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 bool trace_module_has_bad_taint(struct module *mod);
65 static inline bool trace_module_has_bad_taint(struct module *mod)
69 #endif /* CONFIG_MODULES */
71 struct tracepoint_iter {
73 struct tp_module *module;
74 #endif /* CONFIG_MODULES */
75 struct tracepoint * const *tracepoint;
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);
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.
88 static inline void tracepoint_synchronize_unregister(void)
93 #define PARAMS(args...) args
95 #endif /* _LINUX_TRACEPOINT_H */
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.
105 #ifndef DECLARE_TRACE
107 #define TP_PROTO(args...) args
108 #define TP_ARGS(args...) args
109 #define TP_CONDITION(args...) args
111 #ifdef CONFIG_TRACEPOINTS
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.
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".
123 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
125 struct tracepoint_func *it_func_ptr; \
132 rcu_read_lock_sched_notrace(); \
133 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
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); \
141 rcu_read_unlock_sched_notrace(); \
146 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
147 static inline void trace_##name##_rcuidle(proto) \
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), \
158 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
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.
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) \
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),,); \
176 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
177 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
179 register_trace_##name(void (*probe)(data_proto), void *data) \
181 return tracepoint_probe_register(#name, (void *)probe, \
185 unregister_trace_##name(void (*probe)(data_proto), void *data) \
187 return tracepoint_probe_unregister(#name, (void *)probe, \
191 check_trace_callback_type_##name(void (*cb)(data_proto)) \
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.
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;
210 #define DEFINE_TRACE(name) \
211 DEFINE_TRACE_FN(name, NULL, NULL);
213 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
214 EXPORT_SYMBOL_GPL(__tracepoint_##name)
215 #define EXPORT_TRACEPOINT_SYMBOL(name) \
216 EXPORT_SYMBOL(__tracepoint_##name)
218 #else /* !CONFIG_TRACEPOINTS */
219 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
220 static inline void trace_##name(proto) \
222 static inline void trace_##name##_rcuidle(proto) \
225 register_trace_##name(void (*probe)(data_proto), \
231 unregister_trace_##name(void (*probe)(data_proto), \
236 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
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)
245 #endif /* CONFIG_TRACEPOINTS */
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.
255 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
256 * and "void *__data" as the callback prototype.
258 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
259 * "void *__data, proto" as the callback prototype.
261 #define DECLARE_TRACE_NOARGS(name) \
262 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
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))
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))
274 #define TRACE_EVENT_FLAGS(event, flag)
276 #endif /* DECLARE_TRACE */
280 * For use with the TRACE_EVENT macro:
282 * We define a tracepoint, its arguments, its printk format
283 * and its 'fast binay record' layout.
285 * Firstly, name your tracepoint via TRACE_EVENT(name : the
286 * 'subsystem_event' notation is fine.
288 * Think about this whole construct as the
289 * 'trace_sched_switch() function' from now on.
292 * TRACE_EVENT(sched_switch,
295 * * A function has a regular function arguments
296 * * prototype, declare it via TP_PROTO():
299 * TP_PROTO(struct rq *rq, struct task_struct *prev,
300 * struct task_struct *next),
303 * * Define the call signature of the 'function'.
304 * * (Design sidenote: we use this instead of a
305 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
308 * TP_ARGS(rq, prev, next),
311 * * Fast binary tracing: define the trace record via
312 * * TP_STRUCT__entry(). You can think about it like a
313 * * regular C structure local variable definition.
315 * * This is how the trace record is structured and will
316 * * be saved into the ring buffer. These are the fields
317 * * that will be exposed to user-space in
318 * * /sys/kernel/debug/tracing/events/<*>/format.
320 * * The declared 'local variable' is called '__entry'
322 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
326 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
328 * * char prev_comm[TASK_COMM_LEN];
332 * __array( char, prev_comm, TASK_COMM_LEN )
333 * __field( pid_t, prev_pid )
334 * __field( int, prev_prio )
335 * __array( char, next_comm, TASK_COMM_LEN )
336 * __field( pid_t, next_pid )
337 * __field( int, next_prio )
341 * * Assign the entry into the trace record, by embedding
342 * * a full C statement block into TP_fast_assign(). You
343 * * can refer to the trace record as '__entry' -
344 * * otherwise you can put arbitrary C code in here.
346 * * Note: this C code will execute every time a trace event
347 * * happens, on an active tracepoint.
351 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
352 * __entry->prev_pid = prev->pid;
353 * __entry->prev_prio = prev->prio;
354 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
355 * __entry->next_pid = next->pid;
356 * __entry->next_prio = next->prio;
360 * * Formatted output of a trace record via TP_printk().
361 * * This is how the tracepoint will appear under ftrace
362 * * plugins that make use of this tracepoint.
364 * * (raw-binary tracing wont actually perform this step.)
367 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
368 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
369 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
373 * This macro construct is thus used for the regular printk format
374 * tracing setup, it is used to construct a function pointer based
375 * tracepoint callback (this is used by programmatic plugins and
376 * can also by used by generic instrumentation like SystemTap), and
377 * it is also used to expose a structured trace record in
378 * /sys/kernel/debug/tracing/events/.
380 * A set of (un)registration functions can be passed to the variant
381 * TRACE_EVENT_FN to perform any (un)registration work.
384 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
385 #define DEFINE_EVENT(template, name, proto, args) \
386 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
387 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
388 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
389 #define DEFINE_EVENT_CONDITION(template, name, proto, \
391 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
392 PARAMS(args), PARAMS(cond))
394 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
395 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
396 #define TRACE_EVENT_FN(name, proto, args, struct, \
397 assign, print, reg, unreg) \
398 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
399 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
400 struct, assign, print) \
401 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
402 PARAMS(args), PARAMS(cond))
404 #define TRACE_EVENT_FLAGS(event, flag)
406 #endif /* ifdef TRACE_EVENT (see note above) */