1 #ifndef _UST_TRACEPOINT_H
2 #define _UST_TRACEPOINT_H
5 * Copyright (C) 2008-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * Copyright (C) 2009 Pierre-Marc Fournier
7 * Copyright (C) 2009 Steven Rostedt <rostedt@goodmis.org>
9 * This library is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation;
12 * version 2.1 of the License.
14 * This library is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this library; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 * Heavily inspired from the Linux Kernel Markers.
25 * Ported to userspace by Pierre-Marc Fournier.
29 #include <urcu/list.h>
31 struct tracepoint_probe
{
37 const char *name
; /* Tracepoint name */
38 char state
; /* State. */
39 struct tracepoint_probe
*probes
;
43 * Tracepoints should be added to the instrumented code using the
44 * "tracepoint()" macro.
46 #define tracepoint(name, args...) __trace_##name(args)
49 * it_func[0] is never NULL because there is at least one element in the array
50 * when the array itself is non NULL.
52 #define __DO_TRACE(tp, proto, args) \
54 struct tracepoint_probe *__tp_it_probe_ptr; \
59 __tp_it_probe_ptr = rcu_dereference((tp)->probes); \
60 if (__tp_it_probe_ptr) { \
62 __tp_it_func = __tp_it_probe_ptr->func; \
63 __tp_cb_data = __tp_it_probe_ptr->data; \
64 ((void(*)(proto))__tp_it_func)(args); \
65 } while ((++__tp_it_probe_ptr)->func); \
70 #define TP_PARAMS(args...) args
71 #define TP_PROTO(args...) args
72 #define TP_ARGS(args...) args
74 #define __CHECK_TRACE(name, proto, args) \
76 if (unlikely(__tracepoint_##name.state)) \
77 __DO_TRACE(&__tracepoint_##name, \
78 TP_PROTO(proto), TP_ARGS(args)); \
82 * Make sure the alignment of the structure in the __tracepoints section will
83 * not add unwanted padding between the beginning of the section and the
84 * structure. Force alignment to the same alignment as the section start.
86 #define __DECLARE_TRACEPOINT(name, proto, args, data_proto, data_args) \
87 extern struct tracepoint __tracepoint_##name; \
88 static inline void __trace_##name(proto) \
90 __CHECK_TRACE(name, TP_PROTO(data_proto), \
91 TP_ARGS(data_args)); \
94 __register_trace_##name(void (*probe)(data_proto), void *data) \
96 return __tracepoint_probe_register(#name, (void *)probe,\
101 __unregister_trace_##name(void (*probe)(data_proto), void *data)\
103 return __tracepoint_probe_unregister(#name, (void *)probe, \
108 * The need for the _DECLARE_TRACEPOINT_NOARGS() is to handle the prototype
109 * (void). "void" is a special value in a function prototype and can
110 * not be combined with other arguments. Since the DECLARE_TRACEPOINT()
111 * macro adds a data element at the beginning of the prototype,
112 * we need a way to differentiate "(void *data, proto)" from
113 * "(void *data, void)". The second prototype is invalid.
115 * DECLARE_TRACEPOINT_NOARGS() passes "void" as the tracepoint prototype
116 * and "void *__tp_cb_data" as the callback prototype.
118 * DECLARE_TRACEPOINT() passes "proto" as the tracepoint protoype and
119 * "void *__tp_cb_data, proto" as the callback prototype.
121 #define _DECLARE_TRACEPOINT_NOARGS(name) \
122 __DECLARE_TRACEPOINT(name, void, , void *__tp_cb_data, __tp_cb_data)
124 #define _DECLARE_TRACEPOINT(name, proto, args) \
125 __DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args), \
126 TP_PARAMS(void *__tp_cb_data, proto), \
127 TP_PARAMS(__tp_cb_data, args))
130 * __tracepoints_ptrs section is not const (read-only) to let the linker update
131 * the pointer, allowing PIC code.
133 #define _DEFINE_TRACEPOINT(name) \
134 static const char __tpstrtab_##name[] \
135 __attribute__((section("__tracepoints_strings"))) = #name; \
136 struct tracepoint __tracepoint_##name \
137 __attribute__((section("__tracepoints"))) = \
138 { __tpstrtab_##name, 0, NULL }; \
139 static struct tracepoint * __tracepoint_ptr_##name \
140 __attribute__((used, section("__tracepoints_ptrs"))) = \
141 &__tracepoint_##name;
144 #define __register_tracepoint(name, probe, data) \
145 __register_trace_##name(probe, data)
146 #define __unregister_tracepoint(name, probe, data) \
147 __unregister_trace_##name(probe, data)
150 * Connect a probe to a tracepoint.
154 int __tracepoint_probe_register(const char *name
, void *probe
, void *data
);
157 * Disconnect a probe from a tracepoint.
161 int __tracepoint_probe_unregister(const char *name
, void *probe
, void *data
);
164 int tracepoint_register_lib(struct tracepoint
* const *tracepoints_start
,
165 int tracepoints_count
);
167 int tracepoint_unregister_lib(struct tracepoint
* const *tracepoints_start
);
170 * These weak symbols, the constructor, and destructor take care of
171 * registering only _one_ instance of the tracepoints per shared-ojbect
172 * (or for the whole main program).
173 * The dummy tracepoint entry ensures that the start/stop pointers get
174 * initialized by the linker when no tracepoints are present in a
175 * shared-object (or main program).
177 extern struct tracepoint
* const __start___tracepoints_ptrs
[]
178 __attribute__((weak
, visibility("hidden")));
179 extern struct tracepoint
* const __stop___tracepoints_ptrs
[]
180 __attribute__((weak
, visibility("hidden")));
181 int __tracepoint_registered
182 __attribute__((weak
, visibility("hidden")));
184 static void __attribute__((constructor
)) __tracepoints__init(void)
186 if (__tracepoint_registered
++)
188 tracepoint_register_lib(__start___tracepoints_ptrs
,
189 __stop___tracepoints_ptrs
-
190 __start___tracepoints_ptrs
);
193 static void __attribute__((destructor
)) __tracepoints__destroy(void)
195 if (--__tracepoint_registered
)
197 tracepoint_unregister_lib(__start___tracepoints_ptrs
);
200 #ifndef TRACEPOINT_EVENT
202 * Usage of the TRACEPOINT_EVENT macro:
204 * In short, an example:
206 * TRACEPOINT_EVENT(< [com_company_]project_[component_]event >,
207 * TP_PROTO(int arg0, void *arg1, char *string, size_t strlen,
208 * long *arg4, size_t arg4_len),
209 * TP_ARGS(arg0, arg1, string, strlen, arg4, arg4_len),
212 * * Integer, printed in base 10 *
213 * ctf_integer(int, field_a, arg0)
215 * * Integer, printed with 0x base 16 *
216 * ctf_integer_hex(unsigned long, field_d, arg1)
218 * * Array Sequence, printed as UTF8-encoded array of bytes *
219 * ctf_array_text(char, field_b, string, FIXED_LEN)
220 * ctf_sequence_text(char, field_c, string, size_t, strlen)
222 * * String, printed as UTF8-encoded string *
223 * ctf_string(field_e, string)
225 * * Array sequence of signed integer values *
226 * ctf_array(long, field_f, arg4, FIXED_LEN4)
227 * ctf_sequence(long, field_g, arg4, size_t, arg4_len)
233 * We define a tracepoint, its arguments, and its 'fast binary record'
236 * Firstly, name your tracepoint via TRACEPOINT_EVENT(name,
238 * The "name" MUST follow these rules to ensure no namespace clash
241 * For projects (applications and libraries) for which an entity
242 * specific to the project controls the source code and thus its
243 * tracepoints (typically with a scope larger than a single company):
246 * project_component_event
250 * Where "project" is the name of the project,
251 * "component" is the name of the project component (which may
252 * include several levels of sub-components, e.g.
253 * ...component_subcomponent_...) where the tracepoint is located
255 * "event" is the name of the tracepoint event.
257 * For projects issued from a single company wishing to advertise that
258 * the company controls the source code and thus the tracepoints, the
259 * "com_" prefix should be used:
262 * com_company_project_component_event
264 * com_company_project_event
266 * Where "company" is the name of the company,
267 * "project" is the name of the project,
268 * "component" is the name of the project component (which may
269 * include several levels of sub-components, e.g.
270 * ...component_subcomponent_...) where the tracepoint is located
272 * "event" is the name of the tracepoint event.
275 * As an example, let's consider a user-space application "someproject"
276 * that would have an internal thread scheduler:
278 * TRACEPOINT_EVENT(someproject_sched_switch,
281 * * A function has a regular function arguments
282 * * prototype, declare it via TP_PROTO():
285 * TP_PROTO(struct rq *rq, struct task_struct *prev,
286 * struct task_struct *next),
289 * * Define the call signature of the 'function'.
290 * * (Design sidenote: we use this instead of a
291 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
294 * TP_ARGS(rq, prev, next),
297 * * Fast binary tracing: define the trace record via
298 * * TP_FIELDS(). You can think about it like a
299 * * regular C structure local variable definition.
301 * * This is how the trace record is structured and will
302 * * be saved into the ring buffer. These are the fields
303 * * that will be exposed to readers.
305 * * ctf_integer(pid_t, prev_pid, prev->pid) is equivalent
306 * * to a standard declaraton:
310 * * followed by an assignment:
312 * * prev_pid = prev->pid;
314 * * ctf_array(char, prev_comm, prev->comm, TASK_COMM_LEN) is
317 * * char prev_comm[TASK_COMM_LEN];
319 * * followed by an assignment:
321 * * memcpy(prev_comm, prev->comm, TASK_COMM_LEN);
325 * ctf_array(char, prev_comm, prev->comm, TASK_COMM_LEN)
326 * ctf_integer(pid_t, prev_pid, prev->pid)
327 * ctf_integer(int, prev_prio, prev->prio)
328 * ctf_array(char, next_comm, next->comm, TASK_COMM_LEN)
329 * ctf_integer(pid_t, next_pid, next->pid)
330 * ctf_integer(int, next_prio, next->prio)
335 #define TRACEPOINT_EVENT(name, proto, args, fields) \
336 _DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args))
338 #define TRACEPOINT_EVENT_CLASS(name, proto, args, fields)
339 #define TRACEPOINT_EVENT_INSTANCE(template, name, proto, args) \
340 _DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args))
343 * Declaration of tracepoints that take 0 argument.
345 #define TRACEPOINT_EVENT_NOARGS(name, fields) \
346 _DECLARE_TRACEPOINT_NOARGS(name)
348 #define TRACEPOINT_EVENT_CLASS_NOARGS(name, fields)
349 #define TRACEPOINT_EVENT_INSTANCE_NOARGS(template, name) \
350 _DECLARE_TRACEPOINT_NOARGS(name)
352 #endif /* #ifndef TRACEPOINT_EVENT */
354 #endif /* _UST_TRACEPOINT_H */