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Mathieu Desnoyers97e1c182008-07-18 12:16:16 -04001#ifndef _LINUX_TRACEPOINT_H
2#define _LINUX_TRACEPOINT_H
3
4/*
5 * Kernel Tracepoint API.
6 *
7 * See Documentation/tracepoint.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/types.h>
18#include <linux/rcupdate.h>
19
20struct module;
21struct tracepoint;
22
23struct tracepoint {
24 const char *name; /* Tracepoint name */
25 int state; /* State. */
26 void **funcs;
Mathieu Desnoyers7e066fb2008-11-14 17:47:47 -050027} __attribute__((aligned(32))); /*
28 * Aligned on 32 bytes because it is
29 * globally visible and gcc happily
30 * align these on the structure size.
31 * Keep in sync with vmlinux.lds.h.
32 */
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040033
Steven Rostedt2939b042009-03-09 15:47:18 -040034#define TP_PROTO(args...) args
35#define TP_ARGS(args...) args
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040036
37#ifdef CONFIG_TRACEPOINTS
38
39/*
40 * it_func[0] is never NULL because there is at least one element in the array
41 * when the array itself is non NULL.
42 */
43#define __DO_TRACE(tp, proto, args) \
44 do { \
45 void **it_func; \
46 \
Mathieu Desnoyersda7b3ea2008-11-14 17:47:43 -050047 rcu_read_lock_sched_notrace(); \
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040048 it_func = rcu_dereference((tp)->funcs); \
49 if (it_func) { \
50 do { \
51 ((void(*)(proto))(*it_func))(args); \
52 } while (*(++it_func)); \
53 } \
Mathieu Desnoyersda7b3ea2008-11-14 17:47:43 -050054 rcu_read_unlock_sched_notrace(); \
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040055 } while (0)
56
57/*
58 * Make sure the alignment of the structure in the __tracepoints section will
59 * not add unwanted padding between the beginning of the section and the
60 * structure. Force alignment to the same alignment as the section start.
61 */
Mathieu Desnoyers7e066fb2008-11-14 17:47:47 -050062#define DECLARE_TRACE(name, proto, args) \
63 extern struct tracepoint __tracepoint_##name; \
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040064 static inline void trace_##name(proto) \
65 { \
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040066 if (unlikely(__tracepoint_##name.state)) \
67 __DO_TRACE(&__tracepoint_##name, \
Steven Rostedt2939b042009-03-09 15:47:18 -040068 TP_PROTO(proto), TP_ARGS(args)); \
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040069 } \
70 static inline int register_trace_##name(void (*probe)(proto)) \
71 { \
Mathieu Desnoyers5f382672008-11-14 17:47:45 -050072 return tracepoint_probe_register(#name, (void *)probe); \
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040073 } \
Mathieu Desnoyersc4209702008-11-14 17:47:44 -050074 static inline int unregister_trace_##name(void (*probe)(proto)) \
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040075 { \
Mathieu Desnoyers5f382672008-11-14 17:47:45 -050076 return tracepoint_probe_unregister(#name, (void *)probe);\
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040077 }
78
Mathieu Desnoyers7e066fb2008-11-14 17:47:47 -050079#define DEFINE_TRACE(name) \
80 static const char __tpstrtab_##name[] \
81 __attribute__((section("__tracepoints_strings"))) = #name; \
82 struct tracepoint __tracepoint_##name \
83 __attribute__((section("__tracepoints"), aligned(32))) = \
84 { __tpstrtab_##name, 0, NULL }
85
86#define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
87 EXPORT_SYMBOL_GPL(__tracepoint_##name)
88#define EXPORT_TRACEPOINT_SYMBOL(name) \
89 EXPORT_SYMBOL(__tracepoint_##name)
90
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040091extern void tracepoint_update_probe_range(struct tracepoint *begin,
92 struct tracepoint *end);
93
94#else /* !CONFIG_TRACEPOINTS */
Mathieu Desnoyers7e066fb2008-11-14 17:47:47 -050095#define DECLARE_TRACE(name, proto, args) \
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -040096 static inline void _do_trace_##name(struct tracepoint *tp, proto) \
97 { } \
98 static inline void trace_##name(proto) \
99 { } \
100 static inline int register_trace_##name(void (*probe)(proto)) \
101 { \
102 return -ENOSYS; \
103 } \
Mathieu Desnoyersc4209702008-11-14 17:47:44 -0500104 static inline int unregister_trace_##name(void (*probe)(proto)) \
105 { \
106 return -ENOSYS; \
107 }
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400108
Mathieu Desnoyers7e066fb2008-11-14 17:47:47 -0500109#define DEFINE_TRACE(name)
110#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
111#define EXPORT_TRACEPOINT_SYMBOL(name)
112
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400113static inline void tracepoint_update_probe_range(struct tracepoint *begin,
114 struct tracepoint *end)
115{ }
116#endif /* CONFIG_TRACEPOINTS */
117
118/*
119 * Connect a probe to a tracepoint.
120 * Internal API, should not be used directly.
121 */
122extern int tracepoint_probe_register(const char *name, void *probe);
123
124/*
125 * Disconnect a probe from a tracepoint.
126 * Internal API, should not be used directly.
127 */
128extern int tracepoint_probe_unregister(const char *name, void *probe);
129
Lai Jiangshan127cafb2008-10-28 10:51:53 +0800130extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
131extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
132extern void tracepoint_probe_update_all(void);
133
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400134struct tracepoint_iter {
135 struct module *module;
136 struct tracepoint *tracepoint;
137};
138
139extern void tracepoint_iter_start(struct tracepoint_iter *iter);
140extern void tracepoint_iter_next(struct tracepoint_iter *iter);
141extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
142extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
143extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
144 struct tracepoint *begin, struct tracepoint *end);
145
Mathieu Desnoyersf2461fc2008-10-06 10:33:00 -0400146/*
147 * tracepoint_synchronize_unregister must be called between the last tracepoint
148 * probe unregistration and the end of module exit to make sure there is no
149 * caller executing a probe when it is freed.
150 */
Mathieu Desnoyers231375c2008-10-03 15:01:33 -0400151static inline void tracepoint_synchronize_unregister(void)
152{
153 synchronize_sched();
154}
Mathieu Desnoyersf2461fc2008-10-06 10:33:00 -0400155
Steven Rostedt3cdfdf92009-02-25 15:54:30 -0500156#define PARAMS(args...) args
Steven Rostedteef62a62009-02-25 15:49:52 -0500157#define TRACE_FORMAT(name, proto, args, fmt) \
Steven Rostedt3cdfdf92009-02-25 15:54:30 -0500158 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
Steven Rostedt7c377302009-02-24 12:07:53 -0500159
Steven Rostedt823f9122009-03-10 12:58:51 -0400160
161/*
162 * For use with the TRACE_EVENT macro:
163 *
164 * We define a tracepoint, its arguments, its printk format
165 * and its 'fast binay record' layout.
166 *
167 * Firstly, name your tracepoint via TRACE_EVENT(name : the
168 * 'subsystem_event' notation is fine.
169 *
170 * Think about this whole construct as the
171 * 'trace_sched_switch() function' from now on.
172 *
173 *
174 * TRACE_EVENT(sched_switch,
175 *
176 * *
177 * * A function has a regular function arguments
178 * * prototype, declare it via TP_PROTO():
179 * *
180 *
181 * TP_PROTO(struct rq *rq, struct task_struct *prev,
182 * struct task_struct *next),
183 *
184 * *
185 * * Define the call signature of the 'function'.
186 * * (Design sidenote: we use this instead of a
187 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
188 * *
189 *
190 * TP_ARGS(rq, prev, next),
191 *
192 * *
193 * * Fast binary tracing: define the trace record via
194 * * TP_STRUCT__entry(). You can think about it like a
195 * * regular C structure local variable definition.
196 * *
197 * * This is how the trace record is structured and will
198 * * be saved into the ring buffer. These are the fields
199 * * that will be exposed to user-space in
200 * * /debug/tracing/events/<*>/format.
201 * *
202 * * The declared 'local variable' is called '__entry'
203 * *
204 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
205 * *
206 * * pid_t prev_pid;
207 * *
208 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
209 * *
210 * * char prev_comm[TASK_COMM_LEN];
211 * *
212 *
213 * TP_STRUCT__entry(
214 * __array( char, prev_comm, TASK_COMM_LEN )
215 * __field( pid_t, prev_pid )
216 * __field( int, prev_prio )
217 * __array( char, next_comm, TASK_COMM_LEN )
218 * __field( pid_t, next_pid )
219 * __field( int, next_prio )
220 * ),
221 *
222 * *
223 * * Assign the entry into the trace record, by embedding
224 * * a full C statement block into TP_fast_assign(). You
225 * * can refer to the trace record as '__entry' -
226 * * otherwise you can put arbitrary C code in here.
227 * *
228 * * Note: this C code will execute every time a trace event
229 * * happens, on an active tracepoint.
230 * *
231 *
232 * TP_fast_assign(
233 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
234 * __entry->prev_pid = prev->pid;
235 * __entry->prev_prio = prev->prio;
236 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
237 * __entry->next_pid = next->pid;
238 * __entry->next_prio = next->prio;
239 * )
240 *
241 * *
242 * * Formatted output of a trace record via TP_printk().
243 * * This is how the tracepoint will appear under ftrace
244 * * plugins that make use of this tracepoint.
245 * *
246 * * (raw-binary tracing wont actually perform this step.)
247 * *
248 *
249 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
250 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
251 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
252 *
253 * );
254 *
255 * This macro construct is thus used for the regular printk format
256 * tracing setup, it is used to construct a function pointer based
257 * tracepoint callback (this is used by programmatic plugins and
258 * can also by used by generic instrumentation like SystemTap), and
259 * it is also used to expose a structured trace record in
260 * /debug/tracing/events/.
261 */
262
Steven Rostedt30a8fec2009-03-10 12:41:38 -0400263#define TRACE_EVENT(name, proto, args, struct, assign, print) \
Steven Rostedtda4d0302009-03-09 17:14:30 -0400264 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
265
Mathieu Desnoyers97e1c182008-07-18 12:16:16 -0400266#endif