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