Merge branch 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6
[linux-2.6.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  * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
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/jump_label.h>
21
22 struct module;
23 struct tracepoint;
24
25 struct tracepoint_func {
26         void *func;
27         void *data;
28 };
29
30 struct tracepoint {
31         const char *name;               /* Tracepoint name */
32         int state;                      /* State. */
33         void (*regfunc)(void);
34         void (*unregfunc)(void);
35         struct tracepoint_func __rcu *funcs;
36 };
37
38 /*
39  * Connect a probe to a tracepoint.
40  * Internal API, should not be used directly.
41  */
42 extern int tracepoint_probe_register(const char *name, void *probe, void *data);
43
44 /*
45  * Disconnect a probe from a tracepoint.
46  * Internal API, should not be used directly.
47  */
48 extern int
49 tracepoint_probe_unregister(const char *name, void *probe, void *data);
50
51 extern int tracepoint_probe_register_noupdate(const char *name, void *probe,
52                                               void *data);
53 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
54                                                 void *data);
55 extern void tracepoint_probe_update_all(void);
56
57 struct tracepoint_iter {
58         struct module *module;
59         struct tracepoint * const *tracepoint;
60 };
61
62 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
63 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
64 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
65 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
66 extern int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
67         struct tracepoint * const *begin, struct tracepoint * const *end);
68
69 /*
70  * tracepoint_synchronize_unregister must be called between the last tracepoint
71  * probe unregistration and the end of module exit to make sure there is no
72  * caller executing a probe when it is freed.
73  */
74 static inline void tracepoint_synchronize_unregister(void)
75 {
76         synchronize_sched();
77 }
78
79 #define PARAMS(args...) args
80
81 #ifdef CONFIG_TRACEPOINTS
82 extern
83 void tracepoint_update_probe_range(struct tracepoint * const *begin,
84         struct tracepoint * const *end);
85 #else
86 static inline
87 void tracepoint_update_probe_range(struct tracepoint * const *begin,
88         struct tracepoint * const *end)
89 { }
90 #endif /* CONFIG_TRACEPOINTS */
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 #ifdef CONFIG_TRACEPOINTS
109
110 /*
111  * it_func[0] is never NULL because there is at least one element in the array
112  * when the array itself is non NULL.
113  *
114  * Note, the proto and args passed in includes "__data" as the first parameter.
115  * The reason for this is to handle the "void" prototype. If a tracepoint
116  * has a "void" prototype, then it is invalid to declare a function
117  * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
118  * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
119  */
120 #define __DO_TRACE(tp, proto, args, cond)                               \
121         do {                                                            \
122                 struct tracepoint_func *it_func_ptr;                    \
123                 void *it_func;                                          \
124                 void *__data;                                           \
125                                                                         \
126                 if (!(cond))                                            \
127                         return;                                         \
128                 rcu_read_lock_sched_notrace();                          \
129                 it_func_ptr = rcu_dereference_sched((tp)->funcs);       \
130                 if (it_func_ptr) {                                      \
131                         do {                                            \
132                                 it_func = (it_func_ptr)->func;          \
133                                 __data = (it_func_ptr)->data;           \
134                                 ((void(*)(proto))(it_func))(args);      \
135                         } while ((++it_func_ptr)->func);                \
136                 }                                                       \
137                 rcu_read_unlock_sched_notrace();                        \
138         } while (0)
139
140 /*
141  * Make sure the alignment of the structure in the __tracepoints section will
142  * not add unwanted padding between the beginning of the section and the
143  * structure. Force alignment to the same alignment as the section start.
144  */
145 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
146         extern struct tracepoint __tracepoint_##name;                   \
147         static inline void trace_##name(proto)                          \
148         {                                                               \
149                 JUMP_LABEL(&__tracepoint_##name.state, do_trace);       \
150                 return;                                                 \
151 do_trace:                                                               \
152                         __DO_TRACE(&__tracepoint_##name,                \
153                                 TP_PROTO(data_proto),                   \
154                                 TP_ARGS(data_args),                     \
155                                 TP_CONDITION(cond));                    \
156         }                                                               \
157         static inline int                                               \
158         register_trace_##name(void (*probe)(data_proto), void *data)    \
159         {                                                               \
160                 return tracepoint_probe_register(#name, (void *)probe,  \
161                                                  data);                 \
162         }                                                               \
163         static inline int                                               \
164         unregister_trace_##name(void (*probe)(data_proto), void *data)  \
165         {                                                               \
166                 return tracepoint_probe_unregister(#name, (void *)probe, \
167                                                    data);               \
168         }                                                               \
169         static inline void                                              \
170         check_trace_callback_type_##name(void (*cb)(data_proto))        \
171         {                                                               \
172         }
173
174 /*
175  * We have no guarantee that gcc and the linker won't up-align the tracepoint
176  * structures, so we create an array of pointers that will be used for iteration
177  * on the tracepoints.
178  */
179 #define DEFINE_TRACE_FN(name, reg, unreg)                               \
180         static const char __tpstrtab_##name[]                           \
181         __attribute__((section("__tracepoints_strings"))) = #name;      \
182         struct tracepoint __tracepoint_##name                           \
183         __attribute__((section("__tracepoints"))) =                     \
184                 { __tpstrtab_##name, 0, reg, unreg, NULL };             \
185         static struct tracepoint * const __tracepoint_ptr_##name __used \
186         __attribute__((section("__tracepoints_ptrs"))) =                \
187                 &__tracepoint_##name;
188
189 #define DEFINE_TRACE(name)                                              \
190         DEFINE_TRACE_FN(name, NULL, NULL);
191
192 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
193         EXPORT_SYMBOL_GPL(__tracepoint_##name)
194 #define EXPORT_TRACEPOINT_SYMBOL(name)                                  \
195         EXPORT_SYMBOL(__tracepoint_##name)
196
197 #else /* !CONFIG_TRACEPOINTS */
198 #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
199         static inline void trace_##name(proto)                          \
200         { }                                                             \
201         static inline int                                               \
202         register_trace_##name(void (*probe)(data_proto),                \
203                               void *data)                               \
204         {                                                               \
205                 return -ENOSYS;                                         \
206         }                                                               \
207         static inline int                                               \
208         unregister_trace_##name(void (*probe)(data_proto),              \
209                                 void *data)                             \
210         {                                                               \
211                 return -ENOSYS;                                         \
212         }                                                               \
213         static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
214         {                                                               \
215         }
216
217 #define DEFINE_TRACE_FN(name, reg, unreg)
218 #define DEFINE_TRACE(name)
219 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
220 #define EXPORT_TRACEPOINT_SYMBOL(name)
221
222 #endif /* CONFIG_TRACEPOINTS */
223
224 /*
225  * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
226  * (void). "void" is a special value in a function prototype and can
227  * not be combined with other arguments. Since the DECLARE_TRACE()
228  * macro adds a data element at the beginning of the prototype,
229  * we need a way to differentiate "(void *data, proto)" from
230  * "(void *data, void)". The second prototype is invalid.
231  *
232  * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
233  * and "void *__data" as the callback prototype.
234  *
235  * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
236  * "void *__data, proto" as the callback prototype.
237  */
238 #define DECLARE_TRACE_NOARGS(name)                                      \
239                 __DECLARE_TRACE(name, void, , 1, void *__data, __data)
240
241 #define DECLARE_TRACE(name, proto, args)                                \
242                 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1,   \
243                                 PARAMS(void *__data, proto),            \
244                                 PARAMS(__data, args))
245
246 #define DECLARE_TRACE_CONDITION(name, proto, args, cond)                \
247         __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
248                         PARAMS(void *__data, proto),                    \
249                         PARAMS(__data, args))
250
251 #define TRACE_EVENT_FLAGS(event, flag)
252
253 #endif /* DECLARE_TRACE */
254
255 #ifndef TRACE_EVENT
256 /*
257  * For use with the TRACE_EVENT macro:
258  *
259  * We define a tracepoint, its arguments, its printk format
260  * and its 'fast binay record' layout.
261  *
262  * Firstly, name your tracepoint via TRACE_EVENT(name : the
263  * 'subsystem_event' notation is fine.
264  *
265  * Think about this whole construct as the
266  * 'trace_sched_switch() function' from now on.
267  *
268  *
269  *  TRACE_EVENT(sched_switch,
270  *
271  *      *
272  *      * A function has a regular function arguments
273  *      * prototype, declare it via TP_PROTO():
274  *      *
275  *
276  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
277  *               struct task_struct *next),
278  *
279  *      *
280  *      * Define the call signature of the 'function'.
281  *      * (Design sidenote: we use this instead of a
282  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
283  *      *
284  *
285  *      TP_ARGS(rq, prev, next),
286  *
287  *      *
288  *      * Fast binary tracing: define the trace record via
289  *      * TP_STRUCT__entry(). You can think about it like a
290  *      * regular C structure local variable definition.
291  *      *
292  *      * This is how the trace record is structured and will
293  *      * be saved into the ring buffer. These are the fields
294  *      * that will be exposed to user-space in
295  *      * /sys/kernel/debug/tracing/events/<*>/format.
296  *      *
297  *      * The declared 'local variable' is called '__entry'
298  *      *
299  *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
300  *      *
301  *      *       pid_t   prev_pid;
302  *      *
303  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
304  *      *
305  *      *       char    prev_comm[TASK_COMM_LEN];
306  *      *
307  *
308  *      TP_STRUCT__entry(
309  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
310  *              __field(        pid_t,  prev_pid                        )
311  *              __field(        int,    prev_prio                       )
312  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
313  *              __field(        pid_t,  next_pid                        )
314  *              __field(        int,    next_prio                       )
315  *      ),
316  *
317  *      *
318  *      * Assign the entry into the trace record, by embedding
319  *      * a full C statement block into TP_fast_assign(). You
320  *      * can refer to the trace record as '__entry' -
321  *      * otherwise you can put arbitrary C code in here.
322  *      *
323  *      * Note: this C code will execute every time a trace event
324  *      * happens, on an active tracepoint.
325  *      *
326  *
327  *      TP_fast_assign(
328  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
329  *              __entry->prev_pid       = prev->pid;
330  *              __entry->prev_prio      = prev->prio;
331  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
332  *              __entry->next_pid       = next->pid;
333  *              __entry->next_prio      = next->prio;
334  *      ),
335  *
336  *      *
337  *      * Formatted output of a trace record via TP_printk().
338  *      * This is how the tracepoint will appear under ftrace
339  *      * plugins that make use of this tracepoint.
340  *      *
341  *      * (raw-binary tracing wont actually perform this step.)
342  *      *
343  *
344  *      TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
345  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
346  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
347  *
348  * );
349  *
350  * This macro construct is thus used for the regular printk format
351  * tracing setup, it is used to construct a function pointer based
352  * tracepoint callback (this is used by programmatic plugins and
353  * can also by used by generic instrumentation like SystemTap), and
354  * it is also used to expose a structured trace record in
355  * /sys/kernel/debug/tracing/events/.
356  *
357  * A set of (un)registration functions can be passed to the variant
358  * TRACE_EVENT_FN to perform any (un)registration work.
359  */
360
361 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
362 #define DEFINE_EVENT(template, name, proto, args)               \
363         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
364 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
365         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
366 #define DEFINE_EVENT_CONDITION(template, name, proto,           \
367                                args, cond)                      \
368         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
369                                 PARAMS(args), PARAMS(cond))
370
371 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
372         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
373 #define TRACE_EVENT_FN(name, proto, args, struct,               \
374                 assign, print, reg, unreg)                      \
375         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
376 #define TRACE_EVENT_CONDITION(name, proto, args, cond,          \
377                               struct, assign, print)            \
378         DECLARE_TRACE_CONDITION(name, PARAMS(proto),            \
379                                 PARAMS(args), PARAMS(cond))
380
381 #define TRACE_EVENT_FLAGS(event, flag)
382
383 #endif /* ifdef TRACE_EVENT (see note above) */