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