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linux-zen-server/arch/xtensa/kernel/traps.c

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/*
* arch/xtensa/kernel/traps.c
*
* Exception handling.
*
* Derived from code with the following copyrights:
* Copyright (C) 1994 - 1999 by Ralf Baechle
* Modified for R3000 by Paul M. Antoine, 1995, 1996
* Complete output from die() by Ulf Carlsson, 1998
* Copyright (C) 1999 Silicon Graphics, Inc.
*
* Essentially rewritten for the Xtensa architecture port.
*
* Copyright (C) 2001 - 2013 Tensilica Inc.
*
* Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
* Chris Zankel <chris@zankel.net>
* Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca>
* Kevin Chea
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/kernel.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/kallsyms.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <linux/ratelimit.h>
#include <linux/pgtable.h>
#include <asm/stacktrace.h>
#include <asm/ptrace.h>
#include <asm/timex.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <asm/traps.h>
#include <asm/hw_breakpoint.h>
/*
* Machine specific interrupt handlers
*/
static void do_illegal_instruction(struct pt_regs *regs);
static void do_div0(struct pt_regs *regs);
static void do_interrupt(struct pt_regs *regs);
#if XTENSA_FAKE_NMI
static void do_nmi(struct pt_regs *regs);
#endif
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
static void do_unaligned_user(struct pt_regs *regs);
#endif
static void do_multihit(struct pt_regs *regs);
#if XTENSA_HAVE_COPROCESSORS
static void do_coprocessor(struct pt_regs *regs);
#endif
static void do_debug(struct pt_regs *regs);
/*
* The vector table must be preceded by a save area (which
* implies it must be in RAM, unless one places RAM immediately
* before a ROM and puts the vector at the start of the ROM (!))
*/
#define KRNL 0x01
#define USER 0x02
#define COPROCESSOR(x) \
{ EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER|KRNL, fast_coprocessor },\
{ EXCCAUSE_COPROCESSOR ## x ## _DISABLED, 0, do_coprocessor }
typedef struct {
int cause;
int fast;
void* handler;
} dispatch_init_table_t;
static dispatch_init_table_t __initdata dispatch_init_table[] = {
#ifdef CONFIG_USER_ABI_CALL0_PROBE
{ EXCCAUSE_ILLEGAL_INSTRUCTION, USER, fast_illegal_instruction_user },
#endif
{ EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction},
{ EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user },
{ EXCCAUSE_SYSTEM_CALL, 0, system_call },
/* EXCCAUSE_INSTRUCTION_FETCH unhandled */
/* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
{ EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
#ifdef SUPPORT_WINDOWED
{ EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
#endif
{ EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0, do_div0 },
/* EXCCAUSE_PRIVILEGED unhandled */
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
#ifdef CONFIG_XTENSA_UNALIGNED_USER
{ EXCCAUSE_UNALIGNED, USER, fast_unaligned },
#endif
{ EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
{ EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
#endif
#ifdef CONFIG_MMU
{ EXCCAUSE_ITLB_MISS, 0, do_page_fault },
{ EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss},
{ EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss},
{ EXCCAUSE_DTLB_MISS, 0, do_page_fault },
{ EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
#endif /* CONFIG_MMU */
#ifdef CONFIG_PFAULT
{ EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit },
{ EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault },
{ EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault },
{ EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit },
{ EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault },
{ EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault },
{ EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault },
#endif
/* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
#if XTENSA_HAVE_COPROCESSOR(0)
COPROCESSOR(0),
#endif
#if XTENSA_HAVE_COPROCESSOR(1)
COPROCESSOR(1),
#endif
#if XTENSA_HAVE_COPROCESSOR(2)
COPROCESSOR(2),
#endif
#if XTENSA_HAVE_COPROCESSOR(3)
COPROCESSOR(3),
#endif
#if XTENSA_HAVE_COPROCESSOR(4)
COPROCESSOR(4),
#endif
#if XTENSA_HAVE_COPROCESSOR(5)
COPROCESSOR(5),
#endif
#if XTENSA_HAVE_COPROCESSOR(6)
COPROCESSOR(6),
#endif
#if XTENSA_HAVE_COPROCESSOR(7)
COPROCESSOR(7),
#endif
#if XTENSA_FAKE_NMI
{ EXCCAUSE_MAPPED_NMI, 0, do_nmi },
#endif
{ EXCCAUSE_MAPPED_DEBUG, 0, do_debug },
{ -1, -1, 0 }
};
/* The exception table <exc_table> serves two functions:
* 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
* 2. it is a temporary memory buffer for the exception handlers.
*/
DEFINE_PER_CPU(struct exc_table, exc_table);
DEFINE_PER_CPU(struct debug_table, debug_table);
void die(const char*, struct pt_regs*, long);
static inline void
__die_if_kernel(const char *str, struct pt_regs *regs, long err)
{
if (!user_mode(regs))
die(str, regs, err);
}
/*
* Unhandled Exceptions. Kill user task or panic if in kernel space.
*/
void do_unhandled(struct pt_regs *regs)
{
__die_if_kernel("Caught unhandled exception - should not happen",
regs, SIGKILL);
/* If in user mode, send SIGILL signal to current process */
pr_info_ratelimited("Caught unhandled exception in '%s' "
"(pid = %d, pc = %#010lx) - should not happen\n"
"\tEXCCAUSE is %ld\n",
current->comm, task_pid_nr(current), regs->pc,
regs->exccause);
force_sig(SIGILL);
}
/*
* Multi-hit exception. This if fatal!
*/
static void do_multihit(struct pt_regs *regs)
{
die("Caught multihit exception", regs, SIGKILL);
}
/*
* IRQ handler.
*/
#if XTENSA_FAKE_NMI
#define IS_POW2(v) (((v) & ((v) - 1)) == 0)
#if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
#warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
#warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
static inline void check_valid_nmi(void)
{
unsigned intread = xtensa_get_sr(interrupt);
unsigned intenable = xtensa_get_sr(intenable);
BUG_ON(intread & intenable &
~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
BIT(XCHAL_PROFILING_INTERRUPT)));
}
#else
static inline void check_valid_nmi(void)
{
}
#endif
irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
DEFINE_PER_CPU(unsigned long, nmi_count);
static void do_nmi(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
nmi_enter();
++*this_cpu_ptr(&nmi_count);
check_valid_nmi();
xtensa_pmu_irq_handler(0, NULL);
nmi_exit();
set_irq_regs(old_regs);
}
#endif
static void do_interrupt(struct pt_regs *regs)
{
static const unsigned int_level_mask[] = {
0,
XCHAL_INTLEVEL1_MASK,
XCHAL_INTLEVEL2_MASK,
XCHAL_INTLEVEL3_MASK,
XCHAL_INTLEVEL4_MASK,
XCHAL_INTLEVEL5_MASK,
XCHAL_INTLEVEL6_MASK,
XCHAL_INTLEVEL7_MASK,
};
struct pt_regs *old_regs = set_irq_regs(regs);
unsigned unhandled = ~0u;
irq_enter();
for (;;) {
unsigned intread = xtensa_get_sr(interrupt);
unsigned intenable = xtensa_get_sr(intenable);
unsigned int_at_level = intread & intenable;
unsigned level;
for (level = LOCKLEVEL; level > 0; --level) {
if (int_at_level & int_level_mask[level]) {
int_at_level &= int_level_mask[level];
if (int_at_level & unhandled)
int_at_level &= unhandled;
else
unhandled |= int_level_mask[level];
break;
}
}
if (level == 0)
break;
/* clear lowest pending irq in the unhandled mask */
unhandled ^= (int_at_level & -int_at_level);
do_IRQ(__ffs(int_at_level), regs);
}
irq_exit();
set_irq_regs(old_regs);
}
static bool check_div0(struct pt_regs *regs)
{
static const u8 pattern[] = {'D', 'I', 'V', '0'};
const u8 *p;
u8 buf[5];
if (user_mode(regs)) {
if (copy_from_user(buf, (void __user *)regs->pc + 2, 5))
return false;
p = buf;
} else {
p = (const u8 *)regs->pc + 2;
}
return memcmp(p, pattern, sizeof(pattern)) == 0 ||
memcmp(p + 1, pattern, sizeof(pattern)) == 0;
}
/*
* Illegal instruction. Fatal if in kernel space.
*/
static void do_illegal_instruction(struct pt_regs *regs)
{
#ifdef CONFIG_USER_ABI_CALL0_PROBE
/*
* When call0 application encounters an illegal instruction fast
* exception handler will attempt to set PS.WOE and retry failing
* instruction.
* If we get here we know that that instruction is also illegal
* with PS.WOE set, so it's not related to the windowed option
* hence PS.WOE may be cleared.
*/
if (regs->pc == current_thread_info()->ps_woe_fix_addr)
regs->ps &= ~PS_WOE_MASK;
#endif
if (check_div0(regs)) {
do_div0(regs);
return;
}
__die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
/* If in user mode, send SIGILL signal to current process. */
pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
current->comm, task_pid_nr(current), regs->pc);
force_sig(SIGILL);
}
static void do_div0(struct pt_regs *regs)
{
__die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL);
force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc);
}
/*
* Handle unaligned memory accesses from user space. Kill task.
*
* If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
* accesses causes from user space.
*/
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
static void do_unaligned_user(struct pt_regs *regs)
{
__die_if_kernel("Unhandled unaligned exception in kernel",
regs, SIGKILL);
pr_info_ratelimited("Unaligned memory access to %08lx in '%s' "
"(pid = %d, pc = %#010lx)\n",
regs->excvaddr, current->comm,
task_pid_nr(current), regs->pc);
force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr);
}
#endif
#if XTENSA_HAVE_COPROCESSORS
static void do_coprocessor(struct pt_regs *regs)
{
coprocessor_flush_release_all(current_thread_info());
}
#endif
/* Handle debug events.
* When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
* preemption disabled to avoid rescheduling and keep mapping of hardware
* breakpoint structures to debug registers intact, so that
* DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
*/
static void do_debug(struct pt_regs *regs)
{
#ifdef CONFIG_HAVE_HW_BREAKPOINT
int ret = check_hw_breakpoint(regs);
preempt_enable();
if (ret == 0)
return;
#endif
__die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
/* If in user mode, send SIGTRAP signal to current process */
force_sig(SIGTRAP);
}
#define set_handler(type, cause, handler) \
do { \
unsigned int cpu; \
\
for_each_possible_cpu(cpu) \
per_cpu(exc_table, cpu).type[cause] = (handler);\
} while (0)
/* Set exception C handler - for temporary use when probing exceptions */
xtensa_exception_handler *
__init trap_set_handler(int cause, xtensa_exception_handler *handler)
{
void *previous = per_cpu(exc_table, 0).default_handler[cause];
set_handler(default_handler, cause, handler);
return previous;
}
static void trap_init_excsave(void)
{
xtensa_set_sr(this_cpu_ptr(&exc_table), excsave1);
}
static void trap_init_debug(void)
{
unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
__asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
:: "a"(debugsave));
}
/*
* Initialize dispatch tables.
*
* The exception vectors are stored compressed the __init section in the
* dispatch_init_table. This function initializes the following three tables
* from that compressed table:
* - fast user first dispatch table for user exceptions
* - fast kernel first dispatch table for kernel exceptions
* - default C-handler C-handler called by the default fast handler.
*
* See vectors.S for more details.
*/
void __init trap_init(void)
{
int i;
/* Setup default vectors. */
for (i = 0; i < EXCCAUSE_N; i++) {
set_handler(fast_user_handler, i, user_exception);
set_handler(fast_kernel_handler, i, kernel_exception);
set_handler(default_handler, i, do_unhandled);
}
/* Setup specific handlers. */
for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
int fast = dispatch_init_table[i].fast;
int cause = dispatch_init_table[i].cause;
void *handler = dispatch_init_table[i].handler;
if (fast == 0)
set_handler(default_handler, cause, handler);
if ((fast & USER) != 0)
set_handler(fast_user_handler, cause, handler);
if ((fast & KRNL) != 0)
set_handler(fast_kernel_handler, cause, handler);
}
/* Initialize EXCSAVE_1 to hold the address of the exception table. */
trap_init_excsave();
trap_init_debug();
}
#ifdef CONFIG_SMP
void secondary_trap_init(void)
{
trap_init_excsave();
trap_init_debug();
}
#endif
/*
* This function dumps the current valid window frame and other base registers.
*/
void show_regs(struct pt_regs * regs)
{
int i;
show_regs_print_info(KERN_DEFAULT);
for (i = 0; i < 16; i++) {
if ((i % 8) == 0)
pr_info("a%02d:", i);
pr_cont(" %08lx", regs->areg[i]);
}
pr_cont("\n");
pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
regs->pc, regs->ps, regs->depc, regs->excvaddr);
pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
regs->lbeg, regs->lend, regs->lcount, regs->sar);
if (user_mode(regs))
pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
regs->windowbase, regs->windowstart, regs->wmask,
regs->syscall);
}
static int show_trace_cb(struct stackframe *frame, void *data)
{
const char *loglvl = data;
if (kernel_text_address(frame->pc))
printk("%s [<%08lx>] %pB\n",
loglvl, frame->pc, (void *)frame->pc);
return 0;
}
static void show_trace(struct task_struct *task, unsigned long *sp,
const char *loglvl)
{
if (!sp)
sp = stack_pointer(task);
printk("%sCall Trace:\n", loglvl);
walk_stackframe(sp, show_trace_cb, (void *)loglvl);
}
#define STACK_DUMP_ENTRY_SIZE 4
#define STACK_DUMP_LINE_SIZE 32
static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
{
size_t len, off = 0;
if (!sp)
sp = stack_pointer(task);
len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE),
kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE);
printk("%sStack:\n", loglvl);
while (off < len) {
u8 line[STACK_DUMP_LINE_SIZE];
size_t line_len = len - off > STACK_DUMP_LINE_SIZE ?
STACK_DUMP_LINE_SIZE : len - off;
__memcpy(line, (u8 *)sp + off, line_len);
print_hex_dump(loglvl, " ", DUMP_PREFIX_NONE,
STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE,
line, line_len, false);
off += STACK_DUMP_LINE_SIZE;
}
show_trace(task, sp, loglvl);
}
DEFINE_SPINLOCK(die_lock);
void __noreturn die(const char * str, struct pt_regs * regs, long err)
{
static int die_counter;
const char *pr = "";
if (IS_ENABLED(CONFIG_PREEMPTION))
pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
console_verbose();
spin_lock_irq(&die_lock);
pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr);
show_regs(regs);
if (!user_mode(regs))
show_stack(NULL, (unsigned long *)regs->areg[1], KERN_INFO);
add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
spin_unlock_irq(&die_lock);
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
panic("Fatal exception");
make_task_dead(err);
}
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