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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * trace_events_trigger - trace event triggers
4 *
5 * Copyright (C) 2013 Tom Zanussi <[email protected]>
6 */
7
8#include <linux/security.h>
9#include <linux/kthread.h>
10#include <linux/module.h>
11#include <linux/ctype.h>
12#include <linux/mutex.h>
13#include <linux/slab.h>
14#include <linux/rculist.h>
15
16#include "trace.h"
17
18static LIST_HEAD(trigger_commands);
19static DEFINE_MUTEX(trigger_cmd_mutex);
20
21static struct task_struct *trigger_kthread;
22static struct llist_head trigger_data_free_list;
23static DEFINE_MUTEX(trigger_data_kthread_mutex);
24
25static int trigger_kthread_fn(void *ignore);
26
27static void trigger_create_kthread_locked(void)
28{
29 lockdep_assert_held(&trigger_data_kthread_mutex);
30
31 if (!trigger_kthread) {
32 struct task_struct *kthread;
33
34 kthread = kthread_create(trigger_kthread_fn, NULL,
35 "trigger_data_free");
36 if (!IS_ERR(kthread))
37 WRITE_ONCE(trigger_kthread, kthread);
38 }
39}
40
41static void trigger_data_free_one(struct event_trigger_data *data)
42{
43 if (data->private_data_free)
44 data->private_data_free(data);
45 kfree(data);
46}
47
48static void trigger_data_free_queued_locked(void)
49{
50 struct event_trigger_data *data, *tmp;
51 struct llist_node *llnodes;
52
53 lockdep_assert_held(&trigger_data_kthread_mutex);
54
55 llnodes = llist_del_all(&trigger_data_free_list);
56 if (!llnodes)
57 return;
58
59 tracepoint_synchronize_unregister();
60
61 llist_for_each_entry_safe(data, tmp, llnodes, llist)
62 trigger_data_free_one(data);
63}
64
65/* Bulk garbage collection of event_trigger_data elements */
66static int trigger_kthread_fn(void *ignore)
67{
68 struct event_trigger_data *data, *tmp;
69 struct llist_node *llnodes;
70
71 /* Once this task starts, it lives forever */
72 for (;;) {
73 set_current_state(TASK_INTERRUPTIBLE);
74 if (llist_empty(&trigger_data_free_list))
75 schedule();
76
77 __set_current_state(TASK_RUNNING);
78
79 llnodes = llist_del_all(&trigger_data_free_list);
80
81 /* make sure current triggers exit before free */
82 tracepoint_synchronize_unregister();
83
84 llist_for_each_entry_safe(data, tmp, llnodes, llist)
85 trigger_data_free_one(data);
86 }
87
88 return 0;
89}
90
91void trigger_data_free(struct event_trigger_data *data)
92{
93 if (!data)
94 return;
95
96 if (data->cmd_ops->set_filter)
97 data->cmd_ops->set_filter(NULL, data, NULL);
98
99 /*
100 * Boot-time trigger registration can fail before kthread creation
101 * works. Keep the deferred-free semantics during boot and let late
102 * init start the kthread to drain the list.
103 */
104 if (system_state == SYSTEM_BOOTING && !trigger_kthread) {
105 llist_add(&data->llist, &trigger_data_free_list);
106 return;
107 }
108
109 if (unlikely(!trigger_kthread)) {
110 guard(mutex)(&trigger_data_kthread_mutex);
111
112 trigger_create_kthread_locked();
113 /* Check again after taking mutex */
114 if (!trigger_kthread) {
115 llist_add(&data->llist, &trigger_data_free_list);
116 /* Drain the queued frees synchronously if creation failed. */
117 trigger_data_free_queued_locked();
118 return;
119 }
120 }
121
122 llist_add(&data->llist, &trigger_data_free_list);
123 wake_up_process(trigger_kthread);
124}
125
126static int __init trigger_data_free_init(void)
127{
128 guard(mutex)(&trigger_data_kthread_mutex);
129
130 if (llist_empty(&trigger_data_free_list))
131 return 0;
132
133 trigger_create_kthread_locked();
134 if (trigger_kthread)
135 wake_up_process(trigger_kthread);
136 else
137 trigger_data_free_queued_locked();
138
139 return 0;
140}
141late_initcall(trigger_data_free_init);
142
143static inline void data_ops_trigger(struct event_trigger_data *data,
144 struct trace_buffer *buffer, void *rec,
145 struct ring_buffer_event *event)
146{
147 const struct event_command *cmd_ops = data->cmd_ops;
148
149 if (data->flags & EVENT_TRIGGER_FL_COUNT) {
150 if (!cmd_ops->count_func(data, buffer, rec, event))
151 return;
152 }
153
154 cmd_ops->trigger(data, buffer, rec, event);
155}
156
157/**
158 * event_triggers_call - Call triggers associated with a trace event
159 * @file: The trace_event_file associated with the event
160 * @buffer: The ring buffer that the event is being written to
161 * @rec: The trace entry for the event, NULL for unconditional invocation
162 * @event: The event meta data in the ring buffer
163 *
164 * For each trigger associated with an event, invoke the trigger
165 * function registered with the associated trigger command. If rec is
166 * non-NULL, it means that the trigger requires further processing and
167 * shouldn't be unconditionally invoked. If rec is non-NULL and the
168 * trigger has a filter associated with it, rec will checked against
169 * the filter and if the record matches the trigger will be invoked.
170 * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
171 * in any case until the current event is written, the trigger
172 * function isn't invoked but the bit associated with the deferred
173 * trigger is set in the return value.
174 *
175 * Returns an enum event_trigger_type value containing a set bit for
176 * any trigger that should be deferred, ETT_NONE if nothing to defer.
177 *
178 * Called from tracepoint handlers (with rcu_read_lock_sched() held).
179 *
180 * Return: an enum event_trigger_type value containing a set bit for
181 * any trigger that should be deferred, ETT_NONE if nothing to defer.
182 */
183enum event_trigger_type
184event_triggers_call(struct trace_event_file *file,
185 struct trace_buffer *buffer, void *rec,
186 struct ring_buffer_event *event)
187{
188 struct event_trigger_data *data;
189 enum event_trigger_type tt = ETT_NONE;
190 struct event_filter *filter;
191
192 if (list_empty(&file->triggers))
193 return tt;
194
195 list_for_each_entry_rcu(data, &file->triggers, list) {
196 if (data->paused)
197 continue;
198 if (!rec) {
199 data_ops_trigger(data, buffer, rec, event);
200 continue;
201 }
202 filter = rcu_dereference_sched(data->filter);
203 if (filter && !filter_match_preds(filter, rec))
204 continue;
205 if (event_command_post_trigger(data->cmd_ops)) {
206 tt |= data->cmd_ops->trigger_type;
207 continue;
208 }
209 data_ops_trigger(data, buffer, rec, event);
210 }
211 return tt;
212}
213EXPORT_SYMBOL_GPL(event_triggers_call);
214
215bool __trace_trigger_soft_disabled(struct trace_event_file *file)
216{
217 unsigned long eflags = file->flags;
218
219 if (eflags & EVENT_FILE_FL_TRIGGER_MODE)
220 event_triggers_call(file, NULL, NULL, NULL);
221 if (eflags & EVENT_FILE_FL_SOFT_DISABLED)
222 return true;
223 if (eflags & EVENT_FILE_FL_PID_FILTER)
224 return trace_event_ignore_this_pid(file);
225 return false;
226}
227EXPORT_SYMBOL_GPL(__trace_trigger_soft_disabled);
228
229/**
230 * event_triggers_post_call - Call 'post_triggers' for a trace event
231 * @file: The trace_event_file associated with the event
232 * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
233 *
234 * For each trigger associated with an event, invoke the trigger
235 * function registered with the associated trigger command, if the
236 * corresponding bit is set in the tt enum passed into this function.
237 * See @event_triggers_call for details on how those bits are set.
238 *
239 * Called from tracepoint handlers (with rcu_read_lock_sched() held).
240 */
241void
242event_triggers_post_call(struct trace_event_file *file,
243 enum event_trigger_type tt)
244{
245 struct event_trigger_data *data;
246
247 list_for_each_entry_rcu(data, &file->triggers, list) {
248 if (data->paused)
249 continue;
250 if (data->cmd_ops->trigger_type & tt)
251 data_ops_trigger(data, NULL, NULL, NULL);
252 }
253}
254EXPORT_SYMBOL_GPL(event_triggers_post_call);
255
256#define SHOW_AVAILABLE_TRIGGERS (void *)(1UL)
257
258static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
259{
260 struct trace_event_file *event_file = event_file_data(m->private);
261
262 if (t == SHOW_AVAILABLE_TRIGGERS) {
263 (*pos)++;
264 return NULL;
265 }
266 return seq_list_next(t, &event_file->triggers, pos);
267}
268
269static bool check_user_trigger(struct trace_event_file *file)
270{
271 struct event_trigger_data *data;
272
273 list_for_each_entry_rcu(data, &file->triggers, list,
274 lockdep_is_held(&event_mutex)) {
275 if (data->flags & EVENT_TRIGGER_FL_PROBE)
276 continue;
277 return true;
278 }
279 return false;
280}
281
282static void *trigger_start(struct seq_file *m, loff_t *pos)
283{
284 struct trace_event_file *event_file;
285
286 /* ->stop() is called even if ->start() fails */
287 mutex_lock(&event_mutex);
288 event_file = event_file_file(m->private);
289 if (unlikely(!event_file))
290 return ERR_PTR(-ENODEV);
291
292 if (list_empty(&event_file->triggers) || !check_user_trigger(event_file))
293 return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
294
295 return seq_list_start(&event_file->triggers, *pos);
296}
297
298static void trigger_stop(struct seq_file *m, void *t)
299{
300 mutex_unlock(&event_mutex);
301}
302
303static int trigger_show(struct seq_file *m, void *v)
304{
305 struct event_trigger_data *data;
306 struct event_command *p;
307
308 if (v == SHOW_AVAILABLE_TRIGGERS) {
309 seq_puts(m, "# Available triggers:\n");
310 seq_putc(m, '#');
311 mutex_lock(&trigger_cmd_mutex);
312 list_for_each_entry_reverse(p, &trigger_commands, list)
313 seq_printf(m, " %s", p->name);
314 seq_putc(m, '\n');
315 mutex_unlock(&trigger_cmd_mutex);
316 return 0;
317 }
318
319 data = list_entry(v, struct event_trigger_data, list);
320 data->cmd_ops->print(m, data);
321
322 return 0;
323}
324
325static const struct seq_operations event_triggers_seq_ops = {
326 .start = trigger_start,
327 .next = trigger_next,
328 .stop = trigger_stop,
329 .show = trigger_show,
330};
331
332static int event_trigger_regex_open(struct inode *inode, struct file *file)
333{
334 int ret;
335
336 ret = security_locked_down(LOCKDOWN_TRACEFS);
337 if (ret)
338 return ret;
339
340 guard(mutex)(&event_mutex);
341
342 if (unlikely(!event_file_file(file)))
343 return -ENODEV;
344
345 if ((file->f_mode & FMODE_WRITE) &&
346 (file->f_flags & O_TRUNC)) {
347 struct trace_event_file *event_file;
348 struct event_command *p;
349
350 event_file = event_file_data(file);
351
352 list_for_each_entry(p, &trigger_commands, list) {
353 if (p->unreg_all)
354 p->unreg_all(event_file);
355 }
356 }
357
358 if (file->f_mode & FMODE_READ) {
359 ret = seq_open(file, &event_triggers_seq_ops);
360 if (!ret) {
361 struct seq_file *m = file->private_data;
362 m->private = file;
363 }
364 }
365
366 return ret;
367}
368
369int trigger_process_regex(struct trace_event_file *file, char *buff)
370{
371 char *command, *next;
372 struct event_command *p;
373
374 next = buff = strim(buff);
375
376 command = strsep(&next, ": \t");
377 if (next) {
378 next = skip_spaces(next);
379 if (!*next)
380 next = NULL;
381 }
382 command = (command[0] != '!') ? command : command + 1;
383
384 guard(mutex)(&trigger_cmd_mutex);
385
386 list_for_each_entry(p, &trigger_commands, list) {
387 if (strcmp(p->name, command) == 0)
388 return p->parse(p, file, buff, command, next);
389 }
390
391 return -EINVAL;
392}
393
394static ssize_t event_trigger_regex_write(struct file *file,
395 const char __user *ubuf,
396 size_t cnt, loff_t *ppos)
397{
398 struct trace_event_file *event_file;
399 ssize_t ret;
400 char *buf __free(kfree) = NULL;
401
402 if (!cnt)
403 return 0;
404
405 if (cnt >= PAGE_SIZE)
406 return -EINVAL;
407
408 buf = memdup_user_nul(ubuf, cnt);
409 if (IS_ERR(buf))
410 return PTR_ERR(buf);
411
412 guard(mutex)(&event_mutex);
413
414 event_file = event_file_file(file);
415 if (unlikely(!event_file))
416 return -ENODEV;
417
418 ret = trigger_process_regex(event_file, buf);
419 if (ret < 0)
420 return ret;
421
422 *ppos += cnt;
423 return cnt;
424}
425
426static int event_trigger_regex_release(struct inode *inode, struct file *file)
427{
428 if (file->f_mode & FMODE_READ)
429 seq_release(inode, file);
430
431 return 0;
432}
433
434static ssize_t
435event_trigger_write(struct file *filp, const char __user *ubuf,
436 size_t cnt, loff_t *ppos)
437{
438 return event_trigger_regex_write(filp, ubuf, cnt, ppos);
439}
440
441static int
442event_trigger_open(struct inode *inode, struct file *filp)
443{
444 /* Checks for tracefs lockdown */
445 return event_trigger_regex_open(inode, filp);
446}
447
448static int
449event_trigger_release(struct inode *inode, struct file *file)
450{
451 return event_trigger_regex_release(inode, file);
452}
453
454const struct file_operations event_trigger_fops = {
455 .open = event_trigger_open,
456 .read = seq_read,
457 .write = event_trigger_write,
458 .llseek = tracing_lseek,
459 .release = event_trigger_release,
460};
461
462/*
463 * Currently we only register event commands from __init, so mark this
464 * __init too.
465 */
466__init int register_event_command(struct event_command *cmd)
467{
468 struct event_command *p;
469
470 guard(mutex)(&trigger_cmd_mutex);
471
472 list_for_each_entry(p, &trigger_commands, list) {
473 if (strcmp(cmd->name, p->name) == 0)
474 return -EBUSY;
475 }
476 list_add(&cmd->list, &trigger_commands);
477
478 return 0;
479}
480
481/*
482 * Currently we only unregister event commands from __init, so mark
483 * this __init too.
484 */
485__init int unregister_event_command(struct event_command *cmd)
486{
487 struct event_command *p, *n;
488
489 guard(mutex)(&trigger_cmd_mutex);
490
491 list_for_each_entry_safe(p, n, &trigger_commands, list) {
492 if (strcmp(cmd->name, p->name) == 0) {
493 list_del_init(&p->list);
494 return 0;
495 }
496 }
497
498 return -ENODEV;
499}
500
501/**
502 * event_trigger_count - Optional count function for event triggers
503 * @data: Trigger-specific data
504 * @buffer: The ring buffer that the event is being written to
505 * @rec: The trace entry for the event, NULL for unconditional invocation
506 * @event: The event meta data in the ring buffer
507 *
508 * For triggers that can take a count parameter that doesn't do anything
509 * special, they can use this function to assign to their .count_func
510 * field.
511 *
512 * This simply does a count down of the @data->count field.
513 *
514 * If the @data->count is greater than zero, it will decrement it.
515 *
516 * Returns false if @data->count is zero, otherwise true.
517 */
518bool event_trigger_count(struct event_trigger_data *data,
519 struct trace_buffer *buffer, void *rec,
520 struct ring_buffer_event *event)
521{
522 if (!data->count)
523 return false;
524
525 if (data->count != -1)
526 (data->count)--;
527
528 return true;
529}
530
531/**
532 * event_trigger_print - Generic event_command @print implementation
533 * @name: The name of the event trigger
534 * @m: The seq_file being printed to
535 * @data: Trigger-specific data
536 * @filter_str: filter_str to print, if present
537 *
538 * Common implementation for event triggers to print themselves.
539 *
540 * Usually wrapped by a function that simply sets the @name of the
541 * trigger command and then invokes this.
542 *
543 * Return: 0 on success, errno otherwise
544 */
545static int
546event_trigger_print(const char *name, struct seq_file *m,
547 void *data, char *filter_str)
548{
549 long count = (long)data;
550
551 seq_puts(m, name);
552
553 if (count == -1)
554 seq_puts(m, ":unlimited");
555 else
556 seq_printf(m, ":count=%ld", count);
557
558 if (filter_str)
559 seq_printf(m, " if %s\n", filter_str);
560 else
561 seq_putc(m, '\n');
562
563 return 0;
564}
565
566/**
567 * event_trigger_init - Generic event_command @init implementation
568 * @data: Trigger-specific data
569 *
570 * Common implementation of event trigger initialization.
571 *
572 * Usually used directly as the @init method in event trigger
573 * implementations.
574 *
575 * Return: 0 on success, errno otherwise
576 */
577int event_trigger_init(struct event_trigger_data *data)
578{
579 data->ref++;
580 return 0;
581}
582
583/**
584 * event_trigger_free - Generic event_command @free implementation
585 * @data: Trigger-specific data
586 *
587 * Common implementation of event trigger de-initialization.
588 *
589 * Usually used directly as the @free method in event trigger
590 * implementations.
591 */
592static void
593event_trigger_free(struct event_trigger_data *data)
594{
595 if (WARN_ON_ONCE(data->ref <= 0))
596 return;
597
598 data->ref--;
599 if (!data->ref)
600 trigger_data_free(data);
601}
602
603int trace_event_trigger_enable_disable(struct trace_event_file *file,
604 int trigger_enable)
605{
606 int ret = 0;
607
608 if (trigger_enable) {
609 if (atomic_inc_return(&file->tm_ref) > 1)
610 return ret;
611 set_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
612 ret = trace_event_enable_disable(file, 1, 1);
613 } else {
614 if (atomic_dec_return(&file->tm_ref) > 0)
615 return ret;
616 clear_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
617 ret = trace_event_enable_disable(file, 0, 1);
618 }
619
620 return ret;
621}
622
623/**
624 * clear_event_triggers - Clear all triggers associated with a trace array
625 * @tr: The trace array to clear
626 *
627 * For each trigger, the triggering event has its tm_ref decremented
628 * via trace_event_trigger_enable_disable(), and any associated event
629 * (in the case of enable/disable_event triggers) will have its sm_ref
630 * decremented via free()->trace_event_enable_disable(). That
631 * combination effectively reverses the soft-mode/trigger state added
632 * by trigger registration.
633 *
634 * Must be called with event_mutex held.
635 */
636void
637clear_event_triggers(struct trace_array *tr)
638{
639 struct trace_event_file *file;
640
641 list_for_each_entry(file, &tr->events, list) {
642 struct event_trigger_data *data, *n;
643 list_for_each_entry_safe(data, n, &file->triggers, list) {
644 trace_event_trigger_enable_disable(file, 0);
645 list_del_rcu(&data->list);
646 if (data->cmd_ops->free)
647 data->cmd_ops->free(data);
648 }
649 }
650}
651
652/**
653 * update_cond_flag - Set or reset the TRIGGER_COND bit
654 * @file: The trace_event_file associated with the event
655 *
656 * If an event has triggers and any of those triggers has a filter or
657 * a post_trigger, trigger invocation needs to be deferred until after
658 * the current event has logged its data, and the event should have
659 * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
660 * cleared.
661 */
662void update_cond_flag(struct trace_event_file *file)
663{
664 struct event_trigger_data *data;
665 bool set_cond = false;
666
667 lockdep_assert_held(&event_mutex);
668
669 list_for_each_entry(data, &file->triggers, list) {
670 if (data->filter || event_command_post_trigger(data->cmd_ops) ||
671 event_command_needs_rec(data->cmd_ops)) {
672 set_cond = true;
673 break;
674 }
675 }
676
677 if (set_cond)
678 set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
679 else
680 clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
681}
682
683/**
684 * register_trigger - Generic event_command @reg implementation
685 * @glob: The raw string used to register the trigger
686 * @data: Trigger-specific data to associate with the trigger
687 * @file: The trace_event_file associated with the event
688 *
689 * Common implementation for event trigger registration.
690 *
691 * Usually used directly as the @reg method in event command
692 * implementations.
693 *
694 * Return: 0 on success, errno otherwise
695 */
696static int register_trigger(char *glob,
697 struct event_trigger_data *data,
698 struct trace_event_file *file)
699{
700 struct event_trigger_data *test;
701 int ret = 0;
702
703 lockdep_assert_held(&event_mutex);
704
705 list_for_each_entry(test, &file->triggers, list) {
706 if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type)
707 return -EEXIST;
708 }
709
710 if (data->cmd_ops->init) {
711 ret = data->cmd_ops->init(data);
712 if (ret < 0)
713 return ret;
714 }
715
716 list_add_rcu(&data->list, &file->triggers);
717
718 update_cond_flag(file);
719 ret = trace_event_trigger_enable_disable(file, 1);
720 if (ret < 0) {
721 list_del_rcu(&data->list);
722 update_cond_flag(file);
723 }
724 return ret;
725}
726
727/*
728 * True if the trigger was found and unregistered, else false.
729 */
730static bool try_unregister_trigger(char *glob,
731 struct event_trigger_data *test,
732 struct trace_event_file *file)
733{
734 struct event_trigger_data *data = NULL, *iter;
735
736 lockdep_assert_held(&event_mutex);
737
738 list_for_each_entry(iter, &file->triggers, list) {
739 if (iter->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
740 data = iter;
741 list_del_rcu(&data->list);
742 trace_event_trigger_enable_disable(file, 0);
743 update_cond_flag(file);
744 break;
745 }
746 }
747
748 if (data) {
749 if (data->cmd_ops->free)
750 data->cmd_ops->free(data);
751
752 return true;
753 }
754
755 return false;
756}
757
758/**
759 * unregister_trigger - Generic event_command @unreg implementation
760 * @glob: The raw string used to register the trigger
761 * @test: Trigger-specific data used to find the trigger to remove
762 * @file: The trace_event_file associated with the event
763 *
764 * Common implementation for event trigger unregistration.
765 *
766 * Usually used directly as the @unreg method in event command
767 * implementations.
768 */
769static void unregister_trigger(char *glob,
770 struct event_trigger_data *test,
771 struct trace_event_file *file)
772{
773 try_unregister_trigger(glob, test, file);
774}
775
776/*
777 * Event trigger parsing helper functions.
778 *
779 * These functions help make it easier to write an event trigger
780 * parsing function i.e. the struct event_command.parse() callback
781 * function responsible for parsing and registering a trigger command
782 * written to the 'trigger' file.
783 *
784 * A trigger command (or just 'trigger' for short) takes the form:
785 * [trigger] [if filter]
786 *
787 * The struct event_command.parse() callback (and other struct
788 * event_command functions) refer to several components of a trigger
789 * command. Those same components are referenced by the event trigger
790 * parsing helper functions defined below. These components are:
791 *
792 * cmd - the trigger command name
793 * glob - the trigger command name optionally prefaced with '!'
794 * param_and_filter - text following cmd and ':'
795 * param - text following cmd and ':' and stripped of filter
796 * filter - the optional filter text following (and including) 'if'
797 *
798 * To illustrate the use of these components, here are some concrete
799 * examples. For the following triggers:
800 *
801 * echo 'traceon:5 if pid == 0' > trigger
802 * - 'traceon' is both cmd and glob
803 * - '5 if pid == 0' is the param_and_filter
804 * - '5' is the param
805 * - 'if pid == 0' is the filter
806 *
807 * echo 'enable_event:sys:event:n' > trigger
808 * - 'enable_event' is both cmd and glob
809 * - 'sys:event:n' is the param_and_filter
810 * - 'sys:event:n' is the param
811 * - there is no filter
812 *
813 * echo 'hist:keys=pid if prio > 50' > trigger
814 * - 'hist' is both cmd and glob
815 * - 'keys=pid if prio > 50' is the param_and_filter
816 * - 'keys=pid' is the param
817 * - 'if prio > 50' is the filter
818 *
819 * echo '!enable_event:sys:event:n' > trigger
820 * - 'enable_event' the cmd
821 * - '!enable_event' is the glob
822 * - 'sys:event:n' is the param_and_filter
823 * - 'sys:event:n' is the param
824 * - there is no filter
825 *
826 * echo 'traceoff' > trigger
827 * - 'traceoff' is both cmd and glob
828 * - there is no param_and_filter
829 * - there is no param
830 * - there is no filter
831 *
832 * There are a few different categories of event trigger covered by
833 * these helpers:
834 *
835 * - triggers that don't require a parameter e.g. traceon
836 * - triggers that do require a parameter e.g. enable_event and hist
837 * - triggers that though they may not require a param may support an
838 * optional 'n' param (n = number of times the trigger should fire)
839 * e.g.: traceon:5 or enable_event:sys:event:n
840 * - triggers that do not support an 'n' param e.g. hist
841 *
842 * These functions can be used or ignored as necessary - it all
843 * depends on the complexity of the trigger, and the granularity of
844 * the functions supported reflects the fact that some implementations
845 * may need to customize certain aspects of their implementations and
846 * won't need certain functions. For instance, the hist trigger
847 * implementation doesn't use event_trigger_separate_filter() because
848 * it has special requirements for handling the filter.
849 */
850
851/**
852 * event_trigger_check_remove - check whether an event trigger specifies remove
853 * @glob: The trigger command string, with optional remove(!) operator
854 *
855 * The event trigger callback implementations pass in 'glob' as a
856 * parameter. This is the command name either with or without a
857 * remove(!) operator. This function simply parses the glob and
858 * determines whether the command corresponds to a trigger removal or
859 * a trigger addition.
860 *
861 * Return: true if this is a remove command, false otherwise
862 */
863bool event_trigger_check_remove(const char *glob)
864{
865 return (glob && glob[0] == '!') ? true : false;
866}
867
868/**
869 * event_trigger_empty_param - check whether the param is empty
870 * @param: The trigger param string
871 *
872 * The event trigger callback implementations pass in 'param' as a
873 * parameter. This corresponds to the string following the command
874 * name minus the command name. This function can be called by a
875 * callback implementation for any command that requires a param; a
876 * callback that doesn't require a param can ignore it.
877 *
878 * Return: true if this is an empty param, false otherwise
879 */
880bool event_trigger_empty_param(const char *param)
881{
882 return !param;
883}
884
885/**
886 * event_trigger_separate_filter - separate an event trigger from a filter
887 * @param_and_filter: String containing trigger and possibly filter
888 * @param: outparam, will be filled with a pointer to the trigger
889 * @filter: outparam, will be filled with a pointer to the filter
890 * @param_required: Specifies whether or not the param string is required
891 *
892 * Given a param string of the form '[trigger] [if filter]', this
893 * function separates the filter from the trigger and returns the
894 * trigger in @param and the filter in @filter. Either the @param
895 * or the @filter may be set to NULL by this function - if not set to
896 * NULL, they will contain strings corresponding to the trigger and
897 * filter.
898 *
899 * There are two cases that need to be handled with respect to the
900 * passed-in param: either the param is required, or it is not
901 * required. If @param_required is set, and there's no param, it will
902 * return -EINVAL. If @param_required is not set and there's a param
903 * that starts with a number, that corresponds to the case of a
904 * trigger with :n (n = number of times the trigger should fire) and
905 * the parsing continues normally; otherwise the function just returns
906 * and assumes param just contains a filter and there's nothing else
907 * to do.
908 *
909 * Return: 0 on success, errno otherwise
910 */
911int event_trigger_separate_filter(char *param_and_filter, char **param,
912 char **filter, bool param_required)
913{
914 int ret = 0;
915
916 *param = *filter = NULL;
917
918 if (!param_and_filter) {
919 if (param_required)
920 ret = -EINVAL;
921 return ret;
922 }
923
924 /*
925 * Here we check for an optional param. The only legal
926 * optional param is :n, and if that's the case, continue
927 * below. Otherwise we assume what's left is a filter and
928 * return it as the filter string for the caller to deal with.
929 */
930 if (!param_required && param_and_filter && !isdigit(param_and_filter[0])) {
931 *filter = param_and_filter;
932 return ret;
933 }
934
935 /*
936 * Separate the param from the filter (param [if filter]).
937 * Here we have either an optional :n param or a required
938 * param and an optional filter.
939 */
940 *param = strsep(&param_and_filter, " \t");
941
942 /*
943 * Here we have a filter, though it may be empty.
944 */
945 if (param_and_filter) {
946 *filter = skip_spaces(param_and_filter);
947 if (!**filter)
948 *filter = NULL;
949 }
950 return ret;
951}
952
953/**
954 * trigger_data_alloc - allocate and init event_trigger_data for a trigger
955 * @cmd_ops: The event_command operations for the trigger
956 * @cmd: The cmd string
957 * @param: The param string
958 * @private_data: User data to associate with the event trigger
959 *
960 * Allocate an event_trigger_data instance and initialize it. The
961 * @cmd_ops defines how the trigger will operate. If @param is set,
962 * and @cmd_ops->trigger_ops->count_func is non NULL, then the
963 * data->count is set to @param and before the trigger is executed, the
964 * @cmd_ops->trigger_ops->count_func() is called. If that function returns
965 * false, the @cmd_ops->trigger_ops->trigger() function will not be called.
966 * @private_data can also be passed in and associated with the
967 * event_trigger_data.
968 *
969 * Use trigger_data_free() to free an event_trigger_data object.
970 *
971 * Return: The trigger_data object success, NULL otherwise
972 */
973struct event_trigger_data *trigger_data_alloc(struct event_command *cmd_ops,
974 char *cmd,
975 char *param,
976 void *private_data)
977{
978 struct event_trigger_data *trigger_data;
979
980 trigger_data = kzalloc_obj(*trigger_data);
981 if (!trigger_data)
982 return NULL;
983
984 trigger_data->count = -1;
985 trigger_data->cmd_ops = cmd_ops;
986 trigger_data->private_data = private_data;
987 if (param && cmd_ops->count_func)
988 trigger_data->flags |= EVENT_TRIGGER_FL_COUNT;
989
990 INIT_LIST_HEAD(&trigger_data->list);
991 INIT_LIST_HEAD(&trigger_data->named_list);
992 RCU_INIT_POINTER(trigger_data->filter, NULL);
993
994 return trigger_data;
995}
996
997/**
998 * event_trigger_parse_num - parse and return the number param for a trigger
999 * @param: The param string
1000 * @trigger_data: The trigger_data for the trigger
1001 *
1002 * Parse the :n (n = number of times the trigger should fire) param
1003 * and set the count variable in the trigger_data to the parsed count.
1004 *
1005 * Return: 0 on success, errno otherwise
1006 */
1007int event_trigger_parse_num(char *param,
1008 struct event_trigger_data *trigger_data)
1009{
1010 char *number;
1011 int ret = 0;
1012
1013 if (param) {
1014 number = strsep(&param, ":");
1015
1016 if (!strlen(number))
1017 return -EINVAL;
1018
1019 /*
1020 * We use the callback data field (which is a pointer)
1021 * as our counter.
1022 */
1023 ret = kstrtoul(number, 0, &trigger_data->count);
1024 }
1025
1026 return ret;
1027}
1028
1029/**
1030 * event_trigger_set_filter - set an event trigger's filter
1031 * @cmd_ops: The event_command operations for the trigger
1032 * @file: The event file for the trigger's event
1033 * @param: The string containing the filter
1034 * @trigger_data: The trigger_data for the trigger
1035 *
1036 * Set the filter for the trigger. If the filter is NULL, just return
1037 * without error.
1038 *
1039 * Return: 0 on success, errno otherwise
1040 */
1041int event_trigger_set_filter(struct event_command *cmd_ops,
1042 struct trace_event_file *file,
1043 char *param,
1044 struct event_trigger_data *trigger_data)
1045{
1046 if (param && cmd_ops->set_filter)
1047 return cmd_ops->set_filter(param, trigger_data, file);
1048
1049 return 0;
1050}
1051
1052/**
1053 * event_trigger_reset_filter - reset an event trigger's filter
1054 * @cmd_ops: The event_command operations for the trigger
1055 * @trigger_data: The trigger_data for the trigger
1056 *
1057 * Reset the filter for the trigger to no filter.
1058 */
1059void event_trigger_reset_filter(struct event_command *cmd_ops,
1060 struct event_trigger_data *trigger_data)
1061{
1062 if (cmd_ops->set_filter)
1063 cmd_ops->set_filter(NULL, trigger_data, NULL);
1064}
1065
1066/**
1067 * event_trigger_register - register an event trigger
1068 * @cmd_ops: The event_command operations for the trigger
1069 * @file: The event file for the trigger's event
1070 * @glob: The trigger command string, with optional remove(!) operator
1071 * @trigger_data: The trigger_data for the trigger
1072 *
1073 * Register an event trigger. The @cmd_ops are used to call the
1074 * cmd_ops->reg() function which actually does the registration.
1075 *
1076 * Return: 0 on success, errno otherwise
1077 */
1078int event_trigger_register(struct event_command *cmd_ops,
1079 struct trace_event_file *file,
1080 char *glob,
1081 struct event_trigger_data *trigger_data)
1082{
1083 return cmd_ops->reg(glob, trigger_data, file);
1084}
1085
1086/**
1087 * event_trigger_unregister - unregister an event trigger
1088 * @cmd_ops: The event_command operations for the trigger
1089 * @file: The event file for the trigger's event
1090 * @glob: The trigger command string, with optional remove(!) operator
1091 * @trigger_data: The trigger_data for the trigger
1092 *
1093 * Unregister an event trigger. The @cmd_ops are used to call the
1094 * cmd_ops->unreg() function which actually does the unregistration.
1095 */
1096void event_trigger_unregister(struct event_command *cmd_ops,
1097 struct trace_event_file *file,
1098 char *glob,
1099 struct event_trigger_data *trigger_data)
1100{
1101 cmd_ops->unreg(glob, trigger_data, file);
1102}
1103
1104/*
1105 * End event trigger parsing helper functions.
1106 */
1107
1108/**
1109 * event_trigger_parse - Generic event_command @parse implementation
1110 * @cmd_ops: The command ops, used for trigger registration
1111 * @file: The trace_event_file associated with the event
1112 * @glob: The raw string used to register the trigger
1113 * @cmd: The cmd portion of the string used to register the trigger
1114 * @param_and_filter: The param and filter portion of the string used to register the trigger
1115 *
1116 * Common implementation for event command parsing and trigger
1117 * instantiation.
1118 *
1119 * Usually used directly as the @parse method in event command
1120 * implementations.
1121 *
1122 * Return: 0 on success, errno otherwise
1123 */
1124static int
1125event_trigger_parse(struct event_command *cmd_ops,
1126 struct trace_event_file *file,
1127 char *glob, char *cmd, char *param_and_filter)
1128{
1129 struct event_trigger_data *trigger_data;
1130 char *param, *filter;
1131 bool remove;
1132 int ret;
1133
1134 remove = event_trigger_check_remove(glob);
1135
1136 ret = event_trigger_separate_filter(param_and_filter, &param, &filter, false);
1137 if (ret)
1138 return ret;
1139
1140 ret = -ENOMEM;
1141 trigger_data = trigger_data_alloc(cmd_ops, cmd, param, file);
1142 if (!trigger_data)
1143 return ret;
1144
1145 if (remove) {
1146 event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
1147 trigger_data_free(trigger_data);
1148 return 0;
1149 }
1150
1151 ret = event_trigger_parse_num(param, trigger_data);
1152 if (ret)
1153 goto out_free;
1154
1155 ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
1156 if (ret < 0)
1157 goto out_free;
1158
1159 /* Up the trigger_data count to make sure reg doesn't free it on failure */
1160 event_trigger_init(trigger_data);
1161
1162 ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
1163 if (ret)
1164 goto out_free;
1165
1166 /* Down the counter of trigger_data or free it if not used anymore */
1167 event_trigger_free(trigger_data);
1168 return ret;
1169
1170 out_free:
1171 event_trigger_reset_filter(cmd_ops, trigger_data);
1172 trigger_data_free(trigger_data);
1173 return ret;
1174}
1175
1176/**
1177 * set_trigger_filter - Generic event_command @set_filter implementation
1178 * @filter_str: The filter string for the trigger, NULL to remove filter
1179 * @trigger_data: Trigger-specific data
1180 * @file: The trace_event_file associated with the event
1181 *
1182 * Common implementation for event command filter parsing and filter
1183 * instantiation.
1184 *
1185 * Usually used directly as the @set_filter method in event command
1186 * implementations.
1187 *
1188 * Also used to remove a filter (if filter_str = NULL).
1189 *
1190 * Return: 0 on success, errno otherwise
1191 */
1192int set_trigger_filter(char *filter_str,
1193 struct event_trigger_data *trigger_data,
1194 struct trace_event_file *file)
1195{
1196 struct event_trigger_data *data = trigger_data;
1197 struct event_filter *filter = NULL, *tmp;
1198 int ret = -EINVAL;
1199 char *s;
1200
1201 if (!filter_str) /* clear the current filter */
1202 goto assign;
1203
1204 s = strsep(&filter_str, " \t");
1205
1206 if (!strlen(s) || strcmp(s, "if") != 0)
1207 return ret;
1208
1209 if (!filter_str)
1210 return ret;
1211
1212 /* The filter is for the 'trigger' event, not the triggered event */
1213 ret = create_event_filter(file->tr, file->event_call,
1214 filter_str, true, &filter);
1215
1216 /* Only enabled set_str for error handling */
1217 if (filter) {
1218 kfree(filter->filter_string);
1219 filter->filter_string = NULL;
1220 }
1221
1222 /*
1223 * If create_event_filter() fails, filter still needs to be freed.
1224 * Which the calling code will do with data->filter.
1225 */
1226 assign:
1227 tmp = rcu_access_pointer(data->filter);
1228
1229 rcu_assign_pointer(data->filter, filter);
1230
1231 if (tmp) {
1232 /*
1233 * Make sure the call is done with the filter.
1234 * It is possible that a filter could fail at boot up,
1235 * and then this path will be called. Avoid the synchronization
1236 * in that case.
1237 */
1238 if (system_state != SYSTEM_BOOTING)
1239 tracepoint_synchronize_unregister();
1240 free_event_filter(tmp);
1241 }
1242
1243 kfree(data->filter_str);
1244 data->filter_str = NULL;
1245
1246 if (filter_str) {
1247 data->filter_str = kstrdup(filter_str, GFP_KERNEL);
1248 if (!data->filter_str) {
1249 free_event_filter(rcu_access_pointer(data->filter));
1250 data->filter = NULL;
1251 ret = -ENOMEM;
1252 }
1253 }
1254 return ret;
1255}
1256
1257static LIST_HEAD(named_triggers);
1258
1259/**
1260 * find_named_trigger - Find the common named trigger associated with @name
1261 * @name: The name of the set of named triggers to find the common data for
1262 *
1263 * Named triggers are sets of triggers that share a common set of
1264 * trigger data. The first named trigger registered with a given name
1265 * owns the common trigger data that the others subsequently
1266 * registered with the same name will reference. This function
1267 * returns the common trigger data associated with that first
1268 * registered instance.
1269 *
1270 * Return: the common trigger data for the given named trigger on
1271 * success, NULL otherwise.
1272 */
1273struct event_trigger_data *find_named_trigger(const char *name)
1274{
1275 struct event_trigger_data *data;
1276
1277 if (!name)
1278 return NULL;
1279
1280 list_for_each_entry(data, &named_triggers, named_list) {
1281 if (data->named_data)
1282 continue;
1283 if (strcmp(data->name, name) == 0)
1284 return data;
1285 }
1286
1287 return NULL;
1288}
1289
1290/**
1291 * is_named_trigger - determine if a given trigger is a named trigger
1292 * @test: The trigger data to test
1293 *
1294 * Return: true if 'test' is a named trigger, false otherwise.
1295 */
1296bool is_named_trigger(struct event_trigger_data *test)
1297{
1298 struct event_trigger_data *data;
1299
1300 list_for_each_entry(data, &named_triggers, named_list) {
1301 if (test == data)
1302 return true;
1303 }
1304
1305 return false;
1306}
1307
1308/**
1309 * save_named_trigger - save the trigger in the named trigger list
1310 * @name: The name of the named trigger set
1311 * @data: The trigger data to save
1312 *
1313 * Return: 0 if successful, negative error otherwise.
1314 */
1315int save_named_trigger(const char *name, struct event_trigger_data *data)
1316{
1317 data->name = kstrdup(name, GFP_KERNEL);
1318 if (!data->name)
1319 return -ENOMEM;
1320
1321 list_add(&data->named_list, &named_triggers);
1322
1323 return 0;
1324}
1325
1326/**
1327 * del_named_trigger - delete a trigger from the named trigger list
1328 * @data: The trigger data to delete
1329 */
1330void del_named_trigger(struct event_trigger_data *data)
1331{
1332 kfree(data->name);
1333 data->name = NULL;
1334
1335 list_del(&data->named_list);
1336}
1337
1338static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
1339{
1340 struct event_trigger_data *test;
1341
1342 list_for_each_entry(test, &named_triggers, named_list) {
1343 if (strcmp(test->name, data->name) == 0) {
1344 if (pause) {
1345 test->paused_tmp = test->paused;
1346 test->paused = true;
1347 } else {
1348 test->paused = test->paused_tmp;
1349 }
1350 }
1351 }
1352}
1353
1354/**
1355 * pause_named_trigger - Pause all named triggers with the same name
1356 * @data: The trigger data of a named trigger to pause
1357 *
1358 * Pauses a named trigger along with all other triggers having the
1359 * same name. Because named triggers share a common set of data,
1360 * pausing only one is meaningless, so pausing one named trigger needs
1361 * to pause all triggers with the same name.
1362 */
1363void pause_named_trigger(struct event_trigger_data *data)
1364{
1365 __pause_named_trigger(data, true);
1366}
1367
1368/**
1369 * unpause_named_trigger - Un-pause all named triggers with the same name
1370 * @data: The trigger data of a named trigger to unpause
1371 *
1372 * Un-pauses a named trigger along with all other triggers having the
1373 * same name. Because named triggers share a common set of data,
1374 * unpausing only one is meaningless, so unpausing one named trigger
1375 * needs to unpause all triggers with the same name.
1376 */
1377void unpause_named_trigger(struct event_trigger_data *data)
1378{
1379 __pause_named_trigger(data, false);
1380}
1381
1382/**
1383 * set_named_trigger_data - Associate common named trigger data
1384 * @data: The trigger data to associate
1385 * @named_data: The common named trigger to be associated
1386 *
1387 * Named triggers are sets of triggers that share a common set of
1388 * trigger data. The first named trigger registered with a given name
1389 * owns the common trigger data that the others subsequently
1390 * registered with the same name will reference. This function
1391 * associates the common trigger data from the first trigger with the
1392 * given trigger.
1393 */
1394void set_named_trigger_data(struct event_trigger_data *data,
1395 struct event_trigger_data *named_data)
1396{
1397 data->named_data = named_data;
1398}
1399
1400struct event_trigger_data *
1401get_named_trigger_data(struct event_trigger_data *data)
1402{
1403 return data->named_data;
1404}
1405
1406static void
1407traceon_trigger(struct event_trigger_data *data,
1408 struct trace_buffer *buffer, void *rec,
1409 struct ring_buffer_event *event)
1410{
1411 struct trace_event_file *file = data->private_data;
1412
1413 if (WARN_ON_ONCE(!file))
1414 return;
1415
1416 if (tracer_tracing_is_on(file->tr))
1417 return;
1418
1419 tracer_tracing_on(file->tr);
1420}
1421
1422static bool
1423traceon_count_func(struct event_trigger_data *data,
1424 struct trace_buffer *buffer, void *rec,
1425 struct ring_buffer_event *event)
1426{
1427 struct trace_event_file *file = data->private_data;
1428
1429 if (WARN_ON_ONCE(!file))
1430 return false;
1431
1432 if (tracer_tracing_is_on(file->tr))
1433 return false;
1434
1435 if (!data->count)
1436 return false;
1437
1438 if (data->count != -1)
1439 (data->count)--;
1440
1441 return true;
1442}
1443
1444static void
1445traceoff_trigger(struct event_trigger_data *data,
1446 struct trace_buffer *buffer, void *rec,
1447 struct ring_buffer_event *event)
1448{
1449 struct trace_event_file *file = data->private_data;
1450
1451 if (WARN_ON_ONCE(!file))
1452 return;
1453
1454 if (!tracer_tracing_is_on(file->tr))
1455 return;
1456
1457 tracer_tracing_off(file->tr);
1458}
1459
1460static bool
1461traceoff_count_func(struct event_trigger_data *data,
1462 struct trace_buffer *buffer, void *rec,
1463 struct ring_buffer_event *event)
1464{
1465 struct trace_event_file *file = data->private_data;
1466
1467 if (WARN_ON_ONCE(!file))
1468 return false;
1469
1470 if (!tracer_tracing_is_on(file->tr))
1471 return false;
1472
1473 if (!data->count)
1474 return false;
1475
1476 if (data->count != -1)
1477 (data->count)--;
1478
1479 return true;
1480}
1481
1482static int
1483traceon_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1484{
1485 return event_trigger_print("traceon", m, (void *)data->count,
1486 data->filter_str);
1487}
1488
1489static int
1490traceoff_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1491{
1492 return event_trigger_print("traceoff", m, (void *)data->count,
1493 data->filter_str);
1494}
1495
1496static struct event_command trigger_traceon_cmd = {
1497 .name = "traceon",
1498 .trigger_type = ETT_TRACE_ONOFF,
1499 .parse = event_trigger_parse,
1500 .reg = register_trigger,
1501 .unreg = unregister_trigger,
1502 .set_filter = set_trigger_filter,
1503 .trigger = traceon_trigger,
1504 .count_func = traceon_count_func,
1505 .print = traceon_trigger_print,
1506 .init = event_trigger_init,
1507 .free = event_trigger_free,
1508};
1509
1510static struct event_command trigger_traceoff_cmd = {
1511 .name = "traceoff",
1512 .trigger_type = ETT_TRACE_ONOFF,
1513 .flags = EVENT_CMD_FL_POST_TRIGGER,
1514 .parse = event_trigger_parse,
1515 .reg = register_trigger,
1516 .unreg = unregister_trigger,
1517 .set_filter = set_trigger_filter,
1518 .trigger = traceoff_trigger,
1519 .count_func = traceoff_count_func,
1520 .print = traceoff_trigger_print,
1521 .init = event_trigger_init,
1522 .free = event_trigger_free,
1523};
1524
1525#ifdef CONFIG_TRACER_SNAPSHOT
1526static void
1527snapshot_trigger(struct event_trigger_data *data,
1528 struct trace_buffer *buffer, void *rec,
1529 struct ring_buffer_event *event)
1530{
1531 struct trace_event_file *file = data->private_data;
1532
1533 if (WARN_ON_ONCE(!file))
1534 return;
1535
1536 tracing_snapshot_instance(file->tr);
1537}
1538
1539static int
1540register_snapshot_trigger(char *glob,
1541 struct event_trigger_data *data,
1542 struct trace_event_file *file)
1543{
1544 int ret = tracing_arm_snapshot(file->tr);
1545
1546 if (ret < 0)
1547 return ret;
1548
1549 ret = register_trigger(glob, data, file);
1550 if (ret < 0)
1551 tracing_disarm_snapshot(file->tr);
1552 return ret;
1553}
1554
1555static void unregister_snapshot_trigger(char *glob,
1556 struct event_trigger_data *data,
1557 struct trace_event_file *file)
1558{
1559 if (try_unregister_trigger(glob, data, file))
1560 tracing_disarm_snapshot(file->tr);
1561}
1562
1563static int
1564snapshot_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1565{
1566 return event_trigger_print("snapshot", m, (void *)data->count,
1567 data->filter_str);
1568}
1569
1570static struct event_command trigger_snapshot_cmd = {
1571 .name = "snapshot",
1572 .trigger_type = ETT_SNAPSHOT,
1573 .parse = event_trigger_parse,
1574 .reg = register_snapshot_trigger,
1575 .unreg = unregister_snapshot_trigger,
1576 .set_filter = set_trigger_filter,
1577 .trigger = snapshot_trigger,
1578 .count_func = event_trigger_count,
1579 .print = snapshot_trigger_print,
1580 .init = event_trigger_init,
1581 .free = event_trigger_free,
1582};
1583
1584static __init int register_trigger_snapshot_cmd(void)
1585{
1586 int ret;
1587
1588 ret = register_event_command(&trigger_snapshot_cmd);
1589 WARN_ON(ret < 0);
1590
1591 return ret;
1592}
1593#else
1594static __init int register_trigger_snapshot_cmd(void) { return 0; }
1595#endif /* CONFIG_TRACER_SNAPSHOT */
1596
1597#ifdef CONFIG_STACKTRACE
1598#ifdef CONFIG_UNWINDER_ORC
1599/* Skip 2:
1600 * event_triggers_post_call()
1601 * trace_event_raw_event_xxx()
1602 */
1603# define STACK_SKIP 2
1604#else
1605/*
1606 * Skip 4:
1607 * stacktrace_trigger()
1608 * event_triggers_post_call()
1609 * trace_event_buffer_commit()
1610 * trace_event_raw_event_xxx()
1611 */
1612#define STACK_SKIP 4
1613#endif
1614
1615static void
1616stacktrace_trigger(struct event_trigger_data *data,
1617 struct trace_buffer *buffer, void *rec,
1618 struct ring_buffer_event *event)
1619{
1620 struct trace_event_file *file = data->private_data;
1621
1622 if (WARN_ON_ONCE(!file))
1623 return;
1624
1625 __trace_stack(file->tr, tracing_gen_ctx_dec(), STACK_SKIP);
1626}
1627
1628static int
1629stacktrace_trigger_print(struct seq_file *m, struct event_trigger_data *data)
1630{
1631 return event_trigger_print("stacktrace", m, (void *)data->count,
1632 data->filter_str);
1633}
1634
1635static struct event_command trigger_stacktrace_cmd = {
1636 .name = "stacktrace",
1637 .trigger_type = ETT_STACKTRACE,
1638 .flags = EVENT_CMD_FL_POST_TRIGGER,
1639 .parse = event_trigger_parse,
1640 .reg = register_trigger,
1641 .unreg = unregister_trigger,
1642 .set_filter = set_trigger_filter,
1643 .trigger = stacktrace_trigger,
1644 .count_func = event_trigger_count,
1645 .print = stacktrace_trigger_print,
1646 .init = event_trigger_init,
1647 .free = event_trigger_free,
1648};
1649
1650static __init int register_trigger_stacktrace_cmd(void)
1651{
1652 int ret;
1653
1654 ret = register_event_command(&trigger_stacktrace_cmd);
1655 WARN_ON(ret < 0);
1656
1657 return ret;
1658}
1659#else
1660static __init int register_trigger_stacktrace_cmd(void) { return 0; }
1661#endif /* CONFIG_STACKTRACE */
1662
1663static __init void unregister_trigger_traceon_traceoff_cmds(void)
1664{
1665 unregister_event_command(&trigger_traceon_cmd);
1666 unregister_event_command(&trigger_traceoff_cmd);
1667}
1668
1669static void
1670event_enable_trigger(struct event_trigger_data *data,
1671 struct trace_buffer *buffer, void *rec,
1672 struct ring_buffer_event *event)
1673{
1674 struct enable_trigger_data *enable_data = data->private_data;
1675
1676 if (enable_data->enable)
1677 clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1678 else
1679 set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
1680}
1681
1682static bool
1683event_enable_count_func(struct event_trigger_data *data,
1684 struct trace_buffer *buffer, void *rec,
1685 struct ring_buffer_event *event)
1686{
1687 struct enable_trigger_data *enable_data = data->private_data;
1688
1689 if (!data->count)
1690 return false;
1691
1692 /* Skip if the event is in a state we want to switch to */
1693 if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
1694 return false;
1695
1696 if (data->count != -1)
1697 (data->count)--;
1698
1699 return true;
1700}
1701
1702int event_enable_trigger_print(struct seq_file *m,
1703 struct event_trigger_data *data)
1704{
1705 struct enable_trigger_data *enable_data = data->private_data;
1706
1707 seq_printf(m, "%s:%s:%s",
1708 enable_data->hist ?
1709 (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
1710 (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
1711 enable_data->file->event_call->class->system,
1712 trace_event_name(enable_data->file->event_call));
1713
1714 if (data->count == -1)
1715 seq_puts(m, ":unlimited");
1716 else
1717 seq_printf(m, ":count=%ld", data->count);
1718
1719 if (data->filter_str)
1720 seq_printf(m, " if %s\n", data->filter_str);
1721 else
1722 seq_putc(m, '\n');
1723
1724 return 0;
1725}
1726
1727static void enable_trigger_private_data_free(struct event_trigger_data *data)
1728{
1729 struct enable_trigger_data *enable_data = data->private_data;
1730
1731 /* The file may already be freed here, only the call is kept alive */
1732 trace_event_put_ref(enable_data->call);
1733 kfree(enable_data);
1734}
1735
1736void event_enable_trigger_free(struct event_trigger_data *data)
1737{
1738 struct enable_trigger_data *enable_data = data->private_data;
1739
1740 if (WARN_ON_ONCE(data->ref <= 0))
1741 return;
1742
1743 data->ref--;
1744 if (!data->ref) {
1745 /* Remove the SOFT_MODE flag */
1746 trace_event_enable_disable(enable_data->file, 0, 1);
1747 data->private_data_free = enable_trigger_private_data_free;
1748 trigger_data_free(data);
1749 }
1750}
1751
1752int event_enable_trigger_parse(struct event_command *cmd_ops,
1753 struct trace_event_file *file,
1754 char *glob, char *cmd, char *param_and_filter)
1755{
1756 struct trace_event_file *event_enable_file;
1757 struct enable_trigger_data *enable_data __free(kfree) = NULL;
1758 struct event_trigger_data *trigger_data;
1759 struct trace_array *tr = file->tr;
1760 char *param, *filter;
1761 bool enable, remove;
1762 const char *system;
1763 const char *event;
1764 bool hist = false;
1765 int ret;
1766
1767 remove = event_trigger_check_remove(glob);
1768
1769 if (event_trigger_empty_param(param_and_filter))
1770 return -EINVAL;
1771
1772 ret = event_trigger_separate_filter(param_and_filter, &param, &filter, true);
1773 if (ret)
1774 return ret;
1775
1776 system = strsep(&param, ":");
1777 if (!param)
1778 return -EINVAL;
1779
1780 event = strsep(&param, ":");
1781
1782 ret = -EINVAL;
1783 event_enable_file = find_event_file(tr, system, event);
1784 if (!event_enable_file)
1785 return ret;
1786
1787#ifdef CONFIG_HIST_TRIGGERS
1788 hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
1789 (strcmp(cmd, DISABLE_HIST_STR) == 0));
1790
1791 enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
1792 (strcmp(cmd, ENABLE_HIST_STR) == 0));
1793#else
1794 enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
1795#endif
1796 ret = -ENOMEM;
1797
1798 enable_data = kzalloc_obj(*enable_data);
1799 if (!enable_data)
1800 return ret;
1801
1802 enable_data->hist = hist;
1803 enable_data->enable = enable;
1804 enable_data->file = event_enable_file;
1805 enable_data->call = event_enable_file->event_call;
1806
1807 trigger_data = trigger_data_alloc(cmd_ops, cmd, param, enable_data);
1808 if (!trigger_data)
1809 return ret;
1810
1811 if (remove) {
1812 event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
1813 kfree(trigger_data);
1814 return 0;
1815 }
1816
1817 /* Up the trigger_data count to make sure nothing frees it on failure */
1818 event_trigger_init(trigger_data);
1819
1820 ret = event_trigger_parse_num(param, trigger_data);
1821 if (ret)
1822 goto out_free;
1823
1824 ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
1825 if (ret < 0)
1826 goto out_free;
1827
1828 /* Don't let event modules unload while probe registered */
1829 ret = trace_event_try_get_ref(event_enable_file->event_call);
1830 if (!ret) {
1831 ret = -EBUSY;
1832 goto out_free;
1833 }
1834
1835 ret = trace_event_enable_disable(event_enable_file, 1, 1);
1836 if (ret < 0)
1837 goto out_put;
1838
1839 ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
1840 if (ret)
1841 goto out_disable;
1842
1843 /* It's now safe to free the reference taken earlier */
1844 event_trigger_free(trigger_data);
1845
1846 /* The enabled_data is assigned to trigger_data->private_data */
1847 retain_and_null_ptr(enable_data);
1848
1849 return ret;
1850 out_disable:
1851 trace_event_enable_disable(event_enable_file, 0, 1);
1852 out_put:
1853 trace_event_put_ref(event_enable_file->event_call);
1854 out_free:
1855 event_trigger_reset_filter(cmd_ops, trigger_data);
1856 event_trigger_free(trigger_data);
1857
1858 return ret;
1859}
1860
1861int event_enable_register_trigger(char *glob,
1862 struct event_trigger_data *data,
1863 struct trace_event_file *file)
1864{
1865 struct enable_trigger_data *enable_data = data->private_data;
1866 struct enable_trigger_data *test_enable_data;
1867 struct event_trigger_data *test;
1868 int ret = 0;
1869
1870 lockdep_assert_held(&event_mutex);
1871
1872 list_for_each_entry(test, &file->triggers, list) {
1873 test_enable_data = test->private_data;
1874 if (test_enable_data &&
1875 (test->cmd_ops->trigger_type ==
1876 data->cmd_ops->trigger_type) &&
1877 (test_enable_data->file == enable_data->file)) {
1878 return -EEXIST;
1879 }
1880 }
1881
1882 if (data->cmd_ops->init) {
1883 ret = data->cmd_ops->init(data);
1884 if (ret < 0)
1885 return ret;
1886 }
1887
1888 list_add_rcu(&data->list, &file->triggers);
1889
1890 update_cond_flag(file);
1891 ret = trace_event_trigger_enable_disable(file, 1);
1892 if (ret < 0) {
1893 list_del_rcu(&data->list);
1894 update_cond_flag(file);
1895 }
1896 return ret;
1897}
1898
1899void event_enable_unregister_trigger(char *glob,
1900 struct event_trigger_data *test,
1901 struct trace_event_file *file)
1902{
1903 struct enable_trigger_data *test_enable_data = test->private_data;
1904 struct event_trigger_data *data = NULL, *iter;
1905 struct enable_trigger_data *enable_data;
1906
1907 lockdep_assert_held(&event_mutex);
1908
1909 list_for_each_entry(iter, &file->triggers, list) {
1910 enable_data = iter->private_data;
1911 if (enable_data &&
1912 (iter->cmd_ops->trigger_type ==
1913 test->cmd_ops->trigger_type) &&
1914 (enable_data->file == test_enable_data->file)) {
1915 data = iter;
1916 list_del_rcu(&data->list);
1917 trace_event_trigger_enable_disable(file, 0);
1918 update_cond_flag(file);
1919 break;
1920 }
1921 }
1922
1923 if (data && data->cmd_ops->free)
1924 data->cmd_ops->free(data);
1925}
1926
1927static struct event_command trigger_enable_cmd = {
1928 .name = ENABLE_EVENT_STR,
1929 .trigger_type = ETT_EVENT_ENABLE,
1930 .parse = event_enable_trigger_parse,
1931 .reg = event_enable_register_trigger,
1932 .unreg = event_enable_unregister_trigger,
1933 .set_filter = set_trigger_filter,
1934 .trigger = event_enable_trigger,
1935 .count_func = event_enable_count_func,
1936 .print = event_enable_trigger_print,
1937 .init = event_trigger_init,
1938 .free = event_enable_trigger_free,
1939};
1940
1941static struct event_command trigger_disable_cmd = {
1942 .name = DISABLE_EVENT_STR,
1943 .trigger_type = ETT_EVENT_ENABLE,
1944 .parse = event_enable_trigger_parse,
1945 .reg = event_enable_register_trigger,
1946 .unreg = event_enable_unregister_trigger,
1947 .set_filter = set_trigger_filter,
1948 .trigger = event_enable_trigger,
1949 .count_func = event_enable_count_func,
1950 .print = event_enable_trigger_print,
1951 .init = event_trigger_init,
1952 .free = event_enable_trigger_free,
1953};
1954
1955static __init void unregister_trigger_enable_disable_cmds(void)
1956{
1957 unregister_event_command(&trigger_enable_cmd);
1958 unregister_event_command(&trigger_disable_cmd);
1959}
1960
1961static __init int register_trigger_enable_disable_cmds(void)
1962{
1963 int ret;
1964
1965 ret = register_event_command(&trigger_enable_cmd);
1966 if (WARN_ON(ret < 0))
1967 return ret;
1968 ret = register_event_command(&trigger_disable_cmd);
1969 if (WARN_ON(ret < 0))
1970 unregister_trigger_enable_disable_cmds();
1971
1972 return ret;
1973}
1974
1975static __init int register_trigger_traceon_traceoff_cmds(void)
1976{
1977 int ret;
1978
1979 ret = register_event_command(&trigger_traceon_cmd);
1980 if (WARN_ON(ret < 0))
1981 return ret;
1982 ret = register_event_command(&trigger_traceoff_cmd);
1983 if (WARN_ON(ret < 0))
1984 unregister_trigger_traceon_traceoff_cmds();
1985
1986 return ret;
1987}
1988
1989__init int register_trigger_cmds(void)
1990{
1991 register_trigger_traceon_traceoff_cmds();
1992 register_trigger_snapshot_cmd();
1993 register_trigger_stacktrace_cmd();
1994 register_trigger_enable_disable_cmds();
1995 register_trigger_hist_enable_disable_cmds();
1996 register_trigger_hist_cmd();
1997
1998 return 0;
1999}