[deliverable/linux.git] / include / linux / tracepoint.h

#ifndef _LINUX_TRACEPOINT_H
#define _LINUX_TRACEPOINT_H

/*
 * Kernel Tracepoint API.
 *
 * See Documentation/trace/tracepoints.txt.
 *
 * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
 *
 * Heavily inspired from the Linux Kernel Markers.
 *
 * This file is released under the GPLv2.
 * See the file COPYING for more details.
 */

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/rcupdate.h>
#include <linux/static_key.h>

struct module;
struct tracepoint;

struct tracepoint_func {
	void *func;
	void *data;
};

struct tracepoint {
	const char *name;		/* Tracepoint name */
	struct static_key key;
	void (*regfunc)(void);
	void (*unregfunc)(void);
	struct tracepoint_func __rcu *funcs;
};

/*
 * Connect a probe to a tracepoint.
 * Internal API, should not be used directly.
 */
extern int tracepoint_probe_register(const char *name, void *probe, void *data);

/*
 * Disconnect a probe from a tracepoint.
 * Internal API, should not be used directly.
 */
extern int
tracepoint_probe_unregister(const char *name, void *probe, void *data);

extern int tracepoint_probe_register_noupdate(const char *name, void *probe,
					      void *data);
extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
						void *data);
extern void tracepoint_probe_update_all(void);

#ifdef CONFIG_MODULES
struct tp_module {
	struct list_head list;
	unsigned int num_tracepoints;
	struct tracepoint * const *tracepoints_ptrs;
};
bool trace_module_has_bad_taint(struct module *mod);
#else
static inline bool trace_module_has_bad_taint(struct module *mod)
{
	return false;
}
#endif /* CONFIG_MODULES */

struct tracepoint_iter {
#ifdef CONFIG_MODULES
	struct tp_module *module;
#endif /* CONFIG_MODULES */
	struct tracepoint * const *tracepoint;
};

extern void tracepoint_iter_start(struct tracepoint_iter *iter);
extern void tracepoint_iter_next(struct tracepoint_iter *iter);
extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
extern void tracepoint_iter_reset(struct tracepoint_iter *iter);

/*
 * tracepoint_synchronize_unregister must be called between the last tracepoint
 * probe unregistration and the end of module exit to make sure there is no
 * caller executing a probe when it is freed.
 */
static inline void tracepoint_synchronize_unregister(void)
{
	synchronize_sched();
}

#define PARAMS(args...) args

#endif /* _LINUX_TRACEPOINT_H */

/*
 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
 *  file ifdef protection.
 *  This is due to the way trace events work. If a file includes two
 *  trace event headers under one "CREATE_TRACE_POINTS" the first include
 *  will override the TRACE_EVENT and break the second include.
 */

#ifndef DECLARE_TRACE

#define TP_PROTO(args...)	args
#define TP_ARGS(args...)	args
#define TP_CONDITION(args...)	args

#ifdef CONFIG_TRACEPOINTS

/*
 * it_func[0] is never NULL because there is at least one element in the array
 * when the array itself is non NULL.
 *
 * Note, the proto and args passed in includes "__data" as the first parameter.
 * The reason for this is to handle the "void" prototype. If a tracepoint
 * has a "void" prototype, then it is invalid to declare a function
 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
 */
#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu)		\
	do {								\
		struct tracepoint_func *it_func_ptr;			\
		void *it_func;						\
		void *__data;						\
									\
		if (!(cond))						\
			return;						\
		prercu;							\
		rcu_read_lock_sched_notrace();				\
		it_func_ptr = rcu_dereference_sched((tp)->funcs);	\
		if (it_func_ptr) {					\
			do {						\
				it_func = (it_func_ptr)->func;		\
				__data = (it_func_ptr)->data;		\
				((void(*)(proto))(it_func))(args);	\
			} while ((++it_func_ptr)->func);		\
		}							\
		rcu_read_unlock_sched_notrace();			\
		postrcu;						\
	} while (0)

#ifndef MODULE
#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)	\
	static inline void trace_##name##_rcuidle(proto)		\
	{								\
		if (static_key_false(&__tracepoint_##name.key))		\
			__DO_TRACE(&__tracepoint_##name,		\
				TP_PROTO(data_proto),			\
				TP_ARGS(data_args),			\
				TP_CONDITION(cond),			\
				rcu_irq_enter(),			\
				rcu_irq_exit());			\
	}
#else
#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
#endif

/*
 * Make sure the alignment of the structure in the __tracepoints section will
 * not add unwanted padding between the beginning of the section and the
 * structure. Force alignment to the same alignment as the section start.
 */
#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
	extern struct tracepoint __tracepoint_##name;			\
	static inline void trace_##name(proto)				\
	{								\
		if (static_key_false(&__tracepoint_##name.key))		\
			__DO_TRACE(&__tracepoint_##name,		\
				TP_PROTO(data_proto),			\
				TP_ARGS(data_args),			\
				TP_CONDITION(cond),,);			\
	}								\
	__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),		\
		PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))	\
	static inline int						\
	register_trace_##name(void (*probe)(data_proto), void *data)	\
	{								\
		return tracepoint_probe_register(#name, (void *)probe,	\
						 data);			\
	}								\
	static inline int						\
	unregister_trace_##name(void (*probe)(data_proto), void *data)	\
	{								\
		return tracepoint_probe_unregister(#name, (void *)probe, \
						   data);		\
	}								\
	static inline void						\
	check_trace_callback_type_##name(void (*cb)(data_proto))	\
	{								\
	}

/*
 * We have no guarantee that gcc and the linker won't up-align the tracepoint
 * structures, so we create an array of pointers that will be used for iteration
 * on the tracepoints.
 */
#define DEFINE_TRACE_FN(name, reg, unreg)				 \
	static const char __tpstrtab_##name[]				 \
	__attribute__((section("__tracepoints_strings"))) = #name;	 \
	struct tracepoint __tracepoint_##name				 \
	__attribute__((section("__tracepoints"))) =			 \
		{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
	static struct tracepoint * const __tracepoint_ptr_##name __used	 \
	__attribute__((section("__tracepoints_ptrs"))) =		 \
		&__tracepoint_##name;

#define DEFINE_TRACE(name)						\
	DEFINE_TRACE_FN(name, NULL, NULL);

#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)				\
	EXPORT_SYMBOL_GPL(__tracepoint_##name)
#define EXPORT_TRACEPOINT_SYMBOL(name)					\
	EXPORT_SYMBOL(__tracepoint_##name)

#else /* !CONFIG_TRACEPOINTS */
#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
	static inline void trace_##name(proto)				\
	{ }								\
	static inline void trace_##name##_rcuidle(proto)		\
	{ }								\
	static inline int						\
	register_trace_##name(void (*probe)(data_proto),		\
			      void *data)				\
	{								\
		return -ENOSYS;						\
	}								\
	static inline int						\
	unregister_trace_##name(void (*probe)(data_proto),		\
				void *data)				\
	{								\
		return -ENOSYS;						\
	}								\
	static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
	{								\
	}

#define DEFINE_TRACE_FN(name, reg, unreg)
#define DEFINE_TRACE(name)
#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
#define EXPORT_TRACEPOINT_SYMBOL(name)

#endif /* CONFIG_TRACEPOINTS */

/*
 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
 * (void). "void" is a special value in a function prototype and can
 * not be combined with other arguments. Since the DECLARE_TRACE()
 * macro adds a data element at the beginning of the prototype,
 * we need a way to differentiate "(void *data, proto)" from
 * "(void *data, void)". The second prototype is invalid.
 *
 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
 * and "void *__data" as the callback prototype.
 *
 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
 * "void *__data, proto" as the callback prototype.
 */
#define DECLARE_TRACE_NOARGS(name)					\
		__DECLARE_TRACE(name, void, , 1, void *__data, __data)

#define DECLARE_TRACE(name, proto, args)				\
		__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1,	\
				PARAMS(void *__data, proto),		\
				PARAMS(__data, args))

#define DECLARE_TRACE_CONDITION(name, proto, args, cond)		\
	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
			PARAMS(void *__data, proto),			\
			PARAMS(__data, args))

#define TRACE_EVENT_FLAGS(event, flag)

#define TRACE_EVENT_PERF_PERM(event, expr...)

#endif /* DECLARE_TRACE */

#ifndef TRACE_EVENT
/*
 * For use with the TRACE_EVENT macro:
 *
 * We define a tracepoint, its arguments, its printk format
 * and its 'fast binary record' layout.
 *
 * Firstly, name your tracepoint via TRACE_EVENT(name : the
 * 'subsystem_event' notation is fine.
 *
 * Think about this whole construct as the
 * 'trace_sched_switch() function' from now on.
 *
 *
 *  TRACE_EVENT(sched_switch,
 *
 *	*
 *	* A function has a regular function arguments
 *	* prototype, declare it via TP_PROTO():
 *	*
 *
 *	TP_PROTO(struct rq *rq, struct task_struct *prev,
 *		 struct task_struct *next),
 *
 *	*
 *	* Define the call signature of the 'function'.
 *	* (Design sidenote: we use this instead of a
 *	*  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 *	*
 *
 *	TP_ARGS(rq, prev, next),
 *
 *	*
 *	* Fast binary tracing: define the trace record via
 *	* TP_STRUCT__entry(). You can think about it like a
 *	* regular C structure local variable definition.
 *	*
 *	* This is how the trace record is structured and will
 *	* be saved into the ring buffer. These are the fields
 *	* that will be exposed to user-space in
 *	* /sys/kernel/debug/tracing/events/<*>/format.
 *	*
 *	* The declared 'local variable' is called '__entry'
 *	*
 *	* __field(pid_t, prev_prid) is equivalent to a standard declariton:
 *	*
 *	*	pid_t	prev_pid;
 *	*
 *	* __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 *	*
 *	*	char	prev_comm[TASK_COMM_LEN];
 *	*
 *
 *	TP_STRUCT__entry(
 *		__array(	char,	prev_comm,	TASK_COMM_LEN	)
 *		__field(	pid_t,	prev_pid			)
 *		__field(	int,	prev_prio			)
 *		__array(	char,	next_comm,	TASK_COMM_LEN	)
 *		__field(	pid_t,	next_pid			)
 *		__field(	int,	next_prio			)
 *	),
 *
 *	*
 *	* Assign the entry into the trace record, by embedding
 *	* a full C statement block into TP_fast_assign(). You
 *	* can refer to the trace record as '__entry' -
 *	* otherwise you can put arbitrary C code in here.
 *	*
 *	* Note: this C code will execute every time a trace event
 *	* happens, on an active tracepoint.
 *	*
 *
 *	TP_fast_assign(
 *		memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 *		__entry->prev_pid	= prev->pid;
 *		__entry->prev_prio	= prev->prio;
 *		memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 *		__entry->next_pid	= next->pid;
 *		__entry->next_prio	= next->prio;
 *	),
 *
 *	*
 *	* Formatted output of a trace record via TP_printk().
 *	* This is how the tracepoint will appear under ftrace
 *	* plugins that make use of this tracepoint.
 *	*
 *	* (raw-binary tracing wont actually perform this step.)
 *	*
 *
 *	TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
 *		__entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 *		__entry->next_comm, __entry->next_pid, __entry->next_prio),
 *
 * );
 *
 * This macro construct is thus used for the regular printk format
 * tracing setup, it is used to construct a function pointer based
 * tracepoint callback (this is used by programmatic plugins and
 * can also by used by generic instrumentation like SystemTap), and
 * it is also used to expose a structured trace record in
 * /sys/kernel/debug/tracing/events/.
 *
 * A set of (un)registration functions can be passed to the variant
 * TRACE_EVENT_FN to perform any (un)registration work.
 */

#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
#define DEFINE_EVENT(template, name, proto, args)		\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define DEFINE_EVENT_CONDITION(template, name, proto,		\
			       args, cond)			\
	DECLARE_TRACE_CONDITION(name, PARAMS(proto),		\
				PARAMS(args), PARAMS(cond))

#define TRACE_EVENT(name, proto, args, struct, assign, print)	\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define TRACE_EVENT_FN(name, proto, args, struct,		\
		assign, print, reg, unreg)			\
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
#define TRACE_EVENT_CONDITION(name, proto, args, cond,		\
			      struct, assign, print)		\
	DECLARE_TRACE_CONDITION(name, PARAMS(proto),		\
				PARAMS(args), PARAMS(cond))

#define TRACE_EVENT_FLAGS(event, flag)

#define TRACE_EVENT_PERF_PERM(event, expr...)

#endif /* ifdef TRACE_EVENT (see note above) */
Commit	Line	Data
	1	#ifndef _LINUX_TRACEPOINT_H
	2	#define _LINUX_TRACEPOINT_H
	3
	4	/*
	5	* Kernel Tracepoint API.
	6	*
	7	* See Documentation/trace/tracepoints.txt.
	8	*
	9	* (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
	10	*
	11	* Heavily inspired from the Linux Kernel Markers.
	12	*
	13	* This file is released under the GPLv2.
	14	* See the file COPYING for more details.
	15	*/
	16
	17	#include <linux/errno.h>
	18	#include <linux/types.h>
	19	#include <linux/rcupdate.h>
	20	#include <linux/static_key.h>
	21
	22	struct module;
	23	struct tracepoint;
	24
	25	struct tracepoint_func {
	26	void *func;
	27	void *data;
	28	};
	29
	30	struct tracepoint {
	31	const char name; / Tracepoint name */
	32	struct static_key key;
	33	void (*regfunc)(void);
	34	void (*unregfunc)(void);
	35	struct tracepoint_func __rcu *funcs;
	36	};
	37
	38	/*
	39	* Connect a probe to a tracepoint.
	40	* Internal API, should not be used directly.
	41	*/
	42	extern int tracepoint_probe_register(const char name, void probe, void *data);
	43
	44	/*
	45	* Disconnect a probe from a tracepoint.
	46	* Internal API, should not be used directly.
	47	*/
	48	extern int
	49	tracepoint_probe_unregister(const char name, void probe, void *data);
	50
	51	extern int tracepoint_probe_register_noupdate(const char name, void probe,
	52	void *data);
	53	extern int tracepoint_probe_unregister_noupdate(const char name, void probe,
	54	void *data);
	55	extern void tracepoint_probe_update_all(void);
	56
	57	#ifdef CONFIG_MODULES
	58	struct tp_module {
	59	struct list_head list;
	60	unsigned int num_tracepoints;
	61	struct tracepoint * const *tracepoints_ptrs;
	62	};
	63	bool trace_module_has_bad_taint(struct module *mod);
	64	#else
	65	static inline bool trace_module_has_bad_taint(struct module *mod)
	66	{
	67	return false;
	68	}
	69	#endif /* CONFIG_MODULES */
	70
	71	struct tracepoint_iter {
	72	#ifdef CONFIG_MODULES
	73	struct tp_module *module;
	74	#endif /* CONFIG_MODULES */
	75	struct tracepoint * const *tracepoint;
	76	};
	77
	78	extern void tracepoint_iter_start(struct tracepoint_iter *iter);
	79	extern void tracepoint_iter_next(struct tracepoint_iter *iter);
	80	extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
	81	extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
	82
	83	/*
	84	* tracepoint_synchronize_unregister must be called between the last tracepoint
	85	* probe unregistration and the end of module exit to make sure there is no
	86	* caller executing a probe when it is freed.
	87	*/
	88	static inline void tracepoint_synchronize_unregister(void)
	89	{
	90	synchronize_sched();
	91	}
	92
	93	#define PARAMS(args...) args
	94
	95	#endif /* _LINUX_TRACEPOINT_H */
	96
	97	/*
	98	* Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
	99	* file ifdef protection.
	100	* This is due to the way trace events work. If a file includes two
	101	* trace event headers under one "CREATE_TRACE_POINTS" the first include
	102	* will override the TRACE_EVENT and break the second include.
	103	*/
	104
	105	#ifndef DECLARE_TRACE
	106
	107	#define TP_PROTO(args...) args
	108	#define TP_ARGS(args...) args
	109	#define TP_CONDITION(args...) args
	110
	111	#ifdef CONFIG_TRACEPOINTS
	112
	113	/*
	114	* it_func[0] is never NULL because there is at least one element in the array
	115	* when the array itself is non NULL.
	116	*
	117	* Note, the proto and args passed in includes "__data" as the first parameter.
	118	* The reason for this is to handle the "void" prototype. If a tracepoint
	119	* has a "void" prototype, then it is invalid to declare a function
	120	* as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
	121	* "void data", where as the DECLARE_TRACE() will pass in "void data, proto".
	122	*/
	123	#define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
	124	do { \
	125	struct tracepoint_func *it_func_ptr; \
	126	void *it_func; \
	127	void *__data; \
	128	\
	129	if (!(cond)) \
	130	return; \
	131	prercu; \
	132	rcu_read_lock_sched_notrace(); \
	133	it_func_ptr = rcu_dereference_sched((tp)->funcs); \
	134	if (it_func_ptr) { \
	135	do { \
	136	it_func = (it_func_ptr)->func; \
	137	__data = (it_func_ptr)->data; \
	138	((void(*)(proto))(it_func))(args); \
	139	} while ((++it_func_ptr)->func); \
	140	} \
	141	rcu_read_unlock_sched_notrace(); \
	142	postrcu; \
	143	} while (0)
	144
	145	#ifndef MODULE
	146	#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
	147	static inline void trace_##name##_rcuidle(proto) \
	148	{ \
	149	if (static_key_false(&__tracepoint_##name.key)) \
	150	__DO_TRACE(&__tracepoint_##name, \
	151	TP_PROTO(data_proto), \
	152	TP_ARGS(data_args), \
	153	TP_CONDITION(cond), \
	154	rcu_irq_enter(), \
	155	rcu_irq_exit()); \
	156	}
	157	#else
	158	#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
	159	#endif
	160
	161	/*
	162	* Make sure the alignment of the structure in the __tracepoints section will
	163	* not add unwanted padding between the beginning of the section and the
	164	* structure. Force alignment to the same alignment as the section start.
	165	*/
	166	#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
	167	extern struct tracepoint __tracepoint_##name; \
	168	static inline void trace_##name(proto) \
	169	{ \
	170	if (static_key_false(&__tracepoint_##name.key)) \
	171	__DO_TRACE(&__tracepoint_##name, \
	172	TP_PROTO(data_proto), \
	173	TP_ARGS(data_args), \
	174	TP_CONDITION(cond),,); \
	175	} \
	176	__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
	177	PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
	178	static inline int \
	179	register_trace_##name(void (probe)(data_proto), void data) \
	180	{ \
	181	return tracepoint_probe_register(#name, (void *)probe, \
	182	data); \
	183	} \
	184	static inline int \
	185	unregister_trace_##name(void (probe)(data_proto), void data) \
	186	{ \
	187	return tracepoint_probe_unregister(#name, (void *)probe, \
	188	data); \
	189	} \
	190	static inline void \
	191	check_trace_callback_type_##name(void (*cb)(data_proto)) \
	192	{ \
	193	}
	194
	195	/*
	196	* We have no guarantee that gcc and the linker won't up-align the tracepoint
	197	* structures, so we create an array of pointers that will be used for iteration
	198	* on the tracepoints.
	199	*/
	200	#define DEFINE_TRACE_FN(name, reg, unreg) \
	201	static const char __tpstrtab_##name[] \
	202	__attribute__((section("__tracepoints_strings"))) = #name; \
	203	struct tracepoint __tracepoint_##name \
	204	__attribute__((section("__tracepoints"))) = \
	205	{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
	206	static struct tracepoint * const __tracepoint_ptr_##name __used \
	207	__attribute__((section("__tracepoints_ptrs"))) = \
	208	&__tracepoint_##name;
	209
	210	#define DEFINE_TRACE(name) \
	211	DEFINE_TRACE_FN(name, NULL, NULL);
	212
	213	#define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
	214	EXPORT_SYMBOL_GPL(__tracepoint_##name)
	215	#define EXPORT_TRACEPOINT_SYMBOL(name) \
	216	EXPORT_SYMBOL(__tracepoint_##name)
	217
	218	#else /* !CONFIG_TRACEPOINTS */
	219	#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
	220	static inline void trace_##name(proto) \
	221	{ } \
	222	static inline void trace_##name##_rcuidle(proto) \
	223	{ } \
	224	static inline int \
	225	register_trace_##name(void (*probe)(data_proto), \
	226	void *data) \
	227	{ \
	228	return -ENOSYS; \
	229	} \
	230	static inline int \
	231	unregister_trace_##name(void (*probe)(data_proto), \
	232	void *data) \
	233	{ \
	234	return -ENOSYS; \
	235	} \
	236	static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
	237	{ \
	238	}
	239
	240	#define DEFINE_TRACE_FN(name, reg, unreg)
	241	#define DEFINE_TRACE(name)
	242	#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
	243	#define EXPORT_TRACEPOINT_SYMBOL(name)
	244
	245	#endif /* CONFIG_TRACEPOINTS */
	246
	247	/*
	248	* The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
	249	* (void). "void" is a special value in a function prototype and can
	250	* not be combined with other arguments. Since the DECLARE_TRACE()
	251	* macro adds a data element at the beginning of the prototype,
	252	* we need a way to differentiate "(void *data, proto)" from
	253	* "(void *data, void)". The second prototype is invalid.
	254	*
	255	* DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
	256	* and "void *__data" as the callback prototype.
	257	*
	258	* DECLARE_TRACE() passes "proto" as the tracepoint protoype and
	259	* "void *__data, proto" as the callback prototype.
	260	*/
	261	#define DECLARE_TRACE_NOARGS(name) \
	262	__DECLARE_TRACE(name, void, , 1, void *__data, __data)
	263
	264	#define DECLARE_TRACE(name, proto, args) \
	265	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
	266	PARAMS(void *__data, proto), \
	267	PARAMS(__data, args))
	268
	269	#define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
	270	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
	271	PARAMS(void *__data, proto), \
	272	PARAMS(__data, args))
	273
	274	#define TRACE_EVENT_FLAGS(event, flag)
	275
	276	#define TRACE_EVENT_PERF_PERM(event, expr...)
	277
	278	#endif /* DECLARE_TRACE */
	279
	280	#ifndef TRACE_EVENT
	281	/*
	282	* For use with the TRACE_EVENT macro:
	283	*
	284	* We define a tracepoint, its arguments, its printk format
	285	* and its 'fast binary record' layout.
	286	*
	287	* Firstly, name your tracepoint via TRACE_EVENT(name : the
	288	* 'subsystem_event' notation is fine.
	289	*
	290	* Think about this whole construct as the
	291	* 'trace_sched_switch() function' from now on.
	292	*
	293	*
	294	* TRACE_EVENT(sched_switch,
	295	*
	296	* *
	297	* * A function has a regular function arguments
	298	* * prototype, declare it via TP_PROTO():
	299	* *
	300	*
	301	* TP_PROTO(struct rq rq, struct task_struct prev,
	302	* struct task_struct *next),
	303	*
	304	* *
	305	* * Define the call signature of the 'function'.
	306	* * (Design sidenote: we use this instead of a
	307	* * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
	308	* *
	309	*
	310	* TP_ARGS(rq, prev, next),
	311	*
	312	* *
	313	* * Fast binary tracing: define the trace record via
	314	* * TP_STRUCT__entry(). You can think about it like a
	315	* * regular C structure local variable definition.
	316	* *
	317	* * This is how the trace record is structured and will
	318	* * be saved into the ring buffer. These are the fields
	319	* * that will be exposed to user-space in
	320	* * /sys/kernel/debug/tracing/events/<*>/format.
	321	* *
	322	* * The declared 'local variable' is called '__entry'
	323	* *
	324	* * __field(pid_t, prev_prid) is equivalent to a standard declariton:
	325	* *
	326	* * pid_t prev_pid;
	327	* *
	328	* * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
	329	* *
	330	* * char prev_comm[TASK_COMM_LEN];
	331	* *
	332	*
	333	* TP_STRUCT__entry(
	334	* __array( char, prev_comm, TASK_COMM_LEN )
	335	* __field( pid_t, prev_pid )
	336	* __field( int, prev_prio )
	337	* __array( char, next_comm, TASK_COMM_LEN )
	338	* __field( pid_t, next_pid )
	339	* __field( int, next_prio )
	340	* ),
	341	*
	342	* *
	343	* * Assign the entry into the trace record, by embedding
	344	* * a full C statement block into TP_fast_assign(). You
	345	* * can refer to the trace record as '__entry' -
	346	* * otherwise you can put arbitrary C code in here.
	347	* *
	348	* * Note: this C code will execute every time a trace event
	349	* * happens, on an active tracepoint.
	350	* *
	351	*
	352	* TP_fast_assign(
	353	* memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
	354	* __entry->prev_pid = prev->pid;
	355	* __entry->prev_prio = prev->prio;
	356	* memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
	357	* __entry->next_pid = next->pid;
	358	* __entry->next_prio = next->prio;
	359	* ),
	360	*
	361	* *
	362	* * Formatted output of a trace record via TP_printk().
	363	* * This is how the tracepoint will appear under ftrace
	364	* * plugins that make use of this tracepoint.
	365	* *
	366	* * (raw-binary tracing wont actually perform this step.)
	367	* *
	368	*
	369	* TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
	370	* __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
	371	* __entry->next_comm, __entry->next_pid, __entry->next_prio),
	372	*
	373	* );
	374	*
	375	* This macro construct is thus used for the regular printk format
	376	* tracing setup, it is used to construct a function pointer based
	377	* tracepoint callback (this is used by programmatic plugins and
	378	* can also by used by generic instrumentation like SystemTap), and
	379	* it is also used to expose a structured trace record in
	380	* /sys/kernel/debug/tracing/events/.
	381	*
	382	* A set of (un)registration functions can be passed to the variant
	383	* TRACE_EVENT_FN to perform any (un)registration work.
	384	*/
	385
	386	#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
	387	#define DEFINE_EVENT(template, name, proto, args) \
	388	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
	389	#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
	390	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
	391	#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
	392	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
	393	#define DEFINE_EVENT_CONDITION(template, name, proto, \
	394	args, cond) \
	395	DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
	396	PARAMS(args), PARAMS(cond))
	397
	398	#define TRACE_EVENT(name, proto, args, struct, assign, print) \
	399	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
	400	#define TRACE_EVENT_FN(name, proto, args, struct, \
	401	assign, print, reg, unreg) \
	402	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
	403	#define TRACE_EVENT_CONDITION(name, proto, args, cond, \
	404	struct, assign, print) \
	405	DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
	406	PARAMS(args), PARAMS(cond))
	407
	408	#define TRACE_EVENT_FLAGS(event, flag)
	409
	410	#define TRACE_EVENT_PERF_PERM(event, expr...)
	411
	412	#endif /* ifdef TRACE_EVENT (see note above) */