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 #include <dlfcn.h>      /* for dlopen */
  21
  22 #ifdef __cplusplus
  23 extern "C" {
  24 #endif
  25
  26 #define tracepoint(provider, name, ...)                                     \
  27         do {                                                                \
  28                 if (caa_unlikely(__tracepoint_##provider##___##name.state)) \
  29                         __tracepoint_cb_##provider##___##name(__VA_ARGS__); \
  30         } while (0)
  31
  32 #define TP_ARGS(...)       __VA_ARGS__
  33
  34 /*
  35  * TP_ARGS takes tuples of type, argument separated by a comma.
  36  * It can take up to 10 tuples (which means that less than 10 tuples is
  37  * fine too).
  38  * Each tuple is also separated by a comma.
  39  */
  40 #define _TP_COMBINE_TOKENS1(_tokena, _tokenb)       _tokena##_tokenb
  41 #define _TP_COMBINE_TOKENS(_tokena, _tokenb)        _TP_COMBINE_TOKENS1(_tokena, _tokenb)
  42
  43 /* _TP_EXVAR* extract the var names. */
  44 #define _TP_EXVAR0()
  45 #define _TP_EXVAR2(a,b)                                         b
  46 #define _TP_EXVAR4(a,b,c,d)                                     b,d
  47 #define _TP_EXVAR6(a,b,c,d,e,f)                                 b,d,f
  48 #define _TP_EXVAR8(a,b,c,d,e,f,g,h)                             b,d,f,h
  49 #define _TP_EXVAR10(a,b,c,d,e,f,g,h,i,j)                        b,d,f,h,j
  50 #define _TP_EXVAR12(a,b,c,d,e,f,g,h,i,j,k,l)                    b,d,f,h,j,l
  51 #define _TP_EXVAR14(a,b,c,d,e,f,g,h,i,j,k,l,m,n)                b,d,f,h,j,l,n
  52 #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
  53 #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
  54 #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
  55
  56 #define _TP_EXDATA_VAR0()                                               __tp_data
  57 #define _TP_EXDATA_VAR2(a,b)                                            __tp_data,b
  58 #define _TP_EXDATA_VAR4(a,b,c,d)                                        __tp_data,b,d
  59 #define _TP_EXDATA_VAR6(a,b,c,d,e,f)                                    __tp_data,b,d,f
  60 #define _TP_EXDATA_VAR8(a,b,c,d,e,f,g,h)                                __tp_data,b,d,f,h
  61 #define _TP_EXDATA_VAR10(a,b,c,d,e,f,g,h,i,j)                           __tp_data,b,d,f,h,j
  62 #define _TP_EXDATA_VAR12(a,b,c,d,e,f,g,h,i,j,k,l)                       __tp_data,b,d,f,h,j,l
  63 #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
  64 #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
  65 #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
  66 #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
  67
  68 /* _TP_EXPROTO* extract tuples of type, var */
  69 #define _TP_EXPROTO0()
  70 #define _TP_EXPROTO2(a,b)                                       a b
  71 #define _TP_EXPROTO4(a,b,c,d)                                   a b,c d
  72 #define _TP_EXPROTO6(a,b,c,d,e,f)                               a b,c d,e f
  73 #define _TP_EXPROTO8(a,b,c,d,e,f,g,h)                           a b,c d,e f,g h
  74 #define _TP_EXPROTO10(a,b,c,d,e,f,g,h,i,j)                      a b,c d,e f,g h,i j
  75 #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
  76 #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
  77 #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
  78 #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
  79 #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
  80
  81 #define _TP_EXDATA_PROTO0()                                             void *__tp_data
  82 #define _TP_EXDATA_PROTO2(a,b)                                          void *__tp_data,a b
  83 #define _TP_EXDATA_PROTO4(a,b,c,d)                                      void *__tp_data,a b,c d
  84 #define _TP_EXDATA_PROTO6(a,b,c,d,e,f)                                  void *__tp_data,a b,c d,e f
  85 #define _TP_EXDATA_PROTO8(a,b,c,d,e,f,g,h)                              void *__tp_data,a b,c d,e f,g h
  86 #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
  87 #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
  88 #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
  89 #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
  90 #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
  91 #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
  92
  93 /* Preprocessor trick to count arguments. Inspired from sdt.h. */
  94 #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)
  95 #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
  96 #define _TP_PROTO_N(N, ...)             _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXPROTO, N)(__VA_ARGS__))
  97 #define _TP_VAR_N(N, ...)               _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXVAR, N)(__VA_ARGS__))
  98 #define _TP_DATA_PROTO_N(N, ...)        _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXDATA_PROTO, N)(__VA_ARGS__))
  99 #define _TP_DATA_VAR_N(N, ...)          _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXDATA_VAR, N)(__VA_ARGS__))
 100 #define _TP_ARGS_PROTO(...)             _TP_PROTO_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 101 #define _TP_ARGS_VAR(...)               _TP_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 102 #define _TP_ARGS_DATA_PROTO(...)        _TP_DATA_PROTO_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 103 #define _TP_ARGS_DATA_VAR(...)          _TP_DATA_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 104 #define _TP_PARAMS(...)                 __VA_ARGS__
 105
 106 #define _DECLARE_TRACEPOINT(provider, name, ...)                                        \
 107 extern struct tracepoint __tracepoint_##provider##___##name;                            \
 108 static inline void __tracepoint_cb_##provider##___##name(_TP_ARGS_PROTO(__VA_ARGS__))   \
 109 {                                                                                       \
 110         struct tracepoint_probe *__tp_probe;                                            \
 111                                                                                         \
 112         if (!rcu_read_lock_bp)                                                          \
 113                 return;                                                                 \
 114         rcu_read_lock_bp();                                                             \
 115         __tp_probe = rcu_dereference_bp(__tracepoint_##provider##___##name.probes);     \
 116         if (caa_unlikely(!__tp_probe))                                                  \
 117                 goto end;                                                               \
 118         do {                                                                            \
 119                 void *__tp_cb = __tp_probe->func;                                       \
 120                 void *__tp_data = __tp_probe->data;                                     \
 121                                                                                         \
 122                 URCU_FORCE_CAST(void (*)(_TP_ARGS_DATA_PROTO(__VA_ARGS__)), __tp_cb)    \
 123                                 (_TP_ARGS_DATA_VAR(__VA_ARGS__));                       \
 124         } while ((++__tp_probe)->func);                                                 \
 125 end:                                                                                    \
 126         rcu_read_unlock_bp();                                                           \
 127 }                                                                                       \
 128 static inline void __tracepoint_register_##provider##___##name(char *name,              \
 129                 void *func, void *data)                                                 \
 130 {                                                                                       \
 131         __tracepoint_probe_register(name, func, data);                                  \
 132 }                                                                                       \
 133 static inline void __tracepoint_unregister_##provider##___##name(char *name,            \
 134                 void *func, void *data)                                                 \
 135 {                                                                                       \
 136         __tracepoint_probe_unregister(name, func, data);                                \
 137 }
 138
 139 extern int __tracepoint_probe_register(const char *name, void *func, void *data);
 140 extern int __tracepoint_probe_unregister(const char *name, void *func, void *data);
 141
 142 #ifdef TRACEPOINT_DEFINE
 143
 144 /*
 145  * Note: to allow PIC code, we need to allow the linker to update the pointers
 146  * in the __tracepoints_ptrs section.
 147  * Therefore, this section is _not_ const (read-only).
 148  */
 149 #define _DEFINE_TRACEPOINT(provider, name)                                      \
 150         static const char __tp_strtab_##provider##___##name[]                   \
 151                 __attribute__((section("__tracepoints_strings"))) =             \
 152                         #provider ":" #name;                                    \
 153         struct tracepoint __tracepoint_##provider##___##name                    \
 154                 __attribute__((section("__tracepoints"))) =                     \
 155                         { __tp_strtab_##provider##___##name, 0, NULL };         \
 156         static struct tracepoint * __tracepoint_ptr_##provider##___##name       \
 157                 __attribute__((used, section("__tracepoints_ptrs"))) =          \
 158                         &__tracepoint_##provider##___##name;
 159
 160 static int (*tracepoint_register_lib)(struct tracepoint * const *tracepoints_start,
 161                 int tracepoints_count);
 162 static int (*tracepoint_unregister_lib)(struct tracepoint * const *tracepoints_start);
 163 static void *liblttngust_handle;
 164
 165 /*
 166  * These weak symbols, the constructor, and destructor take care of
 167  * registering only _one_ instance of the tracepoints per shared-ojbect
 168  * (or for the whole main program).
 169  */
 170 extern struct tracepoint * const __start___tracepoints_ptrs[]
 171         __attribute__((weak, visibility("hidden")));
 172 extern struct tracepoint * const __stop___tracepoints_ptrs[]
 173         __attribute__((weak, visibility("hidden")));
 174 int __tracepoint_registered
 175         __attribute__((weak, visibility("hidden")));
 176
 177 static void __attribute__((constructor)) __tracepoints__init(void)
 178 {
 179         if (__tracepoint_registered++)
 180                 return;
 181
 182         liblttngust_handle = dlopen("liblttng-ust.so", RTLD_NOW | RTLD_GLOBAL);
 183         if (!liblttngust_handle)
 184                 return;
 185         tracepoint_register_lib =
 186                 URCU_FORCE_CAST(int (*)(struct tracepoint * const *, int),
 187                                 dlsym(liblttngust_handle,
 188                                         "tracepoint_register_lib"));
 189         tracepoint_unregister_lib =
 190                 URCU_FORCE_CAST(int (*)(struct tracepoint * const *),
 191                                 dlsym(liblttngust_handle,
 192                                         "tracepoint_unregister_lib"));
 193         tracepoint_register_lib(__start___tracepoints_ptrs,
 194                                 __stop___tracepoints_ptrs -
 195                                 __start___tracepoints_ptrs);
 196 }
 197
 198 static void __attribute__((destructor)) __tracepoints__destroy(void)
 199 {
 200         int ret;
 201         if (--__tracepoint_registered)
 202                 return;
 203         if (tracepoint_unregister_lib)
 204                 tracepoint_unregister_lib(__start___tracepoints_ptrs);
 205         if (liblttngust_handle) {
 206                 tracepoint_unregister_lib = NULL;
 207                 tracepoint_register_lib = NULL;
 208                 ret = dlclose(liblttngust_handle);
 209                 assert(!ret);
 210         }
 211 }
 212
 213 #else /* TRACEPOINT_DEFINE */
 214
 215 #define _DEFINE_TRACEPOINT(provider, name)
 216
 217 #endif /* #else TRACEPOINT_DEFINE */
 218
 219 #ifdef __cplusplus
 220 }
 221 #endif
 222
 223 #endif /* _LTTNG_TRACEPOINT_H */
 224
 225 /* The following declarations must be outside re-inclusion protection. */
 226
 227 #ifndef TRACEPOINT_EVENT
 228
 229 /*
 230  * How to use the TRACEPOINT_EVENT macro:
 231  *
 232  * An example:
 233  *
 234  * TRACEPOINT_EVENT(someproject_component, event_name,
 235  *
 236  *     * TP_ARGS takes from 0 to 10 "type, field_name" pairs *
 237  *
 238  *     TP_ARGS(int, arg0, void *, arg1, char *, string, size_t, strlen,
 239  *             long *, arg4, size_t, arg4_len),
 240  *
 241  *      * TP_FIELDS describes the event payload layout in the trace *
 242  *
 243  *     TP_FIELDS(
 244  *         * Integer, printed in base 10 *
 245  *         ctf_integer(int, field_a, arg0)
 246  *
 247  *         * Integer, printed with 0x base 16 *
 248  *         ctf_integer_hex(unsigned long, field_d, arg1)
 249  *
 250  *         * Array Sequence, printed as UTF8-encoded array of bytes *
 251  *         ctf_array_text(char, field_b, string, FIXED_LEN)
 252  *         ctf_sequence_text(char, field_c, string, size_t, strlen)
 253  *
 254  *         * String, printed as UTF8-encoded string *
 255  *         ctf_string(field_e, string)
 256  *
 257  *         * Array sequence of signed integer values *
 258  *         ctf_array(long, field_f, arg4, FIXED_LEN4)
 259  *         ctf_sequence(long, field_g, arg4, size_t, arg4_len)
 260  *     )
 261  * )
 262  *
 263  * More detailed explanation:
 264  *
 265  * The name of the tracepoint is expressed as a tuple with the provider
 266  * and name arguments.
 267  *
 268  * The provider and name should be a proper C99 identifier.
 269  * The "provider" and "name" MUST follow these rules to ensure no
 270  * namespace clash occurs:
 271  *
 272  * For projects (applications and libraries) for which an entity
 273  * specific to the project controls the source code and thus its
 274  * tracepoints (typically with a scope larger than a single company):
 275  *
 276  * either:
 277  *   project_component, event
 278  * or:
 279  *   project, event
 280  *
 281  * Where "project" is the name of the project,
 282  *       "component" is the name of the project component (which may
 283  *       include several levels of sub-components, e.g.
 284  *       ...component_subcomponent_...) where the tracepoint is located
 285  *       (optional),
 286  *       "event" is the name of the tracepoint event.
 287  *
 288  * For projects issued from a single company wishing to advertise that
 289  * the company controls the source code and thus the tracepoints, the
 290  * "com_" prefix should be used:
 291  *
 292  * either:
 293  *   com_company_project_component, event
 294  * or:
 295  *   com_company_project, event
 296  *
 297  * Where "company" is the name of the company,
 298  *       "project" is the name of the project,
 299  *       "component" is the name of the project component (which may
 300  *       include several levels of sub-components, e.g.
 301  *       ...component_subcomponent_...) where the tracepoint is located
 302  *       (optional),
 303  *       "event" is the name of the tracepoint event.
 304  *
 305  * the provider:event identifier is limited to 127 characters.
 306  */
 307
 308 #define TRACEPOINT_EVENT(provider, name, args, fields)                  \
 309         _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))           \
 310         _DEFINE_TRACEPOINT(provider, name)
 311
 312 #define TRACEPOINT_EVENT_CLASS(provider, name, args, fields)
 313
 314 #define TRACEPOINT_EVENT_INSTANCE(provider, _template, name, args)      \
 315         _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))           \
 316         _DEFINE_TRACEPOINT(provider, name)
 317
 318 #endif /* #ifndef TRACEPOINT_EVENT */
 319
 320 #ifndef TRACEPOINT_LOGLEVEL
 321
 322 /*
 323  * Tracepoint Loglevel Declaration Facility
 324  *
 325  * This is a place-holder the tracepoint loglevel declaration,
 326  * overridden by the tracer implementation.
 327  *
 328  * Typical use of these loglevels:
 329  *
 330  * 1) Declare the mapping between loglevel names and an integer values
 331  *    within TRACEPOINT_LOGLEVEL_ENUM(), using tp_loglevel() for each
 332  *    tuple. Do _NOT_ add comma (,) nor semicolon (;) between the
 333  *    tp_loglevel entries contained within TRACEPOINT_LOGLEVEL_ENUM().
 334  *    Do _NOT_ add comma (,) nor semicolon (;) after the
 335  *    TRACEPOINT_LOGLEVEL_ENUM() declaration.  The name should be a
 336  *    proper C99 identifier.
 337  *
 338  *      TRACEPOINT_LOGLEVEL_ENUM(
 339  *              tp_loglevel( < loglevel_name >, < value > )
 340  *              tp_loglevel( < loglevel_name >, < value > )
 341  *              ...
 342  *      )
 343  *
 344  *    e.g.:
 345  *
 346  *      TRACEPOINT_LOGLEVEL_ENUM(
 347  *              tp_loglevel(LOG_EMERG,   0)
 348  *              tp_loglevel(LOG_ALERT,   1)
 349  *              tp_loglevel(LOG_CRIT,    2)
 350  *              tp_loglevel(LOG_ERR,     3)
 351  *              tp_loglevel(LOG_WARNING, 4)
 352  *              tp_loglevel(LOG_NOTICE,  5)
 353  *              tp_loglevel(LOG_INFO,    6)
 354  *              tp_loglevel(LOG_DEBUG,   7)
 355  *      )
 356  *
 357  * 2) Then, declare tracepoint loglevels for tracepoints. A
 358  *    TRACEPOINT_EVENT should be declared prior to the the
 359  *    TRACEPOINT_LOGLEVEL for a given tracepoint name. The first field
 360  *    is the name of the tracepoint, the second field is the loglevel
 361  *    name.
 362  *
 363  *      TRACEPOINT_LOGLEVEL(< [com_company_]project[_component] >, < event >,
 364  *              < loglevel_name >)
 365  *
 366  * The TRACEPOINT_PROVIDER must be defined when declaring a
 367  * TRACEPOINT_LOGLEVEL_ENUM and TRACEPOINT_LOGLEVEL. The tracepoint
 368  * loglevel enumeration apply to the entire TRACEPOINT_PROVIDER. Only one
 369  * tracepoint loglevel enumeration should be declared per tracepoint
 370  * provider.
 371  */
 372
 373 #define TRACEPOINT_LOGLEVEL_ENUM(...)
 374 #define TRACEPOINT_LOGLEVEL(provider, name, loglevel)
 375
 376 #endif /* #ifndef TRACEPOINT_LOGLEVEL */