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