1 #ifndef _LINUX_TRACEPOINT_H
2 #define _LINUX_TRACEPOINT_H
5 * Kernel Tracepoint API.
7 * See Documentation/tracepoint.txt.
9 * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
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/types.h>
18 #include <linux/rcupdate.h>
24 const char *name; /* Tracepoint name */
25 int state; /* State. */
27 } __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.
36 #define TP_PROTO(args...) args
37 #define TP_ARGS(args...) args
39 #ifdef CONFIG_TRACEPOINTS
42 * it_func[0] is never NULL because there is at least one element in the array
43 * when the array itself is non NULL.
45 #define __DO_TRACE(tp, proto, args) \
49 rcu_read_lock_sched_notrace(); \
50 it_func = rcu_dereference((tp)->funcs); \
53 ((void(*)(proto))(*it_func))(args); \
54 } while (*(++it_func)); \
56 rcu_read_unlock_sched_notrace(); \
60 * Make sure the alignment of the structure in the __tracepoints section will
61 * not add unwanted padding between the beginning of the section and the
62 * structure. Force alignment to the same alignment as the section start.
63 * An optional set of (un)registration functions can be passed to perform any
64 * additional (un)registration work.
66 #define DECLARE_TRACE_WITH_CALLBACK(name, proto, args, reg, unreg) \
67 extern struct tracepoint __tracepoint_##name; \
68 static inline void trace_##name(proto) \
70 if (unlikely(__tracepoint_##name.state)) \
71 __DO_TRACE(&__tracepoint_##name, \
72 TP_PROTO(proto), TP_ARGS(args)); \
74 static inline int register_trace_##name(void (*probe)(proto)) \
77 void (*func)(void) = reg; \
79 ret = tracepoint_probe_register(#name, (void *)probe); \
84 static inline int unregister_trace_##name(void (*probe)(proto)) \
87 void (*func)(void) = unreg; \
89 ret = tracepoint_probe_unregister(#name, (void *)probe);\
96 #define DECLARE_TRACE(name, proto, args) \
97 DECLARE_TRACE_WITH_CALLBACK(name, TP_PROTO(proto), TP_ARGS(args),\
100 #define DEFINE_TRACE(name) \
101 static const char __tpstrtab_##name[] \
102 __attribute__((section("__tracepoints_strings"))) = #name; \
103 struct tracepoint __tracepoint_##name \
104 __attribute__((section("__tracepoints"), aligned(32))) = \
105 { __tpstrtab_##name, 0, NULL }
107 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
108 EXPORT_SYMBOL_GPL(__tracepoint_##name)
109 #define EXPORT_TRACEPOINT_SYMBOL(name) \
110 EXPORT_SYMBOL(__tracepoint_##name)
112 extern void tracepoint_update_probe_range(struct tracepoint *begin,
113 struct tracepoint *end);
115 #else /* !CONFIG_TRACEPOINTS */
116 #define DECLARE_TRACE_WITH_CALLBACK(name, proto, args, reg, unreg) \
117 static inline void _do_trace_##name(struct tracepoint *tp, proto) \
119 static inline void trace_##name(proto) \
121 static inline int register_trace_##name(void (*probe)(proto)) \
125 static inline int unregister_trace_##name(void (*probe)(proto)) \
130 #define DECLARE_TRACE(name, proto, args) \
131 DECLARE_TRACE_WITH_CALLBACK(name, TP_PROTO(proto), TP_ARGS(args),\
134 #define DEFINE_TRACE(name)
135 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
136 #define EXPORT_TRACEPOINT_SYMBOL(name)
138 static inline void tracepoint_update_probe_range(struct tracepoint *begin,
139 struct tracepoint *end)
141 #endif /* CONFIG_TRACEPOINTS */
142 #endif /* DECLARE_TRACE */
145 * Connect a probe to a tracepoint.
146 * Internal API, should not be used directly.
148 extern int tracepoint_probe_register(const char *name, void *probe);
151 * Disconnect a probe from a tracepoint.
152 * Internal API, should not be used directly.
154 extern int tracepoint_probe_unregister(const char *name, void *probe);
156 extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
157 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
158 extern void tracepoint_probe_update_all(void);
160 struct tracepoint_iter {
161 struct module *module;
162 struct tracepoint *tracepoint;
165 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
166 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
167 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
168 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
169 extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
170 struct tracepoint *begin, struct tracepoint *end);
173 * tracepoint_synchronize_unregister must be called between the last tracepoint
174 * probe unregistration and the end of module exit to make sure there is no
175 * caller executing a probe when it is freed.
177 static inline void tracepoint_synchronize_unregister(void)
182 #define PARAMS(args...) args
186 * For use with the TRACE_EVENT macro:
188 * We define a tracepoint, its arguments, its printk format
189 * and its 'fast binay record' layout.
191 * Firstly, name your tracepoint via TRACE_EVENT(name : the
192 * 'subsystem_event' notation is fine.
194 * Think about this whole construct as the
195 * 'trace_sched_switch() function' from now on.
198 * TRACE_EVENT(sched_switch,
201 * * A function has a regular function arguments
202 * * prototype, declare it via TP_PROTO():
205 * TP_PROTO(struct rq *rq, struct task_struct *prev,
206 * struct task_struct *next),
209 * * Define the call signature of the 'function'.
210 * * (Design sidenote: we use this instead of a
211 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
214 * TP_ARGS(rq, prev, next),
217 * * Fast binary tracing: define the trace record via
218 * * TP_STRUCT__entry(). You can think about it like a
219 * * regular C structure local variable definition.
221 * * This is how the trace record is structured and will
222 * * be saved into the ring buffer. These are the fields
223 * * that will be exposed to user-space in
224 * * /sys/kernel/debug/tracing/events/<*>/format.
226 * * The declared 'local variable' is called '__entry'
228 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
232 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
234 * * char prev_comm[TASK_COMM_LEN];
238 * __array( char, prev_comm, TASK_COMM_LEN )
239 * __field( pid_t, prev_pid )
240 * __field( int, prev_prio )
241 * __array( char, next_comm, TASK_COMM_LEN )
242 * __field( pid_t, next_pid )
243 * __field( int, next_prio )
247 * * Assign the entry into the trace record, by embedding
248 * * a full C statement block into TP_fast_assign(). You
249 * * can refer to the trace record as '__entry' -
250 * * otherwise you can put arbitrary C code in here.
252 * * Note: this C code will execute every time a trace event
253 * * happens, on an active tracepoint.
257 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
258 * __entry->prev_pid = prev->pid;
259 * __entry->prev_prio = prev->prio;
260 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
261 * __entry->next_pid = next->pid;
262 * __entry->next_prio = next->prio;
266 * * Formatted output of a trace record via TP_printk().
267 * * This is how the tracepoint will appear under ftrace
268 * * plugins that make use of this tracepoint.
270 * * (raw-binary tracing wont actually perform this step.)
273 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
274 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
275 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
279 * This macro construct is thus used for the regular printk format
280 * tracing setup, it is used to construct a function pointer based
281 * tracepoint callback (this is used by programmatic plugins and
282 * can also by used by generic instrumentation like SystemTap), and
283 * it is also used to expose a structured trace record in
284 * /sys/kernel/debug/tracing/events/.
287 #define TRACE_EVENT(name, proto, args, struct, assign, print) \
288 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))