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/string.h>
27 #include <asm/backtrace.h>
29 #include <asm/ucontext.h>
30 #include <asm/switch_to.h>
31 #include <asm/sigframe.h>
32 #include <asm/stack.h>
35 #include <arch/interrupts.h>
37 #define KBT_ONGOING 0 /* Backtrace still ongoing */
38 #define KBT_DONE 1 /* Backtrace cleanly completed */
39 #define KBT_RUNNING 2 /* Can't run backtrace on a running task */
40 #define KBT_LOOP 3 /* Backtrace entered a loop */
42 /* Is address on the specified kernel stack? */
43 static int in_kernel_stack(struct KBacktraceIterator *kbt, unsigned long sp)
45 ulong kstack_base = (ulong) kbt->task->stack;
46 if (kstack_base == 0) /* corrupt task pointer; just follow stack... */
47 return sp >= PAGE_OFFSET && sp < (unsigned long)high_memory;
48 return sp >= kstack_base && sp < kstack_base + THREAD_SIZE;
51 /* Callback for backtracer; basically a glorified memcpy */
52 static bool read_memory_func(void *result, unsigned long address,
53 unsigned int size, void *vkbt)
56 struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;
60 if (__kernel_text_address(address)) {
61 /* OK to read kernel code. */
62 } else if (address >= PAGE_OFFSET) {
63 /* We only tolerate kernel-space reads of this task's stack */
64 if (!in_kernel_stack(kbt, address))
66 } else if (!kbt->is_current) {
67 return 0; /* can't read from other user address spaces */
70 retval = __copy_from_user_inatomic(result,
71 (void __user __force *)address,
77 /* Return a pt_regs pointer for a valid fault handler frame */
78 static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
80 const char *fault = NULL; /* happy compiler */
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 (p->faultnum == INT_SWINT_1 || p->faultnum == INT_SWINT_1_SIGRETURN)
95 if (kbt->verbose) { /* else we aren't going to use it */
96 snprintf(fault_buf, sizeof(fault_buf),
97 "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);
111 } else if (kbt->verbose) {
112 pr_err(" (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n",
113 p->pc, p->sp, p->ex1);
116 if (!kbt->profile || ((1ULL << p->faultnum) & QUEUED_INTERRUPTS) == 0)
121 /* Is the pc pointing to a sigreturn trampoline? */
122 static int is_sigreturn(unsigned long pc)
124 return current->mm && (pc == VDSO_SYM(&__vdso_rt_sigreturn));
127 /* Return a pt_regs pointer for a valid signal handler frame */
128 static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt,
129 struct rt_sigframe* kframe)
131 BacktraceIterator *b = &kbt->it;
133 if (is_sigreturn(b->pc) && b->sp < PAGE_OFFSET &&
134 b->sp % sizeof(long) == 0) {
137 retval = __copy_from_user_inatomic(
138 kframe, (void __user __force *)b->sp,
142 (unsigned int)(kframe->info.si_signo) >= _NSIG)
145 pr_err(" <received signal %d>\n",
146 kframe->info.si_signo);
148 return (struct pt_regs *)&kframe->uc.uc_mcontext;
153 static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
155 return is_sigreturn(kbt->it.pc);
158 static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt)
161 struct rt_sigframe kframe;
163 p = valid_fault_handler(kbt);
165 p = valid_sigframe(kbt, &kframe);
168 backtrace_init(&kbt->it, read_memory_func, kbt,
169 p->pc, p->lr, p->sp, p->regs[52]);
170 kbt->new_context = 1;
174 /* Find a frame that isn't a sigreturn, if there is one. */
175 static int KBacktraceIterator_next_item_inclusive(
176 struct KBacktraceIterator *kbt)
180 if (!KBacktraceIterator_is_sigreturn(kbt))
182 } while (backtrace_next(&kbt->it));
184 if (!KBacktraceIterator_restart(kbt))
190 * If the current sp is on a page different than what we recorded
191 * as the top-of-kernel-stack last time we context switched, we have
192 * probably blown the stack, and nothing is going to work out well.
193 * If we can at least get out a warning, that may help the debug,
194 * though we probably won't be able to backtrace into the code that
195 * actually did the recursive damage.
197 static void validate_stack(struct pt_regs *regs)
199 int cpu = raw_smp_processor_id();
200 unsigned long ksp0 = get_current_ksp0();
201 unsigned long ksp0_base = ksp0 & -THREAD_SIZE;
202 unsigned long sp = stack_pointer;
204 if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) {
205 pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx underrun!\n"
206 " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
207 cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
210 else if (sp < ksp0_base + sizeof(struct thread_info)) {
211 pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx overrun!\n"
212 " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
213 cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
217 void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
218 struct task_struct *t, struct pt_regs *regs)
220 unsigned long pc, lr, sp, r52;
224 * Set up callback information. We grab the kernel stack base
225 * so we will allow reads of that address range.
227 is_current = (t == NULL || t == current);
228 kbt->is_current = is_current;
230 t = validate_current();
232 kbt->verbose = 0; /* override in caller if desired */
233 kbt->profile = 0; /* override in caller if desired */
234 kbt->end = KBT_ONGOING;
235 kbt->new_context = 1;
237 validate_stack(regs);
240 if (is_current || t->state == TASK_RUNNING) {
241 /* Can't do this; we need registers */
242 kbt->end = KBT_RUNNING;
245 pc = get_switch_to_pc();
253 r52 = regs->regs[52];
256 backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52);
257 kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
259 EXPORT_SYMBOL(KBacktraceIterator_init);
261 int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
263 return kbt->end != KBT_ONGOING;
265 EXPORT_SYMBOL(KBacktraceIterator_end);
267 void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
269 unsigned long old_pc = kbt->it.pc, old_sp = kbt->it.sp;
270 kbt->new_context = 0;
271 if (!backtrace_next(&kbt->it) && !KBacktraceIterator_restart(kbt)) {
275 kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
276 if (old_pc == kbt->it.pc && old_sp == kbt->it.sp) {
277 /* Trapped in a loop; give up. */
281 EXPORT_SYMBOL(KBacktraceIterator_next);
283 static void describe_addr(struct KBacktraceIterator *kbt,
284 unsigned long address,
285 int have_mmap_sem, char *buf, size_t bufsize)
287 struct vm_area_struct *vma;
288 size_t namelen, remaining;
289 unsigned long size, offset, adjust;
295 * Look one byte back for every caller frame (i.e. those that
296 * aren't a new context) so we look up symbol data for the
297 * call itself, not the following instruction, which may be on
298 * a different line (or in a different function).
300 adjust = !kbt->new_context;
303 if (address >= PAGE_OFFSET) {
304 /* Handle kernel symbols. */
305 BUG_ON(bufsize < KSYM_NAME_LEN);
306 name = kallsyms_lookup(address, &size, &offset,
312 namelen = strlen(buf);
313 remaining = (bufsize - 1) - namelen;
315 rc = snprintf(p, remaining, "+%#lx/%#lx ",
316 offset + adjust, size);
317 if (modname && rc < remaining)
318 snprintf(p + rc, remaining - rc, "[%s] ", modname);
319 buf[bufsize-1] = '\0';
323 /* If we don't have the mmap_sem, we can't show any more info. */
329 vma = find_vma(kbt->task->mm, address);
330 if (vma == NULL || address < vma->vm_start) {
331 snprintf(buf, bufsize, "[unmapped address] ");
336 p = d_path(&vma->vm_file->f_path, buf, bufsize);
344 /* Generate a string description of the vma info. */
345 namelen = strlen(name);
346 remaining = (bufsize - 1) - namelen;
347 memmove(buf, name, namelen);
348 snprintf(buf + namelen, remaining, "[%lx+%lx] ",
349 vma->vm_start, vma->vm_end - vma->vm_start);
353 * Avoid possible crash recursion during backtrace. If it happens, it
354 * makes it easy to lose the actual root cause of the failure, so we
355 * put a simple guard on all the backtrace loops.
357 static bool start_backtrace(void)
359 if (current->thread.in_backtrace) {
360 pr_err("Backtrace requested while in backtrace!\n");
363 current->thread.in_backtrace = true;
367 static void end_backtrace(void)
369 current->thread.in_backtrace = false;
373 * This method wraps the backtracer's more generic support.
374 * It is only invoked from the architecture-specific code; show_stack()
375 * and dump_stack() (in entry.S) are architecture-independent entry points.
377 void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
380 int have_mmap_sem = 0;
382 if (!start_backtrace())
386 * Add a blank line since if we are called from panic(),
387 * then bust_spinlocks() spit out a space in front of us
388 * and it will mess up our KERN_ERR.
391 pr_err("Starting stack dump of tid %d, pid %d (%s)"
392 " on cpu %d at cycle %lld\n",
393 kbt->task->pid, kbt->task->tgid, kbt->task->comm,
394 raw_smp_processor_id(), get_cycles());
398 for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) {
399 char namebuf[KSYM_NAME_LEN+100];
400 unsigned long address = kbt->it.pc;
402 /* Try to acquire the mmap_sem as we pass into userspace. */
403 if (address < PAGE_OFFSET && !have_mmap_sem && kbt->task->mm)
405 down_read_trylock(&kbt->task->mm->mmap_sem);
407 describe_addr(kbt, address, have_mmap_sem,
408 namebuf, sizeof(namebuf));
410 pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n",
411 i++, address, namebuf, (unsigned long)(kbt->it.sp));
414 pr_err("Stack dump truncated"
415 " (%d frames)\n", i);
419 if (kbt->end == KBT_LOOP)
420 pr_err("Stack dump stopped; next frame identical to this one\n");
422 pr_err("Stack dump complete\n");
424 up_read(&kbt->task->mm->mmap_sem);
427 EXPORT_SYMBOL(tile_show_stack);
430 /* This is called from show_regs() and _dump_stack() */
431 void dump_stack_regs(struct pt_regs *regs)
433 struct KBacktraceIterator kbt;
434 KBacktraceIterator_init(&kbt, NULL, regs);
435 tile_show_stack(&kbt, 1);
437 EXPORT_SYMBOL(dump_stack_regs);
439 static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs,
440 ulong pc, ulong lr, ulong sp, ulong r52)
442 memset(regs, 0, sizeof(struct pt_regs));
446 regs->regs[52] = r52;
450 /* This is called from dump_stack() and just converts to pt_regs */
451 void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
454 dump_stack_regs(regs_to_pt_regs(®s, pc, lr, sp, r52));
457 /* This is called from KBacktraceIterator_init_current() */
458 void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc,
459 ulong lr, ulong sp, ulong r52)
462 KBacktraceIterator_init(kbt, NULL,
463 regs_to_pt_regs(®s, pc, lr, sp, r52));
466 /* This is called only from kernel/sched/core.c, with esp == NULL */
467 void show_stack(struct task_struct *task, unsigned long *esp)
469 struct KBacktraceIterator kbt;
470 if (task == NULL || task == current)
471 KBacktraceIterator_init_current(&kbt);
473 KBacktraceIterator_init(&kbt, task, NULL);
474 tile_show_stack(&kbt, 0);
477 #ifdef CONFIG_STACKTRACE
479 /* Support generic Linux stack API too */
481 void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
483 struct KBacktraceIterator kbt;
484 int skip = trace->skip;
487 if (!start_backtrace())
489 if (task == NULL || task == current)
490 KBacktraceIterator_init_current(&kbt);
492 KBacktraceIterator_init(&kbt, task, NULL);
493 for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) {
498 if (i >= trace->max_entries || kbt.it.pc < PAGE_OFFSET)
500 trace->entries[i++] = kbt.it.pc;
504 trace->nr_entries = i;
506 EXPORT_SYMBOL(save_stack_trace_tsk);
508 void save_stack_trace(struct stack_trace *trace)
510 save_stack_trace_tsk(NULL, trace);
512 EXPORT_SYMBOL_GPL(save_stack_trace);
517 EXPORT_SYMBOL(KBacktraceIterator_init_current);