1 #ifndef _LINUX_TRACEPOINT_H
2 #define _LINUX_TRACEPOINT_H
5 * Kernel Tracepoint API.
7 * See Documentation/trace/tracepoints.rst.
9 * Copyright (C) 2008-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
11 * Heavily inspired from the Linux Kernel Markers.
13 * This file is released under the GPLv2.
14 * See the file COPYING for more details.
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>
27 struct notifier_block;
29 struct trace_eval_map {
31 const char *eval_string;
32 unsigned long eval_value;
35 #define TRACEPOINT_DEFAULT_PRIO 10
37 extern struct srcu_struct tracepoint_srcu;
40 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
42 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
45 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
47 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
52 struct list_head list;
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);
60 static inline bool trace_module_has_bad_taint(struct module *mod)
65 int register_tracepoint_module_notifier(struct notifier_block *nb)
70 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
74 #endif /* CONFIG_MODULES */
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.
81 #ifdef CONFIG_TRACEPOINTS
82 static inline void tracepoint_synchronize_unregister(void)
84 synchronize_srcu(&tracepoint_srcu);
88 static inline void tracepoint_synchronize_unregister(void)
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 */
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.
112 #ifndef DECLARE_TRACE
114 #define TP_PROTO(args...) args
115 #define TP_ARGS(args...) args
116 #define TP_CONDITION(args...) args
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.
125 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
126 #define TRACEPOINTS_ENABLED
129 #ifdef TRACEPOINTS_ENABLED
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.
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".
141 #define __DO_TRACE(tp, proto, args, cond, rcuidle) \
143 struct tracepoint_func *it_func_ptr; \
146 int __maybe_unused idx = 0; \
151 /* srcu can't be used from NMI */ \
152 WARN_ON_ONCE(rcuidle && in_nmi()); \
154 /* keep srcu and sched-rcu usage consistent */ \
155 preempt_disable_notrace(); \
158 * For rcuidle callers, use srcu since sched-rcu \
159 * doesn't work from the idle path. \
162 idx = srcu_read_lock_notrace(&tracepoint_srcu); \
164 it_func_ptr = rcu_dereference_raw((tp)->funcs); \
168 it_func = (it_func_ptr)->func; \
169 __data = (it_func_ptr)->data; \
170 ((void(*)(proto))(it_func))(args); \
171 } while ((++it_func_ptr)->func); \
175 srcu_read_unlock_notrace(&tracepoint_srcu, idx);\
177 preempt_enable_notrace(); \
181 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
182 static inline void trace_##name##_rcuidle(proto) \
184 if (static_key_false(&__tracepoint_##name.key)) \
185 __DO_TRACE(&__tracepoint_##name, \
186 TP_PROTO(data_proto), \
187 TP_ARGS(data_args), \
188 TP_CONDITION(cond), 1); \
191 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
195 * Make sure the alignment of the structure in the __tracepoints section will
196 * not add unwanted padding between the beginning of the section and the
197 * structure. Force alignment to the same alignment as the section start.
199 * When lockdep is enabled, we make sure to always do the RCU portions of
200 * the tracepoint code, regardless of whether tracing is on. However,
201 * don't check if the condition is false, due to interaction with idle
202 * instrumentation. This lets us find RCU issues triggered with tracepoints
203 * even when this tracepoint is off. This code has no purpose other than
206 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
207 extern struct tracepoint __tracepoint_##name; \
208 static inline void trace_##name(proto) \
210 if (static_key_false(&__tracepoint_##name.key)) \
211 __DO_TRACE(&__tracepoint_##name, \
212 TP_PROTO(data_proto), \
213 TP_ARGS(data_args), \
214 TP_CONDITION(cond), 0); \
215 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
216 rcu_read_lock_sched_notrace(); \
217 rcu_dereference_sched(__tracepoint_##name.funcs);\
218 rcu_read_unlock_sched_notrace(); \
221 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
222 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
224 register_trace_##name(void (*probe)(data_proto), void *data) \
226 return tracepoint_probe_register(&__tracepoint_##name, \
227 (void *)probe, data); \
230 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
233 return tracepoint_probe_register_prio(&__tracepoint_##name, \
234 (void *)probe, data, prio); \
237 unregister_trace_##name(void (*probe)(data_proto), void *data) \
239 return tracepoint_probe_unregister(&__tracepoint_##name,\
240 (void *)probe, data); \
243 check_trace_callback_type_##name(void (*cb)(data_proto)) \
247 trace_##name##_enabled(void) \
249 return static_key_false(&__tracepoint_##name.key); \
252 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
253 #define __TRACEPOINT_ENTRY(name) \
254 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \
256 " .long __tracepoint_" #name " - . \n" \
259 #define __TRACEPOINT_ENTRY(name) \
260 static struct tracepoint * const __tracepoint_ptr_##name __used \
261 __attribute__((section("__tracepoints_ptrs"))) = \
266 * We have no guarantee that gcc and the linker won't up-align the tracepoint
267 * structures, so we create an array of pointers that will be used for iteration
268 * on the tracepoints.
270 #define DEFINE_TRACE_FN(name, reg, unreg) \
271 static const char __tpstrtab_##name[] \
272 __attribute__((section("__tracepoints_strings"))) = #name; \
273 struct tracepoint __tracepoint_##name \
274 __attribute__((section("__tracepoints"), used)) = \
275 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
276 __TRACEPOINT_ENTRY(name);
278 #define DEFINE_TRACE(name) \
279 DEFINE_TRACE_FN(name, NULL, NULL);
281 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
282 EXPORT_SYMBOL_GPL(__tracepoint_##name)
283 #define EXPORT_TRACEPOINT_SYMBOL(name) \
284 EXPORT_SYMBOL(__tracepoint_##name)
286 #else /* !TRACEPOINTS_ENABLED */
287 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
288 static inline void trace_##name(proto) \
290 static inline void trace_##name##_rcuidle(proto) \
293 register_trace_##name(void (*probe)(data_proto), \
299 unregister_trace_##name(void (*probe)(data_proto), \
304 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
308 trace_##name##_enabled(void) \
313 #define DEFINE_TRACE_FN(name, reg, unreg)
314 #define DEFINE_TRACE(name)
315 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
316 #define EXPORT_TRACEPOINT_SYMBOL(name)
318 #endif /* TRACEPOINTS_ENABLED */
320 #ifdef CONFIG_TRACING
322 * tracepoint_string - register constant persistent string to trace system
323 * @str - a constant persistent string that will be referenced in tracepoints
325 * If constant strings are being used in tracepoints, it is faster and
326 * more efficient to just save the pointer to the string and reference
327 * that with a printf "%s" instead of saving the string in the ring buffer
328 * and wasting space and time.
330 * The problem with the above approach is that userspace tools that read
331 * the binary output of the trace buffers do not have access to the string.
332 * Instead they just show the address of the string which is not very
335 * With tracepoint_string(), the string will be registered to the tracing
336 * system and exported to userspace via the debugfs/tracing/printk_formats
337 * file that maps the string address to the string text. This way userspace
338 * tools that read the binary buffers have a way to map the pointers to
339 * the ASCII strings they represent.
341 * The @str used must be a constant string and persistent as it would not
342 * make sense to show a string that no longer exists. But it is still fine
343 * to be used with modules, because when modules are unloaded, if they
344 * had tracepoints, the ring buffers are cleared too. As long as the string
345 * does not change during the life of the module, it is fine to use
346 * tracepoint_string() within a module.
348 #define tracepoint_string(str) \
350 static const char *___tp_str __tracepoint_string = str; \
353 #define __tracepoint_string __attribute__((section("__tracepoint_str")))
356 * tracepoint_string() is used to save the string address for userspace
357 * tracing tools. When tracing isn't configured, there's no need to save
360 # define tracepoint_string(str) str
361 # define __tracepoint_string
365 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
366 * (void). "void" is a special value in a function prototype and can
367 * not be combined with other arguments. Since the DECLARE_TRACE()
368 * macro adds a data element at the beginning of the prototype,
369 * we need a way to differentiate "(void *data, proto)" from
370 * "(void *data, void)". The second prototype is invalid.
372 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
373 * and "void *__data" as the callback prototype.
375 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
376 * "void *__data, proto" as the callback prototype.
378 #define DECLARE_TRACE_NOARGS(name) \
379 __DECLARE_TRACE(name, void, , \
380 cpu_online(raw_smp_processor_id()), \
381 void *__data, __data)
383 #define DECLARE_TRACE(name, proto, args) \
384 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
385 cpu_online(raw_smp_processor_id()), \
386 PARAMS(void *__data, proto), \
387 PARAMS(__data, args))
389 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
390 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
391 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
392 PARAMS(void *__data, proto), \
393 PARAMS(__data, args))
395 #define TRACE_EVENT_FLAGS(event, flag)
397 #define TRACE_EVENT_PERF_PERM(event, expr...)
399 #endif /* DECLARE_TRACE */
403 * For use with the TRACE_EVENT macro:
405 * We define a tracepoint, its arguments, its printk format
406 * and its 'fast binary record' layout.
408 * Firstly, name your tracepoint via TRACE_EVENT(name : the
409 * 'subsystem_event' notation is fine.
411 * Think about this whole construct as the
412 * 'trace_sched_switch() function' from now on.
415 * TRACE_EVENT(sched_switch,
418 * * A function has a regular function arguments
419 * * prototype, declare it via TP_PROTO():
422 * TP_PROTO(struct rq *rq, struct task_struct *prev,
423 * struct task_struct *next),
426 * * Define the call signature of the 'function'.
427 * * (Design sidenote: we use this instead of a
428 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
431 * TP_ARGS(rq, prev, next),
434 * * Fast binary tracing: define the trace record via
435 * * TP_STRUCT__entry(). You can think about it like a
436 * * regular C structure local variable definition.
438 * * This is how the trace record is structured and will
439 * * be saved into the ring buffer. These are the fields
440 * * that will be exposed to user-space in
441 * * /sys/kernel/debug/tracing/events/<*>/format.
443 * * The declared 'local variable' is called '__entry'
445 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
449 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
451 * * char prev_comm[TASK_COMM_LEN];
455 * __array( char, prev_comm, TASK_COMM_LEN )
456 * __field( pid_t, prev_pid )
457 * __field( int, prev_prio )
458 * __array( char, next_comm, TASK_COMM_LEN )
459 * __field( pid_t, next_pid )
460 * __field( int, next_prio )
464 * * Assign the entry into the trace record, by embedding
465 * * a full C statement block into TP_fast_assign(). You
466 * * can refer to the trace record as '__entry' -
467 * * otherwise you can put arbitrary C code in here.
469 * * Note: this C code will execute every time a trace event
470 * * happens, on an active tracepoint.
474 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
475 * __entry->prev_pid = prev->pid;
476 * __entry->prev_prio = prev->prio;
477 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
478 * __entry->next_pid = next->pid;
479 * __entry->next_prio = next->prio;
483 * * Formatted output of a trace record via TP_printk().
484 * * This is how the tracepoint will appear under ftrace
485 * * plugins that make use of this tracepoint.
487 * * (raw-binary tracing wont actually perform this step.)
490 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
491 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
492 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
496 * This macro construct is thus used for the regular printk format
497 * tracing setup, it is used to construct a function pointer based
498 * tracepoint callback (this is used by programmatic plugins and
499 * can also by used by generic instrumentation like SystemTap), and
500 * it is also used to expose a structured trace record in
501 * /sys/kernel/debug/tracing/events/.
503 * A set of (un)registration functions can be passed to the variant
504 * TRACE_EVENT_FN to perform any (un)registration work.
507 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
508 #define DEFINE_EVENT(template, name, proto, args) \
509 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
510 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
511 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
512 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
513 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
514 #define DEFINE_EVENT_CONDITION(template, name, proto, \
516 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
517 PARAMS(args), PARAMS(cond))
519 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
520 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
521 #define TRACE_EVENT_FN(name, proto, args, struct, \
522 assign, print, reg, unreg) \
523 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
524 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
525 assign, print, reg, unreg) \
526 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
527 PARAMS(args), PARAMS(cond))
528 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
529 struct, assign, print) \
530 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
531 PARAMS(args), PARAMS(cond))
533 #define TRACE_EVENT_FLAGS(event, flag)
535 #define TRACE_EVENT_PERF_PERM(event, expr...)
537 #endif /* ifdef TRACE_EVENT (see note above) */