xref: /linux/include/linux/tracepoint.h (revision e8744fbc83188693f3590020b14d50df3387fc5a)
1 /* SPDX-License-Identifier: GPL-2.0-only */
2 #ifndef _LINUX_TRACEPOINT_H
3 #define _LINUX_TRACEPOINT_H
4 
5 /*
6  * Kernel Tracepoint API.
7  *
8  * See Documentation/trace/tracepoints.rst.
9  *
10  * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
11  *
12  * Heavily inspired from the Linux Kernel Markers.
13  */
14 
15 #include <linux/smp.h>
16 #include <linux/srcu.h>
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/rcupdate.h>
20 #include <linux/rcupdate_trace.h>
21 #include <linux/tracepoint-defs.h>
22 #include <linux/static_call.h>
23 
24 struct module;
25 struct tracepoint;
26 struct notifier_block;
27 
28 struct trace_eval_map {
29 	const char		*system;
30 	const char		*eval_string;
31 	unsigned long		eval_value;
32 };
33 
34 #define TRACEPOINT_DEFAULT_PRIO	10
35 
36 extern int
37 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
38 extern int
39 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
40 			       int prio);
41 extern int
42 tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe, void *data,
43 					 int prio);
44 extern int
45 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
46 static inline int
tracepoint_probe_register_may_exist(struct tracepoint * tp,void * probe,void * data)47 tracepoint_probe_register_may_exist(struct tracepoint *tp, void *probe,
48 				    void *data)
49 {
50 	return tracepoint_probe_register_prio_may_exist(tp, probe, data,
51 							TRACEPOINT_DEFAULT_PRIO);
52 }
53 extern void
54 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
55 		void *priv);
56 
57 #ifdef CONFIG_MODULES
58 struct tp_module {
59 	struct list_head list;
60 	struct module *mod;
61 };
62 
63 bool trace_module_has_bad_taint(struct module *mod);
64 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
65 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
66 void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
67 					struct module *, void *),
68 				void *priv);
69 void for_each_tracepoint_in_module(struct module *,
70 				   void (*fct)(struct tracepoint *,
71 					struct module *, void *),
72 				   void *priv);
73 #else
trace_module_has_bad_taint(struct module * mod)74 static inline bool trace_module_has_bad_taint(struct module *mod)
75 {
76 	return false;
77 }
78 static inline
register_tracepoint_module_notifier(struct notifier_block * nb)79 int register_tracepoint_module_notifier(struct notifier_block *nb)
80 {
81 	return 0;
82 }
83 static inline
unregister_tracepoint_module_notifier(struct notifier_block * nb)84 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
85 {
86 	return 0;
87 }
88 static inline
for_each_module_tracepoint(void (* fct)(struct tracepoint *,struct module *,void *),void * priv)89 void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
90 					struct module *, void *),
91 				void *priv)
92 {
93 }
94 static inline
for_each_tracepoint_in_module(struct module * mod,void (* fct)(struct tracepoint *,struct module *,void *),void * priv)95 void for_each_tracepoint_in_module(struct module *mod,
96 				   void (*fct)(struct tracepoint *,
97 					struct module *, void *),
98 				   void *priv)
99 {
100 }
101 #endif /* CONFIG_MODULES */
102 
103 /*
104  * tracepoint_synchronize_unregister must be called between the last tracepoint
105  * probe unregistration and the end of module exit to make sure there is no
106  * caller executing a probe when it is freed.
107  *
108  * An alternative is to use the following for batch reclaim associated
109  * with a given tracepoint:
110  *
111  * - tracepoint_is_faultable() == false: call_rcu()
112  * - tracepoint_is_faultable() == true:  call_rcu_tasks_trace()
113  */
114 #ifdef CONFIG_TRACEPOINTS
tracepoint_synchronize_unregister(void)115 static inline void tracepoint_synchronize_unregister(void)
116 {
117 	synchronize_rcu_tasks_trace();
118 	synchronize_rcu();
119 }
tracepoint_is_faultable(struct tracepoint * tp)120 static inline bool tracepoint_is_faultable(struct tracepoint *tp)
121 {
122 	return tp->ext && tp->ext->faultable;
123 }
124 #else
tracepoint_synchronize_unregister(void)125 static inline void tracepoint_synchronize_unregister(void)
126 { }
tracepoint_is_faultable(struct tracepoint * tp)127 static inline bool tracepoint_is_faultable(struct tracepoint *tp)
128 {
129 	return false;
130 }
131 #endif
132 
133 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
134 extern int syscall_regfunc(void);
135 extern void syscall_unregfunc(void);
136 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
137 
138 #ifndef PARAMS
139 #define PARAMS(args...) args
140 #endif
141 
142 #define TRACE_DEFINE_ENUM(x)
143 #define TRACE_DEFINE_SIZEOF(x)
144 
145 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
tracepoint_ptr_deref(tracepoint_ptr_t * p)146 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
147 {
148 	return offset_to_ptr(p);
149 }
150 
151 #define __TRACEPOINT_ENTRY(name)					\
152 	asm("	.section \"__tracepoints_ptrs\", \"a\"		\n"	\
153 	    "	.balign 4					\n"	\
154 	    "	.long 	__tracepoint_" #name " - .		\n"	\
155 	    "	.previous					\n")
156 #else
tracepoint_ptr_deref(tracepoint_ptr_t * p)157 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
158 {
159 	return *p;
160 }
161 
162 #define __TRACEPOINT_ENTRY(name)					 \
163 	static tracepoint_ptr_t __tracepoint_ptr_##name __used		 \
164 	__section("__tracepoints_ptrs") = &__tracepoint_##name
165 #endif
166 
167 #endif /* _LINUX_TRACEPOINT_H */
168 
169 /*
170  * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
171  *  file ifdef protection.
172  *  This is due to the way trace events work. If a file includes two
173  *  trace event headers under one "CREATE_TRACE_POINTS" the first include
174  *  will override the TRACE_EVENT and break the second include.
175  */
176 
177 #ifndef DECLARE_TRACE
178 
179 #define TP_PROTO(args...)	args
180 #define TP_ARGS(args...)	args
181 #define TP_CONDITION(args...)	args
182 
183 /*
184  * Individual subsystem my have a separate configuration to
185  * enable their tracepoints. By default, this file will create
186  * the tracepoints if CONFIG_TRACEPOINTS is defined. If a subsystem
187  * wants to be able to disable its tracepoints from being created
188  * it can define NOTRACE before including the tracepoint headers.
189  */
190 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
191 #define TRACEPOINTS_ENABLED
192 #endif
193 
194 #ifdef TRACEPOINTS_ENABLED
195 
196 #ifdef CONFIG_HAVE_STATIC_CALL
197 #define __DO_TRACE_CALL(name, args)					\
198 	do {								\
199 		struct tracepoint_func *it_func_ptr;			\
200 		void *__data;						\
201 		it_func_ptr =						\
202 			rcu_dereference_raw((&__tracepoint_##name)->funcs); \
203 		if (it_func_ptr) {					\
204 			__data = (it_func_ptr)->data;			\
205 			static_call(tp_func_##name)(__data, args);	\
206 		}							\
207 	} while (0)
208 #else
209 #define __DO_TRACE_CALL(name, args)	__traceiter_##name(NULL, args)
210 #endif /* CONFIG_HAVE_STATIC_CALL */
211 
212 /*
213  * Declare an exported function that Rust code can call to trigger this
214  * tracepoint. This function does not include the static branch; that is done
215  * in Rust to avoid a function call when the tracepoint is disabled.
216  */
217 #define DEFINE_RUST_DO_TRACE(name, proto, args)
218 #define __DEFINE_RUST_DO_TRACE(name, proto, args)			\
219 	notrace void rust_do_trace_##name(proto)			\
220 	{								\
221 		__do_trace_##name(args);				\
222 	}
223 
224 /*
225  * Make sure the alignment of the structure in the __tracepoints section will
226  * not add unwanted padding between the beginning of the section and the
227  * structure. Force alignment to the same alignment as the section start.
228  *
229  * When lockdep is enabled, we make sure to always test if RCU is
230  * "watching" regardless if the tracepoint is enabled or not. Tracepoints
231  * require RCU to be active, and it should always warn at the tracepoint
232  * site if it is not watching, as it will need to be active when the
233  * tracepoint is enabled.
234  */
235 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto)		\
236 	extern int __traceiter_##name(data_proto);			\
237 	DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name);	\
238 	extern struct tracepoint __tracepoint_##name;			\
239 	extern void rust_do_trace_##name(proto);			\
240 	static inline int						\
241 	register_trace_##name(void (*probe)(data_proto), void *data)	\
242 	{								\
243 		return tracepoint_probe_register(&__tracepoint_##name,	\
244 						(void *)probe, data);	\
245 	}								\
246 	static inline int						\
247 	register_trace_prio_##name(void (*probe)(data_proto), void *data,\
248 				   int prio)				\
249 	{								\
250 		return tracepoint_probe_register_prio(&__tracepoint_##name, \
251 					      (void *)probe, data, prio); \
252 	}								\
253 	static inline int						\
254 	unregister_trace_##name(void (*probe)(data_proto), void *data)	\
255 	{								\
256 		return tracepoint_probe_unregister(&__tracepoint_##name,\
257 						(void *)probe, data);	\
258 	}								\
259 	static inline void						\
260 	check_trace_callback_type_##name(void (*cb)(data_proto))	\
261 	{								\
262 	}								\
263 	static inline bool						\
264 	trace_##name##_enabled(void)					\
265 	{								\
266 		return static_branch_unlikely(&__tracepoint_##name.key);\
267 	}
268 
269 #define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\
270 	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
271 	static inline void __do_trace_##name(proto)			\
272 	{								\
273 		if (cond) {						\
274 			guard(preempt_notrace)();			\
275 			__DO_TRACE_CALL(name, TP_ARGS(args));		\
276 		}							\
277 	}								\
278 	static inline void trace_##name(proto)				\
279 	{								\
280 		if (static_branch_unlikely(&__tracepoint_##name.key))	\
281 			__do_trace_##name(args);			\
282 		if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {		\
283 			WARN_ONCE(!rcu_is_watching(),			\
284 				  "RCU not watching for tracepoint");	\
285 		}							\
286 	}
287 
288 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto)		\
289 	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
290 	static inline void __do_trace_##name(proto)			\
291 	{								\
292 		guard(rcu_tasks_trace)();				\
293 		__DO_TRACE_CALL(name, TP_ARGS(args));			\
294 	}								\
295 	static inline void trace_##name(proto)				\
296 	{								\
297 		might_fault();						\
298 		if (static_branch_unlikely(&__tracepoint_##name.key))	\
299 			__do_trace_##name(args);			\
300 		if (IS_ENABLED(CONFIG_LOCKDEP)) {			\
301 			WARN_ONCE(!rcu_is_watching(),			\
302 				  "RCU not watching for tracepoint");	\
303 		}							\
304 	}
305 
306 /*
307  * We have no guarantee that gcc and the linker won't up-align the tracepoint
308  * structures, so we create an array of pointers that will be used for iteration
309  * on the tracepoints.
310  *
311  * it_func[0] is never NULL because there is at least one element in the array
312  * when the array itself is non NULL.
313  */
314 #define __DEFINE_TRACE_EXT(_name, _ext, proto, args)			\
315 	static const char __tpstrtab_##_name[]				\
316 	__section("__tracepoints_strings") = #_name;			\
317 	extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name);	\
318 	int __traceiter_##_name(void *__data, proto);			\
319 	void __probestub_##_name(void *__data, proto);			\
320 	struct tracepoint __tracepoint_##_name	__used			\
321 	__section("__tracepoints") = {					\
322 		.name = __tpstrtab_##_name,				\
323 		.key = STATIC_KEY_FALSE_INIT,				\
324 		.static_call_key = &STATIC_CALL_KEY(tp_func_##_name),	\
325 		.static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
326 		.iterator = &__traceiter_##_name,			\
327 		.probestub = &__probestub_##_name,			\
328 		.funcs = NULL,						\
329 		.ext = _ext,						\
330 	};								\
331 	__TRACEPOINT_ENTRY(_name);					\
332 	int __traceiter_##_name(void *__data, proto)			\
333 	{								\
334 		struct tracepoint_func *it_func_ptr;			\
335 		void *it_func;						\
336 									\
337 		it_func_ptr =						\
338 			rcu_dereference_raw((&__tracepoint_##_name)->funcs); \
339 		if (it_func_ptr) {					\
340 			do {						\
341 				it_func = READ_ONCE((it_func_ptr)->func); \
342 				__data = (it_func_ptr)->data;		\
343 				((void(*)(void *, proto))(it_func))(__data, args); \
344 			} while ((++it_func_ptr)->func);		\
345 		}							\
346 		return 0;						\
347 	}								\
348 	void __probestub_##_name(void *__data, proto)			\
349 	{								\
350 	}								\
351 	DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name);	\
352 	DEFINE_RUST_DO_TRACE(_name, TP_PROTO(proto), TP_ARGS(args))
353 
354 #define DEFINE_TRACE_FN(_name, _reg, _unreg, _proto, _args)		\
355 	static struct tracepoint_ext __tracepoint_ext_##_name = {	\
356 		.regfunc = _reg,					\
357 		.unregfunc = _unreg,					\
358 		.faultable = false,					\
359 	};								\
360 	__DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
361 
362 #define DEFINE_TRACE_SYSCALL(_name, _reg, _unreg, _proto, _args)	\
363 	static struct tracepoint_ext __tracepoint_ext_##_name = {	\
364 		.regfunc = _reg,					\
365 		.unregfunc = _unreg,					\
366 		.faultable = true,					\
367 	};								\
368 	__DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
369 
370 #define DEFINE_TRACE(_name, _proto, _args)				\
371 	__DEFINE_TRACE_EXT(_name, NULL, PARAMS(_proto), PARAMS(_args));
372 
373 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)				\
374 	EXPORT_SYMBOL_GPL(__tracepoint_##name);				\
375 	EXPORT_SYMBOL_GPL(__traceiter_##name);				\
376 	EXPORT_STATIC_CALL_GPL(tp_func_##name)
377 #define EXPORT_TRACEPOINT_SYMBOL(name)					\
378 	EXPORT_SYMBOL(__tracepoint_##name);				\
379 	EXPORT_SYMBOL(__traceiter_##name);				\
380 	EXPORT_STATIC_CALL(tp_func_##name)
381 
382 
383 #else /* !TRACEPOINTS_ENABLED */
384 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto)		\
385 	static inline void trace_##name(proto)				\
386 	{ }								\
387 	static inline int						\
388 	register_trace_##name(void (*probe)(data_proto),		\
389 			      void *data)				\
390 	{								\
391 		return -ENOSYS;						\
392 	}								\
393 	static inline int						\
394 	unregister_trace_##name(void (*probe)(data_proto),		\
395 				void *data)				\
396 	{								\
397 		return -ENOSYS;						\
398 	}								\
399 	static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
400 	{								\
401 	}								\
402 	static inline bool						\
403 	trace_##name##_enabled(void)					\
404 	{								\
405 		return false;						\
406 	}
407 
408 #define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\
409 	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
410 
411 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto)		\
412 	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
413 
414 #define DEFINE_TRACE_FN(name, reg, unreg, proto, args)
415 #define DEFINE_TRACE_SYSCALL(name, reg, unreg, proto, args)
416 #define DEFINE_TRACE(name, proto, args)
417 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
418 #define EXPORT_TRACEPOINT_SYMBOL(name)
419 
420 #endif /* TRACEPOINTS_ENABLED */
421 
422 #ifdef CONFIG_TRACING
423 /**
424  * tracepoint_string - register constant persistent string to trace system
425  * @str - a constant persistent string that will be referenced in tracepoints
426  *
427  * If constant strings are being used in tracepoints, it is faster and
428  * more efficient to just save the pointer to the string and reference
429  * that with a printf "%s" instead of saving the string in the ring buffer
430  * and wasting space and time.
431  *
432  * The problem with the above approach is that userspace tools that read
433  * the binary output of the trace buffers do not have access to the string.
434  * Instead they just show the address of the string which is not very
435  * useful to users.
436  *
437  * With tracepoint_string(), the string will be registered to the tracing
438  * system and exported to userspace via the debugfs/tracing/printk_formats
439  * file that maps the string address to the string text. This way userspace
440  * tools that read the binary buffers have a way to map the pointers to
441  * the ASCII strings they represent.
442  *
443  * The @str used must be a constant string and persistent as it would not
444  * make sense to show a string that no longer exists. But it is still fine
445  * to be used with modules, because when modules are unloaded, if they
446  * had tracepoints, the ring buffers are cleared too. As long as the string
447  * does not change during the life of the module, it is fine to use
448  * tracepoint_string() within a module.
449  */
450 #define tracepoint_string(str)						\
451 	({								\
452 		static const char *___tp_str __tracepoint_string = str; \
453 		___tp_str;						\
454 	})
455 #define __tracepoint_string	__used __section("__tracepoint_str")
456 #else
457 /*
458  * tracepoint_string() is used to save the string address for userspace
459  * tracing tools. When tracing isn't configured, there's no need to save
460  * anything.
461  */
462 # define tracepoint_string(str) str
463 # define __tracepoint_string
464 #endif
465 
466 #define DECLARE_TRACE(name, proto, args)				\
467 	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),		\
468 			cpu_online(raw_smp_processor_id()),		\
469 			PARAMS(void *__data, proto))
470 
471 #define DECLARE_TRACE_CONDITION(name, proto, args, cond)		\
472 	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),		\
473 			cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
474 			PARAMS(void *__data, proto))
475 
476 #define DECLARE_TRACE_SYSCALL(name, proto, args)			\
477 	__DECLARE_TRACE_SYSCALL(name, PARAMS(proto), PARAMS(args),	\
478 				PARAMS(void *__data, proto))
479 
480 #define TRACE_EVENT_FLAGS(event, flag)
481 
482 #define TRACE_EVENT_PERF_PERM(event, expr...)
483 
484 #endif /* DECLARE_TRACE */
485 
486 #ifndef TRACE_EVENT
487 /*
488  * For use with the TRACE_EVENT macro:
489  *
490  * We define a tracepoint, its arguments, its printk format
491  * and its 'fast binary record' layout.
492  *
493  * Firstly, name your tracepoint via TRACE_EVENT(name : the
494  * 'subsystem_event' notation is fine.
495  *
496  * Think about this whole construct as the
497  * 'trace_sched_switch() function' from now on.
498  *
499  *
500  *  TRACE_EVENT(sched_switch,
501  *
502  *	*
503  *	* A function has a regular function arguments
504  *	* prototype, declare it via TP_PROTO():
505  *	*
506  *
507  *	TP_PROTO(struct rq *rq, struct task_struct *prev,
508  *		 struct task_struct *next),
509  *
510  *	*
511  *	* Define the call signature of the 'function'.
512  *	* (Design sidenote: we use this instead of a
513  *	*  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
514  *	*
515  *
516  *	TP_ARGS(rq, prev, next),
517  *
518  *	*
519  *	* Fast binary tracing: define the trace record via
520  *	* TP_STRUCT__entry(). You can think about it like a
521  *	* regular C structure local variable definition.
522  *	*
523  *	* This is how the trace record is structured and will
524  *	* be saved into the ring buffer. These are the fields
525  *	* that will be exposed to user-space in
526  *	* /sys/kernel/tracing/events/<*>/format.
527  *	*
528  *	* The declared 'local variable' is called '__entry'
529  *	*
530  *	* __field(pid_t, prev_pid) is equivalent to a standard declaration:
531  *	*
532  *	*	pid_t	prev_pid;
533  *	*
534  *	* __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
535  *	*
536  *	*	char	prev_comm[TASK_COMM_LEN];
537  *	*
538  *
539  *	TP_STRUCT__entry(
540  *		__array(	char,	prev_comm,	TASK_COMM_LEN	)
541  *		__field(	pid_t,	prev_pid			)
542  *		__field(	int,	prev_prio			)
543  *		__array(	char,	next_comm,	TASK_COMM_LEN	)
544  *		__field(	pid_t,	next_pid			)
545  *		__field(	int,	next_prio			)
546  *	),
547  *
548  *	*
549  *	* Assign the entry into the trace record, by embedding
550  *	* a full C statement block into TP_fast_assign(). You
551  *	* can refer to the trace record as '__entry' -
552  *	* otherwise you can put arbitrary C code in here.
553  *	*
554  *	* Note: this C code will execute every time a trace event
555  *	* happens, on an active tracepoint.
556  *	*
557  *
558  *	TP_fast_assign(
559  *		memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
560  *		__entry->prev_pid	= prev->pid;
561  *		__entry->prev_prio	= prev->prio;
562  *		memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
563  *		__entry->next_pid	= next->pid;
564  *		__entry->next_prio	= next->prio;
565  *	),
566  *
567  *	*
568  *	* Formatted output of a trace record via TP_printk().
569  *	* This is how the tracepoint will appear under ftrace
570  *	* plugins that make use of this tracepoint.
571  *	*
572  *	* (raw-binary tracing wont actually perform this step.)
573  *	*
574  *
575  *	TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
576  *		__entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
577  *		__entry->next_comm, __entry->next_pid, __entry->next_prio),
578  *
579  * );
580  *
581  * This macro construct is thus used for the regular printk format
582  * tracing setup, it is used to construct a function pointer based
583  * tracepoint callback (this is used by programmatic plugins and
584  * can also by used by generic instrumentation like SystemTap), and
585  * it is also used to expose a structured trace record in
586  * /sys/kernel/tracing/events/.
587  *
588  * A set of (un)registration functions can be passed to the variant
589  * TRACE_EVENT_FN to perform any (un)registration work.
590  */
591 
592 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
593 #define DEFINE_EVENT(template, name, proto, args)		\
594 	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
595 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
596 	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
597 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\
598 	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
599 #define DEFINE_EVENT_CONDITION(template, name, proto,		\
600 			       args, cond)			\
601 	DECLARE_TRACE_CONDITION(name, PARAMS(proto),		\
602 				PARAMS(args), PARAMS(cond))
603 
604 #define TRACE_EVENT(name, proto, args, struct, assign, print)	\
605 	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
606 #define TRACE_EVENT_FN(name, proto, args, struct,		\
607 		assign, print, reg, unreg)			\
608 	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
609 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct,		\
610 		assign, print, reg, unreg)			\
611 	DECLARE_TRACE_CONDITION(name, PARAMS(proto),	\
612 			PARAMS(args), PARAMS(cond))
613 #define TRACE_EVENT_CONDITION(name, proto, args, cond,		\
614 			      struct, assign, print)		\
615 	DECLARE_TRACE_CONDITION(name, PARAMS(proto),		\
616 				PARAMS(args), PARAMS(cond))
617 #define TRACE_EVENT_SYSCALL(name, proto, args, struct, assign,	\
618 			    print, reg, unreg)			\
619 	DECLARE_TRACE_SYSCALL(name, PARAMS(proto), PARAMS(args))
620 
621 #define TRACE_EVENT_FLAGS(event, flag)
622 
623 #define TRACE_EVENT_PERF_PERM(event, expr...)
624 
625 #define DECLARE_EVENT_NOP(name, proto, args)				\
626 	static inline void trace_##name(proto)				\
627 	{ }								\
628 	static inline bool trace_##name##_enabled(void)			\
629 	{								\
630 		return false;						\
631 	}
632 
633 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print)	\
634 	DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
635 
636 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
637 #define DEFINE_EVENT_NOP(template, name, proto, args)			\
638 	DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
639 
640 #endif /* ifdef TRACE_EVENT (see note above) */
641