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_TRACEPOINTS 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, args) \
166 do { \
167 struct tracepoint_func *it_func_ptr; \
168 void *__data; \
169 it_func_ptr = \
170 rcu_dereference_raw((&__tracepoint_##name)->funcs); \
171 if (it_func_ptr) { \
172 __data = (it_func_ptr)->data; \
173 static_call(tp_func_##name)(__data, args); \
174 } \
175 } while (0)
176 #else
177 #define __DO_TRACE_CALL(name, args) __traceiter_##name(NULL, args)
178 #endif /* CONFIG_HAVE_STATIC_CALL */
179
180 /*
181 * ARCH_WANTS_NO_INSTR archs are expected to have sanitized entry and idle
182 * code that disallow any/all tracing/instrumentation when RCU isn't watching.
183 */
184 #ifdef CONFIG_ARCH_WANTS_NO_INSTR
185 #define RCUIDLE_COND(rcuidle) (rcuidle)
186 #else
187 /* srcu can't be used from NMI */
188 #define RCUIDLE_COND(rcuidle) (rcuidle && in_nmi())
189 #endif
190
191 /*
192 * it_func[0] is never NULL because there is at least one element in the array
193 * when the array itself is non NULL.
194 */
195 #define __DO_TRACE(name, args, cond, rcuidle) \
196 do { \
197 int __maybe_unused __idx = 0; \
198 \
199 if (!(cond)) \
200 return; \
201 \
202 if (WARN_ONCE(RCUIDLE_COND(rcuidle), \
203 "Bad RCU usage for tracepoint")) \
204 return; \
205 \
206 /* keep srcu and sched-rcu usage consistent */ \
207 preempt_disable_notrace(); \
208 \
209 /* \
210 * For rcuidle callers, use srcu since sched-rcu \
211 * doesn't work from the idle path. \
212 */ \
213 if (rcuidle) { \
214 __idx = srcu_read_lock_notrace(&tracepoint_srcu);\
215 ct_irq_enter_irqson(); \
216 } \
217 \
218 __DO_TRACE_CALL(name, TP_ARGS(args)); \
219 \
220 if (rcuidle) { \
221 ct_irq_exit_irqson(); \
222 srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
223 } \
224 \
225 preempt_enable_notrace(); \
226 } while (0)
227
228 #ifndef MODULE
229 #define __DECLARE_TRACE_RCU(name, proto, args, cond) \
230 static inline void trace_##name##_rcuidle(proto) \
231 { \
232 if (static_key_false(&__tracepoint_##name.key)) \
233 __DO_TRACE(name, \
234 TP_ARGS(args), \
235 TP_CONDITION(cond), 1); \
236 }
237 #else
238 #define __DECLARE_TRACE_RCU(name, proto, args, cond)
239 #endif
240
241 /*
242 * Make sure the alignment of the structure in the __tracepoints section will
243 * not add unwanted padding between the beginning of the section and the
244 * structure. Force alignment to the same alignment as the section start.
245 *
246 * When lockdep is enabled, we make sure to always test if RCU is
247 * "watching" regardless if the tracepoint is enabled or not. Tracepoints
248 * require RCU to be active, and it should always warn at the tracepoint
249 * site if it is not watching, as it will need to be active when the
250 * tracepoint is enabled.
251 */
252 #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
253 extern int __traceiter_##name(data_proto); \
254 DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name); \
255 extern struct tracepoint __tracepoint_##name; \
256 static inline void trace_##name(proto) \
257 { \
258 if (static_key_false(&__tracepoint_##name.key)) \
259 __DO_TRACE(name, \
260 TP_ARGS(args), \
261 TP_CONDITION(cond), 0); \
262 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
263 WARN_ONCE(!rcu_is_watching(), \
264 "RCU not watching for tracepoint"); \
265 } \
266 } \
267 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
268 PARAMS(cond)) \
269 static inline int \
270 register_trace_##name(void (*probe)(data_proto), void *data) \
271 { \
272 return tracepoint_probe_register(&__tracepoint_##name, \
273 (void *)probe, data); \
274 } \
275 static inline int \
276 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
277 int prio) \
278 { \
279 return tracepoint_probe_register_prio(&__tracepoint_##name, \
280 (void *)probe, data, prio); \
281 } \
282 static inline int \
283 unregister_trace_##name(void (*probe)(data_proto), void *data) \
284 { \
285 return tracepoint_probe_unregister(&__tracepoint_##name,\
286 (void *)probe, data); \
287 } \
288 static inline void \
289 check_trace_callback_type_##name(void (*cb)(data_proto)) \
290 { \
291 } \
292 static inline bool \
293 trace_##name##_enabled(void) \
294 { \
295 return static_key_false(&__tracepoint_##name.key); \
296 }
297
298 /*
299 * We have no guarantee that gcc and the linker won't up-align the tracepoint
300 * structures, so we create an array of pointers that will be used for iteration
301 * on the tracepoints.
302 */
303 #define DEFINE_TRACE_FN(_name, _reg, _unreg, proto, args) \
304 static const char __tpstrtab_##_name[] \
305 __section("__tracepoints_strings") = #_name; \
306 extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \
307 int __traceiter_##_name(void *__data, proto); \
308 void __probestub_##_name(void *__data, proto); \
309 struct tracepoint __tracepoint_##_name __used \
310 __section("__tracepoints") = { \
311 .name = __tpstrtab_##_name, \
312 .key = STATIC_KEY_INIT_FALSE, \
313 .static_call_key = &STATIC_CALL_KEY(tp_func_##_name), \
314 .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
315 .iterator = &__traceiter_##_name, \
316 .probestub = &__probestub_##_name, \
317 .regfunc = _reg, \
318 .unregfunc = _unreg, \
319 .funcs = NULL }; \
320 __TRACEPOINT_ENTRY(_name); \
321 int __traceiter_##_name(void *__data, proto) \
322 { \
323 struct tracepoint_func *it_func_ptr; \
324 void *it_func; \
325 \
326 it_func_ptr = \
327 rcu_dereference_raw((&__tracepoint_##_name)->funcs); \
328 if (it_func_ptr) { \
329 do { \
330 it_func = READ_ONCE((it_func_ptr)->func); \
331 __data = (it_func_ptr)->data; \
332 ((void(*)(void *, proto))(it_func))(__data, args); \
333 } while ((++it_func_ptr)->func); \
334 } \
335 return 0; \
336 } \
337 void __probestub_##_name(void *__data, proto) \
338 { \
339 } \
340 DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name);
341
342 #define DEFINE_TRACE(name, proto, args) \
343 DEFINE_TRACE_FN(name, NULL, NULL, PARAMS(proto), PARAMS(args));
344
345 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
346 EXPORT_SYMBOL_GPL(__tracepoint_##name); \
347 EXPORT_SYMBOL_GPL(__traceiter_##name); \
348 EXPORT_STATIC_CALL_GPL(tp_func_##name)
349 #define EXPORT_TRACEPOINT_SYMBOL(name) \
350 EXPORT_SYMBOL(__tracepoint_##name); \
351 EXPORT_SYMBOL(__traceiter_##name); \
352 EXPORT_STATIC_CALL(tp_func_##name)
353
354
355 #else /* !TRACEPOINTS_ENABLED */
356 #define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
357 static inline void trace_##name(proto) \
358 { } \
359 static inline void trace_##name##_rcuidle(proto) \
360 { } \
361 static inline int \
362 register_trace_##name(void (*probe)(data_proto), \
363 void *data) \
364 { \
365 return -ENOSYS; \
366 } \
367 static inline int \
368 unregister_trace_##name(void (*probe)(data_proto), \
369 void *data) \
370 { \
371 return -ENOSYS; \
372 } \
373 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
374 { \
375 } \
376 static inline bool \
377 trace_##name##_enabled(void) \
378 { \
379 return false; \
380 }
381
382 #define DEFINE_TRACE_FN(name, reg, unreg, proto, args)
383 #define DEFINE_TRACE(name, proto, args)
384 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
385 #define EXPORT_TRACEPOINT_SYMBOL(name)
386
387 #endif /* TRACEPOINTS_ENABLED */
388
389 #ifdef CONFIG_TRACING
390 /**
391 * tracepoint_string - register constant persistent string to trace system
392 * @str - a constant persistent string that will be referenced in tracepoints
393 *
394 * If constant strings are being used in tracepoints, it is faster and
395 * more efficient to just save the pointer to the string and reference
396 * that with a printf "%s" instead of saving the string in the ring buffer
397 * and wasting space and time.
398 *
399 * The problem with the above approach is that userspace tools that read
400 * the binary output of the trace buffers do not have access to the string.
401 * Instead they just show the address of the string which is not very
402 * useful to users.
403 *
404 * With tracepoint_string(), the string will be registered to the tracing
405 * system and exported to userspace via the debugfs/tracing/printk_formats
406 * file that maps the string address to the string text. This way userspace
407 * tools that read the binary buffers have a way to map the pointers to
408 * the ASCII strings they represent.
409 *
410 * The @str used must be a constant string and persistent as it would not
411 * make sense to show a string that no longer exists. But it is still fine
412 * to be used with modules, because when modules are unloaded, if they
413 * had tracepoints, the ring buffers are cleared too. As long as the string
414 * does not change during the life of the module, it is fine to use
415 * tracepoint_string() within a module.
416 */
417 #define tracepoint_string(str) \
418 ({ \
419 static const char *___tp_str __tracepoint_string = str; \
420 ___tp_str; \
421 })
422 #define __tracepoint_string __used __section("__tracepoint_str")
423 #else
424 /*
425 * tracepoint_string() is used to save the string address for userspace
426 * tracing tools. When tracing isn't configured, there's no need to save
427 * anything.
428 */
429 # define tracepoint_string(str) str
430 # define __tracepoint_string
431 #endif
432
433 #define DECLARE_TRACE(name, proto, args) \
434 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
435 cpu_online(raw_smp_processor_id()), \
436 PARAMS(void *__data, proto))
437
438 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
439 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
440 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
441 PARAMS(void *__data, proto))
442
443 #define TRACE_EVENT_FLAGS(event, flag)
444
445 #define TRACE_EVENT_PERF_PERM(event, expr...)
446
447 #endif /* DECLARE_TRACE */
448
449 #ifndef TRACE_EVENT
450 /*
451 * For use with the TRACE_EVENT macro:
452 *
453 * We define a tracepoint, its arguments, its printk format
454 * and its 'fast binary record' layout.
455 *
456 * Firstly, name your tracepoint via TRACE_EVENT(name : the
457 * 'subsystem_event' notation is fine.
458 *
459 * Think about this whole construct as the
460 * 'trace_sched_switch() function' from now on.
461 *
462 *
463 * TRACE_EVENT(sched_switch,
464 *
465 * *
466 * * A function has a regular function arguments
467 * * prototype, declare it via TP_PROTO():
468 * *
469 *
470 * TP_PROTO(struct rq *rq, struct task_struct *prev,
471 * struct task_struct *next),
472 *
473 * *
474 * * Define the call signature of the 'function'.
475 * * (Design sidenote: we use this instead of a
476 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
477 * *
478 *
479 * TP_ARGS(rq, prev, next),
480 *
481 * *
482 * * Fast binary tracing: define the trace record via
483 * * TP_STRUCT__entry(). You can think about it like a
484 * * regular C structure local variable definition.
485 * *
486 * * This is how the trace record is structured and will
487 * * be saved into the ring buffer. These are the fields
488 * * that will be exposed to user-space in
489 * * /sys/kernel/tracing/events/<*>/format.
490 * *
491 * * The declared 'local variable' is called '__entry'
492 * *
493 * * __field(pid_t, prev_pid) is equivalent to a standard declaration:
494 * *
495 * * pid_t prev_pid;
496 * *
497 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
498 * *
499 * * char prev_comm[TASK_COMM_LEN];
500 * *
501 *
502 * TP_STRUCT__entry(
503 * __array( char, prev_comm, TASK_COMM_LEN )
504 * __field( pid_t, prev_pid )
505 * __field( int, prev_prio )
506 * __array( char, next_comm, TASK_COMM_LEN )
507 * __field( pid_t, next_pid )
508 * __field( int, next_prio )
509 * ),
510 *
511 * *
512 * * Assign the entry into the trace record, by embedding
513 * * a full C statement block into TP_fast_assign(). You
514 * * can refer to the trace record as '__entry' -
515 * * otherwise you can put arbitrary C code in here.
516 * *
517 * * Note: this C code will execute every time a trace event
518 * * happens, on an active tracepoint.
519 * *
520 *
521 * TP_fast_assign(
522 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
523 * __entry->prev_pid = prev->pid;
524 * __entry->prev_prio = prev->prio;
525 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
526 * __entry->next_pid = next->pid;
527 * __entry->next_prio = next->prio;
528 * ),
529 *
530 * *
531 * * Formatted output of a trace record via TP_printk().
532 * * This is how the tracepoint will appear under ftrace
533 * * plugins that make use of this tracepoint.
534 * *
535 * * (raw-binary tracing wont actually perform this step.)
536 * *
537 *
538 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
539 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
540 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
541 *
542 * );
543 *
544 * This macro construct is thus used for the regular printk format
545 * tracing setup, it is used to construct a function pointer based
546 * tracepoint callback (this is used by programmatic plugins and
547 * can also by used by generic instrumentation like SystemTap), and
548 * it is also used to expose a structured trace record in
549 * /sys/kernel/tracing/events/.
550 *
551 * A set of (un)registration functions can be passed to the variant
552 * TRACE_EVENT_FN to perform any (un)registration work.
553 */
554
555 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
556 #define DEFINE_EVENT(template, name, proto, args) \
557 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
558 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
559 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
560 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
561 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
562 #define DEFINE_EVENT_CONDITION(template, name, proto, \
563 args, cond) \
564 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
565 PARAMS(args), PARAMS(cond))
566
567 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
568 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
569 #define TRACE_EVENT_FN(name, proto, args, struct, \
570 assign, print, reg, unreg) \
571 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
572 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
573 assign, print, reg, unreg) \
574 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
575 PARAMS(args), PARAMS(cond))
576 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
577 struct, assign, print) \
578 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
579 PARAMS(args), PARAMS(cond))
580
581 #define TRACE_EVENT_FLAGS(event, flag)
582
583 #define TRACE_EVENT_PERF_PERM(event, expr...)
584
585 #define DECLARE_EVENT_NOP(name, proto, args) \
586 static inline void trace_##name(proto) \
587 { } \
588 static inline bool trace_##name##_enabled(void) \
589 { \
590 return false; \
591 }
592
593 #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) \
594 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
595
596 #define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
597 #define DEFINE_EVENT_NOP(template, name, proto, args) \
598 DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
599
600 #endif /* ifdef TRACE_EVENT (see note above) */
601