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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
e5a81b62 SR |
2 | /* |
3 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
4 | * | |
5 | */ | |
68db0cf1 | 6 | #include <linux/sched/task_stack.h> |
e5a81b62 SR |
7 | #include <linux/stacktrace.h> |
8 | #include <linux/kallsyms.h> | |
9 | #include <linux/seq_file.h> | |
10 | #include <linux/spinlock.h> | |
11 | #include <linux/uaccess.h> | |
e5a81b62 SR |
12 | #include <linux/ftrace.h> |
13 | #include <linux/module.h> | |
f38f1d2a | 14 | #include <linux/sysctl.h> |
e5a81b62 | 15 | #include <linux/init.h> |
762e1207 SR |
16 | |
17 | #include <asm/setup.h> | |
18 | ||
e5a81b62 SR |
19 | #include "trace.h" |
20 | ||
3d9a8072 TG |
21 | #define STACK_TRACE_ENTRIES 500 |
22 | ||
23 | static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES]; | |
24 | static unsigned stack_trace_index[STACK_TRACE_ENTRIES]; | |
1b6cced6 | 25 | |
9f50c91b | 26 | static unsigned int stack_trace_nr_entries; |
3d9a8072 TG |
27 | static unsigned long stack_trace_max_size; |
28 | static arch_spinlock_t stack_trace_max_lock = | |
edc35bd7 | 29 | (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
e5a81b62 | 30 | |
8aaf1ee7 | 31 | DEFINE_PER_CPU(int, disable_stack_tracer); |
f38f1d2a SR |
32 | static DEFINE_MUTEX(stack_sysctl_mutex); |
33 | ||
34 | int stack_tracer_enabled; | |
e5a81b62 | 35 | |
3d9a8072 | 36 | static void print_max_stack(void) |
e3172181 MK |
37 | { |
38 | long i; | |
39 | int size; | |
40 | ||
41 | pr_emerg(" Depth Size Location (%d entries)\n" | |
42 | " ----- ---- --------\n", | |
9f50c91b | 43 | stack_trace_nr_entries); |
e3172181 | 44 | |
9f50c91b TG |
45 | for (i = 0; i < stack_trace_nr_entries; i++) { |
46 | if (i + 1 == stack_trace_nr_entries) | |
bb99d8cc | 47 | size = stack_trace_index[i]; |
e3172181 | 48 | else |
bb99d8cc | 49 | size = stack_trace_index[i] - stack_trace_index[i+1]; |
e3172181 | 50 | |
bb99d8cc | 51 | pr_emerg("%3ld) %8d %5d %pS\n", i, stack_trace_index[i], |
e3172181 MK |
52 | size, (void *)stack_dump_trace[i]); |
53 | } | |
54 | } | |
55 | ||
58fe7a87 SRV |
56 | /* |
57 | * The stack tracer looks for a maximum stack at each call from a function. It | |
58 | * registers a callback from ftrace, and in that callback it examines the stack | |
59 | * size. It determines the stack size from the variable passed in, which is the | |
60 | * address of a local variable in the stack_trace_call() callback function. | |
61 | * The stack size is calculated by the address of the local variable to the top | |
62 | * of the current stack. If that size is smaller than the currently saved max | |
63 | * stack size, nothing more is done. | |
64 | * | |
65 | * If the size of the stack is greater than the maximum recorded size, then the | |
66 | * following algorithm takes place. | |
67 | * | |
68 | * For architectures (like x86) that store the function's return address before | |
69 | * saving the function's local variables, the stack will look something like | |
70 | * this: | |
71 | * | |
72 | * [ top of stack ] | |
73 | * 0: sys call entry frame | |
74 | * 10: return addr to entry code | |
75 | * 11: start of sys_foo frame | |
76 | * 20: return addr to sys_foo | |
77 | * 21: start of kernel_func_bar frame | |
78 | * 30: return addr to kernel_func_bar | |
79 | * 31: [ do trace stack here ] | |
80 | * | |
81 | * The save_stack_trace() is called returning all the functions it finds in the | |
82 | * current stack. Which would be (from the bottom of the stack to the top): | |
83 | * | |
84 | * return addr to kernel_func_bar | |
85 | * return addr to sys_foo | |
86 | * return addr to entry code | |
87 | * | |
88 | * Now to figure out how much each of these functions' local variable size is, | |
89 | * a search of the stack is made to find these values. When a match is made, it | |
90 | * is added to the stack_dump_trace[] array. The offset into the stack is saved | |
91 | * in the stack_trace_index[] array. The above example would show: | |
92 | * | |
93 | * stack_dump_trace[] | stack_trace_index[] | |
94 | * ------------------ + ------------------- | |
95 | * return addr to kernel_func_bar | 30 | |
96 | * return addr to sys_foo | 20 | |
97 | * return addr to entry | 10 | |
98 | * | |
99 | * The print_max_stack() function above, uses these values to print the size of | |
100 | * each function's portion of the stack. | |
101 | * | |
102 | * for (i = 0; i < nr_entries; i++) { | |
103 | * size = i == nr_entries - 1 ? stack_trace_index[i] : | |
104 | * stack_trace_index[i] - stack_trace_index[i+1] | |
105 | * print "%d %d %d %s\n", i, stack_trace_index[i], size, stack_dump_trace[i]); | |
106 | * } | |
107 | * | |
108 | * The above shows | |
109 | * | |
110 | * depth size location | |
111 | * ----- ---- -------- | |
112 | * 0 30 10 kernel_func_bar | |
113 | * 1 20 10 sys_foo | |
114 | * 2 10 10 entry code | |
115 | * | |
116 | * Now for architectures that might save the return address after the functions | |
117 | * local variables (saving the link register before calling nested functions), | |
118 | * this will cause the stack to look a little different: | |
119 | * | |
120 | * [ top of stack ] | |
121 | * 0: sys call entry frame | |
122 | * 10: start of sys_foo_frame | |
123 | * 19: return addr to entry code << lr saved before calling kernel_func_bar | |
124 | * 20: start of kernel_func_bar frame | |
125 | * 29: return addr to sys_foo_frame << lr saved before calling next function | |
126 | * 30: [ do trace stack here ] | |
127 | * | |
128 | * Although the functions returned by save_stack_trace() may be the same, the | |
129 | * placement in the stack will be different. Using the same algorithm as above | |
130 | * would yield: | |
131 | * | |
132 | * stack_dump_trace[] | stack_trace_index[] | |
133 | * ------------------ + ------------------- | |
134 | * return addr to kernel_func_bar | 30 | |
135 | * return addr to sys_foo | 29 | |
136 | * return addr to entry | 19 | |
137 | * | |
138 | * Where the mapping is off by one: | |
139 | * | |
140 | * kernel_func_bar stack frame size is 29 - 19 not 30 - 29! | |
141 | * | |
142 | * To fix this, if the architecture sets ARCH_RET_ADDR_AFTER_LOCAL_VARS the | |
143 | * values in stack_trace_index[] are shifted by one to and the number of | |
144 | * stack trace entries is decremented by one. | |
145 | * | |
146 | * stack_dump_trace[] | stack_trace_index[] | |
147 | * ------------------ + ------------------- | |
148 | * return addr to kernel_func_bar | 29 | |
149 | * return addr to sys_foo | 19 | |
150 | * | |
151 | * Although the entry function is not displayed, the first function (sys_foo) | |
152 | * will still include the stack size of it. | |
153 | */ | |
3d9a8072 | 154 | static void check_stack(unsigned long ip, unsigned long *stack) |
e5a81b62 | 155 | { |
e3172181 | 156 | unsigned long this_size, flags; unsigned long *p, *top, *start; |
4df29712 | 157 | static int tracer_frame; |
6aa7de05 | 158 | int frame_size = READ_ONCE(tracer_frame); |
72ac426a | 159 | int i, x; |
e5a81b62 | 160 | |
87889501 | 161 | this_size = ((unsigned long)stack) & (THREAD_SIZE-1); |
e5a81b62 | 162 | this_size = THREAD_SIZE - this_size; |
4df29712 SRRH |
163 | /* Remove the frame of the tracer */ |
164 | this_size -= frame_size; | |
e5a81b62 | 165 | |
bb99d8cc | 166 | if (this_size <= stack_trace_max_size) |
e5a81b62 SR |
167 | return; |
168 | ||
81520a1b | 169 | /* we do not handle interrupt stacks yet */ |
87889501 | 170 | if (!object_is_on_stack(stack)) |
81520a1b SR |
171 | return; |
172 | ||
1904be1b SRRH |
173 | /* Can't do this from NMI context (can cause deadlocks) */ |
174 | if (in_nmi()) | |
175 | return; | |
176 | ||
a5e25883 | 177 | local_irq_save(flags); |
d332736d | 178 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 179 | |
4df29712 SRRH |
180 | /* In case another CPU set the tracer_frame on us */ |
181 | if (unlikely(!frame_size)) | |
182 | this_size -= tracer_frame; | |
183 | ||
e5a81b62 | 184 | /* a race could have already updated it */ |
bb99d8cc | 185 | if (this_size <= stack_trace_max_size) |
e5a81b62 SR |
186 | goto out; |
187 | ||
bb99d8cc | 188 | stack_trace_max_size = this_size; |
e5a81b62 | 189 | |
9f50c91b TG |
190 | stack_trace_nr_entries = stack_trace_save(stack_dump_trace, |
191 | ARRAY_SIZE(stack_dump_trace) - 1, | |
192 | 0); | |
e5a81b62 | 193 | |
72ac426a | 194 | /* Skip over the overhead of the stack tracer itself */ |
9f50c91b | 195 | for (i = 0; i < stack_trace_nr_entries; i++) { |
72ac426a SRRH |
196 | if (stack_dump_trace[i] == ip) |
197 | break; | |
198 | } | |
d4ecbfc4 | 199 | |
6ccd8371 SR |
200 | /* |
201 | * Some archs may not have the passed in ip in the dump. | |
202 | * If that happens, we need to show everything. | |
203 | */ | |
9f50c91b | 204 | if (i == stack_trace_nr_entries) |
6ccd8371 SR |
205 | i = 0; |
206 | ||
1b6cced6 SR |
207 | /* |
208 | * Now find where in the stack these are. | |
209 | */ | |
72ac426a | 210 | x = 0; |
87889501 | 211 | start = stack; |
1b6cced6 SR |
212 | top = (unsigned long *) |
213 | (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE); | |
214 | ||
215 | /* | |
216 | * Loop through all the entries. One of the entries may | |
217 | * for some reason be missed on the stack, so we may | |
218 | * have to account for them. If they are all there, this | |
219 | * loop will only happen once. This code only takes place | |
220 | * on a new max, so it is far from a fast path. | |
221 | */ | |
9f50c91b | 222 | while (i < stack_trace_nr_entries) { |
0a37119d | 223 | int found = 0; |
1b6cced6 | 224 | |
bb99d8cc | 225 | stack_trace_index[x] = this_size; |
1b6cced6 SR |
226 | p = start; |
227 | ||
9f50c91b | 228 | for (; p < top && i < stack_trace_nr_entries; p++) { |
6e22c836 YS |
229 | /* |
230 | * The READ_ONCE_NOCHECK is used to let KASAN know that | |
231 | * this is not a stack-out-of-bounds error. | |
232 | */ | |
233 | if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) { | |
72ac426a | 234 | stack_dump_trace[x] = stack_dump_trace[i++]; |
bb99d8cc | 235 | this_size = stack_trace_index[x++] = |
1b6cced6 | 236 | (top - p) * sizeof(unsigned long); |
0a37119d | 237 | found = 1; |
1b6cced6 SR |
238 | /* Start the search from here */ |
239 | start = p + 1; | |
4df29712 SRRH |
240 | /* |
241 | * We do not want to show the overhead | |
242 | * of the stack tracer stack in the | |
243 | * max stack. If we haven't figured | |
244 | * out what that is, then figure it out | |
245 | * now. | |
246 | */ | |
72ac426a | 247 | if (unlikely(!tracer_frame)) { |
4df29712 SRRH |
248 | tracer_frame = (p - stack) * |
249 | sizeof(unsigned long); | |
bb99d8cc | 250 | stack_trace_max_size -= tracer_frame; |
4df29712 | 251 | } |
1b6cced6 SR |
252 | } |
253 | } | |
254 | ||
0a37119d SR |
255 | if (!found) |
256 | i++; | |
1b6cced6 SR |
257 | } |
258 | ||
f7edb451 SRV |
259 | #ifdef ARCH_FTRACE_SHIFT_STACK_TRACER |
260 | /* | |
261 | * Some archs will store the link register before calling | |
262 | * nested functions. This means the saved return address | |
263 | * comes after the local storage, and we need to shift | |
264 | * for that. | |
265 | */ | |
266 | if (x > 1) { | |
267 | memmove(&stack_trace_index[0], &stack_trace_index[1], | |
268 | sizeof(stack_trace_index[0]) * (x - 1)); | |
269 | x--; | |
270 | } | |
271 | #endif | |
272 | ||
9f50c91b | 273 | stack_trace_nr_entries = x; |
72ac426a | 274 | |
a70857e4 | 275 | if (task_stack_end_corrupted(current)) { |
3d9a8072 | 276 | print_max_stack(); |
e3172181 MK |
277 | BUG(); |
278 | } | |
279 | ||
e5a81b62 | 280 | out: |
d332736d | 281 | arch_spin_unlock(&stack_trace_max_lock); |
a5e25883 | 282 | local_irq_restore(flags); |
e5a81b62 SR |
283 | } |
284 | ||
285 | static void | |
a1e2e31d SR |
286 | stack_trace_call(unsigned long ip, unsigned long parent_ip, |
287 | struct ftrace_ops *op, struct pt_regs *pt_regs) | |
e5a81b62 | 288 | { |
87889501 | 289 | unsigned long stack; |
e5a81b62 | 290 | |
5168ae50 | 291 | preempt_disable_notrace(); |
e5a81b62 | 292 | |
e5a81b62 | 293 | /* no atomic needed, we only modify this variable by this cpu */ |
8aaf1ee7 SRV |
294 | __this_cpu_inc(disable_stack_tracer); |
295 | if (__this_cpu_read(disable_stack_tracer) != 1) | |
e5a81b62 SR |
296 | goto out; |
297 | ||
b00d607b SRV |
298 | /* If rcu is not watching, then save stack trace can fail */ |
299 | if (!rcu_is_watching()) | |
300 | goto out; | |
301 | ||
72ac426a | 302 | ip += MCOUNT_INSN_SIZE; |
4df29712 SRRH |
303 | |
304 | check_stack(ip, &stack); | |
e5a81b62 SR |
305 | |
306 | out: | |
8aaf1ee7 | 307 | __this_cpu_dec(disable_stack_tracer); |
e5a81b62 | 308 | /* prevent recursion in schedule */ |
5168ae50 | 309 | preempt_enable_notrace(); |
e5a81b62 SR |
310 | } |
311 | ||
312 | static struct ftrace_ops trace_ops __read_mostly = | |
313 | { | |
314 | .func = stack_trace_call, | |
4740974a | 315 | .flags = FTRACE_OPS_FL_RECURSION_SAFE, |
e5a81b62 SR |
316 | }; |
317 | ||
318 | static ssize_t | |
319 | stack_max_size_read(struct file *filp, char __user *ubuf, | |
320 | size_t count, loff_t *ppos) | |
321 | { | |
322 | unsigned long *ptr = filp->private_data; | |
323 | char buf[64]; | |
324 | int r; | |
325 | ||
326 | r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); | |
327 | if (r > sizeof(buf)) | |
328 | r = sizeof(buf); | |
329 | return simple_read_from_buffer(ubuf, count, ppos, buf, r); | |
330 | } | |
331 | ||
332 | static ssize_t | |
333 | stack_max_size_write(struct file *filp, const char __user *ubuf, | |
334 | size_t count, loff_t *ppos) | |
335 | { | |
336 | long *ptr = filp->private_data; | |
337 | unsigned long val, flags; | |
e5a81b62 SR |
338 | int ret; |
339 | ||
22fe9b54 PH |
340 | ret = kstrtoul_from_user(ubuf, count, 10, &val); |
341 | if (ret) | |
e5a81b62 SR |
342 | return ret; |
343 | ||
a5e25883 | 344 | local_irq_save(flags); |
4f48f8b7 LJ |
345 | |
346 | /* | |
347 | * In case we trace inside arch_spin_lock() or after (NMI), | |
348 | * we will cause circular lock, so we also need to increase | |
8aaf1ee7 | 349 | * the percpu disable_stack_tracer here. |
4f48f8b7 | 350 | */ |
8aaf1ee7 | 351 | __this_cpu_inc(disable_stack_tracer); |
4f48f8b7 | 352 | |
d332736d | 353 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 354 | *ptr = val; |
d332736d | 355 | arch_spin_unlock(&stack_trace_max_lock); |
4f48f8b7 | 356 | |
8aaf1ee7 | 357 | __this_cpu_dec(disable_stack_tracer); |
a5e25883 | 358 | local_irq_restore(flags); |
e5a81b62 SR |
359 | |
360 | return count; | |
361 | } | |
362 | ||
f38f1d2a | 363 | static const struct file_operations stack_max_size_fops = { |
e5a81b62 SR |
364 | .open = tracing_open_generic, |
365 | .read = stack_max_size_read, | |
366 | .write = stack_max_size_write, | |
6038f373 | 367 | .llseek = default_llseek, |
e5a81b62 SR |
368 | }; |
369 | ||
370 | static void * | |
2fc5f0cf | 371 | __next(struct seq_file *m, loff_t *pos) |
e5a81b62 | 372 | { |
2fc5f0cf | 373 | long n = *pos - 1; |
e5a81b62 | 374 | |
9f50c91b | 375 | if (n >= stack_trace_nr_entries) |
e5a81b62 SR |
376 | return NULL; |
377 | ||
2fc5f0cf | 378 | m->private = (void *)n; |
1b6cced6 | 379 | return &m->private; |
e5a81b62 SR |
380 | } |
381 | ||
2fc5f0cf LZ |
382 | static void * |
383 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
e5a81b62 | 384 | { |
2fc5f0cf LZ |
385 | (*pos)++; |
386 | return __next(m, pos); | |
387 | } | |
e5a81b62 | 388 | |
2fc5f0cf LZ |
389 | static void *t_start(struct seq_file *m, loff_t *pos) |
390 | { | |
e5a81b62 | 391 | local_irq_disable(); |
4f48f8b7 | 392 | |
8aaf1ee7 | 393 | __this_cpu_inc(disable_stack_tracer); |
4f48f8b7 | 394 | |
d332736d | 395 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 396 | |
522a110b LW |
397 | if (*pos == 0) |
398 | return SEQ_START_TOKEN; | |
399 | ||
2fc5f0cf | 400 | return __next(m, pos); |
e5a81b62 SR |
401 | } |
402 | ||
403 | static void t_stop(struct seq_file *m, void *p) | |
404 | { | |
d332736d | 405 | arch_spin_unlock(&stack_trace_max_lock); |
4f48f8b7 | 406 | |
8aaf1ee7 | 407 | __this_cpu_dec(disable_stack_tracer); |
4f48f8b7 | 408 | |
e5a81b62 SR |
409 | local_irq_enable(); |
410 | } | |
411 | ||
962e3707 | 412 | static void trace_lookup_stack(struct seq_file *m, long i) |
e5a81b62 | 413 | { |
1b6cced6 | 414 | unsigned long addr = stack_dump_trace[i]; |
e5a81b62 | 415 | |
962e3707 | 416 | seq_printf(m, "%pS\n", (void *)addr); |
e5a81b62 SR |
417 | } |
418 | ||
e447e1df SR |
419 | static void print_disabled(struct seq_file *m) |
420 | { | |
421 | seq_puts(m, "#\n" | |
422 | "# Stack tracer disabled\n" | |
423 | "#\n" | |
424 | "# To enable the stack tracer, either add 'stacktrace' to the\n" | |
425 | "# kernel command line\n" | |
426 | "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n" | |
427 | "#\n"); | |
428 | } | |
429 | ||
e5a81b62 SR |
430 | static int t_show(struct seq_file *m, void *v) |
431 | { | |
522a110b | 432 | long i; |
1b6cced6 SR |
433 | int size; |
434 | ||
522a110b | 435 | if (v == SEQ_START_TOKEN) { |
eb1871f3 | 436 | seq_printf(m, " Depth Size Location" |
1b6cced6 | 437 | " (%d entries)\n" |
eb1871f3 | 438 | " ----- ---- --------\n", |
9f50c91b | 439 | stack_trace_nr_entries); |
e447e1df | 440 | |
bb99d8cc | 441 | if (!stack_tracer_enabled && !stack_trace_max_size) |
e447e1df SR |
442 | print_disabled(m); |
443 | ||
1b6cced6 SR |
444 | return 0; |
445 | } | |
e5a81b62 | 446 | |
522a110b LW |
447 | i = *(long *)v; |
448 | ||
9f50c91b | 449 | if (i >= stack_trace_nr_entries) |
e5a81b62 SR |
450 | return 0; |
451 | ||
9f50c91b | 452 | if (i + 1 == stack_trace_nr_entries) |
bb99d8cc | 453 | size = stack_trace_index[i]; |
1b6cced6 | 454 | else |
bb99d8cc | 455 | size = stack_trace_index[i] - stack_trace_index[i+1]; |
1b6cced6 | 456 | |
bb99d8cc | 457 | seq_printf(m, "%3ld) %8d %5d ", i, stack_trace_index[i], size); |
1b6cced6 SR |
458 | |
459 | trace_lookup_stack(m, i); | |
e5a81b62 SR |
460 | |
461 | return 0; | |
462 | } | |
463 | ||
f38f1d2a | 464 | static const struct seq_operations stack_trace_seq_ops = { |
e5a81b62 SR |
465 | .start = t_start, |
466 | .next = t_next, | |
467 | .stop = t_stop, | |
468 | .show = t_show, | |
469 | }; | |
470 | ||
471 | static int stack_trace_open(struct inode *inode, struct file *file) | |
472 | { | |
d8cc1ab7 | 473 | return seq_open(file, &stack_trace_seq_ops); |
e5a81b62 SR |
474 | } |
475 | ||
f38f1d2a | 476 | static const struct file_operations stack_trace_fops = { |
e5a81b62 SR |
477 | .open = stack_trace_open, |
478 | .read = seq_read, | |
479 | .llseek = seq_lseek, | |
d8cc1ab7 | 480 | .release = seq_release, |
e5a81b62 SR |
481 | }; |
482 | ||
bbd1d27d SRV |
483 | #ifdef CONFIG_DYNAMIC_FTRACE |
484 | ||
d2d45c7a SR |
485 | static int |
486 | stack_trace_filter_open(struct inode *inode, struct file *file) | |
487 | { | |
0f179765 SRV |
488 | struct ftrace_ops *ops = inode->i_private; |
489 | ||
490 | return ftrace_regex_open(ops, FTRACE_ITER_FILTER, | |
d2d45c7a SR |
491 | inode, file); |
492 | } | |
493 | ||
494 | static const struct file_operations stack_trace_filter_fops = { | |
495 | .open = stack_trace_filter_open, | |
496 | .read = seq_read, | |
497 | .write = ftrace_filter_write, | |
098c879e | 498 | .llseek = tracing_lseek, |
d2d45c7a SR |
499 | .release = ftrace_regex_release, |
500 | }; | |
501 | ||
bbd1d27d SRV |
502 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
503 | ||
f38f1d2a SR |
504 | int |
505 | stack_trace_sysctl(struct ctl_table *table, int write, | |
8d65af78 | 506 | void __user *buffer, size_t *lenp, |
f38f1d2a SR |
507 | loff_t *ppos) |
508 | { | |
3d9a8072 | 509 | int was_enabled; |
f38f1d2a SR |
510 | int ret; |
511 | ||
512 | mutex_lock(&stack_sysctl_mutex); | |
3d9a8072 | 513 | was_enabled = !!stack_tracer_enabled; |
f38f1d2a | 514 | |
8d65af78 | 515 | ret = proc_dointvec(table, write, buffer, lenp, ppos); |
f38f1d2a | 516 | |
3d9a8072 | 517 | if (ret || !write || (was_enabled == !!stack_tracer_enabled)) |
f38f1d2a SR |
518 | goto out; |
519 | ||
f38f1d2a SR |
520 | if (stack_tracer_enabled) |
521 | register_ftrace_function(&trace_ops); | |
522 | else | |
523 | unregister_ftrace_function(&trace_ops); | |
f38f1d2a SR |
524 | out: |
525 | mutex_unlock(&stack_sysctl_mutex); | |
526 | return ret; | |
527 | } | |
528 | ||
762e1207 SR |
529 | static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata; |
530 | ||
f38f1d2a SR |
531 | static __init int enable_stacktrace(char *str) |
532 | { | |
3d739c1f SRV |
533 | int len; |
534 | ||
535 | if ((len = str_has_prefix(str, "_filter="))) | |
536 | strncpy(stack_trace_filter_buf, str + len, COMMAND_LINE_SIZE); | |
762e1207 | 537 | |
e05a43b7 | 538 | stack_tracer_enabled = 1; |
f38f1d2a SR |
539 | return 1; |
540 | } | |
541 | __setup("stacktrace", enable_stacktrace); | |
542 | ||
e5a81b62 SR |
543 | static __init int stack_trace_init(void) |
544 | { | |
545 | struct dentry *d_tracer; | |
e5a81b62 SR |
546 | |
547 | d_tracer = tracing_init_dentry(); | |
14a5ae40 | 548 | if (IS_ERR(d_tracer)) |
ed6f1c99 | 549 | return 0; |
e5a81b62 | 550 | |
5452af66 | 551 | trace_create_file("stack_max_size", 0644, d_tracer, |
bb99d8cc | 552 | &stack_trace_max_size, &stack_max_size_fops); |
e5a81b62 | 553 | |
5452af66 FW |
554 | trace_create_file("stack_trace", 0444, d_tracer, |
555 | NULL, &stack_trace_fops); | |
e5a81b62 | 556 | |
bbd1d27d | 557 | #ifdef CONFIG_DYNAMIC_FTRACE |
0c5a9acc | 558 | trace_create_file("stack_trace_filter", 0644, d_tracer, |
0f179765 | 559 | &trace_ops, &stack_trace_filter_fops); |
bbd1d27d | 560 | #endif |
d2d45c7a | 561 | |
762e1207 SR |
562 | if (stack_trace_filter_buf[0]) |
563 | ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1); | |
564 | ||
e05a43b7 | 565 | if (stack_tracer_enabled) |
f38f1d2a | 566 | register_ftrace_function(&trace_ops); |
e5a81b62 SR |
567 | |
568 | return 0; | |
569 | } | |
570 | ||
571 | device_initcall(stack_trace_init); |