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_register_prio_may_exist(struct tracepoint *tp, void *probe, void *data,
48 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
50 tracepoint_probe_register_may_exist(struct tracepoint *tp, void *probe,
53 return tracepoint_probe_register_prio_may_exist(tp, probe, data,
54 TRACEPOINT_DEFAULT_PRIO);
57 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
62 struct list_head list;
66 bool trace_module_has_bad_taint(struct module *mod);
67 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
68 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
70 static inline bool trace_module_has_bad_taint(struct module *mod)
75 int register_tracepoint_module_notifier(struct notifier_block *nb)
80 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
84 #endif /* CONFIG_MODULES */
87 * tracepoint_synchronize_unregister must be called between the last tracepoint
88 * probe unregistration and the end of module exit to make sure there is no
89 * caller executing a probe when it is freed.
91 #ifdef CONFIG_TRACEPOINTS
92 static inline void tracepoint_synchronize_unregister(void)
94 synchronize_srcu(&tracepoint_srcu);
98 static inline void tracepoint_synchronize_unregister(void)
102 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
103 extern int syscall_regfunc(void);
104 extern void syscall_unregfunc(void);
105 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
107 #define PARAMS(args...) args
109 #define TRACE_DEFINE_ENUM(x)
110 #define TRACE_DEFINE_SIZEOF(x)
112 #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
113 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
115 return offset_to_ptr(p);
118 #define __TRACEPOINT_ENTRY(name) \
119 asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \
121 " .long __tracepoint_" #name " - . \n" \
124 static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
129 #define __TRACEPOINT_ENTRY(name) \
130 static tracepoint_ptr_t __tracepoint_ptr_##name __used \
131 __attribute__((section("__tracepoints_ptrs"))) = \
135 #endif /* _LINUX_TRACEPOINT_H */
138 * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
139 * file ifdef protection.
140 * This is due to the way trace events work. If a file includes two
141 * trace event headers under one "CREATE_TRACE_POINTS" the first include
142 * will override the TRACE_EVENT and break the second include.
145 #ifndef DECLARE_TRACE
147 #define TP_PROTO(args...) args
148 #define TP_ARGS(args...) args
149 #define TP_CONDITION(args...) args
152 * Individual subsystem my have a separate configuration to
153 * enable their tracepoints. By default, this file will create
154 * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
155 * wants to be able to disable its tracepoints from being created
156 * it can define NOTRACE before including the tracepoint headers.
158 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
159 #define TRACEPOINTS_ENABLED
162 #ifdef TRACEPOINTS_ENABLED
165 * it_func[0] is never NULL because there is at least one element in the array
166 * when the array itself is non NULL.
168 * Note, the proto and args passed in includes "__data" as the first parameter.
169 * The reason for this is to handle the "void" prototype. If a tracepoint
170 * has a "void" prototype, then it is invalid to declare a function
171 * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
172 * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
174 #define __DO_TRACE(tp, proto, args, cond, rcuidle) \
176 struct tracepoint_func *it_func_ptr; \
179 int __maybe_unused __idx = 0; \
184 /* srcu can't be used from NMI */ \
185 WARN_ON_ONCE(rcuidle && in_nmi()); \
187 /* keep srcu and sched-rcu usage consistent */ \
188 preempt_disable_notrace(); \
191 * For rcuidle callers, use srcu since sched-rcu \
192 * doesn't work from the idle path. \
195 __idx = srcu_read_lock_notrace(&tracepoint_srcu);\
196 rcu_irq_enter_irqson(); \
199 it_func_ptr = rcu_dereference_raw((tp)->funcs); \
203 it_func = (it_func_ptr)->func; \
204 __data = (it_func_ptr)->data; \
205 ((void(*)(proto))(it_func))(args); \
206 } while ((++it_func_ptr)->func); \
210 rcu_irq_exit_irqson(); \
211 srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
214 preempt_enable_notrace(); \
218 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
219 static inline void trace_##name##_rcuidle(proto) \
221 if (static_key_false(&__tracepoint_##name.key)) \
222 __DO_TRACE(&__tracepoint_##name, \
223 TP_PROTO(data_proto), \
224 TP_ARGS(data_args), \
225 TP_CONDITION(cond), 1); \
228 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
232 * Make sure the alignment of the structure in the __tracepoints section will
233 * not add unwanted padding between the beginning of the section and the
234 * structure. Force alignment to the same alignment as the section start.
236 * When lockdep is enabled, we make sure to always do the RCU portions of
237 * the tracepoint code, regardless of whether tracing is on. However,
238 * don't check if the condition is false, due to interaction with idle
239 * instrumentation. This lets us find RCU issues triggered with tracepoints
240 * even when this tracepoint is off. This code has no purpose other than
243 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
244 extern struct tracepoint __tracepoint_##name; \
245 static inline void trace_##name(proto) \
247 if (static_key_false(&__tracepoint_##name.key)) \
248 __DO_TRACE(&__tracepoint_##name, \
249 TP_PROTO(data_proto), \
250 TP_ARGS(data_args), \
251 TP_CONDITION(cond), 0); \
252 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
253 rcu_read_lock_sched_notrace(); \
254 rcu_dereference_sched(__tracepoint_##name.funcs);\
255 rcu_read_unlock_sched_notrace(); \
258 __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
259 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
261 register_trace_##name(void (*probe)(data_proto), void *data) \
263 return tracepoint_probe_register(&__tracepoint_##name, \
264 (void *)probe, data); \
267 register_trace_prio_##name(void (*probe)(data_proto), void *data,\
270 return tracepoint_probe_register_prio(&__tracepoint_##name, \
271 (void *)probe, data, prio); \
274 unregister_trace_##name(void (*probe)(data_proto), void *data) \
276 return tracepoint_probe_unregister(&__tracepoint_##name,\
277 (void *)probe, data); \
280 check_trace_callback_type_##name(void (*cb)(data_proto)) \
284 trace_##name##_enabled(void) \
286 return static_key_false(&__tracepoint_##name.key); \
290 * We have no guarantee that gcc and the linker won't up-align the tracepoint
291 * structures, so we create an array of pointers that will be used for iteration
292 * on the tracepoints.
294 #define DEFINE_TRACE_FN(name, reg, unreg) \
295 static const char __tpstrtab_##name[] \
296 __attribute__((section("__tracepoints_strings"))) = #name; \
297 struct tracepoint __tracepoint_##name \
298 __attribute__((section("__tracepoints"), used)) = \
299 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
300 __TRACEPOINT_ENTRY(name);
302 #define DEFINE_TRACE(name) \
303 DEFINE_TRACE_FN(name, NULL, NULL);
305 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
306 EXPORT_SYMBOL_GPL(__tracepoint_##name)
307 #define EXPORT_TRACEPOINT_SYMBOL(name) \
308 EXPORT_SYMBOL(__tracepoint_##name)
310 #else /* !TRACEPOINTS_ENABLED */
311 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
312 static inline void trace_##name(proto) \
314 static inline void trace_##name##_rcuidle(proto) \
317 register_trace_##name(void (*probe)(data_proto), \
323 unregister_trace_##name(void (*probe)(data_proto), \
328 static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
332 trace_##name##_enabled(void) \
337 #define DEFINE_TRACE_FN(name, reg, unreg)
338 #define DEFINE_TRACE(name)
339 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
340 #define EXPORT_TRACEPOINT_SYMBOL(name)
342 #endif /* TRACEPOINTS_ENABLED */
344 #ifdef CONFIG_TRACING
346 * tracepoint_string - register constant persistent string to trace system
347 * @str - a constant persistent string that will be referenced in tracepoints
349 * If constant strings are being used in tracepoints, it is faster and
350 * more efficient to just save the pointer to the string and reference
351 * that with a printf "%s" instead of saving the string in the ring buffer
352 * and wasting space and time.
354 * The problem with the above approach is that userspace tools that read
355 * the binary output of the trace buffers do not have access to the string.
356 * Instead they just show the address of the string which is not very
359 * With tracepoint_string(), the string will be registered to the tracing
360 * system and exported to userspace via the debugfs/tracing/printk_formats
361 * file that maps the string address to the string text. This way userspace
362 * tools that read the binary buffers have a way to map the pointers to
363 * the ASCII strings they represent.
365 * The @str used must be a constant string and persistent as it would not
366 * make sense to show a string that no longer exists. But it is still fine
367 * to be used with modules, because when modules are unloaded, if they
368 * had tracepoints, the ring buffers are cleared too. As long as the string
369 * does not change during the life of the module, it is fine to use
370 * tracepoint_string() within a module.
372 #define tracepoint_string(str) \
374 static const char *___tp_str __tracepoint_string = str; \
377 #define __tracepoint_string __attribute__((section("__tracepoint_str"), used))
380 * tracepoint_string() is used to save the string address for userspace
381 * tracing tools. When tracing isn't configured, there's no need to save
384 # define tracepoint_string(str) str
385 # define __tracepoint_string
389 * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
390 * (void). "void" is a special value in a function prototype and can
391 * not be combined with other arguments. Since the DECLARE_TRACE()
392 * macro adds a data element at the beginning of the prototype,
393 * we need a way to differentiate "(void *data, proto)" from
394 * "(void *data, void)". The second prototype is invalid.
396 * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
397 * and "void *__data" as the callback prototype.
399 * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
400 * "void *__data, proto" as the callback prototype.
402 #define DECLARE_TRACE_NOARGS(name) \
403 __DECLARE_TRACE(name, void, , \
404 cpu_online(raw_smp_processor_id()), \
405 void *__data, __data)
407 #define DECLARE_TRACE(name, proto, args) \
408 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
409 cpu_online(raw_smp_processor_id()), \
410 PARAMS(void *__data, proto), \
411 PARAMS(__data, args))
413 #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
414 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), \
415 cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
416 PARAMS(void *__data, proto), \
417 PARAMS(__data, args))
419 #define TRACE_EVENT_FLAGS(event, flag)
421 #define TRACE_EVENT_PERF_PERM(event, expr...)
423 #endif /* DECLARE_TRACE */
427 * For use with the TRACE_EVENT macro:
429 * We define a tracepoint, its arguments, its printk format
430 * and its 'fast binary record' layout.
432 * Firstly, name your tracepoint via TRACE_EVENT(name : the
433 * 'subsystem_event' notation is fine.
435 * Think about this whole construct as the
436 * 'trace_sched_switch() function' from now on.
439 * TRACE_EVENT(sched_switch,
442 * * A function has a regular function arguments
443 * * prototype, declare it via TP_PROTO():
446 * TP_PROTO(struct rq *rq, struct task_struct *prev,
447 * struct task_struct *next),
450 * * Define the call signature of the 'function'.
451 * * (Design sidenote: we use this instead of a
452 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
455 * TP_ARGS(rq, prev, next),
458 * * Fast binary tracing: define the trace record via
459 * * TP_STRUCT__entry(). You can think about it like a
460 * * regular C structure local variable definition.
462 * * This is how the trace record is structured and will
463 * * be saved into the ring buffer. These are the fields
464 * * that will be exposed to user-space in
465 * * /sys/kernel/debug/tracing/events/<*>/format.
467 * * The declared 'local variable' is called '__entry'
469 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
473 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
475 * * char prev_comm[TASK_COMM_LEN];
479 * __array( char, prev_comm, TASK_COMM_LEN )
480 * __field( pid_t, prev_pid )
481 * __field( int, prev_prio )
482 * __array( char, next_comm, TASK_COMM_LEN )
483 * __field( pid_t, next_pid )
484 * __field( int, next_prio )
488 * * Assign the entry into the trace record, by embedding
489 * * a full C statement block into TP_fast_assign(). You
490 * * can refer to the trace record as '__entry' -
491 * * otherwise you can put arbitrary C code in here.
493 * * Note: this C code will execute every time a trace event
494 * * happens, on an active tracepoint.
498 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
499 * __entry->prev_pid = prev->pid;
500 * __entry->prev_prio = prev->prio;
501 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
502 * __entry->next_pid = next->pid;
503 * __entry->next_prio = next->prio;
507 * * Formatted output of a trace record via TP_printk().
508 * * This is how the tracepoint will appear under ftrace
509 * * plugins that make use of this tracepoint.
511 * * (raw-binary tracing wont actually perform this step.)
514 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
515 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
516 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
520 * This macro construct is thus used for the regular printk format
521 * tracing setup, it is used to construct a function pointer based
522 * tracepoint callback (this is used by programmatic plugins and
523 * can also by used by generic instrumentation like SystemTap), and
524 * it is also used to expose a structured trace record in
525 * /sys/kernel/debug/tracing/events/.
527 * A set of (un)registration functions can be passed to the variant
528 * TRACE_EVENT_FN to perform any (un)registration work.
531 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
532 #define DEFINE_EVENT(template, name, proto, args) \
533 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
534 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
535 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
536 #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
537 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
538 #define DEFINE_EVENT_CONDITION(template, name, proto, \
540 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
541 PARAMS(args), PARAMS(cond))
543 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
544 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
545 #define TRACE_EVENT_FN(name, proto, args, struct, \
546 assign, print, reg, unreg) \
547 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
548 #define TRACE_EVENT_FN_COND(name, proto, args, cond, struct, \
549 assign, print, reg, unreg) \
550 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
551 PARAMS(args), PARAMS(cond))
552 #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
553 struct, assign, print) \
554 DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
555 PARAMS(args), PARAMS(cond))
557 #define TRACE_EVENT_FLAGS(event, flag)
559 #define TRACE_EVENT_PERF_PERM(event, expr...)
561 #endif /* ifdef TRACE_EVENT (see note above) */