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Copy pathstack.c
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515 lines (463 loc) · 14.1 KB
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/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/pfn.h>
#include <linux/kallsyms.h>
#include <linux/stacktrace.h>
#include <linux/uaccess.h>
#include <linux/mmzone.h>
#include <linux/dcache.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <asm/backtrace.h>
#include <asm/page.h>
#include <asm/ucontext.h>
#include <asm/switch_to.h>
#include <asm/sigframe.h>
#include <asm/stack.h>
#include <asm/vdso.h>
#include <arch/abi.h>
#include <arch/interrupts.h>
#define KBT_ONGOING 0 /* Backtrace still ongoing */
#define KBT_DONE 1 /* Backtrace cleanly completed */
#define KBT_RUNNING 2 /* Can't run backtrace on a running task */
#define KBT_LOOP 3 /* Backtrace entered a loop */
/* Is address on the specified kernel stack? */
static int in_kernel_stack(struct KBacktraceIterator *kbt, unsigned long sp)
{
ulong kstack_base = (ulong) kbt->task->stack;
if (kstack_base == 0) /* corrupt task pointer; just follow stack... */
return sp >= PAGE_OFFSET && sp < (unsigned long)high_memory;
return sp >= kstack_base && sp < kstack_base + THREAD_SIZE;
}
/* Callback for backtracer; basically a glorified memcpy */
static bool read_memory_func(void *result, unsigned long address,
unsigned int size, void *vkbt)
{
int retval;
struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;
if (address == 0)
return 0;
if (__kernel_text_address(address)) {
/* OK to read kernel code. */
} else if (address >= PAGE_OFFSET) {
/* We only tolerate kernel-space reads of this task's stack */
if (!in_kernel_stack(kbt, address))
return 0;
} else if (!kbt->is_current) {
return 0; /* can't read from other user address spaces */
}
pagefault_disable();
retval = __copy_from_user_inatomic(result,
(void __user __force *)address,
size);
pagefault_enable();
return (retval == 0);
}
/* Return a pt_regs pointer for a valid fault handler frame */
static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
{
const char *fault = NULL; /* happy compiler */
char fault_buf[64];
unsigned long sp = kbt->it.sp;
struct pt_regs *p;
if (sp % sizeof(long) != 0)
return NULL;
if (!in_kernel_stack(kbt, sp))
return NULL;
if (!in_kernel_stack(kbt, sp + C_ABI_SAVE_AREA_SIZE + PTREGS_SIZE-1))
return NULL;
p = (struct pt_regs *)(sp + C_ABI_SAVE_AREA_SIZE);
if (p->faultnum == INT_SWINT_1 || p->faultnum == INT_SWINT_1_SIGRETURN)
fault = "syscall";
else {
if (kbt->verbose) { /* else we aren't going to use it */
snprintf(fault_buf, sizeof(fault_buf),
"interrupt %ld", p->faultnum);
fault = fault_buf;
}
}
if (EX1_PL(p->ex1) == KERNEL_PL &&
__kernel_text_address(p->pc) &&
in_kernel_stack(kbt, p->sp) &&
p->sp >= sp) {
if (kbt->verbose)
pr_err(" <%s while in kernel mode>\n", fault);
} else if (user_mode(p) &&
p->sp < PAGE_OFFSET && p->sp != 0) {
if (kbt->verbose)
pr_err(" <%s while in user mode>\n", fault);
} else {
if (kbt->verbose)
pr_err(" (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n",
p->pc, p->sp, p->ex1);
return NULL;
}
if (kbt->profile && ((1ULL << p->faultnum) & QUEUED_INTERRUPTS) != 0)
return NULL;
return p;
}
/* Is the pc pointing to a sigreturn trampoline? */
static int is_sigreturn(unsigned long pc)
{
return current->mm && (pc == VDSO_SYM(&__vdso_rt_sigreturn));
}
/* Return a pt_regs pointer for a valid signal handler frame */
static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt,
struct rt_sigframe* kframe)
{
BacktraceIterator *b = &kbt->it;
if (is_sigreturn(b->pc) && b->sp < PAGE_OFFSET &&
b->sp % sizeof(long) == 0) {
int retval;
pagefault_disable();
retval = __copy_from_user_inatomic(
kframe, (void __user __force *)b->sp,
sizeof(*kframe));
pagefault_enable();
if (retval != 0 ||
(unsigned int)(kframe->info.si_signo) >= _NSIG)
return NULL;
if (kbt->verbose) {
pr_err(" <received signal %d>\n",
kframe->info.si_signo);
}
return (struct pt_regs *)&kframe->uc.uc_mcontext;
}
return NULL;
}
static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
{
return is_sigreturn(kbt->it.pc);
}
static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt)
{
struct pt_regs *p;
struct rt_sigframe kframe;
p = valid_fault_handler(kbt);
if (p == NULL)
p = valid_sigframe(kbt, &kframe);
if (p == NULL)
return 0;
backtrace_init(&kbt->it, read_memory_func, kbt,
p->pc, p->lr, p->sp, p->regs[52]);
kbt->new_context = 1;
return 1;
}
/* Find a frame that isn't a sigreturn, if there is one. */
static int KBacktraceIterator_next_item_inclusive(
struct KBacktraceIterator *kbt)
{
for (;;) {
do {
if (!KBacktraceIterator_is_sigreturn(kbt))
return KBT_ONGOING;
} while (backtrace_next(&kbt->it));
if (!KBacktraceIterator_restart(kbt))
return KBT_DONE;
}
}
/*
* If the current sp is on a page different than what we recorded
* as the top-of-kernel-stack last time we context switched, we have
* probably blown the stack, and nothing is going to work out well.
* If we can at least get out a warning, that may help the debug,
* though we probably won't be able to backtrace into the code that
* actually did the recursive damage.
*/
static void validate_stack(struct pt_regs *regs)
{
int cpu = raw_smp_processor_id();
unsigned long ksp0 = get_current_ksp0();
unsigned long ksp0_base = ksp0 & -THREAD_SIZE;
unsigned long sp = stack_pointer;
if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) {
pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx underrun!\n"
" sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
}
else if (sp < ksp0_base + sizeof(struct thread_info)) {
pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx overrun!\n"
" sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
}
}
void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
struct task_struct *t, struct pt_regs *regs)
{
unsigned long pc, lr, sp, r52;
int is_current;
/*
* Set up callback information. We grab the kernel stack base
* so we will allow reads of that address range.
*/
is_current = (t == NULL || t == current);
kbt->is_current = is_current;
if (is_current)
t = validate_current();
kbt->task = t;
kbt->verbose = 0; /* override in caller if desired */
kbt->profile = 0; /* override in caller if desired */
kbt->end = KBT_ONGOING;
kbt->new_context = 1;
if (is_current)
validate_stack(regs);
if (regs == NULL) {
if (is_current || t->state == TASK_RUNNING) {
/* Can't do this; we need registers */
kbt->end = KBT_RUNNING;
return;
}
pc = get_switch_to_pc();
lr = t->thread.pc;
sp = t->thread.ksp;
r52 = 0;
} else {
pc = regs->pc;
lr = regs->lr;
sp = regs->sp;
r52 = regs->regs[52];
}
backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52);
kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
}
EXPORT_SYMBOL(KBacktraceIterator_init);
int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
{
return kbt->end != KBT_ONGOING;
}
EXPORT_SYMBOL(KBacktraceIterator_end);
void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
{
unsigned long old_pc = kbt->it.pc, old_sp = kbt->it.sp;
kbt->new_context = 0;
if (!backtrace_next(&kbt->it) && !KBacktraceIterator_restart(kbt)) {
kbt->end = KBT_DONE;
return;
}
kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
if (old_pc == kbt->it.pc && old_sp == kbt->it.sp) {
/* Trapped in a loop; give up. */
kbt->end = KBT_LOOP;
}
}
EXPORT_SYMBOL(KBacktraceIterator_next);
static void describe_addr(struct KBacktraceIterator *kbt,
unsigned long address,
int have_mmap_sem, char *buf, size_t bufsize)
{
struct vm_area_struct *vma;
size_t namelen, remaining;
unsigned long size, offset, adjust;
char *p, *modname;
const char *name;
int rc;
/*
* Look one byte back for every caller frame (i.e. those that
* aren't a new context) so we look up symbol data for the
* call itself, not the following instruction, which may be on
* a different line (or in a different function).
*/
adjust = !kbt->new_context;
address -= adjust;
if (address >= PAGE_OFFSET) {
/* Handle kernel symbols. */
BUG_ON(bufsize < KSYM_NAME_LEN);
name = kallsyms_lookup(address, &size, &offset,
&modname, buf);
if (name == NULL) {
buf[0] = '\0';
return;
}
namelen = strlen(buf);
remaining = (bufsize - 1) - namelen;
p = buf + namelen;
rc = snprintf(p, remaining, "+%#lx/%#lx ",
offset + adjust, size);
if (modname && rc < remaining)
snprintf(p + rc, remaining - rc, "[%s] ", modname);
buf[bufsize-1] = '\0';
return;
}
/* If we don't have the mmap_sem, we can't show any more info. */
buf[0] = '\0';
if (!have_mmap_sem)
return;
/* Find vma info. */
vma = find_vma(kbt->task->mm, address);
if (vma == NULL || address < vma->vm_start) {
snprintf(buf, bufsize, "[unmapped address] ");
return;
}
if (vma->vm_file) {
p = d_path(&vma->vm_file->f_path, buf, bufsize);
if (IS_ERR(p))
p = "?";
name = kbasename(p);
} else {
name = "anon";
}
/* Generate a string description of the vma info. */
namelen = strlen(name);
remaining = (bufsize - 1) - namelen;
memmove(buf, name, namelen);
snprintf(buf + namelen, remaining, "[%lx+%lx] ",
vma->vm_start, vma->vm_end - vma->vm_start);
}
/*
* Avoid possible crash recursion during backtrace. If it happens, it
* makes it easy to lose the actual root cause of the failure, so we
* put a simple guard on all the backtrace loops.
*/
static bool start_backtrace(void)
{
if (current->thread.in_backtrace) {
pr_err("Backtrace requested while in backtrace!\n");
return false;
}
current->thread.in_backtrace = true;
return true;
}
static void end_backtrace(void)
{
current->thread.in_backtrace = false;
}
/*
* This method wraps the backtracer's more generic support.
* It is only invoked from the architecture-specific code; show_stack()
* and dump_stack() (in entry.S) are architecture-independent entry points.
*/
void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
{
int i;
int have_mmap_sem = 0;
if (!start_backtrace())
return;
if (headers) {
/*
* Add a blank line since if we are called from panic(),
* then bust_spinlocks() spit out a space in front of us
* and it will mess up our KERN_ERR.
*/
pr_err("Starting stack dump of tid %d, pid %d (%s) on cpu %d at cycle %lld\n",
kbt->task->pid, kbt->task->tgid, kbt->task->comm,
raw_smp_processor_id(), get_cycles());
}
kbt->verbose = 1;
i = 0;
for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) {
char namebuf[KSYM_NAME_LEN+100];
unsigned long address = kbt->it.pc;
/* Try to acquire the mmap_sem as we pass into userspace. */
if (address < PAGE_OFFSET && !have_mmap_sem && kbt->task->mm)
have_mmap_sem =
down_read_trylock(&kbt->task->mm->mmap_sem);
describe_addr(kbt, address, have_mmap_sem,
namebuf, sizeof(namebuf));
pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n",
i++, address, namebuf, (unsigned long)(kbt->it.sp));
if (i >= 100) {
pr_err("Stack dump truncated (%d frames)\n", i);
break;
}
}
if (kbt->end == KBT_LOOP)
pr_err("Stack dump stopped; next frame identical to this one\n");
if (headers)
pr_err("Stack dump complete\n");
if (have_mmap_sem)
up_read(&kbt->task->mm->mmap_sem);
end_backtrace();
}
EXPORT_SYMBOL(tile_show_stack);
/* This is called from show_regs() and _dump_stack() */
void dump_stack_regs(struct pt_regs *regs)
{
struct KBacktraceIterator kbt;
KBacktraceIterator_init(&kbt, NULL, regs);
tile_show_stack(&kbt, 1);
}
EXPORT_SYMBOL(dump_stack_regs);
static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs,
ulong pc, ulong lr, ulong sp, ulong r52)
{
memset(regs, 0, sizeof(struct pt_regs));
regs->pc = pc;
regs->lr = lr;
regs->sp = sp;
regs->regs[52] = r52;
return regs;
}
/* This is called from dump_stack() and just converts to pt_regs */
void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
{
struct pt_regs regs;
dump_stack_regs(regs_to_pt_regs(®s, pc, lr, sp, r52));
}
/* This is called from KBacktraceIterator_init_current() */
void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc,
ulong lr, ulong sp, ulong r52)
{
struct pt_regs regs;
KBacktraceIterator_init(kbt, NULL,
regs_to_pt_regs(®s, pc, lr, sp, r52));
}
/* This is called only from kernel/sched/core.c, with esp == NULL */
void show_stack(struct task_struct *task, unsigned long *esp)
{
struct KBacktraceIterator kbt;
if (task == NULL || task == current)
KBacktraceIterator_init_current(&kbt);
else
KBacktraceIterator_init(&kbt, task, NULL);
tile_show_stack(&kbt, 0);
}
#ifdef CONFIG_STACKTRACE
/* Support generic Linux stack API too */
void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
{
struct KBacktraceIterator kbt;
int skip = trace->skip;
int i = 0;
if (!start_backtrace())
goto done;
if (task == NULL || task == current)
KBacktraceIterator_init_current(&kbt);
else
KBacktraceIterator_init(&kbt, task, NULL);
for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) {
if (skip) {
--skip;
continue;
}
if (i >= trace->max_entries || kbt.it.pc < PAGE_OFFSET)
break;
trace->entries[i++] = kbt.it.pc;
}
end_backtrace();
done:
trace->nr_entries = i;
}
EXPORT_SYMBOL(save_stack_trace_tsk);
void save_stack_trace(struct stack_trace *trace)
{
save_stack_trace_tsk(NULL, trace);
}
EXPORT_SYMBOL_GPL(save_stack_trace);
#endif
/* In entry.S */
EXPORT_SYMBOL(KBacktraceIterator_init_current);
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