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(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
  91 extern 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
 113 static 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  */
 122 extern 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  */
 128 extern int tracepoint_probe_unregister(const char *name, void *probe);
 129
 130 extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
 131 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
 132 extern void tracepoint_probe_update_all(void);
 133
 134 struct tracepoint_iter {
 135         struct module *module;
 136         struct tracepoint *tracepoint;
 137 };
 138
 139 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
 140 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
 141 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
 142 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
 143 extern 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  */
 151 static inline void tracepoint_synchronize_unregister(void)
 152 {
 153         synchronize_sched();
 154 }
 155
 156 #endif