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);
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 pc pointing to a sigreturn trampoline? */
123 static int is_sigreturn(unsigned long pc)
125 return current->mm && (pc == VDSO_SYM(&__vdso_rt_sigreturn));
128 /* Return a pt_regs pointer for a valid signal handler frame */
129 static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt,
130 struct rt_sigframe* kframe)
132 BacktraceIterator *b = &kbt->it;
134 if (is_sigreturn(b->pc) && b->sp < PAGE_OFFSET &&
135 b->sp % sizeof(long) == 0) {
138 retval = __copy_from_user_inatomic(
139 kframe, (void __user __force *)b->sp,
143 (unsigned int)(kframe->info.si_signo) >= _NSIG)
146 pr_err(" <received signal %d>\n",
147 kframe->info.si_signo);
149 return (struct pt_regs *)&kframe->uc.uc_mcontext;
154 static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
156 return is_sigreturn(kbt->it.pc);
159 static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt)
162 struct rt_sigframe kframe;
164 p = valid_fault_handler(kbt);
166 p = valid_sigframe(kbt, &kframe);
169 backtrace_init(&kbt->it, read_memory_func, kbt,
170 p->pc, p->lr, p->sp, p->regs[52]);
171 kbt->new_context = 1;
175 /* Find a frame that isn't a sigreturn, if there is one. */
176 static int KBacktraceIterator_next_item_inclusive(
177 struct KBacktraceIterator *kbt)
181 if (!KBacktraceIterator_is_sigreturn(kbt))
183 } while (backtrace_next(&kbt->it));
185 if (!KBacktraceIterator_restart(kbt))
191 * If the current sp is on a page different than what we recorded
192 * as the top-of-kernel-stack last time we context switched, we have
193 * probably blown the stack, and nothing is going to work out well.
194 * If we can at least get out a warning, that may help the debug,
195 * though we probably won't be able to backtrace into the code that
196 * actually did the recursive damage.
198 static void validate_stack(struct pt_regs *regs)
200 int cpu = raw_smp_processor_id();
201 unsigned long ksp0 = get_current_ksp0();
202 unsigned long ksp0_base = ksp0 & -THREAD_SIZE;
203 unsigned long sp = stack_pointer;
205 if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) {
206 pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx underrun!\n"
207 " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
208 cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
211 else if (sp < ksp0_base + sizeof(struct thread_info)) {
212 pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx overrun!\n"
213 " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
214 cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
218 void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
219 struct task_struct *t, struct pt_regs *regs)
221 unsigned long pc, lr, sp, r52;
225 * Set up callback information. We grab the kernel stack base
226 * so we will allow reads of that address range.
228 is_current = (t == NULL || t == current);
229 kbt->is_current = is_current;
231 t = validate_current();
233 kbt->verbose = 0; /* override in caller if desired */
234 kbt->profile = 0; /* override in caller if desired */
235 kbt->end = KBT_ONGOING;
236 kbt->new_context = 1;
238 validate_stack(regs);
241 if (is_current || t->state == TASK_RUNNING) {
242 /* Can't do this; we need registers */
243 kbt->end = KBT_RUNNING;
246 pc = get_switch_to_pc();
254 r52 = regs->regs[52];
257 backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52);
258 kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
260 EXPORT_SYMBOL(KBacktraceIterator_init);
262 int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
264 return kbt->end != KBT_ONGOING;
266 EXPORT_SYMBOL(KBacktraceIterator_end);
268 void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
270 unsigned long old_pc = kbt->it.pc, old_sp = kbt->it.sp;
271 kbt->new_context = 0;
272 if (!backtrace_next(&kbt->it) && !KBacktraceIterator_restart(kbt)) {
276 kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
277 if (old_pc == kbt->it.pc && old_sp == kbt->it.sp) {
278 /* Trapped in a loop; give up. */
282 EXPORT_SYMBOL(KBacktraceIterator_next);
284 static void describe_addr(struct KBacktraceIterator *kbt,
285 unsigned long address,
286 int have_mmap_sem, char *buf, size_t bufsize)
288 struct vm_area_struct *vma;
289 size_t namelen, remaining;
290 unsigned long size, offset, adjust;
296 * Look one byte back for every caller frame (i.e. those that
297 * aren't a new context) so we look up symbol data for the
298 * call itself, not the following instruction, which may be on
299 * a different line (or in a different function).
301 adjust = !kbt->new_context;
304 if (address >= PAGE_OFFSET) {
305 /* Handle kernel symbols. */
306 BUG_ON(bufsize < KSYM_NAME_LEN);
307 name = kallsyms_lookup(address, &size, &offset,
313 namelen = strlen(buf);
314 remaining = (bufsize - 1) - namelen;
316 rc = snprintf(p, remaining, "+%#lx/%#lx ",
317 offset + adjust, size);
318 if (modname && rc < remaining)
319 snprintf(p + rc, remaining - rc, "[%s] ", modname);
320 buf[bufsize-1] = '\0';
324 /* If we don't have the mmap_sem, we can't show any more info. */
330 vma = find_vma(kbt->task->mm, address);
331 if (vma == NULL || address < vma->vm_start) {
332 snprintf(buf, bufsize, "[unmapped address] ");
337 p = d_path(&vma->vm_file->f_path, buf, bufsize);
345 /* Generate a string description of the vma info. */
346 namelen = strlen(name);
347 remaining = (bufsize - 1) - namelen;
348 memmove(buf, name, namelen);
349 snprintf(buf + namelen, remaining, "[%lx+%lx] ",
350 vma->vm_start, vma->vm_end - vma->vm_start);
354 * Avoid possible crash recursion during backtrace. If it happens, it
355 * makes it easy to lose the actual root cause of the failure, so we
356 * put a simple guard on all the backtrace loops.
358 static bool start_backtrace(void)
360 if (current->thread.in_backtrace) {
361 pr_err("Backtrace requested while in backtrace!\n");
364 current->thread.in_backtrace = true;
368 static void end_backtrace(void)
370 current->thread.in_backtrace = false;
374 * This method wraps the backtracer's more generic support.
375 * It is only invoked from the architecture-specific code; show_stack()
376 * and dump_stack() (in entry.S) are architecture-independent entry points.
378 void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
381 int have_mmap_sem = 0;
383 if (!start_backtrace())
387 * Add a blank line since if we are called from panic(),
388 * then bust_spinlocks() spit out a space in front of us
389 * and it will mess up our KERN_ERR.
391 pr_err("Starting stack dump of tid %d, pid %d (%s) on cpu %d at cycle %lld\n",
392 kbt->task->pid, kbt->task->tgid, kbt->task->comm,
393 raw_smp_processor_id(), get_cycles());
397 for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) {
398 char namebuf[KSYM_NAME_LEN+100];
399 unsigned long address = kbt->it.pc;
401 /* Try to acquire the mmap_sem as we pass into userspace. */
402 if (address < PAGE_OFFSET && !have_mmap_sem && kbt->task->mm)
404 down_read_trylock(&kbt->task->mm->mmap_sem);
406 describe_addr(kbt, address, have_mmap_sem,
407 namebuf, sizeof(namebuf));
409 pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n",
410 i++, address, namebuf, (unsigned long)(kbt->it.sp));
413 pr_err("Stack dump truncated (%d frames)\n", i);
417 if (kbt->end == KBT_LOOP)
418 pr_err("Stack dump stopped; next frame identical to this one\n");
420 pr_err("Stack dump complete\n");
422 up_read(&kbt->task->mm->mmap_sem);
425 EXPORT_SYMBOL(tile_show_stack);
428 /* This is called from show_regs() and _dump_stack() */
429 void dump_stack_regs(struct pt_regs *regs)
431 struct KBacktraceIterator kbt;
432 KBacktraceIterator_init(&kbt, NULL, regs);
433 tile_show_stack(&kbt, 1);
435 EXPORT_SYMBOL(dump_stack_regs);
437 static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs,
438 ulong pc, ulong lr, ulong sp, ulong r52)
440 memset(regs, 0, sizeof(struct pt_regs));
444 regs->regs[52] = r52;
448 /* This is called from dump_stack() and just converts to pt_regs */
449 void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
452 dump_stack_regs(regs_to_pt_regs(®s, pc, lr, sp, r52));
455 /* This is called from KBacktraceIterator_init_current() */
456 void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc,
457 ulong lr, ulong sp, ulong r52)
460 KBacktraceIterator_init(kbt, NULL,
461 regs_to_pt_regs(®s, pc, lr, sp, r52));
464 /* This is called only from kernel/sched/core.c, with esp == NULL */
465 void show_stack(struct task_struct *task, unsigned long *esp)
467 struct KBacktraceIterator kbt;
468 if (task == NULL || task == current)
469 KBacktraceIterator_init_current(&kbt);
471 KBacktraceIterator_init(&kbt, task, NULL);
472 tile_show_stack(&kbt, 0);
475 #ifdef CONFIG_STACKTRACE
477 /* Support generic Linux stack API too */
479 void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
481 struct KBacktraceIterator kbt;
482 int skip = trace->skip;
485 if (!start_backtrace())
487 if (task == NULL || task == current)
488 KBacktraceIterator_init_current(&kbt);
490 KBacktraceIterator_init(&kbt, task, NULL);
491 for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) {
496 if (i >= trace->max_entries || kbt.it.pc < PAGE_OFFSET)
498 trace->entries[i++] = kbt.it.pc;
502 trace->nr_entries = i;
504 EXPORT_SYMBOL(save_stack_trace_tsk);
506 void save_stack_trace(struct stack_trace *trace)
508 save_stack_trace_tsk(NULL, trace);
510 EXPORT_SYMBOL_GPL(save_stack_trace);
515 EXPORT_SYMBOL(KBacktraceIterator_init_current);