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1#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;
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.
32 */
33
34#define TPPROTO(args...) args
35#define TPARGS(args...) args
36
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 \
47 rcu_read_lock_sched_notrace(); \
48 it_func = rcu_dereference((tp)->funcs); \
49 if (it_func) { \
50 do { \
51 ((void(*)(proto))(*it_func))(args); \
52 } while (*(++it_func)); \
53 } \
54 rcu_read_unlock_sched_notrace(); \
55 } 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 */
62#define DECLARE_TRACE(name, proto, args) \
63 extern struct tracepoint __tracepoint_##name; \
64 static inline void trace_##name(proto) \
65 { \
66 if (unlikely(__tracepoint_##name.state)) \
67 __DO_TRACE(&__tracepoint_##name, \
68 TPPROTO(proto), TPARGS(args)); \
69 } \
70 static inline int register_trace_##name(void (*probe)(proto)) \
71 { \
72 return tracepoint_probe_register(#name, (void *)probe); \
73 } \
74 static inline int unregister_trace_##name(void (*probe)(proto)) \
75 { \
76 return tracepoint_probe_unregister(#name, (void *)probe);\
77 }
78
79#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
91extern void tracepoint_update_probe_range(struct tracepoint *begin,
92 struct tracepoint *end);
93
94#else /* !CONFIG_TRACEPOINTS */
95#define DECLARE_TRACE(name, proto, args) \
96 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 } \
104 static inline int unregister_trace_##name(void (*probe)(proto)) \
105 { \
106 return -ENOSYS; \
107 }
108
109#define DEFINE_TRACE(name)
110#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
111#define EXPORT_TRACEPOINT_SYMBOL(name)
112
113static 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
130extern 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
134struct 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
146/*
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 */
151static inline void tracepoint_synchronize_unregister(void)
152{
153 synchronize_sched();
154}
155
156#endif