include/lttng/tracepoint.h

   1 #ifndef _LTTNG_TRACEPOINT_H
   2 #define _LTTNG_TRACEPOINT_H
   3
   4 /*
   5  * Copyright (c) 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  *
   7  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   8  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   9  *
  10  * Permission is hereby granted to use or copy this program
  11  * for any purpose,  provided the above notices are retained on all copies.
  12  * Permission to modify the code and to distribute modified code is granted,
  13  * provided the above notices are retained, and a notice that the code was
  14  * modified is included with the above copyright notice.
  15  */
  16
  17 #include <urcu-bp.h>
  18 #include <tracepoint-types.h>
  19 #include <urcu/compiler.h>
  20
  21 #ifdef __cplusplus
  22 extern "C" {
  23 #endif
  24
  25 #define tracepoint(provider, name, ...)                                     \
  26         do {                                                                \
  27                 if (caa_unlikely(__tracepoint_##provider##___##name.state)) \
  28                         __tracepoint_cb_##provider##___##name(__VA_ARGS__); \
  29         } while (0)
  30
  31 #define TP_ARGS(...)       __VA_ARGS__
  32
  33 /*
  34  * TP_ARGS takes tuples of type, argument separated by a comma.
  35  * It can take up to 10 tuples (which means that less than 10 tuples is
  36  * fine too).
  37  * Each tuple is also separated by a comma.
  38  */
  39 #define _TP_COMBINE_TOKENS1(_tokena, _tokenb)       _tokena##_tokenb
  40 #define _TP_COMBINE_TOKENS(_tokena, _tokenb)        _TP_COMBINE_TOKENS1(_tokena, _tokenb)
  41
  42 /* _TP_EXVAR* extract the var names. */
  43 #define _TP_EXVAR0()
  44 #define _TP_EXVAR2(a,b)                                         b
  45 #define _TP_EXVAR4(a,b,c,d)                                     b,d
  46 #define _TP_EXVAR6(a,b,c,d,e,f)                                 b,d,f
  47 #define _TP_EXVAR8(a,b,c,d,e,f,g,h)                             b,d,f,h
  48 #define _TP_EXVAR10(a,b,c,d,e,f,g,h,i,j)                        b,d,f,h,j
  49 #define _TP_EXVAR12(a,b,c,d,e,f,g,h,i,j,k,l)                    b,d,f,h,j,l
  50 #define _TP_EXVAR14(a,b,c,d,e,f,g,h,i,j,k,l,m,n)                b,d,f,h,j,l,n
  51 #define _TP_EXVAR16(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p)            b,d,f,h,j,l,n,p
  52 #define _TP_EXVAR18(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r)        b,d,f,h,j,l,n,p,r
  53 #define _TP_EXVAR20(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t)    b,d,f,h,j,l,n,p,r,t
  54
  55 #define _TP_EXDATA_VAR0()                                               __tp_data
  56 #define _TP_EXDATA_VAR2(a,b)                                            __tp_data,b
  57 #define _TP_EXDATA_VAR4(a,b,c,d)                                        __tp_data,b,d
  58 #define _TP_EXDATA_VAR6(a,b,c,d,e,f)                                    __tp_data,b,d,f
  59 #define _TP_EXDATA_VAR8(a,b,c,d,e,f,g,h)                                __tp_data,b,d,f,h
  60 #define _TP_EXDATA_VAR10(a,b,c,d,e,f,g,h,i,j)                           __tp_data,b,d,f,h,j
  61 #define _TP_EXDATA_VAR12(a,b,c,d,e,f,g,h,i,j,k,l)                       __tp_data,b,d,f,h,j,l
  62 #define _TP_EXDATA_VAR14(a,b,c,d,e,f,g,h,i,j,k,l,m,n)                   __tp_data,b,d,f,h,j,l,n
  63 #define _TP_EXDATA_VAR16(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p)               __tp_data,b,d,f,h,j,l,n,p
  64 #define _TP_EXDATA_VAR18(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r)           __tp_data,b,d,f,h,j,l,n,p,r
  65 #define _TP_EXDATA_VAR20(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t)       __tp_data,b,d,f,h,j,l,n,p,r,t
  66
  67 /* _TP_EXPROTO* extract tuples of type, var */
  68 #define _TP_EXPROTO0()
  69 #define _TP_EXPROTO2(a,b)                                       a b
  70 #define _TP_EXPROTO4(a,b,c,d)                                   a b,c d
  71 #define _TP_EXPROTO6(a,b,c,d,e,f)                               a b,c d,e f
  72 #define _TP_EXPROTO8(a,b,c,d,e,f,g,h)                           a b,c d,e f,g h
  73 #define _TP_EXPROTO10(a,b,c,d,e,f,g,h,i,j)                      a b,c d,e f,g h,i j
  74 #define _TP_EXPROTO12(a,b,c,d,e,f,g,h,i,j,k,l)                  a b,c d,e f,g h,i j,k l
  75 #define _TP_EXPROTO14(a,b,c,d,e,f,g,h,i,j,k,l,m,n)              a b,c d,e f,g h,i j,k l,m n
  76 #define _TP_EXPROTO16(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p)          a b,c d,e f,g h,i j,k l,m n,o p
  77 #define _TP_EXPROTO18(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r)      a b,c d,e f,g h,i j,k l,m n,o p,q r
  78 #define _TP_EXPROTO20(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t)  a b,c d,e f,g h,i j,k l,m n,o p,q r,s t
  79
  80 #define _TP_EXDATA_PROTO0()                                             void *__tp_data
  81 #define _TP_EXDATA_PROTO2(a,b)                                          void *__tp_data,a b
  82 #define _TP_EXDATA_PROTO4(a,b,c,d)                                      void *__tp_data,a b,c d
  83 #define _TP_EXDATA_PROTO6(a,b,c,d,e,f)                                  void *__tp_data,a b,c d,e f
  84 #define _TP_EXDATA_PROTO8(a,b,c,d,e,f,g,h)                              void *__tp_data,a b,c d,e f,g h
  85 #define _TP_EXDATA_PROTO10(a,b,c,d,e,f,g,h,i,j)                         void *__tp_data,a b,c d,e f,g h,i j
  86 #define _TP_EXDATA_PROTO12(a,b,c,d,e,f,g,h,i,j,k,l)                     void *__tp_data,a b,c d,e f,g h,i j,k l
  87 #define _TP_EXDATA_PROTO14(a,b,c,d,e,f,g,h,i,j,k,l,m,n)                 void *__tp_data,a b,c d,e f,g h,i j,k l,m n
  88 #define _TP_EXDATA_PROTO16(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p)             void *__tp_data,a b,c d,e f,g h,i j,k l,m n,o p
  89 #define _TP_EXDATA_PROTO18(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r)         void *__tp_data,a b,c d,e f,g h,i j,k l,m n,o p,q r
  90 #define _TP_EXDATA_PROTO20(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t)     void *__tp_data,a b,c d,e f,g h,i j,k l,m n,o p,q r,s t
  91
  92 /* Preprocessor trick to count arguments. Inspired from sdt.h. */
  93 #define _TP_NARGS(...)                  __TP_NARGS(__VA_ARGS__, 20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0)
  94 #define __TP_NARGS(_0,_1,_2,_3,_4,_5,_6,_7,_8,_9,_10,_11,_12,_13,_14,_15,_16,_17,_18,_19,_20, N, ...)   N
  95 #define _TP_PROTO_N(N, ...)             _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXPROTO, N)(__VA_ARGS__))
  96 #define _TP_VAR_N(N, ...)               _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXVAR, N)(__VA_ARGS__))
  97 #define _TP_DATA_PROTO_N(N, ...)        _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXDATA_PROTO, N)(__VA_ARGS__))
  98 #define _TP_DATA_VAR_N(N, ...)          _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXDATA_VAR, N)(__VA_ARGS__))
  99 #define _TP_ARGS_PROTO(...)             _TP_PROTO_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 100 #define _TP_ARGS_VAR(...)               _TP_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 101 #define _TP_ARGS_DATA_PROTO(...)        _TP_DATA_PROTO_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 102 #define _TP_ARGS_DATA_VAR(...)          _TP_DATA_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 103 #define _TP_PARAMS(...)                 __VA_ARGS__
 104
 105 #define _DECLARE_TRACEPOINT(provider, name, ...)                                        \
 106 extern struct tracepoint __tracepoint_##provider##___##name;                            \
 107 static inline void __tracepoint_cb_##provider##___##name(_TP_ARGS_PROTO(__VA_ARGS__))   \
 108 {                                                                                       \
 109         struct tracepoint_probe *__tp_probe;                                            \
 110                                                                                         \
 111         rcu_read_lock_bp();                                                             \
 112         __tp_probe = rcu_dereference(__tracepoint_##provider##___##name.probes);        \
 113         if (caa_unlikely(!__tp_probe))                                                  \
 114                 goto end;                                                               \
 115         do {                                                                            \
 116                 void *__tp_cb = __tp_probe->func;                                       \
 117                 void *__tp_data = __tp_probe->data;                                     \
 118                                                                                         \
 119                 URCU_FORCE_CAST(void (*)(_TP_ARGS_DATA_PROTO(__VA_ARGS__)), __tp_cb)    \
 120                                 (_TP_ARGS_DATA_VAR(__VA_ARGS__));                       \
 121         } while ((++__tp_probe)->func);                                                 \
 122 end:                                                                                    \
 123         rcu_read_unlock_bp();                                                           \
 124 }                                                                                       \
 125 static inline void __tracepoint_register_##provider##___##name(char *name,              \
 126                 void *func, void *data)                                                 \
 127 {                                                                                       \
 128         __tracepoint_probe_register(name, func, data);                                  \
 129 }                                                                                       \
 130 static inline void __tracepoint_unregister_##provider##___##name(char *name,            \
 131                 void *func, void *data)                                                 \
 132 {                                                                                       \
 133         __tracepoint_probe_unregister(name, func, data);                                \
 134 }
 135
 136 /*
 137  * Note: to allow PIC code, we need to allow the linker to update the pointers
 138  * in the __tracepoints_ptrs section.
 139  * Therefore, this section is _not_ const (read-only).
 140  */
 141 #define _DEFINE_TRACEPOINT(provider, name)                                      \
 142         static const char __tp_strtab_##provider##___##name[]                   \
 143                 __attribute__((section("__tracepoints_strings"))) =             \
 144                         #provider ":" #name;                                    \
 145         struct tracepoint __tracepoint_##provider##___##name                    \
 146                 __attribute__((section("__tracepoints"))) =                     \
 147                         { __tp_strtab_##provider##___##name, 0, NULL };         \
 148         static struct tracepoint * __tracepoint_ptr_##provider##___##name       \
 149                 __attribute__((used, section("__tracepoints_ptrs"))) =          \
 150                         &__tracepoint_##provider##___##name;
 151
 152 extern int __tracepoint_probe_register(const char *name, void *func, void *data);
 153 extern int __tracepoint_probe_unregister(const char *name, void *func, void *data);
 154 extern int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
 155                 int tracepoints_count);
 156 extern int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start);
 157
 158 /*
 159  * These weak symbols, the constructor, and destructor take care of
 160  * registering only _one_ instance of the tracepoints per shared-ojbect
 161  * (or for the whole main program).
 162  */
 163 extern struct tracepoint * const __start___tracepoints_ptrs[]
 164         __attribute__((weak, visibility("hidden")));
 165 extern struct tracepoint * const __stop___tracepoints_ptrs[]
 166         __attribute__((weak, visibility("hidden")));
 167 int __tracepoint_registered
 168         __attribute__((weak, visibility("hidden")));
 169
 170 static void __attribute__((constructor)) __tracepoints__init(void)
 171 {
 172         if (__tracepoint_registered++)
 173                 return;
 174         tracepoint_register_lib(__start___tracepoints_ptrs,
 175                                 __stop___tracepoints_ptrs -
 176                                 __start___tracepoints_ptrs);
 177 }
 178
 179 static void __attribute__((destructor)) __tracepoints__destroy(void)
 180 {
 181         if (--__tracepoint_registered)
 182                 return;
 183         tracepoint_unregister_lib(__start___tracepoints_ptrs);
 184 }
 185
 186 #ifdef __cplusplus
 187 }
 188 #endif
 189
 190 #endif /* _LTTNG_TRACEPOINT_H */
 191
 192 /* The following declarations must be outside re-inclusion protection. */
 193
 194 #ifndef TRACEPOINT_EVENT
 195
 196 /*
 197  * How to use the TRACEPOINT_EVENT macro:
 198  *
 199  * An example:
 200  *
 201  * TRACEPOINT_EVENT(someproject_component, event_name,
 202  *
 203  *     * TP_ARGS takes from 0 to 10 "type, field_name" pairs *
 204  *
 205  *     TP_ARGS(int, arg0, void *, arg1, char *, string, size_t, strlen,
 206  *             long *, arg4, size_t, arg4_len),
 207  *
 208  *      * TP_FIELDS describes the event payload layout in the trace *
 209  *
 210  *     TP_FIELDS(
 211  *         * Integer, printed in base 10 *
 212  *         ctf_integer(int, field_a, arg0)
 213  *
 214  *         * Integer, printed with 0x base 16 *
 215  *         ctf_integer_hex(unsigned long, field_d, arg1)
 216  *
 217  *         * Array Sequence, printed as UTF8-encoded array of bytes *
 218  *         ctf_array_text(char, field_b, string, FIXED_LEN)
 219  *         ctf_sequence_text(char, field_c, string, size_t, strlen)
 220  *
 221  *         * String, printed as UTF8-encoded string *
 222  *         ctf_string(field_e, string)
 223  *
 224  *         * Array sequence of signed integer values *
 225  *         ctf_array(long, field_f, arg4, FIXED_LEN4)
 226  *         ctf_sequence(long, field_g, arg4, size_t, arg4_len)
 227  *     )
 228  * )
 229  *
 230  * More detailed explanation:
 231  *
 232  * The name of the tracepoint is expressed as a tuple with the provider
 233  * and name arguments.
 234  *
 235  * The provider and name should be a proper C99 identifier.
 236  * The "provider" and "name" MUST follow these rules to ensure no
 237  * namespace clash occurs:
 238  *
 239  * For projects (applications and libraries) for which an entity
 240  * specific to the project controls the source code and thus its
 241  * tracepoints (typically with a scope larger than a single company):
 242  *
 243  * either:
 244  *   project_component, event
 245  * or:
 246  *   project, event
 247  *
 248  * Where "project" is the name of the project,
 249  *       "component" is the name of the project component (which may
 250  *       include several levels of sub-components, e.g.
 251  *       ...component_subcomponent_...) where the tracepoint is located
 252  *       (optional),
 253  *       "event" is the name of the tracepoint event.
 254  *
 255  * For projects issued from a single company wishing to advertise that
 256  * the company controls the source code and thus the tracepoints, the
 257  * "com_" prefix should be used:
 258  *
 259  * either:
 260  *   com_company_project_component, event
 261  * or:
 262  *   com_company_project, event
 263  *
 264  * Where "company" is the name of the company,
 265  *       "project" is the name of the project,
 266  *       "component" is the name of the project component (which may
 267  *       include several levels of sub-components, e.g.
 268  *       ...component_subcomponent_...) where the tracepoint is located
 269  *       (optional),
 270  *       "event" is the name of the tracepoint event.
 271  *
 272  * the provider:event identifier is limited to 127 characters.
 273  */
 274
 275
 276 #define TRACEPOINT_EVENT(provider, name, args, fields)                  \
 277         _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))
 278
 279 #define TRACEPOINT_EVENT_CLASS(provider, name, args, fields)
 280
 281 #define TRACEPOINT_EVENT_INSTANCE(provider, _template, name, args)      \
 282         _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))
 283
 284 #endif /* #ifndef TRACEPOINT_EVENT */
 285
 286 #ifndef TRACEPOINT_LOGLEVEL
 287
 288 /*
 289  * Tracepoint Loglevel Declaration Facility
 290  *
 291  * This is a place-holder the tracepoint loglevel declaration,
 292  * overridden by the tracer implementation.
 293  *
 294  * Typical use of these loglevels:
 295  *
 296  * 1) Declare the mapping between loglevel names and an integer values
 297  *    within TRACEPOINT_LOGLEVEL_ENUM, using TP_LOGLEVEL for each tuple.
 298  *    Do _NOT_ add comma (,) nor semicolon (;) between the
 299  *    TRACEPOINT_LOGLEVEL_ENUM entries. Do _NOT_ add comma (,) nor
 300  *    semicolon (;) after the TRACEPOINT_LOGLEVEL_ENUM declaration.  The
 301  *    name should be a proper C99 identifier.
 302  *
 303  *      TRACEPOINT_LOGLEVEL_ENUM(
 304  *              TP_LOGLEVEL( < loglevel_name >, < value > )
 305  *              TP_LOGLEVEL( < loglevel_name >, < value > )
 306  *              ...
 307  *      )
 308  *
 309  *    e.g.:
 310  *
 311  *      TRACEPOINT_LOGLEVEL_ENUM(
 312  *              TP_LOGLEVEL(LOG_EMERG,   0)
 313  *              TP_LOGLEVEL(LOG_ALERT,   1)
 314  *              TP_LOGLEVEL(LOG_CRIT,    2)
 315  *              TP_LOGLEVEL(LOG_ERR,     3)
 316  *              TP_LOGLEVEL(LOG_WARNING, 4)
 317  *              TP_LOGLEVEL(LOG_NOTICE,  5)
 318  *              TP_LOGLEVEL(LOG_INFO,    6)
 319  *              TP_LOGLEVEL(LOG_DEBUG,   7)
 320  *      )
 321  *
 322  * 2) Then, declare tracepoint loglevels for tracepoints. A
 323  *    TRACEPOINT_EVENT should be declared prior to the the
 324  *    TRACEPOINT_LOGLEVEL for a given tracepoint name. The first field
 325  *    is the name of the tracepoint, the second field is the loglevel
 326  *    name.
 327  *
 328  *      TRACEPOINT_LOGLEVEL(< [com_company_]project[_component] >, < event >,
 329  *              < loglevel_name >)
 330  *
 331  * The TRACEPOINT_PROVIDER must be defined when declaring a
 332  * TRACEPOINT_LOGLEVEL_ENUM and TRACEPOINT_LOGLEVEL. The tracepoint
 333  * loglevel enumeration apply to the entire TRACEPOINT_PROVIDER. Only one
 334  * tracepoint loglevel enumeration should be declared per tracepoint
 335  * provider.
 336  */
 337
 338 #define TRACEPOINT_LOGLEVEL_ENUM()
 339 #define TRACEPOINT_LOGLEVEL(name, loglevel)
 340
 341 #endif /* #ifndef TRACEPOINT_LOGLEVEL */