1 /* SPDX-License-Identifier: GPL-2.0-only */
2 #ifndef _LINUX_TRACEPOINT_H
3 #define _LINUX_TRACEPOINT_H
4
5 /*
6 * Kernel Tracepoint API.
7 *
8 * See Documentation/trace/tracepoints.rst.
9 *
10 * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
11 *
12 * Heavily inspired from the Linux Kernel Markers.
13 */
14
15 #include <linux/smp.h>
16 #include <linux/srcu.h>
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/rcupdate.h>
20 #include <linux/rcupdate_trace.h>
21 #include <linux/tracepoint-defs.h>
22 #include <linux/static_call.h>
23
24 struct module;
25 struct tracepoint;
26 struct notifier_block;
27
28 struct trace_eval_map {
29 const char *system;
30 const char *eval_string;
31 unsigned long eval_value;
32 };
33
34 #define TRACEPOINT_DEFAULT_PRIO 10
35
36 extern int
37 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
38 extern int
39 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
40 int prio);
41 extern int
42 tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe, void *data,
43 int prio);
44 extern int
45 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
46 static inline int
tracepoint_probe_register_may_exist(struct tracepoint * tp,void * probe,void * data)47 tracepoint_probe_register_may_exist(struct tracepoint *tp, void *probe,
48 void *data)
49 {
50 return tracepoint_probe_register_prio_may_exist(tp, probe, data,
51 TRACEPOINT_DEFAULT_PRIO);
52 }
53 extern void
54 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
55 void *priv);
56
57 #ifdef CONFIG_MODULES
58 struct tp_module {
59 struct list_head list;
60 struct module *mod;
61 };
62
63 bool trace_module_has_bad_taint(struct module *mod);
64 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
65 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
66 void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
67 struct module *, void *),
68 void *priv);
69 void for_each_tracepoint_in_module(struct module *,
70 void (*fct)(struct tracepoint *,
71 struct module *, void *),
72 void *priv);
73 #else
trace_module_has_bad_taint(struct module * mod)74 static inline bool trace_module_has_bad_taint(struct module *mod)
75 {
76 return false;
77 }
78 static inline
register_tracepoint_module_notifier(struct notifier_block * nb)79 int register_tracepoint_module_notifier(struct notifier_block *nb)
80 {
81 return 0;
82 }
83 static inline
unregister_tracepoint_module_notifier(struct notifier_block * nb)84 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
85 {
86 return 0;
87 }
88 static inline
for_each_module_tracepoint(void (* fct)(struct tracepoint *,struct module *,void *),void * priv)89 void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
90 struct module *, void *),
91 void *priv)
92 {
93 }
94 static inline
for_each_tracepoint_in_module(struct module * mod,void (* fct)(struct tracepoint *,struct module *,void *),void * priv)95 void for_each_tracepoint_in_module(struct module *mod,
96 void (*fct)(struct tracepoint *,
97 struct module *, void *),
98 void *priv)
99 {
100 }
101 #endif /* CONFIG_MODULES */
102
103 /*
104 * tracepoint_synchronize_unregister must be called between the last tracepoint
105 * probe unregistration and the end of module exit to make sure there is no
106 * caller executing a probe when it is freed.
107 *
108 * An alternative is to use the following for batch reclaim associated
109 * with a given tracepoint:
110 *
111 * - tracepoint_is_faultable() == false: call_srcu()
112 * - tracepoint_is_faultable() == true: call_rcu_tasks_trace()
113 */
114 #ifdef CONFIG_TRACEPOINTS
115 extern struct srcu_struct tracepoint_srcu;
tracepoint_synchronize_unregister(void)116 static inline void tracepoint_synchronize_unregister(void)
117 {
118 synchronize_rcu_tasks_trace();
119 synchronize_srcu(&tracepoint_srcu);
120 }
tracepoint_is_faultable(struct tracepoint * tp)121 static inline bool tracepoint_is_faultable(struct tracepoint *tp)
122 {
123 return tp->ext && tp->ext->faultable;
124 }
125 /*
126 * Run RCU callback with the appropriate grace period wait for non-faultable
127 * tracepoints, e.g., those used in atomic context.
128 */
call_tracepoint_unregister_atomic(struct rcu_head * rcu,rcu_callback_t func)129 static inline void call_tracepoint_unregister_atomic(struct rcu_head *rcu, rcu_callback_t func)
130 {
131 call_srcu(&tracepoint_srcu, rcu, func);
132 }
133 /*
134 * Run RCU callback with the appropriate grace period wait for faultable
135 * tracepoints, e.g., those used in syscall context.
136 */
call_tracepoint_unregister_syscall(struct rcu_head * rcu,rcu_callback_t func)137 static inline void call_tracepoint_unregister_syscall(struct rcu_head *rcu, rcu_callback_t func)
138 {
139 call_rcu_tasks_trace(rcu, func);
140 }
141 #else
tracepoint_synchronize_unregister(void)142 static inline void tracepoint_synchronize_unregister(void)
143 { }
tracepoint_is_faultable(struct tracepoint * tp)144 static inline bool tracepoint_is_faultable(struct tracepoint *tp)
145 {
146 return false;
147 }
call_tracepoint_unregister_atomic(struct rcu_head * rcu,rcu_callback_t func)148 static inline void call_tracepoint_unregister_atomic(struct rcu_head *rcu, rcu_callback_t func)
149 { }
call_tracepoint_unregister_syscall(struct rcu_head * rcu,rcu_callback_t func)150 static inline void call_tracepoint_unregister_syscall(struct rcu_head *rcu, rcu_callback_t func)
151 { }
152 #endif
153
154 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
155 extern int syscall_regfunc(void);
156 extern void syscall_unregfunc(void);
157 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
158
159 #ifndef PARAMS
160 #define PARAMS(args...) args
161 #endif
162
163 #define TRACE_DEFINE_ENUM(x)
164 #define TRACE_DEFINE_SIZEOF(x)
165
166 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
tracepoint_ptr_deref(tracepoint_ptr_t * p)167 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
168 {
169 return offset_to_ptr(p);
170 }
171
172 #define __TRACEPOINT_ENTRY(name) \
173 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \
174 " .balign 4 \n" \
175 " .long __tracepoint_" #name " - . \n" \
176 " .previous \n")
177 #else
tracepoint_ptr_deref(tracepoint_ptr_t * p)178 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
179 {
180 return *p;
181 }
182
183 #define __TRACEPOINT_ENTRY(name) \
184 static tracepoint_ptr_t __tracepoint_ptr_##name __used \
185 __section("__tracepoints_ptrs") = &__tracepoint_##name
186 #endif
187
188 #endif /* _LINUX_TRACEPOINT_H */
189
190 /*
191 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
192 * file ifdef protection.
193 * This is due to the way trace events work. If a file includes two
194 * trace event headers under one "CREATE_TRACE_POINTS" the first include
195 * will override the TRACE_EVENT and break the second include.
196 */
197
198 #ifndef DECLARE_TRACE
199
200 #define TP_PROTO(args...) args
201 #define TP_ARGS(args...) args
202 #define TP_CONDITION(args...) args
203
204 /*
205 * Individual subsystem my have a separate configuration to
206 * enable their tracepoints. By default, this file will create
207 * the tracepoints if CONFIG_TRACEPOINTS is defined. If a subsystem
208 * wants to be able to disable its tracepoints from being created
209 * it can define NOTRACE before including the tracepoint headers.
210 */
211 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
212 #define TRACEPOINTS_ENABLED
213 #endif
214
215 #ifdef TRACEPOINTS_ENABLED
216
217 #ifdef CONFIG_HAVE_STATIC_CALL
218 #define __DO_TRACE_CALL(name, args) \
219 do { \
220 struct tracepoint_func *it_func_ptr; \
221 void *__data; \
222 it_func_ptr = \
223 rcu_dereference_raw((&__tracepoint_##name)->funcs); \
224 if (it_func_ptr) { \
225 __data = (it_func_ptr)->data; \
226 static_call(tp_func_##name)(__data, args); \
227 } \
228 } while (0)
229 #else
230 #define __DO_TRACE_CALL(name, args) __traceiter_##name(NULL, args)
231 #endif /* CONFIG_HAVE_STATIC_CALL */
232
233 /*
234 * Declare an exported function that Rust code can call to trigger this
235 * tracepoint. This function does not include the static branch; that is done
236 * in Rust to avoid a function call when the tracepoint is disabled.
237 */
238 #define DEFINE_RUST_DO_TRACE(name, proto, args)
239 #define __DEFINE_RUST_DO_TRACE(name, proto, args) \
240 notrace void rust_do_trace_##name(proto) \
241 { \
242 __do_trace_##name(args); \
243 }
244
245 /*
246 * When a tracepoint is used, it's name is added to the __tracepoint_check
247 * section. This section is only used at build time to make sure all
248 * defined tracepoints are used. It is discarded after the build.
249 */
250 # define TRACEPOINT_CHECK(name) \
251 static const char __used __section("__tracepoint_check") \
252 __trace_check_##name[] = #name;
253
254 /*
255 * Make sure the alignment of the structure in the __tracepoints section will
256 * not add unwanted padding between the beginning of the section and the
257 * structure. Force alignment to the same alignment as the section start.
258 *
259 * When lockdep is enabled, we make sure to always test if RCU is
260 * "watching" regardless if the tracepoint is enabled or not. Tracepoints
261 * require RCU to be active, and it should always warn at the tracepoint
262 * site if it is not watching, as it will need to be active when the
263 * tracepoint is enabled.
264 */
265 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto) \
266 extern int __traceiter_##name(data_proto); \
267 DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name); \
268 extern struct tracepoint __tracepoint_##name; \
269 extern void rust_do_trace_##name(proto); \
270 static inline int \
271 register_trace_##name(void (*probe)(data_proto), void *data) \
272 { \
273 return tracepoint_probe_register(&__tracepoint_##name, \
274 (void *)probe, data); \
275 } \
276 static inline int \
277 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
278 int prio) \
279 { \
280 return tracepoint_probe_register_prio(&__tracepoint_##name, \
281 (void *)probe, data, prio); \
282 } \
283 static inline int \
284 unregister_trace_##name(void (*probe)(data_proto), void *data) \
285 { \
286 return tracepoint_probe_unregister(&__tracepoint_##name,\
287 (void *)probe, data); \
288 } \
289 static inline void \
290 check_trace_callback_type_##name(void (*cb)(data_proto)) \
291 { \
292 } \
293 static inline bool \
294 trace_##name##_enabled(void) \
295 { \
296 return static_branch_unlikely(&__tracepoint_##name.key);\
297 }
298
299 #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
300 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
301 static inline void __do_trace_##name(proto) \
302 { \
303 TRACEPOINT_CHECK(name) \
304 if (cond) { \
305 guard(srcu_fast_notrace)(&tracepoint_srcu); \
306 __DO_TRACE_CALL(name, TP_ARGS(args)); \
307 } \
308 } \
309 static inline void trace_##name(proto) \
310 { \
311 if (static_branch_unlikely(&__tracepoint_##name.key)) \
312 __do_trace_##name(args); \
313 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
314 WARN_ONCE(!rcu_is_watching(), \
315 "RCU not watching for tracepoint"); \
316 } \
317 } \
318 static inline void trace_call__##name(proto) \
319 { \
320 __do_trace_##name(args); \
321 }
322
323 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto) \
324 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
325 static inline void __do_trace_##name(proto) \
326 { \
327 TRACEPOINT_CHECK(name) \
328 guard(rcu_tasks_trace)(); \
329 __DO_TRACE_CALL(name, TP_ARGS(args)); \
330 } \
331 static inline void trace_##name(proto) \
332 { \
333 might_fault(); \
334 if (static_branch_unlikely(&__tracepoint_##name.key)) \
335 __do_trace_##name(args); \
336 if (IS_ENABLED(CONFIG_LOCKDEP)) { \
337 WARN_ONCE(!rcu_is_watching(), \
338 "RCU not watching for tracepoint"); \
339 } \
340 } \
341 static inline void trace_call__##name(proto) \
342 { \
343 might_fault(); \
344 __do_trace_##name(args); \
345 }
346
347 /*
348 * We have no guarantee that gcc and the linker won't up-align the tracepoint
349 * structures, so we create an array of pointers that will be used for iteration
350 * on the tracepoints.
351 *
352 * it_func[0] is never NULL because there is at least one element in the array
353 * when the array itself is non NULL.
354 */
355 #define __DEFINE_TRACE_EXT(_name, _ext, proto, args) \
356 static const char __tpstrtab_##_name[] \
357 __section("__tracepoints_strings") = #_name; \
358 extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \
359 int __traceiter_##_name(void *__data, proto); \
360 void __probestub_##_name(void *__data, proto); \
361 struct tracepoint __tracepoint_##_name __used \
362 __section("__tracepoints") = { \
363 .name = __tpstrtab_##_name, \
364 .key = STATIC_KEY_FALSE_INIT, \
365 .static_call_key = &STATIC_CALL_KEY(tp_func_##_name), \
366 .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
367 .iterator = &__traceiter_##_name, \
368 .probestub = &__probestub_##_name, \
369 .funcs = NULL, \
370 .ext = _ext, \
371 }; \
372 __TRACEPOINT_ENTRY(_name); \
373 int __traceiter_##_name(void *__data, proto) \
374 { \
375 struct tracepoint_func *it_func_ptr; \
376 void *it_func; \
377 \
378 it_func_ptr = \
379 rcu_dereference_raw((&__tracepoint_##_name)->funcs); \
380 if (it_func_ptr) { \
381 do { \
382 it_func = READ_ONCE((it_func_ptr)->func); \
383 __data = (it_func_ptr)->data; \
384 ((void(*)(void *, proto))(it_func))(__data, args); \
385 } while ((++it_func_ptr)->func); \
386 } \
387 return 0; \
388 } \
389 void __probestub_##_name(void *__data, proto) \
390 { \
391 } \
392 DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name); \
393 DEFINE_RUST_DO_TRACE(_name, TP_PROTO(proto), TP_ARGS(args))
394
395 #define DEFINE_TRACE_FN(_name, _reg, _unreg, _proto, _args) \
396 static struct tracepoint_ext __tracepoint_ext_##_name = { \
397 .regfunc = _reg, \
398 .unregfunc = _unreg, \
399 .faultable = false, \
400 }; \
401 __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
402
403 #define DEFINE_TRACE_SYSCALL(_name, _reg, _unreg, _proto, _args) \
404 static struct tracepoint_ext __tracepoint_ext_##_name = { \
405 .regfunc = _reg, \
406 .unregfunc = _unreg, \
407 .faultable = true, \
408 }; \
409 __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
410
411 #define DEFINE_TRACE(_name, _proto, _args) \
412 __DEFINE_TRACE_EXT(_name, NULL, PARAMS(_proto), PARAMS(_args));
413
414 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
415 TRACEPOINT_CHECK(name) \
416 EXPORT_SYMBOL_GPL(__tracepoint_##name); \
417 EXPORT_SYMBOL_GPL(__traceiter_##name); \
418 EXPORT_STATIC_CALL_GPL(tp_func_##name)
419 #define EXPORT_TRACEPOINT_SYMBOL(name) \
420 TRACEPOINT_CHECK(name) \
421 EXPORT_SYMBOL(__tracepoint_##name); \
422 EXPORT_SYMBOL(__traceiter_##name); \
423 EXPORT_STATIC_CALL(tp_func_##name)
424
425
426 #else /* !TRACEPOINTS_ENABLED */
427 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto) \
428 static inline void trace_##name(proto) \
429 { } \
430 static inline void trace_call__##name(proto) \
431 { } \
432 static inline int \
433 register_trace_##name(void (*probe)(data_proto), \
434 void *data) \
435 { \
436 return -ENOSYS; \
437 } \
438 static inline int \
439 unregister_trace_##name(void (*probe)(data_proto), \
440 void *data) \
441 { \
442 return -ENOSYS; \
443 } \
444 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
445 { \
446 } \
447 static inline bool \
448 trace_##name##_enabled(void) \
449 { \
450 return false; \
451 }
452
453 #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
454 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
455
456 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto) \
457 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
458
459 #define DEFINE_TRACE_FN(name, reg, unreg, proto, args)
460 #define DEFINE_TRACE_SYSCALL(name, reg, unreg, proto, args)
461 #define DEFINE_TRACE(name, proto, args)
462 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
463 #define EXPORT_TRACEPOINT_SYMBOL(name)
464
465 #endif /* TRACEPOINTS_ENABLED */
466
467 #ifdef CONFIG_TRACING
468 /**
469 * tracepoint_string - register constant persistent string to trace system
470 * @str - a constant persistent string that will be referenced in tracepoints
471 *
472 * If constant strings are being used in tracepoints, it is faster and
473 * more efficient to just save the pointer to the string and reference
474 * that with a printf "%s" instead of saving the string in the ring buffer
475 * and wasting space and time.
476 *
477 * The problem with the above approach is that userspace tools that read
478 * the binary output of the trace buffers do not have access to the string.
479 * Instead they just show the address of the string which is not very
480 * useful to users.
481 *
482 * With tracepoint_string(), the string will be registered to the tracing
483 * system and exported to userspace via the debugfs/tracing/printk_formats
484 * file that maps the string address to the string text. This way userspace
485 * tools that read the binary buffers have a way to map the pointers to
486 * the ASCII strings they represent.
487 *
488 * The @str used must be a constant string and persistent as it would not
489 * make sense to show a string that no longer exists. But it is still fine
490 * to be used with modules, because when modules are unloaded, if they
491 * had tracepoints, the ring buffers are cleared too. As long as the string
492 * does not change during the life of the module, it is fine to use
493 * tracepoint_string() within a module.
494 */
495 #define tracepoint_string(str) \
496 ({ \
497 static const char *___tp_str __tracepoint_string = str; \
498 ___tp_str; \
499 })
500 #define __tracepoint_string __used __section("__tracepoint_str")
501 #else
502 /*
503 * tracepoint_string() is used to save the string address for userspace
504 * tracing tools. When tracing isn't configured, there's no need to save
505 * anything.
506 */
507 # define tracepoint_string(str) str
508 # define __tracepoint_string
509 #endif
510
511 #define DECLARE_TRACE(name, proto, args) \
512 __DECLARE_TRACE(name##_tp, PARAMS(proto), PARAMS(args), \
513 cpu_online(raw_smp_processor_id()), \
514 PARAMS(void *__data, proto))
515
516 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
517 __DECLARE_TRACE(name##_tp, PARAMS(proto), PARAMS(args), \
518 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
519 PARAMS(void *__data, proto))
520
521 #define DECLARE_TRACE_SYSCALL(name, proto, args) \
522 __DECLARE_TRACE_SYSCALL(name##_tp, PARAMS(proto), PARAMS(args), \
523 PARAMS(void *__data, proto))
524
525 #define DECLARE_TRACE_EVENT(name, proto, args) \
526 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
527 cpu_online(raw_smp_processor_id()), \
528 PARAMS(void *__data, proto))
529
530 #define DECLARE_TRACE_EVENT_CONDITION(name, proto, args, cond) \
531 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
532 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
533 PARAMS(void *__data, proto))
534
535 #define DECLARE_TRACE_EVENT_SYSCALL(name, proto, args) \
536 __DECLARE_TRACE_SYSCALL(name, PARAMS(proto), PARAMS(args), \
537 PARAMS(void *__data, proto))
538
539 #define TRACE_EVENT_FLAGS(event, flag)
540
541 #define TRACE_EVENT_PERF_PERM(event, expr...)
542
543 #endif /* DECLARE_TRACE */
544
545 #ifndef TRACE_EVENT
546 /*
547 * For use with the TRACE_EVENT macro:
548 *
549 * We define a tracepoint, its arguments, its printk format
550 * and its 'fast binary record' layout.
551 *
552 * Firstly, name your tracepoint via TRACE_EVENT(name : the
553 * 'subsystem_event' notation is fine.
554 *
555 * Think about this whole construct as the
556 * 'trace_sched_switch() function' from now on.
557 *
558 *
559 * TRACE_EVENT(sched_switch,
560 *
561 * *
562 * * A function has a regular function arguments
563 * * prototype, declare it via TP_PROTO():
564 * *
565 *
566 * TP_PROTO(struct rq *rq, struct task_struct *prev,
567 * struct task_struct *next),
568 *
569 * *
570 * * Define the call signature of the 'function'.
571 * * (Design sidenote: we use this instead of a
572 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
573 * *
574 *
575 * TP_ARGS(rq, prev, next),
576 *
577 * *
578 * * Fast binary tracing: define the trace record via
579 * * TP_STRUCT__entry(). You can think about it like a
580 * * regular C structure local variable definition.
581 * *
582 * * This is how the trace record is structured and will
583 * * be saved into the ring buffer. These are the fields
584 * * that will be exposed to user-space in
585 * * /sys/kernel/tracing/events/<*>/format.
586 * *
587 * * The declared 'local variable' is called '__entry'
588 * *
589 * * __field(pid_t, prev_pid) is equivalent to a standard declaration:
590 * *
591 * * pid_t prev_pid;
592 * *
593 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
594 * *
595 * * char prev_comm[TASK_COMM_LEN];
596 * *
597 *
598 * TP_STRUCT__entry(
599 * __array( char, prev_comm, TASK_COMM_LEN )
600 * __field( pid_t, prev_pid )
601 * __field( int, prev_prio )
602 * __array( char, next_comm, TASK_COMM_LEN )
603 * __field( pid_t, next_pid )
604 * __field( int, next_prio )
605 * ),
606 *
607 * *
608 * * Assign the entry into the trace record, by embedding
609 * * a full C statement block into TP_fast_assign(). You
610 * * can refer to the trace record as '__entry' -
611 * * otherwise you can put arbitrary C code in here.
612 * *
613 * * Note: this C code will execute every time a trace event
614 * * happens, on an active tracepoint.
615 * *
616 *
617 * TP_fast_assign(
618 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
619 * __entry->prev_pid = prev->pid;
620 * __entry->prev_prio = prev->prio;
621 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
622 * __entry->next_pid = next->pid;
623 * __entry->next_prio = next->prio;
624 * ),
625 *
626 * *
627 * * Formatted output of a trace record via TP_printk().
628 * * This is how the tracepoint will appear under ftrace
629 * * plugins that make use of this tracepoint.
630 * *
631 * * (raw-binary tracing wont actually perform this step.)
632 * *
633 *
634 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
635 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
636 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
637 *
638 * );
639 *
640 * This macro construct is thus used for the regular printk format
641 * tracing setup, it is used to construct a function pointer based
642 * tracepoint callback (this is used by programmatic plugins and
643 * can also by used by generic instrumentation like SystemTap), and
644 * it is also used to expose a structured trace record in
645 * /sys/kernel/tracing/events/.
646 *
647 * A set of (un)registration functions can be passed to the variant
648 * TRACE_EVENT_FN to perform any (un)registration work.
649 */
650
651 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
652 #define DEFINE_EVENT(template, name, proto, args) \
653 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
654 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
655 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
656 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
657 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
658 #define DEFINE_EVENT_CONDITION(template, name, proto, \
659 args, cond) \
660 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
661 PARAMS(args), PARAMS(cond))
662
663 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
664 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
665 #define TRACE_EVENT_FN(name, proto, args, struct, \
666 assign, print, reg, unreg) \
667 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
668 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
669 assign, print, reg, unreg) \
670 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
671 PARAMS(args), PARAMS(cond))
672 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
673 struct, assign, print) \
674 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
675 PARAMS(args), PARAMS(cond))
676 #define TRACE_EVENT_SYSCALL(name, proto, args, struct, assign, \
677 print, reg, unreg) \
678 DECLARE_TRACE_EVENT_SYSCALL(name, PARAMS(proto), PARAMS(args))
679
680 #define TRACE_EVENT_FLAGS(event, flag)
681
682 #define TRACE_EVENT_PERF_PERM(event, expr...)
683
684 #define DECLARE_EVENT_NOP(name, proto, args) \
685 static inline void trace_##name(proto) \
686 { } \
687 static inline bool trace_##name##_enabled(void) \
688 { \
689 return false; \
690 }
691
692 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) \
693 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
694
695 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
696 #define DEFINE_EVENT_NOP(template, name, proto, args) \
697 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
698
699 #endif /* ifdef TRACE_EVENT (see note above) */
700