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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
4 *
5 */
6#include <linux/sched/task_stack.h>
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>
12#include <linux/ftrace.h>
13#include <linux/module.h>
14#include <linux/sysctl.h>
15#include <linux/init.h>
16
17#include <asm/setup.h>
18
19#include "trace.h"
20
21static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] =
22 { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
23unsigned stack_trace_index[STACK_TRACE_ENTRIES];
24
25/*
26 * Reserve one entry for the passed in ip. This will allow
27 * us to remove most or all of the stack size overhead
28 * added by the stack tracer itself.
29 */
30struct stack_trace stack_trace_max = {
31 .max_entries = STACK_TRACE_ENTRIES - 1,
32 .entries = &stack_dump_trace[0],
33};
34
35unsigned long stack_trace_max_size;
36arch_spinlock_t stack_trace_max_lock =
37 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
38
39DEFINE_PER_CPU(int, disable_stack_tracer);
40static DEFINE_MUTEX(stack_sysctl_mutex);
41
42int stack_tracer_enabled;
43static int last_stack_tracer_enabled;
44
45void stack_trace_print(void)
46{
47 long i;
48 int size;
49
50 pr_emerg(" Depth Size Location (%d entries)\n"
51 " ----- ---- --------\n",
52 stack_trace_max.nr_entries);
53
54 for (i = 0; i < stack_trace_max.nr_entries; i++) {
55 if (stack_dump_trace[i] == ULONG_MAX)
56 break;
57 if (i+1 == stack_trace_max.nr_entries ||
58 stack_dump_trace[i+1] == ULONG_MAX)
59 size = stack_trace_index[i];
60 else
61 size = stack_trace_index[i] - stack_trace_index[i+1];
62
63 pr_emerg("%3ld) %8d %5d %pS\n", i, stack_trace_index[i],
64 size, (void *)stack_dump_trace[i]);
65 }
66}
67
68/*
69 * When arch-specific code overrides this function, the following
70 * data should be filled up, assuming stack_trace_max_lock is held to
71 * prevent concurrent updates.
72 * stack_trace_index[]
73 * stack_trace_max
74 * stack_trace_max_size
75 */
76void __weak
77check_stack(unsigned long ip, unsigned long *stack)
78{
79 unsigned long this_size, flags; unsigned long *p, *top, *start;
80 static int tracer_frame;
81 int frame_size = READ_ONCE(tracer_frame);
82 int i, x;
83
84 this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
85 this_size = THREAD_SIZE - this_size;
86 /* Remove the frame of the tracer */
87 this_size -= frame_size;
88
89 if (this_size <= stack_trace_max_size)
90 return;
91
92 /* we do not handle interrupt stacks yet */
93 if (!object_is_on_stack(stack))
94 return;
95
96 /* Can't do this from NMI context (can cause deadlocks) */
97 if (in_nmi())
98 return;
99
100 local_irq_save(flags);
101 arch_spin_lock(&stack_trace_max_lock);
102
103 /* In case another CPU set the tracer_frame on us */
104 if (unlikely(!frame_size))
105 this_size -= tracer_frame;
106
107 /* a race could have already updated it */
108 if (this_size <= stack_trace_max_size)
109 goto out;
110
111 stack_trace_max_size = this_size;
112
113 stack_trace_max.nr_entries = 0;
114 stack_trace_max.skip = 3;
115
116 save_stack_trace(&stack_trace_max);
117
118 /* Skip over the overhead of the stack tracer itself */
119 for (i = 0; i < stack_trace_max.nr_entries; i++) {
120 if (stack_dump_trace[i] == ip)
121 break;
122 }
123
124 /*
125 * Some archs may not have the passed in ip in the dump.
126 * If that happens, we need to show everything.
127 */
128 if (i == stack_trace_max.nr_entries)
129 i = 0;
130
131 /*
132 * Now find where in the stack these are.
133 */
134 x = 0;
135 start = stack;
136 top = (unsigned long *)
137 (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
138
139 /*
140 * Loop through all the entries. One of the entries may
141 * for some reason be missed on the stack, so we may
142 * have to account for them. If they are all there, this
143 * loop will only happen once. This code only takes place
144 * on a new max, so it is far from a fast path.
145 */
146 while (i < stack_trace_max.nr_entries) {
147 int found = 0;
148
149 stack_trace_index[x] = this_size;
150 p = start;
151
152 for (; p < top && i < stack_trace_max.nr_entries; p++) {
153 if (stack_dump_trace[i] == ULONG_MAX)
154 break;
155 /*
156 * The READ_ONCE_NOCHECK is used to let KASAN know that
157 * this is not a stack-out-of-bounds error.
158 */
159 if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) {
160 stack_dump_trace[x] = stack_dump_trace[i++];
161 this_size = stack_trace_index[x++] =
162 (top - p) * sizeof(unsigned long);
163 found = 1;
164 /* Start the search from here */
165 start = p + 1;
166 /*
167 * We do not want to show the overhead
168 * of the stack tracer stack in the
169 * max stack. If we haven't figured
170 * out what that is, then figure it out
171 * now.
172 */
173 if (unlikely(!tracer_frame)) {
174 tracer_frame = (p - stack) *
175 sizeof(unsigned long);
176 stack_trace_max_size -= tracer_frame;
177 }
178 }
179 }
180
181 if (!found)
182 i++;
183 }
184
185 stack_trace_max.nr_entries = x;
186 for (; x < i; x++)
187 stack_dump_trace[x] = ULONG_MAX;
188
189 if (task_stack_end_corrupted(current)) {
190 stack_trace_print();
191 BUG();
192 }
193
194 out:
195 arch_spin_unlock(&stack_trace_max_lock);
196 local_irq_restore(flags);
197}
198
199static void
200stack_trace_call(unsigned long ip, unsigned long parent_ip,
201 struct ftrace_ops *op, struct pt_regs *pt_regs)
202{
203 unsigned long stack;
204
205 preempt_disable_notrace();
206
207 /* no atomic needed, we only modify this variable by this cpu */
208 __this_cpu_inc(disable_stack_tracer);
209 if (__this_cpu_read(disable_stack_tracer) != 1)
210 goto out;
211
212 /* If rcu is not watching, then save stack trace can fail */
213 if (!rcu_is_watching())
214 goto out;
215
216 ip += MCOUNT_INSN_SIZE;
217
218 check_stack(ip, &stack);
219
220 out:
221 __this_cpu_dec(disable_stack_tracer);
222 /* prevent recursion in schedule */
223 preempt_enable_notrace();
224}
225
226static struct ftrace_ops trace_ops __read_mostly =
227{
228 .func = stack_trace_call,
229 .flags = FTRACE_OPS_FL_RECURSION_SAFE,
230};
231
232static ssize_t
233stack_max_size_read(struct file *filp, char __user *ubuf,
234 size_t count, loff_t *ppos)
235{
236 unsigned long *ptr = filp->private_data;
237 char buf[64];
238 int r;
239
240 r = snprintf(buf, sizeof(buf), "%ld\n", *ptr);
241 if (r > sizeof(buf))
242 r = sizeof(buf);
243 return simple_read_from_buffer(ubuf, count, ppos, buf, r);
244}
245
246static ssize_t
247stack_max_size_write(struct file *filp, const char __user *ubuf,
248 size_t count, loff_t *ppos)
249{
250 long *ptr = filp->private_data;
251 unsigned long val, flags;
252 int ret;
253
254 ret = kstrtoul_from_user(ubuf, count, 10, &val);
255 if (ret)
256 return ret;
257
258 local_irq_save(flags);
259
260 /*
261 * In case we trace inside arch_spin_lock() or after (NMI),
262 * we will cause circular lock, so we also need to increase
263 * the percpu disable_stack_tracer here.
264 */
265 __this_cpu_inc(disable_stack_tracer);
266
267 arch_spin_lock(&stack_trace_max_lock);
268 *ptr = val;
269 arch_spin_unlock(&stack_trace_max_lock);
270
271 __this_cpu_dec(disable_stack_tracer);
272 local_irq_restore(flags);
273
274 return count;
275}
276
277static const struct file_operations stack_max_size_fops = {
278 .open = tracing_open_generic,
279 .read = stack_max_size_read,
280 .write = stack_max_size_write,
281 .llseek = default_llseek,
282};
283
284static void *
285__next(struct seq_file *m, loff_t *pos)
286{
287 long n = *pos - 1;
288
289 if (n > stack_trace_max.nr_entries || stack_dump_trace[n] == ULONG_MAX)
290 return NULL;
291
292 m->private = (void *)n;
293 return &m->private;
294}
295
296static void *
297t_next(struct seq_file *m, void *v, loff_t *pos)
298{
299 (*pos)++;
300 return __next(m, pos);
301}
302
303static void *t_start(struct seq_file *m, loff_t *pos)
304{
305 local_irq_disable();
306
307 __this_cpu_inc(disable_stack_tracer);
308
309 arch_spin_lock(&stack_trace_max_lock);
310
311 if (*pos == 0)
312 return SEQ_START_TOKEN;
313
314 return __next(m, pos);
315}
316
317static void t_stop(struct seq_file *m, void *p)
318{
319 arch_spin_unlock(&stack_trace_max_lock);
320
321 __this_cpu_dec(disable_stack_tracer);
322
323 local_irq_enable();
324}
325
326static void trace_lookup_stack(struct seq_file *m, long i)
327{
328 unsigned long addr = stack_dump_trace[i];
329
330 seq_printf(m, "%pS\n", (void *)addr);
331}
332
333static void print_disabled(struct seq_file *m)
334{
335 seq_puts(m, "#\n"
336 "# Stack tracer disabled\n"
337 "#\n"
338 "# To enable the stack tracer, either add 'stacktrace' to the\n"
339 "# kernel command line\n"
340 "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n"
341 "#\n");
342}
343
344static int t_show(struct seq_file *m, void *v)
345{
346 long i;
347 int size;
348
349 if (v == SEQ_START_TOKEN) {
350 seq_printf(m, " Depth Size Location"
351 " (%d entries)\n"
352 " ----- ---- --------\n",
353 stack_trace_max.nr_entries);
354
355 if (!stack_tracer_enabled && !stack_trace_max_size)
356 print_disabled(m);
357
358 return 0;
359 }
360
361 i = *(long *)v;
362
363 if (i >= stack_trace_max.nr_entries ||
364 stack_dump_trace[i] == ULONG_MAX)
365 return 0;
366
367 if (i+1 == stack_trace_max.nr_entries ||
368 stack_dump_trace[i+1] == ULONG_MAX)
369 size = stack_trace_index[i];
370 else
371 size = stack_trace_index[i] - stack_trace_index[i+1];
372
373 seq_printf(m, "%3ld) %8d %5d ", i, stack_trace_index[i], size);
374
375 trace_lookup_stack(m, i);
376
377 return 0;
378}
379
380static const struct seq_operations stack_trace_seq_ops = {
381 .start = t_start,
382 .next = t_next,
383 .stop = t_stop,
384 .show = t_show,
385};
386
387static int stack_trace_open(struct inode *inode, struct file *file)
388{
389 return seq_open(file, &stack_trace_seq_ops);
390}
391
392static const struct file_operations stack_trace_fops = {
393 .open = stack_trace_open,
394 .read = seq_read,
395 .llseek = seq_lseek,
396 .release = seq_release,
397};
398
399#ifdef CONFIG_DYNAMIC_FTRACE
400
401static int
402stack_trace_filter_open(struct inode *inode, struct file *file)
403{
404 struct ftrace_ops *ops = inode->i_private;
405
406 return ftrace_regex_open(ops, FTRACE_ITER_FILTER,
407 inode, file);
408}
409
410static const struct file_operations stack_trace_filter_fops = {
411 .open = stack_trace_filter_open,
412 .read = seq_read,
413 .write = ftrace_filter_write,
414 .llseek = tracing_lseek,
415 .release = ftrace_regex_release,
416};
417
418#endif /* CONFIG_DYNAMIC_FTRACE */
419
420int
421stack_trace_sysctl(struct ctl_table *table, int write,
422 void __user *buffer, size_t *lenp,
423 loff_t *ppos)
424{
425 int ret;
426
427 mutex_lock(&stack_sysctl_mutex);
428
429 ret = proc_dointvec(table, write, buffer, lenp, ppos);
430
431 if (ret || !write ||
432 (last_stack_tracer_enabled == !!stack_tracer_enabled))
433 goto out;
434
435 last_stack_tracer_enabled = !!stack_tracer_enabled;
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
447static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata;
448
449static __init int enable_stacktrace(char *str)
450{
451 if (strncmp(str, "_filter=", 8) == 0)
452 strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE);
453
454 stack_tracer_enabled = 1;
455 last_stack_tracer_enabled = 1;
456 return 1;
457}
458__setup("stacktrace", enable_stacktrace);
459
460static __init int stack_trace_init(void)
461{
462 struct dentry *d_tracer;
463
464 d_tracer = tracing_init_dentry();
465 if (IS_ERR(d_tracer))
466 return 0;
467
468 trace_create_file("stack_max_size", 0644, d_tracer,
469 &stack_trace_max_size, &stack_max_size_fops);
470
471 trace_create_file("stack_trace", 0444, d_tracer,
472 NULL, &stack_trace_fops);
473
474#ifdef CONFIG_DYNAMIC_FTRACE
475 trace_create_file("stack_trace_filter", 0644, d_tracer,
476 &trace_ops, &stack_trace_filter_fops);
477#endif
478
479 if (stack_trace_filter_buf[0])
480 ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);
481
482 if (stack_tracer_enabled)
483 register_ftrace_function(&trace_ops);
484
485 return 0;
486}
487
488device_initcall(stack_trace_init);
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>
13#include <linux/sysctl.h>
14#include <linux/init.h>
15#include <linux/fs.h>
16#include <linux/magic.h>
17
18#include <asm/setup.h>
19
20#include "trace.h"
21
22#define STACK_TRACE_ENTRIES 500
23
24#ifdef CC_USING_FENTRY
25# define fentry 1
26#else
27# define fentry 0
28#endif
29
30static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] =
31 { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
32static unsigned stack_dump_index[STACK_TRACE_ENTRIES];
33
34/*
35 * Reserve one entry for the passed in ip. This will allow
36 * us to remove most or all of the stack size overhead
37 * added by the stack tracer itself.
38 */
39static struct stack_trace max_stack_trace = {
40 .max_entries = STACK_TRACE_ENTRIES - 1,
41 .entries = &stack_dump_trace[1],
42};
43
44static unsigned long max_stack_size;
45static arch_spinlock_t max_stack_lock =
46 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
47
48static DEFINE_PER_CPU(int, trace_active);
49static DEFINE_MUTEX(stack_sysctl_mutex);
50
51int stack_tracer_enabled;
52static int last_stack_tracer_enabled;
53
54static inline void
55check_stack(unsigned long ip, unsigned long *stack)
56{
57 unsigned long this_size, flags;
58 unsigned long *p, *top, *start;
59 static int tracer_frame;
60 int frame_size = ACCESS_ONCE(tracer_frame);
61 int i;
62
63 this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
64 this_size = THREAD_SIZE - this_size;
65 /* Remove the frame of the tracer */
66 this_size -= frame_size;
67
68 if (this_size <= max_stack_size)
69 return;
70
71 /* we do not handle interrupt stacks yet */
72 if (!object_is_on_stack(stack))
73 return;
74
75 local_irq_save(flags);
76 arch_spin_lock(&max_stack_lock);
77
78 /* In case another CPU set the tracer_frame on us */
79 if (unlikely(!frame_size))
80 this_size -= tracer_frame;
81
82 /* a race could have already updated it */
83 if (this_size <= max_stack_size)
84 goto out;
85
86 max_stack_size = this_size;
87
88 max_stack_trace.nr_entries = 0;
89 max_stack_trace.skip = 3;
90
91 save_stack_trace(&max_stack_trace);
92
93 /*
94 * Add the passed in ip from the function tracer.
95 * Searching for this on the stack will skip over
96 * most of the overhead from the stack tracer itself.
97 */
98 stack_dump_trace[0] = ip;
99 max_stack_trace.nr_entries++;
100
101 /*
102 * Now find where in the stack these are.
103 */
104 i = 0;
105 start = stack;
106 top = (unsigned long *)
107 (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
108
109 /*
110 * Loop through all the entries. One of the entries may
111 * for some reason be missed on the stack, so we may
112 * have to account for them. If they are all there, this
113 * loop will only happen once. This code only takes place
114 * on a new max, so it is far from a fast path.
115 */
116 while (i < max_stack_trace.nr_entries) {
117 int found = 0;
118
119 stack_dump_index[i] = this_size;
120 p = start;
121
122 for (; p < top && i < max_stack_trace.nr_entries; p++) {
123 if (*p == stack_dump_trace[i]) {
124 this_size = stack_dump_index[i++] =
125 (top - p) * sizeof(unsigned long);
126 found = 1;
127 /* Start the search from here */
128 start = p + 1;
129 /*
130 * We do not want to show the overhead
131 * of the stack tracer stack in the
132 * max stack. If we haven't figured
133 * out what that is, then figure it out
134 * now.
135 */
136 if (unlikely(!tracer_frame) && i == 1) {
137 tracer_frame = (p - stack) *
138 sizeof(unsigned long);
139 max_stack_size -= tracer_frame;
140 }
141 }
142 }
143
144 if (!found)
145 i++;
146 }
147
148 BUG_ON(current != &init_task &&
149 *(end_of_stack(current)) != STACK_END_MAGIC);
150 out:
151 arch_spin_unlock(&max_stack_lock);
152 local_irq_restore(flags);
153}
154
155static void
156stack_trace_call(unsigned long ip, unsigned long parent_ip,
157 struct ftrace_ops *op, struct pt_regs *pt_regs)
158{
159 unsigned long stack;
160 int cpu;
161
162 preempt_disable_notrace();
163
164 cpu = raw_smp_processor_id();
165 /* no atomic needed, we only modify this variable by this cpu */
166 if (per_cpu(trace_active, cpu)++ != 0)
167 goto out;
168
169 /*
170 * When fentry is used, the traced function does not get
171 * its stack frame set up, and we lose the parent.
172 * The ip is pretty useless because the function tracer
173 * was called before that function set up its stack frame.
174 * In this case, we use the parent ip.
175 *
176 * By adding the return address of either the parent ip
177 * or the current ip we can disregard most of the stack usage
178 * caused by the stack tracer itself.
179 *
180 * The function tracer always reports the address of where the
181 * mcount call was, but the stack will hold the return address.
182 */
183 if (fentry)
184 ip = parent_ip;
185 else
186 ip += MCOUNT_INSN_SIZE;
187
188 check_stack(ip, &stack);
189
190 out:
191 per_cpu(trace_active, cpu)--;
192 /* prevent recursion in schedule */
193 preempt_enable_notrace();
194}
195
196static struct ftrace_ops trace_ops __read_mostly =
197{
198 .func = stack_trace_call,
199 .flags = FTRACE_OPS_FL_RECURSION_SAFE,
200};
201
202static ssize_t
203stack_max_size_read(struct file *filp, char __user *ubuf,
204 size_t count, loff_t *ppos)
205{
206 unsigned long *ptr = filp->private_data;
207 char buf[64];
208 int r;
209
210 r = snprintf(buf, sizeof(buf), "%ld\n", *ptr);
211 if (r > sizeof(buf))
212 r = sizeof(buf);
213 return simple_read_from_buffer(ubuf, count, ppos, buf, r);
214}
215
216static ssize_t
217stack_max_size_write(struct file *filp, const char __user *ubuf,
218 size_t count, loff_t *ppos)
219{
220 long *ptr = filp->private_data;
221 unsigned long val, flags;
222 int ret;
223 int cpu;
224
225 ret = kstrtoul_from_user(ubuf, count, 10, &val);
226 if (ret)
227 return ret;
228
229 local_irq_save(flags);
230
231 /*
232 * In case we trace inside arch_spin_lock() or after (NMI),
233 * we will cause circular lock, so we also need to increase
234 * the percpu trace_active here.
235 */
236 cpu = smp_processor_id();
237 per_cpu(trace_active, cpu)++;
238
239 arch_spin_lock(&max_stack_lock);
240 *ptr = val;
241 arch_spin_unlock(&max_stack_lock);
242
243 per_cpu(trace_active, cpu)--;
244 local_irq_restore(flags);
245
246 return count;
247}
248
249static const struct file_operations stack_max_size_fops = {
250 .open = tracing_open_generic,
251 .read = stack_max_size_read,
252 .write = stack_max_size_write,
253 .llseek = default_llseek,
254};
255
256static void *
257__next(struct seq_file *m, loff_t *pos)
258{
259 long n = *pos - 1;
260
261 if (n >= max_stack_trace.nr_entries || stack_dump_trace[n] == ULONG_MAX)
262 return NULL;
263
264 m->private = (void *)n;
265 return &m->private;
266}
267
268static void *
269t_next(struct seq_file *m, void *v, loff_t *pos)
270{
271 (*pos)++;
272 return __next(m, pos);
273}
274
275static void *t_start(struct seq_file *m, loff_t *pos)
276{
277 int cpu;
278
279 local_irq_disable();
280
281 cpu = smp_processor_id();
282 per_cpu(trace_active, cpu)++;
283
284 arch_spin_lock(&max_stack_lock);
285
286 if (*pos == 0)
287 return SEQ_START_TOKEN;
288
289 return __next(m, pos);
290}
291
292static void t_stop(struct seq_file *m, void *p)
293{
294 int cpu;
295
296 arch_spin_unlock(&max_stack_lock);
297
298 cpu = smp_processor_id();
299 per_cpu(trace_active, cpu)--;
300
301 local_irq_enable();
302}
303
304static int trace_lookup_stack(struct seq_file *m, long i)
305{
306 unsigned long addr = stack_dump_trace[i];
307
308 return seq_printf(m, "%pS\n", (void *)addr);
309}
310
311static void print_disabled(struct seq_file *m)
312{
313 seq_puts(m, "#\n"
314 "# Stack tracer disabled\n"
315 "#\n"
316 "# To enable the stack tracer, either add 'stacktrace' to the\n"
317 "# kernel command line\n"
318 "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n"
319 "#\n");
320}
321
322static int t_show(struct seq_file *m, void *v)
323{
324 long i;
325 int size;
326
327 if (v == SEQ_START_TOKEN) {
328 seq_printf(m, " Depth Size Location"
329 " (%d entries)\n"
330 " ----- ---- --------\n",
331 max_stack_trace.nr_entries - 1);
332
333 if (!stack_tracer_enabled && !max_stack_size)
334 print_disabled(m);
335
336 return 0;
337 }
338
339 i = *(long *)v;
340
341 if (i >= max_stack_trace.nr_entries ||
342 stack_dump_trace[i] == ULONG_MAX)
343 return 0;
344
345 if (i+1 == max_stack_trace.nr_entries ||
346 stack_dump_trace[i+1] == ULONG_MAX)
347 size = stack_dump_index[i];
348 else
349 size = stack_dump_index[i] - stack_dump_index[i+1];
350
351 seq_printf(m, "%3ld) %8d %5d ", i, stack_dump_index[i], size);
352
353 trace_lookup_stack(m, i);
354
355 return 0;
356}
357
358static const struct seq_operations stack_trace_seq_ops = {
359 .start = t_start,
360 .next = t_next,
361 .stop = t_stop,
362 .show = t_show,
363};
364
365static int stack_trace_open(struct inode *inode, struct file *file)
366{
367 return seq_open(file, &stack_trace_seq_ops);
368}
369
370static const struct file_operations stack_trace_fops = {
371 .open = stack_trace_open,
372 .read = seq_read,
373 .llseek = seq_lseek,
374 .release = seq_release,
375};
376
377static int
378stack_trace_filter_open(struct inode *inode, struct file *file)
379{
380 return ftrace_regex_open(&trace_ops, FTRACE_ITER_FILTER,
381 inode, file);
382}
383
384static const struct file_operations stack_trace_filter_fops = {
385 .open = stack_trace_filter_open,
386 .read = seq_read,
387 .write = ftrace_filter_write,
388 .llseek = tracing_lseek,
389 .release = ftrace_regex_release,
390};
391
392int
393stack_trace_sysctl(struct ctl_table *table, int write,
394 void __user *buffer, size_t *lenp,
395 loff_t *ppos)
396{
397 int ret;
398
399 mutex_lock(&stack_sysctl_mutex);
400
401 ret = proc_dointvec(table, write, buffer, lenp, ppos);
402
403 if (ret || !write ||
404 (last_stack_tracer_enabled == !!stack_tracer_enabled))
405 goto out;
406
407 last_stack_tracer_enabled = !!stack_tracer_enabled;
408
409 if (stack_tracer_enabled)
410 register_ftrace_function(&trace_ops);
411 else
412 unregister_ftrace_function(&trace_ops);
413
414 out:
415 mutex_unlock(&stack_sysctl_mutex);
416 return ret;
417}
418
419static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata;
420
421static __init int enable_stacktrace(char *str)
422{
423 if (strncmp(str, "_filter=", 8) == 0)
424 strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE);
425
426 stack_tracer_enabled = 1;
427 last_stack_tracer_enabled = 1;
428 return 1;
429}
430__setup("stacktrace", enable_stacktrace);
431
432static __init int stack_trace_init(void)
433{
434 struct dentry *d_tracer;
435
436 d_tracer = tracing_init_dentry();
437 if (!d_tracer)
438 return 0;
439
440 trace_create_file("stack_max_size", 0644, d_tracer,
441 &max_stack_size, &stack_max_size_fops);
442
443 trace_create_file("stack_trace", 0444, d_tracer,
444 NULL, &stack_trace_fops);
445
446 trace_create_file("stack_trace_filter", 0444, d_tracer,
447 NULL, &stack_trace_filter_fops);
448
449 if (stack_trace_filter_buf[0])
450 ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);
451
452 if (stack_tracer_enabled)
453 register_ftrace_function(&trace_ops);
454
455 return 0;
456}
457
458device_initcall(stack_trace_init);