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/tracepoint-defs.h>
26 struct notifier_block
;
28 struct trace_enum_map
{
30 const char *enum_string
;
31 unsigned long enum_value
;
34 #define TRACEPOINT_DEFAULT_PRIO 10
37 tracepoint_probe_register(struct tracepoint
*tp
, void *probe
, void *data
);
39 tracepoint_probe_register_prio(struct tracepoint
*tp
, void *probe
, void *data
,
42 tracepoint_probe_unregister(struct tracepoint
*tp
, void *probe
, void *data
);
44 for_each_kernel_tracepoint(void (*fct
)(struct tracepoint
*tp
, void *priv
),
49 struct list_head list
;
53 bool trace_module_has_bad_taint(struct module
*mod
);
54 extern int register_tracepoint_module_notifier(struct notifier_block
*nb
);
55 extern int unregister_tracepoint_module_notifier(struct notifier_block
*nb
);
57 static inline bool trace_module_has_bad_taint(struct module
*mod
)
62 int register_tracepoint_module_notifier(struct notifier_block
*nb
)
67 int unregister_tracepoint_module_notifier(struct notifier_block
*nb
)
71 #endif /* CONFIG_MODULES */
74 * tracepoint_synchronize_unregister must be called between the last tracepoint
75 * probe unregistration and the end of module exit to make sure there is no
76 * caller executing a probe when it is freed.
78 static inline void tracepoint_synchronize_unregister(void)
83 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
84 extern void syscall_regfunc(void);
85 extern void syscall_unregfunc(void);
86 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
88 #define PARAMS(args...) args
90 #define TRACE_DEFINE_ENUM(x)
92 #endif /* _LINUX_TRACEPOINT_H */
95 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
96 * file ifdef protection.
97 * This is due to the way trace events work. If a file includes two
98 * trace event headers under one "CREATE_TRACE_POINTS" the first include
99 * will override the TRACE_EVENT and break the second include.
102 #ifndef DECLARE_TRACE
104 #define TP_PROTO(args...) args
105 #define TP_ARGS(args...) args
106 #define TP_CONDITION(args...) args
109 * Individual subsystem my have a separate configuration to
110 * enable their tracepoints. By default, this file will create
111 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
112 * wants to be able to disable its tracepoints from being created
113 * it can define NOTRACE before including the tracepoint headers.
115 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
116 #define TRACEPOINTS_ENABLED
119 #ifdef TRACEPOINTS_ENABLED
122 * it_func[0] is never NULL because there is at least one element in the array
123 * when the array itself is non NULL.
125 * Note, the proto and args passed in includes "__data" as the first parameter.
126 * The reason for this is to handle the "void" prototype. If a tracepoint
127 * has a "void" prototype, then it is invalid to declare a function
128 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
129 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
131 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
133 struct tracepoint_func *it_func_ptr; \
137 if (!cpu_online(raw_smp_processor_id())) \
143 rcu_read_lock_sched_notrace(); \
144 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
147 it_func = (it_func_ptr)->func; \
148 __data = (it_func_ptr)->data; \
149 ((void(*)(proto))(it_func))(args); \
150 } while ((++it_func_ptr)->func); \
152 rcu_read_unlock_sched_notrace(); \
157 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
158 static inline void trace_##name##_rcuidle(proto) \
160 if (static_key_false(&__tracepoint_##name.key)) \
161 __DO_TRACE(&__tracepoint_##name, \
162 TP_PROTO(data_proto), \
163 TP_ARGS(data_args), \
164 TP_CONDITION(cond), \
165 rcu_irq_enter_irqson(), \
166 rcu_irq_exit_irqson()); \
169 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
173 * Make sure the alignment of the structure in the __tracepoints section will
174 * not add unwanted padding between the beginning of the section and the
175 * structure. Force alignment to the same alignment as the section start.
177 * When lockdep is enabled, we make sure to always do the RCU portions of
178 * the tracepoint code, regardless of whether tracing is on. However,
179 * don't check if the condition is false, due to interaction with idle
180 * instrumentation. This lets us find RCU issues triggered with tracepoints
181 * even when this tracepoint is off. This code has no purpose other than
184 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
185 extern struct tracepoint __tracepoint_##name; \
186 static inline void trace_##name(proto) \
188 if (static_key_false(&__tracepoint_##name.key)) \
189 __DO_TRACE(&__tracepoint_##name, \
190 TP_PROTO(data_proto), \
191 TP_ARGS(data_args), \
192 TP_CONDITION(cond),,); \
193 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
194 rcu_read_lock_sched_notrace(); \
195 rcu_dereference_sched(__tracepoint_##name.funcs);\
196 rcu_read_unlock_sched_notrace(); \
199 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
200 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
202 register_trace_##name(void (*probe)(data_proto), void *data) \
204 return tracepoint_probe_register(&__tracepoint_##name, \
205 (void *)probe, data); \
208 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
211 return tracepoint_probe_register_prio(&__tracepoint_##name, \
212 (void *)probe, data, prio); \
215 unregister_trace_##name(void (*probe)(data_proto), void *data) \
217 return tracepoint_probe_unregister(&__tracepoint_##name,\
218 (void *)probe, data); \
221 check_trace_callback_type_##name(void (*cb)(data_proto)) \
225 trace_##name##_enabled(void) \
227 return static_key_false(&__tracepoint_##name.key); \
231 * We have no guarantee that gcc and the linker won't up-align the tracepoint
232 * structures, so we create an array of pointers that will be used for iteration
233 * on the tracepoints.
235 #define DEFINE_TRACE_FN(name, reg, unreg) \
236 static const char __tpstrtab_##name[] \
237 __attribute__((section("__tracepoints_strings"))) = #name; \
238 struct tracepoint __tracepoint_##name \
239 __attribute__((section("__tracepoints"))) = \
240 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
241 static struct tracepoint * const __tracepoint_ptr_##name __used \
242 __attribute__((section("__tracepoints_ptrs"))) = \
243 &__tracepoint_##name;
245 #define DEFINE_TRACE(name) \
246 DEFINE_TRACE_FN(name, NULL, NULL);
248 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
249 EXPORT_SYMBOL_GPL(__tracepoint_##name)
250 #define EXPORT_TRACEPOINT_SYMBOL(name) \
251 EXPORT_SYMBOL(__tracepoint_##name)
253 #else /* !TRACEPOINTS_ENABLED */
254 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
255 static inline void trace_##name(proto) \
257 static inline void trace_##name##_rcuidle(proto) \
260 register_trace_##name(void (*probe)(data_proto), \
266 unregister_trace_##name(void (*probe)(data_proto), \
271 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
275 trace_##name##_enabled(void) \
280 #define DEFINE_TRACE_FN(name, reg, unreg)
281 #define DEFINE_TRACE(name)
282 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
283 #define EXPORT_TRACEPOINT_SYMBOL(name)
285 #endif /* TRACEPOINTS_ENABLED */
287 #ifdef CONFIG_TRACING
289 * tracepoint_string - register constant persistent string to trace system
290 * @str - a constant persistent string that will be referenced in tracepoints
292 * If constant strings are being used in tracepoints, it is faster and
293 * more efficient to just save the pointer to the string and reference
294 * that with a printf "%s" instead of saving the string in the ring buffer
295 * and wasting space and time.
297 * The problem with the above approach is that userspace tools that read
298 * the binary output of the trace buffers do not have access to the string.
299 * Instead they just show the address of the string which is not very
302 * With tracepoint_string(), the string will be registered to the tracing
303 * system and exported to userspace via the debugfs/tracing/printk_formats
304 * file that maps the string address to the string text. This way userspace
305 * tools that read the binary buffers have a way to map the pointers to
306 * the ASCII strings they represent.
308 * The @str used must be a constant string and persistent as it would not
309 * make sense to show a string that no longer exists. But it is still fine
310 * to be used with modules, because when modules are unloaded, if they
311 * had tracepoints, the ring buffers are cleared too. As long as the string
312 * does not change during the life of the module, it is fine to use
313 * tracepoint_string() within a module.
315 #define tracepoint_string(str) \
317 static const char *___tp_str __tracepoint_string = str; \
320 #define __tracepoint_string __attribute__((section("__tracepoint_str")))
323 * tracepoint_string() is used to save the string address for userspace
324 * tracing tools. When tracing isn't configured, there's no need to save
327 # define tracepoint_string(str) str
328 # define __tracepoint_string
332 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
333 * (void). "void" is a special value in a function prototype and can
334 * not be combined with other arguments. Since the DECLARE_TRACE()
335 * macro adds a data element at the beginning of the prototype,
336 * we need a way to differentiate "(void *data, proto)" from
337 * "(void *data, void)". The second prototype is invalid.
339 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
340 * and "void *__data" as the callback prototype.
342 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
343 * "void *__data, proto" as the callback prototype.
345 #define DECLARE_TRACE_NOARGS(name) \
346 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
348 #define DECLARE_TRACE(name, proto, args) \
349 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
350 PARAMS(void *__data, proto), \
351 PARAMS(__data, args))
353 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
354 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
355 PARAMS(void *__data, proto), \
356 PARAMS(__data, args))
358 #define TRACE_EVENT_FLAGS(event, flag)
360 #define TRACE_EVENT_PERF_PERM(event, expr...)
362 #endif /* DECLARE_TRACE */
366 * For use with the TRACE_EVENT macro:
368 * We define a tracepoint, its arguments, its printk format
369 * and its 'fast binary record' layout.
371 * Firstly, name your tracepoint via TRACE_EVENT(name : the
372 * 'subsystem_event' notation is fine.
374 * Think about this whole construct as the
375 * 'trace_sched_switch() function' from now on.
378 * TRACE_EVENT(sched_switch,
381 * * A function has a regular function arguments
382 * * prototype, declare it via TP_PROTO():
385 * TP_PROTO(struct rq *rq, struct task_struct *prev,
386 * struct task_struct *next),
389 * * Define the call signature of the 'function'.
390 * * (Design sidenote: we use this instead of a
391 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
394 * TP_ARGS(rq, prev, next),
397 * * Fast binary tracing: define the trace record via
398 * * TP_STRUCT__entry(). You can think about it like a
399 * * regular C structure local variable definition.
401 * * This is how the trace record is structured and will
402 * * be saved into the ring buffer. These are the fields
403 * * that will be exposed to user-space in
404 * * /sys/kernel/debug/tracing/events/<*>/format.
406 * * The declared 'local variable' is called '__entry'
408 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
412 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
414 * * char prev_comm[TASK_COMM_LEN];
418 * __array( char, prev_comm, TASK_COMM_LEN )
419 * __field( pid_t, prev_pid )
420 * __field( int, prev_prio )
421 * __array( char, next_comm, TASK_COMM_LEN )
422 * __field( pid_t, next_pid )
423 * __field( int, next_prio )
427 * * Assign the entry into the trace record, by embedding
428 * * a full C statement block into TP_fast_assign(). You
429 * * can refer to the trace record as '__entry' -
430 * * otherwise you can put arbitrary C code in here.
432 * * Note: this C code will execute every time a trace event
433 * * happens, on an active tracepoint.
437 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
438 * __entry->prev_pid = prev->pid;
439 * __entry->prev_prio = prev->prio;
440 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
441 * __entry->next_pid = next->pid;
442 * __entry->next_prio = next->prio;
446 * * Formatted output of a trace record via TP_printk().
447 * * This is how the tracepoint will appear under ftrace
448 * * plugins that make use of this tracepoint.
450 * * (raw-binary tracing wont actually perform this step.)
453 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
454 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
455 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
459 * This macro construct is thus used for the regular printk format
460 * tracing setup, it is used to construct a function pointer based
461 * tracepoint callback (this is used by programmatic plugins and
462 * can also by used by generic instrumentation like SystemTap), and
463 * it is also used to expose a structured trace record in
464 * /sys/kernel/debug/tracing/events/.
466 * A set of (un)registration functions can be passed to the variant
467 * TRACE_EVENT_FN to perform any (un)registration work.
470 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
471 #define DEFINE_EVENT(template, name, proto, args) \
472 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
473 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
474 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
475 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
476 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
477 #define DEFINE_EVENT_CONDITION(template, name, proto, \
479 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
480 PARAMS(args), PARAMS(cond))
482 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
483 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
484 #define TRACE_EVENT_FN(name, proto, args, struct, \
485 assign, print, reg, unreg) \
486 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
487 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
488 assign, print, reg, unreg) \
489 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
490 PARAMS(args), PARAMS(cond))
491 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
492 struct, assign, print) \
493 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
494 PARAMS(args), PARAMS(cond))
496 #define TRACE_EVENT_FLAGS(event, flag)
498 #define TRACE_EVENT_PERF_PERM(event, expr...)
500 #endif /* ifdef TRACE_EVENT (see note above) */
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