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/smp.h>
18 #include <linux/errno.h>
19 #include <linux/types.h>
20 #include <linux/cpumask.h>
21 #include <linux/rcupdate.h>
22 #include <linux/static_key.h>
26 struct notifier_block;
28 struct tracepoint_func {
35 const char *name; /* Tracepoint name */
36 struct static_key key;
37 void (*regfunc)(void);
38 void (*unregfunc)(void);
39 struct tracepoint_func __rcu *funcs;
42 struct trace_enum_map {
44 const char *enum_string;
45 unsigned long enum_value;
48 #define TRACEPOINT_DEFAULT_PRIO 10
51 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
53 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
56 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
58 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
63 struct list_head list;
67 bool trace_module_has_bad_taint(struct module *mod);
68 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
69 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
71 static inline bool trace_module_has_bad_taint(struct module *mod)
76 int register_tracepoint_module_notifier(struct notifier_block *nb)
81 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
85 #endif /* CONFIG_MODULES */
88 * tracepoint_synchronize_unregister must be called between the last tracepoint
89 * probe unregistration and the end of module exit to make sure there is no
90 * caller executing a probe when it is freed.
92 static inline void tracepoint_synchronize_unregister(void)
97 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
98 extern void syscall_regfunc(void);
99 extern void syscall_unregfunc(void);
100 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
102 #define PARAMS(args...) args
104 #define TRACE_DEFINE_ENUM(x)
106 #endif /* _LINUX_TRACEPOINT_H */
109 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
110 * file ifdef protection.
111 * This is due to the way trace events work. If a file includes two
112 * trace event headers under one "CREATE_TRACE_POINTS" the first include
113 * will override the TRACE_EVENT and break the second include.
116 #ifndef DECLARE_TRACE
118 #define TP_PROTO(args...) args
119 #define TP_ARGS(args...) args
120 #define TP_CONDITION(args...) args
123 * Individual subsystem my have a separate configuration to
124 * enable their tracepoints. By default, this file will create
125 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
126 * wants to be able to disable its tracepoints from being created
127 * it can define NOTRACE before including the tracepoint headers.
129 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
130 #define TRACEPOINTS_ENABLED
133 #ifdef TRACEPOINTS_ENABLED
136 * it_func[0] is never NULL because there is at least one element in the array
137 * when the array itself is non NULL.
139 * Note, the proto and args passed in includes "__data" as the first parameter.
140 * The reason for this is to handle the "void" prototype. If a tracepoint
141 * has a "void" prototype, then it is invalid to declare a function
142 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
143 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
145 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
147 struct tracepoint_func *it_func_ptr; \
151 if (!cpu_online(raw_smp_processor_id())) \
157 rcu_read_lock_sched_notrace(); \
158 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
161 it_func = (it_func_ptr)->func; \
162 __data = (it_func_ptr)->data; \
163 ((void(*)(proto))(it_func))(args); \
164 } while ((++it_func_ptr)->func); \
166 rcu_read_unlock_sched_notrace(); \
171 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
172 static inline void trace_##name##_rcuidle(proto) \
174 if (static_key_false(&__tracepoint_##name.key)) \
175 __DO_TRACE(&__tracepoint_##name, \
176 TP_PROTO(data_proto), \
177 TP_ARGS(data_args), \
178 TP_CONDITION(cond), \
183 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
187 * Make sure the alignment of the structure in the __tracepoints section will
188 * not add unwanted padding between the beginning of the section and the
189 * structure. Force alignment to the same alignment as the section start.
191 * When lockdep is enabled, we make sure to always do the RCU portions of
192 * the tracepoint code, regardless of whether tracing is on. However,
193 * don't check if the condition is false, due to interaction with idle
194 * instrumentation. This lets us find RCU issues triggered with tracepoints
195 * even when this tracepoint is off. This code has no purpose other than
198 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
199 extern struct tracepoint __tracepoint_##name; \
200 static inline void trace_##name(proto) \
202 if (static_key_false(&__tracepoint_##name.key)) \
203 __DO_TRACE(&__tracepoint_##name, \
204 TP_PROTO(data_proto), \
205 TP_ARGS(data_args), \
206 TP_CONDITION(cond),,); \
207 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
208 rcu_read_lock_sched_notrace(); \
209 rcu_dereference_sched(__tracepoint_##name.funcs);\
210 rcu_read_unlock_sched_notrace(); \
213 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
214 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
216 register_trace_##name(void (*probe)(data_proto), void *data) \
218 return tracepoint_probe_register(&__tracepoint_##name, \
219 (void *)probe, data); \
222 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
225 return tracepoint_probe_register_prio(&__tracepoint_##name, \
226 (void *)probe, data, prio); \
229 unregister_trace_##name(void (*probe)(data_proto), void *data) \
231 return tracepoint_probe_unregister(&__tracepoint_##name,\
232 (void *)probe, data); \
235 check_trace_callback_type_##name(void (*cb)(data_proto)) \
239 trace_##name##_enabled(void) \
241 return static_key_false(&__tracepoint_##name.key); \
245 * We have no guarantee that gcc and the linker won't up-align the tracepoint
246 * structures, so we create an array of pointers that will be used for iteration
247 * on the tracepoints.
249 #define DEFINE_TRACE_FN(name, reg, unreg) \
250 static const char __tpstrtab_##name[] \
251 __attribute__((section("__tracepoints_strings"))) = #name; \
252 struct tracepoint __tracepoint_##name \
253 __attribute__((section("__tracepoints"))) = \
254 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
255 static struct tracepoint * const __tracepoint_ptr_##name __used \
256 __attribute__((section("__tracepoints_ptrs"))) = \
257 &__tracepoint_##name;
259 #define DEFINE_TRACE(name) \
260 DEFINE_TRACE_FN(name, NULL, NULL);
262 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
263 EXPORT_SYMBOL_GPL(__tracepoint_##name)
264 #define EXPORT_TRACEPOINT_SYMBOL(name) \
265 EXPORT_SYMBOL(__tracepoint_##name)
267 #else /* !TRACEPOINTS_ENABLED */
268 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
269 static inline void trace_##name(proto) \
271 static inline void trace_##name##_rcuidle(proto) \
274 register_trace_##name(void (*probe)(data_proto), \
280 unregister_trace_##name(void (*probe)(data_proto), \
285 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
289 trace_##name##_enabled(void) \
294 #define DEFINE_TRACE_FN(name, reg, unreg)
295 #define DEFINE_TRACE(name)
296 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
297 #define EXPORT_TRACEPOINT_SYMBOL(name)
299 #endif /* TRACEPOINTS_ENABLED */
301 #ifdef CONFIG_TRACING
303 * tracepoint_string - register constant persistent string to trace system
304 * @str - a constant persistent string that will be referenced in tracepoints
306 * If constant strings are being used in tracepoints, it is faster and
307 * more efficient to just save the pointer to the string and reference
308 * that with a printf "%s" instead of saving the string in the ring buffer
309 * and wasting space and time.
311 * The problem with the above approach is that userspace tools that read
312 * the binary output of the trace buffers do not have access to the string.
313 * Instead they just show the address of the string which is not very
316 * With tracepoint_string(), the string will be registered to the tracing
317 * system and exported to userspace via the debugfs/tracing/printk_formats
318 * file that maps the string address to the string text. This way userspace
319 * tools that read the binary buffers have a way to map the pointers to
320 * the ASCII strings they represent.
322 * The @str used must be a constant string and persistent as it would not
323 * make sense to show a string that no longer exists. But it is still fine
324 * to be used with modules, because when modules are unloaded, if they
325 * had tracepoints, the ring buffers are cleared too. As long as the string
326 * does not change during the life of the module, it is fine to use
327 * tracepoint_string() within a module.
329 #define tracepoint_string(str) \
331 static const char *___tp_str __tracepoint_string = str; \
334 #define __tracepoint_string __attribute__((section("__tracepoint_str")))
337 * tracepoint_string() is used to save the string address for userspace
338 * tracing tools. When tracing isn't configured, there's no need to save
341 # define tracepoint_string(str) str
342 # define __tracepoint_string
346 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
347 * (void). "void" is a special value in a function prototype and can
348 * not be combined with other arguments. Since the DECLARE_TRACE()
349 * macro adds a data element at the beginning of the prototype,
350 * we need a way to differentiate "(void *data, proto)" from
351 * "(void *data, void)". The second prototype is invalid.
353 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
354 * and "void *__data" as the callback prototype.
356 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
357 * "void *__data, proto" as the callback prototype.
359 #define DECLARE_TRACE_NOARGS(name) \
360 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
362 #define DECLARE_TRACE(name, proto, args) \
363 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
364 PARAMS(void *__data, proto), \
365 PARAMS(__data, args))
367 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
368 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
369 PARAMS(void *__data, proto), \
370 PARAMS(__data, args))
372 #define TRACE_EVENT_FLAGS(event, flag)
374 #define TRACE_EVENT_PERF_PERM(event, expr...)
376 #endif /* DECLARE_TRACE */
380 * For use with the TRACE_EVENT macro:
382 * We define a tracepoint, its arguments, its printk format
383 * and its 'fast binary record' layout.
385 * Firstly, name your tracepoint via TRACE_EVENT(name : the
386 * 'subsystem_event' notation is fine.
388 * Think about this whole construct as the
389 * 'trace_sched_switch() function' from now on.
392 * TRACE_EVENT(sched_switch,
395 * * A function has a regular function arguments
396 * * prototype, declare it via TP_PROTO():
399 * TP_PROTO(struct rq *rq, struct task_struct *prev,
400 * struct task_struct *next),
403 * * Define the call signature of the 'function'.
404 * * (Design sidenote: we use this instead of a
405 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
408 * TP_ARGS(rq, prev, next),
411 * * Fast binary tracing: define the trace record via
412 * * TP_STRUCT__entry(). You can think about it like a
413 * * regular C structure local variable definition.
415 * * This is how the trace record is structured and will
416 * * be saved into the ring buffer. These are the fields
417 * * that will be exposed to user-space in
418 * * /sys/kernel/debug/tracing/events/<*>/format.
420 * * The declared 'local variable' is called '__entry'
422 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
426 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
428 * * char prev_comm[TASK_COMM_LEN];
432 * __array( char, prev_comm, TASK_COMM_LEN )
433 * __field( pid_t, prev_pid )
434 * __field( int, prev_prio )
435 * __array( char, next_comm, TASK_COMM_LEN )
436 * __field( pid_t, next_pid )
437 * __field( int, next_prio )
441 * * Assign the entry into the trace record, by embedding
442 * * a full C statement block into TP_fast_assign(). You
443 * * can refer to the trace record as '__entry' -
444 * * otherwise you can put arbitrary C code in here.
446 * * Note: this C code will execute every time a trace event
447 * * happens, on an active tracepoint.
451 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
452 * __entry->prev_pid = prev->pid;
453 * __entry->prev_prio = prev->prio;
454 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
455 * __entry->next_pid = next->pid;
456 * __entry->next_prio = next->prio;
460 * * Formatted output of a trace record via TP_printk().
461 * * This is how the tracepoint will appear under ftrace
462 * * plugins that make use of this tracepoint.
464 * * (raw-binary tracing wont actually perform this step.)
467 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
468 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
469 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
473 * This macro construct is thus used for the regular printk format
474 * tracing setup, it is used to construct a function pointer based
475 * tracepoint callback (this is used by programmatic plugins and
476 * can also by used by generic instrumentation like SystemTap), and
477 * it is also used to expose a structured trace record in
478 * /sys/kernel/debug/tracing/events/.
480 * A set of (un)registration functions can be passed to the variant
481 * TRACE_EVENT_FN to perform any (un)registration work.
484 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
485 #define DEFINE_EVENT(template, name, proto, args) \
486 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
487 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
488 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
489 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
490 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
491 #define DEFINE_EVENT_CONDITION(template, name, proto, \
493 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
494 PARAMS(args), PARAMS(cond))
496 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
497 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
498 #define TRACE_EVENT_FN(name, proto, args, struct, \
499 assign, print, reg, unreg) \
500 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
501 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
502 struct, assign, print) \
503 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
504 PARAMS(args), PARAMS(cond))
506 #define TRACE_EVENT_FLAGS(event, flag)
508 #define TRACE_EVENT_PERF_PERM(event, expr...)
510 #endif /* ifdef TRACE_EVENT (see note above) */