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 AT |
33 | unsigned long stack_trace_max_size; |
34 | arch_spinlock_t max_stack_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 | |
68 | * data should be filled up, assuming max_stack_lock is held to | |
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 | ||
a5e25883 | 94 | local_irq_save(flags); |
0199c4e6 | 95 | arch_spin_lock(&max_stack_lock); |
e5a81b62 | 96 | |
4df29712 SRRH |
97 | /* In case another CPU set the tracer_frame on us */ |
98 | if (unlikely(!frame_size)) | |
99 | this_size -= tracer_frame; | |
100 | ||
e5a81b62 | 101 | /* a race could have already updated it */ |
bb99d8cc | 102 | if (this_size <= stack_trace_max_size) |
e5a81b62 SR |
103 | goto out; |
104 | ||
bb99d8cc | 105 | stack_trace_max_size = this_size; |
e5a81b62 | 106 | |
bb99d8cc AT |
107 | stack_trace_max.nr_entries = 0; |
108 | stack_trace_max.skip = 3; | |
e5a81b62 | 109 | |
bb99d8cc | 110 | save_stack_trace(&stack_trace_max); |
e5a81b62 | 111 | |
72ac426a | 112 | /* Skip over the overhead of the stack tracer itself */ |
bb99d8cc | 113 | for (i = 0; i < stack_trace_max.nr_entries; i++) { |
72ac426a SRRH |
114 | if (stack_dump_trace[i] == ip) |
115 | break; | |
116 | } | |
d4ecbfc4 | 117 | |
1b6cced6 SR |
118 | /* |
119 | * Now find where in the stack these are. | |
120 | */ | |
72ac426a | 121 | x = 0; |
87889501 | 122 | start = stack; |
1b6cced6 SR |
123 | top = (unsigned long *) |
124 | (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE); | |
125 | ||
126 | /* | |
127 | * Loop through all the entries. One of the entries may | |
128 | * for some reason be missed on the stack, so we may | |
129 | * have to account for them. If they are all there, this | |
130 | * loop will only happen once. This code only takes place | |
131 | * on a new max, so it is far from a fast path. | |
132 | */ | |
bb99d8cc | 133 | while (i < stack_trace_max.nr_entries) { |
0a37119d | 134 | int found = 0; |
1b6cced6 | 135 | |
bb99d8cc | 136 | stack_trace_index[x] = this_size; |
1b6cced6 SR |
137 | p = start; |
138 | ||
bb99d8cc | 139 | for (; p < top && i < stack_trace_max.nr_entries; p++) { |
72ac426a SRRH |
140 | if (stack_dump_trace[i] == ULONG_MAX) |
141 | break; | |
1b6cced6 | 142 | if (*p == stack_dump_trace[i]) { |
72ac426a | 143 | stack_dump_trace[x] = stack_dump_trace[i++]; |
bb99d8cc | 144 | this_size = stack_trace_index[x++] = |
1b6cced6 | 145 | (top - p) * sizeof(unsigned long); |
0a37119d | 146 | found = 1; |
1b6cced6 SR |
147 | /* Start the search from here */ |
148 | start = p + 1; | |
4df29712 SRRH |
149 | /* |
150 | * We do not want to show the overhead | |
151 | * of the stack tracer stack in the | |
152 | * max stack. If we haven't figured | |
153 | * out what that is, then figure it out | |
154 | * now. | |
155 | */ | |
72ac426a | 156 | if (unlikely(!tracer_frame)) { |
4df29712 SRRH |
157 | tracer_frame = (p - stack) * |
158 | sizeof(unsigned long); | |
bb99d8cc | 159 | stack_trace_max_size -= tracer_frame; |
4df29712 | 160 | } |
1b6cced6 SR |
161 | } |
162 | } | |
163 | ||
0a37119d SR |
164 | if (!found) |
165 | i++; | |
1b6cced6 SR |
166 | } |
167 | ||
bb99d8cc | 168 | stack_trace_max.nr_entries = x; |
72ac426a SRRH |
169 | for (; x < i; x++) |
170 | stack_dump_trace[x] = ULONG_MAX; | |
171 | ||
a70857e4 | 172 | if (task_stack_end_corrupted(current)) { |
bb99d8cc | 173 | stack_trace_print(); |
e3172181 MK |
174 | BUG(); |
175 | } | |
176 | ||
e5a81b62 | 177 | out: |
0199c4e6 | 178 | arch_spin_unlock(&max_stack_lock); |
a5e25883 | 179 | local_irq_restore(flags); |
e5a81b62 SR |
180 | } |
181 | ||
182 | static void | |
a1e2e31d SR |
183 | stack_trace_call(unsigned long ip, unsigned long parent_ip, |
184 | struct ftrace_ops *op, struct pt_regs *pt_regs) | |
e5a81b62 | 185 | { |
87889501 | 186 | unsigned long stack; |
5168ae50 | 187 | int cpu; |
e5a81b62 | 188 | |
5168ae50 | 189 | preempt_disable_notrace(); |
e5a81b62 SR |
190 | |
191 | cpu = raw_smp_processor_id(); | |
192 | /* no atomic needed, we only modify this variable by this cpu */ | |
193 | if (per_cpu(trace_active, cpu)++ != 0) | |
194 | goto out; | |
195 | ||
72ac426a | 196 | ip += MCOUNT_INSN_SIZE; |
4df29712 SRRH |
197 | |
198 | check_stack(ip, &stack); | |
e5a81b62 SR |
199 | |
200 | out: | |
201 | per_cpu(trace_active, cpu)--; | |
202 | /* prevent recursion in schedule */ | |
5168ae50 | 203 | preempt_enable_notrace(); |
e5a81b62 SR |
204 | } |
205 | ||
206 | static struct ftrace_ops trace_ops __read_mostly = | |
207 | { | |
208 | .func = stack_trace_call, | |
4740974a | 209 | .flags = FTRACE_OPS_FL_RECURSION_SAFE, |
e5a81b62 SR |
210 | }; |
211 | ||
212 | static ssize_t | |
213 | stack_max_size_read(struct file *filp, char __user *ubuf, | |
214 | size_t count, loff_t *ppos) | |
215 | { | |
216 | unsigned long *ptr = filp->private_data; | |
217 | char buf[64]; | |
218 | int r; | |
219 | ||
220 | r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); | |
221 | if (r > sizeof(buf)) | |
222 | r = sizeof(buf); | |
223 | return simple_read_from_buffer(ubuf, count, ppos, buf, r); | |
224 | } | |
225 | ||
226 | static ssize_t | |
227 | stack_max_size_write(struct file *filp, const char __user *ubuf, | |
228 | size_t count, loff_t *ppos) | |
229 | { | |
230 | long *ptr = filp->private_data; | |
231 | unsigned long val, flags; | |
e5a81b62 | 232 | int ret; |
4f48f8b7 | 233 | int cpu; |
e5a81b62 | 234 | |
22fe9b54 PH |
235 | ret = kstrtoul_from_user(ubuf, count, 10, &val); |
236 | if (ret) | |
e5a81b62 SR |
237 | return ret; |
238 | ||
a5e25883 | 239 | local_irq_save(flags); |
4f48f8b7 LJ |
240 | |
241 | /* | |
242 | * In case we trace inside arch_spin_lock() or after (NMI), | |
243 | * we will cause circular lock, so we also need to increase | |
244 | * the percpu trace_active here. | |
245 | */ | |
246 | cpu = smp_processor_id(); | |
247 | per_cpu(trace_active, cpu)++; | |
248 | ||
0199c4e6 | 249 | arch_spin_lock(&max_stack_lock); |
e5a81b62 | 250 | *ptr = val; |
0199c4e6 | 251 | arch_spin_unlock(&max_stack_lock); |
4f48f8b7 LJ |
252 | |
253 | per_cpu(trace_active, cpu)--; | |
a5e25883 | 254 | local_irq_restore(flags); |
e5a81b62 SR |
255 | |
256 | return count; | |
257 | } | |
258 | ||
f38f1d2a | 259 | static const struct file_operations stack_max_size_fops = { |
e5a81b62 SR |
260 | .open = tracing_open_generic, |
261 | .read = stack_max_size_read, | |
262 | .write = stack_max_size_write, | |
6038f373 | 263 | .llseek = default_llseek, |
e5a81b62 SR |
264 | }; |
265 | ||
266 | static void * | |
2fc5f0cf | 267 | __next(struct seq_file *m, loff_t *pos) |
e5a81b62 | 268 | { |
2fc5f0cf | 269 | long n = *pos - 1; |
e5a81b62 | 270 | |
bb99d8cc | 271 | if (n > stack_trace_max.nr_entries || stack_dump_trace[n] == ULONG_MAX) |
e5a81b62 SR |
272 | return NULL; |
273 | ||
2fc5f0cf | 274 | m->private = (void *)n; |
1b6cced6 | 275 | return &m->private; |
e5a81b62 SR |
276 | } |
277 | ||
2fc5f0cf LZ |
278 | static void * |
279 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
e5a81b62 | 280 | { |
2fc5f0cf LZ |
281 | (*pos)++; |
282 | return __next(m, pos); | |
283 | } | |
e5a81b62 | 284 | |
2fc5f0cf LZ |
285 | static void *t_start(struct seq_file *m, loff_t *pos) |
286 | { | |
4f48f8b7 LJ |
287 | int cpu; |
288 | ||
e5a81b62 | 289 | local_irq_disable(); |
4f48f8b7 LJ |
290 | |
291 | cpu = smp_processor_id(); | |
292 | per_cpu(trace_active, cpu)++; | |
293 | ||
0199c4e6 | 294 | arch_spin_lock(&max_stack_lock); |
e5a81b62 | 295 | |
522a110b LW |
296 | if (*pos == 0) |
297 | return SEQ_START_TOKEN; | |
298 | ||
2fc5f0cf | 299 | return __next(m, pos); |
e5a81b62 SR |
300 | } |
301 | ||
302 | static void t_stop(struct seq_file *m, void *p) | |
303 | { | |
4f48f8b7 LJ |
304 | int cpu; |
305 | ||
0199c4e6 | 306 | arch_spin_unlock(&max_stack_lock); |
4f48f8b7 LJ |
307 | |
308 | cpu = smp_processor_id(); | |
309 | per_cpu(trace_active, cpu)--; | |
310 | ||
e5a81b62 SR |
311 | local_irq_enable(); |
312 | } | |
313 | ||
962e3707 | 314 | static void trace_lookup_stack(struct seq_file *m, long i) |
e5a81b62 | 315 | { |
1b6cced6 | 316 | unsigned long addr = stack_dump_trace[i]; |
e5a81b62 | 317 | |
962e3707 | 318 | seq_printf(m, "%pS\n", (void *)addr); |
e5a81b62 SR |
319 | } |
320 | ||
e447e1df SR |
321 | static void print_disabled(struct seq_file *m) |
322 | { | |
323 | seq_puts(m, "#\n" | |
324 | "# Stack tracer disabled\n" | |
325 | "#\n" | |
326 | "# To enable the stack tracer, either add 'stacktrace' to the\n" | |
327 | "# kernel command line\n" | |
328 | "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n" | |
329 | "#\n"); | |
330 | } | |
331 | ||
e5a81b62 SR |
332 | static int t_show(struct seq_file *m, void *v) |
333 | { | |
522a110b | 334 | long i; |
1b6cced6 SR |
335 | int size; |
336 | ||
522a110b | 337 | if (v == SEQ_START_TOKEN) { |
eb1871f3 | 338 | seq_printf(m, " Depth Size Location" |
1b6cced6 | 339 | " (%d entries)\n" |
eb1871f3 | 340 | " ----- ---- --------\n", |
bb99d8cc | 341 | stack_trace_max.nr_entries); |
e447e1df | 342 | |
bb99d8cc | 343 | if (!stack_tracer_enabled && !stack_trace_max_size) |
e447e1df SR |
344 | print_disabled(m); |
345 | ||
1b6cced6 SR |
346 | return 0; |
347 | } | |
e5a81b62 | 348 | |
522a110b LW |
349 | i = *(long *)v; |
350 | ||
bb99d8cc | 351 | if (i >= stack_trace_max.nr_entries || |
1b6cced6 | 352 | stack_dump_trace[i] == ULONG_MAX) |
e5a81b62 SR |
353 | return 0; |
354 | ||
bb99d8cc | 355 | if (i+1 == stack_trace_max.nr_entries || |
1b6cced6 | 356 | stack_dump_trace[i+1] == ULONG_MAX) |
bb99d8cc | 357 | size = stack_trace_index[i]; |
1b6cced6 | 358 | else |
bb99d8cc | 359 | size = stack_trace_index[i] - stack_trace_index[i+1]; |
1b6cced6 | 360 | |
bb99d8cc | 361 | seq_printf(m, "%3ld) %8d %5d ", i, stack_trace_index[i], size); |
1b6cced6 SR |
362 | |
363 | trace_lookup_stack(m, i); | |
e5a81b62 SR |
364 | |
365 | return 0; | |
366 | } | |
367 | ||
f38f1d2a | 368 | static const struct seq_operations stack_trace_seq_ops = { |
e5a81b62 SR |
369 | .start = t_start, |
370 | .next = t_next, | |
371 | .stop = t_stop, | |
372 | .show = t_show, | |
373 | }; | |
374 | ||
375 | static int stack_trace_open(struct inode *inode, struct file *file) | |
376 | { | |
d8cc1ab7 | 377 | return seq_open(file, &stack_trace_seq_ops); |
e5a81b62 SR |
378 | } |
379 | ||
f38f1d2a | 380 | static const struct file_operations stack_trace_fops = { |
e5a81b62 SR |
381 | .open = stack_trace_open, |
382 | .read = seq_read, | |
383 | .llseek = seq_lseek, | |
d8cc1ab7 | 384 | .release = seq_release, |
e5a81b62 SR |
385 | }; |
386 | ||
d2d45c7a SR |
387 | static int |
388 | stack_trace_filter_open(struct inode *inode, struct file *file) | |
389 | { | |
390 | return ftrace_regex_open(&trace_ops, FTRACE_ITER_FILTER, | |
391 | inode, file); | |
392 | } | |
393 | ||
394 | static const struct file_operations stack_trace_filter_fops = { | |
395 | .open = stack_trace_filter_open, | |
396 | .read = seq_read, | |
397 | .write = ftrace_filter_write, | |
098c879e | 398 | .llseek = tracing_lseek, |
d2d45c7a SR |
399 | .release = ftrace_regex_release, |
400 | }; | |
401 | ||
f38f1d2a SR |
402 | int |
403 | stack_trace_sysctl(struct ctl_table *table, int write, | |
8d65af78 | 404 | void __user *buffer, size_t *lenp, |
f38f1d2a SR |
405 | loff_t *ppos) |
406 | { | |
407 | int ret; | |
408 | ||
409 | mutex_lock(&stack_sysctl_mutex); | |
410 | ||
8d65af78 | 411 | ret = proc_dointvec(table, write, buffer, lenp, ppos); |
f38f1d2a SR |
412 | |
413 | if (ret || !write || | |
a32c7765 | 414 | (last_stack_tracer_enabled == !!stack_tracer_enabled)) |
f38f1d2a SR |
415 | goto out; |
416 | ||
a32c7765 | 417 | last_stack_tracer_enabled = !!stack_tracer_enabled; |
f38f1d2a SR |
418 | |
419 | if (stack_tracer_enabled) | |
420 | register_ftrace_function(&trace_ops); | |
421 | else | |
422 | unregister_ftrace_function(&trace_ops); | |
423 | ||
424 | out: | |
425 | mutex_unlock(&stack_sysctl_mutex); | |
426 | return ret; | |
427 | } | |
428 | ||
762e1207 SR |
429 | static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata; |
430 | ||
f38f1d2a SR |
431 | static __init int enable_stacktrace(char *str) |
432 | { | |
762e1207 SR |
433 | if (strncmp(str, "_filter=", 8) == 0) |
434 | strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE); | |
435 | ||
e05a43b7 SR |
436 | stack_tracer_enabled = 1; |
437 | last_stack_tracer_enabled = 1; | |
f38f1d2a SR |
438 | return 1; |
439 | } | |
440 | __setup("stacktrace", enable_stacktrace); | |
441 | ||
e5a81b62 SR |
442 | static __init int stack_trace_init(void) |
443 | { | |
444 | struct dentry *d_tracer; | |
e5a81b62 SR |
445 | |
446 | d_tracer = tracing_init_dentry(); | |
14a5ae40 | 447 | if (IS_ERR(d_tracer)) |
ed6f1c99 | 448 | return 0; |
e5a81b62 | 449 | |
5452af66 | 450 | trace_create_file("stack_max_size", 0644, d_tracer, |
bb99d8cc | 451 | &stack_trace_max_size, &stack_max_size_fops); |
e5a81b62 | 452 | |
5452af66 FW |
453 | trace_create_file("stack_trace", 0444, d_tracer, |
454 | NULL, &stack_trace_fops); | |
e5a81b62 | 455 | |
d2d45c7a SR |
456 | trace_create_file("stack_trace_filter", 0444, d_tracer, |
457 | NULL, &stack_trace_filter_fops); | |
458 | ||
762e1207 SR |
459 | if (stack_trace_filter_buf[0]) |
460 | ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1); | |
461 | ||
e05a43b7 | 462 | if (stack_tracer_enabled) |
f38f1d2a | 463 | register_ftrace_function(&trace_ops); |
e5a81b62 SR |
464 | |
465 | return 0; | |
466 | } | |
467 | ||
468 | device_initcall(stack_trace_init); |