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 #include <linux/cfi.h>
24
25 struct module;
26 struct tracepoint;
27 struct notifier_block;
28
29 struct trace_eval_map {
30 const char *system;
31 const char *eval_string;
32 unsigned long eval_value;
33 };
34
35 #define TRACEPOINT_DEFAULT_PRIO 10
36
37 extern int
38 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
39 extern int
40 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
41 int prio);
42 extern int
43 tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe, void *data,
44 int prio);
45 extern int
46 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
47 static inline int
tracepoint_probe_register_may_exist(struct tracepoint * tp,void * probe,void * data)48 tracepoint_probe_register_may_exist(struct tracepoint *tp, void *probe,
49 void *data)
50 {
51 return tracepoint_probe_register_prio_may_exist(tp, probe, data,
52 TRACEPOINT_DEFAULT_PRIO);
53 }
54 extern void
55 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
56 void *priv);
57
58 #ifdef CONFIG_MODULES
59 struct tp_module {
60 struct list_head list;
61 struct module *mod;
62 };
63
64 bool trace_module_has_bad_taint(struct module *mod);
65 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
66 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
67 void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
68 struct module *, void *),
69 void *priv);
70 void for_each_tracepoint_in_module(struct module *,
71 void (*fct)(struct tracepoint *,
72 struct module *, void *),
73 void *priv);
74 #else
trace_module_has_bad_taint(struct module * mod)75 static inline bool trace_module_has_bad_taint(struct module *mod)
76 {
77 return false;
78 }
79 static inline
register_tracepoint_module_notifier(struct notifier_block * nb)80 int register_tracepoint_module_notifier(struct notifier_block *nb)
81 {
82 return 0;
83 }
84 static inline
unregister_tracepoint_module_notifier(struct notifier_block * nb)85 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
86 {
87 return 0;
88 }
89 static inline
for_each_module_tracepoint(void (* fct)(struct tracepoint *,struct module *,void *),void * priv)90 void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
91 struct module *, void *),
92 void *priv)
93 {
94 }
95 static inline
for_each_tracepoint_in_module(struct module * mod,void (* fct)(struct tracepoint *,struct module *,void *),void * priv)96 void for_each_tracepoint_in_module(struct module *mod,
97 void (*fct)(struct tracepoint *,
98 struct module *, void *),
99 void *priv)
100 {
101 }
102 #endif /* CONFIG_MODULES */
103
104 /*
105 * tracepoint_synchronize_unregister must be called between the last tracepoint
106 * probe unregistration and the end of module exit to make sure there is no
107 * caller executing a probe when it is freed.
108 *
109 * An alternative is to use the following for batch reclaim associated
110 * with a given tracepoint:
111 *
112 * - tracepoint_is_faultable() == false: call_srcu()
113 * - tracepoint_is_faultable() == true: call_rcu_tasks_trace()
114 */
115 #ifdef CONFIG_TRACEPOINTS
116 extern struct srcu_struct tracepoint_srcu;
tracepoint_synchronize_unregister(void)117 static inline void tracepoint_synchronize_unregister(void)
118 {
119 synchronize_rcu_tasks_trace();
120 synchronize_srcu(&tracepoint_srcu);
121 }
tracepoint_is_faultable(struct tracepoint * tp)122 static inline bool tracepoint_is_faultable(struct tracepoint *tp)
123 {
124 return tp->ext && tp->ext->faultable;
125 }
126 /*
127 * Run RCU callback with the appropriate grace period wait for non-faultable
128 * tracepoints, e.g., those used in atomic context.
129 */
call_tracepoint_unregister_atomic(struct rcu_head * rcu,rcu_callback_t func)130 static inline void call_tracepoint_unregister_atomic(struct rcu_head *rcu, rcu_callback_t func)
131 {
132 call_srcu(&tracepoint_srcu, rcu, func);
133 }
134 /*
135 * Run RCU callback with the appropriate grace period wait for faultable
136 * tracepoints, e.g., those used in syscall context.
137 */
call_tracepoint_unregister_syscall(struct rcu_head * rcu,rcu_callback_t func)138 static inline void call_tracepoint_unregister_syscall(struct rcu_head *rcu, rcu_callback_t func)
139 {
140 call_rcu_tasks_trace(rcu, func);
141 }
142 #else
tracepoint_synchronize_unregister(void)143 static inline void tracepoint_synchronize_unregister(void)
144 { }
tracepoint_is_faultable(struct tracepoint * tp)145 static inline bool tracepoint_is_faultable(struct tracepoint *tp)
146 {
147 return false;
148 }
call_tracepoint_unregister_atomic(struct rcu_head * rcu,rcu_callback_t func)149 static inline void call_tracepoint_unregister_atomic(struct rcu_head *rcu, rcu_callback_t func)
150 { }
call_tracepoint_unregister_syscall(struct rcu_head * rcu,rcu_callback_t func)151 static inline void call_tracepoint_unregister_syscall(struct rcu_head *rcu, rcu_callback_t func)
152 { }
153 #endif
154
155 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
156 extern int syscall_regfunc(void);
157 extern void syscall_unregfunc(void);
158 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
159
160 #ifndef PARAMS
161 #define PARAMS(args...) args
162 #endif
163
164 #define TRACE_DEFINE_ENUM(x)
165 #define TRACE_DEFINE_SIZEOF(x)
166
167 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
tracepoint_ptr_deref(tracepoint_ptr_t * p)168 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
169 {
170 return offset_to_ptr(p);
171 }
172
173 #define __TRACEPOINT_ENTRY(name) \
174 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \
175 " .balign 4 \n" \
176 " .long __tracepoint_" #name " - . \n" \
177 " .previous \n")
178 #else
tracepoint_ptr_deref(tracepoint_ptr_t * p)179 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
180 {
181 return *p;
182 }
183
184 #define __TRACEPOINT_ENTRY(name) \
185 static tracepoint_ptr_t __tracepoint_ptr_##name __used \
186 __section("__tracepoints_ptrs") = &__tracepoint_##name
187 #endif
188
189 #endif /* _LINUX_TRACEPOINT_H */
190
191 /*
192 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
193 * file ifdef protection.
194 * This is due to the way trace events work. If a file includes two
195 * trace event headers under one "CREATE_TRACE_POINTS" the first include
196 * will override the TRACE_EVENT and break the second include.
197 */
198
199 #ifndef DECLARE_TRACE
200
201 #define TP_PROTO(args...) args
202 #define TP_ARGS(args...) args
203 #define TP_CONDITION(args...) args
204
205 /*
206 * Individual subsystem may have a separate configuration to
207 * enable their tracepoints. By default, this file will create
208 * the tracepoints if CONFIG_TRACEPOINTS is defined. If a subsystem
209 * wants to be able to disable its tracepoints from being created
210 * it can define NOTRACE before including the tracepoint headers.
211 */
212 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
213 #define TRACEPOINTS_ENABLED
214 #endif
215
216 #ifdef TRACEPOINTS_ENABLED
217
218 #ifdef CONFIG_HAVE_STATIC_CALL
219 #define __DO_TRACE_CALL(name, args) \
220 do { \
221 struct tracepoint_func *it_func_ptr; \
222 void *__data; \
223 it_func_ptr = \
224 rcu_dereference_raw((&__tracepoint_##name)->funcs); \
225 if (it_func_ptr) { \
226 __data = (it_func_ptr)->data; \
227 static_call(tp_func_##name)(__data, args); \
228 } \
229 } while (0)
230 #else
231 #define __DO_TRACE_CALL(name, args) __traceiter_##name(NULL, args)
232 #endif /* CONFIG_HAVE_STATIC_CALL */
233
234 /*
235 * Declare an exported function that Rust code can call to trigger this
236 * tracepoint. This function does not include the static branch; that is done
237 * in Rust to avoid a function call when the tracepoint is disabled.
238 */
239 #define DEFINE_RUST_DO_TRACE(name, proto, args)
240 #define __DEFINE_RUST_DO_TRACE(name, proto, args) \
241 notrace void rust_do_trace_##name(proto) \
242 { \
243 __do_trace_##name(args); \
244 }
245
246 /*
247 * When a tracepoint is used, it's name is added to the __tracepoint_check
248 * section. This section is only used at build time to make sure all
249 * defined tracepoints are used. It is discarded after the build.
250 */
251 # define TRACEPOINT_CHECK(name) \
252 static const char __used __section("__tracepoint_check") \
253 __trace_check_##name[] = #name;
254
255 /*
256 * Make sure the alignment of the structure in the __tracepoints section will
257 * not add unwanted padding between the beginning of the section and the
258 * structure. Force alignment to the same alignment as the section start.
259 *
260 * When lockdep is enabled, we make sure to always test if RCU is
261 * "watching" regardless if the tracepoint is enabled or not. Tracepoints
262 * require RCU to be active, and it should always warn at the tracepoint
263 * site if it is not watching, as it will need to be active when the
264 * tracepoint is enabled.
265 */
266 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto) \
267 extern int __traceiter_##name(data_proto); \
268 DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name); \
269 extern struct tracepoint __tracepoint_##name; \
270 extern void rust_do_trace_##name(proto); \
271 static inline int \
272 register_trace_##name(void (*probe)(data_proto), void *data) \
273 { \
274 return tracepoint_probe_register(&__tracepoint_##name, \
275 (void *)probe, data); \
276 } \
277 static inline int \
278 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
279 int prio) \
280 { \
281 return tracepoint_probe_register_prio(&__tracepoint_##name, \
282 (void *)probe, data, prio); \
283 } \
284 static inline int \
285 unregister_trace_##name(void (*probe)(data_proto), void *data) \
286 { \
287 return tracepoint_probe_unregister(&__tracepoint_##name,\
288 (void *)probe, data); \
289 } \
290 static inline void \
291 check_trace_callback_type_##name(void (*cb)(data_proto)) \
292 { \
293 } \
294 static inline bool \
295 trace_##name##_enabled(void) \
296 { \
297 return static_branch_unlikely(&__tracepoint_##name.key);\
298 }
299
300 #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
301 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
302 static inline void __do_trace_##name(proto) \
303 { \
304 TRACEPOINT_CHECK(name) \
305 if (cond) { \
306 guard(srcu_fast_notrace)(&tracepoint_srcu); \
307 __DO_TRACE_CALL(name, TP_ARGS(args)); \
308 } \
309 } \
310 static inline void trace_##name(proto) \
311 { \
312 if (static_branch_unlikely(&__tracepoint_##name.key)) \
313 __do_trace_##name(args); \
314 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
315 WARN_ONCE(!rcu_is_watching(), \
316 "RCU not watching for tracepoint"); \
317 } \
318 } \
319 static inline void trace_call__##name(proto) \
320 { \
321 __do_trace_##name(args); \
322 }
323
324 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto) \
325 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
326 static inline void __do_trace_##name(proto) \
327 { \
328 TRACEPOINT_CHECK(name) \
329 guard(rcu_tasks_trace)(); \
330 __DO_TRACE_CALL(name, TP_ARGS(args)); \
331 } \
332 static inline void trace_##name(proto) \
333 { \
334 might_fault(); \
335 if (static_branch_unlikely(&__tracepoint_##name.key)) \
336 __do_trace_##name(args); \
337 if (IS_ENABLED(CONFIG_LOCKDEP)) { \
338 WARN_ONCE(!rcu_is_watching(), \
339 "RCU not watching for tracepoint"); \
340 } \
341 } \
342 static inline void trace_call__##name(proto) \
343 { \
344 might_fault(); \
345 __do_trace_##name(args); \
346 }
347
348 /*
349 * We have no guarantee that gcc and the linker won't up-align the tracepoint
350 * structures, so we create an array of pointers that will be used for iteration
351 * on the tracepoints.
352 *
353 * it_func[0] is never NULL because there is at least one element in the array
354 * when the array itself is non NULL.
355 */
356 #define __DEFINE_TRACE_EXT(_name, _ext, proto, args) \
357 static const char __tpstrtab_##_name[] \
358 __section("__tracepoints_strings") = #_name; \
359 extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \
360 int __traceiter_##_name(void *__data, proto); \
361 void __probestub_##_name(void *__data, proto); \
362 struct tracepoint __tracepoint_##_name __used \
363 __section("__tracepoints") = { \
364 .name = __tpstrtab_##_name, \
365 .key = STATIC_KEY_FALSE_INIT, \
366 .static_call_key = &STATIC_CALL_KEY(tp_func_##_name), \
367 .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
368 .iterator = &__traceiter_##_name, \
369 .probestub = &__probestub_##_name, \
370 .funcs = NULL, \
371 .ext = _ext, \
372 }; \
373 __TRACEPOINT_ENTRY(_name); \
374 int __traceiter_##_name(void *__data, proto) \
375 { \
376 struct tracepoint_func *it_func_ptr; \
377 void *it_func; \
378 \
379 it_func_ptr = \
380 rcu_dereference_raw((&__tracepoint_##_name)->funcs); \
381 if (it_func_ptr) { \
382 do { \
383 it_func = READ_ONCE((it_func_ptr)->func); \
384 __data = (it_func_ptr)->data; \
385 ((void(*)(void *, proto))(it_func))(__data, args); \
386 } while ((++it_func_ptr)->func); \
387 } \
388 return 0; \
389 } \
390 void __probestub_##_name(void *__data, proto) \
391 { \
392 } \
393 /* \
394 * Annotate the probestub 'CFI_NOSEAL' to stop objtool from \
395 * requesting the kernel remove the ENDBR, because the only \
396 * references to the function are in the __tracepoint section, \
397 * that objtool doesn't scan. \
398 */ \
399 CFI_NOSEAL(__probestub_##_name); \
400 DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name); \
401 DEFINE_RUST_DO_TRACE(_name, TP_PROTO(proto), TP_ARGS(args))
402
403 #define DEFINE_TRACE_FN(_name, _reg, _unreg, _proto, _args) \
404 static struct tracepoint_ext __tracepoint_ext_##_name = { \
405 .regfunc = _reg, \
406 .unregfunc = _unreg, \
407 .faultable = false, \
408 }; \
409 __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
410
411 #define DEFINE_TRACE_SYSCALL(_name, _reg, _unreg, _proto, _args) \
412 static struct tracepoint_ext __tracepoint_ext_##_name = { \
413 .regfunc = _reg, \
414 .unregfunc = _unreg, \
415 .faultable = true, \
416 }; \
417 __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
418
419 #define DEFINE_TRACE(_name, _proto, _args) \
420 __DEFINE_TRACE_EXT(_name, NULL, PARAMS(_proto), PARAMS(_args));
421
422 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
423 TRACEPOINT_CHECK(name) \
424 EXPORT_SYMBOL_GPL(__tracepoint_##name); \
425 EXPORT_SYMBOL_GPL(__traceiter_##name); \
426 EXPORT_STATIC_CALL_GPL(tp_func_##name)
427 #define EXPORT_TRACEPOINT_SYMBOL(name) \
428 TRACEPOINT_CHECK(name) \
429 EXPORT_SYMBOL(__tracepoint_##name); \
430 EXPORT_SYMBOL(__traceiter_##name); \
431 EXPORT_STATIC_CALL(tp_func_##name)
432
433
434 #else /* !TRACEPOINTS_ENABLED */
435 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto) \
436 static inline void trace_##name(proto) \
437 { } \
438 static inline void trace_call__##name(proto) \
439 { } \
440 static inline int \
441 register_trace_##name(void (*probe)(data_proto), \
442 void *data) \
443 { \
444 return -ENOSYS; \
445 } \
446 static inline int \
447 unregister_trace_##name(void (*probe)(data_proto), \
448 void *data) \
449 { \
450 return -ENOSYS; \
451 } \
452 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
453 { \
454 } \
455 static inline bool \
456 trace_##name##_enabled(void) \
457 { \
458 return false; \
459 }
460
461 #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
462 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
463
464 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto) \
465 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
466
467 #define DEFINE_TRACE_FN(name, reg, unreg, proto, args)
468 #define DEFINE_TRACE_SYSCALL(name, reg, unreg, proto, args)
469 #define DEFINE_TRACE(name, proto, args)
470 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
471 #define EXPORT_TRACEPOINT_SYMBOL(name)
472
473 #endif /* TRACEPOINTS_ENABLED */
474
475 #ifdef CONFIG_TRACING
476 /**
477 * tracepoint_string - register constant persistent string to trace system
478 * @str - a constant persistent string that will be referenced in tracepoints
479 *
480 * If constant strings are being used in tracepoints, it is faster and
481 * more efficient to just save the pointer to the string and reference
482 * that with a printf "%s" instead of saving the string in the ring buffer
483 * and wasting space and time.
484 *
485 * The problem with the above approach is that userspace tools that read
486 * the binary output of the trace buffers do not have access to the string.
487 * Instead they just show the address of the string which is not very
488 * useful to users.
489 *
490 * With tracepoint_string(), the string will be registered to the tracing
491 * system and exported to userspace via the debugfs/tracing/printk_formats
492 * file that maps the string address to the string text. This way userspace
493 * tools that read the binary buffers have a way to map the pointers to
494 * the ASCII strings they represent.
495 *
496 * The @str used must be a constant string and persistent as it would not
497 * make sense to show a string that no longer exists. But it is still fine
498 * to be used with modules, because when modules are unloaded, if they
499 * had tracepoints, the ring buffers are cleared too. As long as the string
500 * does not change during the life of the module, it is fine to use
501 * tracepoint_string() within a module.
502 */
503 #define tracepoint_string(str) \
504 ({ \
505 static const char *___tp_str __tracepoint_string = str; \
506 ___tp_str; \
507 })
508 #define __tracepoint_string __used __section("__tracepoint_str")
509 #else
510 /*
511 * tracepoint_string() is used to save the string address for userspace
512 * tracing tools. When tracing isn't configured, there's no need to save
513 * anything.
514 */
515 # define tracepoint_string(str) str
516 # define __tracepoint_string
517 #endif
518
519 #define DECLARE_TRACE(name, proto, args) \
520 __DECLARE_TRACE(name##_tp, PARAMS(proto), PARAMS(args), \
521 cpu_online(raw_smp_processor_id()), \
522 PARAMS(void *__data, proto))
523
524 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
525 __DECLARE_TRACE(name##_tp, PARAMS(proto), PARAMS(args), \
526 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
527 PARAMS(void *__data, proto))
528
529 #define DECLARE_TRACE_SYSCALL(name, proto, args) \
530 __DECLARE_TRACE_SYSCALL(name##_tp, PARAMS(proto), PARAMS(args), \
531 PARAMS(void *__data, proto))
532
533 #define DECLARE_TRACE_EVENT(name, proto, args) \
534 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
535 cpu_online(raw_smp_processor_id()), \
536 PARAMS(void *__data, proto))
537
538 #define DECLARE_TRACE_EVENT_CONDITION(name, proto, args, cond) \
539 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
540 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
541 PARAMS(void *__data, proto))
542
543 #define DECLARE_TRACE_EVENT_SYSCALL(name, proto, args) \
544 __DECLARE_TRACE_SYSCALL(name, PARAMS(proto), PARAMS(args), \
545 PARAMS(void *__data, proto))
546
547 #define TRACE_EVENT_FLAGS(event, flag)
548
549 #define TRACE_EVENT_PERF_PERM(event, expr...)
550
551 #endif /* DECLARE_TRACE */
552
553 #ifndef TRACE_EVENT
554 /*
555 * For use with the TRACE_EVENT macro:
556 *
557 * We define a tracepoint, its arguments, its printk format
558 * and its 'fast binary record' layout.
559 *
560 * Firstly, name your tracepoint via TRACE_EVENT(name : the
561 * 'subsystem_event' notation is fine.
562 *
563 * Think about this whole construct as the
564 * 'trace_sched_switch() function' from now on.
565 *
566 *
567 * TRACE_EVENT(sched_switch,
568 *
569 * *
570 * * A function has a regular function arguments
571 * * prototype, declare it via TP_PROTO():
572 * *
573 *
574 * TP_PROTO(struct rq *rq, struct task_struct *prev,
575 * struct task_struct *next),
576 *
577 * *
578 * * Define the call signature of the 'function'.
579 * * (Design sidenote: we use this instead of a
580 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
581 * *
582 *
583 * TP_ARGS(rq, prev, next),
584 *
585 * *
586 * * Fast binary tracing: define the trace record via
587 * * TP_STRUCT__entry(). You can think about it like a
588 * * regular C structure local variable definition.
589 * *
590 * * This is how the trace record is structured and will
591 * * be saved into the ring buffer. These are the fields
592 * * that will be exposed to user-space in
593 * * /sys/kernel/tracing/events/<*>/format.
594 * *
595 * * The declared 'local variable' is called '__entry'
596 * *
597 * * __field(pid_t, prev_pid) is equivalent to a standard declaration:
598 * *
599 * * pid_t prev_pid;
600 * *
601 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
602 * *
603 * * char prev_comm[TASK_COMM_LEN];
604 * *
605 *
606 * TP_STRUCT__entry(
607 * __array( char, prev_comm, TASK_COMM_LEN )
608 * __field( pid_t, prev_pid )
609 * __field( int, prev_prio )
610 * __array( char, next_comm, TASK_COMM_LEN )
611 * __field( pid_t, next_pid )
612 * __field( int, next_prio )
613 * ),
614 *
615 * *
616 * * Assign the entry into the trace record, by embedding
617 * * a full C statement block into TP_fast_assign(). You
618 * * can refer to the trace record as '__entry' -
619 * * otherwise you can put arbitrary C code in here.
620 * *
621 * * Note: this C code will execute every time a trace event
622 * * happens, on an active tracepoint.
623 * *
624 *
625 * TP_fast_assign(
626 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
627 * __entry->prev_pid = prev->pid;
628 * __entry->prev_prio = prev->prio;
629 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
630 * __entry->next_pid = next->pid;
631 * __entry->next_prio = next->prio;
632 * ),
633 *
634 * *
635 * * Formatted output of a trace record via TP_printk().
636 * * This is how the tracepoint will appear under ftrace
637 * * plugins that make use of this tracepoint.
638 * *
639 * * (raw-binary tracing wont actually perform this step.)
640 * *
641 *
642 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
643 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
644 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
645 *
646 * );
647 *
648 * This macro construct is thus used for the regular printk format
649 * tracing setup, it is used to construct a function pointer based
650 * tracepoint callback (this is used by programmatic plugins and
651 * can also by used by generic instrumentation like SystemTap), and
652 * it is also used to expose a structured trace record in
653 * /sys/kernel/tracing/events/.
654 *
655 * A set of (un)registration functions can be passed to the variant
656 * TRACE_EVENT_FN to perform any (un)registration work.
657 */
658
659 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
660 #define DEFINE_EVENT(template, name, proto, args) \
661 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
662 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
663 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
664 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
665 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
666 #define DEFINE_EVENT_CONDITION(template, name, proto, \
667 args, cond) \
668 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
669 PARAMS(args), PARAMS(cond))
670
671 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
672 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
673 #define TRACE_EVENT_FN(name, proto, args, struct, \
674 assign, print, reg, unreg) \
675 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
676 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
677 assign, print, reg, unreg) \
678 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
679 PARAMS(args), PARAMS(cond))
680 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
681 struct, assign, print) \
682 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
683 PARAMS(args), PARAMS(cond))
684 #define TRACE_EVENT_SYSCALL(name, proto, args, struct, assign, \
685 print, reg, unreg) \
686 DECLARE_TRACE_EVENT_SYSCALL(name, PARAMS(proto), PARAMS(args))
687
688 #define TRACE_EVENT_FLAGS(event, flag)
689
690 #define TRACE_EVENT_PERF_PERM(event, expr...)
691
692 #define DECLARE_EVENT_NOP(name, proto, args) \
693 static inline void trace_##name(proto) \
694 { } \
695 static inline bool trace_##name##_enabled(void) \
696 { \
697 return false; \
698 }
699
700 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) \
701 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
702
703 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
704 #define DEFINE_EVENT_NOP(template, name, proto, args) \
705 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
706
707 #endif /* ifdef TRACE_EVENT (see note above) */
708