err);
return libbpf_err(err);
}
return 0;
}
int bpf_object__open_subskeleton(struct bpf_object_subskeleton *s)
{
int err, len, var_idx, i;
const char *var_name;
const struct bpf_map *map;
struct btf *btf;
__u32 map_type_id;
const struct btf_type *map_type, *var_type;
const struct bpf_var_skeleton *var_skel;
struct btf_var_secinfo *var;
if (!s->obj)
return libbpf_err(-EINVAL);
btf = bpf_object__btf(s->obj);
if (!btf) {
pr_warn("subskeletons require BTF at runtime (object %s)\n",
bpf_object__name(s->obj));
return libbpf_err(-errno);
}
err = populate_skeleton_maps(s->obj, s->maps, s->map_cnt);
if (err) {
pr_warn("failed to populate subskeleton maps: %d\n", err);
return libbpf_err(err);
}
err = populate_skeleton_progs(s->obj, s->progs, s->prog_cnt);
if (err) {
pr_warn("failed to populate subskeleton maps: %d\n", err);
return libbpf_err(err);
}
for (var_idx = 0; var_idx < s->var_cnt; var_idx++) {
var_skel = &s->vars[var_idx];
map = *var_skel->map;
map_type_id = bpf_map__btf_value_type_id(map);
map_type = btf__type_by_id(btf, map_type_id);
if (!btf_is_datasec(map_type)) {
pr_warn("type for map '%1$s' is not a datasec: %2$s",
bpf_map__name(map),
__btf_kind_str(btf_kind(map_type)));
return libbpf_err(-EINVAL);
}
len = btf_vlen(map_type);
var = btf_var_secinfos(map_type);
for (i = 0; i < len; i++, var++) {
var_type = btf__type_by_id(btf, var->type);
var_name = btf__name_by_offset(btf, var_type->name_off);
if (strcmp(var_name, var_skel->name) == 0) {
*var_skel->addr = map->mmaped + var->offset;
break;
}
}
}
return 0;
}
void bpf_object__destroy_subskeleton(struct bpf_object_subskeleton *s)
{
if (!s)
return;
free(s->maps);
free(s->progs);
free(s->vars);
free(s);
}
int bpf_object__load_skeleton(struct bpf_object_skeleton *s)
{
int i, err;
err = bpf_object__load(*s->obj);
if (err) {
pr_warn("failed to load BPF skeleton '%s': %d\n", s->name, err);
return libbpf_err(err);
}
for (i = 0; i < s->map_cnt; i++) {
struct bpf_map *map = *s->maps[i].map;
size_t mmap_sz = bpf_map_mmap_sz(map);
int prot, map_fd = bpf_map__fd(map);
void **mmaped = s->maps[i].mmaped;
if (!mmaped)
continue;
if (!(map->def.map_flags & BPF_F_MMAPABLE)) {
*mmaped = NULL;
continue;
}
if (map->def.map_flags & BPF_F_RDONLY_PROG)
prot = PROT_READ;
else
prot = PROT_READ | PROT_WRITE;
/* Remap anonymous mmap()-ed "map initialization image" as
* a BPF map-backed mmap()-ed memory, but preserving the same
* memory address. This will cause kernel to change process'
* page table to point to a different piece of kernel memory,
* but from userspace point of view memory address (and its
* contents, being identical at this point) will stay the
* same. This mapping will be released by bpf_object__close()
* as per normal clean up procedure, so we don't need to worry
* about it from skeleton's clean up perspective.
*/
*mmaped = mmap(map->mmaped, mmap_sz, prot,
MAP_SHARED | MAP_FIXED, map_fd, 0);
if (*mmaped == MAP_FAILED) {
err = -errno;
*mmaped = NULL;
pr_warn("failed to re-mmap() map '%s': %d\n",
bpf_map__name(map), err);
return libbpf_err(err);
}
}
return 0;
}
int bpf_object__attach_skeleton(struct bpf_object_skeleton *s)
{
int i, err;
for (i = 0; i < s->prog_cnt; i++) {
struct bpf_program *prog = *s->progs[i].prog;
struct bpf_link **link = s->progs[i].link;
if (!prog->autoload || !prog->autoattach)
continue;
/* auto-attaching not supported for this program */
if (!prog->sec_def || !prog->sec_def->prog_attach_fn)
continue;
/* if user already set the link manually, don't attempt auto-attach */
if (*link)
continue;
err = prog->sec_def->prog_attach_fn(prog, prog->sec_def->cookie, link);
if (err) {
pr_warn("prog '%s': failed to auto-attach: %d\n",
bpf_program__name(prog), err);
return libbpf_err(err);
}
/* It's possible that for some SEC() definitions auto-attach
* is supported in some cases (e.g., if definition completely
* specifies target information), but is not in other cases.
* SEC("uprobe") is one such case. If user specified target
* binary and function name, such BPF program can be
* auto-attached. But if not, it shouldn't trigger skeleton's
* attach to fail. It should just be skipped.
* attach_fn signals such case with returning 0 (no error) and
* setting link to NULL.
*/
}
return 0;
}
void bpf_object__detach_skeleton(struct bpf_object_skeleton *s)
{
int i;
for (i = 0; i < s->prog_cnt; i++) {
struct bpf_link **link = s->progs[i].link;
bpf_link__destroy(*link);
*link = NULL;
}
}
void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s)
{
if (!s)
return;
if (s->progs)
bpf_object__detach_skeleton(s);
if (s->obj)
bpf_object__close(*s->obj);
free(s->maps);
free(s->progs);
free(s);
}
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