1 #ifndef _LINUX_TRACEPOINT_H
2 #define _LINUX_TRACEPOINT_H
3
4 /*
5 * Kernel Tracepoint API.
6 *
7 * See Documentation/trace/tracepoints.txt.
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/errno.h>
19 #include <linux/types.h>
20 #include <linux/cpumask.h>
21 #include <linux/rcupdate.h>
22 #include <linux/tracepoint-defs.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 int
37 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
38 extern int
39 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
40 int prio);
41 extern int
42 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
43 extern void
44 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
45 void *priv);
46
47 #ifdef CONFIG_MODULES
48 struct tp_module {
49 struct list_head list;
50 struct module *mod;
51 };
52
53 bool trace_module_has_bad_taint(struct module *mod);
54 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
55 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
56 #else
trace_module_has_bad_taint(struct module * mod)57 static inline bool trace_module_has_bad_taint(struct module *mod)
58 {
59 return false;
60 }
61 static inline
register_tracepoint_module_notifier(struct notifier_block * nb)62 int register_tracepoint_module_notifier(struct notifier_block *nb)
63 {
64 return 0;
65 }
66 static inline
unregister_tracepoint_module_notifier(struct notifier_block * nb)67 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
68 {
69 return 0;
70 }
71 #endif /* CONFIG_MODULES */
72
73 /*
74 * tracepoint_synchronize_unregister must be called between the last tracepoint
75 * probe unregistration and the end of module exit to make sure there is no
76 * caller executing a probe when it is freed.
77 */
tracepoint_synchronize_unregister(void)78 static inline void tracepoint_synchronize_unregister(void)
79 {
80 synchronize_sched();
81 }
82
83 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
84 extern int syscall_regfunc(void);
85 extern void syscall_unregfunc(void);
86 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
87
88 #define PARAMS(args...) args
89
90 #define TRACE_DEFINE_ENUM(x)
91 #define TRACE_DEFINE_SIZEOF(x)
92
93 #endif /* _LINUX_TRACEPOINT_H */
94
95 /*
96 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
97 * file ifdef protection.
98 * This is due to the way trace events work. If a file includes two
99 * trace event headers under one "CREATE_TRACE_POINTS" the first include
100 * will override the TRACE_EVENT and break the second include.
101 */
102
103 #ifndef DECLARE_TRACE
104
105 #define TP_PROTO(args...) args
106 #define TP_ARGS(args...) args
107 #define TP_CONDITION(args...) args
108
109 /*
110 * Individual subsystem my have a separate configuration to
111 * enable their tracepoints. By default, this file will create
112 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
113 * wants to be able to disable its tracepoints from being created
114 * it can define NOTRACE before including the tracepoint headers.
115 */
116 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
117 #define TRACEPOINTS_ENABLED
118 #endif
119
120 #ifdef TRACEPOINTS_ENABLED
121
122 /*
123 * it_func[0] is never NULL because there is at least one element in the array
124 * when the array itself is non NULL.
125 *
126 * Note, the proto and args passed in includes "__data" as the first parameter.
127 * The reason for this is to handle the "void" prototype. If a tracepoint
128 * has a "void" prototype, then it is invalid to declare a function
129 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
130 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
131 */
132 #define __DO_TRACE(tp, proto, args, cond, rcucheck) \
133 do { \
134 struct tracepoint_func *it_func_ptr; \
135 void *it_func; \
136 void *__data; \
137 \
138 if (!(cond)) \
139 return; \
140 if (rcucheck) { \
141 if (WARN_ON_ONCE(rcu_irq_enter_disabled())) \
142 return; \
143 rcu_irq_enter_irqson(); \
144 } \
145 rcu_read_lock_sched_notrace(); \
146 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
147 if (it_func_ptr) { \
148 do { \
149 it_func = (it_func_ptr)->func; \
150 __data = (it_func_ptr)->data; \
151 ((void(*)(proto))(it_func))(args); \
152 } while ((++it_func_ptr)->func); \
153 } \
154 rcu_read_unlock_sched_notrace(); \
155 if (rcucheck) \
156 rcu_irq_exit_irqson(); \
157 } while (0)
158
159 #ifndef MODULE
160 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
161 static inline void trace_##name##_rcuidle(proto) \
162 { \
163 if (static_key_false(&__tracepoint_##name.key)) \
164 __DO_TRACE(&__tracepoint_##name, \
165 TP_PROTO(data_proto), \
166 TP_ARGS(data_args), \
167 TP_CONDITION(cond), 1); \
168 }
169 #else
170 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
171 #endif
172
173 /*
174 * Make sure the alignment of the structure in the __tracepoints section will
175 * not add unwanted padding between the beginning of the section and the
176 * structure. Force alignment to the same alignment as the section start.
177 *
178 * When lockdep is enabled, we make sure to always do the RCU portions of
179 * the tracepoint code, regardless of whether tracing is on. However,
180 * don't check if the condition is false, due to interaction with idle
181 * instrumentation. This lets us find RCU issues triggered with tracepoints
182 * even when this tracepoint is off. This code has no purpose other than
183 * poking RCU a bit.
184 */
185 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
186 extern struct tracepoint __tracepoint_##name; \
187 static inline void trace_##name(proto) \
188 { \
189 if (static_key_false(&__tracepoint_##name.key)) \
190 __DO_TRACE(&__tracepoint_##name, \
191 TP_PROTO(data_proto), \
192 TP_ARGS(data_args), \
193 TP_CONDITION(cond), 0); \
194 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
195 rcu_read_lock_sched_notrace(); \
196 rcu_dereference_sched(__tracepoint_##name.funcs);\
197 rcu_read_unlock_sched_notrace(); \
198 } \
199 } \
200 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
201 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
202 static inline int \
203 register_trace_##name(void (*probe)(data_proto), void *data) \
204 { \
205 return tracepoint_probe_register(&__tracepoint_##name, \
206 (void *)probe, data); \
207 } \
208 static inline int \
209 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
210 int prio) \
211 { \
212 return tracepoint_probe_register_prio(&__tracepoint_##name, \
213 (void *)probe, data, prio); \
214 } \
215 static inline int \
216 unregister_trace_##name(void (*probe)(data_proto), void *data) \
217 { \
218 return tracepoint_probe_unregister(&__tracepoint_##name,\
219 (void *)probe, data); \
220 } \
221 static inline void \
222 check_trace_callback_type_##name(void (*cb)(data_proto)) \
223 { \
224 } \
225 static inline bool \
226 trace_##name##_enabled(void) \
227 { \
228 return static_key_false(&__tracepoint_##name.key); \
229 }
230
231 /*
232 * We have no guarantee that gcc and the linker won't up-align the tracepoint
233 * structures, so we create an array of pointers that will be used for iteration
234 * on the tracepoints.
235 */
236 #define DEFINE_TRACE_FN(name, reg, unreg) \
237 static const char __tpstrtab_##name[] \
238 __attribute__((section("__tracepoints_strings"))) = #name; \
239 struct tracepoint __tracepoint_##name \
240 __attribute__((section("__tracepoints"))) = \
241 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
242 static struct tracepoint * const __tracepoint_ptr_##name __used \
243 __attribute__((section("__tracepoints_ptrs"))) = \
244 &__tracepoint_##name;
245
246 #define DEFINE_TRACE(name) \
247 DEFINE_TRACE_FN(name, NULL, NULL);
248
249 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
250 EXPORT_SYMBOL_GPL(__tracepoint_##name)
251 #define EXPORT_TRACEPOINT_SYMBOL(name) \
252 EXPORT_SYMBOL(__tracepoint_##name)
253
254 #else /* !TRACEPOINTS_ENABLED */
255 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
256 static inline void trace_##name(proto) \
257 { } \
258 static inline void trace_##name##_rcuidle(proto) \
259 { } \
260 static inline int \
261 register_trace_##name(void (*probe)(data_proto), \
262 void *data) \
263 { \
264 return -ENOSYS; \
265 } \
266 static inline int \
267 unregister_trace_##name(void (*probe)(data_proto), \
268 void *data) \
269 { \
270 return -ENOSYS; \
271 } \
272 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
273 { \
274 } \
275 static inline bool \
276 trace_##name##_enabled(void) \
277 { \
278 return false; \
279 }
280
281 #define DEFINE_TRACE_FN(name, reg, unreg)
282 #define DEFINE_TRACE(name)
283 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
284 #define EXPORT_TRACEPOINT_SYMBOL(name)
285
286 #endif /* TRACEPOINTS_ENABLED */
287
288 #ifdef CONFIG_TRACING
289 /**
290 * tracepoint_string - register constant persistent string to trace system
291 * @str - a constant persistent string that will be referenced in tracepoints
292 *
293 * If constant strings are being used in tracepoints, it is faster and
294 * more efficient to just save the pointer to the string and reference
295 * that with a printf "%s" instead of saving the string in the ring buffer
296 * and wasting space and time.
297 *
298 * The problem with the above approach is that userspace tools that read
299 * the binary output of the trace buffers do not have access to the string.
300 * Instead they just show the address of the string which is not very
301 * useful to users.
302 *
303 * With tracepoint_string(), the string will be registered to the tracing
304 * system and exported to userspace via the debugfs/tracing/printk_formats
305 * file that maps the string address to the string text. This way userspace
306 * tools that read the binary buffers have a way to map the pointers to
307 * the ASCII strings they represent.
308 *
309 * The @str used must be a constant string and persistent as it would not
310 * make sense to show a string that no longer exists. But it is still fine
311 * to be used with modules, because when modules are unloaded, if they
312 * had tracepoints, the ring buffers are cleared too. As long as the string
313 * does not change during the life of the module, it is fine to use
314 * tracepoint_string() within a module.
315 */
316 #define tracepoint_string(str) \
317 ({ \
318 static const char *___tp_str __tracepoint_string = str; \
319 ___tp_str; \
320 })
321 #define __tracepoint_string __attribute__((section("__tracepoint_str")))
322 #else
323 /*
324 * tracepoint_string() is used to save the string address for userspace
325 * tracing tools. When tracing isn't configured, there's no need to save
326 * anything.
327 */
328 # define tracepoint_string(str) str
329 # define __tracepoint_string
330 #endif
331
332 /*
333 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
334 * (void). "void" is a special value in a function prototype and can
335 * not be combined with other arguments. Since the DECLARE_TRACE()
336 * macro adds a data element at the beginning of the prototype,
337 * we need a way to differentiate "(void *data, proto)" from
338 * "(void *data, void)". The second prototype is invalid.
339 *
340 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
341 * and "void *__data" as the callback prototype.
342 *
343 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
344 * "void *__data, proto" as the callback prototype.
345 */
346 #define DECLARE_TRACE_NOARGS(name) \
347 __DECLARE_TRACE(name, void, , \
348 cpu_online(raw_smp_processor_id()), \
349 void *__data, __data)
350
351 #define DECLARE_TRACE(name, proto, args) \
352 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
353 cpu_online(raw_smp_processor_id()), \
354 PARAMS(void *__data, proto), \
355 PARAMS(__data, args))
356
357 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
358 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
359 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
360 PARAMS(void *__data, proto), \
361 PARAMS(__data, args))
362
363 #define TRACE_EVENT_FLAGS(event, flag)
364
365 #define TRACE_EVENT_PERF_PERM(event, expr...)
366
367 #endif /* DECLARE_TRACE */
368
369 #ifndef TRACE_EVENT
370 /*
371 * For use with the TRACE_EVENT macro:
372 *
373 * We define a tracepoint, its arguments, its printk format
374 * and its 'fast binary record' layout.
375 *
376 * Firstly, name your tracepoint via TRACE_EVENT(name : the
377 * 'subsystem_event' notation is fine.
378 *
379 * Think about this whole construct as the
380 * 'trace_sched_switch() function' from now on.
381 *
382 *
383 * TRACE_EVENT(sched_switch,
384 *
385 * *
386 * * A function has a regular function arguments
387 * * prototype, declare it via TP_PROTO():
388 * *
389 *
390 * TP_PROTO(struct rq *rq, struct task_struct *prev,
391 * struct task_struct *next),
392 *
393 * *
394 * * Define the call signature of the 'function'.
395 * * (Design sidenote: we use this instead of a
396 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
397 * *
398 *
399 * TP_ARGS(rq, prev, next),
400 *
401 * *
402 * * Fast binary tracing: define the trace record via
403 * * TP_STRUCT__entry(). You can think about it like a
404 * * regular C structure local variable definition.
405 * *
406 * * This is how the trace record is structured and will
407 * * be saved into the ring buffer. These are the fields
408 * * that will be exposed to user-space in
409 * * /sys/kernel/debug/tracing/events/<*>/format.
410 * *
411 * * The declared 'local variable' is called '__entry'
412 * *
413 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
414 * *
415 * * pid_t prev_pid;
416 * *
417 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
418 * *
419 * * char prev_comm[TASK_COMM_LEN];
420 * *
421 *
422 * TP_STRUCT__entry(
423 * __array( char, prev_comm, TASK_COMM_LEN )
424 * __field( pid_t, prev_pid )
425 * __field( int, prev_prio )
426 * __array( char, next_comm, TASK_COMM_LEN )
427 * __field( pid_t, next_pid )
428 * __field( int, next_prio )
429 * ),
430 *
431 * *
432 * * Assign the entry into the trace record, by embedding
433 * * a full C statement block into TP_fast_assign(). You
434 * * can refer to the trace record as '__entry' -
435 * * otherwise you can put arbitrary C code in here.
436 * *
437 * * Note: this C code will execute every time a trace event
438 * * happens, on an active tracepoint.
439 * *
440 *
441 * TP_fast_assign(
442 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
443 * __entry->prev_pid = prev->pid;
444 * __entry->prev_prio = prev->prio;
445 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
446 * __entry->next_pid = next->pid;
447 * __entry->next_prio = next->prio;
448 * ),
449 *
450 * *
451 * * Formatted output of a trace record via TP_printk().
452 * * This is how the tracepoint will appear under ftrace
453 * * plugins that make use of this tracepoint.
454 * *
455 * * (raw-binary tracing wont actually perform this step.)
456 * *
457 *
458 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
459 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
460 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
461 *
462 * );
463 *
464 * This macro construct is thus used for the regular printk format
465 * tracing setup, it is used to construct a function pointer based
466 * tracepoint callback (this is used by programmatic plugins and
467 * can also by used by generic instrumentation like SystemTap), and
468 * it is also used to expose a structured trace record in
469 * /sys/kernel/debug/tracing/events/.
470 *
471 * A set of (un)registration functions can be passed to the variant
472 * TRACE_EVENT_FN to perform any (un)registration work.
473 */
474
475 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
476 #define DEFINE_EVENT(template, name, proto, args) \
477 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
478 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
479 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
480 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
481 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
482 #define DEFINE_EVENT_CONDITION(template, name, proto, \
483 args, cond) \
484 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
485 PARAMS(args), PARAMS(cond))
486
487 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
488 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
489 #define TRACE_EVENT_FN(name, proto, args, struct, \
490 assign, print, reg, unreg) \
491 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
492 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
493 assign, print, reg, unreg) \
494 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
495 PARAMS(args), PARAMS(cond))
496 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
497 struct, assign, print) \
498 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
499 PARAMS(args), PARAMS(cond))
500
501 #define TRACE_EVENT_FLAGS(event, flag)
502
503 #define TRACE_EVENT_PERF_PERM(event, expr...)
504
505 #endif /* ifdef TRACE_EVENT (see note above) */
506