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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
);
53 struct list_head list
;
54 unsigned int num_tracepoints
;
55 struct tracepoint
* const *tracepoints_ptrs
;
57 bool trace_module_has_bad_taint(struct module
*mod
);
59 static inline bool trace_module_has_bad_taint(struct module
*mod
)
63 #endif /* CONFIG_MODULES */
66 * tracepoint_synchronize_unregister must be called between the last tracepoint
67 * probe unregistration and the end of module exit to make sure there is no
68 * caller executing a probe when it is freed.
70 static inline void tracepoint_synchronize_unregister(void)
75 #define PARAMS(args...) args
77 #endif /* _LINUX_TRACEPOINT_H */
80 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
81 * file ifdef protection.
82 * This is due to the way trace events work. If a file includes two
83 * trace event headers under one "CREATE_TRACE_POINTS" the first include
84 * will override the TRACE_EVENT and break the second include.
89 #define TP_PROTO(args...) args
90 #define TP_ARGS(args...) args
91 #define TP_CONDITION(args...) args
93 #ifdef CONFIG_TRACEPOINTS
96 * it_func[0] is never NULL because there is at least one element in the array
97 * when the array itself is non NULL.
99 * Note, the proto and args passed in includes "__data" as the first parameter.
100 * The reason for this is to handle the "void" prototype. If a tracepoint
101 * has a "void" prototype, then it is invalid to declare a function
102 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
103 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
105 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
107 struct tracepoint_func *it_func_ptr; \
114 rcu_read_lock_sched_notrace(); \
115 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
118 it_func = (it_func_ptr)->func; \
119 __data = (it_func_ptr)->data; \
120 ((void(*)(proto))(it_func))(args); \
121 } while ((++it_func_ptr)->func); \
123 rcu_read_unlock_sched_notrace(); \
128 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
129 static inline void trace_##name##_rcuidle(proto) \
131 if (static_key_false(&__tracepoint_##name.key)) \
132 __DO_TRACE(&__tracepoint_##name, \
133 TP_PROTO(data_proto), \
134 TP_ARGS(data_args), \
135 TP_CONDITION(cond), \
140 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
144 * Make sure the alignment of the structure in the __tracepoints section will
145 * not add unwanted padding between the beginning of the section and the
146 * structure. Force alignment to the same alignment as the section start.
148 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
149 extern struct tracepoint __tracepoint_##name; \
150 static inline void trace_##name(proto) \
152 if (static_key_false(&__tracepoint_##name.key)) \
153 __DO_TRACE(&__tracepoint_##name, \
154 TP_PROTO(data_proto), \
155 TP_ARGS(data_args), \
156 TP_CONDITION(cond),,); \
158 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
159 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
161 register_trace_##name(void (*probe)(data_proto), void *data) \
163 return tracepoint_probe_register(#name, (void *)probe, \
167 unregister_trace_##name(void (*probe)(data_proto), void *data) \
169 return tracepoint_probe_unregister(#name, (void *)probe, \
173 check_trace_callback_type_##name(void (*cb)(data_proto)) \
178 * We have no guarantee that gcc and the linker won't up-align the tracepoint
179 * structures, so we create an array of pointers that will be used for iteration
180 * on the tracepoints.
182 #define DEFINE_TRACE_FN(name, reg, unreg) \
183 static const char __tpstrtab_##name[] \
184 __attribute__((section("__tracepoints_strings"))) = #name; \
185 struct tracepoint __tracepoint_##name \
186 __attribute__((section("__tracepoints"))) = \
187 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
188 static struct tracepoint * const __tracepoint_ptr_##name __used \
189 __attribute__((section("__tracepoints_ptrs"))) = \
190 &__tracepoint_##name;
192 #define DEFINE_TRACE(name) \
193 DEFINE_TRACE_FN(name, NULL, NULL);
195 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
196 EXPORT_SYMBOL_GPL(__tracepoint_##name)
197 #define EXPORT_TRACEPOINT_SYMBOL(name) \
198 EXPORT_SYMBOL(__tracepoint_##name)
200 #else /* !CONFIG_TRACEPOINTS */
201 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
202 static inline void trace_##name(proto) \
204 static inline void trace_##name##_rcuidle(proto) \
207 register_trace_##name(void (*probe)(data_proto), \
213 unregister_trace_##name(void (*probe)(data_proto), \
218 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
222 #define DEFINE_TRACE_FN(name, reg, unreg)
223 #define DEFINE_TRACE(name)
224 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
225 #define EXPORT_TRACEPOINT_SYMBOL(name)
227 #endif /* CONFIG_TRACEPOINTS */
230 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
231 * (void). "void" is a special value in a function prototype and can
232 * not be combined with other arguments. Since the DECLARE_TRACE()
233 * macro adds a data element at the beginning of the prototype,
234 * we need a way to differentiate "(void *data, proto)" from
235 * "(void *data, void)". The second prototype is invalid.
237 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
238 * and "void *__data" as the callback prototype.
240 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
241 * "void *__data, proto" as the callback prototype.
243 #define DECLARE_TRACE_NOARGS(name) \
244 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
246 #define DECLARE_TRACE(name, proto, args) \
247 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
248 PARAMS(void *__data, proto), \
249 PARAMS(__data, args))
251 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
252 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
253 PARAMS(void *__data, proto), \
254 PARAMS(__data, args))
256 #define TRACE_EVENT_FLAGS(event, flag)
258 #define TRACE_EVENT_PERF_PERM(event, expr...)
260 #endif /* DECLARE_TRACE */
264 * For use with the TRACE_EVENT macro:
266 * We define a tracepoint, its arguments, its printk format
267 * and its 'fast binary record' layout.
269 * Firstly, name your tracepoint via TRACE_EVENT(name : the
270 * 'subsystem_event' notation is fine.
272 * Think about this whole construct as the
273 * 'trace_sched_switch() function' from now on.
276 * TRACE_EVENT(sched_switch,
279 * * A function has a regular function arguments
280 * * prototype, declare it via TP_PROTO():
283 * TP_PROTO(struct rq *rq, struct task_struct *prev,
284 * struct task_struct *next),
287 * * Define the call signature of the 'function'.
288 * * (Design sidenote: we use this instead of a
289 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
292 * TP_ARGS(rq, prev, next),
295 * * Fast binary tracing: define the trace record via
296 * * TP_STRUCT__entry(). You can think about it like a
297 * * regular C structure local variable definition.
299 * * This is how the trace record is structured and will
300 * * be saved into the ring buffer. These are the fields
301 * * that will be exposed to user-space in
302 * * /sys/kernel/debug/tracing/events/<*>/format.
304 * * The declared 'local variable' is called '__entry'
306 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
310 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
312 * * char prev_comm[TASK_COMM_LEN];
316 * __array( char, prev_comm, TASK_COMM_LEN )
317 * __field( pid_t, prev_pid )
318 * __field( int, prev_prio )
319 * __array( char, next_comm, TASK_COMM_LEN )
320 * __field( pid_t, next_pid )
321 * __field( int, next_prio )
325 * * Assign the entry into the trace record, by embedding
326 * * a full C statement block into TP_fast_assign(). You
327 * * can refer to the trace record as '__entry' -
328 * * otherwise you can put arbitrary C code in here.
330 * * Note: this C code will execute every time a trace event
331 * * happens, on an active tracepoint.
335 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
336 * __entry->prev_pid = prev->pid;
337 * __entry->prev_prio = prev->prio;
338 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
339 * __entry->next_pid = next->pid;
340 * __entry->next_prio = next->prio;
344 * * Formatted output of a trace record via TP_printk().
345 * * This is how the tracepoint will appear under ftrace
346 * * plugins that make use of this tracepoint.
348 * * (raw-binary tracing wont actually perform this step.)
351 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
352 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
353 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
357 * This macro construct is thus used for the regular printk format
358 * tracing setup, it is used to construct a function pointer based
359 * tracepoint callback (this is used by programmatic plugins and
360 * can also by used by generic instrumentation like SystemTap), and
361 * it is also used to expose a structured trace record in
362 * /sys/kernel/debug/tracing/events/.
364 * A set of (un)registration functions can be passed to the variant
365 * TRACE_EVENT_FN to perform any (un)registration work.
368 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
369 #define DEFINE_EVENT(template, name, proto, args) \
370 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
371 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
372 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
373 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
374 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
375 #define DEFINE_EVENT_CONDITION(template, name, proto, \
377 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
378 PARAMS(args), PARAMS(cond))
380 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
381 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
382 #define TRACE_EVENT_FN(name, proto, args, struct, \
383 assign, print, reg, unreg) \
384 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
385 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
386 struct, assign, print) \
387 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
388 PARAMS(args), PARAMS(cond))
390 #define TRACE_EVENT_FLAGS(event, flag)
392 #define TRACE_EVENT_PERF_PERM(event, expr...)
394 #endif /* ifdef TRACE_EVENT (see note above) */