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/static_key.h>
23
24 struct module;
25 struct tracepoint;
26 struct notifier_block;
27
28 struct tracepoint_func {
29 void *func;
30 void *data;
31 };
32
33 struct tracepoint {
34 const char *name; /* Tracepoint name */
35 struct static_key key;
36 void (*regfunc)(void);
37 void (*unregfunc)(void);
38 struct tracepoint_func __rcu *funcs;
39 };
40
41 struct trace_enum_map {
42 const char *system;
43 const char *enum_string;
44 unsigned long enum_value;
45 };
46
47 extern int
48 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
49 extern int
50 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
51 extern void
52 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
53 void *priv);
54
55 #ifdef CONFIG_MODULES
56 struct tp_module {
57 struct list_head list;
58 struct module *mod;
59 };
60
61 bool trace_module_has_bad_taint(struct module *mod);
62 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
63 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
64 #else
trace_module_has_bad_taint(struct module * mod)65 static inline bool trace_module_has_bad_taint(struct module *mod)
66 {
67 return false;
68 }
69 static inline
register_tracepoint_module_notifier(struct notifier_block * nb)70 int register_tracepoint_module_notifier(struct notifier_block *nb)
71 {
72 return 0;
73 }
74 static inline
unregister_tracepoint_module_notifier(struct notifier_block * nb)75 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
76 {
77 return 0;
78 }
79 #endif /* CONFIG_MODULES */
80
81 /*
82 * tracepoint_synchronize_unregister must be called between the last tracepoint
83 * probe unregistration and the end of module exit to make sure there is no
84 * caller executing a probe when it is freed.
85 */
tracepoint_synchronize_unregister(void)86 static inline void tracepoint_synchronize_unregister(void)
87 {
88 synchronize_sched();
89 }
90
91 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
92 extern void syscall_regfunc(void);
93 extern void syscall_unregfunc(void);
94 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
95
96 #define PARAMS(args...) args
97
98 #define TRACE_DEFINE_ENUM(x)
99
100 #endif /* _LINUX_TRACEPOINT_H */
101
102 /*
103 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
104 * file ifdef protection.
105 * This is due to the way trace events work. If a file includes two
106 * trace event headers under one "CREATE_TRACE_POINTS" the first include
107 * will override the TRACE_EVENT and break the second include.
108 */
109
110 #ifndef DECLARE_TRACE
111
112 #define TP_PROTO(args...) args
113 #define TP_ARGS(args...) args
114 #define TP_CONDITION(args...) args
115
116 #ifdef CONFIG_TRACEPOINTS
117
118 /*
119 * it_func[0] is never NULL because there is at least one element in the array
120 * when the array itself is non NULL.
121 *
122 * Note, the proto and args passed in includes "__data" as the first parameter.
123 * The reason for this is to handle the "void" prototype. If a tracepoint
124 * has a "void" prototype, then it is invalid to declare a function
125 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
126 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
127 */
128 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
129 do { \
130 struct tracepoint_func *it_func_ptr; \
131 void *it_func; \
132 void *__data; \
133 \
134 if (!(cond)) \
135 return; \
136 prercu; \
137 rcu_read_lock_sched_notrace(); \
138 it_func_ptr = rcu_dereference_sched((tp)->funcs); \
139 if (it_func_ptr) { \
140 do { \
141 it_func = (it_func_ptr)->func; \
142 __data = (it_func_ptr)->data; \
143 ((void(*)(proto))(it_func))(args); \
144 } while ((++it_func_ptr)->func); \
145 } \
146 rcu_read_unlock_sched_notrace(); \
147 postrcu; \
148 } while (0)
149
150 #ifndef MODULE
151 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
152 static inline void trace_##name##_rcuidle(proto) \
153 { \
154 if (static_key_false(&__tracepoint_##name.key)) \
155 __DO_TRACE(&__tracepoint_##name, \
156 TP_PROTO(data_proto), \
157 TP_ARGS(data_args), \
158 TP_CONDITION(cond), \
159 rcu_irq_enter(), \
160 rcu_irq_exit()); \
161 }
162 #else
163 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
164 #endif
165
166 /*
167 * Make sure the alignment of the structure in the __tracepoints section will
168 * not add unwanted padding between the beginning of the section and the
169 * structure. Force alignment to the same alignment as the section start.
170 *
171 * When lockdep is enabled, we make sure to always do the RCU portions of
172 * the tracepoint code, regardless of whether tracing is on or we match the
173 * condition. This lets us find RCU issues triggered with tracepoints even
174 * when this tracepoint is off. This code has no purpose other than poking
175 * RCU a bit.
176 */
177 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
178 extern struct tracepoint __tracepoint_##name; \
179 static inline void trace_##name(proto) \
180 { \
181 if (static_key_false(&__tracepoint_##name.key)) \
182 __DO_TRACE(&__tracepoint_##name, \
183 TP_PROTO(data_proto), \
184 TP_ARGS(data_args), \
185 TP_CONDITION(cond),,); \
186 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
187 rcu_read_lock_sched_notrace(); \
188 rcu_dereference_sched(__tracepoint_##name.funcs);\
189 rcu_read_unlock_sched_notrace(); \
190 } \
191 } \
192 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
193 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
194 static inline int \
195 register_trace_##name(void (*probe)(data_proto), void *data) \
196 { \
197 return tracepoint_probe_register(&__tracepoint_##name, \
198 (void *)probe, data); \
199 } \
200 static inline int \
201 unregister_trace_##name(void (*probe)(data_proto), void *data) \
202 { \
203 return tracepoint_probe_unregister(&__tracepoint_##name,\
204 (void *)probe, data); \
205 } \
206 static inline void \
207 check_trace_callback_type_##name(void (*cb)(data_proto)) \
208 { \
209 } \
210 static inline bool \
211 trace_##name##_enabled(void) \
212 { \
213 return static_key_false(&__tracepoint_##name.key); \
214 }
215
216 /*
217 * We have no guarantee that gcc and the linker won't up-align the tracepoint
218 * structures, so we create an array of pointers that will be used for iteration
219 * on the tracepoints.
220 */
221 #define DEFINE_TRACE_FN(name, reg, unreg) \
222 static const char __tpstrtab_##name[] \
223 __attribute__((section("__tracepoints_strings"))) = #name; \
224 struct tracepoint __tracepoint_##name \
225 __attribute__((section("__tracepoints"))) = \
226 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
227 static struct tracepoint * const __tracepoint_ptr_##name __used \
228 __attribute__((section("__tracepoints_ptrs"))) = \
229 &__tracepoint_##name;
230
231 #define DEFINE_TRACE(name) \
232 DEFINE_TRACE_FN(name, NULL, NULL);
233
234 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
235 EXPORT_SYMBOL_GPL(__tracepoint_##name)
236 #define EXPORT_TRACEPOINT_SYMBOL(name) \
237 EXPORT_SYMBOL(__tracepoint_##name)
238
239 #else /* !CONFIG_TRACEPOINTS */
240 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
241 static inline void trace_##name(proto) \
242 { } \
243 static inline void trace_##name##_rcuidle(proto) \
244 { } \
245 static inline int \
246 register_trace_##name(void (*probe)(data_proto), \
247 void *data) \
248 { \
249 return -ENOSYS; \
250 } \
251 static inline int \
252 unregister_trace_##name(void (*probe)(data_proto), \
253 void *data) \
254 { \
255 return -ENOSYS; \
256 } \
257 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
258 { \
259 } \
260 static inline bool \
261 trace_##name##_enabled(void) \
262 { \
263 return false; \
264 }
265
266 #define DEFINE_TRACE_FN(name, reg, unreg)
267 #define DEFINE_TRACE(name)
268 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
269 #define EXPORT_TRACEPOINT_SYMBOL(name)
270
271 #endif /* CONFIG_TRACEPOINTS */
272
273 #ifdef CONFIG_TRACING
274 /**
275 * tracepoint_string - register constant persistent string to trace system
276 * @str - a constant persistent string that will be referenced in tracepoints
277 *
278 * If constant strings are being used in tracepoints, it is faster and
279 * more efficient to just save the pointer to the string and reference
280 * that with a printf "%s" instead of saving the string in the ring buffer
281 * and wasting space and time.
282 *
283 * The problem with the above approach is that userspace tools that read
284 * the binary output of the trace buffers do not have access to the string.
285 * Instead they just show the address of the string which is not very
286 * useful to users.
287 *
288 * With tracepoint_string(), the string will be registered to the tracing
289 * system and exported to userspace via the debugfs/tracing/printk_formats
290 * file that maps the string address to the string text. This way userspace
291 * tools that read the binary buffers have a way to map the pointers to
292 * the ASCII strings they represent.
293 *
294 * The @str used must be a constant string and persistent as it would not
295 * make sense to show a string that no longer exists. But it is still fine
296 * to be used with modules, because when modules are unloaded, if they
297 * had tracepoints, the ring buffers are cleared too. As long as the string
298 * does not change during the life of the module, it is fine to use
299 * tracepoint_string() within a module.
300 */
301 #define tracepoint_string(str) \
302 ({ \
303 static const char *___tp_str __tracepoint_string = str; \
304 ___tp_str; \
305 })
306 #define __tracepoint_string __attribute__((section("__tracepoint_str")))
307 #else
308 /*
309 * tracepoint_string() is used to save the string address for userspace
310 * tracing tools. When tracing isn't configured, there's no need to save
311 * anything.
312 */
313 # define tracepoint_string(str) str
314 # define __tracepoint_string
315 #endif
316
317 /*
318 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
319 * (void). "void" is a special value in a function prototype and can
320 * not be combined with other arguments. Since the DECLARE_TRACE()
321 * macro adds a data element at the beginning of the prototype,
322 * we need a way to differentiate "(void *data, proto)" from
323 * "(void *data, void)". The second prototype is invalid.
324 *
325 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
326 * and "void *__data" as the callback prototype.
327 *
328 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
329 * "void *__data, proto" as the callback prototype.
330 */
331 #define DECLARE_TRACE_NOARGS(name) \
332 __DECLARE_TRACE(name, void, , \
333 cpu_online(raw_smp_processor_id()), \
334 void *__data, __data)
335
336 #define DECLARE_TRACE(name, proto, args) \
337 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
338 cpu_online(raw_smp_processor_id()), \
339 PARAMS(void *__data, proto), \
340 PARAMS(__data, args))
341
342 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
343 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
344 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
345 PARAMS(void *__data, proto), \
346 PARAMS(__data, args))
347
348 #define TRACE_EVENT_FLAGS(event, flag)
349
350 #define TRACE_EVENT_PERF_PERM(event, expr...)
351
352 #endif /* DECLARE_TRACE */
353
354 #ifndef TRACE_EVENT
355 /*
356 * For use with the TRACE_EVENT macro:
357 *
358 * We define a tracepoint, its arguments, its printk format
359 * and its 'fast binary record' layout.
360 *
361 * Firstly, name your tracepoint via TRACE_EVENT(name : the
362 * 'subsystem_event' notation is fine.
363 *
364 * Think about this whole construct as the
365 * 'trace_sched_switch() function' from now on.
366 *
367 *
368 * TRACE_EVENT(sched_switch,
369 *
370 * *
371 * * A function has a regular function arguments
372 * * prototype, declare it via TP_PROTO():
373 * *
374 *
375 * TP_PROTO(struct rq *rq, struct task_struct *prev,
376 * struct task_struct *next),
377 *
378 * *
379 * * Define the call signature of the 'function'.
380 * * (Design sidenote: we use this instead of a
381 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
382 * *
383 *
384 * TP_ARGS(rq, prev, next),
385 *
386 * *
387 * * Fast binary tracing: define the trace record via
388 * * TP_STRUCT__entry(). You can think about it like a
389 * * regular C structure local variable definition.
390 * *
391 * * This is how the trace record is structured and will
392 * * be saved into the ring buffer. These are the fields
393 * * that will be exposed to user-space in
394 * * /sys/kernel/debug/tracing/events/<*>/format.
395 * *
396 * * The declared 'local variable' is called '__entry'
397 * *
398 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
399 * *
400 * * pid_t prev_pid;
401 * *
402 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
403 * *
404 * * char prev_comm[TASK_COMM_LEN];
405 * *
406 *
407 * TP_STRUCT__entry(
408 * __array( char, prev_comm, TASK_COMM_LEN )
409 * __field( pid_t, prev_pid )
410 * __field( int, prev_prio )
411 * __array( char, next_comm, TASK_COMM_LEN )
412 * __field( pid_t, next_pid )
413 * __field( int, next_prio )
414 * ),
415 *
416 * *
417 * * Assign the entry into the trace record, by embedding
418 * * a full C statement block into TP_fast_assign(). You
419 * * can refer to the trace record as '__entry' -
420 * * otherwise you can put arbitrary C code in here.
421 * *
422 * * Note: this C code will execute every time a trace event
423 * * happens, on an active tracepoint.
424 * *
425 *
426 * TP_fast_assign(
427 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
428 * __entry->prev_pid = prev->pid;
429 * __entry->prev_prio = prev->prio;
430 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
431 * __entry->next_pid = next->pid;
432 * __entry->next_prio = next->prio;
433 * ),
434 *
435 * *
436 * * Formatted output of a trace record via TP_printk().
437 * * This is how the tracepoint will appear under ftrace
438 * * plugins that make use of this tracepoint.
439 * *
440 * * (raw-binary tracing wont actually perform this step.)
441 * *
442 *
443 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
444 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
445 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
446 *
447 * );
448 *
449 * This macro construct is thus used for the regular printk format
450 * tracing setup, it is used to construct a function pointer based
451 * tracepoint callback (this is used by programmatic plugins and
452 * can also by used by generic instrumentation like SystemTap), and
453 * it is also used to expose a structured trace record in
454 * /sys/kernel/debug/tracing/events/.
455 *
456 * A set of (un)registration functions can be passed to the variant
457 * TRACE_EVENT_FN to perform any (un)registration work.
458 */
459
460 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
461 #define DEFINE_EVENT(template, name, proto, args) \
462 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
463 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
464 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
465 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
466 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
467 #define DEFINE_EVENT_CONDITION(template, name, proto, \
468 args, cond) \
469 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
470 PARAMS(args), PARAMS(cond))
471
472 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
473 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
474 #define TRACE_EVENT_FN(name, proto, args, struct, \
475 assign, print, reg, unreg) \
476 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
477 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
478 struct, assign, print) \
479 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
480 PARAMS(args), PARAMS(cond))
481
482 #define TRACE_EVENT_FLAGS(event, flag)
483
484 #define TRACE_EVENT_PERF_PERM(event, expr...)
485
486 #endif /* ifdef TRACE_EVENT (see note above) */
487