1 #ifndef _LINUX_TRACEPOINT_H
2 #define _LINUX_TRACEPOINT_H
5 * Kernel Tracepoint API.
7 * See Documentation/trace/tracepoints.txt.
9 * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
11 * Heavily inspired from the Linux Kernel Markers.
13 * This file is released under the GPLv2.
14 * See the file COPYING for more details.
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/rcupdate.h>
20 #include <linux/static_key.h>
25 struct tracepoint_func
{
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
;
39 * Connect a probe to a tracepoint.
40 * Internal API, should not be used directly.
42 extern int tracepoint_probe_register(const char *name
, void *probe
, void *data
);
45 * Disconnect a probe from a tracepoint.
46 * Internal API, should not be used directly.
49 tracepoint_probe_unregister(const char *name
, void *probe
, void *data
);
51 extern int tracepoint_probe_register_noupdate(const char *name
, void *probe
,
53 extern int tracepoint_probe_unregister_noupdate(const char *name
, void *probe
,
55 extern void tracepoint_probe_update_all(void);
59 struct list_head list
;
60 unsigned int num_tracepoints
;
61 struct tracepoint
* const *tracepoints_ptrs
;
63 #endif /* CONFIG_MODULES */
65 struct tracepoint_iter
{
67 struct tp_module
*module
;
68 #endif /* CONFIG_MODULES */
69 struct tracepoint
* const *tracepoint
;
72 extern void tracepoint_iter_start(struct tracepoint_iter
*iter
);
73 extern void tracepoint_iter_next(struct tracepoint_iter
*iter
);
74 extern void tracepoint_iter_stop(struct tracepoint_iter
*iter
);
75 extern void tracepoint_iter_reset(struct tracepoint_iter
*iter
);
78 * tracepoint_synchronize_unregister must be called between the last tracepoint
79 * probe unregistration and the end of module exit to make sure there is no
80 * caller executing a probe when it is freed.
82 static inline void tracepoint_synchronize_unregister(void)
87 #define PARAMS(args...) args
89 #endif /* _LINUX_TRACEPOINT_H */
92 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
93 * file ifdef protection.
94 * This is due to the way trace events work. If a file includes two
95 * trace event headers under one "CREATE_TRACE_POINTS" the first include
96 * will override the TRACE_EVENT and break the second include.
101 #define TP_PROTO(args...) args
102 #define TP_ARGS(args...) args
103 #define TP_CONDITION(args...) args
105 #ifdef CONFIG_TRACEPOINTS
108 * it_func[0] is never NULL because there is at least one element in the array
109 * when the array itself is non NULL.
111 * Note, the proto and args passed in includes "__data" as the first parameter.
112 * The reason for this is to handle the "void" prototype. If a tracepoint
113 * has a "void" prototype, then it is invalid to declare a function
114 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
115 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
117 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
119 struct tracepoint_func *it_func_ptr; \
126 rcu_read_lock_sched_notrace(); \
127 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
130 it_func = (it_func_ptr)->func; \
131 __data = (it_func_ptr)->data; \
132 ((void(*)(proto))(it_func))(args); \
133 } while ((++it_func_ptr)->func); \
135 rcu_read_unlock_sched_notrace(); \
140 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
141 static inline void trace_##name##_rcuidle(proto) \
143 if (static_key_false(&__tracepoint_##name.key)) \
144 __DO_TRACE(&__tracepoint_##name, \
145 TP_PROTO(data_proto), \
146 TP_ARGS(data_args), \
147 TP_CONDITION(cond), \
152 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
156 * Make sure the alignment of the structure in the __tracepoints section will
157 * not add unwanted padding between the beginning of the section and the
158 * structure. Force alignment to the same alignment as the section start.
160 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
161 extern struct tracepoint __tracepoint_##name; \
162 static inline void trace_##name(proto) \
164 if (static_key_false(&__tracepoint_##name.key)) \
165 __DO_TRACE(&__tracepoint_##name, \
166 TP_PROTO(data_proto), \
167 TP_ARGS(data_args), \
168 TP_CONDITION(cond),,); \
170 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
171 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
173 register_trace_##name(void (*probe)(data_proto), void *data) \
175 return tracepoint_probe_register(#name, (void *)probe, \
179 unregister_trace_##name(void (*probe)(data_proto), void *data) \
181 return tracepoint_probe_unregister(#name, (void *)probe, \
185 check_trace_callback_type_##name(void (*cb)(data_proto)) \
190 * We have no guarantee that gcc and the linker won't up-align the tracepoint
191 * structures, so we create an array of pointers that will be used for iteration
192 * on the tracepoints.
194 #define DEFINE_TRACE_FN(name, reg, unreg) \
195 static const char __tpstrtab_##name[] \
196 __attribute__((section("__tracepoints_strings"))) = #name; \
197 struct tracepoint __tracepoint_##name \
198 __attribute__((section("__tracepoints"))) = \
199 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
200 static struct tracepoint * const __tracepoint_ptr_##name __used \
201 __attribute__((section("__tracepoints_ptrs"))) = \
202 &__tracepoint_##name;
204 #define DEFINE_TRACE(name) \
205 DEFINE_TRACE_FN(name, NULL, NULL);
207 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
208 EXPORT_SYMBOL_GPL(__tracepoint_##name)
209 #define EXPORT_TRACEPOINT_SYMBOL(name) \
210 EXPORT_SYMBOL(__tracepoint_##name)
212 #else /* !CONFIG_TRACEPOINTS */
213 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
214 static inline void trace_##name(proto) \
216 static inline void trace_##name##_rcuidle(proto) \
219 register_trace_##name(void (*probe)(data_proto), \
225 unregister_trace_##name(void (*probe)(data_proto), \
230 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
234 #define DEFINE_TRACE_FN(name, reg, unreg)
235 #define DEFINE_TRACE(name)
236 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
237 #define EXPORT_TRACEPOINT_SYMBOL(name)
239 #endif /* CONFIG_TRACEPOINTS */
242 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
243 * (void). "void" is a special value in a function prototype and can
244 * not be combined with other arguments. Since the DECLARE_TRACE()
245 * macro adds a data element at the beginning of the prototype,
246 * we need a way to differentiate "(void *data, proto)" from
247 * "(void *data, void)". The second prototype is invalid.
249 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
250 * and "void *__data" as the callback prototype.
252 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
253 * "void *__data, proto" as the callback prototype.
255 #define DECLARE_TRACE_NOARGS(name) \
256 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
258 #define DECLARE_TRACE(name, proto, args) \
259 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
260 PARAMS(void *__data, proto), \
261 PARAMS(__data, args))
263 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
264 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
265 PARAMS(void *__data, proto), \
266 PARAMS(__data, args))
268 #define TRACE_EVENT_FLAGS(event, flag)
270 #endif /* DECLARE_TRACE */
274 * For use with the TRACE_EVENT macro:
276 * We define a tracepoint, its arguments, its printk format
277 * and its 'fast binay record' layout.
279 * Firstly, name your tracepoint via TRACE_EVENT(name : the
280 * 'subsystem_event' notation is fine.
282 * Think about this whole construct as the
283 * 'trace_sched_switch() function' from now on.
286 * TRACE_EVENT(sched_switch,
289 * * A function has a regular function arguments
290 * * prototype, declare it via TP_PROTO():
293 * TP_PROTO(struct rq *rq, struct task_struct *prev,
294 * struct task_struct *next),
297 * * Define the call signature of the 'function'.
298 * * (Design sidenote: we use this instead of a
299 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
302 * TP_ARGS(rq, prev, next),
305 * * Fast binary tracing: define the trace record via
306 * * TP_STRUCT__entry(). You can think about it like a
307 * * regular C structure local variable definition.
309 * * This is how the trace record is structured and will
310 * * be saved into the ring buffer. These are the fields
311 * * that will be exposed to user-space in
312 * * /sys/kernel/debug/tracing/events/<*>/format.
314 * * The declared 'local variable' is called '__entry'
316 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
320 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
322 * * char prev_comm[TASK_COMM_LEN];
326 * __array( char, prev_comm, TASK_COMM_LEN )
327 * __field( pid_t, prev_pid )
328 * __field( int, prev_prio )
329 * __array( char, next_comm, TASK_COMM_LEN )
330 * __field( pid_t, next_pid )
331 * __field( int, next_prio )
335 * * Assign the entry into the trace record, by embedding
336 * * a full C statement block into TP_fast_assign(). You
337 * * can refer to the trace record as '__entry' -
338 * * otherwise you can put arbitrary C code in here.
340 * * Note: this C code will execute every time a trace event
341 * * happens, on an active tracepoint.
345 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
346 * __entry->prev_pid = prev->pid;
347 * __entry->prev_prio = prev->prio;
348 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
349 * __entry->next_pid = next->pid;
350 * __entry->next_prio = next->prio;
354 * * Formatted output of a trace record via TP_printk().
355 * * This is how the tracepoint will appear under ftrace
356 * * plugins that make use of this tracepoint.
358 * * (raw-binary tracing wont actually perform this step.)
361 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
362 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
363 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
367 * This macro construct is thus used for the regular printk format
368 * tracing setup, it is used to construct a function pointer based
369 * tracepoint callback (this is used by programmatic plugins and
370 * can also by used by generic instrumentation like SystemTap), and
371 * it is also used to expose a structured trace record in
372 * /sys/kernel/debug/tracing/events/.
374 * A set of (un)registration functions can be passed to the variant
375 * TRACE_EVENT_FN to perform any (un)registration work.
378 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
379 #define DEFINE_EVENT(template, name, proto, args) \
380 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
381 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
382 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
383 #define DEFINE_EVENT_CONDITION(template, name, proto, \
385 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
386 PARAMS(args), PARAMS(cond))
388 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
389 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
390 #define TRACE_EVENT_FN(name, proto, args, struct, \
391 assign, print, reg, unreg) \
392 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
393 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
394 struct, assign, print) \
395 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
396 PARAMS(args), PARAMS(cond))
398 #define TRACE_EVENT_FLAGS(event, flag)
400 #endif /* ifdef TRACE_EVENT (see note above) */
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