LXR linux/include/linux/tracepoint.h

   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
 157