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/jump_label.h>
25 struct tracepoint_func {
31 const char *name; /* Tracepoint name */
32 struct jump_label_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) \
125 struct tracepoint_func *it_func_ptr; \
131 rcu_read_lock_sched_notrace(); \
132 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
135 it_func = (it_func_ptr)->func; \
136 __data = (it_func_ptr)->data; \
137 ((void(*)(proto))(it_func))(args); \
138 } while ((++it_func_ptr)->func); \
140 rcu_read_unlock_sched_notrace(); \
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_branch(&__tracepoint_##name.key)) \
153 __DO_TRACE(&__tracepoint_##name, \
154 TP_PROTO(data_proto), \
155 TP_ARGS(data_args), \
156 TP_CONDITION(cond)); \
159 register_trace_##name(void (*probe)(data_proto), void *data) \
161 return tracepoint_probe_register(#name, (void *)probe, \
165 unregister_trace_##name(void (*probe)(data_proto), void *data) \
167 return tracepoint_probe_unregister(#name, (void *)probe, \
171 check_trace_callback_type_##name(void (*cb)(data_proto)) \
176 * We have no guarantee that gcc and the linker won't up-align the tracepoint
177 * structures, so we create an array of pointers that will be used for iteration
178 * on the tracepoints.
180 #define DEFINE_TRACE_FN(name, reg, unreg) \
181 static const char __tpstrtab_##name[] \
182 __attribute__((section("__tracepoints_strings"))) = #name; \
183 struct tracepoint __tracepoint_##name \
184 __attribute__((section("__tracepoints"))) = \
185 { __tpstrtab_##name, JUMP_LABEL_INIT, reg, unreg, NULL };\
186 static struct tracepoint * const __tracepoint_ptr_##name __used \
187 __attribute__((section("__tracepoints_ptrs"))) = \
188 &__tracepoint_##name;
190 #define DEFINE_TRACE(name) \
191 DEFINE_TRACE_FN(name, NULL, NULL);
193 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
194 EXPORT_SYMBOL_GPL(__tracepoint_##name)
195 #define EXPORT_TRACEPOINT_SYMBOL(name) \
196 EXPORT_SYMBOL(__tracepoint_##name)
198 #else /* !CONFIG_TRACEPOINTS */
199 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
200 static inline void trace_##name(proto) \
203 register_trace_##name(void (*probe)(data_proto), \
209 unregister_trace_##name(void (*probe)(data_proto), \
214 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
218 #define DEFINE_TRACE_FN(name, reg, unreg)
219 #define DEFINE_TRACE(name)
220 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
221 #define EXPORT_TRACEPOINT_SYMBOL(name)
223 #endif /* CONFIG_TRACEPOINTS */
226 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
227 * (void). "void" is a special value in a function prototype and can
228 * not be combined with other arguments. Since the DECLARE_TRACE()
229 * macro adds a data element at the beginning of the prototype,
230 * we need a way to differentiate "(void *data, proto)" from
231 * "(void *data, void)". The second prototype is invalid.
233 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
234 * and "void *__data" as the callback prototype.
236 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
237 * "void *__data, proto" as the callback prototype.
239 #define DECLARE_TRACE_NOARGS(name) \
240 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
242 #define DECLARE_TRACE(name, proto, args) \
243 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
244 PARAMS(void *__data, proto), \
245 PARAMS(__data, args))
247 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
248 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
249 PARAMS(void *__data, proto), \
250 PARAMS(__data, args))
252 #define TRACE_EVENT_FLAGS(event, flag)
254 #endif /* DECLARE_TRACE */
258 * For use with the TRACE_EVENT macro:
260 * We define a tracepoint, its arguments, its printk format
261 * and its 'fast binay record' layout.
263 * Firstly, name your tracepoint via TRACE_EVENT(name : the
264 * 'subsystem_event' notation is fine.
266 * Think about this whole construct as the
267 * 'trace_sched_switch() function' from now on.
270 * TRACE_EVENT(sched_switch,
273 * * A function has a regular function arguments
274 * * prototype, declare it via TP_PROTO():
277 * TP_PROTO(struct rq *rq, struct task_struct *prev,
278 * struct task_struct *next),
281 * * Define the call signature of the 'function'.
282 * * (Design sidenote: we use this instead of a
283 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
286 * TP_ARGS(rq, prev, next),
289 * * Fast binary tracing: define the trace record via
290 * * TP_STRUCT__entry(). You can think about it like a
291 * * regular C structure local variable definition.
293 * * This is how the trace record is structured and will
294 * * be saved into the ring buffer. These are the fields
295 * * that will be exposed to user-space in
296 * * /sys/kernel/debug/tracing/events/<*>/format.
298 * * The declared 'local variable' is called '__entry'
300 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
304 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
306 * * char prev_comm[TASK_COMM_LEN];
310 * __array( char, prev_comm, TASK_COMM_LEN )
311 * __field( pid_t, prev_pid )
312 * __field( int, prev_prio )
313 * __array( char, next_comm, TASK_COMM_LEN )
314 * __field( pid_t, next_pid )
315 * __field( int, next_prio )
319 * * Assign the entry into the trace record, by embedding
320 * * a full C statement block into TP_fast_assign(). You
321 * * can refer to the trace record as '__entry' -
322 * * otherwise you can put arbitrary C code in here.
324 * * Note: this C code will execute every time a trace event
325 * * happens, on an active tracepoint.
329 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
330 * __entry->prev_pid = prev->pid;
331 * __entry->prev_prio = prev->prio;
332 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
333 * __entry->next_pid = next->pid;
334 * __entry->next_prio = next->prio;
338 * * Formatted output of a trace record via TP_printk().
339 * * This is how the tracepoint will appear under ftrace
340 * * plugins that make use of this tracepoint.
342 * * (raw-binary tracing wont actually perform this step.)
345 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
346 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
347 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
351 * This macro construct is thus used for the regular printk format
352 * tracing setup, it is used to construct a function pointer based
353 * tracepoint callback (this is used by programmatic plugins and
354 * can also by used by generic instrumentation like SystemTap), and
355 * it is also used to expose a structured trace record in
356 * /sys/kernel/debug/tracing/events/.
358 * A set of (un)registration functions can be passed to the variant
359 * TRACE_EVENT_FN to perform any (un)registration work.
362 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
363 #define DEFINE_EVENT(template, name, proto, args) \
364 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
365 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
366 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
367 #define DEFINE_EVENT_CONDITION(template, name, proto, \
369 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
370 PARAMS(args), PARAMS(cond))
372 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
373 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
374 #define TRACE_EVENT_FN(name, proto, args, struct, \
375 assign, print, reg, unreg) \
376 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
377 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
378 struct, assign, print) \
379 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
380 PARAMS(args), PARAMS(cond))
382 #define TRACE_EVENT_FLAGS(event, flag)
384 #endif /* ifdef TRACE_EVENT (see note above) */