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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 | 7 | #include <linux/stacktrace.h> |
17911ff3 | 8 | #include <linux/security.h> |
e5a81b62 SR |
9 | #include <linux/kallsyms.h> |
10 | #include <linux/seq_file.h> | |
11 | #include <linux/spinlock.h> | |
12 | #include <linux/uaccess.h> | |
e5a81b62 SR |
13 | #include <linux/ftrace.h> |
14 | #include <linux/module.h> | |
f38f1d2a | 15 | #include <linux/sysctl.h> |
e5a81b62 | 16 | #include <linux/init.h> |
762e1207 SR |
17 | |
18 | #include <asm/setup.h> | |
19 | ||
e5a81b62 SR |
20 | #include "trace.h" |
21 | ||
3d9a8072 TG |
22 | #define STACK_TRACE_ENTRIES 500 |
23 | ||
24 | static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES]; | |
25 | static unsigned stack_trace_index[STACK_TRACE_ENTRIES]; | |
1b6cced6 | 26 | |
9f50c91b | 27 | static unsigned int stack_trace_nr_entries; |
3d9a8072 TG |
28 | static unsigned long stack_trace_max_size; |
29 | static arch_spinlock_t stack_trace_max_lock = | |
edc35bd7 | 30 | (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; |
e5a81b62 | 31 | |
8aaf1ee7 | 32 | DEFINE_PER_CPU(int, disable_stack_tracer); |
f38f1d2a SR |
33 | static DEFINE_MUTEX(stack_sysctl_mutex); |
34 | ||
35 | int stack_tracer_enabled; | |
e5a81b62 | 36 | |
3d9a8072 | 37 | static void print_max_stack(void) |
e3172181 MK |
38 | { |
39 | long i; | |
40 | int size; | |
41 | ||
42 | pr_emerg(" Depth Size Location (%d entries)\n" | |
43 | " ----- ---- --------\n", | |
9f50c91b | 44 | stack_trace_nr_entries); |
e3172181 | 45 | |
9f50c91b TG |
46 | for (i = 0; i < stack_trace_nr_entries; i++) { |
47 | if (i + 1 == stack_trace_nr_entries) | |
bb99d8cc | 48 | size = stack_trace_index[i]; |
e3172181 | 49 | else |
bb99d8cc | 50 | size = stack_trace_index[i] - stack_trace_index[i+1]; |
e3172181 | 51 | |
bb99d8cc | 52 | pr_emerg("%3ld) %8d %5d %pS\n", i, stack_trace_index[i], |
e3172181 MK |
53 | size, (void *)stack_dump_trace[i]); |
54 | } | |
55 | } | |
56 | ||
58fe7a87 SRV |
57 | /* |
58 | * The stack tracer looks for a maximum stack at each call from a function. It | |
59 | * registers a callback from ftrace, and in that callback it examines the stack | |
60 | * size. It determines the stack size from the variable passed in, which is the | |
61 | * address of a local variable in the stack_trace_call() callback function. | |
62 | * The stack size is calculated by the address of the local variable to the top | |
63 | * of the current stack. If that size is smaller than the currently saved max | |
64 | * stack size, nothing more is done. | |
65 | * | |
66 | * If the size of the stack is greater than the maximum recorded size, then the | |
67 | * following algorithm takes place. | |
68 | * | |
69 | * For architectures (like x86) that store the function's return address before | |
70 | * saving the function's local variables, the stack will look something like | |
71 | * this: | |
72 | * | |
73 | * [ top of stack ] | |
74 | * 0: sys call entry frame | |
75 | * 10: return addr to entry code | |
76 | * 11: start of sys_foo frame | |
77 | * 20: return addr to sys_foo | |
78 | * 21: start of kernel_func_bar frame | |
79 | * 30: return addr to kernel_func_bar | |
80 | * 31: [ do trace stack here ] | |
81 | * | |
82 | * The save_stack_trace() is called returning all the functions it finds in the | |
83 | * current stack. Which would be (from the bottom of the stack to the top): | |
84 | * | |
85 | * return addr to kernel_func_bar | |
86 | * return addr to sys_foo | |
87 | * return addr to entry code | |
88 | * | |
89 | * Now to figure out how much each of these functions' local variable size is, | |
90 | * a search of the stack is made to find these values. When a match is made, it | |
91 | * is added to the stack_dump_trace[] array. The offset into the stack is saved | |
92 | * in the stack_trace_index[] array. The above example would show: | |
93 | * | |
94 | * stack_dump_trace[] | stack_trace_index[] | |
95 | * ------------------ + ------------------- | |
96 | * return addr to kernel_func_bar | 30 | |
97 | * return addr to sys_foo | 20 | |
98 | * return addr to entry | 10 | |
99 | * | |
100 | * The print_max_stack() function above, uses these values to print the size of | |
101 | * each function's portion of the stack. | |
102 | * | |
103 | * for (i = 0; i < nr_entries; i++) { | |
104 | * size = i == nr_entries - 1 ? stack_trace_index[i] : | |
105 | * stack_trace_index[i] - stack_trace_index[i+1] | |
106 | * print "%d %d %d %s\n", i, stack_trace_index[i], size, stack_dump_trace[i]); | |
107 | * } | |
108 | * | |
109 | * The above shows | |
110 | * | |
111 | * depth size location | |
112 | * ----- ---- -------- | |
113 | * 0 30 10 kernel_func_bar | |
114 | * 1 20 10 sys_foo | |
115 | * 2 10 10 entry code | |
116 | * | |
117 | * Now for architectures that might save the return address after the functions | |
118 | * local variables (saving the link register before calling nested functions), | |
119 | * this will cause the stack to look a little different: | |
120 | * | |
121 | * [ top of stack ] | |
122 | * 0: sys call entry frame | |
123 | * 10: start of sys_foo_frame | |
124 | * 19: return addr to entry code << lr saved before calling kernel_func_bar | |
125 | * 20: start of kernel_func_bar frame | |
126 | * 29: return addr to sys_foo_frame << lr saved before calling next function | |
127 | * 30: [ do trace stack here ] | |
128 | * | |
129 | * Although the functions returned by save_stack_trace() may be the same, the | |
130 | * placement in the stack will be different. Using the same algorithm as above | |
131 | * would yield: | |
132 | * | |
133 | * stack_dump_trace[] | stack_trace_index[] | |
134 | * ------------------ + ------------------- | |
135 | * return addr to kernel_func_bar | 30 | |
136 | * return addr to sys_foo | 29 | |
137 | * return addr to entry | 19 | |
138 | * | |
139 | * Where the mapping is off by one: | |
140 | * | |
141 | * kernel_func_bar stack frame size is 29 - 19 not 30 - 29! | |
142 | * | |
143 | * To fix this, if the architecture sets ARCH_RET_ADDR_AFTER_LOCAL_VARS the | |
144 | * values in stack_trace_index[] are shifted by one to and the number of | |
145 | * stack trace entries is decremented by one. | |
146 | * | |
147 | * stack_dump_trace[] | stack_trace_index[] | |
148 | * ------------------ + ------------------- | |
149 | * return addr to kernel_func_bar | 29 | |
150 | * return addr to sys_foo | 19 | |
151 | * | |
152 | * Although the entry function is not displayed, the first function (sys_foo) | |
153 | * will still include the stack size of it. | |
154 | */ | |
3d9a8072 | 155 | static void check_stack(unsigned long ip, unsigned long *stack) |
e5a81b62 | 156 | { |
e3172181 | 157 | unsigned long this_size, flags; unsigned long *p, *top, *start; |
4df29712 | 158 | static int tracer_frame; |
6aa7de05 | 159 | int frame_size = READ_ONCE(tracer_frame); |
72ac426a | 160 | int i, x; |
e5a81b62 | 161 | |
87889501 | 162 | this_size = ((unsigned long)stack) & (THREAD_SIZE-1); |
e5a81b62 | 163 | this_size = THREAD_SIZE - this_size; |
4df29712 SRRH |
164 | /* Remove the frame of the tracer */ |
165 | this_size -= frame_size; | |
e5a81b62 | 166 | |
bb99d8cc | 167 | if (this_size <= stack_trace_max_size) |
e5a81b62 SR |
168 | return; |
169 | ||
81520a1b | 170 | /* we do not handle interrupt stacks yet */ |
87889501 | 171 | if (!object_is_on_stack(stack)) |
81520a1b SR |
172 | return; |
173 | ||
1904be1b SRRH |
174 | /* Can't do this from NMI context (can cause deadlocks) */ |
175 | if (in_nmi()) | |
176 | return; | |
177 | ||
a5e25883 | 178 | local_irq_save(flags); |
d332736d | 179 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 180 | |
4df29712 SRRH |
181 | /* In case another CPU set the tracer_frame on us */ |
182 | if (unlikely(!frame_size)) | |
183 | this_size -= tracer_frame; | |
184 | ||
e5a81b62 | 185 | /* a race could have already updated it */ |
bb99d8cc | 186 | if (this_size <= stack_trace_max_size) |
e5a81b62 SR |
187 | goto out; |
188 | ||
bb99d8cc | 189 | stack_trace_max_size = this_size; |
e5a81b62 | 190 | |
9f50c91b TG |
191 | stack_trace_nr_entries = stack_trace_save(stack_dump_trace, |
192 | ARRAY_SIZE(stack_dump_trace) - 1, | |
193 | 0); | |
e5a81b62 | 194 | |
72ac426a | 195 | /* Skip over the overhead of the stack tracer itself */ |
9f50c91b | 196 | for (i = 0; i < stack_trace_nr_entries; i++) { |
72ac426a SRRH |
197 | if (stack_dump_trace[i] == ip) |
198 | break; | |
199 | } | |
d4ecbfc4 | 200 | |
6ccd8371 SR |
201 | /* |
202 | * Some archs may not have the passed in ip in the dump. | |
203 | * If that happens, we need to show everything. | |
204 | */ | |
9f50c91b | 205 | if (i == stack_trace_nr_entries) |
6ccd8371 SR |
206 | i = 0; |
207 | ||
1b6cced6 SR |
208 | /* |
209 | * Now find where in the stack these are. | |
210 | */ | |
72ac426a | 211 | x = 0; |
87889501 | 212 | start = stack; |
1b6cced6 SR |
213 | top = (unsigned long *) |
214 | (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE); | |
215 | ||
216 | /* | |
217 | * Loop through all the entries. One of the entries may | |
218 | * for some reason be missed on the stack, so we may | |
219 | * have to account for them. If they are all there, this | |
220 | * loop will only happen once. This code only takes place | |
221 | * on a new max, so it is far from a fast path. | |
222 | */ | |
9f50c91b | 223 | while (i < stack_trace_nr_entries) { |
0a37119d | 224 | int found = 0; |
1b6cced6 | 225 | |
bb99d8cc | 226 | stack_trace_index[x] = this_size; |
1b6cced6 SR |
227 | p = start; |
228 | ||
9f50c91b | 229 | for (; p < top && i < stack_trace_nr_entries; p++) { |
6e22c836 YS |
230 | /* |
231 | * The READ_ONCE_NOCHECK is used to let KASAN know that | |
232 | * this is not a stack-out-of-bounds error. | |
233 | */ | |
234 | if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) { | |
72ac426a | 235 | stack_dump_trace[x] = stack_dump_trace[i++]; |
bb99d8cc | 236 | this_size = stack_trace_index[x++] = |
1b6cced6 | 237 | (top - p) * sizeof(unsigned long); |
0a37119d | 238 | found = 1; |
1b6cced6 SR |
239 | /* Start the search from here */ |
240 | start = p + 1; | |
4df29712 SRRH |
241 | /* |
242 | * We do not want to show the overhead | |
243 | * of the stack tracer stack in the | |
244 | * max stack. If we haven't figured | |
245 | * out what that is, then figure it out | |
246 | * now. | |
247 | */ | |
72ac426a | 248 | if (unlikely(!tracer_frame)) { |
4df29712 SRRH |
249 | tracer_frame = (p - stack) * |
250 | sizeof(unsigned long); | |
bb99d8cc | 251 | stack_trace_max_size -= tracer_frame; |
4df29712 | 252 | } |
1b6cced6 SR |
253 | } |
254 | } | |
255 | ||
0a37119d SR |
256 | if (!found) |
257 | i++; | |
1b6cced6 SR |
258 | } |
259 | ||
f7edb451 SRV |
260 | #ifdef ARCH_FTRACE_SHIFT_STACK_TRACER |
261 | /* | |
262 | * Some archs will store the link register before calling | |
263 | * nested functions. This means the saved return address | |
264 | * comes after the local storage, and we need to shift | |
265 | * for that. | |
266 | */ | |
267 | if (x > 1) { | |
268 | memmove(&stack_trace_index[0], &stack_trace_index[1], | |
269 | sizeof(stack_trace_index[0]) * (x - 1)); | |
270 | x--; | |
271 | } | |
272 | #endif | |
273 | ||
9f50c91b | 274 | stack_trace_nr_entries = x; |
72ac426a | 275 | |
a70857e4 | 276 | if (task_stack_end_corrupted(current)) { |
3d9a8072 | 277 | print_max_stack(); |
e3172181 MK |
278 | BUG(); |
279 | } | |
280 | ||
e5a81b62 | 281 | out: |
d332736d | 282 | arch_spin_unlock(&stack_trace_max_lock); |
a5e25883 | 283 | local_irq_restore(flags); |
e5a81b62 SR |
284 | } |
285 | ||
286 | static void | |
a1e2e31d SR |
287 | stack_trace_call(unsigned long ip, unsigned long parent_ip, |
288 | struct ftrace_ops *op, struct pt_regs *pt_regs) | |
e5a81b62 | 289 | { |
87889501 | 290 | unsigned long stack; |
e5a81b62 | 291 | |
5168ae50 | 292 | preempt_disable_notrace(); |
e5a81b62 | 293 | |
e5a81b62 | 294 | /* no atomic needed, we only modify this variable by this cpu */ |
8aaf1ee7 SRV |
295 | __this_cpu_inc(disable_stack_tracer); |
296 | if (__this_cpu_read(disable_stack_tracer) != 1) | |
e5a81b62 SR |
297 | goto out; |
298 | ||
b00d607b SRV |
299 | /* If rcu is not watching, then save stack trace can fail */ |
300 | if (!rcu_is_watching()) | |
301 | goto out; | |
302 | ||
72ac426a | 303 | ip += MCOUNT_INSN_SIZE; |
4df29712 SRRH |
304 | |
305 | check_stack(ip, &stack); | |
e5a81b62 SR |
306 | |
307 | out: | |
8aaf1ee7 | 308 | __this_cpu_dec(disable_stack_tracer); |
e5a81b62 | 309 | /* prevent recursion in schedule */ |
5168ae50 | 310 | preempt_enable_notrace(); |
e5a81b62 SR |
311 | } |
312 | ||
313 | static struct ftrace_ops trace_ops __read_mostly = | |
314 | { | |
315 | .func = stack_trace_call, | |
4740974a | 316 | .flags = FTRACE_OPS_FL_RECURSION_SAFE, |
e5a81b62 SR |
317 | }; |
318 | ||
319 | static ssize_t | |
320 | stack_max_size_read(struct file *filp, char __user *ubuf, | |
321 | size_t count, loff_t *ppos) | |
322 | { | |
323 | unsigned long *ptr = filp->private_data; | |
324 | char buf[64]; | |
325 | int r; | |
326 | ||
327 | r = snprintf(buf, sizeof(buf), "%ld\n", *ptr); | |
328 | if (r > sizeof(buf)) | |
329 | r = sizeof(buf); | |
330 | return simple_read_from_buffer(ubuf, count, ppos, buf, r); | |
331 | } | |
332 | ||
333 | static ssize_t | |
334 | stack_max_size_write(struct file *filp, const char __user *ubuf, | |
335 | size_t count, loff_t *ppos) | |
336 | { | |
337 | long *ptr = filp->private_data; | |
338 | unsigned long val, flags; | |
e5a81b62 SR |
339 | int ret; |
340 | ||
22fe9b54 PH |
341 | ret = kstrtoul_from_user(ubuf, count, 10, &val); |
342 | if (ret) | |
e5a81b62 SR |
343 | return ret; |
344 | ||
a5e25883 | 345 | local_irq_save(flags); |
4f48f8b7 LJ |
346 | |
347 | /* | |
348 | * In case we trace inside arch_spin_lock() or after (NMI), | |
349 | * we will cause circular lock, so we also need to increase | |
8aaf1ee7 | 350 | * the percpu disable_stack_tracer here. |
4f48f8b7 | 351 | */ |
8aaf1ee7 | 352 | __this_cpu_inc(disable_stack_tracer); |
4f48f8b7 | 353 | |
d332736d | 354 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 355 | *ptr = val; |
d332736d | 356 | arch_spin_unlock(&stack_trace_max_lock); |
4f48f8b7 | 357 | |
8aaf1ee7 | 358 | __this_cpu_dec(disable_stack_tracer); |
a5e25883 | 359 | local_irq_restore(flags); |
e5a81b62 SR |
360 | |
361 | return count; | |
362 | } | |
363 | ||
f38f1d2a | 364 | static const struct file_operations stack_max_size_fops = { |
e5a81b62 SR |
365 | .open = tracing_open_generic, |
366 | .read = stack_max_size_read, | |
367 | .write = stack_max_size_write, | |
6038f373 | 368 | .llseek = default_llseek, |
e5a81b62 SR |
369 | }; |
370 | ||
371 | static void * | |
2fc5f0cf | 372 | __next(struct seq_file *m, loff_t *pos) |
e5a81b62 | 373 | { |
2fc5f0cf | 374 | long n = *pos - 1; |
e5a81b62 | 375 | |
9f50c91b | 376 | if (n >= stack_trace_nr_entries) |
e5a81b62 SR |
377 | return NULL; |
378 | ||
2fc5f0cf | 379 | m->private = (void *)n; |
1b6cced6 | 380 | return &m->private; |
e5a81b62 SR |
381 | } |
382 | ||
2fc5f0cf LZ |
383 | static void * |
384 | t_next(struct seq_file *m, void *v, loff_t *pos) | |
e5a81b62 | 385 | { |
2fc5f0cf LZ |
386 | (*pos)++; |
387 | return __next(m, pos); | |
388 | } | |
e5a81b62 | 389 | |
2fc5f0cf LZ |
390 | static void *t_start(struct seq_file *m, loff_t *pos) |
391 | { | |
e5a81b62 | 392 | local_irq_disable(); |
4f48f8b7 | 393 | |
8aaf1ee7 | 394 | __this_cpu_inc(disable_stack_tracer); |
4f48f8b7 | 395 | |
d332736d | 396 | arch_spin_lock(&stack_trace_max_lock); |
e5a81b62 | 397 | |
522a110b LW |
398 | if (*pos == 0) |
399 | return SEQ_START_TOKEN; | |
400 | ||
2fc5f0cf | 401 | return __next(m, pos); |
e5a81b62 SR |
402 | } |
403 | ||
404 | static void t_stop(struct seq_file *m, void *p) | |
405 | { | |
d332736d | 406 | arch_spin_unlock(&stack_trace_max_lock); |
4f48f8b7 | 407 | |
8aaf1ee7 | 408 | __this_cpu_dec(disable_stack_tracer); |
4f48f8b7 | 409 | |
e5a81b62 SR |
410 | local_irq_enable(); |
411 | } | |
412 | ||
962e3707 | 413 | static void trace_lookup_stack(struct seq_file *m, long i) |
e5a81b62 | 414 | { |
1b6cced6 | 415 | unsigned long addr = stack_dump_trace[i]; |
e5a81b62 | 416 | |
962e3707 | 417 | seq_printf(m, "%pS\n", (void *)addr); |
e5a81b62 SR |
418 | } |
419 | ||
e447e1df SR |
420 | static void print_disabled(struct seq_file *m) |
421 | { | |
422 | seq_puts(m, "#\n" | |
423 | "# Stack tracer disabled\n" | |
424 | "#\n" | |
425 | "# To enable the stack tracer, either add 'stacktrace' to the\n" | |
426 | "# kernel command line\n" | |
427 | "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n" | |
428 | "#\n"); | |
429 | } | |
430 | ||
e5a81b62 SR |
431 | static int t_show(struct seq_file *m, void *v) |
432 | { | |
522a110b | 433 | long i; |
1b6cced6 SR |
434 | int size; |
435 | ||
522a110b | 436 | if (v == SEQ_START_TOKEN) { |
eb1871f3 | 437 | seq_printf(m, " Depth Size Location" |
1b6cced6 | 438 | " (%d entries)\n" |
eb1871f3 | 439 | " ----- ---- --------\n", |
9f50c91b | 440 | stack_trace_nr_entries); |
e447e1df | 441 | |
bb99d8cc | 442 | if (!stack_tracer_enabled && !stack_trace_max_size) |
e447e1df SR |
443 | print_disabled(m); |
444 | ||
1b6cced6 SR |
445 | return 0; |
446 | } | |
e5a81b62 | 447 | |
522a110b LW |
448 | i = *(long *)v; |
449 | ||
9f50c91b | 450 | if (i >= stack_trace_nr_entries) |
e5a81b62 SR |
451 | return 0; |
452 | ||
9f50c91b | 453 | if (i + 1 == stack_trace_nr_entries) |
bb99d8cc | 454 | size = stack_trace_index[i]; |
1b6cced6 | 455 | else |
bb99d8cc | 456 | size = stack_trace_index[i] - stack_trace_index[i+1]; |
1b6cced6 | 457 | |
bb99d8cc | 458 | seq_printf(m, "%3ld) %8d %5d ", i, stack_trace_index[i], size); |
1b6cced6 SR |
459 | |
460 | trace_lookup_stack(m, i); | |
e5a81b62 SR |
461 | |
462 | return 0; | |
463 | } | |
464 | ||
f38f1d2a | 465 | static const struct seq_operations stack_trace_seq_ops = { |
e5a81b62 SR |
466 | .start = t_start, |
467 | .next = t_next, | |
468 | .stop = t_stop, | |
469 | .show = t_show, | |
470 | }; | |
471 | ||
472 | static int stack_trace_open(struct inode *inode, struct file *file) | |
473 | { | |
17911ff3 SRV |
474 | int ret; |
475 | ||
476 | ret = security_locked_down(LOCKDOWN_TRACEFS); | |
477 | if (ret) | |
478 | return ret; | |
479 | ||
d8cc1ab7 | 480 | return seq_open(file, &stack_trace_seq_ops); |
e5a81b62 SR |
481 | } |
482 | ||
f38f1d2a | 483 | static const struct file_operations stack_trace_fops = { |
e5a81b62 SR |
484 | .open = stack_trace_open, |
485 | .read = seq_read, | |
486 | .llseek = seq_lseek, | |
d8cc1ab7 | 487 | .release = seq_release, |
e5a81b62 SR |
488 | }; |
489 | ||
bbd1d27d SRV |
490 | #ifdef CONFIG_DYNAMIC_FTRACE |
491 | ||
d2d45c7a SR |
492 | static int |
493 | stack_trace_filter_open(struct inode *inode, struct file *file) | |
494 | { | |
0f179765 SRV |
495 | struct ftrace_ops *ops = inode->i_private; |
496 | ||
17911ff3 | 497 | /* Checks for tracefs lockdown */ |
0f179765 | 498 | return ftrace_regex_open(ops, FTRACE_ITER_FILTER, |
d2d45c7a SR |
499 | inode, file); |
500 | } | |
501 | ||
502 | static const struct file_operations stack_trace_filter_fops = { | |
503 | .open = stack_trace_filter_open, | |
504 | .read = seq_read, | |
505 | .write = ftrace_filter_write, | |
098c879e | 506 | .llseek = tracing_lseek, |
d2d45c7a SR |
507 | .release = ftrace_regex_release, |
508 | }; | |
509 | ||
bbd1d27d SRV |
510 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
511 | ||
f38f1d2a SR |
512 | int |
513 | stack_trace_sysctl(struct ctl_table *table, int write, | |
8d65af78 | 514 | void __user *buffer, size_t *lenp, |
f38f1d2a SR |
515 | loff_t *ppos) |
516 | { | |
3d9a8072 | 517 | int was_enabled; |
f38f1d2a SR |
518 | int ret; |
519 | ||
520 | mutex_lock(&stack_sysctl_mutex); | |
3d9a8072 | 521 | was_enabled = !!stack_tracer_enabled; |
f38f1d2a | 522 | |
8d65af78 | 523 | ret = proc_dointvec(table, write, buffer, lenp, ppos); |
f38f1d2a | 524 | |
3d9a8072 | 525 | if (ret || !write || (was_enabled == !!stack_tracer_enabled)) |
f38f1d2a SR |
526 | goto out; |
527 | ||
f38f1d2a SR |
528 | if (stack_tracer_enabled) |
529 | register_ftrace_function(&trace_ops); | |
530 | else | |
531 | unregister_ftrace_function(&trace_ops); | |
f38f1d2a SR |
532 | out: |
533 | mutex_unlock(&stack_sysctl_mutex); | |
534 | return ret; | |
535 | } | |
536 | ||
762e1207 SR |
537 | static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata; |
538 | ||
f38f1d2a SR |
539 | static __init int enable_stacktrace(char *str) |
540 | { | |
3d739c1f SRV |
541 | int len; |
542 | ||
543 | if ((len = str_has_prefix(str, "_filter="))) | |
544 | strncpy(stack_trace_filter_buf, str + len, COMMAND_LINE_SIZE); | |
762e1207 | 545 | |
e05a43b7 | 546 | stack_tracer_enabled = 1; |
f38f1d2a SR |
547 | return 1; |
548 | } | |
549 | __setup("stacktrace", enable_stacktrace); | |
550 | ||
e5a81b62 SR |
551 | static __init int stack_trace_init(void) |
552 | { | |
553 | struct dentry *d_tracer; | |
e5a81b62 SR |
554 | |
555 | d_tracer = tracing_init_dentry(); | |
14a5ae40 | 556 | if (IS_ERR(d_tracer)) |
ed6f1c99 | 557 | return 0; |
e5a81b62 | 558 | |
5452af66 | 559 | trace_create_file("stack_max_size", 0644, d_tracer, |
bb99d8cc | 560 | &stack_trace_max_size, &stack_max_size_fops); |
e5a81b62 | 561 | |
5452af66 FW |
562 | trace_create_file("stack_trace", 0444, d_tracer, |
563 | NULL, &stack_trace_fops); | |
e5a81b62 | 564 | |
bbd1d27d | 565 | #ifdef CONFIG_DYNAMIC_FTRACE |
0c5a9acc | 566 | trace_create_file("stack_trace_filter", 0644, d_tracer, |
0f179765 | 567 | &trace_ops, &stack_trace_filter_fops); |
bbd1d27d | 568 | #endif |
d2d45c7a | 569 | |
762e1207 SR |
570 | if (stack_trace_filter_buf[0]) |
571 | ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1); | |
572 | ||
e05a43b7 | 573 | if (stack_tracer_enabled) |
f38f1d2a | 574 | register_ftrace_function(&trace_ops); |
e5a81b62 SR |
575 | |
576 | return 0; | |
577 | } | |
578 | ||
579 | device_initcall(stack_trace_init); |