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