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 #endif /* CONFIG_MODULES */
64
65 struct tracepoint_iter {
66 #ifdef CONFIG_MODULES
67 struct tp_module *module;
68 #endif /* CONFIG_MODULES */
69 struct tracepoint * const *tracepoint;
70 };
71
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);
76
77 /*
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.
81 */
tracepoint_synchronize_unregister(void)82 static inline void tracepoint_synchronize_unregister(void)
83 {
84 synchronize_sched();
85 }
86
87 #define PARAMS(args...) args
88
89 #endif /* _LINUX_TRACEPOINT_H */
90
91 /*
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.
97 */
98
99 #ifndef DECLARE_TRACE
100
101 #define TP_PROTO(args...) args
102 #define TP_ARGS(args...) args
103 #define TP_CONDITION(args...) args
104
105 #ifdef CONFIG_TRACEPOINTS
106
107 /*
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.
110 *
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".
116 */
117 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
118 do { \
119 struct tracepoint_func *it_func_ptr; \
120 void *it_func; \
121 void *__data; \
122 \
123 if (!(cond)) \
124 return; \
125 prercu; \
126 rcu_read_lock_sched_notrace(); \
127 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
128 if (it_func_ptr) { \
129 do { \
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); \
134 } \
135 rcu_read_unlock_sched_notrace(); \
136 postrcu; \
137 } while (0)
138
139 /*
140 * Make sure the alignment of the structure in the __tracepoints section will
141 * not add unwanted padding between the beginning of the section and the
142 * structure. Force alignment to the same alignment as the section start.
143 */
144 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
145 extern struct tracepoint __tracepoint_##name; \
146 static inline void trace_##name(proto) \
147 { \
148 if (static_key_false(&__tracepoint_##name.key)) \
149 __DO_TRACE(&__tracepoint_##name, \
150 TP_PROTO(data_proto), \
151 TP_ARGS(data_args), \
152 TP_CONDITION(cond),,); \
153 } \
154 static inline void trace_##name##_rcuidle(proto) \
155 { \
156 if (static_branch(&__tracepoint_##name.key)) \
157 __DO_TRACE(&__tracepoint_##name, \
158 TP_PROTO(data_proto), \
159 TP_ARGS(data_args), \
160 TP_CONDITION(cond), \
161 rcu_idle_exit(), \
162 rcu_idle_enter()); \
163 } \
164 static inline int \
165 register_trace_##name(void (*probe)(data_proto), void *data) \
166 { \
167 return tracepoint_probe_register(#name, (void *)probe, \
168 data); \
169 } \
170 static inline int \
171 unregister_trace_##name(void (*probe)(data_proto), void *data) \
172 { \
173 return tracepoint_probe_unregister(#name, (void *)probe, \
174 data); \
175 } \
176 static inline void \
177 check_trace_callback_type_##name(void (*cb)(data_proto)) \
178 { \
179 }
180
181 /*
182 * We have no guarantee that gcc and the linker won't up-align the tracepoint
183 * structures, so we create an array of pointers that will be used for iteration
184 * on the tracepoints.
185 */
186 #define DEFINE_TRACE_FN(name, reg, unreg) \
187 static const char __tpstrtab_##name[] \
188 __attribute__((section("__tracepoints_strings"))) = #name; \
189 struct tracepoint __tracepoint_##name \
190 __attribute__((section("__tracepoints"))) = \
191 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
192 static struct tracepoint * const __tracepoint_ptr_##name __used \
193 __attribute__((section("__tracepoints_ptrs"))) = \
194 &__tracepoint_##name;
195
196 #define DEFINE_TRACE(name) \
197 DEFINE_TRACE_FN(name, NULL, NULL);
198
199 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
200 EXPORT_SYMBOL_GPL(__tracepoint_##name)
201 #define EXPORT_TRACEPOINT_SYMBOL(name) \
202 EXPORT_SYMBOL(__tracepoint_##name)
203
204 #else /* !CONFIG_TRACEPOINTS */
205 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
206 static inline void trace_##name(proto) \
207 { } \
208 static inline void trace_##name##_rcuidle(proto) \
209 { } \
210 static inline int \
211 register_trace_##name(void (*probe)(data_proto), \
212 void *data) \
213 { \
214 return -ENOSYS; \
215 } \
216 static inline int \
217 unregister_trace_##name(void (*probe)(data_proto), \
218 void *data) \
219 { \
220 return -ENOSYS; \
221 } \
222 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
223 { \
224 }
225
226 #define DEFINE_TRACE_FN(name, reg, unreg)
227 #define DEFINE_TRACE(name)
228 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
229 #define EXPORT_TRACEPOINT_SYMBOL(name)
230
231 #endif /* CONFIG_TRACEPOINTS */
232
233 /*
234 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
235 * (void). "void" is a special value in a function prototype and can
236 * not be combined with other arguments. Since the DECLARE_TRACE()
237 * macro adds a data element at the beginning of the prototype,
238 * we need a way to differentiate "(void *data, proto)" from
239 * "(void *data, void)". The second prototype is invalid.
240 *
241 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
242 * and "void *__data" as the callback prototype.
243 *
244 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
245 * "void *__data, proto" as the callback prototype.
246 */
247 #define DECLARE_TRACE_NOARGS(name) \
248 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
249
250 #define DECLARE_TRACE(name, proto, args) \
251 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
252 PARAMS(void *__data, proto), \
253 PARAMS(__data, args))
254
255 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
256 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
257 PARAMS(void *__data, proto), \
258 PARAMS(__data, args))
259
260 #define TRACE_EVENT_FLAGS(event, flag)
261
262 #endif /* DECLARE_TRACE */
263
264 #ifndef TRACE_EVENT
265 /*
266 * For use with the TRACE_EVENT macro:
267 *
268 * We define a tracepoint, its arguments, its printk format
269 * and its 'fast binay record' layout.
270 *
271 * Firstly, name your tracepoint via TRACE_EVENT(name : the
272 * 'subsystem_event' notation is fine.
273 *
274 * Think about this whole construct as the
275 * 'trace_sched_switch() function' from now on.
276 *
277 *
278 * TRACE_EVENT(sched_switch,
279 *
280 * *
281 * * A function has a regular function arguments
282 * * prototype, declare it via TP_PROTO():
283 * *
284 *
285 * TP_PROTO(struct rq *rq, struct task_struct *prev,
286 * struct task_struct *next),
287 *
288 * *
289 * * Define the call signature of the 'function'.
290 * * (Design sidenote: we use this instead of a
291 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
292 * *
293 *
294 * TP_ARGS(rq, prev, next),
295 *
296 * *
297 * * Fast binary tracing: define the trace record via
298 * * TP_STRUCT__entry(). You can think about it like a
299 * * regular C structure local variable definition.
300 * *
301 * * This is how the trace record is structured and will
302 * * be saved into the ring buffer. These are the fields
303 * * that will be exposed to user-space in
304 * * /sys/kernel/debug/tracing/events/<*>/format.
305 * *
306 * * The declared 'local variable' is called '__entry'
307 * *
308 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
309 * *
310 * * pid_t prev_pid;
311 * *
312 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
313 * *
314 * * char prev_comm[TASK_COMM_LEN];
315 * *
316 *
317 * TP_STRUCT__entry(
318 * __array( char, prev_comm, TASK_COMM_LEN )
319 * __field( pid_t, prev_pid )
320 * __field( int, prev_prio )
321 * __array( char, next_comm, TASK_COMM_LEN )
322 * __field( pid_t, next_pid )
323 * __field( int, next_prio )
324 * ),
325 *
326 * *
327 * * Assign the entry into the trace record, by embedding
328 * * a full C statement block into TP_fast_assign(). You
329 * * can refer to the trace record as '__entry' -
330 * * otherwise you can put arbitrary C code in here.
331 * *
332 * * Note: this C code will execute every time a trace event
333 * * happens, on an active tracepoint.
334 * *
335 *
336 * TP_fast_assign(
337 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
338 * __entry->prev_pid = prev->pid;
339 * __entry->prev_prio = prev->prio;
340 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
341 * __entry->next_pid = next->pid;
342 * __entry->next_prio = next->prio;
343 * ),
344 *
345 * *
346 * * Formatted output of a trace record via TP_printk().
347 * * This is how the tracepoint will appear under ftrace
348 * * plugins that make use of this tracepoint.
349 * *
350 * * (raw-binary tracing wont actually perform this step.)
351 * *
352 *
353 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
354 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
355 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
356 *
357 * );
358 *
359 * This macro construct is thus used for the regular printk format
360 * tracing setup, it is used to construct a function pointer based
361 * tracepoint callback (this is used by programmatic plugins and
362 * can also by used by generic instrumentation like SystemTap), and
363 * it is also used to expose a structured trace record in
364 * /sys/kernel/debug/tracing/events/.
365 *
366 * A set of (un)registration functions can be passed to the variant
367 * TRACE_EVENT_FN to perform any (un)registration work.
368 */
369
370 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
371 #define DEFINE_EVENT(template, name, proto, args) \
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, \
376 args, cond) \
377 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
378 PARAMS(args), PARAMS(cond))
379
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))
389
390 #define TRACE_EVENT_FLAGS(event, flag)
391
392 #endif /* ifdef TRACE_EVENT (see note above) */
393