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> | |
10 | #include <linux/debugfs.h> | |
11 | #include <linux/ftrace.h> | |
12 | #include <linux/module.h> | |
f38f1d2a | 13 | #include <linux/sysctl.h> |
e5a81b62 SR |
14 | #include <linux/init.h> |
15 | #include <linux/fs.h> | |
762e1207 SR |
16 | |
17 | #include <asm/setup.h> | |
18 | ||
e5a81b62 SR |
19 | #include "trace.h" |
20 | ||
21 | #define STACK_TRACE_ENTRIES 500 | |
22 | ||
d4ecbfc4 | 23 | #ifdef CC_USING_FENTRY |
4df29712 | 24 | # define fentry 1 |
d4ecbfc4 | 25 | #else |
4df29712 | 26 | # define fentry 0 |
d4ecbfc4 SRRH |
27 | #endif |
28 | ||
1b6cced6 SR |
29 | static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] = |
30 | { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX }; | |
31 | static unsigned stack_dump_index[STACK_TRACE_ENTRIES]; | |
32 | ||
4df29712 SRRH |
33 | /* |
34 | * Reserve one entry for the passed in ip. This will allow | |
35 | * us to remove most or all of the stack size overhead | |
36 | * added by the stack tracer itself. | |
37 | */ | |
e5a81b62 | 38 | static struct stack_trace max_stack_trace = { |
4df29712 SRRH |
39 | .max_entries = STACK_TRACE_ENTRIES - 1, |
40 | .entries = &stack_dump_trace[1], | |
e5a81b62 SR |
41 | }; |
42 | ||
43 | static unsigned long max_stack_size; | |
445c8951 | 44 | static arch_spinlock_t max_stack_lock = |
edc35bd7 | 45 | (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
e5a81b62 | 46 | |
e5a81b62 | 47 | static DEFINE_PER_CPU(int, trace_active); |
f38f1d2a SR |
48 | static DEFINE_MUTEX(stack_sysctl_mutex); |
49 | ||
50 | int stack_tracer_enabled; | |
51 | static int last_stack_tracer_enabled; | |
e5a81b62 | 52 | |
e3172181 MK |
53 | static inline void print_max_stack(void) |
54 | { | |
55 | long i; | |
56 | int size; | |
57 | ||
58 | pr_emerg(" Depth Size Location (%d entries)\n" | |
59 | " ----- ---- --------\n", | |
60 | max_stack_trace.nr_entries - 1); | |
61 | ||
62 | for (i = 0; i < max_stack_trace.nr_entries; i++) { | |
63 | if (stack_dump_trace[i] == ULONG_MAX) | |
64 | break; | |
65 | if (i+1 == max_stack_trace.nr_entries || | |
66 | stack_dump_trace[i+1] == ULONG_MAX) | |
67 | size = stack_dump_index[i]; | |
68 | else | |
69 | size = stack_dump_index[i] - stack_dump_index[i+1]; | |
70 | ||
71 | pr_emerg("%3ld) %8d %5d %pS\n", i, stack_dump_index[i], | |
72 | size, (void *)stack_dump_trace[i]); | |
73 | } | |
74 | } | |
75 | ||
87889501 | 76 | static inline void |
d4ecbfc4 | 77 | check_stack(unsigned long ip, unsigned long *stack) |
e5a81b62 | 78 | { |
e3172181 | 79 | unsigned long this_size, flags; unsigned long *p, *top, *start; |
4df29712 SRRH |
80 | static int tracer_frame; |
81 | int frame_size = ACCESS_ONCE(tracer_frame); | |
1b6cced6 | 82 | int i; |
e5a81b62 | 83 | |
87889501 | 84 | this_size = ((unsigned long)stack) & (THREAD_SIZE-1); |
e5a81b62 | 85 | this_size = THREAD_SIZE - this_size; |
4df29712 SRRH |
86 | /* Remove the frame of the tracer */ |
87 | this_size -= frame_size; | |
e5a81b62 SR |
88 | |
89 | if (this_size <= max_stack_size) | |
90 | return; | |
91 | ||
81520a1b | 92 | /* we do not handle interrupt stacks yet */ |
87889501 | 93 | if (!object_is_on_stack(stack)) |
81520a1b SR |
94 | return; |
95 | ||
a5e25883 | 96 | local_irq_save(flags); |
0199c4e6 | 97 | arch_spin_lock(&max_stack_lock); |
e5a81b62 | 98 | |
4df29712 SRRH |
99 | /* In case another CPU set the tracer_frame on us */ |
100 | if (unlikely(!frame_size)) | |
101 | this_size -= tracer_frame; | |
102 | ||
e5a81b62 SR |
103 | /* a race could have already updated it */ |
104 | if (this_size <= max_stack_size) | |
105 | goto out; | |
106 | ||
107 | max_stack_size = this_size; | |
108 | ||
7eea4fce JW |
109 | max_stack_trace.nr_entries = 0; |
110 | ||
111 | if (using_ftrace_ops_list_func()) | |
112 | max_stack_trace.skip = 4; | |
113 | else | |
114 | max_stack_trace.skip = 3; | |
e5a81b62 SR |
115 | |
116 | save_stack_trace(&max_stack_trace); | |
117 | ||
d4ecbfc4 | 118 | /* |
4df29712 SRRH |
119 | * Add the passed in ip from the function tracer. |
120 | * Searching for this on the stack will skip over | |
121 | * most of the overhead from the stack tracer itself. | |
d4ecbfc4 | 122 | */ |
4df29712 SRRH |
123 | stack_dump_trace[0] = ip; |
124 | max_stack_trace.nr_entries++; | |
d4ecbfc4 | 125 | |
1b6cced6 SR |
126 | /* |
127 | * Now find where in the stack these are. | |
128 | */ | |
129 | i = 0; | |
87889501 | 130 | start = stack; |
1b6cced6 SR |
131 | top = (unsigned long *) |
132 | (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE); | |
133 | ||
134 | /* | |
135 | * Loop through all the entries. One of the entries may | |
136 | * for some reason be missed on the stack, so we may | |
137 | * have to account for them. If they are all there, this | |
138 | * loop will only happen once. This code only takes place | |
139 | * on a new max, so it is far from a fast path. | |
140 | */ | |
141 | while (i < max_stack_trace.nr_entries) { | |
0a37119d | 142 | int found = 0; |
1b6cced6 SR |
143 | |
144 | stack_dump_index[i] = this_size; | |
145 | p = start; | |
146 | ||
147 | for (; p < top && i < max_stack_trace.nr_entries; p++) { | |
148 | if (*p == stack_dump_trace[i]) { | |
149 | this_size = stack_dump_index[i++] = | |
150 | (top - p) * sizeof(unsigned long); | |
0a37119d | 151 | found = 1; |
1b6cced6 SR |
152 | /* Start the search from here */ |
153 | start = p + 1; | |
4df29712 SRRH |
154 | /* |
155 | * We do not want to show the overhead | |
156 | * of the stack tracer stack in the | |
157 | * max stack. If we haven't figured | |
158 | * out what that is, then figure it out | |
159 | * now. | |
160 | */ | |
161 | if (unlikely(!tracer_frame) && i == 1) { | |
162 | tracer_frame = (p - stack) * | |
163 | sizeof(unsigned long); | |
164 | max_stack_size -= tracer_frame; | |
165 | } | |
1b6cced6 SR |
166 | } |
167 | } | |
168 | ||
0a37119d SR |
169 | if (!found) |
170 | i++; | |
1b6cced6 SR |
171 | } |
172 | ||
a70857e4 | 173 | if (task_stack_end_corrupted(current)) { |
e3172181 MK |
174 | print_max_stack(); |
175 | BUG(); | |
176 | } | |
177 | ||
e5a81b62 | 178 | out: |
0199c4e6 | 179 | arch_spin_unlock(&max_stack_lock); |
a5e25883 | 180 | local_irq_restore(flags); |
e5a81b62 SR |
181 | } |
182 | ||
183 | static void | |
a1e2e31d SR |
184 | stack_trace_call(unsigned long ip, unsigned long parent_ip, |
185 | struct ftrace_ops *op, struct pt_regs *pt_regs) | |
e5a81b62 | 186 | { |
87889501 | 187 | unsigned long stack; |
5168ae50 | 188 | int cpu; |
e5a81b62 | 189 | |
5168ae50 | 190 | preempt_disable_notrace(); |
e5a81b62 SR |
191 | |
192 | cpu = raw_smp_processor_id(); | |
193 | /* no atomic needed, we only modify this variable by this cpu */ | |
194 | if (per_cpu(trace_active, cpu)++ != 0) | |
195 | goto out; | |
196 | ||
4df29712 SRRH |
197 | /* |
198 | * When fentry is used, the traced function does not get | |
199 | * its stack frame set up, and we lose the parent. | |
200 | * The ip is pretty useless because the function tracer | |
201 | * was called before that function set up its stack frame. | |
202 | * In this case, we use the parent ip. | |
203 | * | |
204 | * By adding the return address of either the parent ip | |
205 | * or the current ip we can disregard most of the stack usage | |
206 | * caused by the stack tracer itself. | |
207 | * | |
208 | * The function tracer always reports the address of where the | |
209 | * mcount call was, but the stack will hold the return address. | |
210 | */ | |
211 | if (fentry) | |
212 | ip = parent_ip; | |
213 | else | |
214 | ip += MCOUNT_INSN_SIZE; | |
215 | ||
216 | check_stack(ip, &stack); | |
e5a81b62 SR |
217 | |
218 | out: | |
219 | per_cpu(trace_active, cpu)--; | |
220 | /* prevent recursion in schedule */ | |
5168ae50 | 221 | preempt_enable_notrace(); |
e5a81b62 SR |
222 | } |
223 | ||
224 | static struct ftrace_ops trace_ops __read_mostly = | |
225 | { | |
226 | .func = stack_trace_call, | |
4740974a | 227 | .flags = FTRACE_OPS_FL_RECURSION_SAFE, |
e5a81b62 SR |
228 | }; |
229 | ||
230 | static ssize_t | |
231 | stack_max_size_read(struct file *filp, char __user *ubuf, | |
232 | size_t count, loff_t *ppos) | |
233 | { | |
234 | unsigned long *ptr = filp->private_data; | |
235 | char buf[64]; | |
236 | int r; | |
237 | ||
238 | r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); | |
239 | if (r > sizeof(buf)) | |
240 | r = sizeof(buf); | |
241 | return simple_read_from_buffer(ubuf, count, ppos, buf, r); | |
242 | } | |
243 | ||
244 | static ssize_t | |
245 | stack_max_size_write(struct file *filp, const char __user *ubuf, | |
246 | size_t count, loff_t *ppos) | |
247 | { | |
248 | long *ptr = filp->private_data; | |
249 | unsigned long val, flags; | |
e5a81b62 | 250 | int ret; |
4f48f8b7 | 251 | int cpu; |
e5a81b62 | 252 | |
22fe9b54 PH |
253 | ret = kstrtoul_from_user(ubuf, count, 10, &val); |
254 | if (ret) | |
e5a81b62 SR |
255 | return ret; |
256 | ||
a5e25883 | 257 | local_irq_save(flags); |
4f48f8b7 LJ |
258 | |
259 | /* | |
260 | * In case we trace inside arch_spin_lock() or after (NMI), | |
261 | * we will cause circular lock, so we also need to increase | |
262 | * the percpu trace_active here. | |
263 | */ | |
264 | cpu = smp_processor_id(); | |
265 | per_cpu(trace_active, cpu)++; | |
266 | ||
0199c4e6 | 267 | arch_spin_lock(&max_stack_lock); |
e5a81b62 | 268 | *ptr = val; |
0199c4e6 | 269 | arch_spin_unlock(&max_stack_lock); |
4f48f8b7 LJ |
270 | |
271 | per_cpu(trace_active, cpu)--; | |
a5e25883 | 272 | local_irq_restore(flags); |
e5a81b62 SR |
273 | |
274 | return count; | |
275 | } | |
276 | ||
f38f1d2a | 277 | static const struct file_operations stack_max_size_fops = { |
e5a81b62 SR |
278 | .open = tracing_open_generic, |
279 | .read = stack_max_size_read, | |
280 | .write = stack_max_size_write, | |
6038f373 | 281 | .llseek = default_llseek, |
e5a81b62 SR |
282 | }; |
283 | ||
284 | static void * | |
2fc5f0cf | 285 | __next(struct seq_file *m, loff_t *pos) |
e5a81b62 | 286 | { |
2fc5f0cf | 287 | long n = *pos - 1; |
e5a81b62 | 288 | |
2fc5f0cf | 289 | if (n >= max_stack_trace.nr_entries || stack_dump_trace[n] == ULONG_MAX) |
e5a81b62 SR |
290 | return NULL; |
291 | ||
2fc5f0cf | 292 | m->private = (void *)n; |
1b6cced6 | 293 | return &m->private; |
e5a81b62 SR |
294 | } |
295 | ||
2fc5f0cf LZ |
296 | static void * |
297 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
e5a81b62 | 298 | { |
2fc5f0cf LZ |
299 | (*pos)++; |
300 | return __next(m, pos); | |
301 | } | |
e5a81b62 | 302 | |
2fc5f0cf LZ |
303 | static void *t_start(struct seq_file *m, loff_t *pos) |
304 | { | |
4f48f8b7 LJ |
305 | int cpu; |
306 | ||
e5a81b62 | 307 | local_irq_disable(); |
4f48f8b7 LJ |
308 | |
309 | cpu = smp_processor_id(); | |
310 | per_cpu(trace_active, cpu)++; | |
311 | ||
0199c4e6 | 312 | arch_spin_lock(&max_stack_lock); |
e5a81b62 | 313 | |
522a110b LW |
314 | if (*pos == 0) |
315 | return SEQ_START_TOKEN; | |
316 | ||
2fc5f0cf | 317 | return __next(m, pos); |
e5a81b62 SR |
318 | } |
319 | ||
320 | static void t_stop(struct seq_file *m, void *p) | |
321 | { | |
4f48f8b7 LJ |
322 | int cpu; |
323 | ||
0199c4e6 | 324 | arch_spin_unlock(&max_stack_lock); |
4f48f8b7 LJ |
325 | |
326 | cpu = smp_processor_id(); | |
327 | per_cpu(trace_active, cpu)--; | |
328 | ||
e5a81b62 SR |
329 | local_irq_enable(); |
330 | } | |
331 | ||
1b6cced6 | 332 | static int trace_lookup_stack(struct seq_file *m, long i) |
e5a81b62 | 333 | { |
1b6cced6 | 334 | unsigned long addr = stack_dump_trace[i]; |
e5a81b62 | 335 | |
151772db | 336 | return seq_printf(m, "%pS\n", (void *)addr); |
e5a81b62 SR |
337 | } |
338 | ||
e447e1df SR |
339 | static void print_disabled(struct seq_file *m) |
340 | { | |
341 | seq_puts(m, "#\n" | |
342 | "# Stack tracer disabled\n" | |
343 | "#\n" | |
344 | "# To enable the stack tracer, either add 'stacktrace' to the\n" | |
345 | "# kernel command line\n" | |
346 | "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n" | |
347 | "#\n"); | |
348 | } | |
349 | ||
e5a81b62 SR |
350 | static int t_show(struct seq_file *m, void *v) |
351 | { | |
522a110b | 352 | long i; |
1b6cced6 SR |
353 | int size; |
354 | ||
522a110b | 355 | if (v == SEQ_START_TOKEN) { |
eb1871f3 | 356 | seq_printf(m, " Depth Size Location" |
1b6cced6 | 357 | " (%d entries)\n" |
eb1871f3 | 358 | " ----- ---- --------\n", |
083a63b4 | 359 | max_stack_trace.nr_entries - 1); |
e447e1df SR |
360 | |
361 | if (!stack_tracer_enabled && !max_stack_size) | |
362 | print_disabled(m); | |
363 | ||
1b6cced6 SR |
364 | return 0; |
365 | } | |
e5a81b62 | 366 | |
522a110b LW |
367 | i = *(long *)v; |
368 | ||
1b6cced6 SR |
369 | if (i >= max_stack_trace.nr_entries || |
370 | stack_dump_trace[i] == ULONG_MAX) | |
e5a81b62 SR |
371 | return 0; |
372 | ||
1b6cced6 SR |
373 | if (i+1 == max_stack_trace.nr_entries || |
374 | stack_dump_trace[i+1] == ULONG_MAX) | |
375 | size = stack_dump_index[i]; | |
376 | else | |
377 | size = stack_dump_index[i] - stack_dump_index[i+1]; | |
378 | ||
379 | seq_printf(m, "%3ld) %8d %5d ", i, stack_dump_index[i], size); | |
380 | ||
381 | trace_lookup_stack(m, i); | |
e5a81b62 SR |
382 | |
383 | return 0; | |
384 | } | |
385 | ||
f38f1d2a | 386 | static const struct seq_operations stack_trace_seq_ops = { |
e5a81b62 SR |
387 | .start = t_start, |
388 | .next = t_next, | |
389 | .stop = t_stop, | |
390 | .show = t_show, | |
391 | }; | |
392 | ||
393 | static int stack_trace_open(struct inode *inode, struct file *file) | |
394 | { | |
d8cc1ab7 | 395 | return seq_open(file, &stack_trace_seq_ops); |
e5a81b62 SR |
396 | } |
397 | ||
f38f1d2a | 398 | static const struct file_operations stack_trace_fops = { |
e5a81b62 SR |
399 | .open = stack_trace_open, |
400 | .read = seq_read, | |
401 | .llseek = seq_lseek, | |
d8cc1ab7 | 402 | .release = seq_release, |
e5a81b62 SR |
403 | }; |
404 | ||
d2d45c7a SR |
405 | static int |
406 | stack_trace_filter_open(struct inode *inode, struct file *file) | |
407 | { | |
408 | return ftrace_regex_open(&trace_ops, FTRACE_ITER_FILTER, | |
409 | inode, file); | |
410 | } | |
411 | ||
412 | static const struct file_operations stack_trace_filter_fops = { | |
413 | .open = stack_trace_filter_open, | |
414 | .read = seq_read, | |
415 | .write = ftrace_filter_write, | |
098c879e | 416 | .llseek = tracing_lseek, |
d2d45c7a SR |
417 | .release = ftrace_regex_release, |
418 | }; | |
419 | ||
f38f1d2a SR |
420 | int |
421 | stack_trace_sysctl(struct ctl_table *table, int write, | |
8d65af78 | 422 | void __user *buffer, size_t *lenp, |
f38f1d2a SR |
423 | loff_t *ppos) |
424 | { | |
425 | int ret; | |
426 | ||
427 | mutex_lock(&stack_sysctl_mutex); | |
428 | ||
8d65af78 | 429 | ret = proc_dointvec(table, write, buffer, lenp, ppos); |
f38f1d2a SR |
430 | |
431 | if (ret || !write || | |
a32c7765 | 432 | (last_stack_tracer_enabled == !!stack_tracer_enabled)) |
f38f1d2a SR |
433 | goto out; |
434 | ||
a32c7765 | 435 | last_stack_tracer_enabled = !!stack_tracer_enabled; |
f38f1d2a SR |
436 | |
437 | if (stack_tracer_enabled) | |
438 | register_ftrace_function(&trace_ops); | |
439 | else | |
440 | unregister_ftrace_function(&trace_ops); | |
441 | ||
442 | out: | |
443 | mutex_unlock(&stack_sysctl_mutex); | |
444 | return ret; | |
445 | } | |
446 | ||
762e1207 SR |
447 | static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata; |
448 | ||
f38f1d2a SR |
449 | static __init int enable_stacktrace(char *str) |
450 | { | |
762e1207 SR |
451 | if (strncmp(str, "_filter=", 8) == 0) |
452 | strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE); | |
453 | ||
e05a43b7 SR |
454 | stack_tracer_enabled = 1; |
455 | last_stack_tracer_enabled = 1; | |
f38f1d2a SR |
456 | return 1; |
457 | } | |
458 | __setup("stacktrace", enable_stacktrace); | |
459 | ||
e5a81b62 SR |
460 | static __init int stack_trace_init(void) |
461 | { | |
462 | struct dentry *d_tracer; | |
e5a81b62 SR |
463 | |
464 | d_tracer = tracing_init_dentry(); | |
ed6f1c99 NK |
465 | if (!d_tracer) |
466 | return 0; | |
e5a81b62 | 467 | |
5452af66 FW |
468 | trace_create_file("stack_max_size", 0644, d_tracer, |
469 | &max_stack_size, &stack_max_size_fops); | |
e5a81b62 | 470 | |
5452af66 FW |
471 | trace_create_file("stack_trace", 0444, d_tracer, |
472 | NULL, &stack_trace_fops); | |
e5a81b62 | 473 | |
d2d45c7a SR |
474 | trace_create_file("stack_trace_filter", 0444, d_tracer, |
475 | NULL, &stack_trace_filter_fops); | |
476 | ||
762e1207 SR |
477 | if (stack_trace_filter_buf[0]) |
478 | ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1); | |
479 | ||
e05a43b7 | 480 | if (stack_tracer_enabled) |
f38f1d2a | 481 | register_ftrace_function(&trace_ops); |
e5a81b62 SR |
482 | |
483 | return 0; | |
484 | } | |
485 | ||
486 | device_initcall(stack_trace_init); |