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/cpumask.h>
20 #include <linux/rcupdate.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 struct srcu_struct tracepoint_srcu;
37
38 extern int
39 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
40 extern int
41 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
42 int prio);
43 extern int
44 tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe, void *data,
45 int prio);
46 extern int
47 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
48 static inline int
tracepoint_probe_register_may_exist(struct tracepoint * tp,void * probe,void * data)49 tracepoint_probe_register_may_exist(struct tracepoint *tp, void *probe,
50 void *data)
51 {
52 return tracepoint_probe_register_prio_may_exist(tp, probe, data,
53 TRACEPOINT_DEFAULT_PRIO);
54 }
55 extern void
56 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
57 void *priv);
58
59 #ifdef CONFIG_MODULES
60 struct tp_module {
61 struct list_head list;
62 struct module *mod;
63 };
64
65 bool trace_module_has_bad_taint(struct module *mod);
66 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
67 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
68 #else
trace_module_has_bad_taint(struct module * mod)69 static inline bool trace_module_has_bad_taint(struct module *mod)
70 {
71 return false;
72 }
73 static inline
register_tracepoint_module_notifier(struct notifier_block * nb)74 int register_tracepoint_module_notifier(struct notifier_block *nb)
75 {
76 return 0;
77 }
78 static inline
unregister_tracepoint_module_notifier(struct notifier_block * nb)79 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
80 {
81 return 0;
82 }
83 #endif /* CONFIG_MODULES */
84
85 /*
86 * tracepoint_synchronize_unregister must be called between the last tracepoint
87 * probe unregistration and the end of module exit to make sure there is no
88 * caller executing a probe when it is freed.
89 */
90 #ifdef CONFIG_TRACEPOINTS
tracepoint_synchronize_unregister(void)91 static inline void tracepoint_synchronize_unregister(void)
92 {
93 synchronize_srcu(&tracepoint_srcu);
94 synchronize_rcu();
95 }
96 #else
tracepoint_synchronize_unregister(void)97 static inline void tracepoint_synchronize_unregister(void)
98 { }
99 #endif
100
101 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
102 extern int syscall_regfunc(void);
103 extern void syscall_unregfunc(void);
104 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
105
106 #ifndef PARAMS
107 #define PARAMS(args...) args
108 #endif
109
110 #define TRACE_DEFINE_ENUM(x)
111 #define TRACE_DEFINE_SIZEOF(x)
112
113 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
tracepoint_ptr_deref(tracepoint_ptr_t * p)114 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
115 {
116 return offset_to_ptr(p);
117 }
118
119 #define __TRACEPOINT_ENTRY(name) \
120 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \
121 " .balign 4 \n" \
122 " .long __tracepoint_" #name " - . \n" \
123 " .previous \n")
124 #else
tracepoint_ptr_deref(tracepoint_ptr_t * p)125 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
126 {
127 return *p;
128 }
129
130 #define __TRACEPOINT_ENTRY(name) \
131 static tracepoint_ptr_t __tracepoint_ptr_##name __used \
132 __section("__tracepoints_ptrs") = &__tracepoint_##name
133 #endif
134
135 #endif /* _LINUX_TRACEPOINT_H */
136
137 /*
138 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
139 * file ifdef protection.
140 * This is due to the way trace events work. If a file includes two
141 * trace event headers under one "CREATE_TRACE_POINTS" the first include
142 * will override the TRACE_EVENT and break the second include.
143 */
144
145 #ifndef DECLARE_TRACE
146
147 #define TP_PROTO(args...) args
148 #define TP_ARGS(args...) args
149 #define TP_CONDITION(args...) args
150
151 /*
152 * Individual subsystem my have a separate configuration to
153 * enable their tracepoints. By default, this file will create
154 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
155 * wants to be able to disable its tracepoints from being created
156 * it can define NOTRACE before including the tracepoint headers.
157 */
158 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
159 #define TRACEPOINTS_ENABLED
160 #endif
161
162 #ifdef TRACEPOINTS_ENABLED
163
164 #ifdef CONFIG_HAVE_STATIC_CALL
165 #define __DO_TRACE_CALL(name) static_call(tp_func_##name)
166 #else
167 #define __DO_TRACE_CALL(name) __traceiter_##name
168 #endif /* CONFIG_HAVE_STATIC_CALL */
169
170 /*
171 * it_func[0] is never NULL because there is at least one element in the array
172 * when the array itself is non NULL.
173 *
174 * Note, the proto and args passed in includes "__data" as the first parameter.
175 * The reason for this is to handle the "void" prototype. If a tracepoint
176 * has a "void" prototype, then it is invalid to declare a function
177 * as "(void *, void)".
178 */
179 #define __DO_TRACE(name, proto, args, cond, rcuidle) \
180 do { \
181 struct tracepoint_func *it_func_ptr; \
182 int __maybe_unused __idx = 0; \
183 void *__data; \
184 \
185 if (!(cond)) \
186 return; \
187 \
188 /* srcu can't be used from NMI */ \
189 WARN_ON_ONCE(rcuidle && in_nmi()); \
190 \
191 /* keep srcu and sched-rcu usage consistent */ \
192 preempt_disable_notrace(); \
193 \
194 /* \
195 * For rcuidle callers, use srcu since sched-rcu \
196 * doesn't work from the idle path. \
197 */ \
198 if (rcuidle) { \
199 __idx = srcu_read_lock_notrace(&tracepoint_srcu);\
200 rcu_irq_enter_irqson(); \
201 } \
202 \
203 it_func_ptr = \
204 rcu_dereference_raw((&__tracepoint_##name)->funcs); \
205 if (it_func_ptr) { \
206 __data = (it_func_ptr)->data; \
207 __DO_TRACE_CALL(name)(args); \
208 } \
209 \
210 if (rcuidle) { \
211 rcu_irq_exit_irqson(); \
212 srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
213 } \
214 \
215 preempt_enable_notrace(); \
216 } while (0)
217
218 #ifndef MODULE
219 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
220 static inline void trace_##name##_rcuidle(proto) \
221 { \
222 if (static_key_false(&__tracepoint_##name.key)) \
223 __DO_TRACE(name, \
224 TP_PROTO(data_proto), \
225 TP_ARGS(data_args), \
226 TP_CONDITION(cond), 1); \
227 }
228 #else
229 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
230 #endif
231
232 /*
233 * Make sure the alignment of the structure in the __tracepoints section will
234 * not add unwanted padding between the beginning of the section and the
235 * structure. Force alignment to the same alignment as the section start.
236 *
237 * When lockdep is enabled, we make sure to always test if RCU is
238 * "watching" regardless if the tracepoint is enabled or not. Tracepoints
239 * require RCU to be active, and it should always warn at the tracepoint
240 * site if it is not watching, as it will need to be active when the
241 * tracepoint is enabled.
242 */
243 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
244 extern int __traceiter_##name(data_proto); \
245 DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name); \
246 extern struct tracepoint __tracepoint_##name; \
247 static inline void __nocfi trace_##name(proto) \
248 { \
249 if (static_key_false(&__tracepoint_##name.key)) \
250 __DO_TRACE(name, \
251 TP_PROTO(data_proto), \
252 TP_ARGS(data_args), \
253 TP_CONDITION(cond), 0); \
254 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
255 WARN_ON_ONCE(!rcu_is_watching()); \
256 } \
257 } \
258 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
259 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
260 static inline int \
261 register_trace_##name(void (*probe)(data_proto), void *data) \
262 { \
263 return tracepoint_probe_register(&__tracepoint_##name, \
264 (void *)probe, data); \
265 } \
266 static inline int \
267 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
268 int prio) \
269 { \
270 return tracepoint_probe_register_prio(&__tracepoint_##name, \
271 (void *)probe, data, prio); \
272 } \
273 static inline int \
274 unregister_trace_##name(void (*probe)(data_proto), void *data) \
275 { \
276 return tracepoint_probe_unregister(&__tracepoint_##name,\
277 (void *)probe, data); \
278 } \
279 static inline void \
280 check_trace_callback_type_##name(void (*cb)(data_proto)) \
281 { \
282 } \
283 static inline bool \
284 trace_##name##_enabled(void) \
285 { \
286 return static_key_false(&__tracepoint_##name.key); \
287 }
288
289 /*
290 * We have no guarantee that gcc and the linker won't up-align the tracepoint
291 * structures, so we create an array of pointers that will be used for iteration
292 * on the tracepoints.
293 */
294 #define DEFINE_TRACE_FN(_name, _reg, _unreg, proto, args) \
295 static const char __tpstrtab_##_name[] \
296 __section("__tracepoints_strings") = #_name; \
297 extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \
298 int __traceiter_##_name(void *__data, proto); \
299 struct tracepoint __tracepoint_##_name __used \
300 __section("__tracepoints") = { \
301 .name = __tpstrtab_##_name, \
302 .key = STATIC_KEY_INIT_FALSE, \
303 .static_call_key = &STATIC_CALL_KEY(tp_func_##_name), \
304 .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
305 .iterator = &__traceiter_##_name, \
306 .regfunc = _reg, \
307 .unregfunc = _unreg, \
308 .funcs = NULL }; \
309 __TRACEPOINT_ENTRY(_name); \
310 int __nocfi __traceiter_##_name(void *__data, proto) \
311 { \
312 struct tracepoint_func *it_func_ptr; \
313 void *it_func; \
314 \
315 it_func_ptr = \
316 rcu_dereference_raw((&__tracepoint_##_name)->funcs); \
317 if (it_func_ptr) { \
318 do { \
319 it_func = (it_func_ptr)->func; \
320 __data = (it_func_ptr)->data; \
321 ((void(*)(void *, proto))(it_func))(__data, args); \
322 } while ((++it_func_ptr)->func); \
323 } \
324 return 0; \
325 } \
326 DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name);
327
328 #define DEFINE_TRACE(name, proto, args) \
329 DEFINE_TRACE_FN(name, NULL, NULL, PARAMS(proto), PARAMS(args));
330
331 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
332 EXPORT_SYMBOL_GPL(__tracepoint_##name); \
333 EXPORT_SYMBOL_GPL(__traceiter_##name); \
334 EXPORT_STATIC_CALL_GPL(tp_func_##name)
335 #define EXPORT_TRACEPOINT_SYMBOL(name) \
336 EXPORT_SYMBOL(__tracepoint_##name); \
337 EXPORT_SYMBOL(__traceiter_##name); \
338 EXPORT_STATIC_CALL(tp_func_##name)
339
340
341 #else /* !TRACEPOINTS_ENABLED */
342 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
343 static inline void trace_##name(proto) \
344 { } \
345 static inline void trace_##name##_rcuidle(proto) \
346 { } \
347 static inline int \
348 register_trace_##name(void (*probe)(data_proto), \
349 void *data) \
350 { \
351 return -ENOSYS; \
352 } \
353 static inline int \
354 unregister_trace_##name(void (*probe)(data_proto), \
355 void *data) \
356 { \
357 return -ENOSYS; \
358 } \
359 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
360 { \
361 } \
362 static inline bool \
363 trace_##name##_enabled(void) \
364 { \
365 return false; \
366 }
367
368 #define DEFINE_TRACE_FN(name, reg, unreg, proto, args)
369 #define DEFINE_TRACE(name, proto, args)
370 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
371 #define EXPORT_TRACEPOINT_SYMBOL(name)
372
373 #endif /* TRACEPOINTS_ENABLED */
374
375 #ifdef CONFIG_TRACING
376 /**
377 * tracepoint_string - register constant persistent string to trace system
378 * @str - a constant persistent string that will be referenced in tracepoints
379 *
380 * If constant strings are being used in tracepoints, it is faster and
381 * more efficient to just save the pointer to the string and reference
382 * that with a printf "%s" instead of saving the string in the ring buffer
383 * and wasting space and time.
384 *
385 * The problem with the above approach is that userspace tools that read
386 * the binary output of the trace buffers do not have access to the string.
387 * Instead they just show the address of the string which is not very
388 * useful to users.
389 *
390 * With tracepoint_string(), the string will be registered to the tracing
391 * system and exported to userspace via the debugfs/tracing/printk_formats
392 * file that maps the string address to the string text. This way userspace
393 * tools that read the binary buffers have a way to map the pointers to
394 * the ASCII strings they represent.
395 *
396 * The @str used must be a constant string and persistent as it would not
397 * make sense to show a string that no longer exists. But it is still fine
398 * to be used with modules, because when modules are unloaded, if they
399 * had tracepoints, the ring buffers are cleared too. As long as the string
400 * does not change during the life of the module, it is fine to use
401 * tracepoint_string() within a module.
402 */
403 #define tracepoint_string(str) \
404 ({ \
405 static const char *___tp_str __tracepoint_string = str; \
406 ___tp_str; \
407 })
408 #define __tracepoint_string __used __section("__tracepoint_str")
409 #else
410 /*
411 * tracepoint_string() is used to save the string address for userspace
412 * tracing tools. When tracing isn't configured, there's no need to save
413 * anything.
414 */
415 # define tracepoint_string(str) str
416 # define __tracepoint_string
417 #endif
418
419 #define DECLARE_TRACE(name, proto, args) \
420 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
421 cpu_online(raw_smp_processor_id()), \
422 PARAMS(void *__data, proto), \
423 PARAMS(__data, args))
424
425 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
426 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
427 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
428 PARAMS(void *__data, proto), \
429 PARAMS(__data, args))
430
431 #define TRACE_EVENT_FLAGS(event, flag)
432
433 #define TRACE_EVENT_PERF_PERM(event, expr...)
434
435 #endif /* DECLARE_TRACE */
436
437 #ifndef TRACE_EVENT
438 /*
439 * For use with the TRACE_EVENT macro:
440 *
441 * We define a tracepoint, its arguments, its printk format
442 * and its 'fast binary record' layout.
443 *
444 * Firstly, name your tracepoint via TRACE_EVENT(name : the
445 * 'subsystem_event' notation is fine.
446 *
447 * Think about this whole construct as the
448 * 'trace_sched_switch() function' from now on.
449 *
450 *
451 * TRACE_EVENT(sched_switch,
452 *
453 * *
454 * * A function has a regular function arguments
455 * * prototype, declare it via TP_PROTO():
456 * *
457 *
458 * TP_PROTO(struct rq *rq, struct task_struct *prev,
459 * struct task_struct *next),
460 *
461 * *
462 * * Define the call signature of the 'function'.
463 * * (Design sidenote: we use this instead of a
464 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
465 * *
466 *
467 * TP_ARGS(rq, prev, next),
468 *
469 * *
470 * * Fast binary tracing: define the trace record via
471 * * TP_STRUCT__entry(). You can think about it like a
472 * * regular C structure local variable definition.
473 * *
474 * * This is how the trace record is structured and will
475 * * be saved into the ring buffer. These are the fields
476 * * that will be exposed to user-space in
477 * * /sys/kernel/debug/tracing/events/<*>/format.
478 * *
479 * * The declared 'local variable' is called '__entry'
480 * *
481 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
482 * *
483 * * pid_t prev_pid;
484 * *
485 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
486 * *
487 * * char prev_comm[TASK_COMM_LEN];
488 * *
489 *
490 * TP_STRUCT__entry(
491 * __array( char, prev_comm, TASK_COMM_LEN )
492 * __field( pid_t, prev_pid )
493 * __field( int, prev_prio )
494 * __array( char, next_comm, TASK_COMM_LEN )
495 * __field( pid_t, next_pid )
496 * __field( int, next_prio )
497 * ),
498 *
499 * *
500 * * Assign the entry into the trace record, by embedding
501 * * a full C statement block into TP_fast_assign(). You
502 * * can refer to the trace record as '__entry' -
503 * * otherwise you can put arbitrary C code in here.
504 * *
505 * * Note: this C code will execute every time a trace event
506 * * happens, on an active tracepoint.
507 * *
508 *
509 * TP_fast_assign(
510 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
511 * __entry->prev_pid = prev->pid;
512 * __entry->prev_prio = prev->prio;
513 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
514 * __entry->next_pid = next->pid;
515 * __entry->next_prio = next->prio;
516 * ),
517 *
518 * *
519 * * Formatted output of a trace record via TP_printk().
520 * * This is how the tracepoint will appear under ftrace
521 * * plugins that make use of this tracepoint.
522 * *
523 * * (raw-binary tracing wont actually perform this step.)
524 * *
525 *
526 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
527 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
528 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
529 *
530 * );
531 *
532 * This macro construct is thus used for the regular printk format
533 * tracing setup, it is used to construct a function pointer based
534 * tracepoint callback (this is used by programmatic plugins and
535 * can also by used by generic instrumentation like SystemTap), and
536 * it is also used to expose a structured trace record in
537 * /sys/kernel/debug/tracing/events/.
538 *
539 * A set of (un)registration functions can be passed to the variant
540 * TRACE_EVENT_FN to perform any (un)registration work.
541 */
542
543 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
544 #define DEFINE_EVENT(template, name, proto, args) \
545 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
546 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
547 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
548 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
549 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
550 #define DEFINE_EVENT_CONDITION(template, name, proto, \
551 args, cond) \
552 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
553 PARAMS(args), PARAMS(cond))
554
555 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
556 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
557 #define TRACE_EVENT_FN(name, proto, args, struct, \
558 assign, print, reg, unreg) \
559 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
560 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
561 assign, print, reg, unreg) \
562 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
563 PARAMS(args), PARAMS(cond))
564 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
565 struct, assign, print) \
566 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
567 PARAMS(args), PARAMS(cond))
568
569 #define TRACE_EVENT_FLAGS(event, flag)
570
571 #define TRACE_EVENT_PERF_PERM(event, expr...)
572
573 #define DECLARE_EVENT_NOP(name, proto, args) \
574 static inline void trace_##name(proto) \
575 { } \
576 static inline bool trace_##name##_enabled(void) \
577 { \
578 return false; \
579 }
580
581 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) \
582 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
583
584 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
585 #define DEFINE_EVENT_NOP(template, name, proto, args) \
586 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
587
588 #endif /* ifdef TRACE_EVENT (see note above) */
589