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linux-zen-server/tools/perf/util/symbol-elf.c

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Initial commit
2023-08-30 17:53:23 +02:00
// SPDX-License-Identifier: GPL-2.0
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>
#include "dso.h"
#include "map.h"
#include "maps.h"
#include "symbol.h"
#include "symsrc.h"
#include "demangle-ocaml.h"
#include "demangle-java.h"
#include "demangle-rust.h"
#include "machine.h"
#include "vdso.h"
#include "debug.h"
#include "util/copyfile.h"
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/zalloc.h>
#include <symbol/kallsyms.h>
#include <internal/lib.h>
#ifndef EM_AARCH64
#define EM_AARCH64 183 /* ARM 64 bit */
#endif
#ifndef ELF32_ST_VISIBILITY
#define ELF32_ST_VISIBILITY(o) ((o) & 0x03)
#endif
/* For ELF64 the definitions are the same. */
#ifndef ELF64_ST_VISIBILITY
#define ELF64_ST_VISIBILITY(o) ELF32_ST_VISIBILITY (o)
#endif
/* How to extract information held in the st_other field. */
#ifndef GELF_ST_VISIBILITY
#define GELF_ST_VISIBILITY(val) ELF64_ST_VISIBILITY (val)
#endif
typedef Elf64_Nhdr GElf_Nhdr;
#ifndef DMGL_PARAMS
#define DMGL_NO_OPTS 0 /* For readability... */
#define DMGL_PARAMS (1 << 0) /* Include function args */
#define DMGL_ANSI (1 << 1) /* Include const, volatile, etc */
#endif
#ifdef HAVE_LIBBFD_SUPPORT
#define PACKAGE 'perf'
#include <bfd.h>
#else
#ifdef HAVE_CPLUS_DEMANGLE_SUPPORT
extern char *cplus_demangle(const char *, int);
static inline char *bfd_demangle(void __maybe_unused *v, const char *c, int i)
{
return cplus_demangle(c, i);
}
#else
#ifdef NO_DEMANGLE
static inline char *bfd_demangle(void __maybe_unused *v,
const char __maybe_unused *c,
int __maybe_unused i)
{
return NULL;
}
#endif
#endif
#endif
#ifndef HAVE_ELF_GETPHDRNUM_SUPPORT
static int elf_getphdrnum(Elf *elf, size_t *dst)
{
GElf_Ehdr gehdr;
GElf_Ehdr *ehdr;
ehdr = gelf_getehdr(elf, &gehdr);
if (!ehdr)
return -1;
*dst = ehdr->e_phnum;
return 0;
}
#endif
#ifndef HAVE_ELF_GETSHDRSTRNDX_SUPPORT
static int elf_getshdrstrndx(Elf *elf __maybe_unused, size_t *dst __maybe_unused)
{
pr_err("%s: update your libelf to > 0.140, this one lacks elf_getshdrstrndx().\n", __func__);
return -1;
}
#endif
#ifndef NT_GNU_BUILD_ID
#define NT_GNU_BUILD_ID 3
#endif
/**
* elf_symtab__for_each_symbol - iterate thru all the symbols
*
* @syms: struct elf_symtab instance to iterate
* @idx: uint32_t idx
* @sym: GElf_Sym iterator
*/
#define elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) \
for (idx = 0, gelf_getsym(syms, idx, &sym);\
idx < nr_syms; \
idx++, gelf_getsym(syms, idx, &sym))
static inline uint8_t elf_sym__type(const GElf_Sym *sym)
{
return GELF_ST_TYPE(sym->st_info);
}
static inline uint8_t elf_sym__visibility(const GElf_Sym *sym)
{
return GELF_ST_VISIBILITY(sym->st_other);
}
#ifndef STT_GNU_IFUNC
#define STT_GNU_IFUNC 10
#endif
static inline int elf_sym__is_function(const GElf_Sym *sym)
{
return (elf_sym__type(sym) == STT_FUNC ||
elf_sym__type(sym) == STT_GNU_IFUNC) &&
sym->st_name != 0 &&
sym->st_shndx != SHN_UNDEF;
}
static inline bool elf_sym__is_object(const GElf_Sym *sym)
{
return elf_sym__type(sym) == STT_OBJECT &&
sym->st_name != 0 &&
sym->st_shndx != SHN_UNDEF;
}
static inline int elf_sym__is_label(const GElf_Sym *sym)
{
return elf_sym__type(sym) == STT_NOTYPE &&
sym->st_name != 0 &&
sym->st_shndx != SHN_UNDEF &&
sym->st_shndx != SHN_ABS &&
elf_sym__visibility(sym) != STV_HIDDEN &&
elf_sym__visibility(sym) != STV_INTERNAL;
}
static bool elf_sym__filter(GElf_Sym *sym)
{
return elf_sym__is_function(sym) || elf_sym__is_object(sym);
}
static inline const char *elf_sym__name(const GElf_Sym *sym,
const Elf_Data *symstrs)
{
return symstrs->d_buf + sym->st_name;
}
static inline const char *elf_sec__name(const GElf_Shdr *shdr,
const Elf_Data *secstrs)
{
return secstrs->d_buf + shdr->sh_name;
}
static inline int elf_sec__is_text(const GElf_Shdr *shdr,
const Elf_Data *secstrs)
{
return strstr(elf_sec__name(shdr, secstrs), "text") != NULL;
}
static inline bool elf_sec__is_data(const GElf_Shdr *shdr,
const Elf_Data *secstrs)
{
return strstr(elf_sec__name(shdr, secstrs), "data") != NULL;
}
static bool elf_sec__filter(GElf_Shdr *shdr, Elf_Data *secstrs)
{
return elf_sec__is_text(shdr, secstrs) ||
elf_sec__is_data(shdr, secstrs);
}
static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
{
Elf_Scn *sec = NULL;
GElf_Shdr shdr;
size_t cnt = 1;
while ((sec = elf_nextscn(elf, sec)) != NULL) {
gelf_getshdr(sec, &shdr);
if ((addr >= shdr.sh_addr) &&
(addr < (shdr.sh_addr + shdr.sh_size)))
return cnt;
++cnt;
}
return -1;
}
Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
GElf_Shdr *shp, const char *name, size_t *idx)
{
Elf_Scn *sec = NULL;
size_t cnt = 1;
/* Elf is corrupted/truncated, avoid calling elf_strptr. */
if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL))
return NULL;
while ((sec = elf_nextscn(elf, sec)) != NULL) {
char *str;
gelf_getshdr(sec, shp);
str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
if (str && !strcmp(name, str)) {
if (idx)
*idx = cnt;
return sec;
}
++cnt;
}
return NULL;
}
bool filename__has_section(const char *filename, const char *sec)
{
int fd;
Elf *elf;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
bool found = false;
fd = open(filename, O_RDONLY);
if (fd < 0)
return false;
elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
if (elf == NULL)
goto out;
if (gelf_getehdr(elf, &ehdr) == NULL)
goto elf_out;
found = !!elf_section_by_name(elf, &ehdr, &shdr, sec, NULL);
elf_out:
elf_end(elf);
out:
close(fd);
return found;
}
static int elf_read_program_header(Elf *elf, u64 vaddr, GElf_Phdr *phdr)
{
size_t i, phdrnum;
u64 sz;
if (elf_getphdrnum(elf, &phdrnum))
return -1;
for (i = 0; i < phdrnum; i++) {
if (gelf_getphdr(elf, i, phdr) == NULL)
return -1;
if (phdr->p_type != PT_LOAD)
continue;
sz = max(phdr->p_memsz, phdr->p_filesz);
if (!sz)
continue;
if (vaddr >= phdr->p_vaddr && (vaddr < phdr->p_vaddr + sz))
return 0;
}
/* Not found any valid program header */
return -1;
}
static bool want_demangle(bool is_kernel_sym)
{
return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
}
static char *demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
{
int demangle_flags = verbose > 0 ? (DMGL_PARAMS | DMGL_ANSI) : DMGL_NO_OPTS;
char *demangled = NULL;
/*
* We need to figure out if the object was created from C++ sources
* DWARF DW_compile_unit has this, but we don't always have access
* to it...
*/
if (!want_demangle(dso->kernel || kmodule))
return demangled;
demangled = bfd_demangle(NULL, elf_name, demangle_flags);
if (demangled == NULL) {
demangled = ocaml_demangle_sym(elf_name);
if (demangled == NULL) {
demangled = java_demangle_sym(elf_name, JAVA_DEMANGLE_NORET);
}
}
else if (rust_is_mangled(demangled))
/*
* Input to Rust demangling is the BFD-demangled
* name which it Rust-demangles in place.
*/
rust_demangle_sym(demangled);
return demangled;
}
struct rel_info {
u32 nr_entries;
u32 *sorted;
bool is_rela;
Elf_Data *reldata;
GElf_Rela rela;
GElf_Rel rel;
};
static u32 get_rel_symidx(struct rel_info *ri, u32 idx)
{
idx = ri->sorted ? ri->sorted[idx] : idx;
if (ri->is_rela) {
gelf_getrela(ri->reldata, idx, &ri->rela);
return GELF_R_SYM(ri->rela.r_info);
}
gelf_getrel(ri->reldata, idx, &ri->rel);
return GELF_R_SYM(ri->rel.r_info);
}
static u64 get_rel_offset(struct rel_info *ri, u32 x)
{
if (ri->is_rela) {
GElf_Rela rela;
gelf_getrela(ri->reldata, x, &rela);
return rela.r_offset;
} else {
GElf_Rel rel;
gelf_getrel(ri->reldata, x, &rel);
return rel.r_offset;
}
}
static int rel_cmp(const void *a, const void *b, void *r)
{
struct rel_info *ri = r;
u64 a_offset = get_rel_offset(ri, *(const u32 *)a);
u64 b_offset = get_rel_offset(ri, *(const u32 *)b);
return a_offset < b_offset ? -1 : (a_offset > b_offset ? 1 : 0);
}
static int sort_rel(struct rel_info *ri)
{
size_t sz = sizeof(ri->sorted[0]);
u32 i;
ri->sorted = calloc(ri->nr_entries, sz);
if (!ri->sorted)
return -1;
for (i = 0; i < ri->nr_entries; i++)
ri->sorted[i] = i;
qsort_r(ri->sorted, ri->nr_entries, sz, rel_cmp, ri);
return 0;
}
/*
* For x86_64, the GNU linker is putting IFUNC information in the relocation
* addend.
*/
static bool addend_may_be_ifunc(GElf_Ehdr *ehdr, struct rel_info *ri)
{
return ehdr->e_machine == EM_X86_64 && ri->is_rela &&
GELF_R_TYPE(ri->rela.r_info) == R_X86_64_IRELATIVE;
}
static bool get_ifunc_name(Elf *elf, struct dso *dso, GElf_Ehdr *ehdr,
struct rel_info *ri, char *buf, size_t buf_sz)
{
u64 addr = ri->rela.r_addend;
struct symbol *sym;
GElf_Phdr phdr;
if (!addend_may_be_ifunc(ehdr, ri))
return false;
if (elf_read_program_header(elf, addr, &phdr))
return false;
addr -= phdr.p_vaddr - phdr.p_offset;
sym = dso__find_symbol_nocache(dso, addr);
/* Expecting the address to be an IFUNC or IFUNC alias */
if (!sym || sym->start != addr || (sym->type != STT_GNU_IFUNC && !sym->ifunc_alias))
return false;
snprintf(buf, buf_sz, "%s@plt", sym->name);
return true;
}
static void exit_rel(struct rel_info *ri)
{
free(ri->sorted);
}
static bool get_plt_sizes(struct dso *dso, GElf_Ehdr *ehdr, GElf_Shdr *shdr_plt,
u64 *plt_header_size, u64 *plt_entry_size)
{
switch (ehdr->e_machine) {
case EM_ARM:
*plt_header_size = 20;
*plt_entry_size = 12;
return true;
case EM_AARCH64:
*plt_header_size = 32;
*plt_entry_size = 16;
return true;
case EM_SPARC:
*plt_header_size = 48;
*plt_entry_size = 12;
return true;
case EM_SPARCV9:
*plt_header_size = 128;
*plt_entry_size = 32;
return true;
case EM_386:
case EM_X86_64:
*plt_entry_size = shdr_plt->sh_entsize;
/* Size is 8 or 16, if not, assume alignment indicates size */
if (*plt_entry_size != 8 && *plt_entry_size != 16)
*plt_entry_size = shdr_plt->sh_addralign == 8 ? 8 : 16;
*plt_header_size = *plt_entry_size;
break;
default: /* FIXME: s390/alpha/mips/parisc/poperpc/sh/xtensa need to be checked */
*plt_header_size = shdr_plt->sh_entsize;
*plt_entry_size = shdr_plt->sh_entsize;
break;
}
if (*plt_entry_size)
return true;
pr_debug("Missing PLT entry size for %s\n", dso->long_name);
return false;
}
static bool machine_is_x86(GElf_Half e_machine)
{
return e_machine == EM_386 || e_machine == EM_X86_64;
}
struct rela_dyn {
GElf_Addr offset;
u32 sym_idx;
};
struct rela_dyn_info {
struct dso *dso;
Elf_Data *plt_got_data;
u32 nr_entries;
struct rela_dyn *sorted;
Elf_Data *dynsym_data;
Elf_Data *dynstr_data;
Elf_Data *rela_dyn_data;
};
static void exit_rela_dyn(struct rela_dyn_info *di)
{
free(di->sorted);
}
static int cmp_offset(const void *a, const void *b)
{
const struct rela_dyn *va = a;
const struct rela_dyn *vb = b;
return va->offset < vb->offset ? -1 : (va->offset > vb->offset ? 1 : 0);
}
static int sort_rela_dyn(struct rela_dyn_info *di)
{
u32 i, n;
di->sorted = calloc(di->nr_entries, sizeof(di->sorted[0]));
if (!di->sorted)
return -1;
/* Get data for sorting: the offset and symbol index */
for (i = 0, n = 0; i < di->nr_entries; i++) {
GElf_Rela rela;
u32 sym_idx;
gelf_getrela(di->rela_dyn_data, i, &rela);
sym_idx = GELF_R_SYM(rela.r_info);
if (sym_idx) {
di->sorted[n].sym_idx = sym_idx;
di->sorted[n].offset = rela.r_offset;
n += 1;
}
}
/* Sort by offset */
di->nr_entries = n;
qsort(di->sorted, n, sizeof(di->sorted[0]), cmp_offset);
return 0;
}
static void get_rela_dyn_info(Elf *elf, GElf_Ehdr *ehdr, struct rela_dyn_info *di, Elf_Scn *scn)
{
GElf_Shdr rela_dyn_shdr;
GElf_Shdr shdr;
di->plt_got_data = elf_getdata(scn, NULL);
scn = elf_section_by_name(elf, ehdr, &rela_dyn_shdr, ".rela.dyn", NULL);
if (!scn || !rela_dyn_shdr.sh_link || !rela_dyn_shdr.sh_entsize)
return;
di->nr_entries = rela_dyn_shdr.sh_size / rela_dyn_shdr.sh_entsize;
di->rela_dyn_data = elf_getdata(scn, NULL);
scn = elf_getscn(elf, rela_dyn_shdr.sh_link);
if (!scn || !gelf_getshdr(scn, &shdr) || !shdr.sh_link)
return;
di->dynsym_data = elf_getdata(scn, NULL);
di->dynstr_data = elf_getdata(elf_getscn(elf, shdr.sh_link), NULL);
if (!di->plt_got_data || !di->dynstr_data || !di->dynsym_data || !di->rela_dyn_data)
return;
/* Sort into offset order */
sort_rela_dyn(di);
}
/* Get instruction displacement from a plt entry for x86_64 */
static u32 get_x86_64_plt_disp(const u8 *p)
{
u8 endbr64[] = {0xf3, 0x0f, 0x1e, 0xfa};
int n = 0;
/* Skip endbr64 */
if (!memcmp(p, endbr64, sizeof(endbr64)))
n += sizeof(endbr64);
/* Skip bnd prefix */
if (p[n] == 0xf2)
n += 1;
/* jmp with 4-byte displacement */
if (p[n] == 0xff && p[n + 1] == 0x25) {
u32 disp;
n += 2;
/* Also add offset from start of entry to end of instruction */
memcpy(&disp, p + n, sizeof(disp));
return n + 4 + le32toh(disp);
}
return 0;
}
static bool get_plt_got_name(GElf_Shdr *shdr, size_t i,
struct rela_dyn_info *di,
char *buf, size_t buf_sz)
{
struct rela_dyn vi, *vr;
const char *sym_name;
char *demangled;
GElf_Sym sym;
bool result;
u32 disp;
if (!di->sorted)
return false;
disp = get_x86_64_plt_disp(di->plt_got_data->d_buf + i);
if (!disp)
return false;
/* Compute target offset of the .plt.got entry */
vi.offset = shdr->sh_offset + di->plt_got_data->d_off + i + disp;
/* Find that offset in .rela.dyn (sorted by offset) */
vr = bsearch(&vi, di->sorted, di->nr_entries, sizeof(di->sorted[0]), cmp_offset);
if (!vr)
return false;
/* Get the associated symbol */
gelf_getsym(di->dynsym_data, vr->sym_idx, &sym);
sym_name = elf_sym__name(&sym, di->dynstr_data);
demangled = demangle_sym(di->dso, 0, sym_name);
if (demangled != NULL)
sym_name = demangled;
snprintf(buf, buf_sz, "%s@plt", sym_name);
result = *sym_name;
free(demangled);
return result;
}
static int dso__synthesize_plt_got_symbols(struct dso *dso, Elf *elf,
GElf_Ehdr *ehdr,
char *buf, size_t buf_sz)
{
struct rela_dyn_info di = { .dso = dso };
struct symbol *sym;
GElf_Shdr shdr;
Elf_Scn *scn;
int err = -1;
size_t i;
scn = elf_section_by_name(elf, ehdr, &shdr, ".plt.got", NULL);
if (!scn || !shdr.sh_entsize)
return 0;
if (ehdr->e_machine == EM_X86_64)
get_rela_dyn_info(elf, ehdr, &di, scn);
for (i = 0; i < shdr.sh_size; i += shdr.sh_entsize) {
if (!get_plt_got_name(&shdr, i, &di, buf, buf_sz))
snprintf(buf, buf_sz, "offset_%#" PRIx64 "@plt", (u64)shdr.sh_offset + i);
sym = symbol__new(shdr.sh_offset + i, shdr.sh_entsize, STB_GLOBAL, STT_FUNC, buf);
if (!sym)
goto out;
symbols__insert(&dso->symbols, sym);
}
err = 0;
out:
exit_rela_dyn(&di);
return err;
}
/*
* We need to check if we have a .dynsym, so that we can handle the
* .plt, synthesizing its symbols, that aren't on the symtabs (be it
* .dynsym or .symtab).
* And always look at the original dso, not at debuginfo packages, that
* have the PLT data stripped out (shdr_rel_plt.sh_type == SHT_NOBITS).
*/
int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss)
{
uint32_t idx;
GElf_Sym sym;
u64 plt_offset, plt_header_size, plt_entry_size;
GElf_Shdr shdr_plt, plt_sec_shdr;
struct symbol *f, *plt_sym;
GElf_Shdr shdr_rel_plt, shdr_dynsym;
Elf_Data *syms, *symstrs;
Elf_Scn *scn_plt_rel, *scn_symstrs, *scn_dynsym;
GElf_Ehdr ehdr;
char sympltname[1024];
Elf *elf;
int nr = 0, err = -1;
struct rel_info ri = { .is_rela = false };
bool lazy_plt;
elf = ss->elf;
ehdr = ss->ehdr;
if (!elf_section_by_name(elf, &ehdr, &shdr_plt, ".plt", NULL))
return 0;
/*
* A symbol from a previous section (e.g. .init) can have been expanded
* by symbols__fixup_end() to overlap .plt. Truncate it before adding
* a symbol for .plt header.
*/
f = dso__find_symbol_nocache(dso, shdr_plt.sh_offset);
if (f && f->start < shdr_plt.sh_offset && f->end > shdr_plt.sh_offset)
f->end = shdr_plt.sh_offset;
if (!get_plt_sizes(dso, &ehdr, &shdr_plt, &plt_header_size, &plt_entry_size))
return 0;
/* Add a symbol for .plt header */
plt_sym = symbol__new(shdr_plt.sh_offset, plt_header_size, STB_GLOBAL, STT_FUNC, ".plt");
if (!plt_sym)
goto out_elf_end;
symbols__insert(&dso->symbols, plt_sym);
/* Only x86 has .plt.got */
if (machine_is_x86(ehdr.e_machine) &&
dso__synthesize_plt_got_symbols(dso, elf, &ehdr, sympltname, sizeof(sympltname)))
goto out_elf_end;
/* Only x86 has .plt.sec */
if (machine_is_x86(ehdr.e_machine) &&
elf_section_by_name(elf, &ehdr, &plt_sec_shdr, ".plt.sec", NULL)) {
if (!get_plt_sizes(dso, &ehdr, &plt_sec_shdr, &plt_header_size, &plt_entry_size))
return 0;
/* Extend .plt symbol to entire .plt */
plt_sym->end = plt_sym->start + shdr_plt.sh_size;
/* Use .plt.sec offset */
plt_offset = plt_sec_shdr.sh_offset;
lazy_plt = false;
} else {
plt_offset = shdr_plt.sh_offset;
lazy_plt = true;
}
scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
".rela.plt", NULL);
if (scn_plt_rel == NULL) {
scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
".rel.plt", NULL);
if (scn_plt_rel == NULL)
return 0;
}
if (shdr_rel_plt.sh_type != SHT_RELA &&
shdr_rel_plt.sh_type != SHT_REL)
return 0;
if (!shdr_rel_plt.sh_link)
return 0;
if (shdr_rel_plt.sh_link == ss->dynsym_idx) {
scn_dynsym = ss->dynsym;
shdr_dynsym = ss->dynshdr;
} else if (shdr_rel_plt.sh_link == ss->symtab_idx) {
/*
* A static executable can have a .plt due to IFUNCs, in which
* case .symtab is used not .dynsym.
*/
scn_dynsym = ss->symtab;
shdr_dynsym = ss->symshdr;
} else {
goto out_elf_end;
}
if (!scn_dynsym)
return 0;
/*
* Fetch the relocation section to find the idxes to the GOT
* and the symbols in the .dynsym they refer to.
*/
ri.reldata = elf_getdata(scn_plt_rel, NULL);
if (!ri.reldata)
goto out_elf_end;
syms = elf_getdata(scn_dynsym, NULL);
if (syms == NULL)
goto out_elf_end;
scn_symstrs = elf_getscn(elf, shdr_dynsym.sh_link);
if (scn_symstrs == NULL)
goto out_elf_end;
symstrs = elf_getdata(scn_symstrs, NULL);
if (symstrs == NULL)
goto out_elf_end;
if (symstrs->d_size == 0)
goto out_elf_end;
ri.nr_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
ri.is_rela = shdr_rel_plt.sh_type == SHT_RELA;
if (lazy_plt) {
/*
* Assume a .plt with the same number of entries as the number
* of relocation entries is not lazy and does not have a header.
*/
if (ri.nr_entries * plt_entry_size == shdr_plt.sh_size)
dso__delete_symbol(dso, plt_sym);
else
plt_offset += plt_header_size;
}
/*
* x86 doesn't insert IFUNC relocations in .plt order, so sort to get
* back in order.
*/
if (machine_is_x86(ehdr.e_machine) && sort_rel(&ri))
goto out_elf_end;
for (idx = 0; idx < ri.nr_entries; idx++) {
const char *elf_name = NULL;
char *demangled = NULL;
gelf_getsym(syms, get_rel_symidx(&ri, idx), &sym);
elf_name = elf_sym__name(&sym, symstrs);
demangled = demangle_sym(dso, 0, elf_name);
if (demangled)
elf_name = demangled;
if (*elf_name)
snprintf(sympltname, sizeof(sympltname), "%s@plt", elf_name);
else if (!get_ifunc_name(elf, dso, &ehdr, &ri, sympltname, sizeof(sympltname)))
snprintf(sympltname, sizeof(sympltname),
"offset_%#" PRIx64 "@plt", plt_offset);
free(demangled);
f = symbol__new(plt_offset, plt_entry_size, STB_GLOBAL, STT_FUNC, sympltname);
if (!f)
goto out_elf_end;
plt_offset += plt_entry_size;
symbols__insert(&dso->symbols, f);
++nr;
}
err = 0;
out_elf_end:
exit_rel(&ri);
if (err == 0)
return nr;
pr_debug("%s: problems reading %s PLT info.\n",
__func__, dso->long_name);
return 0;
}
char *dso__demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
{
return demangle_sym(dso, kmodule, elf_name);
}
/*
* Align offset to 4 bytes as needed for note name and descriptor data.
*/
#define NOTE_ALIGN(n) (((n) + 3) & -4U)
static int elf_read_build_id(Elf *elf, void *bf, size_t size)
{
int err = -1;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
Elf_Data *data;
Elf_Scn *sec;
Elf_Kind ek;
void *ptr;
if (size < BUILD_ID_SIZE)
goto out;
ek = elf_kind(elf);
if (ek != ELF_K_ELF)
goto out;
if (gelf_getehdr(elf, &ehdr) == NULL) {
pr_err("%s: cannot get elf header.\n", __func__);
goto out;
}
/*
* Check following sections for notes:
* '.note.gnu.build-id'
* '.notes'
* '.note' (VDSO specific)
*/
do {
sec = elf_section_by_name(elf, &ehdr, &shdr,
".note.gnu.build-id", NULL);
if (sec)
break;
sec = elf_section_by_name(elf, &ehdr, &shdr,
".notes", NULL);
if (sec)
break;
sec = elf_section_by_name(elf, &ehdr, &shdr,
".note", NULL);
if (sec)
break;
return err;
} while (0);
data = elf_getdata(sec, NULL);
if (data == NULL)
goto out;
ptr = data->d_buf;
while (ptr < (data->d_buf + data->d_size)) {
GElf_Nhdr *nhdr = ptr;
size_t namesz = NOTE_ALIGN(nhdr->n_namesz),
descsz = NOTE_ALIGN(nhdr->n_descsz);
const char *name;
ptr += sizeof(*nhdr);
name = ptr;
ptr += namesz;
if (nhdr->n_type == NT_GNU_BUILD_ID &&
nhdr->n_namesz == sizeof("GNU")) {
if (memcmp(name, "GNU", sizeof("GNU")) == 0) {
size_t sz = min(size, descsz);
memcpy(bf, ptr, sz);
memset(bf + sz, 0, size - sz);
err = sz;
break;
}
}
ptr += descsz;
}
out:
return err;
}
#ifdef HAVE_LIBBFD_BUILDID_SUPPORT
static int read_build_id(const char *filename, struct build_id *bid)
{
size_t size = sizeof(bid->data);
int err = -1;
bfd *abfd;
abfd = bfd_openr(filename, NULL);
if (!abfd)
return -1;
if (!bfd_check_format(abfd, bfd_object)) {
pr_debug2("%s: cannot read %s bfd file.\n", __func__, filename);
goto out_close;
}
if (!abfd->build_id || abfd->build_id->size > size)
goto out_close;
memcpy(bid->data, abfd->build_id->data, abfd->build_id->size);
memset(bid->data + abfd->build_id->size, 0, size - abfd->build_id->size);
err = bid->size = abfd->build_id->size;
out_close:
bfd_close(abfd);
return err;
}
#else // HAVE_LIBBFD_BUILDID_SUPPORT
static int read_build_id(const char *filename, struct build_id *bid)
{
size_t size = sizeof(bid->data);
int fd, err = -1;
Elf *elf;
if (size < BUILD_ID_SIZE)
goto out;
fd = open(filename, O_RDONLY);
if (fd < 0)
goto out;
elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
if (elf == NULL) {
pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
goto out_close;
}
err = elf_read_build_id(elf, bid->data, size);
if (err > 0)
bid->size = err;
elf_end(elf);
out_close:
close(fd);
out:
return err;
}
#endif // HAVE_LIBBFD_BUILDID_SUPPORT
int filename__read_build_id(const char *filename, struct build_id *bid)
{
struct kmod_path m = { .name = NULL, };
char path[PATH_MAX];
int err;
if (!filename)
return -EFAULT;
err = kmod_path__parse(&m, filename);
if (err)
return -1;
if (m.comp) {
int error = 0, fd;
fd = filename__decompress(filename, path, sizeof(path), m.comp, &error);
if (fd < 0) {
pr_debug("Failed to decompress (error %d) %s\n",
error, filename);
return -1;
}
close(fd);
filename = path;
}
err = read_build_id(filename, bid);
if (m.comp)
unlink(filename);
return err;
}
int sysfs__read_build_id(const char *filename, struct build_id *bid)
{
size_t size = sizeof(bid->data);
int fd, err = -1;
fd = open(filename, O_RDONLY);
if (fd < 0)
goto out;
while (1) {
char bf[BUFSIZ];
GElf_Nhdr nhdr;
size_t namesz, descsz;
if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr))
break;
namesz = NOTE_ALIGN(nhdr.n_namesz);
descsz = NOTE_ALIGN(nhdr.n_descsz);
if (nhdr.n_type == NT_GNU_BUILD_ID &&
nhdr.n_namesz == sizeof("GNU")) {
if (read(fd, bf, namesz) != (ssize_t)namesz)
break;
if (memcmp(bf, "GNU", sizeof("GNU")) == 0) {
size_t sz = min(descsz, size);
if (read(fd, bid->data, sz) == (ssize_t)sz) {
memset(bid->data + sz, 0, size - sz);
bid->size = sz;
err = 0;
break;
}
} else if (read(fd, bf, descsz) != (ssize_t)descsz)
break;
} else {
int n = namesz + descsz;
if (n > (int)sizeof(bf)) {
n = sizeof(bf);
pr_debug("%s: truncating reading of build id in sysfs file %s: n_namesz=%u, n_descsz=%u.\n",
__func__, filename, nhdr.n_namesz, nhdr.n_descsz);
}
if (read(fd, bf, n) != n)
break;
}
}
close(fd);
out:
return err;
}
#ifdef HAVE_LIBBFD_SUPPORT
int filename__read_debuglink(const char *filename, char *debuglink,
size_t size)
{
int err = -1;
asection *section;
bfd *abfd;
abfd = bfd_openr(filename, NULL);
if (!abfd)
return -1;
if (!bfd_check_format(abfd, bfd_object)) {
pr_debug2("%s: cannot read %s bfd file.\n", __func__, filename);
goto out_close;
}
section = bfd_get_section_by_name(abfd, ".gnu_debuglink");
if (!section)
goto out_close;
if (section->size > size)
goto out_close;
if (!bfd_get_section_contents(abfd, section, debuglink, 0,
section->size))
goto out_close;
err = 0;
out_close:
bfd_close(abfd);
return err;
}
#else
int filename__read_debuglink(const char *filename, char *debuglink,
size_t size)
{
int fd, err = -1;
Elf *elf;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
Elf_Data *data;
Elf_Scn *sec;
Elf_Kind ek;
fd = open(filename, O_RDONLY);
if (fd < 0)
goto out;
elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
if (elf == NULL) {
pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
goto out_close;
}
ek = elf_kind(elf);
if (ek != ELF_K_ELF)
goto out_elf_end;
if (gelf_getehdr(elf, &ehdr) == NULL) {
pr_err("%s: cannot get elf header.\n", __func__);
goto out_elf_end;
}
sec = elf_section_by_name(elf, &ehdr, &shdr,
".gnu_debuglink", NULL);
if (sec == NULL)
goto out_elf_end;
data = elf_getdata(sec, NULL);
if (data == NULL)
goto out_elf_end;
/* the start of this section is a zero-terminated string */
strncpy(debuglink, data->d_buf, size);
err = 0;
out_elf_end:
elf_end(elf);
out_close:
close(fd);
out:
return err;
}
#endif
static int dso__swap_init(struct dso *dso, unsigned char eidata)
{
static unsigned int const endian = 1;
dso->needs_swap = DSO_SWAP__NO;
switch (eidata) {
case ELFDATA2LSB:
/* We are big endian, DSO is little endian. */
if (*(unsigned char const *)&endian != 1)
dso->needs_swap = DSO_SWAP__YES;
break;
case ELFDATA2MSB:
/* We are little endian, DSO is big endian. */
if (*(unsigned char const *)&endian != 0)
dso->needs_swap = DSO_SWAP__YES;
break;
default:
pr_err("unrecognized DSO data encoding %d\n", eidata);
return -EINVAL;
}
return 0;
}
bool symsrc__possibly_runtime(struct symsrc *ss)
{
return ss->dynsym || ss->opdsec;
}
bool symsrc__has_symtab(struct symsrc *ss)
{
return ss->symtab != NULL;
}
void symsrc__destroy(struct symsrc *ss)
{
zfree(&ss->name);
elf_end(ss->elf);
close(ss->fd);
}
bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
{
/*
* Usually vmlinux is an ELF file with type ET_EXEC for most
* architectures; except Arm64 kernel is linked with option
* '-share', so need to check type ET_DYN.
*/
return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL ||
ehdr.e_type == ET_DYN;
}
int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
enum dso_binary_type type)
{
GElf_Ehdr ehdr;
Elf *elf;
int fd;
if (dso__needs_decompress(dso)) {
fd = dso__decompress_kmodule_fd(dso, name);
if (fd < 0)
return -1;
type = dso->symtab_type;
} else {
fd = open(name, O_RDONLY);
if (fd < 0) {
dso->load_errno = errno;
return -1;
}
}
elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
if (elf == NULL) {
pr_debug("%s: cannot read %s ELF file.\n", __func__, name);
dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;
goto out_close;
}
if (gelf_getehdr(elf, &ehdr) == NULL) {
dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;
pr_debug("%s: cannot get elf header.\n", __func__);
goto out_elf_end;
}
if (dso__swap_init(dso, ehdr.e_ident[EI_DATA])) {
dso->load_errno = DSO_LOAD_ERRNO__INTERNAL_ERROR;
goto out_elf_end;
}
/* Always reject images with a mismatched build-id: */
if (dso->has_build_id && !symbol_conf.ignore_vmlinux_buildid) {
u8 build_id[BUILD_ID_SIZE];
struct build_id bid;
int size;
size = elf_read_build_id(elf, build_id, BUILD_ID_SIZE);
if (size <= 0) {
dso->load_errno = DSO_LOAD_ERRNO__CANNOT_READ_BUILDID;
goto out_elf_end;
}
build_id__init(&bid, build_id, size);
if (!dso__build_id_equal(dso, &bid)) {
pr_debug("%s: build id mismatch for %s.\n", __func__, name);
dso->load_errno = DSO_LOAD_ERRNO__MISMATCHING_BUILDID;
goto out_elf_end;
}
}
ss->is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
ss->symtab_idx = 0;
ss->symtab = elf_section_by_name(elf, &ehdr, &ss->symshdr, ".symtab",
&ss->symtab_idx);
if (ss->symshdr.sh_type != SHT_SYMTAB)
ss->symtab = NULL;
ss->dynsym_idx = 0;
ss->dynsym = elf_section_by_name(elf, &ehdr, &ss->dynshdr, ".dynsym",
&ss->dynsym_idx);
if (ss->dynshdr.sh_type != SHT_DYNSYM)
ss->dynsym = NULL;
ss->opdidx = 0;
ss->opdsec = elf_section_by_name(elf, &ehdr, &ss->opdshdr, ".opd",
&ss->opdidx);
if (ss->opdshdr.sh_type != SHT_PROGBITS)
ss->opdsec = NULL;
if (dso->kernel == DSO_SPACE__USER)
ss->adjust_symbols = true;
else
ss->adjust_symbols = elf__needs_adjust_symbols(ehdr);
ss->name = strdup(name);
if (!ss->name) {
dso->load_errno = errno;
goto out_elf_end;
}
ss->elf = elf;
ss->fd = fd;
ss->ehdr = ehdr;
ss->type = type;
return 0;
out_elf_end:
elf_end(elf);
out_close:
close(fd);
return -1;
}
/**
* ref_reloc_sym_not_found - has kernel relocation symbol been found.
* @kmap: kernel maps and relocation reference symbol
*
* This function returns %true if we are dealing with the kernel maps and the
* relocation reference symbol has not yet been found. Otherwise %false is
* returned.
*/
static bool ref_reloc_sym_not_found(struct kmap *kmap)
{
return kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
!kmap->ref_reloc_sym->unrelocated_addr;
}
/**
* ref_reloc - kernel relocation offset.
* @kmap: kernel maps and relocation reference symbol
*
* This function returns the offset of kernel addresses as determined by using
* the relocation reference symbol i.e. if the kernel has not been relocated
* then the return value is zero.
*/
static u64 ref_reloc(struct kmap *kmap)
{
if (kmap && kmap->ref_reloc_sym &&
kmap->ref_reloc_sym->unrelocated_addr)
return kmap->ref_reloc_sym->addr -
kmap->ref_reloc_sym->unrelocated_addr;
return 0;
}
void __weak arch__sym_update(struct symbol *s __maybe_unused,
GElf_Sym *sym __maybe_unused) { }
static int dso__process_kernel_symbol(struct dso *dso, struct map *map,
GElf_Sym *sym, GElf_Shdr *shdr,
struct maps *kmaps, struct kmap *kmap,
struct dso **curr_dsop, struct map **curr_mapp,
const char *section_name,
bool adjust_kernel_syms, bool kmodule, bool *remap_kernel)
{
struct dso *curr_dso = *curr_dsop;
struct map *curr_map;
char dso_name[PATH_MAX];
/* Adjust symbol to map to file offset */
if (adjust_kernel_syms)
sym->st_value -= shdr->sh_addr - shdr->sh_offset;
if (strcmp(section_name, (curr_dso->short_name + dso->short_name_len)) == 0)
return 0;
if (strcmp(section_name, ".text") == 0) {
/*
* The initial kernel mapping is based on
* kallsyms and identity maps. Overwrite it to
* map to the kernel dso.
*/
if (*remap_kernel && dso->kernel && !kmodule) {
*remap_kernel = false;
map->start = shdr->sh_addr + ref_reloc(kmap);
map->end = map->start + shdr->sh_size;
map->pgoff = shdr->sh_offset;
map->map_ip = map__map_ip;
map->unmap_ip = map__unmap_ip;
/* Ensure maps are correctly ordered */
if (kmaps) {
map__get(map);
maps__remove(kmaps, map);
maps__insert(kmaps, map);
map__put(map);
}
}
/*
* The initial module mapping is based on
* /proc/modules mapped to offset zero.
* Overwrite it to map to the module dso.
*/
if (*remap_kernel && kmodule) {
*remap_kernel = false;
map->pgoff = shdr->sh_offset;
}
*curr_mapp = map;
*curr_dsop = dso;
return 0;
}
if (!kmap)
return 0;
snprintf(dso_name, sizeof(dso_name), "%s%s", dso->short_name, section_name);
curr_map = maps__find_by_name(kmaps, dso_name);
if (curr_map == NULL) {
u64 start = sym->st_value;
if (kmodule)
start += map->start + shdr->sh_offset;
curr_dso = dso__new(dso_name);
if (curr_dso == NULL)
return -1;
curr_dso->kernel = dso->kernel;
curr_dso->long_name = dso->long_name;
curr_dso->long_name_len = dso->long_name_len;
curr_map = map__new2(start, curr_dso);
dso__put(curr_dso);
if (curr_map == NULL)
return -1;
if (curr_dso->kernel)
map__kmap(curr_map)->kmaps = kmaps;
if (adjust_kernel_syms) {
curr_map->start = shdr->sh_addr + ref_reloc(kmap);
curr_map->end = curr_map->start + shdr->sh_size;
curr_map->pgoff = shdr->sh_offset;
} else {
curr_map->map_ip = curr_map->unmap_ip = identity__map_ip;
}
curr_dso->symtab_type = dso->symtab_type;
maps__insert(kmaps, curr_map);
/*
* Add it before we drop the reference to curr_map, i.e. while
* we still are sure to have a reference to this DSO via
* *curr_map->dso.
*/
dsos__add(&kmaps->machine->dsos, curr_dso);
/* kmaps already got it */
map__put(curr_map);
dso__set_loaded(curr_dso);
*curr_mapp = curr_map;
*curr_dsop = curr_dso;
} else
*curr_dsop = curr_map->dso;
return 0;
}
static int
dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
struct symsrc *runtime_ss, int kmodule, int dynsym)
{
struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
struct maps *kmaps = kmap ? map__kmaps(map) : NULL;
struct map *curr_map = map;
struct dso *curr_dso = dso;
Elf_Data *symstrs, *secstrs, *secstrs_run, *secstrs_sym;
uint32_t nr_syms;
int err = -1;
uint32_t idx;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
GElf_Shdr tshdr;
Elf_Data *syms, *opddata = NULL;
GElf_Sym sym;
Elf_Scn *sec, *sec_strndx;
Elf *elf;
int nr = 0;
bool remap_kernel = false, adjust_kernel_syms = false;
if (kmap && !kmaps)
return -1;
elf = syms_ss->elf;
ehdr = syms_ss->ehdr;
if (dynsym) {
sec = syms_ss->dynsym;
shdr = syms_ss->dynshdr;
} else {
sec = syms_ss->symtab;
shdr = syms_ss->symshdr;
}
if (elf_section_by_name(runtime_ss->elf, &runtime_ss->ehdr, &tshdr,
".text", NULL))
dso->text_offset = tshdr.sh_addr - tshdr.sh_offset;
if (runtime_ss->opdsec)
opddata = elf_rawdata(runtime_ss->opdsec, NULL);
syms = elf_getdata(sec, NULL);
if (syms == NULL)
goto out_elf_end;
sec = elf_getscn(elf, shdr.sh_link);
if (sec == NULL)
goto out_elf_end;
symstrs = elf_getdata(sec, NULL);
if (symstrs == NULL)
goto out_elf_end;
sec_strndx = elf_getscn(runtime_ss->elf, runtime_ss->ehdr.e_shstrndx);
if (sec_strndx == NULL)
goto out_elf_end;
secstrs_run = elf_getdata(sec_strndx, NULL);
if (secstrs_run == NULL)
goto out_elf_end;
sec_strndx = elf_getscn(elf, ehdr.e_shstrndx);
if (sec_strndx == NULL)
goto out_elf_end;
secstrs_sym = elf_getdata(sec_strndx, NULL);
if (secstrs_sym == NULL)
goto out_elf_end;
nr_syms = shdr.sh_size / shdr.sh_entsize;
memset(&sym, 0, sizeof(sym));
/*
* The kernel relocation symbol is needed in advance in order to adjust
* kernel maps correctly.
*/
if (ref_reloc_sym_not_found(kmap)) {
elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
const char *elf_name = elf_sym__name(&sym, symstrs);
if (strcmp(elf_name, kmap->ref_reloc_sym->name))
continue;
kmap->ref_reloc_sym->unrelocated_addr = sym.st_value;
map->reloc = kmap->ref_reloc_sym->addr -
kmap->ref_reloc_sym->unrelocated_addr;
break;
}
}
/*
* Handle any relocation of vdso necessary because older kernels
* attempted to prelink vdso to its virtual address.
*/
if (dso__is_vdso(dso))
map->reloc = map->start - dso->text_offset;
dso->adjust_symbols = runtime_ss->adjust_symbols || ref_reloc(kmap);
/*
* Initial kernel and module mappings do not map to the dso.
* Flag the fixups.
*/
if (dso->kernel) {
remap_kernel = true;
adjust_kernel_syms = dso->adjust_symbols;
}
elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
struct symbol *f;
const char *elf_name = elf_sym__name(&sym, symstrs);
char *demangled = NULL;
int is_label = elf_sym__is_label(&sym);
const char *section_name;
bool used_opd = false;
if (!is_label && !elf_sym__filter(&sym))
continue;
/* Reject ARM ELF "mapping symbols": these aren't unique and
* don't identify functions, so will confuse the profile
* output: */
if (ehdr.e_machine == EM_ARM || ehdr.e_machine == EM_AARCH64) {
if (elf_name[0] == '$' && strchr("adtx", elf_name[1])
&& (elf_name[2] == '\0' || elf_name[2] == '.'))
continue;
}
if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) {
u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr;
u64 *opd = opddata->d_buf + offset;
sym.st_value = DSO__SWAP(dso, u64, *opd);
sym.st_shndx = elf_addr_to_index(runtime_ss->elf,
sym.st_value);
used_opd = true;
}
/*
* When loading symbols in a data mapping, ABS symbols (which
* has a value of SHN_ABS in its st_shndx) failed at
* elf_getscn(). And it marks the loading as a failure so
* already loaded symbols cannot be fixed up.
*
* I'm not sure what should be done. Just ignore them for now.
* - Namhyung Kim
*/
if (sym.st_shndx == SHN_ABS)
continue;
sec = elf_getscn(syms_ss->elf, sym.st_shndx);
if (!sec)
goto out_elf_end;
gelf_getshdr(sec, &shdr);
/*
* If the attribute bit SHF_ALLOC is not set, the section
* doesn't occupy memory during process execution.
* E.g. ".gnu.warning.*" section is used by linker to generate
* warnings when calling deprecated functions, the symbols in
* the section aren't loaded to memory during process execution,
* so skip them.
*/
if (!(shdr.sh_flags & SHF_ALLOC))
continue;
secstrs = secstrs_sym;
/*
* We have to fallback to runtime when syms' section header has
* NOBITS set. NOBITS results in file offset (sh_offset) not
* being incremented. So sh_offset used below has different
* values for syms (invalid) and runtime (valid).
*/
if (shdr.sh_type == SHT_NOBITS) {
sec = elf_getscn(runtime_ss->elf, sym.st_shndx);
if (!sec)
goto out_elf_end;
gelf_getshdr(sec, &shdr);
secstrs = secstrs_run;
}
if (is_label && !elf_sec__filter(&shdr, secstrs))
continue;
section_name = elf_sec__name(&shdr, secstrs);
/* On ARM, symbols for thumb functions have 1 added to
* the symbol address as a flag - remove it */
if ((ehdr.e_machine == EM_ARM) &&
(GELF_ST_TYPE(sym.st_info) == STT_FUNC) &&
(sym.st_value & 1))
--sym.st_value;
if (dso->kernel) {
if (dso__process_kernel_symbol(dso, map, &sym, &shdr, kmaps, kmap, &curr_dso, &curr_map,
section_name, adjust_kernel_syms, kmodule, &remap_kernel))
goto out_elf_end;
} else if ((used_opd && runtime_ss->adjust_symbols) ||
(!used_opd && syms_ss->adjust_symbols)) {
GElf_Phdr phdr;
if (elf_read_program_header(runtime_ss->elf,
(u64)sym.st_value, &phdr)) {
pr_debug4("%s: failed to find program header for "
"symbol: %s st_value: %#" PRIx64 "\n",
__func__, elf_name, (u64)sym.st_value);
pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
"sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n",
__func__, (u64)sym.st_value, (u64)shdr.sh_addr,
(u64)shdr.sh_offset);
/*
* Fail to find program header, let's rollback
* to use shdr.sh_addr and shdr.sh_offset to
* calibrate symbol's file address, though this
* is not necessary for normal C ELF file, we
* still need to handle java JIT symbols in this
* case.
*/
sym.st_value -= shdr.sh_addr - shdr.sh_offset;
} else {
pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
"p_vaddr: %#" PRIx64 " p_offset: %#" PRIx64 "\n",
__func__, (u64)sym.st_value, (u64)phdr.p_vaddr,
(u64)phdr.p_offset);
sym.st_value -= phdr.p_vaddr - phdr.p_offset;
}
}
demangled = demangle_sym(dso, kmodule, elf_name);
if (demangled != NULL)
elf_name = demangled;
f = symbol__new(sym.st_value, sym.st_size,
GELF_ST_BIND(sym.st_info),
GELF_ST_TYPE(sym.st_info), elf_name);
free(demangled);
if (!f)
goto out_elf_end;
arch__sym_update(f, &sym);
__symbols__insert(&curr_dso->symbols, f, dso->kernel);
nr++;
}
/*
* For misannotated, zeroed, ASM function sizes.
*/
if (nr > 0) {
symbols__fixup_end(&dso->symbols, false);
symbols__fixup_duplicate(&dso->symbols);
if (kmap) {
/*
* We need to fixup this here too because we create new
* maps here, for things like vsyscall sections.
*/
maps__fixup_end(kmaps);
}
}
err = nr;
out_elf_end:
return err;
}
int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss,
struct symsrc *runtime_ss, int kmodule)
{
int nr = 0;
int err = -1;
dso->symtab_type = syms_ss->type;
dso->is_64_bit = syms_ss->is_64_bit;
dso->rel = syms_ss->ehdr.e_type == ET_REL;
/*
* Modules may already have symbols from kallsyms, but those symbols
* have the wrong values for the dso maps, so remove them.
*/
if (kmodule && syms_ss->symtab)
symbols__delete(&dso->symbols);
if (!syms_ss->symtab) {
/*
* If the vmlinux is stripped, fail so we will fall back
* to using kallsyms. The vmlinux runtime symbols aren't
* of much use.
*/
if (dso->kernel)
return err;
} else {
err = dso__load_sym_internal(dso, map, syms_ss, runtime_ss,
kmodule, 0);
if (err < 0)
return err;
nr = err;
}
if (syms_ss->dynsym) {
err = dso__load_sym_internal(dso, map, syms_ss, runtime_ss,
kmodule, 1);
if (err < 0)
return err;
err += nr;
}
return err;
}
static int elf_read_maps(Elf *elf, bool exe, mapfn_t mapfn, void *data)
{
GElf_Phdr phdr;
size_t i, phdrnum;
int err;
u64 sz;
if (elf_getphdrnum(elf, &phdrnum))
return -1;
for (i = 0; i < phdrnum; i++) {
if (gelf_getphdr(elf, i, &phdr) == NULL)
return -1;
if (phdr.p_type != PT_LOAD)
continue;
if (exe) {
if (!(phdr.p_flags & PF_X))
continue;
} else {
if (!(phdr.p_flags & PF_R))
continue;
}
sz = min(phdr.p_memsz, phdr.p_filesz);
if (!sz)
continue;
err = mapfn(phdr.p_vaddr, sz, phdr.p_offset, data);
if (err)
return err;
}
return 0;
}
int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
bool *is_64_bit)
{
int err;
Elf *elf;
elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
if (elf == NULL)
return -1;
if (is_64_bit)
*is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
err = elf_read_maps(elf, exe, mapfn, data);
elf_end(elf);
return err;
}
enum dso_type dso__type_fd(int fd)
{
enum dso_type dso_type = DSO__TYPE_UNKNOWN;
GElf_Ehdr ehdr;
Elf_Kind ek;
Elf *elf;
elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
if (elf == NULL)
goto out;
ek = elf_kind(elf);
if (ek != ELF_K_ELF)
goto out_end;
if (gelf_getclass(elf) == ELFCLASS64) {
dso_type = DSO__TYPE_64BIT;
goto out_end;
}
if (gelf_getehdr(elf, &ehdr) == NULL)
goto out_end;
if (ehdr.e_machine == EM_X86_64)
dso_type = DSO__TYPE_X32BIT;
else
dso_type = DSO__TYPE_32BIT;
out_end:
elf_end(elf);
out:
return dso_type;
}
static int copy_bytes(int from, off_t from_offs, int to, off_t to_offs, u64 len)
{
ssize_t r;
size_t n;
int err = -1;
char *buf = malloc(page_size);
if (buf == NULL)
return -1;
if (lseek(to, to_offs, SEEK_SET) != to_offs)
goto out;
if (lseek(from, from_offs, SEEK_SET) != from_offs)
goto out;
while (len) {
n = page_size;
if (len < n)
n = len;
/* Use read because mmap won't work on proc files */
r = read(from, buf, n);
if (r < 0)
goto out;
if (!r)
break;
n = r;
r = write(to, buf, n);
if (r < 0)
goto out;
if ((size_t)r != n)
goto out;
len -= n;
}
err = 0;
out:
free(buf);
return err;
}
struct kcore {
int fd;
int elfclass;
Elf *elf;
GElf_Ehdr ehdr;
};
static int kcore__open(struct kcore *kcore, const char *filename)
{
GElf_Ehdr *ehdr;
kcore->fd = open(filename, O_RDONLY);
if (kcore->fd == -1)
return -1;
kcore->elf = elf_begin(kcore->fd, ELF_C_READ, NULL);
if (!kcore->elf)
goto out_close;
kcore->elfclass = gelf_getclass(kcore->elf);
if (kcore->elfclass == ELFCLASSNONE)
goto out_end;
ehdr = gelf_getehdr(kcore->elf, &kcore->ehdr);
if (!ehdr)
goto out_end;
return 0;
out_end:
elf_end(kcore->elf);
out_close:
close(kcore->fd);
return -1;
}
static int kcore__init(struct kcore *kcore, char *filename, int elfclass,
bool temp)
{
kcore->elfclass = elfclass;
if (temp)
kcore->fd = mkstemp(filename);
else
kcore->fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0400);
if (kcore->fd == -1)
return -1;
kcore->elf = elf_begin(kcore->fd, ELF_C_WRITE, NULL);
if (!kcore->elf)
goto out_close;
if (!gelf_newehdr(kcore->elf, elfclass))
goto out_end;
memset(&kcore->ehdr, 0, sizeof(GElf_Ehdr));
return 0;
out_end:
elf_end(kcore->elf);
out_close:
close(kcore->fd);
unlink(filename);
return -1;
}
static void kcore__close(struct kcore *kcore)
{
elf_end(kcore->elf);
close(kcore->fd);
}
static int kcore__copy_hdr(struct kcore *from, struct kcore *to, size_t count)
{
GElf_Ehdr *ehdr = &to->ehdr;
GElf_Ehdr *kehdr = &from->ehdr;
memcpy(ehdr->e_ident, kehdr->e_ident, EI_NIDENT);
ehdr->e_type = kehdr->e_type;
ehdr->e_machine = kehdr->e_machine;
ehdr->e_version = kehdr->e_version;
ehdr->e_entry = 0;
ehdr->e_shoff = 0;
ehdr->e_flags = kehdr->e_flags;
ehdr->e_phnum = count;
ehdr->e_shentsize = 0;
ehdr->e_shnum = 0;
ehdr->e_shstrndx = 0;
if (from->elfclass == ELFCLASS32) {
ehdr->e_phoff = sizeof(Elf32_Ehdr);
ehdr->e_ehsize = sizeof(Elf32_Ehdr);
ehdr->e_phentsize = sizeof(Elf32_Phdr);
} else {
ehdr->e_phoff = sizeof(Elf64_Ehdr);
ehdr->e_ehsize = sizeof(Elf64_Ehdr);
ehdr->e_phentsize = sizeof(Elf64_Phdr);
}
if (!gelf_update_ehdr(to->elf, ehdr))
return -1;
if (!gelf_newphdr(to->elf, count))
return -1;
return 0;
}
static int kcore__add_phdr(struct kcore *kcore, int idx, off_t offset,
u64 addr, u64 len)
{
GElf_Phdr phdr = {
.p_type = PT_LOAD,
.p_flags = PF_R | PF_W | PF_X,
.p_offset = offset,
.p_vaddr = addr,
.p_paddr = 0,
.p_filesz = len,
.p_memsz = len,
.p_align = page_size,
};
if (!gelf_update_phdr(kcore->elf, idx, &phdr))
return -1;
return 0;
}
static off_t kcore__write(struct kcore *kcore)
{
return elf_update(kcore->elf, ELF_C_WRITE);
}
struct phdr_data {
off_t offset;
off_t rel;
u64 addr;
u64 len;
struct list_head node;
struct phdr_data *remaps;
};
struct sym_data {
u64 addr;
struct list_head node;
};
struct kcore_copy_info {
u64 stext;
u64 etext;
u64 first_symbol;
u64 last_symbol;
u64 first_module;
u64 first_module_symbol;
u64 last_module_symbol;
size_t phnum;
struct list_head phdrs;
struct list_head syms;
};
#define kcore_copy__for_each_phdr(k, p) \
list_for_each_entry((p), &(k)->phdrs, node)
static struct phdr_data *phdr_data__new(u64 addr, u64 len, off_t offset)
{
struct phdr_data *p = zalloc(sizeof(*p));
if (p) {
p->addr = addr;
p->len = len;
p->offset = offset;
}
return p;
}
static struct phdr_data *kcore_copy_info__addnew(struct kcore_copy_info *kci,
u64 addr, u64 len,
off_t offset)
{
struct phdr_data *p = phdr_data__new(addr, len, offset);
if (p)
list_add_tail(&p->node, &kci->phdrs);
return p;
}
static void kcore_copy__free_phdrs(struct kcore_copy_info *kci)
{
struct phdr_data *p, *tmp;
list_for_each_entry_safe(p, tmp, &kci->phdrs, node) {
list_del_init(&p->node);
free(p);
}
}
static struct sym_data *kcore_copy__new_sym(struct kcore_copy_info *kci,
u64 addr)
{
struct sym_data *s = zalloc(sizeof(*s));
if (s) {
s->addr = addr;
list_add_tail(&s->node, &kci->syms);
}
return s;
}
static void kcore_copy__free_syms(struct kcore_copy_info *kci)
{
struct sym_data *s, *tmp;
list_for_each_entry_safe(s, tmp, &kci->syms, node) {
list_del_init(&s->node);
free(s);
}
}
static int kcore_copy__process_kallsyms(void *arg, const char *name, char type,
u64 start)
{
struct kcore_copy_info *kci = arg;
if (!kallsyms__is_function(type))
return 0;
if (strchr(name, '[')) {
if (!kci->first_module_symbol || start < kci->first_module_symbol)
kci->first_module_symbol = start;
if (start > kci->last_module_symbol)
kci->last_module_symbol = start;
return 0;
}
if (!kci->first_symbol || start < kci->first_symbol)
kci->first_symbol = start;
if (!kci->last_symbol || start > kci->last_symbol)
kci->last_symbol = start;
if (!strcmp(name, "_stext")) {
kci->stext = start;
return 0;
}
if (!strcmp(name, "_etext")) {
kci->etext = start;
return 0;
}
if (is_entry_trampoline(name) && !kcore_copy__new_sym(kci, start))
return -1;
return 0;
}
static int kcore_copy__parse_kallsyms(struct kcore_copy_info *kci,
const char *dir)
{
char kallsyms_filename[PATH_MAX];
scnprintf(kallsyms_filename, PATH_MAX, "%s/kallsyms", dir);
if (symbol__restricted_filename(kallsyms_filename, "/proc/kallsyms"))
return -1;
if (kallsyms__parse(kallsyms_filename, kci,
kcore_copy__process_kallsyms) < 0)
return -1;
return 0;
}
static int kcore_copy__process_modules(void *arg,
const char *name __maybe_unused,
u64 start, u64 size __maybe_unused)
{
struct kcore_copy_info *kci = arg;
if (!kci->first_module || start < kci->first_module)
kci->first_module = start;
return 0;
}
static int kcore_copy__parse_modules(struct kcore_copy_info *kci,
const char *dir)
{
char modules_filename[PATH_MAX];
scnprintf(modules_filename, PATH_MAX, "%s/modules", dir);
if (symbol__restricted_filename(modules_filename, "/proc/modules"))
return -1;
if (modules__parse(modules_filename, kci,
kcore_copy__process_modules) < 0)
return -1;
return 0;
}
static int kcore_copy__map(struct kcore_copy_info *kci, u64 start, u64 end,
u64 pgoff, u64 s, u64 e)
{
u64 len, offset;
if (s < start || s >= end)
return 0;
offset = (s - start) + pgoff;
len = e < end ? e - s : end - s;
return kcore_copy_info__addnew(kci, s, len, offset) ? 0 : -1;
}
static int kcore_copy__read_map(u64 start, u64 len, u64 pgoff, void *data)
{
struct kcore_copy_info *kci = data;
u64 end = start + len;
struct sym_data *sdat;
if (kcore_copy__map(kci, start, end, pgoff, kci->stext, kci->etext))
return -1;
if (kcore_copy__map(kci, start, end, pgoff, kci->first_module,
kci->last_module_symbol))
return -1;
list_for_each_entry(sdat, &kci->syms, node) {
u64 s = round_down(sdat->addr, page_size);
if (kcore_copy__map(kci, start, end, pgoff, s, s + len))
return -1;
}
return 0;
}
static int kcore_copy__read_maps(struct kcore_copy_info *kci, Elf *elf)
{
if (elf_read_maps(elf, true, kcore_copy__read_map, kci) < 0)
return -1;
return 0;
}
static void kcore_copy__find_remaps(struct kcore_copy_info *kci)
{
struct phdr_data *p, *k = NULL;
u64 kend;
if (!kci->stext)
return;
/* Find phdr that corresponds to the kernel map (contains stext) */
kcore_copy__for_each_phdr(kci, p) {
u64 pend = p->addr + p->len - 1;
if (p->addr <= kci->stext && pend >= kci->stext) {
k = p;
break;
}
}
if (!k)
return;
kend = k->offset + k->len;
/* Find phdrs that remap the kernel */
kcore_copy__for_each_phdr(kci, p) {
u64 pend = p->offset + p->len;
if (p == k)
continue;
if (p->offset >= k->offset && pend <= kend)
p->remaps = k;
}
}
static void kcore_copy__layout(struct kcore_copy_info *kci)
{
struct phdr_data *p;
off_t rel = 0;
kcore_copy__find_remaps(kci);
kcore_copy__for_each_phdr(kci, p) {
if (!p->remaps) {
p->rel = rel;
rel += p->len;
}
kci->phnum += 1;
}
kcore_copy__for_each_phdr(kci, p) {
struct phdr_data *k = p->remaps;
if (k)
p->rel = p->offset - k->offset + k->rel;
}
}
static int kcore_copy__calc_maps(struct kcore_copy_info *kci, const char *dir,
Elf *elf)
{
if (kcore_copy__parse_kallsyms(kci, dir))
return -1;
if (kcore_copy__parse_modules(kci, dir))
return -1;
if (kci->stext)
kci->stext = round_down(kci->stext, page_size);
else
kci->stext = round_down(kci->first_symbol, page_size);
if (kci->etext) {
kci->etext = round_up(kci->etext, page_size);
} else if (kci->last_symbol) {
kci->etext = round_up(kci->last_symbol, page_size);
kci->etext += page_size;
}
if (kci->first_module_symbol &&
(!kci->first_module || kci->first_module_symbol < kci->first_module))
kci->first_module = kci->first_module_symbol;
kci->first_module = round_down(kci->first_module, page_size);
if (kci->last_module_symbol) {
kci->last_module_symbol = round_up(kci->last_module_symbol,
page_size);
kci->last_module_symbol += page_size;
}
if (!kci->stext || !kci->etext)
return -1;
if (kci->first_module && !kci->last_module_symbol)
return -1;
if (kcore_copy__read_maps(kci, elf))
return -1;
kcore_copy__layout(kci);
return 0;
}
static int kcore_copy__copy_file(const char *from_dir, const char *to_dir,
const char *name)
{
char from_filename[PATH_MAX];
char to_filename[PATH_MAX];
scnprintf(from_filename, PATH_MAX, "%s/%s", from_dir, name);
scnprintf(to_filename, PATH_MAX, "%s/%s", to_dir, name);
return copyfile_mode(from_filename, to_filename, 0400);
}
static int kcore_copy__unlink(const char *dir, const char *name)
{
char filename[PATH_MAX];
scnprintf(filename, PATH_MAX, "%s/%s", dir, name);
return unlink(filename);
}
static int kcore_copy__compare_fds(int from, int to)
{
char *buf_from;
char *buf_to;
ssize_t ret;
size_t len;
int err = -1;
buf_from = malloc(page_size);
buf_to = malloc(page_size);
if (!buf_from || !buf_to)
goto out;
while (1) {
/* Use read because mmap won't work on proc files */
ret = read(from, buf_from, page_size);
if (ret < 0)
goto out;
if (!ret)
break;
len = ret;
if (readn(to, buf_to, len) != (int)len)
goto out;
if (memcmp(buf_from, buf_to, len))
goto out;
}
err = 0;
out:
free(buf_to);
free(buf_from);
return err;
}
static int kcore_copy__compare_files(const char *from_filename,
const char *to_filename)
{
int from, to, err = -1;
from = open(from_filename, O_RDONLY);
if (from < 0)
return -1;
to = open(to_filename, O_RDONLY);
if (to < 0)
goto out_close_from;
err = kcore_copy__compare_fds(from, to);
close(to);
out_close_from:
close(from);
return err;
}
static int kcore_copy__compare_file(const char *from_dir, const char *to_dir,
const char *name)
{
char from_filename[PATH_MAX];
char to_filename[PATH_MAX];
scnprintf(from_filename, PATH_MAX, "%s/%s", from_dir, name);
scnprintf(to_filename, PATH_MAX, "%s/%s", to_dir, name);
return kcore_copy__compare_files(from_filename, to_filename);
}
/**
* kcore_copy - copy kallsyms, modules and kcore from one directory to another.
* @from_dir: from directory
* @to_dir: to directory
*
* This function copies kallsyms, modules and kcore files from one directory to
* another. kallsyms and modules are copied entirely. Only code segments are
* copied from kcore. It is assumed that two segments suffice: one for the
* kernel proper and one for all the modules. The code segments are determined
* from kallsyms and modules files. The kernel map starts at _stext or the
* lowest function symbol, and ends at _etext or the highest function symbol.
* The module map starts at the lowest module address and ends at the highest
* module symbol. Start addresses are rounded down to the nearest page. End
* addresses are rounded up to the nearest page. An extra page is added to the
* highest kernel symbol and highest module symbol to, hopefully, encompass that
* symbol too. Because it contains only code sections, the resulting kcore is
* unusual. One significant peculiarity is that the mapping (start -> pgoff)
* is not the same for the kernel map and the modules map. That happens because
* the data is copied adjacently whereas the original kcore has gaps. Finally,
* kallsyms file is compared with its copy to check that modules have not been
* loaded or unloaded while the copies were taking place.
*
* Return: %0 on success, %-1 on failure.
*/
int kcore_copy(const char *from_dir, const char *to_dir)
{
struct kcore kcore;
struct kcore extract;
int idx = 0, err = -1;
off_t offset, sz;
struct kcore_copy_info kci = { .stext = 0, };
char kcore_filename[PATH_MAX];
char extract_filename[PATH_MAX];
struct phdr_data *p;
INIT_LIST_HEAD(&kci.phdrs);
INIT_LIST_HEAD(&kci.syms);
if (kcore_copy__copy_file(from_dir, to_dir, "kallsyms"))
return -1;
if (kcore_copy__copy_file(from_dir, to_dir, "modules"))
goto out_unlink_kallsyms;
scnprintf(kcore_filename, PATH_MAX, "%s/kcore", from_dir);
scnprintf(extract_filename, PATH_MAX, "%s/kcore", to_dir);
if (kcore__open(&kcore, kcore_filename))
goto out_unlink_modules;
if (kcore_copy__calc_maps(&kci, from_dir, kcore.elf))
goto out_kcore_close;
if (kcore__init(&extract, extract_filename, kcore.elfclass, false))
goto out_kcore_close;
if (kcore__copy_hdr(&kcore, &extract, kci.phnum))
goto out_extract_close;
offset = gelf_fsize(extract.elf, ELF_T_EHDR, 1, EV_CURRENT) +
gelf_fsize(extract.elf, ELF_T_PHDR, kci.phnum, EV_CURRENT);
offset = round_up(offset, page_size);
kcore_copy__for_each_phdr(&kci, p) {
off_t offs = p->rel + offset;
if (kcore__add_phdr(&extract, idx++, offs, p->addr, p->len))
goto out_extract_close;
}
sz = kcore__write(&extract);
if (sz < 0 || sz > offset)
goto out_extract_close;
kcore_copy__for_each_phdr(&kci, p) {
off_t offs = p->rel + offset;
if (p->remaps)
continue;
if (copy_bytes(kcore.fd, p->offset, extract.fd, offs, p->len))
goto out_extract_close;
}
if (kcore_copy__compare_file(from_dir, to_dir, "kallsyms"))
goto out_extract_close;
err = 0;
out_extract_close:
kcore__close(&extract);
if (err)
unlink(extract_filename);
out_kcore_close:
kcore__close(&kcore);
out_unlink_modules:
if (err)
kcore_copy__unlink(to_dir, "modules");
out_unlink_kallsyms:
if (err)
kcore_copy__unlink(to_dir, "kallsyms");
kcore_copy__free_phdrs(&kci);
kcore_copy__free_syms(&kci);
return err;
}
int kcore_extract__create(struct kcore_extract *kce)
{
struct kcore kcore;
struct kcore extract;
size_t count = 1;
int idx = 0, err = -1;
off_t offset = page_size, sz;
if (kcore__open(&kcore, kce->kcore_filename))
return -1;
strcpy(kce->extract_filename, PERF_KCORE_EXTRACT);
if (kcore__init(&extract, kce->extract_filename, kcore.elfclass, true))
goto out_kcore_close;
if (kcore__copy_hdr(&kcore, &extract, count))
goto out_extract_close;
if (kcore__add_phdr(&extract, idx, offset, kce->addr, kce->len))
goto out_extract_close;
sz = kcore__write(&extract);
if (sz < 0 || sz > offset)
goto out_extract_close;
if (copy_bytes(kcore.fd, kce->offs, extract.fd, offset, kce->len))
goto out_extract_close;
err = 0;
out_extract_close:
kcore__close(&extract);
if (err)
unlink(kce->extract_filename);
out_kcore_close:
kcore__close(&kcore);
return err;
}
void kcore_extract__delete(struct kcore_extract *kce)
{
unlink(kce->extract_filename);
}
#ifdef HAVE_GELF_GETNOTE_SUPPORT
static void sdt_adjust_loc(struct sdt_note *tmp, GElf_Addr base_off)
{
if (!base_off)
return;
if (tmp->bit32)
tmp->addr.a32[SDT_NOTE_IDX_LOC] =
tmp->addr.a32[SDT_NOTE_IDX_LOC] + base_off -
tmp->addr.a32[SDT_NOTE_IDX_BASE];
else
tmp->addr.a64[SDT_NOTE_IDX_LOC] =
tmp->addr.a64[SDT_NOTE_IDX_LOC] + base_off -
tmp->addr.a64[SDT_NOTE_IDX_BASE];
}
static void sdt_adjust_refctr(struct sdt_note *tmp, GElf_Addr base_addr,
GElf_Addr base_off)
{
if (!base_off)
return;
if (tmp->bit32 && tmp->addr.a32[SDT_NOTE_IDX_REFCTR])
tmp->addr.a32[SDT_NOTE_IDX_REFCTR] -= (base_addr - base_off);
else if (tmp->addr.a64[SDT_NOTE_IDX_REFCTR])
tmp->addr.a64[SDT_NOTE_IDX_REFCTR] -= (base_addr - base_off);
}
/**
* populate_sdt_note : Parse raw data and identify SDT note
* @elf: elf of the opened file
* @data: raw data of a section with description offset applied
* @len: note description size
* @type: type of the note
* @sdt_notes: List to add the SDT note
*
* Responsible for parsing the @data in section .note.stapsdt in @elf and
* if its an SDT note, it appends to @sdt_notes list.
*/
static int populate_sdt_note(Elf **elf, const char *data, size_t len,
struct list_head *sdt_notes)
{
const char *provider, *name, *args;
struct sdt_note *tmp = NULL;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
int ret = -EINVAL;
union {
Elf64_Addr a64[NR_ADDR];
Elf32_Addr a32[NR_ADDR];
} buf;
Elf_Data dst = {
.d_buf = &buf, .d_type = ELF_T_ADDR, .d_version = EV_CURRENT,
.d_size = gelf_fsize((*elf), ELF_T_ADDR, NR_ADDR, EV_CURRENT),
.d_off = 0, .d_align = 0
};
Elf_Data src = {
.d_buf = (void *) data, .d_type = ELF_T_ADDR,
.d_version = EV_CURRENT, .d_size = dst.d_size, .d_off = 0,
.d_align = 0
};
tmp = (struct sdt_note *)calloc(1, sizeof(struct sdt_note));
if (!tmp) {
ret = -ENOMEM;
goto out_err;
}
INIT_LIST_HEAD(&tmp->note_list);
if (len < dst.d_size + 3)
goto out_free_note;
/* Translation from file representation to memory representation */
if (gelf_xlatetom(*elf, &dst, &src,
elf_getident(*elf, NULL)[EI_DATA]) == NULL) {
pr_err("gelf_xlatetom : %s\n", elf_errmsg(-1));
goto out_free_note;
}
/* Populate the fields of sdt_note */
provider = data + dst.d_size;
name = (const char *)memchr(provider, '\0', data + len - provider);
if (name++ == NULL)
goto out_free_note;
tmp->provider = strdup(provider);
if (!tmp->provider) {
ret = -ENOMEM;
goto out_free_note;
}
tmp->name = strdup(name);
if (!tmp->name) {
ret = -ENOMEM;
goto out_free_prov;
}
args = memchr(name, '\0', data + len - name);
/*
* There is no argument if:
* - We reached the end of the note;
* - There is not enough room to hold a potential string;
* - The argument string is empty or just contains ':'.
*/
if (args == NULL || data + len - args < 2 ||
args[1] == ':' || args[1] == '\0')
tmp->args = NULL;
else {
tmp->args = strdup(++args);
if (!tmp->args) {
ret = -ENOMEM;
goto out_free_name;
}
}
if (gelf_getclass(*elf) == ELFCLASS32) {
memcpy(&tmp->addr, &buf, 3 * sizeof(Elf32_Addr));
tmp->bit32 = true;
} else {
memcpy(&tmp->addr, &buf, 3 * sizeof(Elf64_Addr));
tmp->bit32 = false;
}
if (!gelf_getehdr(*elf, &ehdr)) {
pr_debug("%s : cannot get elf header.\n", __func__);
ret = -EBADF;
goto out_free_args;
}
/* Adjust the prelink effect :
* Find out the .stapsdt.base section.
* This scn will help us to handle prelinking (if present).
* Compare the retrieved file offset of the base section with the
* base address in the description of the SDT note. If its different,
* then accordingly, adjust the note location.
*/
if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_BASE_SCN, NULL))
sdt_adjust_loc(tmp, shdr.sh_offset);
/* Adjust reference counter offset */
if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_PROBES_SCN, NULL))
sdt_adjust_refctr(tmp, shdr.sh_addr, shdr.sh_offset);
list_add_tail(&tmp->note_list, sdt_notes);
return 0;
out_free_args:
zfree(&tmp->args);
out_free_name:
zfree(&tmp->name);
out_free_prov:
zfree(&tmp->provider);
out_free_note:
free(tmp);
out_err:
return ret;
}
/**
* construct_sdt_notes_list : constructs a list of SDT notes
* @elf : elf to look into
* @sdt_notes : empty list_head
*
* Scans the sections in 'elf' for the section
* .note.stapsdt. It, then calls populate_sdt_note to find
* out the SDT events and populates the 'sdt_notes'.
*/
static int construct_sdt_notes_list(Elf *elf, struct list_head *sdt_notes)
{
GElf_Ehdr ehdr;
Elf_Scn *scn = NULL;
Elf_Data *data;
GElf_Shdr shdr;
size_t shstrndx, next;
GElf_Nhdr nhdr;
size_t name_off, desc_off, offset;
int ret = 0;
if (gelf_getehdr(elf, &ehdr) == NULL) {
ret = -EBADF;
goto out_ret;
}
if (elf_getshdrstrndx(elf, &shstrndx) != 0) {
ret = -EBADF;
goto out_ret;
}
/* Look for the required section */
scn = elf_section_by_name(elf, &ehdr, &shdr, SDT_NOTE_SCN, NULL);
if (!scn) {
ret = -ENOENT;
goto out_ret;
}
if ((shdr.sh_type != SHT_NOTE) || (shdr.sh_flags & SHF_ALLOC)) {
ret = -ENOENT;
goto out_ret;
}
data = elf_getdata(scn, NULL);
/* Get the SDT notes */
for (offset = 0; (next = gelf_getnote(data, offset, &nhdr, &name_off,
&desc_off)) > 0; offset = next) {
if (nhdr.n_namesz == sizeof(SDT_NOTE_NAME) &&
!memcmp(data->d_buf + name_off, SDT_NOTE_NAME,
sizeof(SDT_NOTE_NAME))) {
/* Check the type of the note */
if (nhdr.n_type != SDT_NOTE_TYPE)
goto out_ret;
ret = populate_sdt_note(&elf, ((data->d_buf) + desc_off),
nhdr.n_descsz, sdt_notes);
if (ret < 0)
goto out_ret;
}
}
if (list_empty(sdt_notes))
ret = -ENOENT;
out_ret:
return ret;
}
/**
* get_sdt_note_list : Wrapper to construct a list of sdt notes
* @head : empty list_head
* @target : file to find SDT notes from
*
* This opens the file, initializes
* the ELF and then calls construct_sdt_notes_list.
*/
int get_sdt_note_list(struct list_head *head, const char *target)
{
Elf *elf;
int fd, ret;
fd = open(target, O_RDONLY);
if (fd < 0)
return -EBADF;
elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
if (!elf) {
ret = -EBADF;
goto out_close;
}
ret = construct_sdt_notes_list(elf, head);
elf_end(elf);
out_close:
close(fd);
return ret;
}
/**
* cleanup_sdt_note_list : free the sdt notes' list
* @sdt_notes: sdt notes' list
*
* Free up the SDT notes in @sdt_notes.
* Returns the number of SDT notes free'd.
*/
int cleanup_sdt_note_list(struct list_head *sdt_notes)
{
struct sdt_note *tmp, *pos;
int nr_free = 0;
list_for_each_entry_safe(pos, tmp, sdt_notes, note_list) {
list_del_init(&pos->note_list);
zfree(&pos->args);
zfree(&pos->name);
zfree(&pos->provider);
free(pos);
nr_free++;
}
return nr_free;
}
/**
* sdt_notes__get_count: Counts the number of sdt events
* @start: list_head to sdt_notes list
*
* Returns the number of SDT notes in a list
*/
int sdt_notes__get_count(struct list_head *start)
{
struct sdt_note *sdt_ptr;
int count = 0;
list_for_each_entry(sdt_ptr, start, note_list)
count++;
return count;
}
#endif
void symbol__elf_init(void)
{
elf_version(EV_CURRENT);
}