Commit | Line | Data |
---|---|---|
e5a81b62 SR |
1 | /* |
2 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
3 | * | |
4 | */ | |
5 | #include <linux/stacktrace.h> | |
6 | #include <linux/kallsyms.h> | |
7 | #include <linux/seq_file.h> | |
8 | #include <linux/spinlock.h> | |
9 | #include <linux/uaccess.h> | |
e5a81b62 SR |
10 | #include <linux/ftrace.h> |
11 | #include <linux/module.h> | |
f38f1d2a | 12 | #include <linux/sysctl.h> |
e5a81b62 | 13 | #include <linux/init.h> |
762e1207 SR |
14 | |
15 | #include <asm/setup.h> | |
16 | ||
e5a81b62 SR |
17 | #include "trace.h" |
18 | ||
1b6cced6 SR |
19 | static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] = |
20 | { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX }; | |
bb99d8cc | 21 | unsigned stack_trace_index[STACK_TRACE_ENTRIES]; |
1b6cced6 | 22 | |
4df29712 SRRH |
23 | /* |
24 | * Reserve one entry for the passed in ip. This will allow | |
25 | * us to remove most or all of the stack size overhead | |
26 | * added by the stack tracer itself. | |
27 | */ | |
bb99d8cc | 28 | struct stack_trace stack_trace_max = { |
4df29712 | 29 | .max_entries = STACK_TRACE_ENTRIES - 1, |
72ac426a | 30 | .entries = &stack_dump_trace[0], |
e5a81b62 SR |
31 | }; |
32 | ||
bb99d8cc | 33 | unsigned long stack_trace_max_size; |
d332736d | 34 | arch_spinlock_t stack_trace_max_lock = |
edc35bd7 | 35 | (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
e5a81b62 | 36 | |
e5a81b62 | 37 | static DEFINE_PER_CPU(int, trace_active); |
f38f1d2a SR |
38 | static DEFINE_MUTEX(stack_sysctl_mutex); |
39 | ||
40 | int stack_tracer_enabled; | |
41 | static int last_stack_tracer_enabled; | |
e5a81b62 | 42 | |
bb99d8cc | 43 | void stack_trace_print(void) |
e3172181 MK |
44 | { |
45 | long i; | |
46 | int size; | |
47 | ||
48 | pr_emerg(" Depth Size Location (%d entries)\n" | |
49 | " ----- ---- --------\n", | |
bb99d8cc | 50 | stack_trace_max.nr_entries); |
e3172181 | 51 | |
bb99d8cc | 52 | for (i = 0; i < stack_trace_max.nr_entries; i++) { |
e3172181 MK |
53 | if (stack_dump_trace[i] == ULONG_MAX) |
54 | break; | |
bb99d8cc | 55 | if (i+1 == stack_trace_max.nr_entries || |
e3172181 | 56 | stack_dump_trace[i+1] == ULONG_MAX) |
bb99d8cc | 57 | size = stack_trace_index[i]; |
e3172181 | 58 | else |
bb99d8cc | 59 | size = stack_trace_index[i] - stack_trace_index[i+1]; |
e3172181 | 60 | |
bb99d8cc | 61 | pr_emerg("%3ld) %8d %5d %pS\n", i, stack_trace_index[i], |
e3172181 MK |
62 | size, (void *)stack_dump_trace[i]); |
63 | } | |
64 | } | |
65 | ||
bb99d8cc AT |
66 | /* |
67 | * When arch-specific code overides this function, the following | |
d332736d | 68 | * data should be filled up, assuming stack_trace_max_lock is held to |
bb99d8cc AT |
69 | * prevent concurrent updates. |
70 | * stack_trace_index[] | |
71 | * stack_trace_max | |
72 | * stack_trace_max_size | |
73 | */ | |
74 | void __weak | |
d4ecbfc4 | 75 | check_stack(unsigned long ip, unsigned long *stack) |
e5a81b62 | 76 | { |
e3172181 | 77 | unsigned long this_size, flags; unsigned long *p, *top, *start; |
4df29712 SRRH |
78 | static int tracer_frame; |
79 | int frame_size = ACCESS_ONCE(tracer_frame); | |
72ac426a | 80 | int i, x; |
e5a81b62 | 81 | |
87889501 | 82 | this_size = ((unsigned long)stack) & (THREAD_SIZE-1); |
e5a81b62 | 83 | this_size = THREAD_SIZE - this_size; |
4df29712 SRRH |
84 | /* Remove the frame of the tracer */ |
85 | this_size -= frame_size; | |
e5a81b62 | 86 | |
bb99d8cc | 87 | if (this_size <= stack_trace_max_size) |
e5a81b62 SR |
88 | return; |
89 | ||
81520a1b | 90 | /* we do not handle interrupt stacks yet */ |
87889501 | 91 | if (!object_is_on_stack(stack)) |
81520a1b SR |
92 | return; |
93 | ||
1904be1b SRRH |
94 | /* Can't do this from NMI context (can cause deadlocks) */ |
95 | if (in_nmi()) | |
96 | return; | |
97 | ||
a5e25883 | 98 | local_irq_save(flags); |
d332736d | 99 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 100 | |
a2d76290 SRRH |
101 | /* |
102 | * RCU may not be watching, make it see us. | |
103 | * The stack trace code uses rcu_sched. | |
104 | */ | |
105 | rcu_irq_enter(); | |
106 | ||
4df29712 SRRH |
107 | /* In case another CPU set the tracer_frame on us */ |
108 | if (unlikely(!frame_size)) | |
109 | this_size -= tracer_frame; | |
110 | ||
e5a81b62 | 111 | /* a race could have already updated it */ |
bb99d8cc | 112 | if (this_size <= stack_trace_max_size) |
e5a81b62 SR |
113 | goto out; |
114 | ||
bb99d8cc | 115 | stack_trace_max_size = this_size; |
e5a81b62 | 116 | |
bb99d8cc AT |
117 | stack_trace_max.nr_entries = 0; |
118 | stack_trace_max.skip = 3; | |
e5a81b62 | 119 | |
bb99d8cc | 120 | save_stack_trace(&stack_trace_max); |
e5a81b62 | 121 | |
72ac426a | 122 | /* Skip over the overhead of the stack tracer itself */ |
bb99d8cc | 123 | for (i = 0; i < stack_trace_max.nr_entries; i++) { |
72ac426a SRRH |
124 | if (stack_dump_trace[i] == ip) |
125 | break; | |
126 | } | |
d4ecbfc4 | 127 | |
1b6cced6 SR |
128 | /* |
129 | * Now find where in the stack these are. | |
130 | */ | |
72ac426a | 131 | x = 0; |
87889501 | 132 | start = stack; |
1b6cced6 SR |
133 | top = (unsigned long *) |
134 | (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE); | |
135 | ||
136 | /* | |
137 | * Loop through all the entries. One of the entries may | |
138 | * for some reason be missed on the stack, so we may | |
139 | * have to account for them. If they are all there, this | |
140 | * loop will only happen once. This code only takes place | |
141 | * on a new max, so it is far from a fast path. | |
142 | */ | |
bb99d8cc | 143 | while (i < stack_trace_max.nr_entries) { |
0a37119d | 144 | int found = 0; |
1b6cced6 | 145 | |
bb99d8cc | 146 | stack_trace_index[x] = this_size; |
1b6cced6 SR |
147 | p = start; |
148 | ||
bb99d8cc | 149 | for (; p < top && i < stack_trace_max.nr_entries; p++) { |
72ac426a SRRH |
150 | if (stack_dump_trace[i] == ULONG_MAX) |
151 | break; | |
1b6cced6 | 152 | if (*p == stack_dump_trace[i]) { |
72ac426a | 153 | stack_dump_trace[x] = stack_dump_trace[i++]; |
bb99d8cc | 154 | this_size = stack_trace_index[x++] = |
1b6cced6 | 155 | (top - p) * sizeof(unsigned long); |
0a37119d | 156 | found = 1; |
1b6cced6 SR |
157 | /* Start the search from here */ |
158 | start = p + 1; | |
4df29712 SRRH |
159 | /* |
160 | * We do not want to show the overhead | |
161 | * of the stack tracer stack in the | |
162 | * max stack. If we haven't figured | |
163 | * out what that is, then figure it out | |
164 | * now. | |
165 | */ | |
72ac426a | 166 | if (unlikely(!tracer_frame)) { |
4df29712 SRRH |
167 | tracer_frame = (p - stack) * |
168 | sizeof(unsigned long); | |
bb99d8cc | 169 | stack_trace_max_size -= tracer_frame; |
4df29712 | 170 | } |
1b6cced6 SR |
171 | } |
172 | } | |
173 | ||
0a37119d SR |
174 | if (!found) |
175 | i++; | |
1b6cced6 SR |
176 | } |
177 | ||
bb99d8cc | 178 | stack_trace_max.nr_entries = x; |
72ac426a SRRH |
179 | for (; x < i; x++) |
180 | stack_dump_trace[x] = ULONG_MAX; | |
181 | ||
a70857e4 | 182 | if (task_stack_end_corrupted(current)) { |
bb99d8cc | 183 | stack_trace_print(); |
e3172181 MK |
184 | BUG(); |
185 | } | |
186 | ||
e5a81b62 | 187 | out: |
a2d76290 | 188 | rcu_irq_exit(); |
d332736d | 189 | arch_spin_unlock(&stack_trace_max_lock); |
a5e25883 | 190 | local_irq_restore(flags); |
e5a81b62 SR |
191 | } |
192 | ||
193 | static void | |
a1e2e31d SR |
194 | stack_trace_call(unsigned long ip, unsigned long parent_ip, |
195 | struct ftrace_ops *op, struct pt_regs *pt_regs) | |
e5a81b62 | 196 | { |
87889501 | 197 | unsigned long stack; |
5168ae50 | 198 | int cpu; |
e5a81b62 | 199 | |
5168ae50 | 200 | preempt_disable_notrace(); |
e5a81b62 SR |
201 | |
202 | cpu = raw_smp_processor_id(); | |
203 | /* no atomic needed, we only modify this variable by this cpu */ | |
204 | if (per_cpu(trace_active, cpu)++ != 0) | |
205 | goto out; | |
206 | ||
72ac426a | 207 | ip += MCOUNT_INSN_SIZE; |
4df29712 SRRH |
208 | |
209 | check_stack(ip, &stack); | |
e5a81b62 SR |
210 | |
211 | out: | |
212 | per_cpu(trace_active, cpu)--; | |
213 | /* prevent recursion in schedule */ | |
5168ae50 | 214 | preempt_enable_notrace(); |
e5a81b62 SR |
215 | } |
216 | ||
217 | static struct ftrace_ops trace_ops __read_mostly = | |
218 | { | |
219 | .func = stack_trace_call, | |
4740974a | 220 | .flags = FTRACE_OPS_FL_RECURSION_SAFE, |
e5a81b62 SR |
221 | }; |
222 | ||
223 | static ssize_t | |
224 | stack_max_size_read(struct file *filp, char __user *ubuf, | |
225 | size_t count, loff_t *ppos) | |
226 | { | |
227 | unsigned long *ptr = filp->private_data; | |
228 | char buf[64]; | |
229 | int r; | |
230 | ||
231 | r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); | |
232 | if (r > sizeof(buf)) | |
233 | r = sizeof(buf); | |
234 | return simple_read_from_buffer(ubuf, count, ppos, buf, r); | |
235 | } | |
236 | ||
237 | static ssize_t | |
238 | stack_max_size_write(struct file *filp, const char __user *ubuf, | |
239 | size_t count, loff_t *ppos) | |
240 | { | |
241 | long *ptr = filp->private_data; | |
242 | unsigned long val, flags; | |
e5a81b62 | 243 | int ret; |
4f48f8b7 | 244 | int cpu; |
e5a81b62 | 245 | |
22fe9b54 PH |
246 | ret = kstrtoul_from_user(ubuf, count, 10, &val); |
247 | if (ret) | |
e5a81b62 SR |
248 | return ret; |
249 | ||
a5e25883 | 250 | local_irq_save(flags); |
4f48f8b7 LJ |
251 | |
252 | /* | |
253 | * In case we trace inside arch_spin_lock() or after (NMI), | |
254 | * we will cause circular lock, so we also need to increase | |
255 | * the percpu trace_active here. | |
256 | */ | |
257 | cpu = smp_processor_id(); | |
258 | per_cpu(trace_active, cpu)++; | |
259 | ||
d332736d | 260 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 261 | *ptr = val; |
d332736d | 262 | arch_spin_unlock(&stack_trace_max_lock); |
4f48f8b7 LJ |
263 | |
264 | per_cpu(trace_active, cpu)--; | |
a5e25883 | 265 | local_irq_restore(flags); |
e5a81b62 SR |
266 | |
267 | return count; | |
268 | } | |
269 | ||
f38f1d2a | 270 | static const struct file_operations stack_max_size_fops = { |
e5a81b62 SR |
271 | .open = tracing_open_generic, |
272 | .read = stack_max_size_read, | |
273 | .write = stack_max_size_write, | |
6038f373 | 274 | .llseek = default_llseek, |
e5a81b62 SR |
275 | }; |
276 | ||
277 | static void * | |
2fc5f0cf | 278 | __next(struct seq_file *m, loff_t *pos) |
e5a81b62 | 279 | { |
2fc5f0cf | 280 | long n = *pos - 1; |
e5a81b62 | 281 | |
bb99d8cc | 282 | if (n > stack_trace_max.nr_entries || stack_dump_trace[n] == ULONG_MAX) |
e5a81b62 SR |
283 | return NULL; |
284 | ||
2fc5f0cf | 285 | m->private = (void *)n; |
1b6cced6 | 286 | return &m->private; |
e5a81b62 SR |
287 | } |
288 | ||
2fc5f0cf LZ |
289 | static void * |
290 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
e5a81b62 | 291 | { |
2fc5f0cf LZ |
292 | (*pos)++; |
293 | return __next(m, pos); | |
294 | } | |
e5a81b62 | 295 | |
2fc5f0cf LZ |
296 | static void *t_start(struct seq_file *m, loff_t *pos) |
297 | { | |
4f48f8b7 LJ |
298 | int cpu; |
299 | ||
e5a81b62 | 300 | local_irq_disable(); |
4f48f8b7 LJ |
301 | |
302 | cpu = smp_processor_id(); | |
303 | per_cpu(trace_active, cpu)++; | |
304 | ||
d332736d | 305 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 306 | |
522a110b LW |
307 | if (*pos == 0) |
308 | return SEQ_START_TOKEN; | |
309 | ||
2fc5f0cf | 310 | return __next(m, pos); |
e5a81b62 SR |
311 | } |
312 | ||
313 | static void t_stop(struct seq_file *m, void *p) | |
314 | { | |
4f48f8b7 LJ |
315 | int cpu; |
316 | ||
d332736d | 317 | arch_spin_unlock(&stack_trace_max_lock); |
4f48f8b7 LJ |
318 | |
319 | cpu = smp_processor_id(); | |
320 | per_cpu(trace_active, cpu)--; | |
321 | ||
e5a81b62 SR |
322 | local_irq_enable(); |
323 | } | |
324 | ||
962e3707 | 325 | static void trace_lookup_stack(struct seq_file *m, long i) |
e5a81b62 | 326 | { |
1b6cced6 | 327 | unsigned long addr = stack_dump_trace[i]; |
e5a81b62 | 328 | |
962e3707 | 329 | seq_printf(m, "%pS\n", (void *)addr); |
e5a81b62 SR |
330 | } |
331 | ||
e447e1df SR |
332 | static void print_disabled(struct seq_file *m) |
333 | { | |
334 | seq_puts(m, "#\n" | |
335 | "# Stack tracer disabled\n" | |
336 | "#\n" | |
337 | "# To enable the stack tracer, either add 'stacktrace' to the\n" | |
338 | "# kernel command line\n" | |
339 | "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n" | |
340 | "#\n"); | |
341 | } | |
342 | ||
e5a81b62 SR |
343 | static int t_show(struct seq_file *m, void *v) |
344 | { | |
522a110b | 345 | long i; |
1b6cced6 SR |
346 | int size; |
347 | ||
522a110b | 348 | if (v == SEQ_START_TOKEN) { |
eb1871f3 | 349 | seq_printf(m, " Depth Size Location" |
1b6cced6 | 350 | " (%d entries)\n" |
eb1871f3 | 351 | " ----- ---- --------\n", |
bb99d8cc | 352 | stack_trace_max.nr_entries); |
e447e1df | 353 | |
bb99d8cc | 354 | if (!stack_tracer_enabled && !stack_trace_max_size) |
e447e1df SR |
355 | print_disabled(m); |
356 | ||
1b6cced6 SR |
357 | return 0; |
358 | } | |
e5a81b62 | 359 | |
522a110b LW |
360 | i = *(long *)v; |
361 | ||
bb99d8cc | 362 | if (i >= stack_trace_max.nr_entries || |
1b6cced6 | 363 | stack_dump_trace[i] == ULONG_MAX) |
e5a81b62 SR |
364 | return 0; |
365 | ||
bb99d8cc | 366 | if (i+1 == stack_trace_max.nr_entries || |
1b6cced6 | 367 | stack_dump_trace[i+1] == ULONG_MAX) |
bb99d8cc | 368 | size = stack_trace_index[i]; |
1b6cced6 | 369 | else |
bb99d8cc | 370 | size = stack_trace_index[i] - stack_trace_index[i+1]; |
1b6cced6 | 371 | |
bb99d8cc | 372 | seq_printf(m, "%3ld) %8d %5d ", i, stack_trace_index[i], size); |
1b6cced6 SR |
373 | |
374 | trace_lookup_stack(m, i); | |
e5a81b62 SR |
375 | |
376 | return 0; | |
377 | } | |
378 | ||
f38f1d2a | 379 | static const struct seq_operations stack_trace_seq_ops = { |
e5a81b62 SR |
380 | .start = t_start, |
381 | .next = t_next, | |
382 | .stop = t_stop, | |
383 | .show = t_show, | |
384 | }; | |
385 | ||
386 | static int stack_trace_open(struct inode *inode, struct file *file) | |
387 | { | |
d8cc1ab7 | 388 | return seq_open(file, &stack_trace_seq_ops); |
e5a81b62 SR |
389 | } |
390 | ||
f38f1d2a | 391 | static const struct file_operations stack_trace_fops = { |
e5a81b62 SR |
392 | .open = stack_trace_open, |
393 | .read = seq_read, | |
394 | .llseek = seq_lseek, | |
d8cc1ab7 | 395 | .release = seq_release, |
e5a81b62 SR |
396 | }; |
397 | ||
d2d45c7a SR |
398 | static int |
399 | stack_trace_filter_open(struct inode *inode, struct file *file) | |
400 | { | |
401 | return ftrace_regex_open(&trace_ops, FTRACE_ITER_FILTER, | |
402 | inode, file); | |
403 | } | |
404 | ||
405 | static const struct file_operations stack_trace_filter_fops = { | |
406 | .open = stack_trace_filter_open, | |
407 | .read = seq_read, | |
408 | .write = ftrace_filter_write, | |
098c879e | 409 | .llseek = tracing_lseek, |
d2d45c7a SR |
410 | .release = ftrace_regex_release, |
411 | }; | |
412 | ||
f38f1d2a SR |
413 | int |
414 | stack_trace_sysctl(struct ctl_table *table, int write, | |
8d65af78 | 415 | void __user *buffer, size_t *lenp, |
f38f1d2a SR |
416 | loff_t *ppos) |
417 | { | |
418 | int ret; | |
419 | ||
420 | mutex_lock(&stack_sysctl_mutex); | |
421 | ||
8d65af78 | 422 | ret = proc_dointvec(table, write, buffer, lenp, ppos); |
f38f1d2a SR |
423 | |
424 | if (ret || !write || | |
a32c7765 | 425 | (last_stack_tracer_enabled == !!stack_tracer_enabled)) |
f38f1d2a SR |
426 | goto out; |
427 | ||
a32c7765 | 428 | last_stack_tracer_enabled = !!stack_tracer_enabled; |
f38f1d2a SR |
429 | |
430 | if (stack_tracer_enabled) | |
431 | register_ftrace_function(&trace_ops); | |
432 | else | |
433 | unregister_ftrace_function(&trace_ops); | |
434 | ||
435 | out: | |
436 | mutex_unlock(&stack_sysctl_mutex); | |
437 | return ret; | |
438 | } | |
439 | ||
762e1207 SR |
440 | static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata; |
441 | ||
f38f1d2a SR |
442 | static __init int enable_stacktrace(char *str) |
443 | { | |
762e1207 SR |
444 | if (strncmp(str, "_filter=", 8) == 0) |
445 | strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE); | |
446 | ||
e05a43b7 SR |
447 | stack_tracer_enabled = 1; |
448 | last_stack_tracer_enabled = 1; | |
f38f1d2a SR |
449 | return 1; |
450 | } | |
451 | __setup("stacktrace", enable_stacktrace); | |
452 | ||
e5a81b62 SR |
453 | static __init int stack_trace_init(void) |
454 | { | |
455 | struct dentry *d_tracer; | |
e5a81b62 SR |
456 | |
457 | d_tracer = tracing_init_dentry(); | |
14a5ae40 | 458 | if (IS_ERR(d_tracer)) |
ed6f1c99 | 459 | return 0; |
e5a81b62 | 460 | |
5452af66 | 461 | trace_create_file("stack_max_size", 0644, d_tracer, |
bb99d8cc | 462 | &stack_trace_max_size, &stack_max_size_fops); |
e5a81b62 | 463 | |
5452af66 FW |
464 | trace_create_file("stack_trace", 0444, d_tracer, |
465 | NULL, &stack_trace_fops); | |
e5a81b62 | 466 | |
d2d45c7a SR |
467 | trace_create_file("stack_trace_filter", 0444, d_tracer, |
468 | NULL, &stack_trace_filter_fops); | |
469 | ||
762e1207 SR |
470 | if (stack_trace_filter_buf[0]) |
471 | ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1); | |
472 | ||
e05a43b7 | 473 | if (stack_tracer_enabled) |
f38f1d2a | 474 | register_ftrace_function(&trace_ops); |
e5a81b62 SR |
475 | |
476 | return 0; | |
477 | } | |
478 | ||
479 | device_initcall(stack_trace_init); |