2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
15 #include <linux/sched.h>
16 #include <linux/kernel.h>
17 #include <linux/kprobes.h>
18 #include <linux/module.h>
19 #include <linux/pfn.h>
20 #include <linux/kallsyms.h>
21 #include <linux/stacktrace.h>
22 #include <linux/uaccess.h>
23 #include <linux/mmzone.h>
24 #include <linux/dcache.h>
26 #include <linux/hardirq.h>
27 #include <linux/string.h>
28 #include <asm/backtrace.h>
30 #include <asm/ucontext.h>
31 #include <asm/switch_to.h>
32 #include <asm/sigframe.h>
33 #include <asm/stack.h>
36 #include <arch/interrupts.h>
38 #define KBT_ONGOING 0 /* Backtrace still ongoing */
39 #define KBT_DONE 1 /* Backtrace cleanly completed */
40 #define KBT_RUNNING 2 /* Can't run backtrace on a running task */
41 #define KBT_LOOP 3 /* Backtrace entered a loop */
43 /* Is address on the specified kernel stack? */
44 static int in_kernel_stack(struct KBacktraceIterator *kbt, unsigned long sp)
46 ulong kstack_base = (ulong) kbt->task->stack;
47 if (kstack_base == 0) /* corrupt task pointer; just follow stack... */
48 return sp >= PAGE_OFFSET && sp < (unsigned long)high_memory;
49 return sp >= kstack_base && sp < kstack_base + THREAD_SIZE;
52 /* Callback for backtracer; basically a glorified memcpy */
53 static bool read_memory_func(void *result, unsigned long address,
54 unsigned int size, void *vkbt)
57 struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;
61 if (__kernel_text_address(address)) {
62 /* OK to read kernel code. */
63 } else if (address >= PAGE_OFFSET) {
64 /* We only tolerate kernel-space reads of this task's stack */
65 if (!in_kernel_stack(kbt, address))
67 } else if (!kbt->is_current) {
68 return 0; /* can't read from other user address spaces */
71 retval = __copy_from_user_inatomic(result,
72 (void __user __force *)address,
78 /* Return a pt_regs pointer for a valid fault handler frame */
79 static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
82 unsigned long sp = kbt->it.sp;
85 if (sp % sizeof(long) != 0)
87 if (!in_kernel_stack(kbt, sp))
89 if (!in_kernel_stack(kbt, sp + C_ABI_SAVE_AREA_SIZE + PTREGS_SIZE-1))
91 p = (struct pt_regs *)(sp + C_ABI_SAVE_AREA_SIZE);
92 if (kbt->verbose) { /* else we aren't going to use it */
93 if (p->faultnum == INT_SWINT_1 ||
94 p->faultnum == INT_SWINT_1_SIGRETURN)
95 snprintf(fault, sizeof(fault),
96 "syscall %ld", p->regs[TREG_SYSCALL_NR]);
98 snprintf(fault, sizeof(fault),
99 "interrupt %ld", p->faultnum);
101 if (EX1_PL(p->ex1) == KERNEL_PL &&
102 __kernel_text_address(p->pc) &&
103 in_kernel_stack(kbt, p->sp) &&
106 pr_err(" <%s while in kernel mode>\n", fault);
107 } else if (user_mode(p) &&
108 p->sp < PAGE_OFFSET && p->sp != 0) {
110 pr_err(" <%s while in user mode>\n", fault);
112 if (kbt->verbose && (p->pc != 0 || p->sp != 0 || p->ex1 != 0))
113 pr_err(" (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n",
114 p->pc, p->sp, p->ex1);
117 if (kbt->profile && ((1ULL << p->faultnum) & QUEUED_INTERRUPTS) != 0)
122 /* Is the iterator pointing to a sigreturn trampoline? */
123 static int is_sigreturn(struct KBacktraceIterator *kbt)
125 return kbt->task->mm &&
126 (kbt->it.pc == ((ulong)kbt->task->mm->context.vdso_base +
127 (ulong)&__vdso_rt_sigreturn));
130 /* Return a pt_regs pointer for a valid signal handler frame */
131 static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt,
132 struct rt_sigframe* kframe)
134 BacktraceIterator *b = &kbt->it;
136 if (is_sigreturn(kbt) && b->sp < PAGE_OFFSET &&
137 b->sp % sizeof(long) == 0) {
140 retval = __copy_from_user_inatomic(
141 kframe, (void __user __force *)b->sp,
145 (unsigned int)(kframe->info.si_signo) >= _NSIG)
148 pr_err(" <received signal %d>\n",
149 kframe->info.si_signo);
151 return (struct pt_regs *)&kframe->uc.uc_mcontext;
156 static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt)
159 struct rt_sigframe kframe;
161 p = valid_fault_handler(kbt);
163 p = valid_sigframe(kbt, &kframe);
166 backtrace_init(&kbt->it, read_memory_func, kbt,
167 p->pc, p->lr, p->sp, p->regs[52]);
168 kbt->new_context = 1;
172 /* Find a frame that isn't a sigreturn, if there is one. */
173 static int KBacktraceIterator_next_item_inclusive(
174 struct KBacktraceIterator *kbt)
178 if (!is_sigreturn(kbt))
180 } while (backtrace_next(&kbt->it));
182 if (!KBacktraceIterator_restart(kbt))
188 * If the current sp is on a page different than what we recorded
189 * as the top-of-kernel-stack last time we context switched, we have
190 * probably blown the stack, and nothing is going to work out well.
191 * If we can at least get out a warning, that may help the debug,
192 * though we probably won't be able to backtrace into the code that
193 * actually did the recursive damage.
195 static void validate_stack(struct pt_regs *regs)
197 int cpu = raw_smp_processor_id();
198 unsigned long ksp0 = get_current_ksp0();
199 unsigned long ksp0_base = ksp0 & -THREAD_SIZE;
200 unsigned long sp = stack_pointer;
202 if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) {
203 pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx underrun!\n"
204 " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
205 cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
208 else if (sp < ksp0_base + sizeof(struct thread_info)) {
209 pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx overrun!\n"
210 " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
211 cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
215 void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
216 struct task_struct *t, struct pt_regs *regs)
218 unsigned long pc, lr, sp, r52;
222 * Set up callback information. We grab the kernel stack base
223 * so we will allow reads of that address range.
225 is_current = (t == NULL || t == current);
226 kbt->is_current = is_current;
228 t = validate_current();
230 kbt->verbose = 0; /* override in caller if desired */
231 kbt->profile = 0; /* override in caller if desired */
232 kbt->end = KBT_ONGOING;
233 kbt->new_context = 1;
235 validate_stack(regs);
238 if (is_current || t->state == TASK_RUNNING) {
239 /* Can't do this; we need registers */
240 kbt->end = KBT_RUNNING;
243 pc = get_switch_to_pc();
251 r52 = regs->regs[52];
254 backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52);
255 kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
257 EXPORT_SYMBOL(KBacktraceIterator_init);
259 int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
261 return kbt->end != KBT_ONGOING;
263 EXPORT_SYMBOL(KBacktraceIterator_end);
265 void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
267 unsigned long old_pc = kbt->it.pc, old_sp = kbt->it.sp;
268 kbt->new_context = 0;
269 if (!backtrace_next(&kbt->it) && !KBacktraceIterator_restart(kbt)) {
273 kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
274 if (old_pc == kbt->it.pc && old_sp == kbt->it.sp) {
275 /* Trapped in a loop; give up. */
279 EXPORT_SYMBOL(KBacktraceIterator_next);
281 static void describe_addr(struct KBacktraceIterator *kbt,
282 unsigned long address,
283 int have_mmap_sem, char *buf, size_t bufsize)
285 struct vm_area_struct *vma;
286 size_t namelen, remaining;
287 unsigned long size, offset, adjust;
293 * Look one byte back for every caller frame (i.e. those that
294 * aren't a new context) so we look up symbol data for the
295 * call itself, not the following instruction, which may be on
296 * a different line (or in a different function).
298 adjust = !kbt->new_context;
301 if (address >= PAGE_OFFSET) {
302 /* Handle kernel symbols. */
303 BUG_ON(bufsize < KSYM_NAME_LEN);
304 name = kallsyms_lookup(address, &size, &offset,
310 namelen = strlen(buf);
311 remaining = (bufsize - 1) - namelen;
313 rc = snprintf(p, remaining, "+%#lx/%#lx ",
314 offset + adjust, size);
315 if (modname && rc < remaining)
316 snprintf(p + rc, remaining - rc, "[%s] ", modname);
317 buf[bufsize-1] = '\0';
321 /* If we don't have the mmap_sem, we can't show any more info. */
327 vma = find_vma(kbt->task->mm, address);
328 if (vma == NULL || address < vma->vm_start) {
329 snprintf(buf, bufsize, "[unmapped address] ");
334 p = file_path(vma->vm_file, buf, bufsize);
342 /* Generate a string description of the vma info. */
343 namelen = strlen(name);
344 remaining = (bufsize - 1) - namelen;
345 memmove(buf, name, namelen);
346 snprintf(buf + namelen, remaining, "[%lx+%lx] ",
347 vma->vm_start, vma->vm_end - vma->vm_start);
351 * Avoid possible crash recursion during backtrace. If it happens, it
352 * makes it easy to lose the actual root cause of the failure, so we
353 * put a simple guard on all the backtrace loops.
355 static bool start_backtrace(void)
357 if (current_thread_info()->in_backtrace) {
358 pr_err("Backtrace requested while in backtrace!\n");
361 current_thread_info()->in_backtrace = true;
365 static void end_backtrace(void)
367 current_thread_info()->in_backtrace = false;
371 * This method wraps the backtracer's more generic support.
372 * It is only invoked from the architecture-specific code; show_stack()
373 * and dump_stack() are architecture-independent entry points.
375 void tile_show_stack(struct KBacktraceIterator *kbt)
378 int have_mmap_sem = 0;
380 if (!start_backtrace())
384 for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) {
385 char namebuf[KSYM_NAME_LEN+100];
386 unsigned long address = kbt->it.pc;
389 * Try to acquire the mmap_sem as we pass into userspace.
390 * If we're in an interrupt context, don't even try, since
391 * it's not safe to call e.g. d_path() from an interrupt,
392 * since it uses spin locks without disabling interrupts.
393 * Note we test "kbt->task == current", not "kbt->is_current",
394 * since we're checking that "current" will work in d_path().
396 if (kbt->task == current && address < PAGE_OFFSET &&
397 !have_mmap_sem && kbt->task->mm && !in_interrupt()) {
399 down_read_trylock(&kbt->task->mm->mmap_sem);
402 describe_addr(kbt, address, have_mmap_sem,
403 namebuf, sizeof(namebuf));
405 pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n",
406 i++, address, namebuf, (unsigned long)(kbt->it.sp));
409 pr_err("Stack dump truncated (%d frames)\n", i);
413 if (kbt->end == KBT_LOOP)
414 pr_err("Stack dump stopped; next frame identical to this one\n");
416 up_read(&kbt->task->mm->mmap_sem);
419 EXPORT_SYMBOL(tile_show_stack);
421 static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs,
422 ulong pc, ulong lr, ulong sp, ulong r52)
424 memset(regs, 0, sizeof(struct pt_regs));
428 regs->regs[52] = r52;
432 /* Deprecated function currently only used by kernel_double_fault(). */
433 void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
435 struct KBacktraceIterator kbt;
438 regs_to_pt_regs(®s, pc, lr, sp, r52);
439 KBacktraceIterator_init(&kbt, NULL, ®s);
440 tile_show_stack(&kbt);
443 /* This is called from KBacktraceIterator_init_current() */
444 void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc,
445 ulong lr, ulong sp, ulong r52)
448 KBacktraceIterator_init(kbt, NULL,
449 regs_to_pt_regs(®s, pc, lr, sp, r52));
453 * Called from sched_show_task() with task != NULL, or dump_stack()
454 * with task == NULL. The esp argument is always NULL.
456 void show_stack(struct task_struct *task, unsigned long *esp)
458 struct KBacktraceIterator kbt;
459 if (task == NULL || task == current) {
460 KBacktraceIterator_init_current(&kbt);
461 KBacktraceIterator_next(&kbt); /* don't show first frame */
463 KBacktraceIterator_init(&kbt, task, NULL);
465 tile_show_stack(&kbt);
468 #ifdef CONFIG_STACKTRACE
470 /* Support generic Linux stack API too */
472 static void save_stack_trace_common(struct task_struct *task,
473 struct pt_regs *regs,
475 struct stack_trace *trace)
477 struct KBacktraceIterator kbt;
478 int skip = trace->skip;
481 if (!start_backtrace())
484 KBacktraceIterator_init(&kbt, NULL, regs);
485 } else if (task == NULL || task == current) {
486 KBacktraceIterator_init_current(&kbt);
487 skip++; /* don't show KBacktraceIterator_init_current */
489 KBacktraceIterator_init(&kbt, task, NULL);
491 for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) {
496 if (i >= trace->max_entries ||
497 (!user && kbt.it.pc < PAGE_OFFSET))
499 trace->entries[i++] = kbt.it.pc;
503 if (i < trace->max_entries)
504 trace->entries[i++] = ULONG_MAX;
505 trace->nr_entries = i;
508 void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
510 save_stack_trace_common(task, NULL, false, trace);
512 EXPORT_SYMBOL(save_stack_trace_tsk);
514 void save_stack_trace(struct stack_trace *trace)
516 save_stack_trace_common(NULL, NULL, false, trace);
518 EXPORT_SYMBOL_GPL(save_stack_trace);
520 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
522 save_stack_trace_common(NULL, regs, false, trace);
525 void save_stack_trace_user(struct stack_trace *trace)
527 /* Trace user stack if we are not a kernel thread. */
529 save_stack_trace_common(NULL, task_pt_regs(current),
531 else if (trace->nr_entries < trace->max_entries)
532 trace->entries[trace->nr_entries++] = ULONG_MAX;
537 EXPORT_SYMBOL(KBacktraceIterator_init_current);