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 static inline bool \
300 trace_##name##_enabled(void) \
301 { \
302 if (IS_ENABLED(CONFIG_LOCKDEP)) { \
303 WARN_ONCE(!rcu_is_watching(), \
304 "RCU not watching for tracepoint"); \
305 } \
306 return __trace_##name##_enabled(); \
307 }
308
309 #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
310 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
311 static inline void __do_trace_##name(proto) \
312 { \
313 TRACEPOINT_CHECK(name) \
314 if (cond) { \
315 guard(srcu_fast_notrace)(&tracepoint_srcu); \
316 __DO_TRACE_CALL(name, TP_ARGS(args)); \
317 } \
318 } \
319 static inline void trace_##name(proto) \
320 { \
321 if (static_branch_unlikely(&__tracepoint_##name.key)) \
322 __do_trace_##name(args); \
323 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
324 WARN_ONCE(!rcu_is_watching(), \
325 "RCU not watching for tracepoint"); \
326 } \
327 } \
328 static inline void trace_call__##name(proto) \
329 { \
330 __do_trace_##name(args); \
331 }
332
333 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto) \
334 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
335 static inline void __do_trace_##name(proto) \
336 { \
337 TRACEPOINT_CHECK(name) \
338 guard(rcu_tasks_trace)(); \
339 __DO_TRACE_CALL(name, TP_ARGS(args)); \
340 } \
341 static inline void trace_##name(proto) \
342 { \
343 might_fault(); \
344 if (static_branch_unlikely(&__tracepoint_##name.key)) \
345 __do_trace_##name(args); \
346 if (IS_ENABLED(CONFIG_LOCKDEP)) { \
347 WARN_ONCE(!rcu_is_watching(), \
348 "RCU not watching for tracepoint"); \
349 } \
350 } \
351 static inline void trace_call__##name(proto) \
352 { \
353 might_fault(); \
354 __do_trace_##name(args); \
355 }
356
357 /*
358 * We have no guarantee that gcc and the linker won't up-align the tracepoint
359 * structures, so we create an array of pointers that will be used for iteration
360 * on the tracepoints.
361 *
362 * it_func[0] is never NULL because there is at least one element in the array
363 * when the array itself is non NULL.
364 */
365 #define __DEFINE_TRACE_EXT(_name, _ext, proto, args) \
366 static const char __tpstrtab_##_name[] \
367 __section("__tracepoints_strings") = #_name; \
368 extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \
369 int __traceiter_##_name(void *__data, proto); \
370 void __probestub_##_name(void *__data, proto); \
371 struct tracepoint __tracepoint_##_name __used \
372 __section("__tracepoints") = { \
373 .name = __tpstrtab_##_name, \
374 .key = STATIC_KEY_FALSE_INIT, \
375 .static_call_key = &STATIC_CALL_KEY(tp_func_##_name), \
376 .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
377 .iterator = &__traceiter_##_name, \
378 .probestub = &__probestub_##_name, \
379 .funcs = NULL, \
380 .ext = _ext, \
381 }; \
382 __TRACEPOINT_ENTRY(_name); \
383 int __traceiter_##_name(void *__data, proto) \
384 { \
385 struct tracepoint_func *it_func_ptr; \
386 void *it_func; \
387 \
388 it_func_ptr = \
389 rcu_dereference_raw((&__tracepoint_##_name)->funcs); \
390 if (it_func_ptr) { \
391 do { \
392 it_func = READ_ONCE((it_func_ptr)->func); \
393 __data = (it_func_ptr)->data; \
394 ((void(*)(void *, proto))(it_func))(__data, args); \
395 } while ((++it_func_ptr)->func); \
396 } \
397 return 0; \
398 } \
399 void __probestub_##_name(void *__data, proto) \
400 { \
401 } \
402 /* \
403 * Annotate the probestub 'CFI_NOSEAL' to stop objtool from \
404 * requesting the kernel remove the ENDBR, because the only \
405 * references to the function are in the __tracepoint section, \
406 * that objtool doesn't scan. \
407 */ \
408 CFI_NOSEAL(__probestub_##_name); \
409 DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name); \
410 DEFINE_RUST_DO_TRACE(_name, TP_PROTO(proto), TP_ARGS(args))
411
412 #define DEFINE_TRACE_FN(_name, _reg, _unreg, _proto, _args) \
413 static struct tracepoint_ext __tracepoint_ext_##_name = { \
414 .regfunc = _reg, \
415 .unregfunc = _unreg, \
416 .faultable = false, \
417 }; \
418 __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
419
420 #define DEFINE_TRACE_SYSCALL(_name, _reg, _unreg, _proto, _args) \
421 static struct tracepoint_ext __tracepoint_ext_##_name = { \
422 .regfunc = _reg, \
423 .unregfunc = _unreg, \
424 .faultable = true, \
425 }; \
426 __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
427
428 #define DEFINE_TRACE(_name, _proto, _args) \
429 __DEFINE_TRACE_EXT(_name, NULL, PARAMS(_proto), PARAMS(_args));
430
431 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
432 TRACEPOINT_CHECK(name) \
433 EXPORT_SYMBOL_GPL(__tracepoint_##name); \
434 EXPORT_SYMBOL_GPL(__traceiter_##name); \
435 EXPORT_STATIC_CALL_GPL(tp_func_##name)
436 #define EXPORT_TRACEPOINT_SYMBOL(name) \
437 TRACEPOINT_CHECK(name) \
438 EXPORT_SYMBOL(__tracepoint_##name); \
439 EXPORT_SYMBOL(__traceiter_##name); \
440 EXPORT_STATIC_CALL(tp_func_##name)
441
442
443 #else /* !TRACEPOINTS_ENABLED */
444 #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto) \
445 static inline void trace_##name(proto) \
446 { } \
447 static inline void trace_call__##name(proto) \
448 { } \
449 static inline int \
450 register_trace_##name(void (*probe)(data_proto), \
451 void *data) \
452 { \
453 return -ENOSYS; \
454 } \
455 static inline int \
456 unregister_trace_##name(void (*probe)(data_proto), \
457 void *data) \
458 { \
459 return -ENOSYS; \
460 } \
461 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
462 { \
463 } \
464 static inline bool \
465 __trace_##name##_enabled(void) \
466 { \
467 return false; \
468 } \
469 static inline bool \
470 trace_##name##_enabled(void) \
471 { \
472 return false; \
473 }
474
475 #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
476 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
477
478 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto) \
479 __DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto))
480
481 #define DEFINE_TRACE_FN(name, reg, unreg, proto, args)
482 #define DEFINE_TRACE_SYSCALL(name, reg, unreg, proto, args)
483 #define DEFINE_TRACE(name, proto, args)
484 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
485 #define EXPORT_TRACEPOINT_SYMBOL(name)
486
487 #endif /* TRACEPOINTS_ENABLED */
488
489 #ifdef CONFIG_TRACING
490 /**
491 * tracepoint_string - register constant persistent string to trace system
492 * @str - a constant persistent string that will be referenced in tracepoints
493 *
494 * If constant strings are being used in tracepoints, it is faster and
495 * more efficient to just save the pointer to the string and reference
496 * that with a printf "%s" instead of saving the string in the ring buffer
497 * and wasting space and time.
498 *
499 * The problem with the above approach is that userspace tools that read
500 * the binary output of the trace buffers do not have access to the string.
501 * Instead they just show the address of the string which is not very
502 * useful to users.
503 *
504 * With tracepoint_string(), the string will be registered to the tracing
505 * system and exported to userspace via the debugfs/tracing/printk_formats
506 * file that maps the string address to the string text. This way userspace
507 * tools that read the binary buffers have a way to map the pointers to
508 * the ASCII strings they represent.
509 *
510 * The @str used must be a constant string and persistent as it would not
511 * make sense to show a string that no longer exists. But it is still fine
512 * to be used with modules, because when modules are unloaded, if they
513 * had tracepoints, the ring buffers are cleared too. As long as the string
514 * does not change during the life of the module, it is fine to use
515 * tracepoint_string() within a module.
516 */
517 #define tracepoint_string(str) \
518 ({ \
519 static const char *___tp_str __tracepoint_string = str; \
520 ___tp_str; \
521 })
522 #define __tracepoint_string __used __section("__tracepoint_str")
523 #else
524 /*
525 * tracepoint_string() is used to save the string address for userspace
526 * tracing tools. When tracing isn't configured, there's no need to save
527 * anything.
528 */
529 # define tracepoint_string(str) str
530 # define __tracepoint_string
531 #endif
532
533 #define DECLARE_TRACE(name, proto, args) \
534 __DECLARE_TRACE(name##_tp, PARAMS(proto), PARAMS(args), \
535 cpu_online(raw_smp_processor_id()), \
536 PARAMS(void *__data, proto))
537
538 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
539 __DECLARE_TRACE(name##_tp, PARAMS(proto), PARAMS(args), \
540 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
541 PARAMS(void *__data, proto))
542
543 #define DECLARE_TRACE_SYSCALL(name, proto, args) \
544 __DECLARE_TRACE_SYSCALL(name##_tp, PARAMS(proto), PARAMS(args), \
545 PARAMS(void *__data, proto))
546
547 #define DECLARE_TRACE_EVENT(name, proto, args) \
548 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
549 cpu_online(raw_smp_processor_id()), \
550 PARAMS(void *__data, proto))
551
552 #define DECLARE_TRACE_EVENT_CONDITION(name, proto, args, cond) \
553 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
554 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
555 PARAMS(void *__data, proto))
556
557 #define DECLARE_TRACE_EVENT_SYSCALL(name, proto, args) \
558 __DECLARE_TRACE_SYSCALL(name, PARAMS(proto), PARAMS(args), \
559 PARAMS(void *__data, proto))
560
561 #define TRACE_EVENT_FLAGS(event, flag)
562
563 #define TRACE_EVENT_PERF_PERM(event, expr...)
564
565 #endif /* DECLARE_TRACE */
566
567 #ifndef TRACE_EVENT
568 /*
569 * For use with the TRACE_EVENT macro:
570 *
571 * We define a tracepoint, its arguments, its printk format
572 * and its 'fast binary record' layout.
573 *
574 * Firstly, name your tracepoint via TRACE_EVENT(name : the
575 * 'subsystem_event' notation is fine.
576 *
577 * Think about this whole construct as the
578 * 'trace_sched_switch() function' from now on.
579 *
580 *
581 * TRACE_EVENT(sched_switch,
582 *
583 * *
584 * * A function has a regular function arguments
585 * * prototype, declare it via TP_PROTO():
586 * *
587 *
588 * TP_PROTO(struct rq *rq, struct task_struct *prev,
589 * struct task_struct *next),
590 *
591 * *
592 * * Define the call signature of the 'function'.
593 * * (Design sidenote: we use this instead of a
594 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
595 * *
596 *
597 * TP_ARGS(rq, prev, next),
598 *
599 * *
600 * * Fast binary tracing: define the trace record via
601 * * TP_STRUCT__entry(). You can think about it like a
602 * * regular C structure local variable definition.
603 * *
604 * * This is how the trace record is structured and will
605 * * be saved into the ring buffer. These are the fields
606 * * that will be exposed to user-space in
607 * * /sys/kernel/tracing/events/<*>/format.
608 * *
609 * * The declared 'local variable' is called '__entry'
610 * *
611 * * __field(pid_t, prev_pid) is equivalent to a standard declaration:
612 * *
613 * * pid_t prev_pid;
614 * *
615 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
616 * *
617 * * char prev_comm[TASK_COMM_LEN];
618 * *
619 *
620 * TP_STRUCT__entry(
621 * __array( char, prev_comm, TASK_COMM_LEN )
622 * __field( pid_t, prev_pid )
623 * __field( int, prev_prio )
624 * __array( char, next_comm, TASK_COMM_LEN )
625 * __field( pid_t, next_pid )
626 * __field( int, next_prio )
627 * ),
628 *
629 * *
630 * * Assign the entry into the trace record, by embedding
631 * * a full C statement block into TP_fast_assign(). You
632 * * can refer to the trace record as '__entry' -
633 * * otherwise you can put arbitrary C code in here.
634 * *
635 * * Note: this C code will execute every time a trace event
636 * * happens, on an active tracepoint.
637 * *
638 *
639 * TP_fast_assign(
640 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
641 * __entry->prev_pid = prev->pid;
642 * __entry->prev_prio = prev->prio;
643 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
644 * __entry->next_pid = next->pid;
645 * __entry->next_prio = next->prio;
646 * ),
647 *
648 * *
649 * * Formatted output of a trace record via TP_printk().
650 * * This is how the tracepoint will appear under ftrace
651 * * plugins that make use of this tracepoint.
652 * *
653 * * (raw-binary tracing wont actually perform this step.)
654 * *
655 *
656 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
657 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
658 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
659 *
660 * );
661 *
662 * This macro construct is thus used for the regular printk format
663 * tracing setup, it is used to construct a function pointer based
664 * tracepoint callback (this is used by programmatic plugins and
665 * can also by used by generic instrumentation like SystemTap), and
666 * it is also used to expose a structured trace record in
667 * /sys/kernel/tracing/events/.
668 *
669 * A set of (un)registration functions can be passed to the variant
670 * TRACE_EVENT_FN to perform any (un)registration work.
671 */
672
673 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
674 #define DEFINE_EVENT(template, name, proto, args) \
675 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
676 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
677 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
678 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
679 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
680 #define DEFINE_EVENT_CONDITION(template, name, proto, \
681 args, cond) \
682 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
683 PARAMS(args), PARAMS(cond))
684
685 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
686 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
687 #define TRACE_EVENT_FN(name, proto, args, struct, \
688 assign, print, reg, unreg) \
689 DECLARE_TRACE_EVENT(name, PARAMS(proto), PARAMS(args))
690 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
691 assign, print, reg, unreg) \
692 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
693 PARAMS(args), PARAMS(cond))
694 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
695 struct, assign, print) \
696 DECLARE_TRACE_EVENT_CONDITION(name, PARAMS(proto), \
697 PARAMS(args), PARAMS(cond))
698 #define TRACE_EVENT_SYSCALL(name, proto, args, struct, assign, \
699 print, reg, unreg) \
700 DECLARE_TRACE_EVENT_SYSCALL(name, PARAMS(proto), PARAMS(args))
701
702 #define TRACE_EVENT_FLAGS(event, flag)
703
704 #define TRACE_EVENT_PERF_PERM(event, expr...)
705
706 #define DECLARE_EVENT_NOP(name, proto, args) \
707 static inline void trace_##name(proto) \
708 { } \
709 static inline bool trace_##name##_enabled(void) \
710 { \
711 return false; \
712 }
713
714 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) \
715 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
716
717 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
718 #define DEFINE_EVENT_NOP(template, name, proto, args) \
719 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
720
721 #endif /* ifdef TRACE_EVENT (see note above) */
722