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
  20 struct module;
  21 struct tracepoint;
  22
  23 struct tracepoint {
  24         const char *name;               /* Tracepoint name */
  25         int state;                      /* State. */
  26         void **funcs;
  27 } __attribute__((aligned(8)));
  28
  29
  30 #define TPPROTO(args...)        args
  31 #define TPARGS(args...)         args
  32
  33 #ifdef CONFIG_TRACEPOINTS
  34
  35 /*
  36  * it_func[0] is never NULL because there is at least one element in the array
  37  * when the array itself is non NULL.
  38  */
  39 #define __DO_TRACE(tp, proto, args)                                     \
  40         do {                                                            \
  41                 void **it_func;                                         \
  42                                                                         \
  43                 rcu_read_lock_sched();                                  \
  44                 it_func = rcu_dereference((tp)->funcs);                 \
  45                 if (it_func) {                                          \
  46                         do {                                            \
  47                                 ((void(*)(proto))(*it_func))(args);     \
  48                         } while (*(++it_func));                         \
  49                 }                                                       \
  50                 rcu_read_unlock_sched();                                \
  51         } while (0)
  52
  53 /*
  54  * Make sure the alignment of the structure in the __tracepoints section will
  55  * not add unwanted padding between the beginning of the section and the
  56  * structure. Force alignment to the same alignment as the section start.
  57  */
  58 #define DEFINE_TRACE(name, proto, args)                                 \
  59         static inline void trace_##name(proto)                          \
  60         {                                                               \
  61                 static const char __tpstrtab_##name[]                   \
  62                 __attribute__((section("__tracepoints_strings")))       \
  63                 = #name ":" #proto;                                     \
  64                 static struct tracepoint __tracepoint_##name            \
  65                 __attribute__((section("__tracepoints"), aligned(8))) = \
  66                 { __tpstrtab_##name, 0, NULL };                         \
  67                 if (unlikely(__tracepoint_##name.state))                \
  68                         __DO_TRACE(&__tracepoint_##name,                \
  69                                 TPPROTO(proto), TPARGS(args));          \
  70         }                                                               \
  71         static inline int register_trace_##name(void (*probe)(proto))   \
  72         {                                                               \
  73                 return tracepoint_probe_register(#name ":" #proto,      \
  74                         (void *)probe);                                 \
  75         }                                                               \
  76         static inline void unregister_trace_##name(void (*probe)(proto))\
  77         {                                                               \
  78                 tracepoint_probe_unregister(#name ":" #proto,           \
  79                         (void *)probe);                                 \
  80         }
  81
  82 extern void tracepoint_update_probe_range(struct tracepoint *begin,
  83         struct tracepoint *end);
  84
  85 #else /* !CONFIG_TRACEPOINTS */
  86 #define DEFINE_TRACE(name, proto, args)                 \
  87         static inline void _do_trace_##name(struct tracepoint *tp, proto) \
  88         { }                                                             \
  89         static inline void trace_##name(proto)                          \
  90         { }                                                             \
  91         static inline int register_trace_##name(void (*probe)(proto))   \
  92         {                                                               \
  93                 return -ENOSYS;                                         \
  94         }                                                               \
  95         static inline void unregister_trace_##name(void (*probe)(proto))\
  96         { }
  97
  98 static inline void tracepoint_update_probe_range(struct tracepoint *begin,
  99         struct tracepoint *end)
 100 { }
 101 #endif /* CONFIG_TRACEPOINTS */
 102
 103 /*
 104  * Connect a probe to a tracepoint.
 105  * Internal API, should not be used directly.
 106  */
 107 extern int tracepoint_probe_register(const char *name, void *probe);
 108
 109 /*
 110  * Disconnect a probe from a tracepoint.
 111  * Internal API, should not be used directly.
 112  */
 113 extern int tracepoint_probe_unregister(const char *name, void *probe);
 114
 115 struct tracepoint_iter {
 116         struct module *module;
 117         struct tracepoint *tracepoint;
 118 };
 119
 120 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
 121 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
 122 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
 123 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
 124 extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
 125         struct tracepoint *begin, struct tracepoint *end);
 126
 127 /*
 128  * tracepoint_synchronize_unregister must be called between the last tracepoint
 129  * probe unregistration and the end of module exit to make sure there is no
 130  * caller executing a probe when it is freed.
 131  */
 132 static inline void tracepoint_synchronize_unregister(void)
 133 {
 134         synchronize_sched();
 135 }
 136
 137 #endif