1 #ifndef _LINUX_TRACEPOINT_H
2 #define _LINUX_TRACEPOINT_H
5 * Kernel Tracepoint API.
7 * See Documentation/trace/tracepoints.txt.
9 * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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>
24 struct notifier_block;
26 struct tracepoint_func {
33 const char *name; /* Tracepoint name */
34 struct static_key key;
35 void (*regfunc)(void);
36 void (*unregfunc)(void);
37 struct tracepoint_func __rcu *funcs;
40 struct trace_enum_map {
42 const char *enum_string;
43 unsigned long enum_value;
46 #define TRACEPOINT_DEFAULT_PRIO 10
49 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
51 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
54 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
56 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
61 struct list_head list;
65 bool trace_module_has_bad_taint(struct module *mod);
66 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
67 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
69 static inline bool trace_module_has_bad_taint(struct module *mod)
74 int register_tracepoint_module_notifier(struct notifier_block *nb)
79 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
83 #endif /* CONFIG_MODULES */
86 * tracepoint_synchronize_unregister must be called between the last tracepoint
87 * probe unregistration and the end of module exit to make sure there is no
88 * caller executing a probe when it is freed.
90 static inline void tracepoint_synchronize_unregister(void)
95 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
96 extern void syscall_regfunc(void);
97 extern void syscall_unregfunc(void);
98 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
100 #define PARAMS(args...) args
102 #define TRACE_DEFINE_ENUM(x)
104 #endif /* _LINUX_TRACEPOINT_H */
107 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
108 * file ifdef protection.
109 * This is due to the way trace events work. If a file includes two
110 * trace event headers under one "CREATE_TRACE_POINTS" the first include
111 * will override the TRACE_EVENT and break the second include.
114 #ifndef DECLARE_TRACE
116 #define TP_PROTO(args...) args
117 #define TP_ARGS(args...) args
118 #define TP_CONDITION(args...) args
121 * Individual subsystem my have a separate configuration to
122 * enable their tracepoints. By default, this file will create
123 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
124 * wants to be able to disable its tracepoints from being created
125 * it can define NOTRACE before including the tracepoint headers.
127 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
128 #define TRACEPOINTS_ENABLED
131 #ifdef TRACEPOINTS_ENABLED
134 * it_func[0] is never NULL because there is at least one element in the array
135 * when the array itself is non NULL.
137 * Note, the proto and args passed in includes "__data" as the first parameter.
138 * The reason for this is to handle the "void" prototype. If a tracepoint
139 * has a "void" prototype, then it is invalid to declare a function
140 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
141 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
143 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
145 struct tracepoint_func *it_func_ptr; \
152 rcu_read_lock_sched_notrace(); \
153 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
156 it_func = (it_func_ptr)->func; \
157 __data = (it_func_ptr)->data; \
158 ((void(*)(proto))(it_func))(args); \
159 } while ((++it_func_ptr)->func); \
161 rcu_read_unlock_sched_notrace(); \
166 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
167 static inline void trace_##name##_rcuidle(proto) \
169 if (static_key_false(&__tracepoint_##name.key)) \
170 __DO_TRACE(&__tracepoint_##name, \
171 TP_PROTO(data_proto), \
172 TP_ARGS(data_args), \
173 TP_CONDITION(cond), \
178 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
182 * Make sure the alignment of the structure in the __tracepoints section will
183 * not add unwanted padding between the beginning of the section and the
184 * structure. Force alignment to the same alignment as the section start.
186 * When lockdep is enabled, we make sure to always do the RCU portions of
187 * the tracepoint code, regardless of whether tracing is on or we match the
188 * condition. This lets us find RCU issues triggered with tracepoints even
189 * when this tracepoint is off. This code has no purpose other than poking
192 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
193 extern struct tracepoint __tracepoint_##name; \
194 static inline void trace_##name(proto) \
196 if (static_key_false(&__tracepoint_##name.key)) \
197 __DO_TRACE(&__tracepoint_##name, \
198 TP_PROTO(data_proto), \
199 TP_ARGS(data_args), \
200 TP_CONDITION(cond),,); \
201 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
202 rcu_read_lock_sched_notrace(); \
203 rcu_dereference_sched(__tracepoint_##name.funcs);\
204 rcu_read_unlock_sched_notrace(); \
207 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
208 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
210 register_trace_##name(void (*probe)(data_proto), void *data) \
212 return tracepoint_probe_register(&__tracepoint_##name, \
213 (void *)probe, data); \
216 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
219 return tracepoint_probe_register_prio(&__tracepoint_##name, \
220 (void *)probe, data, prio); \
223 unregister_trace_##name(void (*probe)(data_proto), void *data) \
225 return tracepoint_probe_unregister(&__tracepoint_##name,\
226 (void *)probe, data); \
229 check_trace_callback_type_##name(void (*cb)(data_proto)) \
233 trace_##name##_enabled(void) \
235 return static_key_false(&__tracepoint_##name.key); \
239 * We have no guarantee that gcc and the linker won't up-align the tracepoint
240 * structures, so we create an array of pointers that will be used for iteration
241 * on the tracepoints.
243 #define DEFINE_TRACE_FN(name, reg, unreg) \
244 static const char __tpstrtab_##name[] \
245 __attribute__((section("__tracepoints_strings"))) = #name; \
246 struct tracepoint __tracepoint_##name \
247 __attribute__((section("__tracepoints"))) = \
248 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
249 static struct tracepoint * const __tracepoint_ptr_##name __used \
250 __attribute__((section("__tracepoints_ptrs"))) = \
251 &__tracepoint_##name;
253 #define DEFINE_TRACE(name) \
254 DEFINE_TRACE_FN(name, NULL, NULL);
256 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
257 EXPORT_SYMBOL_GPL(__tracepoint_##name)
258 #define EXPORT_TRACEPOINT_SYMBOL(name) \
259 EXPORT_SYMBOL(__tracepoint_##name)
261 #else /* !TRACEPOINTS_ENABLED */
262 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
263 static inline void trace_##name(proto) \
265 static inline void trace_##name##_rcuidle(proto) \
268 register_trace_##name(void (*probe)(data_proto), \
274 unregister_trace_##name(void (*probe)(data_proto), \
279 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
283 trace_##name##_enabled(void) \
288 #define DEFINE_TRACE_FN(name, reg, unreg)
289 #define DEFINE_TRACE(name)
290 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
291 #define EXPORT_TRACEPOINT_SYMBOL(name)
293 #endif /* TRACEPOINTS_ENABLED */
295 #ifdef CONFIG_TRACING
297 * tracepoint_string - register constant persistent string to trace system
298 * @str - a constant persistent string that will be referenced in tracepoints
300 * If constant strings are being used in tracepoints, it is faster and
301 * more efficient to just save the pointer to the string and reference
302 * that with a printf "%s" instead of saving the string in the ring buffer
303 * and wasting space and time.
305 * The problem with the above approach is that userspace tools that read
306 * the binary output of the trace buffers do not have access to the string.
307 * Instead they just show the address of the string which is not very
310 * With tracepoint_string(), the string will be registered to the tracing
311 * system and exported to userspace via the debugfs/tracing/printk_formats
312 * file that maps the string address to the string text. This way userspace
313 * tools that read the binary buffers have a way to map the pointers to
314 * the ASCII strings they represent.
316 * The @str used must be a constant string and persistent as it would not
317 * make sense to show a string that no longer exists. But it is still fine
318 * to be used with modules, because when modules are unloaded, if they
319 * had tracepoints, the ring buffers are cleared too. As long as the string
320 * does not change during the life of the module, it is fine to use
321 * tracepoint_string() within a module.
323 #define tracepoint_string(str) \
325 static const char *___tp_str __tracepoint_string = str; \
328 #define __tracepoint_string __attribute__((section("__tracepoint_str")))
331 * tracepoint_string() is used to save the string address for userspace
332 * tracing tools. When tracing isn't configured, there's no need to save
335 # define tracepoint_string(str) str
336 # define __tracepoint_string
340 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
341 * (void). "void" is a special value in a function prototype and can
342 * not be combined with other arguments. Since the DECLARE_TRACE()
343 * macro adds a data element at the beginning of the prototype,
344 * we need a way to differentiate "(void *data, proto)" from
345 * "(void *data, void)". The second prototype is invalid.
347 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
348 * and "void *__data" as the callback prototype.
350 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
351 * "void *__data, proto" as the callback prototype.
353 #define DECLARE_TRACE_NOARGS(name) \
354 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
356 #define DECLARE_TRACE(name, proto, args) \
357 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
358 PARAMS(void *__data, proto), \
359 PARAMS(__data, args))
361 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
362 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
363 PARAMS(void *__data, proto), \
364 PARAMS(__data, args))
366 #define TRACE_EVENT_FLAGS(event, flag)
368 #define TRACE_EVENT_PERF_PERM(event, expr...)
370 #endif /* DECLARE_TRACE */
374 * For use with the TRACE_EVENT macro:
376 * We define a tracepoint, its arguments, its printk format
377 * and its 'fast binary record' layout.
379 * Firstly, name your tracepoint via TRACE_EVENT(name : the
380 * 'subsystem_event' notation is fine.
382 * Think about this whole construct as the
383 * 'trace_sched_switch() function' from now on.
386 * TRACE_EVENT(sched_switch,
389 * * A function has a regular function arguments
390 * * prototype, declare it via TP_PROTO():
393 * TP_PROTO(struct rq *rq, struct task_struct *prev,
394 * struct task_struct *next),
397 * * Define the call signature of the 'function'.
398 * * (Design sidenote: we use this instead of a
399 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
402 * TP_ARGS(rq, prev, next),
405 * * Fast binary tracing: define the trace record via
406 * * TP_STRUCT__entry(). You can think about it like a
407 * * regular C structure local variable definition.
409 * * This is how the trace record is structured and will
410 * * be saved into the ring buffer. These are the fields
411 * * that will be exposed to user-space in
412 * * /sys/kernel/debug/tracing/events/<*>/format.
414 * * The declared 'local variable' is called '__entry'
416 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
420 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
422 * * char prev_comm[TASK_COMM_LEN];
426 * __array( char, prev_comm, TASK_COMM_LEN )
427 * __field( pid_t, prev_pid )
428 * __field( int, prev_prio )
429 * __array( char, next_comm, TASK_COMM_LEN )
430 * __field( pid_t, next_pid )
431 * __field( int, next_prio )
435 * * Assign the entry into the trace record, by embedding
436 * * a full C statement block into TP_fast_assign(). You
437 * * can refer to the trace record as '__entry' -
438 * * otherwise you can put arbitrary C code in here.
440 * * Note: this C code will execute every time a trace event
441 * * happens, on an active tracepoint.
445 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
446 * __entry->prev_pid = prev->pid;
447 * __entry->prev_prio = prev->prio;
448 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
449 * __entry->next_pid = next->pid;
450 * __entry->next_prio = next->prio;
454 * * Formatted output of a trace record via TP_printk().
455 * * This is how the tracepoint will appear under ftrace
456 * * plugins that make use of this tracepoint.
458 * * (raw-binary tracing wont actually perform this step.)
461 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
462 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
463 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
467 * This macro construct is thus used for the regular printk format
468 * tracing setup, it is used to construct a function pointer based
469 * tracepoint callback (this is used by programmatic plugins and
470 * can also by used by generic instrumentation like SystemTap), and
471 * it is also used to expose a structured trace record in
472 * /sys/kernel/debug/tracing/events/.
474 * A set of (un)registration functions can be passed to the variant
475 * TRACE_EVENT_FN to perform any (un)registration work.
478 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
479 #define DEFINE_EVENT(template, name, proto, args) \
480 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
481 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
482 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
483 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
484 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
485 #define DEFINE_EVENT_CONDITION(template, name, proto, \
487 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
488 PARAMS(args), PARAMS(cond))
490 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
491 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
492 #define TRACE_EVENT_FN(name, proto, args, struct, \
493 assign, print, reg, unreg) \
494 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
495 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
496 struct, assign, print) \
497 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
498 PARAMS(args), PARAMS(cond))
500 #define TRACE_EVENT_FLAGS(event, flag)
502 #define TRACE_EVENT_PERF_PERM(event, expr...)
504 #endif /* ifdef TRACE_EVENT (see note above) */