1 #ifndef _LINUX_TRACEPOINT_H
2 #define _LINUX_TRACEPOINT_H
4 /*
5 * Kernel Tracepoint API.
6 *
7 * See Documentation/trace/tracepoints.rst.
8 *
9 * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 *
11 * Heavily inspired from the Linux Kernel Markers.
12 *
13 * This file is released under the GPLv2.
14 * See the file COPYING for more details.
15 */
17 #include <linux/smp.h>
18 #include <linux/srcu.h>
19 #include <linux/errno.h>
20 #include <linux/types.h>
21 #include <linux/cpumask.h>
22 #include <linux/rcupdate.h>
23 #include <linux/tracepoint-defs.h>
25 struct module;
26 struct tracepoint;
27 struct notifier_block;
29 struct trace_eval_map {
30 const char *system;
31 const char *eval_string;
32 unsigned long eval_value;
33 };
35 #define TRACEPOINT_DEFAULT_PRIO 10
37 extern struct srcu_struct tracepoint_srcu;
39 extern int
40 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
41 extern int
42 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
43 int prio);
44 extern int
45 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
46 extern void
47 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
48 void *priv);
50 #ifdef CONFIG_MODULES
51 struct tp_module {
52 struct list_head list;
53 struct module *mod;
54 };
56 bool trace_module_has_bad_taint(struct module *mod);
57 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
58 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
59 #else
60 static inline bool trace_module_has_bad_taint(struct module *mod)
61 {
62 return false;
63 }
64 static inline
65 int register_tracepoint_module_notifier(struct notifier_block *nb)
66 {
67 return 0;
68 }
69 static inline
70 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
71 {
72 return 0;
73 }
74 #endif /* CONFIG_MODULES */
76 /*
77 * tracepoint_synchronize_unregister must be called between the last tracepoint
78 * probe unregistration and the end of module exit to make sure there is no
79 * caller executing a probe when it is freed.
80 */
81 #ifdef CONFIG_TRACEPOINTS
82 static inline void tracepoint_synchronize_unregister(void)
83 {
84 synchronize_srcu(&tracepoint_srcu);
85 synchronize_sched();
86 }
87 #else
88 static inline void tracepoint_synchronize_unregister(void)
89 { }
90 #endif
92 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
93 extern int syscall_regfunc(void);
94 extern void syscall_unregfunc(void);
95 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
97 #define PARAMS(args...) args
99 #define TRACE_DEFINE_ENUM(x)
100 #define TRACE_DEFINE_SIZEOF(x)
102 #endif /* _LINUX_TRACEPOINT_H */
104 /*
105 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
106 * file ifdef protection.
107 * This is due to the way trace events work. If a file includes two
108 * trace event headers under one "CREATE_TRACE_POINTS" the first include
109 * will override the TRACE_EVENT and break the second include.
110 */
112 #ifndef DECLARE_TRACE
114 #define TP_PROTO(args...) args
115 #define TP_ARGS(args...) args
116 #define TP_CONDITION(args...) args
118 /*
119 * Individual subsystem my have a separate configuration to
120 * enable their tracepoints. By default, this file will create
121 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
122 * wants to be able to disable its tracepoints from being created
123 * it can define NOTRACE before including the tracepoint headers.
124 */
125 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
126 #define TRACEPOINTS_ENABLED
127 #endif
129 #ifdef TRACEPOINTS_ENABLED
131 /*
132 * it_func[0] is never NULL because there is at least one element in the array
133 * when the array itself is non NULL.
134 *
135 * Note, the proto and args passed in includes "__data" as the first parameter.
136 * The reason for this is to handle the "void" prototype. If a tracepoint
137 * has a "void" prototype, then it is invalid to declare a function
138 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
139 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
140 */
141 #define __DO_TRACE(tp, proto, args, cond, rcuidle) \
142 do { \
143 struct tracepoint_func *it_func_ptr; \
144 void *it_func; \
145 void *__data; \
146 int __maybe_unused idx = 0; \
147 \
148 if (!(cond)) \
149 return; \
150 \
151 /* srcu can't be used from NMI */ \
152 WARN_ON_ONCE(rcuidle && in_nmi()); \
153 \
154 /* keep srcu and sched-rcu usage consistent */ \
155 preempt_disable_notrace(); \
156 \
157 /* \
158 * For rcuidle callers, use srcu since sched-rcu \
159 * doesn't work from the idle path. \
160 */ \
161 if (rcuidle) { \
162 idx = srcu_read_lock_notrace(&tracepoint_srcu); \
163 rcu_irq_enter_irqson(); \
164 } \
165 \
166 it_func_ptr = rcu_dereference_raw((tp)->funcs); \
167 \
168 if (it_func_ptr) { \
169 do { \
170 it_func = (it_func_ptr)->func; \
171 __data = (it_func_ptr)->data; \
172 ((void(*)(proto))(it_func))(args); \
173 } while ((++it_func_ptr)->func); \
174 } \
175 \
176 if (rcuidle) { \
177 rcu_irq_exit_irqson(); \
178 srcu_read_unlock_notrace(&tracepoint_srcu, idx);\
179 } \
180 \
181 preempt_enable_notrace(); \
182 } while (0)
184 #ifndef MODULE
185 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
186 static inline void trace_##name##_rcuidle(proto) \
187 { \
188 if (static_key_false(&__tracepoint_##name.key)) \
189 __DO_TRACE(&__tracepoint_##name, \
190 TP_PROTO(data_proto), \
191 TP_ARGS(data_args), \
192 TP_CONDITION(cond), 1); \
193 }
194 #else
195 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
196 #endif
198 /*
199 * Make sure the alignment of the structure in the __tracepoints section will
200 * not add unwanted padding between the beginning of the section and the
201 * structure. Force alignment to the same alignment as the section start.
202 *
203 * When lockdep is enabled, we make sure to always do the RCU portions of
204 * the tracepoint code, regardless of whether tracing is on. However,
205 * don't check if the condition is false, due to interaction with idle
206 * instrumentation. This lets us find RCU issues triggered with tracepoints
207 * even when this tracepoint is off. This code has no purpose other than
208 * poking RCU a bit.
209 */
210 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
211 extern struct tracepoint __tracepoint_##name; \
212 static inline void trace_##name(proto) \
213 { \
214 if (static_key_false(&__tracepoint_##name.key)) \
215 __DO_TRACE(&__tracepoint_##name, \
216 TP_PROTO(data_proto), \
217 TP_ARGS(data_args), \
218 TP_CONDITION(cond), 0); \
219 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
220 rcu_read_lock_sched_notrace(); \
221 rcu_dereference_sched(__tracepoint_##name.funcs);\
222 rcu_read_unlock_sched_notrace(); \
223 } \
224 } \
225 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
226 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
227 static inline int \
228 register_trace_##name(void (*probe)(data_proto), void *data) \
229 { \
230 return tracepoint_probe_register(&__tracepoint_##name, \
231 (void *)probe, data); \
232 } \
233 static inline int \
234 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
235 int prio) \
236 { \
237 return tracepoint_probe_register_prio(&__tracepoint_##name, \
238 (void *)probe, data, prio); \
239 } \
240 static inline int \
241 unregister_trace_##name(void (*probe)(data_proto), void *data) \
242 { \
243 return tracepoint_probe_unregister(&__tracepoint_##name,\
244 (void *)probe, data); \
245 } \
246 static inline void \
247 check_trace_callback_type_##name(void (*cb)(data_proto)) \
248 { \
249 } \
250 static inline bool \
251 trace_##name##_enabled(void) \
252 { \
253 return static_key_false(&__tracepoint_##name.key); \
254 }
256 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
257 #define __TRACEPOINT_ENTRY(name) \
258 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \
259 " .balign 4 \n" \
260 " .long __tracepoint_" #name " - . \n" \
261 " .previous \n")
262 #else
263 #define __TRACEPOINT_ENTRY(name) \
264 static struct tracepoint * const __tracepoint_ptr_##name __used \
265 __attribute__((section("__tracepoints_ptrs"))) = \
266 &__tracepoint_##name
267 #endif
269 /*
270 * We have no guarantee that gcc and the linker won't up-align the tracepoint
271 * structures, so we create an array of pointers that will be used for iteration
272 * on the tracepoints.
273 */
274 #define DEFINE_TRACE_FN(name, reg, unreg) \
275 static const char __tpstrtab_##name[] \
276 __attribute__((section("__tracepoints_strings"))) = #name; \
277 struct tracepoint __tracepoint_##name \
278 __attribute__((section("__tracepoints"), used)) = \
279 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
280 __TRACEPOINT_ENTRY(name);
282 #define DEFINE_TRACE(name) \
283 DEFINE_TRACE_FN(name, NULL, NULL);
285 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
286 EXPORT_SYMBOL_GPL(__tracepoint_##name)
287 #define EXPORT_TRACEPOINT_SYMBOL(name) \
288 EXPORT_SYMBOL(__tracepoint_##name)
290 #else /* !TRACEPOINTS_ENABLED */
291 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
292 static inline void trace_##name(proto) \
293 { } \
294 static inline void trace_##name##_rcuidle(proto) \
295 { } \
296 static inline int \
297 register_trace_##name(void (*probe)(data_proto), \
298 void *data) \
299 { \
300 return -ENOSYS; \
301 } \
302 static inline int \
303 unregister_trace_##name(void (*probe)(data_proto), \
304 void *data) \
305 { \
306 return -ENOSYS; \
307 } \
308 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
309 { \
310 } \
311 static inline bool \
312 trace_##name##_enabled(void) \
313 { \
314 return false; \
315 }
317 #define DEFINE_TRACE_FN(name, reg, unreg)
318 #define DEFINE_TRACE(name)
319 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
320 #define EXPORT_TRACEPOINT_SYMBOL(name)
322 #endif /* TRACEPOINTS_ENABLED */
324 #ifdef CONFIG_TRACING
325 /**
326 * tracepoint_string - register constant persistent string to trace system
327 * @str - a constant persistent string that will be referenced in tracepoints
328 *
329 * If constant strings are being used in tracepoints, it is faster and
330 * more efficient to just save the pointer to the string and reference
331 * that with a printf "%s" instead of saving the string in the ring buffer
332 * and wasting space and time.
333 *
334 * The problem with the above approach is that userspace tools that read
335 * the binary output of the trace buffers do not have access to the string.
336 * Instead they just show the address of the string which is not very
337 * useful to users.
338 *
339 * With tracepoint_string(), the string will be registered to the tracing
340 * system and exported to userspace via the debugfs/tracing/printk_formats
341 * file that maps the string address to the string text. This way userspace
342 * tools that read the binary buffers have a way to map the pointers to
343 * the ASCII strings they represent.
344 *
345 * The @str used must be a constant string and persistent as it would not
346 * make sense to show a string that no longer exists. But it is still fine
347 * to be used with modules, because when modules are unloaded, if they
348 * had tracepoints, the ring buffers are cleared too. As long as the string
349 * does not change during the life of the module, it is fine to use
350 * tracepoint_string() within a module.
351 */
352 #define tracepoint_string(str) \
353 ({ \
354 static const char *___tp_str __tracepoint_string = str; \
355 ___tp_str; \
356 })
357 #define __tracepoint_string __attribute__((section("__tracepoint_str")))
358 #else
359 /*
360 * tracepoint_string() is used to save the string address for userspace
361 * tracing tools. When tracing isn't configured, there's no need to save
362 * anything.
363 */
364 # define tracepoint_string(str) str
365 # define __tracepoint_string
366 #endif
368 /*
369 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
370 * (void). "void" is a special value in a function prototype and can
371 * not be combined with other arguments. Since the DECLARE_TRACE()
372 * macro adds a data element at the beginning of the prototype,
373 * we need a way to differentiate "(void *data, proto)" from
374 * "(void *data, void)". The second prototype is invalid.
375 *
376 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
377 * and "void *__data" as the callback prototype.
378 *
379 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
380 * "void *__data, proto" as the callback prototype.
381 */
382 #define DECLARE_TRACE_NOARGS(name) \
383 __DECLARE_TRACE(name, void, , \
384 cpu_online(raw_smp_processor_id()), \
385 void *__data, __data)
387 #define DECLARE_TRACE(name, proto, args) \
388 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
389 cpu_online(raw_smp_processor_id()), \
390 PARAMS(void *__data, proto), \
391 PARAMS(__data, args))
393 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
394 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
395 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
396 PARAMS(void *__data, proto), \
397 PARAMS(__data, args))
399 #define TRACE_EVENT_FLAGS(event, flag)
401 #define TRACE_EVENT_PERF_PERM(event, expr...)
403 #endif /* DECLARE_TRACE */
405 #ifndef TRACE_EVENT
406 /*
407 * For use with the TRACE_EVENT macro:
408 *
409 * We define a tracepoint, its arguments, its printk format
410 * and its 'fast binary record' layout.
411 *
412 * Firstly, name your tracepoint via TRACE_EVENT(name : the
413 * 'subsystem_event' notation is fine.
414 *
415 * Think about this whole construct as the
416 * 'trace_sched_switch() function' from now on.
417 *
418 *
419 * TRACE_EVENT(sched_switch,
420 *
421 * *
422 * * A function has a regular function arguments
423 * * prototype, declare it via TP_PROTO():
424 * *
425 *
426 * TP_PROTO(struct rq *rq, struct task_struct *prev,
427 * struct task_struct *next),
428 *
429 * *
430 * * Define the call signature of the 'function'.
431 * * (Design sidenote: we use this instead of a
432 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
433 * *
434 *
435 * TP_ARGS(rq, prev, next),
436 *
437 * *
438 * * Fast binary tracing: define the trace record via
439 * * TP_STRUCT__entry(). You can think about it like a
440 * * regular C structure local variable definition.
441 * *
442 * * This is how the trace record is structured and will
443 * * be saved into the ring buffer. These are the fields
444 * * that will be exposed to user-space in
445 * * /sys/kernel/debug/tracing/events/<*>/format.
446 * *
447 * * The declared 'local variable' is called '__entry'
448 * *
449 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
450 * *
451 * * pid_t prev_pid;
452 * *
453 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
454 * *
455 * * char prev_comm[TASK_COMM_LEN];
456 * *
457 *
458 * TP_STRUCT__entry(
459 * __array( char, prev_comm, TASK_COMM_LEN )
460 * __field( pid_t, prev_pid )
461 * __field( int, prev_prio )
462 * __array( char, next_comm, TASK_COMM_LEN )
463 * __field( pid_t, next_pid )
464 * __field( int, next_prio )
465 * ),
466 *
467 * *
468 * * Assign the entry into the trace record, by embedding
469 * * a full C statement block into TP_fast_assign(). You
470 * * can refer to the trace record as '__entry' -
471 * * otherwise you can put arbitrary C code in here.
472 * *
473 * * Note: this C code will execute every time a trace event
474 * * happens, on an active tracepoint.
475 * *
476 *
477 * TP_fast_assign(
478 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
479 * __entry->prev_pid = prev->pid;
480 * __entry->prev_prio = prev->prio;
481 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
482 * __entry->next_pid = next->pid;
483 * __entry->next_prio = next->prio;
484 * ),
485 *
486 * *
487 * * Formatted output of a trace record via TP_printk().
488 * * This is how the tracepoint will appear under ftrace
489 * * plugins that make use of this tracepoint.
490 * *
491 * * (raw-binary tracing wont actually perform this step.)
492 * *
493 *
494 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
495 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
496 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
497 *
498 * );
499 *
500 * This macro construct is thus used for the regular printk format
501 * tracing setup, it is used to construct a function pointer based
502 * tracepoint callback (this is used by programmatic plugins and
503 * can also by used by generic instrumentation like SystemTap), and
504 * it is also used to expose a structured trace record in
505 * /sys/kernel/debug/tracing/events/.
506 *
507 * A set of (un)registration functions can be passed to the variant
508 * TRACE_EVENT_FN to perform any (un)registration work.
509 */
511 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
512 #define DEFINE_EVENT(template, name, proto, args) \
513 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
514 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
515 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
516 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
517 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
518 #define DEFINE_EVENT_CONDITION(template, name, proto, \
519 args, cond) \
520 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
521 PARAMS(args), PARAMS(cond))
523 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
524 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
525 #define TRACE_EVENT_FN(name, proto, args, struct, \
526 assign, print, reg, unreg) \
527 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
528 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
529 assign, print, reg, unreg) \
530 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
531 PARAMS(args), PARAMS(cond))
532 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
533 struct, assign, print) \
534 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
535 PARAMS(args), PARAMS(cond))
537 #define TRACE_EVENT_FLAGS(event, flag)
539 #define TRACE_EVENT_PERF_PERM(event, expr...)
541 #endif /* ifdef TRACE_EVENT (see note above) */