summaryrefslogtreecommitdiff
path: root/include/linux/ftrace_event.h
blob: d16da3e53bc732710e7ea05e3e500d0f1784a94c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
#ifndef _LINUX_FTRACE_EVENT_H
#define _LINUX_FTRACE_EVENT_H

#include <linux/ring_buffer.h>
#include <linux/trace_seq.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/perf_event.h>
#include <linux/tracepoint.h>

struct trace_array;
struct trace_buffer;
struct tracer;
struct dentry;

struct trace_print_flags {
	unsigned long		mask;
	const char		*name;
};

struct trace_print_flags_u64 {
	unsigned long long	mask;
	const char		*name;
};

const char *ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
				   unsigned long flags,
				   const struct trace_print_flags *flag_array);

const char *ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
				     const struct trace_print_flags *symbol_array);

#if BITS_PER_LONG == 32
const char *ftrace_print_symbols_seq_u64(struct trace_seq *p,
					 unsigned long long val,
					 const struct trace_print_flags_u64
								 *symbol_array);
#endif

const char *ftrace_print_hex_seq(struct trace_seq *p,
				 const unsigned char *buf, int len);

struct trace_iterator;
struct trace_event;

int ftrace_raw_output_prep(struct trace_iterator *iter,
			   struct trace_event *event);

/*
 * The trace entry - the most basic unit of tracing. This is what
 * is printed in the end as a single line in the trace output, such as:
 *
 *     bash-15816 [01]   235.197585: idle_cpu <- irq_enter
 */
struct trace_entry {
	unsigned short		type;
	unsigned char		flags;
	unsigned char		preempt_count;
	int			pid;
};

#define FTRACE_MAX_EVENT						\
	((1 << (sizeof(((struct trace_entry *)0)->type) * 8)) - 1)

/*
 * Trace iterator - used by printout routines who present trace
 * results to users and which routines might sleep, etc:
 */
struct trace_iterator {
	struct trace_array	*tr;
	struct tracer		*trace;
	struct trace_buffer	*trace_buffer;
	void			*private;
	int			cpu_file;
	struct mutex		mutex;
	struct ring_buffer_iter	**buffer_iter;
	unsigned long		iter_flags;

	/* trace_seq for __print_flags() and __print_symbolic() etc. */
	struct trace_seq	tmp_seq;

	cpumask_var_t		started;

	/* it's true when current open file is snapshot */
	bool			snapshot;

	/* The below is zeroed out in pipe_read */
	struct trace_seq	seq;
	struct trace_entry	*ent;
	unsigned long		lost_events;
	int			leftover;
	int			ent_size;
	int			cpu;
	u64			ts;

	loff_t			pos;
	long			idx;

	/* All new field here will be zeroed out in pipe_read */
};

enum trace_iter_flags {
	TRACE_FILE_LAT_FMT	= 1,
	TRACE_FILE_ANNOTATE	= 2,
	TRACE_FILE_TIME_IN_NS	= 4,
};


typedef enum print_line_t (*trace_print_func)(struct trace_iterator *iter,
				      int flags, struct trace_event *event);

struct trace_event_functions {
	trace_print_func	trace;
	trace_print_func	raw;
	trace_print_func	hex;
	trace_print_func	binary;
};

struct trace_event {
	struct hlist_node		node;
	struct list_head		list;
	int				type;
	struct trace_event_functions	*funcs;
};

extern int register_ftrace_event(struct trace_event *event);
extern int unregister_ftrace_event(struct trace_event *event);

/* Return values for print_line callback */
enum print_line_t {
	TRACE_TYPE_PARTIAL_LINE	= 0,	/* Retry after flushing the seq */
	TRACE_TYPE_HANDLED	= 1,
	TRACE_TYPE_UNHANDLED	= 2,	/* Relay to other output functions */
	TRACE_TYPE_NO_CONSUME	= 3	/* Handled but ask to not consume */
};

void tracing_generic_entry_update(struct trace_entry *entry,
				  unsigned long flags,
				  int pc);
struct ftrace_event_file;

struct ring_buffer_event *
trace_event_buffer_lock_reserve(struct ring_buffer **current_buffer,
				struct ftrace_event_file *ftrace_file,
				int type, unsigned long len,
				unsigned long flags, int pc);
struct ring_buffer_event *
trace_current_buffer_lock_reserve(struct ring_buffer **current_buffer,
				  int type, unsigned long len,
				  unsigned long flags, int pc);
void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
					struct ring_buffer_event *event,
					unsigned long flags, int pc);
void trace_buffer_unlock_commit(struct ring_buffer *buffer,
				struct ring_buffer_event *event,
				unsigned long flags, int pc);
void trace_buffer_unlock_commit_regs(struct ring_buffer *buffer,
				     struct ring_buffer_event *event,
				     unsigned long flags, int pc,
				     struct pt_regs *regs);
void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
					 struct ring_buffer_event *event);

void tracing_record_cmdline(struct task_struct *tsk);

int ftrace_output_call(struct trace_iterator *iter, char *name, char *fmt, ...);

struct event_filter;

enum trace_reg {
	TRACE_REG_REGISTER,
	TRACE_REG_UNREGISTER,
#ifdef CONFIG_PERF_EVENTS
	TRACE_REG_PERF_REGISTER,
	TRACE_REG_PERF_UNREGISTER,
	TRACE_REG_PERF_OPEN,
	TRACE_REG_PERF_CLOSE,
	TRACE_REG_PERF_ADD,
	TRACE_REG_PERF_DEL,
#endif
};

struct ftrace_event_call;

struct ftrace_event_class {
	char			*system;
	void			*probe;
#ifdef CONFIG_PERF_EVENTS
	void			*perf_probe;
#endif
	int			(*reg)(struct ftrace_event_call *event,
				       enum trace_reg type, void *data);
	int			(*define_fields)(struct ftrace_event_call *);
	struct list_head	*(*get_fields)(struct ftrace_event_call *);
	struct list_head	fields;
	int			(*raw_init)(struct ftrace_event_call *);
};

extern int ftrace_event_reg(struct ftrace_event_call *event,
			    enum trace_reg type, void *data);

int ftrace_output_event(struct trace_iterator *iter, struct ftrace_event_call *event,
			char *fmt, ...);

int ftrace_event_define_field(struct ftrace_event_call *call,
			      char *type, int len, char *item, int offset,
			      int field_size, int sign, int filter);

struct ftrace_event_buffer {
	struct ring_buffer		*buffer;
	struct ring_buffer_event	*event;
	struct ftrace_event_file	*ftrace_file;
	void				*entry;
	unsigned long			flags;
	int				pc;
};

void *ftrace_event_buffer_reserve(struct ftrace_event_buffer *fbuffer,
				  struct ftrace_event_file *ftrace_file,
				  unsigned long len);

void ftrace_event_buffer_commit(struct ftrace_event_buffer *fbuffer);

int ftrace_event_define_field(struct ftrace_event_call *call,
			      char *type, int len, char *item, int offset,
			      int field_size, int sign, int filter);

enum {
	TRACE_EVENT_FL_FILTERED_BIT,
	TRACE_EVENT_FL_CAP_ANY_BIT,
	TRACE_EVENT_FL_NO_SET_FILTER_BIT,
	TRACE_EVENT_FL_IGNORE_ENABLE_BIT,
	TRACE_EVENT_FL_WAS_ENABLED_BIT,
	TRACE_EVENT_FL_USE_CALL_FILTER_BIT,
	TRACE_EVENT_FL_TRACEPOINT_BIT,
};

/*
 * Event flags:
 *  FILTERED	  - The event has a filter attached
 *  CAP_ANY	  - Any user can enable for perf
 *  NO_SET_FILTER - Set when filter has error and is to be ignored
 *  IGNORE_ENABLE - For ftrace internal events, do not enable with debugfs file
 *  WAS_ENABLED   - Set and stays set when an event was ever enabled
 *                    (used for module unloading, if a module event is enabled,
 *                     it is best to clear the buffers that used it).
 *  USE_CALL_FILTER - For ftrace internal events, don't use file filter
 *  TRACEPOINT    - Event is a tracepoint
 */
enum {
	TRACE_EVENT_FL_FILTERED		= (1 << TRACE_EVENT_FL_FILTERED_BIT),
	TRACE_EVENT_FL_CAP_ANY		= (1 << TRACE_EVENT_FL_CAP_ANY_BIT),
	TRACE_EVENT_FL_NO_SET_FILTER	= (1 << TRACE_EVENT_FL_NO_SET_FILTER_BIT),
	TRACE_EVENT_FL_IGNORE_ENABLE	= (1 << TRACE_EVENT_FL_IGNORE_ENABLE_BIT),
	TRACE_EVENT_FL_WAS_ENABLED	= (1 << TRACE_EVENT_FL_WAS_ENABLED_BIT),
	TRACE_EVENT_FL_USE_CALL_FILTER	= (1 << TRACE_EVENT_FL_USE_CALL_FILTER_BIT),
	TRACE_EVENT_FL_TRACEPOINT	= (1 << TRACE_EVENT_FL_TRACEPOINT_BIT),
};

struct ftrace_event_call {
	struct list_head	list;
	struct ftrace_event_class *class;
	union {
		char			*name;
		/* Set TRACE_EVENT_FL_TRACEPOINT flag when using "tp" */
		struct tracepoint	*tp;
	};
	struct trace_event	event;
	const char		*print_fmt;
	struct event_filter	*filter;
	struct list_head	*files;
	void			*mod;
	void			*data;
	/*
	 *   bit 0:		filter_active
	 *   bit 1:		allow trace by non root (cap any)
	 *   bit 2:		failed to apply filter
	 *   bit 3:		ftrace internal event (do not enable)
	 *   bit 4:		Event was enabled by module
	 *   bit 5:		use call filter rather than file filter
	 *   bit 6:		Event is a tracepoint
	 */
	int			flags; /* static flags of different events */

#ifdef CONFIG_PERF_EVENTS
	int				perf_refcount;
	struct hlist_head __percpu	*perf_events;

	int	(*perf_perm)(struct ftrace_event_call *,
			     struct perf_event *);
#endif
};

static inline const char *
ftrace_event_name(struct ftrace_event_call *call)
{
	if (call->flags & TRACE_EVENT_FL_TRACEPOINT)
		return call->tp ? call->tp->name : NULL;
	else
		return call->name;
}

struct trace_array;
struct ftrace_subsystem_dir;

enum {
	FTRACE_EVENT_FL_ENABLED_BIT,
	FTRACE_EVENT_FL_RECORDED_CMD_BIT,
	FTRACE_EVENT_FL_FILTERED_BIT,
	FTRACE_EVENT_FL_NO_SET_FILTER_BIT,
	FTRACE_EVENT_FL_SOFT_MODE_BIT,
	FTRACE_EVENT_FL_SOFT_DISABLED_BIT,
	FTRACE_EVENT_FL_TRIGGER_MODE_BIT,
	FTRACE_EVENT_FL_TRIGGER_COND_BIT,
};

/*
 * Ftrace event file flags:
 *  ENABLED	  - The event is enabled
 *  RECORDED_CMD  - The comms should be recorded at sched_switch
 *  FILTERED	  - The event has a filter attached
 *  NO_SET_FILTER - Set when filter has error and is to be ignored
 *  SOFT_MODE     - The event is enabled/disabled by SOFT_DISABLED
 *  SOFT_DISABLED - When set, do not trace the event (even though its
 *                   tracepoint may be enabled)
 *  TRIGGER_MODE  - When set, invoke the triggers associated with the event
 *  TRIGGER_COND  - When set, one or more triggers has an associated filter
 */
enum {
	FTRACE_EVENT_FL_ENABLED		= (1 << FTRACE_EVENT_FL_ENABLED_BIT),
	FTRACE_EVENT_FL_RECORDED_CMD	= (1 << FTRACE_EVENT_FL_RECORDED_CMD_BIT),
	FTRACE_EVENT_FL_FILTERED	= (1 << FTRACE_EVENT_FL_FILTERED_BIT),
	FTRACE_EVENT_FL_NO_SET_FILTER	= (1 << FTRACE_EVENT_FL_NO_SET_FILTER_BIT),
	FTRACE_EVENT_FL_SOFT_MODE	= (1 << FTRACE_EVENT_FL_SOFT_MODE_BIT),
	FTRACE_EVENT_FL_SOFT_DISABLED	= (1 << FTRACE_EVENT_FL_SOFT_DISABLED_BIT),
	FTRACE_EVENT_FL_TRIGGER_MODE	= (1 << FTRACE_EVENT_FL_TRIGGER_MODE_BIT),
	FTRACE_EVENT_FL_TRIGGER_COND	= (1 << FTRACE_EVENT_FL_TRIGGER_COND_BIT),
};

struct ftrace_event_file {
	struct list_head		list;
	struct ftrace_event_call	*event_call;
	struct event_filter		*filter;
	struct dentry			*dir;
	struct trace_array		*tr;
	struct ftrace_subsystem_dir	*system;
	struct list_head		triggers;

	/*
	 * 32 bit flags:
	 *   bit 0:		enabled
	 *   bit 1:		enabled cmd record
	 *   bit 2:		enable/disable with the soft disable bit
	 *   bit 3:		soft disabled
	 *   bit 4:		trigger enabled
	 *
	 * Note: The bits must be set atomically to prevent races
	 * from other writers. Reads of flags do not need to be in
	 * sync as they occur in critical sections. But the way flags
	 * is currently used, these changes do not affect the code
	 * except that when a change is made, it may have a slight
	 * delay in propagating the changes to other CPUs due to
	 * caching and such. Which is mostly OK ;-)
	 */
	unsigned long		flags;
	atomic_t		sm_ref;	/* soft-mode reference counter */
	atomic_t		tm_ref;	/* trigger-mode reference counter */
};

#define __TRACE_EVENT_FLAGS(name, value)				\
	static int __init trace_init_flags_##name(void)			\
	{								\
		event_##name.flags |= value;				\
		return 0;						\
	}								\
	early_initcall(trace_init_flags_##name);

#define __TRACE_EVENT_PERF_PERM(name, expr...)				\
	static int perf_perm_##name(struct ftrace_event_call *tp_event, \
				    struct perf_event *p_event)		\
	{								\
		return ({ expr; });					\
	}								\
	static int __init trace_init_perf_perm_##name(void)		\
	{								\
		event_##name.perf_perm = &perf_perm_##name;		\
		return 0;						\
	}								\
	early_initcall(trace_init_perf_perm_##name);

#define PERF_MAX_TRACE_SIZE	2048

#define MAX_FILTER_STR_VAL	256	/* Should handle KSYM_SYMBOL_LEN */

enum event_trigger_type {
	ETT_NONE		= (0),
	ETT_TRACE_ONOFF		= (1 << 0),
	ETT_SNAPSHOT		= (1 << 1),
	ETT_STACKTRACE		= (1 << 2),
	ETT_EVENT_ENABLE	= (1 << 3),
};

extern void destroy_preds(struct ftrace_event_file *file);
extern void destroy_call_preds(struct ftrace_event_call *call);
extern int filter_match_preds(struct event_filter *filter, void *rec);

extern int filter_check_discard(struct ftrace_event_file *file, void *rec,
				struct ring_buffer *buffer,
				struct ring_buffer_event *event);
extern int call_filter_check_discard(struct ftrace_event_call *call, void *rec,
				     struct ring_buffer *buffer,
				     struct ring_buffer_event *event);
extern enum event_trigger_type event_triggers_call(struct ftrace_event_file *file,
						   void *rec);
extern void event_triggers_post_call(struct ftrace_event_file *file,
				     enum event_trigger_type tt);

/**
 * ftrace_trigger_soft_disabled - do triggers and test if soft disabled
 * @file: The file pointer of the event to test
 *
 * If any triggers without filters are attached to this event, they
 * will be called here. If the event is soft disabled and has no
 * triggers that require testing the fields, it will return true,
 * otherwise false.
 */
static inline bool
ftrace_trigger_soft_disabled(struct ftrace_event_file *file)
{
	unsigned long eflags = file->flags;

	if (!(eflags & FTRACE_EVENT_FL_TRIGGER_COND)) {
		if (eflags & FTRACE_EVENT_FL_TRIGGER_MODE)
			event_triggers_call(file, NULL);
		if (eflags & FTRACE_EVENT_FL_SOFT_DISABLED)
			return true;
	}
	return false;
}

/*
 * Helper function for event_trigger_unlock_commit{_regs}().
 * If there are event triggers attached to this event that requires
 * filtering against its fields, then they wil be called as the
 * entry already holds the field information of the current event.
 *
 * It also checks if the event should be discarded or not.
 * It is to be discarded if the event is soft disabled and the
 * event was only recorded to process triggers, or if the event
 * filter is active and this event did not match the filters.
 *
 * Returns true if the event is discarded, false otherwise.
 */
static inline bool
__event_trigger_test_discard(struct ftrace_event_file *file,
			     struct ring_buffer *buffer,
			     struct ring_buffer_event *event,
			     void *entry,
			     enum event_trigger_type *tt)
{
	unsigned long eflags = file->flags;

	if (eflags & FTRACE_EVENT_FL_TRIGGER_COND)
		*tt = event_triggers_call(file, entry);

	if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags))
		ring_buffer_discard_commit(buffer, event);
	else if (!filter_check_discard(file, entry, buffer, event))
		return false;

	return true;
}

/**
 * event_trigger_unlock_commit - handle triggers and finish event commit
 * @file: The file pointer assoctiated to the event
 * @buffer: The ring buffer that the event is being written to
 * @event: The event meta data in the ring buffer
 * @entry: The event itself
 * @irq_flags: The state of the interrupts at the start of the event
 * @pc: The state of the preempt count at the start of the event.
 *
 * This is a helper function to handle triggers that require data
 * from the event itself. It also tests the event against filters and
 * if the event is soft disabled and should be discarded.
 */
static inline void
event_trigger_unlock_commit(struct ftrace_event_file *file,
			    struct ring_buffer *buffer,
			    struct ring_buffer_event *event,
			    void *entry, unsigned long irq_flags, int pc)
{
	enum event_trigger_type tt = ETT_NONE;

	if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
		trace_buffer_unlock_commit(buffer, event, irq_flags, pc);

	if (tt)
		event_triggers_post_call(file, tt);
}

/**
 * event_trigger_unlock_commit_regs - handle triggers and finish event commit
 * @file: The file pointer assoctiated to the event
 * @buffer: The ring buffer that the event is being written to
 * @event: The event meta data in the ring buffer
 * @entry: The event itself
 * @irq_flags: The state of the interrupts at the start of the event
 * @pc: The state of the preempt count at the start of the event.
 *
 * This is a helper function to handle triggers that require data
 * from the event itself. It also tests the event against filters and
 * if the event is soft disabled and should be discarded.
 *
 * Same as event_trigger_unlock_commit() but calls
 * trace_buffer_unlock_commit_regs() instead of trace_buffer_unlock_commit().
 */
static inline void
event_trigger_unlock_commit_regs(struct ftrace_event_file *file,
				 struct ring_buffer *buffer,
				 struct ring_buffer_event *event,
				 void *entry, unsigned long irq_flags, int pc,
				 struct pt_regs *regs)
{
	enum event_trigger_type tt = ETT_NONE;

	if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
		trace_buffer_unlock_commit_regs(buffer, event,
						irq_flags, pc, regs);

	if (tt)
		event_triggers_post_call(file, tt);
}

enum {
	FILTER_OTHER = 0,
	FILTER_STATIC_STRING,
	FILTER_DYN_STRING,
	FILTER_PTR_STRING,
	FILTER_TRACE_FN,
};

extern int trace_event_raw_init(struct ftrace_event_call *call);
extern int trace_define_field(struct ftrace_event_call *call, const char *type,
			      const char *name, int offset, int size,
			      int is_signed, int filter_type);
extern int trace_add_event_call(struct ftrace_event_call *call);
extern int trace_remove_event_call(struct ftrace_event_call *call);

#define is_signed_type(type)	(((type)(-1)) < (type)1)

int trace_set_clr_event(const char *system, const char *event, int set);

/*
 * The double __builtin_constant_p is because gcc will give us an error
 * if we try to allocate the static variable to fmt if it is not a
 * constant. Even with the outer if statement optimizing out.
 */
#define event_trace_printk(ip, fmt, args...)				\
do {									\
	__trace_printk_check_format(fmt, ##args);			\
	tracing_record_cmdline(current);				\
	if (__builtin_constant_p(fmt)) {				\
		static const char *trace_printk_fmt			\
		  __attribute__((section("__trace_printk_fmt"))) =	\
			__builtin_constant_p(fmt) ? fmt : NULL;		\
									\
		__trace_bprintk(ip, trace_printk_fmt, ##args);		\
	} else								\
		__trace_printk(ip, fmt, ##args);			\
} while (0)

/**
 * tracepoint_string - register constant persistent string to trace system
 * @str - a constant persistent string that will be referenced in tracepoints
 *
 * If constant strings are being used in tracepoints, it is faster and
 * more efficient to just save the pointer to the string and reference
 * that with a printf "%s" instead of saving the string in the ring buffer
 * and wasting space and time.
 *
 * The problem with the above approach is that userspace tools that read
 * the binary output of the trace buffers do not have access to the string.
 * Instead they just show the address of the string which is not very
 * useful to users.
 *
 * With tracepoint_string(), the string will be registered to the tracing
 * system and exported to userspace via the debugfs/tracing/printk_formats
 * file that maps the string address to the string text. This way userspace
 * tools that read the binary buffers have a way to map the pointers to
 * the ASCII strings they represent.
 *
 * The @str used must be a constant string and persistent as it would not
 * make sense to show a string that no longer exists. But it is still fine
 * to be used with modules, because when modules are unloaded, if they
 * had tracepoints, the ring buffers are cleared too. As long as the string
 * does not change during the life of the module, it is fine to use
 * tracepoint_string() within a module.
 */
#define tracepoint_string(str)						\
	({								\
		static const char *___tp_str __tracepoint_string = str; \
		___tp_str;						\
	})
#define __tracepoint_string	__attribute__((section("__tracepoint_str")))

#ifdef CONFIG_PERF_EVENTS
struct perf_event;

DECLARE_PER_CPU(struct pt_regs, perf_trace_regs);

extern int  perf_trace_init(struct perf_event *event);
extern void perf_trace_destroy(struct perf_event *event);
extern int  perf_trace_add(struct perf_event *event, int flags);
extern void perf_trace_del(struct perf_event *event, int flags);
extern int  ftrace_profile_set_filter(struct perf_event *event, int event_id,
				     char *filter_str);
extern void ftrace_profile_free_filter(struct perf_event *event);
extern void *perf_trace_buf_prepare(int size, unsigned short type,
				    struct pt_regs *regs, int *rctxp);

static inline void
perf_trace_buf_submit(void *raw_data, int size, int rctx, u64 addr,
		       u64 count, struct pt_regs *regs, void *head,
		       struct task_struct *task)
{
	perf_tp_event(addr, count, raw_data, size, regs, head, rctx, task);
}
#endif

#endif /* _LINUX_FTRACE_EVENT_H */