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 <lttng/tracepoint-types.h>
  18 #include <lttng/tracepoint-rcu.h>
  19 #include <urcu/compiler.h>
  20 #include <dlfcn.h>      /* for dlopen */
  21 #include <assert.h>
  22
  23 #ifdef __cplusplus
  24 extern "C" {
  25 #endif
  26
  27 #define tracepoint(provider, name, ...)                                     \
  28         do {                                                                \
  29                 if (caa_unlikely(__tracepoint_##provider##___##name.state)) \
  30                         __tracepoint_cb_##provider##___##name(__VA_ARGS__); \
  31         } while (0)
  32
  33 #define TP_ARGS(...)       __VA_ARGS__
  34
  35 /*
  36  * TP_ARGS takes tuples of type, argument separated by a comma.
  37  * It can take up to 10 tuples (which means that less than 10 tuples is
  38  * fine too).
  39  * Each tuple is also separated by a comma.
  40  */
  41 #define __TP_COMBINE_TOKENS(_tokena, _tokenb)                           \
  42                 _tokena##_tokenb
  43 #define _TP_COMBINE_TOKENS(_tokena, _tokenb)                            \
  44                 __TP_COMBINE_TOKENS(_tokena, _tokenb)
  45 #define __TP_COMBINE_TOKENS3(_tokena, _tokenb, _tokenc)                 \
  46                 _tokena##_tokenb##_tokenc
  47 #define _TP_COMBINE_TOKENS3(_tokena, _tokenb, _tokenc)                  \
  48                 __TP_COMBINE_TOKENS3(_tokena, _tokenb, _tokenc)
  49 #define __TP_COMBINE_TOKENS4(_tokena, _tokenb, _tokenc, _tokend)        \
  50                 _tokena##_tokenb##_tokenc##_tokend
  51 #define _TP_COMBINE_TOKENS4(_tokena, _tokenb, _tokenc, _tokend)         \
  52                 __TP_COMBINE_TOKENS4(_tokena, _tokenb, _tokenc, _tokend)
  53
  54 /* _TP_EXVAR* extract the var names. */
  55 #define _TP_EXVAR0()
  56 #define _TP_EXVAR2(a,b)                                         b
  57 #define _TP_EXVAR4(a,b,c,d)                                     b,d
  58 #define _TP_EXVAR6(a,b,c,d,e,f)                                 b,d,f
  59 #define _TP_EXVAR8(a,b,c,d,e,f,g,h)                             b,d,f,h
  60 #define _TP_EXVAR10(a,b,c,d,e,f,g,h,i,j)                        b,d,f,h,j
  61 #define _TP_EXVAR12(a,b,c,d,e,f,g,h,i,j,k,l)                    b,d,f,h,j,l
  62 #define _TP_EXVAR14(a,b,c,d,e,f,g,h,i,j,k,l,m,n)                b,d,f,h,j,l,n
  63 #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
  64 #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
  65 #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
  66
  67 #define _TP_EXDATA_VAR0()                                               __tp_data
  68 #define _TP_EXDATA_VAR2(a,b)                                            __tp_data,b
  69 #define _TP_EXDATA_VAR4(a,b,c,d)                                        __tp_data,b,d
  70 #define _TP_EXDATA_VAR6(a,b,c,d,e,f)                                    __tp_data,b,d,f
  71 #define _TP_EXDATA_VAR8(a,b,c,d,e,f,g,h)                                __tp_data,b,d,f,h
  72 #define _TP_EXDATA_VAR10(a,b,c,d,e,f,g,h,i,j)                           __tp_data,b,d,f,h,j
  73 #define _TP_EXDATA_VAR12(a,b,c,d,e,f,g,h,i,j,k,l)                       __tp_data,b,d,f,h,j,l
  74 #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
  75 #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
  76 #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
  77 #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
  78
  79 /* _TP_EXPROTO* extract tuples of type, var */
  80 #define _TP_EXPROTO0()
  81 #define _TP_EXPROTO2(a,b)                                       a b
  82 #define _TP_EXPROTO4(a,b,c,d)                                   a b,c d
  83 #define _TP_EXPROTO6(a,b,c,d,e,f)                               a b,c d,e f
  84 #define _TP_EXPROTO8(a,b,c,d,e,f,g,h)                           a b,c d,e f,g h
  85 #define _TP_EXPROTO10(a,b,c,d,e,f,g,h,i,j)                      a b,c d,e f,g h,i j
  86 #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
  87 #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
  88 #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
  89 #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
  90 #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
  91
  92 #define _TP_EXDATA_PROTO0()                                             void *__tp_data
  93 #define _TP_EXDATA_PROTO2(a,b)                                          void *__tp_data,a b
  94 #define _TP_EXDATA_PROTO4(a,b,c,d)                                      void *__tp_data,a b,c d
  95 #define _TP_EXDATA_PROTO6(a,b,c,d,e,f)                                  void *__tp_data,a b,c d,e f
  96 #define _TP_EXDATA_PROTO8(a,b,c,d,e,f,g,h)                              void *__tp_data,a b,c d,e f,g h
  97 #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
  98 #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
  99 #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
 100 #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
 101 #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
 102 #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
 103
 104 /* Preprocessor trick to count arguments. Inspired from sdt.h. */
 105 #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)
 106 #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
 107 #define _TP_PROTO_N(N, ...)             _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXPROTO, N)(__VA_ARGS__))
 108 #define _TP_VAR_N(N, ...)               _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXVAR, N)(__VA_ARGS__))
 109 #define _TP_DATA_PROTO_N(N, ...)        _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXDATA_PROTO, N)(__VA_ARGS__))
 110 #define _TP_DATA_VAR_N(N, ...)          _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXDATA_VAR, N)(__VA_ARGS__))
 111 #define _TP_ARGS_PROTO(...)             _TP_PROTO_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 112 #define _TP_ARGS_VAR(...)               _TP_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 113 #define _TP_ARGS_DATA_PROTO(...)        _TP_DATA_PROTO_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 114 #define _TP_ARGS_DATA_VAR(...)          _TP_DATA_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 115 #define _TP_PARAMS(...)                 __VA_ARGS__
 116
 117 #define _DECLARE_TRACEPOINT(provider, name, ...)                                        \
 118 extern struct tracepoint __tracepoint_##provider##___##name;                            \
 119 static inline void __tracepoint_cb_##provider##___##name(_TP_ARGS_PROTO(__VA_ARGS__))   \
 120 {                                                                                       \
 121         struct tracepoint_probe *__tp_probe;                                            \
 122                                                                                         \
 123         if (!TP_RCU_LINK_TEST())                                                        \
 124                 return;                                                                 \
 125         tp_rcu_read_lock_bp();                                                          \
 126         __tp_probe = tp_rcu_dereference_bp(__tracepoint_##provider##___##name.probes);  \
 127         if (caa_unlikely(!__tp_probe))                                                  \
 128                 goto end;                                                               \
 129         do {                                                                            \
 130                 void *__tp_cb = __tp_probe->func;                                       \
 131                 void *__tp_data = __tp_probe->data;                                     \
 132                                                                                         \
 133                 URCU_FORCE_CAST(void (*)(_TP_ARGS_DATA_PROTO(__VA_ARGS__)), __tp_cb)    \
 134                                 (_TP_ARGS_DATA_VAR(__VA_ARGS__));                       \
 135         } while ((++__tp_probe)->func);                                                 \
 136 end:                                                                                    \
 137         tp_rcu_read_unlock_bp();                                                        \
 138 }                                                                                       \
 139 static inline void __tracepoint_register_##provider##___##name(char *name,              \
 140                 void *func, void *data)                                                 \
 141 {                                                                                       \
 142         __tracepoint_probe_register(name, func, data);                                  \
 143 }                                                                                       \
 144 static inline void __tracepoint_unregister_##provider##___##name(char *name,            \
 145                 void *func, void *data)                                                 \
 146 {                                                                                       \
 147         __tracepoint_probe_unregister(name, func, data);                                \
 148 }
 149
 150 extern int __tracepoint_probe_register(const char *name, void *func, void *data);
 151 extern int __tracepoint_probe_unregister(const char *name, void *func, void *data);
 152
 153 #ifdef TRACEPOINT_DEFINE
 154
 155 /*
 156  * Note: to allow PIC code, we need to allow the linker to update the pointers
 157  * in the __tracepoints_ptrs section.
 158  * Therefore, this section is _not_ const (read-only).
 159  */
 160 #define _DEFINE_TRACEPOINT(provider, name)                                      \
 161         static const char __tp_strtab_##provider##___##name[]                   \
 162                 __attribute__((section("__tracepoints_strings"))) =             \
 163                         #provider ":" #name;                                    \
 164         struct tracepoint __tracepoint_##provider##___##name                    \
 165                 __attribute__((section("__tracepoints"))) =                     \
 166                         { __tp_strtab_##provider##___##name, 0, NULL };         \
 167         static struct tracepoint * __tracepoint_ptr_##provider##___##name       \
 168                 __attribute__((used, section("__tracepoints_ptrs"))) =          \
 169                         &__tracepoint_##provider##___##name;
 170
 171 static int (*tracepoint_register_lib)(struct tracepoint * const *tracepoints_start,
 172                 int tracepoints_count);
 173 static int (*tracepoint_unregister_lib)(struct tracepoint * const *tracepoints_start);
 174 static void *liblttngust_handle;
 175
 176 /*
 177  * These weak symbols, the constructor, and destructor take care of
 178  * registering only _one_ instance of the tracepoints per shared-ojbect
 179  * (or for the whole main program).
 180  */
 181 extern struct tracepoint * const __start___tracepoints_ptrs[]
 182         __attribute__((weak, visibility("hidden")));
 183 extern struct tracepoint * const __stop___tracepoints_ptrs[]
 184         __attribute__((weak, visibility("hidden")));
 185 int __tracepoint_registered
 186         __attribute__((weak, visibility("hidden")));
 187
 188 static void __attribute__((constructor)) __tracepoints__init(void)
 189 {
 190         if (__tracepoint_registered++)
 191                 return;
 192
 193         liblttngust_handle = dlopen("liblttng-ust.so", RTLD_NOW | RTLD_GLOBAL);
 194         if (!liblttngust_handle)
 195                 return;
 196         tracepoint_register_lib =
 197                 URCU_FORCE_CAST(int (*)(struct tracepoint * const *, int),
 198                                 dlsym(liblttngust_handle,
 199                                         "tracepoint_register_lib"));
 200         tracepoint_unregister_lib =
 201                 URCU_FORCE_CAST(int (*)(struct tracepoint * const *),
 202                                 dlsym(liblttngust_handle,
 203                                         "tracepoint_unregister_lib"));
 204 #ifndef _LGPL_SOURCE
 205         tp_rcu_read_lock_bp =
 206                 URCU_FORCE_CAST(void (*)(void),
 207                                 dlsym(liblttngust_handle,
 208                                         "tp_rcu_read_lock_bp"));
 209         tp_rcu_read_unlock_bp =
 210                 URCU_FORCE_CAST(void (*)(void),
 211                                 dlsym(liblttngust_handle,
 212                                         "tp_rcu_read_unlock_bp"));
 213         tp_rcu_dereference_sym_bp =
 214                 URCU_FORCE_CAST(void *(*)(void *p),
 215                                 dlsym(liblttngust_handle,
 216                                         "tp_rcu_dereference_sym_bp"));
 217 #endif
 218         tracepoint_register_lib(__start___tracepoints_ptrs,
 219                                 __stop___tracepoints_ptrs -
 220                                 __start___tracepoints_ptrs);
 221 }
 222
 223 static void __attribute__((destructor)) __tracepoints__destroy(void)
 224 {
 225         int ret;
 226         if (--__tracepoint_registered)
 227                 return;
 228         if (tracepoint_unregister_lib)
 229                 tracepoint_unregister_lib(__start___tracepoints_ptrs);
 230         if (liblttngust_handle) {
 231                 tracepoint_unregister_lib = NULL;
 232                 tracepoint_register_lib = NULL;
 233                 ret = dlclose(liblttngust_handle);
 234                 assert(!ret);
 235         }
 236 }
 237
 238 #else /* TRACEPOINT_DEFINE */
 239
 240 #define _DEFINE_TRACEPOINT(provider, name)
 241
 242 #endif /* #else TRACEPOINT_DEFINE */
 243
 244 #ifdef __cplusplus
 245 }
 246 #endif
 247
 248 #endif /* _LTTNG_TRACEPOINT_H */
 249
 250 /* The following declarations must be outside re-inclusion protection. */
 251
 252 #ifndef TRACEPOINT_EVENT
 253
 254 /*
 255  * How to use the TRACEPOINT_EVENT macro:
 256  *
 257  * An example:
 258  *
 259  * TRACEPOINT_EVENT(someproject_component, event_name,
 260  *
 261  *     * TP_ARGS takes from 0 to 10 "type, field_name" pairs *
 262  *
 263  *     TP_ARGS(int, arg0, void *, arg1, char *, string, size_t, strlen,
 264  *             long *, arg4, size_t, arg4_len),
 265  *
 266  *      * TP_FIELDS describes the event payload layout in the trace *
 267  *
 268  *     TP_FIELDS(
 269  *         * Integer, printed in base 10 *
 270  *         ctf_integer(int, field_a, arg0)
 271  *
 272  *         * Integer, printed with 0x base 16 *
 273  *         ctf_integer_hex(unsigned long, field_d, arg1)
 274  *
 275  *         * Array Sequence, printed as UTF8-encoded array of bytes *
 276  *         ctf_array_text(char, field_b, string, FIXED_LEN)
 277  *         ctf_sequence_text(char, field_c, string, size_t, strlen)
 278  *
 279  *         * String, printed as UTF8-encoded string *
 280  *         ctf_string(field_e, string)
 281  *
 282  *         * Array sequence of signed integer values *
 283  *         ctf_array(long, field_f, arg4, FIXED_LEN4)
 284  *         ctf_sequence(long, field_g, arg4, size_t, arg4_len)
 285  *     )
 286  * )
 287  *
 288  * More detailed explanation:
 289  *
 290  * The name of the tracepoint is expressed as a tuple with the provider
 291  * and name arguments.
 292  *
 293  * The provider and name should be a proper C99 identifier.
 294  * The "provider" and "name" MUST follow these rules to ensure no
 295  * namespace clash occurs:
 296  *
 297  * For projects (applications and libraries) for which an entity
 298  * specific to the project controls the source code and thus its
 299  * tracepoints (typically with a scope larger than a single company):
 300  *
 301  * either:
 302  *   project_component, event
 303  * or:
 304  *   project, event
 305  *
 306  * Where "project" is the name of the project,
 307  *       "component" is the name of the project component (which may
 308  *       include several levels of sub-components, e.g.
 309  *       ...component_subcomponent_...) where the tracepoint is located
 310  *       (optional),
 311  *       "event" is the name of the tracepoint event.
 312  *
 313  * For projects issued from a single company wishing to advertise that
 314  * the company controls the source code and thus the tracepoints, the
 315  * "com_" prefix should be used:
 316  *
 317  * either:
 318  *   com_company_project_component, event
 319  * or:
 320  *   com_company_project, event
 321  *
 322  * Where "company" is the name of the company,
 323  *       "project" is the name of the project,
 324  *       "component" is the name of the project component (which may
 325  *       include several levels of sub-components, e.g.
 326  *       ...component_subcomponent_...) where the tracepoint is located
 327  *       (optional),
 328  *       "event" is the name of the tracepoint event.
 329  *
 330  * the provider:event identifier is limited to 127 characters.
 331  */
 332
 333 #define TRACEPOINT_EVENT(provider, name, args, fields)                  \
 334         _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))           \
 335         _DEFINE_TRACEPOINT(provider, name)
 336
 337 #define TRACEPOINT_EVENT_CLASS(provider, name, args, fields)
 338
 339 #define TRACEPOINT_EVENT_INSTANCE(provider, _template, name, args)      \
 340         _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))           \
 341         _DEFINE_TRACEPOINT(provider, name)
 342
 343 #endif /* #ifndef TRACEPOINT_EVENT */
 344
 345 #ifndef TRACEPOINT_LOGLEVEL
 346
 347 /*
 348  * Tracepoint Loglevel Declaration Facility
 349  *
 350  * This is a place-holder the tracepoint loglevel declaration,
 351  * overridden by the tracer implementation.
 352  *
 353  * Typical use of these loglevels:
 354  *
 355  * 1) Declare the mapping between loglevel names and an integer values
 356  *    within TRACEPOINT_LOGLEVEL_ENUM(), using tp_loglevel() for each
 357  *    tuple. Do _NOT_ add comma (,) nor semicolon (;) between the
 358  *    tp_loglevel entries contained within TRACEPOINT_LOGLEVEL_ENUM().
 359  *    Do _NOT_ add comma (,) nor semicolon (;) after the
 360  *    TRACEPOINT_LOGLEVEL_ENUM() declaration.  The name should be a
 361  *    proper C99 identifier.
 362  *
 363  *      TRACEPOINT_LOGLEVEL_ENUM(
 364  *              tp_loglevel( < loglevel_name >, < value > )
 365  *              tp_loglevel( < loglevel_name >, < value > )
 366  *              ...
 367  *      )
 368  *
 369  *    e.g.:
 370  *
 371  *      TRACEPOINT_LOGLEVEL_ENUM(
 372  *              tp_loglevel(LOG_EMERG,   0)
 373  *              tp_loglevel(LOG_ALERT,   1)
 374  *              tp_loglevel(LOG_CRIT,    2)
 375  *              tp_loglevel(LOG_ERR,     3)
 376  *              tp_loglevel(LOG_WARNING, 4)
 377  *              tp_loglevel(LOG_NOTICE,  5)
 378  *              tp_loglevel(LOG_INFO,    6)
 379  *              tp_loglevel(LOG_DEBUG,   7)
 380  *      )
 381  *
 382  * 2) Then, declare tracepoint loglevels for tracepoints. A
 383  *    TRACEPOINT_EVENT should be declared prior to the the
 384  *    TRACEPOINT_LOGLEVEL for a given tracepoint name. The first field
 385  *    is the name of the tracepoint, the second field is the loglevel
 386  *    name.
 387  *
 388  *      TRACEPOINT_LOGLEVEL(< [com_company_]project[_component] >, < event >,
 389  *              < loglevel_name >)
 390  *
 391  * The TRACEPOINT_PROVIDER must be defined when declaring a
 392  * TRACEPOINT_LOGLEVEL_ENUM and TRACEPOINT_LOGLEVEL. The tracepoint
 393  * loglevel enumeration apply to the entire TRACEPOINT_PROVIDER. Only one
 394  * tracepoint loglevel enumeration should be declared per tracepoint
 395  * provider.
 396  */
 397
 398 #define TRACEPOINT_LOGLEVEL_ENUM(...)
 399 #define TRACEPOINT_LOGLEVEL(provider, name, loglevel)
 400
 401 #endif /* #ifndef TRACEPOINT_LOGLEVEL */