Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf
[firefly-linux-kernel-4.4.55.git] / include / linux / tracepoint.h
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/errno.h>
18 #include <linux/types.h>
19 #include <linux/rcupdate.h>
20 #include <linux/static_key.h>
21
22 struct module;
23 struct tracepoint;
24 struct notifier_block;
25
26 struct tracepoint_func {
27         void *func;
28         void *data;
29         int prio;
30 };
31
32 struct tracepoint {
33         const char *name;               /* Tracepoint name */
34         struct static_key key;
35         void (*regfunc)(void);
36         void (*unregfunc)(void);
37         struct tracepoint_func __rcu *funcs;
38 };
39
40 struct trace_enum_map {
41         const char              *system;
42         const char              *enum_string;
43         unsigned long           enum_value;
44 };
45
46 #define TRACEPOINT_DEFAULT_PRIO 10
47
48 extern int
49 tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
50 extern int
51 tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
52                                int prio);
53 extern int
54 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
55 extern void
56 for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
57                 void *priv);
58
59 #ifdef CONFIG_MODULES
60 struct tp_module {
61         struct list_head list;
62         struct module *mod;
63 };
64
65 bool trace_module_has_bad_taint(struct module *mod);
66 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
67 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
68 #else
69 static inline bool trace_module_has_bad_taint(struct module *mod)
70 {
71         return false;
72 }
73 static inline
74 int register_tracepoint_module_notifier(struct notifier_block *nb)
75 {
76         return 0;
77 }
78 static inline
79 int unregister_tracepoint_module_notifier(struct notifier_block *nb)
80 {
81         return 0;
82 }
83 #endif /* CONFIG_MODULES */
84
85 /*
86  * tracepoint_synchronize_unregister must be called between the last tracepoint
87  * probe unregistration and the end of module exit to make sure there is no
88  * caller executing a probe when it is freed.
89  */
90 static inline void tracepoint_synchronize_unregister(void)
91 {
92         synchronize_sched();
93 }
94
95 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
96 extern void syscall_regfunc(void);
97 extern void syscall_unregfunc(void);
98 #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */
99
100 #define PARAMS(args...) args
101
102 #define TRACE_DEFINE_ENUM(x)
103
104 #endif /* _LINUX_TRACEPOINT_H */
105
106 /*
107  * Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
108  *  file ifdef protection.
109  *  This is due to the way trace events work. If a file includes two
110  *  trace event headers under one "CREATE_TRACE_POINTS" the first include
111  *  will override the TRACE_EVENT and break the second include.
112  */
113
114 #ifndef DECLARE_TRACE
115
116 #define TP_PROTO(args...)       args
117 #define TP_ARGS(args...)        args
118 #define TP_CONDITION(args...)   args
119
120 /*
121  * Individual subsystem my have a separate configuration to
122  * enable their tracepoints. By default, this file will create
123  * the tracepoints if CONFIG_TRACEPOINT is defined. If a subsystem
124  * wants to be able to disable its tracepoints from being created
125  * it can define NOTRACE before including the tracepoint headers.
126  */
127 #if defined(CONFIG_TRACEPOINTS) && !defined(NOTRACE)
128 #define TRACEPOINTS_ENABLED
129 #endif
130
131 #ifdef TRACEPOINTS_ENABLED
132
133 /*
134  * it_func[0] is never NULL because there is at least one element in the array
135  * when the array itself is non NULL.
136  *
137  * Note, the proto and args passed in includes "__data" as the first parameter.
138  * The reason for this is to handle the "void" prototype. If a tracepoint
139  * has a "void" prototype, then it is invalid to declare a function
140  * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
141  * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
142  */
143 #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu)              \
144         do {                                                            \
145                 struct tracepoint_func *it_func_ptr;                    \
146                 void *it_func;                                          \
147                 void *__data;                                           \
148                                                                         \
149                 if (!(cond))                                            \
150                         return;                                         \
151                 prercu;                                                 \
152                 rcu_read_lock_sched_notrace();                          \
153                 it_func_ptr = rcu_dereference_sched((tp)->funcs);       \
154                 if (it_func_ptr) {                                      \
155                         do {                                            \
156                                 it_func = (it_func_ptr)->func;          \
157                                 __data = (it_func_ptr)->data;           \
158                                 ((void(*)(proto))(it_func))(args);      \
159                         } while ((++it_func_ptr)->func);                \
160                 }                                                       \
161                 rcu_read_unlock_sched_notrace();                        \
162                 postrcu;                                                \
163         } while (0)
164
165 #ifndef MODULE
166 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)     \
167         static inline void trace_##name##_rcuidle(proto)                \
168         {                                                               \
169                 if (static_key_false(&__tracepoint_##name.key))         \
170                         __DO_TRACE(&__tracepoint_##name,                \
171                                 TP_PROTO(data_proto),                   \
172                                 TP_ARGS(data_args),                     \
173                                 TP_CONDITION(cond),                     \
174                                 rcu_irq_enter(),                        \
175                                 rcu_irq_exit());                        \
176         }
177 #else
178 #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
179 #endif
180
181 /*
182  * Make sure the alignment of the structure in the __tracepoints section will
183  * not add unwanted padding between the beginning of the section and the
184  * structure. Force alignment to the same alignment as the section start.
185  *
186  * When lockdep is enabled, we make sure to always do the RCU portions of
187  * the tracepoint code, regardless of whether tracing is on. However,
188  * don't check if the condition is false, due to interaction with idle
189  * instrumentation. This lets us find RCU issues triggered with tracepoints
190  * even when this tracepoint is off. This code has no purpose other than
191  * poking RCU a bit.
192  */
193 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
194         extern struct tracepoint __tracepoint_##name;                   \
195         static inline void trace_##name(proto)                          \
196         {                                                               \
197                 if (static_key_false(&__tracepoint_##name.key))         \
198                         __DO_TRACE(&__tracepoint_##name,                \
199                                 TP_PROTO(data_proto),                   \
200                                 TP_ARGS(data_args),                     \
201                                 TP_CONDITION(cond),,);                  \
202                 if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {             \
203                         rcu_read_lock_sched_notrace();                  \
204                         rcu_dereference_sched(__tracepoint_##name.funcs);\
205                         rcu_read_unlock_sched_notrace();                \
206                 }                                                       \
207         }                                                               \
208         __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),          \
209                 PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))    \
210         static inline int                                               \
211         register_trace_##name(void (*probe)(data_proto), void *data)    \
212         {                                                               \
213                 return tracepoint_probe_register(&__tracepoint_##name,  \
214                                                 (void *)probe, data);   \
215         }                                                               \
216         static inline int                                               \
217         register_trace_prio_##name(void (*probe)(data_proto), void *data,\
218                                    int prio)                            \
219         {                                                               \
220                 return tracepoint_probe_register_prio(&__tracepoint_##name, \
221                                               (void *)probe, data, prio); \
222         }                                                               \
223         static inline int                                               \
224         unregister_trace_##name(void (*probe)(data_proto), void *data)  \
225         {                                                               \
226                 return tracepoint_probe_unregister(&__tracepoint_##name,\
227                                                 (void *)probe, data);   \
228         }                                                               \
229         static inline void                                              \
230         check_trace_callback_type_##name(void (*cb)(data_proto))        \
231         {                                                               \
232         }                                                               \
233         static inline bool                                              \
234         trace_##name##_enabled(void)                                    \
235         {                                                               \
236                 return static_key_false(&__tracepoint_##name.key);      \
237         }
238
239 /*
240  * We have no guarantee that gcc and the linker won't up-align the tracepoint
241  * structures, so we create an array of pointers that will be used for iteration
242  * on the tracepoints.
243  */
244 #define DEFINE_TRACE_FN(name, reg, unreg)                                \
245         static const char __tpstrtab_##name[]                            \
246         __attribute__((section("__tracepoints_strings"))) = #name;       \
247         struct tracepoint __tracepoint_##name                            \
248         __attribute__((section("__tracepoints"))) =                      \
249                 { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
250         static struct tracepoint * const __tracepoint_ptr_##name __used  \
251         __attribute__((section("__tracepoints_ptrs"))) =                 \
252                 &__tracepoint_##name;
253
254 #define DEFINE_TRACE(name)                                              \
255         DEFINE_TRACE_FN(name, NULL, NULL);
256
257 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
258         EXPORT_SYMBOL_GPL(__tracepoint_##name)
259 #define EXPORT_TRACEPOINT_SYMBOL(name)                                  \
260         EXPORT_SYMBOL(__tracepoint_##name)
261
262 #else /* !TRACEPOINTS_ENABLED */
263 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
264         static inline void trace_##name(proto)                          \
265         { }                                                             \
266         static inline void trace_##name##_rcuidle(proto)                \
267         { }                                                             \
268         static inline int                                               \
269         register_trace_##name(void (*probe)(data_proto),                \
270                               void *data)                               \
271         {                                                               \
272                 return -ENOSYS;                                         \
273         }                                                               \
274         static inline int                                               \
275         unregister_trace_##name(void (*probe)(data_proto),              \
276                                 void *data)                             \
277         {                                                               \
278                 return -ENOSYS;                                         \
279         }                                                               \
280         static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
281         {                                                               \
282         }                                                               \
283         static inline bool                                              \
284         trace_##name##_enabled(void)                                    \
285         {                                                               \
286                 return false;                                           \
287         }
288
289 #define DEFINE_TRACE_FN(name, reg, unreg)
290 #define DEFINE_TRACE(name)
291 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
292 #define EXPORT_TRACEPOINT_SYMBOL(name)
293
294 #endif /* TRACEPOINTS_ENABLED */
295
296 #ifdef CONFIG_TRACING
297 /**
298  * tracepoint_string - register constant persistent string to trace system
299  * @str - a constant persistent string that will be referenced in tracepoints
300  *
301  * If constant strings are being used in tracepoints, it is faster and
302  * more efficient to just save the pointer to the string and reference
303  * that with a printf "%s" instead of saving the string in the ring buffer
304  * and wasting space and time.
305  *
306  * The problem with the above approach is that userspace tools that read
307  * the binary output of the trace buffers do not have access to the string.
308  * Instead they just show the address of the string which is not very
309  * useful to users.
310  *
311  * With tracepoint_string(), the string will be registered to the tracing
312  * system and exported to userspace via the debugfs/tracing/printk_formats
313  * file that maps the string address to the string text. This way userspace
314  * tools that read the binary buffers have a way to map the pointers to
315  * the ASCII strings they represent.
316  *
317  * The @str used must be a constant string and persistent as it would not
318  * make sense to show a string that no longer exists. But it is still fine
319  * to be used with modules, because when modules are unloaded, if they
320  * had tracepoints, the ring buffers are cleared too. As long as the string
321  * does not change during the life of the module, it is fine to use
322  * tracepoint_string() within a module.
323  */
324 #define tracepoint_string(str)                                          \
325         ({                                                              \
326                 static const char *___tp_str __tracepoint_string = str; \
327                 ___tp_str;                                              \
328         })
329 #define __tracepoint_string     __attribute__((section("__tracepoint_str")))
330 #else
331 /*
332  * tracepoint_string() is used to save the string address for userspace
333  * tracing tools. When tracing isn't configured, there's no need to save
334  * anything.
335  */
336 # define tracepoint_string(str) str
337 # define __tracepoint_string
338 #endif
339
340 /*
341  * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
342  * (void). "void" is a special value in a function prototype and can
343  * not be combined with other arguments. Since the DECLARE_TRACE()
344  * macro adds a data element at the beginning of the prototype,
345  * we need a way to differentiate "(void *data, proto)" from
346  * "(void *data, void)". The second prototype is invalid.
347  *
348  * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
349  * and "void *__data" as the callback prototype.
350  *
351  * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
352  * "void *__data, proto" as the callback prototype.
353  */
354 #define DECLARE_TRACE_NOARGS(name)                                      \
355                 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
356
357 #define DECLARE_TRACE(name, proto, args)                                \
358                 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1,   \
359                                 PARAMS(void *__data, proto),            \
360                                 PARAMS(__data, args))
361
362 #define DECLARE_TRACE_CONDITION(name, proto, args, cond)                \
363         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
364                         PARAMS(void *__data, proto),                    \
365                         PARAMS(__data, args))
366
367 #define TRACE_EVENT_FLAGS(event, flag)
368
369 #define TRACE_EVENT_PERF_PERM(event, expr...)
370
371 #endif /* DECLARE_TRACE */
372
373 #ifndef TRACE_EVENT
374 /*
375  * For use with the TRACE_EVENT macro:
376  *
377  * We define a tracepoint, its arguments, its printk format
378  * and its 'fast binary record' layout.
379  *
380  * Firstly, name your tracepoint via TRACE_EVENT(name : the
381  * 'subsystem_event' notation is fine.
382  *
383  * Think about this whole construct as the
384  * 'trace_sched_switch() function' from now on.
385  *
386  *
387  *  TRACE_EVENT(sched_switch,
388  *
389  *      *
390  *      * A function has a regular function arguments
391  *      * prototype, declare it via TP_PROTO():
392  *      *
393  *
394  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
395  *               struct task_struct *next),
396  *
397  *      *
398  *      * Define the call signature of the 'function'.
399  *      * (Design sidenote: we use this instead of a
400  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
401  *      *
402  *
403  *      TP_ARGS(rq, prev, next),
404  *
405  *      *
406  *      * Fast binary tracing: define the trace record via
407  *      * TP_STRUCT__entry(). You can think about it like a
408  *      * regular C structure local variable definition.
409  *      *
410  *      * This is how the trace record is structured and will
411  *      * be saved into the ring buffer. These are the fields
412  *      * that will be exposed to user-space in
413  *      * /sys/kernel/debug/tracing/events/<*>/format.
414  *      *
415  *      * The declared 'local variable' is called '__entry'
416  *      *
417  *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
418  *      *
419  *      *       pid_t   prev_pid;
420  *      *
421  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
422  *      *
423  *      *       char    prev_comm[TASK_COMM_LEN];
424  *      *
425  *
426  *      TP_STRUCT__entry(
427  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
428  *              __field(        pid_t,  prev_pid                        )
429  *              __field(        int,    prev_prio                       )
430  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
431  *              __field(        pid_t,  next_pid                        )
432  *              __field(        int,    next_prio                       )
433  *      ),
434  *
435  *      *
436  *      * Assign the entry into the trace record, by embedding
437  *      * a full C statement block into TP_fast_assign(). You
438  *      * can refer to the trace record as '__entry' -
439  *      * otherwise you can put arbitrary C code in here.
440  *      *
441  *      * Note: this C code will execute every time a trace event
442  *      * happens, on an active tracepoint.
443  *      *
444  *
445  *      TP_fast_assign(
446  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
447  *              __entry->prev_pid       = prev->pid;
448  *              __entry->prev_prio      = prev->prio;
449  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
450  *              __entry->next_pid       = next->pid;
451  *              __entry->next_prio      = next->prio;
452  *      ),
453  *
454  *      *
455  *      * Formatted output of a trace record via TP_printk().
456  *      * This is how the tracepoint will appear under ftrace
457  *      * plugins that make use of this tracepoint.
458  *      *
459  *      * (raw-binary tracing wont actually perform this step.)
460  *      *
461  *
462  *      TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
463  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
464  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
465  *
466  * );
467  *
468  * This macro construct is thus used for the regular printk format
469  * tracing setup, it is used to construct a function pointer based
470  * tracepoint callback (this is used by programmatic plugins and
471  * can also by used by generic instrumentation like SystemTap), and
472  * it is also used to expose a structured trace record in
473  * /sys/kernel/debug/tracing/events/.
474  *
475  * A set of (un)registration functions can be passed to the variant
476  * TRACE_EVENT_FN to perform any (un)registration work.
477  */
478
479 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
480 #define DEFINE_EVENT(template, name, proto, args)               \
481         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
482 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
483         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
484 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
485         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
486 #define DEFINE_EVENT_CONDITION(template, name, proto,           \
487                                args, cond)                      \
488         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
489                                 PARAMS(args), PARAMS(cond))
490
491 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
492         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
493 #define TRACE_EVENT_FN(name, proto, args, struct,               \
494                 assign, print, reg, unreg)                      \
495         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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) */