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867e359b CM |
1 | /* |
2 | * Copyright 2010 Tilera Corporation. All Rights Reserved. | |
3 | * | |
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. | |
7 | * | |
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 | |
12 | * more details. | |
13 | */ | |
14 | ||
15 | #include <linux/sched.h> | |
b17b0153 | 16 | #include <linux/sched/debug.h> |
68db0cf1 | 17 | #include <linux/sched/task_stack.h> |
867e359b CM |
18 | #include <linux/kernel.h> |
19 | #include <linux/kprobes.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/pfn.h> | |
22 | #include <linux/kallsyms.h> | |
23 | #include <linux/stacktrace.h> | |
24 | #include <linux/uaccess.h> | |
25 | #include <linux/mmzone.h> | |
5f639fdc CM |
26 | #include <linux/dcache.h> |
27 | #include <linux/fs.h> | |
47ad7b9b | 28 | #include <linux/hardirq.h> |
0cc96a74 | 29 | #include <linux/string.h> |
867e359b CM |
30 | #include <asm/backtrace.h> |
31 | #include <asm/page.h> | |
867e359b | 32 | #include <asm/ucontext.h> |
34f2c0ac | 33 | #include <asm/switch_to.h> |
867e359b CM |
34 | #include <asm/sigframe.h> |
35 | #include <asm/stack.h> | |
4a556f4f | 36 | #include <asm/vdso.h> |
867e359b CM |
37 | #include <arch/abi.h> |
38 | #include <arch/interrupts.h> | |
39 | ||
dabe98c9 CM |
40 | #define KBT_ONGOING 0 /* Backtrace still ongoing */ |
41 | #define KBT_DONE 1 /* Backtrace cleanly completed */ | |
42 | #define KBT_RUNNING 2 /* Can't run backtrace on a running task */ | |
43 | #define KBT_LOOP 3 /* Backtrace entered a loop */ | |
867e359b CM |
44 | |
45 | /* Is address on the specified kernel stack? */ | |
93013a0f | 46 | static int in_kernel_stack(struct KBacktraceIterator *kbt, unsigned long sp) |
867e359b CM |
47 | { |
48 | ulong kstack_base = (ulong) kbt->task->stack; | |
49 | if (kstack_base == 0) /* corrupt task pointer; just follow stack... */ | |
50 | return sp >= PAGE_OFFSET && sp < (unsigned long)high_memory; | |
51 | return sp >= kstack_base && sp < kstack_base + THREAD_SIZE; | |
52 | } | |
53 | ||
867e359b | 54 | /* Callback for backtracer; basically a glorified memcpy */ |
93013a0f | 55 | static bool read_memory_func(void *result, unsigned long address, |
867e359b CM |
56 | unsigned int size, void *vkbt) |
57 | { | |
58 | int retval; | |
59 | struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt; | |
5f639fdc CM |
60 | |
61 | if (address == 0) | |
62 | return 0; | |
3cebbafd | 63 | if (__kernel_text_address(address)) { |
867e359b CM |
64 | /* OK to read kernel code. */ |
65 | } else if (address >= PAGE_OFFSET) { | |
66 | /* We only tolerate kernel-space reads of this task's stack */ | |
67 | if (!in_kernel_stack(kbt, address)) | |
68 | return 0; | |
5f639fdc CM |
69 | } else if (!kbt->is_current) { |
70 | return 0; /* can't read from other user address spaces */ | |
867e359b CM |
71 | } |
72 | pagefault_disable(); | |
0707ad30 CM |
73 | retval = __copy_from_user_inatomic(result, |
74 | (void __user __force *)address, | |
867e359b CM |
75 | size); |
76 | pagefault_enable(); | |
77 | return (retval == 0); | |
78 | } | |
79 | ||
80 | /* Return a pt_regs pointer for a valid fault handler frame */ | |
81 | static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt) | |
82 | { | |
5ac65abd | 83 | char fault[64]; |
93013a0f | 84 | unsigned long sp = kbt->it.sp; |
867e359b CM |
85 | struct pt_regs *p; |
86 | ||
5f639fdc CM |
87 | if (sp % sizeof(long) != 0) |
88 | return NULL; | |
867e359b CM |
89 | if (!in_kernel_stack(kbt, sp)) |
90 | return NULL; | |
91 | if (!in_kernel_stack(kbt, sp + C_ABI_SAVE_AREA_SIZE + PTREGS_SIZE-1)) | |
92 | return NULL; | |
93 | p = (struct pt_regs *)(sp + C_ABI_SAVE_AREA_SIZE); | |
5ac65abd CM |
94 | if (kbt->verbose) { /* else we aren't going to use it */ |
95 | if (p->faultnum == INT_SWINT_1 || | |
96 | p->faultnum == INT_SWINT_1_SIGRETURN) | |
97 | snprintf(fault, sizeof(fault), | |
98 | "syscall %ld", p->regs[TREG_SYSCALL_NR]); | |
99 | else | |
100 | snprintf(fault, sizeof(fault), | |
867e359b | 101 | "interrupt %ld", p->faultnum); |
867e359b CM |
102 | } |
103 | if (EX1_PL(p->ex1) == KERNEL_PL && | |
3cebbafd | 104 | __kernel_text_address(p->pc) && |
867e359b CM |
105 | in_kernel_stack(kbt, p->sp) && |
106 | p->sp >= sp) { | |
107 | if (kbt->verbose) | |
0707ad30 | 108 | pr_err(" <%s while in kernel mode>\n", fault); |
051168df | 109 | } else if (user_mode(p) && |
3ef23111 | 110 | p->sp < PAGE_OFFSET && p->sp != 0) { |
867e359b | 111 | if (kbt->verbose) |
0707ad30 | 112 | pr_err(" <%s while in user mode>\n", fault); |
9088616f | 113 | } else { |
47ad7b9b | 114 | if (kbt->verbose && (p->pc != 0 || p->sp != 0 || p->ex1 != 0)) |
9088616f CIK |
115 | pr_err(" (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n", |
116 | p->pc, p->sp, p->ex1); | |
117 | return NULL; | |
867e359b | 118 | } |
9088616f CIK |
119 | if (kbt->profile && ((1ULL << p->faultnum) & QUEUED_INTERRUPTS) != 0) |
120 | return NULL; | |
121 | return p; | |
867e359b CM |
122 | } |
123 | ||
47ad7b9b CM |
124 | /* Is the iterator pointing to a sigreturn trampoline? */ |
125 | static int is_sigreturn(struct KBacktraceIterator *kbt) | |
867e359b | 126 | { |
47ad7b9b CM |
127 | return kbt->task->mm && |
128 | (kbt->it.pc == ((ulong)kbt->task->mm->context.vdso_base + | |
129 | (ulong)&__vdso_rt_sigreturn)); | |
867e359b CM |
130 | } |
131 | ||
132 | /* Return a pt_regs pointer for a valid signal handler frame */ | |
5f639fdc CM |
133 | static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt, |
134 | struct rt_sigframe* kframe) | |
867e359b CM |
135 | { |
136 | BacktraceIterator *b = &kbt->it; | |
137 | ||
47ad7b9b | 138 | if (is_sigreturn(kbt) && b->sp < PAGE_OFFSET && |
5f639fdc CM |
139 | b->sp % sizeof(long) == 0) { |
140 | int retval; | |
141 | pagefault_disable(); | |
142 | retval = __copy_from_user_inatomic( | |
143 | kframe, (void __user __force *)b->sp, | |
144 | sizeof(*kframe)); | |
145 | pagefault_enable(); | |
146 | if (retval != 0 || | |
147 | (unsigned int)(kframe->info.si_signo) >= _NSIG) | |
867e359b | 148 | return NULL; |
867e359b | 149 | if (kbt->verbose) { |
0707ad30 | 150 | pr_err(" <received signal %d>\n", |
5f639fdc | 151 | kframe->info.si_signo); |
867e359b | 152 | } |
5f639fdc | 153 | return (struct pt_regs *)&kframe->uc.uc_mcontext; |
867e359b CM |
154 | } |
155 | return NULL; | |
156 | } | |
157 | ||
867e359b CM |
158 | static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt) |
159 | { | |
160 | struct pt_regs *p; | |
5f639fdc | 161 | struct rt_sigframe kframe; |
867e359b CM |
162 | |
163 | p = valid_fault_handler(kbt); | |
164 | if (p == NULL) | |
5f639fdc | 165 | p = valid_sigframe(kbt, &kframe); |
867e359b CM |
166 | if (p == NULL) |
167 | return 0; | |
168 | backtrace_init(&kbt->it, read_memory_func, kbt, | |
169 | p->pc, p->lr, p->sp, p->regs[52]); | |
170 | kbt->new_context = 1; | |
171 | return 1; | |
172 | } | |
173 | ||
174 | /* Find a frame that isn't a sigreturn, if there is one. */ | |
175 | static int KBacktraceIterator_next_item_inclusive( | |
176 | struct KBacktraceIterator *kbt) | |
177 | { | |
178 | for (;;) { | |
179 | do { | |
47ad7b9b | 180 | if (!is_sigreturn(kbt)) |
dabe98c9 | 181 | return KBT_ONGOING; |
867e359b CM |
182 | } while (backtrace_next(&kbt->it)); |
183 | ||
184 | if (!KBacktraceIterator_restart(kbt)) | |
dabe98c9 | 185 | return KBT_DONE; |
867e359b CM |
186 | } |
187 | } | |
188 | ||
189 | /* | |
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. | |
196 | */ | |
197 | static void validate_stack(struct pt_regs *regs) | |
198 | { | |
bc1a298f | 199 | int cpu = raw_smp_processor_id(); |
867e359b | 200 | unsigned long ksp0 = get_current_ksp0(); |
35f05976 | 201 | unsigned long ksp0_base = ksp0 & -THREAD_SIZE; |
867e359b CM |
202 | unsigned long sp = stack_pointer; |
203 | ||
204 | if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) { | |
35f05976 | 205 | pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx underrun!\n" |
867e359b | 206 | " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n", |
35f05976 | 207 | cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr); |
867e359b CM |
208 | } |
209 | ||
210 | else if (sp < ksp0_base + sizeof(struct thread_info)) { | |
35f05976 | 211 | pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx overrun!\n" |
867e359b | 212 | " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n", |
35f05976 | 213 | cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr); |
867e359b CM |
214 | } |
215 | } | |
216 | ||
217 | void KBacktraceIterator_init(struct KBacktraceIterator *kbt, | |
218 | struct task_struct *t, struct pt_regs *regs) | |
219 | { | |
93013a0f | 220 | unsigned long pc, lr, sp, r52; |
867e359b CM |
221 | int is_current; |
222 | ||
223 | /* | |
224 | * Set up callback information. We grab the kernel stack base | |
5f639fdc | 225 | * so we will allow reads of that address range. |
867e359b | 226 | */ |
5f639fdc | 227 | is_current = (t == NULL || t == current); |
867e359b CM |
228 | kbt->is_current = is_current; |
229 | if (is_current) | |
230 | t = validate_current(); | |
231 | kbt->task = t; | |
867e359b CM |
232 | kbt->verbose = 0; /* override in caller if desired */ |
233 | kbt->profile = 0; /* override in caller if desired */ | |
dabe98c9 | 234 | kbt->end = KBT_ONGOING; |
5f639fdc CM |
235 | kbt->new_context = 1; |
236 | if (is_current) | |
867e359b | 237 | validate_stack(regs); |
867e359b CM |
238 | |
239 | if (regs == NULL) { | |
867e359b CM |
240 | if (is_current || t->state == TASK_RUNNING) { |
241 | /* Can't do this; we need registers */ | |
dabe98c9 | 242 | kbt->end = KBT_RUNNING; |
867e359b CM |
243 | return; |
244 | } | |
0707ad30 | 245 | pc = get_switch_to_pc(); |
867e359b CM |
246 | lr = t->thread.pc; |
247 | sp = t->thread.ksp; | |
248 | r52 = 0; | |
249 | } else { | |
250 | pc = regs->pc; | |
251 | lr = regs->lr; | |
252 | sp = regs->sp; | |
253 | r52 = regs->regs[52]; | |
254 | } | |
255 | ||
256 | backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52); | |
dabe98c9 | 257 | kbt->end = KBacktraceIterator_next_item_inclusive(kbt); |
867e359b CM |
258 | } |
259 | EXPORT_SYMBOL(KBacktraceIterator_init); | |
260 | ||
261 | int KBacktraceIterator_end(struct KBacktraceIterator *kbt) | |
262 | { | |
dabe98c9 | 263 | return kbt->end != KBT_ONGOING; |
867e359b CM |
264 | } |
265 | EXPORT_SYMBOL(KBacktraceIterator_end); | |
266 | ||
267 | void KBacktraceIterator_next(struct KBacktraceIterator *kbt) | |
268 | { | |
93013a0f | 269 | unsigned long old_pc = kbt->it.pc, old_sp = kbt->it.sp; |
867e359b | 270 | kbt->new_context = 0; |
dabe98c9 CM |
271 | if (!backtrace_next(&kbt->it) && !KBacktraceIterator_restart(kbt)) { |
272 | kbt->end = KBT_DONE; | |
273 | return; | |
274 | } | |
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. */ | |
278 | kbt->end = KBT_LOOP; | |
279 | } | |
867e359b CM |
280 | } |
281 | EXPORT_SYMBOL(KBacktraceIterator_next); | |
282 | ||
5f639fdc CM |
283 | static void describe_addr(struct KBacktraceIterator *kbt, |
284 | unsigned long address, | |
285 | int have_mmap_sem, char *buf, size_t bufsize) | |
286 | { | |
287 | struct vm_area_struct *vma; | |
288 | size_t namelen, remaining; | |
289 | unsigned long size, offset, adjust; | |
290 | char *p, *modname; | |
291 | const char *name; | |
292 | int rc; | |
293 | ||
294 | /* | |
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). | |
299 | */ | |
300 | adjust = !kbt->new_context; | |
301 | address -= adjust; | |
302 | ||
303 | if (address >= PAGE_OFFSET) { | |
304 | /* Handle kernel symbols. */ | |
305 | BUG_ON(bufsize < KSYM_NAME_LEN); | |
306 | name = kallsyms_lookup(address, &size, &offset, | |
307 | &modname, buf); | |
308 | if (name == NULL) { | |
309 | buf[0] = '\0'; | |
310 | return; | |
311 | } | |
312 | namelen = strlen(buf); | |
313 | remaining = (bufsize - 1) - namelen; | |
314 | p = buf + 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'; | |
320 | return; | |
321 | } | |
322 | ||
323 | /* If we don't have the mmap_sem, we can't show any more info. */ | |
324 | buf[0] = '\0'; | |
325 | if (!have_mmap_sem) | |
326 | return; | |
327 | ||
328 | /* Find vma info. */ | |
329 | vma = find_vma(kbt->task->mm, address); | |
330 | if (vma == NULL || address < vma->vm_start) { | |
331 | snprintf(buf, bufsize, "[unmapped address] "); | |
332 | return; | |
333 | } | |
334 | ||
335 | if (vma->vm_file) { | |
9bf39ab2 | 336 | p = file_path(vma->vm_file, buf, bufsize); |
5f639fdc CM |
337 | if (IS_ERR(p)) |
338 | p = "?"; | |
0cc96a74 | 339 | name = kbasename(p); |
5f639fdc | 340 | } else { |
0cc96a74 | 341 | name = "anon"; |
5f639fdc CM |
342 | } |
343 | ||
344 | /* Generate a string description of the vma info. */ | |
0cc96a74 | 345 | namelen = strlen(name); |
5f639fdc | 346 | remaining = (bufsize - 1) - namelen; |
0cc96a74 | 347 | memmove(buf, name, namelen); |
5f639fdc CM |
348 | snprintf(buf + namelen, remaining, "[%lx+%lx] ", |
349 | vma->vm_start, vma->vm_end - vma->vm_start); | |
350 | } | |
351 | ||
3ef23111 CM |
352 | /* |
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. | |
356 | */ | |
357 | static bool start_backtrace(void) | |
358 | { | |
47ad7b9b | 359 | if (current_thread_info()->in_backtrace) { |
3ef23111 CM |
360 | pr_err("Backtrace requested while in backtrace!\n"); |
361 | return false; | |
362 | } | |
47ad7b9b | 363 | current_thread_info()->in_backtrace = true; |
3ef23111 CM |
364 | return true; |
365 | } | |
366 | ||
367 | static void end_backtrace(void) | |
368 | { | |
47ad7b9b | 369 | current_thread_info()->in_backtrace = false; |
3ef23111 CM |
370 | } |
371 | ||
867e359b CM |
372 | /* |
373 | * This method wraps the backtracer's more generic support. | |
374 | * It is only invoked from the architecture-specific code; show_stack() | |
47ad7b9b | 375 | * and dump_stack() are architecture-independent entry points. |
867e359b | 376 | */ |
47ad7b9b | 377 | void tile_show_stack(struct KBacktraceIterator *kbt) |
867e359b CM |
378 | { |
379 | int i; | |
5f639fdc | 380 | int have_mmap_sem = 0; |
867e359b | 381 | |
3ef23111 CM |
382 | if (!start_backtrace()) |
383 | return; | |
867e359b CM |
384 | kbt->verbose = 1; |
385 | i = 0; | |
386 | for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) { | |
867e359b | 387 | char namebuf[KSYM_NAME_LEN+100]; |
5f639fdc | 388 | unsigned long address = kbt->it.pc; |
867e359b | 389 | |
47ad7b9b CM |
390 | /* |
391 | * Try to acquire the mmap_sem as we pass into userspace. | |
392 | * If we're in an interrupt context, don't even try, since | |
393 | * it's not safe to call e.g. d_path() from an interrupt, | |
394 | * since it uses spin locks without disabling interrupts. | |
395 | * Note we test "kbt->task == current", not "kbt->is_current", | |
396 | * since we're checking that "current" will work in d_path(). | |
397 | */ | |
398 | if (kbt->task == current && address < PAGE_OFFSET && | |
399 | !have_mmap_sem && kbt->task->mm && !in_interrupt()) { | |
5f639fdc CM |
400 | have_mmap_sem = |
401 | down_read_trylock(&kbt->task->mm->mmap_sem); | |
47ad7b9b | 402 | } |
5f639fdc CM |
403 | |
404 | describe_addr(kbt, address, have_mmap_sem, | |
405 | namebuf, sizeof(namebuf)); | |
867e359b | 406 | |
0707ad30 | 407 | pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n", |
867e359b CM |
408 | i++, address, namebuf, (unsigned long)(kbt->it.sp)); |
409 | ||
410 | if (i >= 100) { | |
f4743673 | 411 | pr_err("Stack dump truncated (%d frames)\n", i); |
867e359b CM |
412 | break; |
413 | } | |
414 | } | |
dabe98c9 CM |
415 | if (kbt->end == KBT_LOOP) |
416 | pr_err("Stack dump stopped; next frame identical to this one\n"); | |
5f639fdc CM |
417 | if (have_mmap_sem) |
418 | up_read(&kbt->task->mm->mmap_sem); | |
3ef23111 | 419 | end_backtrace(); |
867e359b CM |
420 | } |
421 | EXPORT_SYMBOL(tile_show_stack); | |
422 | ||
867e359b CM |
423 | static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs, |
424 | ulong pc, ulong lr, ulong sp, ulong r52) | |
425 | { | |
426 | memset(regs, 0, sizeof(struct pt_regs)); | |
427 | regs->pc = pc; | |
428 | regs->lr = lr; | |
429 | regs->sp = sp; | |
430 | regs->regs[52] = r52; | |
431 | return regs; | |
432 | } | |
433 | ||
47ad7b9b | 434 | /* Deprecated function currently only used by kernel_double_fault(). */ |
867e359b CM |
435 | void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52) |
436 | { | |
47ad7b9b | 437 | struct KBacktraceIterator kbt; |
867e359b | 438 | struct pt_regs regs; |
47ad7b9b CM |
439 | |
440 | regs_to_pt_regs(®s, pc, lr, sp, r52); | |
441 | KBacktraceIterator_init(&kbt, NULL, ®s); | |
442 | tile_show_stack(&kbt); | |
867e359b CM |
443 | } |
444 | ||
445 | /* This is called from KBacktraceIterator_init_current() */ | |
446 | void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc, | |
447 | ulong lr, ulong sp, ulong r52) | |
448 | { | |
449 | struct pt_regs regs; | |
450 | KBacktraceIterator_init(kbt, NULL, | |
451 | regs_to_pt_regs(®s, pc, lr, sp, r52)); | |
452 | } | |
453 | ||
47ad7b9b CM |
454 | /* |
455 | * Called from sched_show_task() with task != NULL, or dump_stack() | |
456 | * with task == NULL. The esp argument is always NULL. | |
457 | */ | |
867e359b CM |
458 | void show_stack(struct task_struct *task, unsigned long *esp) |
459 | { | |
460 | struct KBacktraceIterator kbt; | |
47ad7b9b | 461 | if (task == NULL || task == current) { |
867e359b | 462 | KBacktraceIterator_init_current(&kbt); |
47ad7b9b CM |
463 | KBacktraceIterator_next(&kbt); /* don't show first frame */ |
464 | } else { | |
867e359b | 465 | KBacktraceIterator_init(&kbt, task, NULL); |
47ad7b9b CM |
466 | } |
467 | tile_show_stack(&kbt); | |
867e359b CM |
468 | } |
469 | ||
470 | #ifdef CONFIG_STACKTRACE | |
471 | ||
472 | /* Support generic Linux stack API too */ | |
473 | ||
47ad7b9b CM |
474 | static void save_stack_trace_common(struct task_struct *task, |
475 | struct pt_regs *regs, | |
476 | bool user, | |
477 | struct stack_trace *trace) | |
867e359b CM |
478 | { |
479 | struct KBacktraceIterator kbt; | |
480 | int skip = trace->skip; | |
481 | int i = 0; | |
482 | ||
3ef23111 CM |
483 | if (!start_backtrace()) |
484 | goto done; | |
47ad7b9b CM |
485 | if (regs != NULL) { |
486 | KBacktraceIterator_init(&kbt, NULL, regs); | |
487 | } else if (task == NULL || task == current) { | |
867e359b | 488 | KBacktraceIterator_init_current(&kbt); |
47ad7b9b CM |
489 | skip++; /* don't show KBacktraceIterator_init_current */ |
490 | } else { | |
867e359b | 491 | KBacktraceIterator_init(&kbt, task, NULL); |
47ad7b9b | 492 | } |
867e359b CM |
493 | for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) { |
494 | if (skip) { | |
495 | --skip; | |
496 | continue; | |
497 | } | |
47ad7b9b CM |
498 | if (i >= trace->max_entries || |
499 | (!user && kbt.it.pc < PAGE_OFFSET)) | |
867e359b CM |
500 | break; |
501 | trace->entries[i++] = kbt.it.pc; | |
502 | } | |
3ef23111 CM |
503 | end_backtrace(); |
504 | done: | |
47ad7b9b CM |
505 | if (i < trace->max_entries) |
506 | trace->entries[i++] = ULONG_MAX; | |
867e359b CM |
507 | trace->nr_entries = i; |
508 | } | |
47ad7b9b CM |
509 | |
510 | void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace) | |
511 | { | |
512 | save_stack_trace_common(task, NULL, false, trace); | |
513 | } | |
867e359b CM |
514 | EXPORT_SYMBOL(save_stack_trace_tsk); |
515 | ||
516 | void save_stack_trace(struct stack_trace *trace) | |
517 | { | |
47ad7b9b | 518 | save_stack_trace_common(NULL, NULL, false, trace); |
867e359b | 519 | } |
7c63e1ee | 520 | EXPORT_SYMBOL_GPL(save_stack_trace); |
867e359b | 521 | |
47ad7b9b CM |
522 | void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) |
523 | { | |
524 | save_stack_trace_common(NULL, regs, false, trace); | |
525 | } | |
526 | ||
527 | void save_stack_trace_user(struct stack_trace *trace) | |
528 | { | |
529 | /* Trace user stack if we are not a kernel thread. */ | |
530 | if (current->mm) | |
531 | save_stack_trace_common(NULL, task_pt_regs(current), | |
532 | true, trace); | |
533 | else if (trace->nr_entries < trace->max_entries) | |
534 | trace->entries[trace->nr_entries++] = ULONG_MAX; | |
535 | } | |
867e359b CM |
536 | #endif |
537 | ||
538 | /* In entry.S */ | |
539 | EXPORT_SYMBOL(KBacktraceIterator_init_current); |