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