1 #ifndef _LINUX_TRACEPOINT_H
2 #define _LINUX_TRACEPOINT_H
3
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 */
16
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>
24
25 struct module;
26 struct tracepoint;
27 struct notifier_block;
28
29 struct trace_eval_map {
30 const char *system;
31 const char *eval_string;
32 unsigned long eval_value;
33 };
34
35 #define TRACEPOINT_DEFAULT_PRIO 10
36
37 extern struct srcu_struct tracepoint_srcu;
38
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);
49
50 #ifdef CONFIG_MODULES
51 struct tp_module {
52 struct list_head list;
53 struct module *mod;
54 };
55
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
trace_module_has_bad_taint(struct module * mod)60 static inline bool trace_module_has_bad_taint(struct module *mod)
61 {
62 return false;
63 }
64 static inline
register_tracepoint_module_notifier(struct notifier_block * nb)65 int register_tracepoint_module_notifier(struct notifier_block *nb)
66 {
67 return 0;
68 }
69 static inline
unregister_tracepoint_module_notifier(struct notifier_block * nb)70 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
71 {
72 return 0;
73 }
74 #endif /* CONFIG_MODULES */
75
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
tracepoint_synchronize_unregister(void)82 static inline void tracepoint_synchronize_unregister(void)
83 {
84 synchronize_srcu(&tracepoint_srcu);
85 synchronize_sched();
86 }
87 #else
tracepoint_synchronize_unregister(void)88 static inline void tracepoint_synchronize_unregister(void)
89 { }
90 #endif
91
92 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
93 extern int syscall_regfunc(void);
94 extern void syscall_unregfunc(void);
95 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
96
97 #define PARAMS(args...) args
98
99 #define TRACE_DEFINE_ENUM(x)
100 #define TRACE_DEFINE_SIZEOF(x)
101
102 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
tracepoint_ptr_deref(tracepoint_ptr_t * p)103 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
104 {
105 return offset_to_ptr(p);
106 }
107
108 #define __TRACEPOINT_ENTRY(name) \
109 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \
110 " .balign 4 \n" \
111 " .long __tracepoint_" #name " - . \n" \
112 " .previous \n")
113 #else
tracepoint_ptr_deref(tracepoint_ptr_t * p)114 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
115 {
116 return *p;
117 }
118
119 #define __TRACEPOINT_ENTRY(name) \
120 static tracepoint_ptr_t __tracepoint_ptr_##name __used \
121 __attribute__((section("__tracepoints_ptrs"))) = \
122 &__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 /*
155 * it_func[0] is never NULL because there is at least one element in the array
156 * when the array itself is non NULL.
157 *
158 * Note, the proto and args passed in includes "__data" as the first parameter.
159 * The reason for this is to handle the "void" prototype. If a tracepoint
160 * has a "void" prototype, then it is invalid to declare a function
161 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
162 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
163 */
164 #define __DO_TRACE(tp, proto, args, cond, rcuidle) \
165 do { \
166 struct tracepoint_func *it_func_ptr; \
167 void *it_func; \
168 void *__data; \
169 int __maybe_unused idx = 0; \
170 \
171 if (!(cond)) \
172 return; \
173 \
174 /* srcu can't be used from NMI */ \
175 WARN_ON_ONCE(rcuidle && in_nmi()); \
176 \
177 /* keep srcu and sched-rcu usage consistent */ \
178 preempt_disable_notrace(); \
179 \
180 /* \
181 * For rcuidle callers, use srcu since sched-rcu \
182 * doesn't work from the idle path. \
183 */ \
184 if (rcuidle) { \
185 idx = srcu_read_lock_notrace(&tracepoint_srcu); \
186 rcu_irq_enter_irqson(); \
187 } \
188 \
189 it_func_ptr = rcu_dereference_raw((tp)->funcs); \
190 \
191 if (it_func_ptr) { \
192 do { \
193 it_func = (it_func_ptr)->func; \
194 __data = (it_func_ptr)->data; \
195 ((void(*)(proto))(it_func))(args); \
196 } while ((++it_func_ptr)->func); \
197 } \
198 \
199 if (rcuidle) { \
200 rcu_irq_exit_irqson(); \
201 srcu_read_unlock_notrace(&tracepoint_srcu, idx);\
202 } \
203 \
204 preempt_enable_notrace(); \
205 } while (0)
206
207 #ifndef MODULE
208 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
209 static inline void trace_##name##_rcuidle(proto) \
210 { \
211 if (static_key_false(&__tracepoint_##name.key)) \
212 __DO_TRACE(&__tracepoint_##name, \
213 TP_PROTO(data_proto), \
214 TP_ARGS(data_args), \
215 TP_CONDITION(cond), 1); \
216 }
217 #else
218 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
219 #endif
220
221 /*
222 * Make sure the alignment of the structure in the __tracepoints section will
223 * not add unwanted padding between the beginning of the section and the
224 * structure. Force alignment to the same alignment as the section start.
225 *
226 * When lockdep is enabled, we make sure to always do the RCU portions of
227 * the tracepoint code, regardless of whether tracing is on. However,
228 * don't check if the condition is false, due to interaction with idle
229 * instrumentation. This lets us find RCU issues triggered with tracepoints
230 * even when this tracepoint is off. This code has no purpose other than
231 * poking RCU a bit.
232 */
233 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
234 extern struct tracepoint __tracepoint_##name; \
235 static inline void trace_##name(proto) \
236 { \
237 if (static_key_false(&__tracepoint_##name.key)) \
238 __DO_TRACE(&__tracepoint_##name, \
239 TP_PROTO(data_proto), \
240 TP_ARGS(data_args), \
241 TP_CONDITION(cond), 0); \
242 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
243 rcu_read_lock_sched_notrace(); \
244 rcu_dereference_sched(__tracepoint_##name.funcs);\
245 rcu_read_unlock_sched_notrace(); \
246 } \
247 } \
248 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
249 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
250 static inline int \
251 register_trace_##name(void (*probe)(data_proto), void *data) \
252 { \
253 return tracepoint_probe_register(&__tracepoint_##name, \
254 (void *)probe, data); \
255 } \
256 static inline int \
257 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
258 int prio) \
259 { \
260 return tracepoint_probe_register_prio(&__tracepoint_##name, \
261 (void *)probe, data, prio); \
262 } \
263 static inline int \
264 unregister_trace_##name(void (*probe)(data_proto), void *data) \
265 { \
266 return tracepoint_probe_unregister(&__tracepoint_##name,\
267 (void *)probe, data); \
268 } \
269 static inline void \
270 check_trace_callback_type_##name(void (*cb)(data_proto)) \
271 { \
272 } \
273 static inline bool \
274 trace_##name##_enabled(void) \
275 { \
276 return static_key_false(&__tracepoint_##name.key); \
277 }
278
279 /*
280 * We have no guarantee that gcc and the linker won't up-align the tracepoint
281 * structures, so we create an array of pointers that will be used for iteration
282 * on the tracepoints.
283 */
284 #define DEFINE_TRACE_FN(name, reg, unreg) \
285 static const char __tpstrtab_##name[] \
286 __attribute__((section("__tracepoints_strings"))) = #name; \
287 struct tracepoint __tracepoint_##name \
288 __attribute__((section("__tracepoints"), used)) = \
289 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
290 __TRACEPOINT_ENTRY(name);
291
292 #define DEFINE_TRACE(name) \
293 DEFINE_TRACE_FN(name, NULL, NULL);
294
295 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
296 EXPORT_SYMBOL_GPL(__tracepoint_##name)
297 #define EXPORT_TRACEPOINT_SYMBOL(name) \
298 EXPORT_SYMBOL(__tracepoint_##name)
299
300 #else /* !TRACEPOINTS_ENABLED */
301 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
302 static inline void trace_##name(proto) \
303 { } \
304 static inline void trace_##name##_rcuidle(proto) \
305 { } \
306 static inline int \
307 register_trace_##name(void (*probe)(data_proto), \
308 void *data) \
309 { \
310 return -ENOSYS; \
311 } \
312 static inline int \
313 unregister_trace_##name(void (*probe)(data_proto), \
314 void *data) \
315 { \
316 return -ENOSYS; \
317 } \
318 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
319 { \
320 } \
321 static inline bool \
322 trace_##name##_enabled(void) \
323 { \
324 return false; \
325 }
326
327 #define DEFINE_TRACE_FN(name, reg, unreg)
328 #define DEFINE_TRACE(name)
329 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
330 #define EXPORT_TRACEPOINT_SYMBOL(name)
331
332 #endif /* TRACEPOINTS_ENABLED */
333
334 #ifdef CONFIG_TRACING
335 /**
336 * tracepoint_string - register constant persistent string to trace system
337 * @str - a constant persistent string that will be referenced in tracepoints
338 *
339 * If constant strings are being used in tracepoints, it is faster and
340 * more efficient to just save the pointer to the string and reference
341 * that with a printf "%s" instead of saving the string in the ring buffer
342 * and wasting space and time.
343 *
344 * The problem with the above approach is that userspace tools that read
345 * the binary output of the trace buffers do not have access to the string.
346 * Instead they just show the address of the string which is not very
347 * useful to users.
348 *
349 * With tracepoint_string(), the string will be registered to the tracing
350 * system and exported to userspace via the debugfs/tracing/printk_formats
351 * file that maps the string address to the string text. This way userspace
352 * tools that read the binary buffers have a way to map the pointers to
353 * the ASCII strings they represent.
354 *
355 * The @str used must be a constant string and persistent as it would not
356 * make sense to show a string that no longer exists. But it is still fine
357 * to be used with modules, because when modules are unloaded, if they
358 * had tracepoints, the ring buffers are cleared too. As long as the string
359 * does not change during the life of the module, it is fine to use
360 * tracepoint_string() within a module.
361 */
362 #define tracepoint_string(str) \
363 ({ \
364 static const char *___tp_str __tracepoint_string = str; \
365 ___tp_str; \
366 })
367 #define __tracepoint_string __attribute__((section("__tracepoint_str")))
368 #else
369 /*
370 * tracepoint_string() is used to save the string address for userspace
371 * tracing tools. When tracing isn't configured, there's no need to save
372 * anything.
373 */
374 # define tracepoint_string(str) str
375 # define __tracepoint_string
376 #endif
377
378 /*
379 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
380 * (void). "void" is a special value in a function prototype and can
381 * not be combined with other arguments. Since the DECLARE_TRACE()
382 * macro adds a data element at the beginning of the prototype,
383 * we need a way to differentiate "(void *data, proto)" from
384 * "(void *data, void)". The second prototype is invalid.
385 *
386 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
387 * and "void *__data" as the callback prototype.
388 *
389 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
390 * "void *__data, proto" as the callback prototype.
391 */
392 #define DECLARE_TRACE_NOARGS(name) \
393 __DECLARE_TRACE(name, void, , \
394 cpu_online(raw_smp_processor_id()), \
395 void *__data, __data)
396
397 #define DECLARE_TRACE(name, proto, args) \
398 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
399 cpu_online(raw_smp_processor_id()), \
400 PARAMS(void *__data, proto), \
401 PARAMS(__data, args))
402
403 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
404 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
405 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
406 PARAMS(void *__data, proto), \
407 PARAMS(__data, args))
408
409 #define TRACE_EVENT_FLAGS(event, flag)
410
411 #define TRACE_EVENT_PERF_PERM(event, expr...)
412
413 #endif /* DECLARE_TRACE */
414
415 #ifndef TRACE_EVENT
416 /*
417 * For use with the TRACE_EVENT macro:
418 *
419 * We define a tracepoint, its arguments, its printk format
420 * and its 'fast binary record' layout.
421 *
422 * Firstly, name your tracepoint via TRACE_EVENT(name : the
423 * 'subsystem_event' notation is fine.
424 *
425 * Think about this whole construct as the
426 * 'trace_sched_switch() function' from now on.
427 *
428 *
429 * TRACE_EVENT(sched_switch,
430 *
431 * *
432 * * A function has a regular function arguments
433 * * prototype, declare it via TP_PROTO():
434 * *
435 *
436 * TP_PROTO(struct rq *rq, struct task_struct *prev,
437 * struct task_struct *next),
438 *
439 * *
440 * * Define the call signature of the 'function'.
441 * * (Design sidenote: we use this instead of a
442 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
443 * *
444 *
445 * TP_ARGS(rq, prev, next),
446 *
447 * *
448 * * Fast binary tracing: define the trace record via
449 * * TP_STRUCT__entry(). You can think about it like a
450 * * regular C structure local variable definition.
451 * *
452 * * This is how the trace record is structured and will
453 * * be saved into the ring buffer. These are the fields
454 * * that will be exposed to user-space in
455 * * /sys/kernel/debug/tracing/events/<*>/format.
456 * *
457 * * The declared 'local variable' is called '__entry'
458 * *
459 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
460 * *
461 * * pid_t prev_pid;
462 * *
463 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
464 * *
465 * * char prev_comm[TASK_COMM_LEN];
466 * *
467 *
468 * TP_STRUCT__entry(
469 * __array( char, prev_comm, TASK_COMM_LEN )
470 * __field( pid_t, prev_pid )
471 * __field( int, prev_prio )
472 * __array( char, next_comm, TASK_COMM_LEN )
473 * __field( pid_t, next_pid )
474 * __field( int, next_prio )
475 * ),
476 *
477 * *
478 * * Assign the entry into the trace record, by embedding
479 * * a full C statement block into TP_fast_assign(). You
480 * * can refer to the trace record as '__entry' -
481 * * otherwise you can put arbitrary C code in here.
482 * *
483 * * Note: this C code will execute every time a trace event
484 * * happens, on an active tracepoint.
485 * *
486 *
487 * TP_fast_assign(
488 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
489 * __entry->prev_pid = prev->pid;
490 * __entry->prev_prio = prev->prio;
491 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
492 * __entry->next_pid = next->pid;
493 * __entry->next_prio = next->prio;
494 * ),
495 *
496 * *
497 * * Formatted output of a trace record via TP_printk().
498 * * This is how the tracepoint will appear under ftrace
499 * * plugins that make use of this tracepoint.
500 * *
501 * * (raw-binary tracing wont actually perform this step.)
502 * *
503 *
504 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
505 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
506 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
507 *
508 * );
509 *
510 * This macro construct is thus used for the regular printk format
511 * tracing setup, it is used to construct a function pointer based
512 * tracepoint callback (this is used by programmatic plugins and
513 * can also by used by generic instrumentation like SystemTap), and
514 * it is also used to expose a structured trace record in
515 * /sys/kernel/debug/tracing/events/.
516 *
517 * A set of (un)registration functions can be passed to the variant
518 * TRACE_EVENT_FN to perform any (un)registration work.
519 */
520
521 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
522 #define DEFINE_EVENT(template, name, proto, args) \
523 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
524 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
525 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
526 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
527 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
528 #define DEFINE_EVENT_CONDITION(template, name, proto, \
529 args, cond) \
530 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
531 PARAMS(args), PARAMS(cond))
532
533 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
534 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
535 #define TRACE_EVENT_FN(name, proto, args, struct, \
536 assign, print, reg, unreg) \
537 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
538 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
539 assign, print, reg, unreg) \
540 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
541 PARAMS(args), PARAMS(cond))
542 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
543 struct, assign, print) \
544 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
545 PARAMS(args), PARAMS(cond))
546
547 #define TRACE_EVENT_FLAGS(event, flag)
548
549 #define TRACE_EVENT_PERF_PERM(event, expr...)
550
551 #endif /* ifdef TRACE_EVENT (see note above) */
552
