include/lttng/tracepoint.h

   1 #ifndef _LTTNG_TRACEPOINT_H
   2 #define _LTTNG_TRACEPOINT_H
   3
   4 /*
   5  * Copyright 2011-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23  * SOFTWARE.
  24  */
  25
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <lttng/tracepoint-types.h>
  29 #include <lttng/tracepoint-rcu.h>
  30 #include <urcu/compiler.h>
  31 #include <urcu/system.h>
  32 #include <dlfcn.h>      /* for dlopen */
  33 #include <string.h>     /* for memset */
  34 #include <lttng/ust-config.h>   /* for sdt */
  35 #include <lttng/ust-compiler.h>
  36
  37 #ifdef LTTNG_UST_HAVE_SDT_INTEGRATION
  38 /*
  39  * Instead of using SDT_USE_VARIADIC from 'sys/sdt.h', use our own namespaced
  40  * macros since the instrumented application might already have included
  41  * 'sys/sdt.h' without variadic support.
  42  */
  43 #include <sys/sdt.h>
  44
  45 #define _LTTNG_SDT_NARG(...) \
  46         __LTTNG_SDT_NARG(__VA_ARGS__, 12,11,10,9,8,7,6,5,4,3,2,1,0)
  47
  48 #define __LTTNG_SDT_NARG(_0,_1,_2,_3,_4,_5,_6,_7,_8,_9,_10,_11,_12, N, ...) N
  49
  50 #define _LTTNG_SDT_PROBE_N(provider, name, N, ...) \
  51         _SDT_PROBE(provider, name, N, (__VA_ARGS__))
  52
  53 #define LTTNG_STAP_PROBEV(provider, name, ...) \
  54         _LTTNG_SDT_PROBE_N(provider, name, _LTTNG_SDT_NARG(0, ##__VA_ARGS__), ##__VA_ARGS__)
  55
  56 #else
  57 #define LTTNG_STAP_PROBEV(...)
  58 #endif
  59
  60 #ifdef __cplusplus
  61 extern "C" {
  62 #endif
  63
  64 #define tracepoint_enabled(provider, name) \
  65         caa_unlikely(CMM_LOAD_SHARED(__tracepoint_##provider##___##name.state))
  66
  67 #define do_tracepoint(provider, name, ...) \
  68         __tracepoint_cb_##provider##___##name(__VA_ARGS__)
  69
  70 #define tracepoint(provider, name, ...)                                     \
  71         do {                                                                \
  72                 LTTNG_STAP_PROBEV(provider, name, ## __VA_ARGS__);          \
  73                 if (tracepoint_enabled(provider, name))                     \
  74                         do_tracepoint(provider, name, __VA_ARGS__);         \
  75         } while (0)
  76
  77 #define TP_ARGS(...)       __VA_ARGS__
  78
  79 /*
  80  * TP_ARGS takes tuples of type, argument separated by a comma.
  81  * It can take up to 10 tuples (which means that less than 10 tuples is
  82  * fine too).
  83  * Each tuple is also separated by a comma.
  84  */
  85 #define __TP_COMBINE_TOKENS(_tokena, _tokenb)                           \
  86                 _tokena##_tokenb
  87 #define _TP_COMBINE_TOKENS(_tokena, _tokenb)                            \
  88                 __TP_COMBINE_TOKENS(_tokena, _tokenb)
  89 #define __TP_COMBINE_TOKENS3(_tokena, _tokenb, _tokenc)                 \
  90                 _tokena##_tokenb##_tokenc
  91 #define _TP_COMBINE_TOKENS3(_tokena, _tokenb, _tokenc)                  \
  92                 __TP_COMBINE_TOKENS3(_tokena, _tokenb, _tokenc)
  93 #define __TP_COMBINE_TOKENS4(_tokena, _tokenb, _tokenc, _tokend)        \
  94                 _tokena##_tokenb##_tokenc##_tokend
  95 #define _TP_COMBINE_TOKENS4(_tokena, _tokenb, _tokenc, _tokend)         \
  96                 __TP_COMBINE_TOKENS4(_tokena, _tokenb, _tokenc, _tokend)
  97
  98 /*
  99  * _TP_EXVAR* extract the var names.
 100  * _TP_EXVAR1 and _TP_EXDATA_VAR1 are needed for -std=c99.
 101  */
 102 #define _TP_EXVAR0()
 103 #define _TP_EXVAR1(a)
 104 #define _TP_EXVAR2(a,b)                                         b
 105 #define _TP_EXVAR4(a,b,c,d)                                     b,d
 106 #define _TP_EXVAR6(a,b,c,d,e,f)                                 b,d,f
 107 #define _TP_EXVAR8(a,b,c,d,e,f,g,h)                             b,d,f,h
 108 #define _TP_EXVAR10(a,b,c,d,e,f,g,h,i,j)                        b,d,f,h,j
 109 #define _TP_EXVAR12(a,b,c,d,e,f,g,h,i,j,k,l)                    b,d,f,h,j,l
 110 #define _TP_EXVAR14(a,b,c,d,e,f,g,h,i,j,k,l,m,n)                b,d,f,h,j,l,n
 111 #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
 112 #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
 113 #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
 114
 115 #define _TP_EXDATA_VAR0()                                               __tp_data
 116 #define _TP_EXDATA_VAR1(a)                                              __tp_data
 117 #define _TP_EXDATA_VAR2(a,b)                                            __tp_data,b
 118 #define _TP_EXDATA_VAR4(a,b,c,d)                                        __tp_data,b,d
 119 #define _TP_EXDATA_VAR6(a,b,c,d,e,f)                                    __tp_data,b,d,f
 120 #define _TP_EXDATA_VAR8(a,b,c,d,e,f,g,h)                                __tp_data,b,d,f,h
 121 #define _TP_EXDATA_VAR10(a,b,c,d,e,f,g,h,i,j)                           __tp_data,b,d,f,h,j
 122 #define _TP_EXDATA_VAR12(a,b,c,d,e,f,g,h,i,j,k,l)                       __tp_data,b,d,f,h,j,l
 123 #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
 124 #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
 125 #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
 126 #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
 127
 128 /*
 129  * _TP_EXPROTO* extract tuples of type, var.
 130  * _TP_EXPROTO1 and _TP_EXDATA_PROTO1 are needed for -std=c99.
 131  */
 132 #define _TP_EXPROTO0()                                          void
 133 #define _TP_EXPROTO1(a)                                         void
 134 #define _TP_EXPROTO2(a,b)                                       a b
 135 #define _TP_EXPROTO4(a,b,c,d)                                   a b,c d
 136 #define _TP_EXPROTO6(a,b,c,d,e,f)                               a b,c d,e f
 137 #define _TP_EXPROTO8(a,b,c,d,e,f,g,h)                           a b,c d,e f,g h
 138 #define _TP_EXPROTO10(a,b,c,d,e,f,g,h,i,j)                      a b,c d,e f,g h,i j
 139 #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
 140 #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
 141 #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
 142 #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
 143 #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
 144
 145 #define _TP_EXDATA_PROTO0()                                             void *__tp_data
 146 #define _TP_EXDATA_PROTO1(a)                                            void *__tp_data
 147 #define _TP_EXDATA_PROTO2(a,b)                                          void *__tp_data,a b
 148 #define _TP_EXDATA_PROTO4(a,b,c,d)                                      void *__tp_data,a b,c d
 149 #define _TP_EXDATA_PROTO6(a,b,c,d,e,f)                                  void *__tp_data,a b,c d,e f
 150 #define _TP_EXDATA_PROTO8(a,b,c,d,e,f,g,h)                              void *__tp_data,a b,c d,e f,g h
 151 #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
 152 #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
 153 #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
 154 #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
 155 #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
 156 #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
 157
 158 /* Preprocessor trick to count arguments. Inspired from sdt.h. */
 159 #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)
 160 #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
 161 #define _TP_PROTO_N(N, ...)             _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXPROTO, N)(__VA_ARGS__))
 162 #define _TP_VAR_N(N, ...)               _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXVAR, N)(__VA_ARGS__))
 163 #define _TP_DATA_PROTO_N(N, ...)        _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXDATA_PROTO, N)(__VA_ARGS__))
 164 #define _TP_DATA_VAR_N(N, ...)          _TP_PARAMS(_TP_COMBINE_TOKENS(_TP_EXDATA_VAR, N)(__VA_ARGS__))
 165 #define _TP_ARGS_PROTO(...)             _TP_PROTO_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 166 #define _TP_ARGS_VAR(...)               _TP_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 167 #define _TP_ARGS_DATA_PROTO(...)        _TP_DATA_PROTO_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 168 #define _TP_ARGS_DATA_VAR(...)          _TP_DATA_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 169 #define _TP_PARAMS(...)                 __VA_ARGS__
 170
 171 /*
 172  * The tracepoint cb is marked always inline so we can distinguish
 173  * between caller's ip addresses within the probe using the return
 174  * address.
 175  */
 176 #define _DECLARE_TRACEPOINT(_provider, _name, ...)                                      \
 177 extern struct lttng_ust_tracepoint __tracepoint_##_provider##___##_name;                \
 178 static inline __attribute__((always_inline, unused)) lttng_ust_notrace                  \
 179 void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__));              \
 180 static                                                                                  \
 181 void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__))               \
 182 {                                                                                       \
 183         struct lttng_ust_tracepoint_probe *__tp_probe;                                          \
 184                                                                                         \
 185         if (caa_unlikely(!TP_RCU_LINK_TEST()))                                          \
 186                 return;                                                                 \
 187         tp_rcu_read_lock_bp();                                                          \
 188         __tp_probe = tp_rcu_dereference_bp(__tracepoint_##_provider##___##_name.probes); \
 189         if (caa_unlikely(!__tp_probe))                                                  \
 190                 goto end;                                                               \
 191         do {                                                                            \
 192                 void (*__tp_cb)(void) = __tp_probe->func;                               \
 193                 void *__tp_data = __tp_probe->data;                                     \
 194                                                                                         \
 195                 URCU_FORCE_CAST(void (*)(_TP_ARGS_DATA_PROTO(__VA_ARGS__)), __tp_cb)    \
 196                                 (_TP_ARGS_DATA_VAR(__VA_ARGS__));                       \
 197         } while ((++__tp_probe)->func);                                                 \
 198 end:                                                                                    \
 199         tp_rcu_read_unlock_bp();                                                        \
 200 }                                                                                       \
 201 static inline lttng_ust_notrace                                                         \
 202 void __tracepoint_register_##_provider##___##_name(char *name,                          \
 203                 void (*func)(void), void *data);                                        \
 204 static inline                                                                           \
 205 void __tracepoint_register_##_provider##___##_name(char *name,                          \
 206                 void (*func)(void), void *data)                                         \
 207 {                                                                                       \
 208         __tracepoint_probe_register(name, func, data,                                   \
 209                 __tracepoint_##_provider##___##_name.signature);                        \
 210 }                                                                                       \
 211 static inline lttng_ust_notrace                                                         \
 212 void __tracepoint_unregister_##_provider##___##_name(char *name,                        \
 213                 void (*func)(void), void *data);                                        \
 214 static inline                                                                           \
 215 void __tracepoint_unregister_##_provider##___##_name(char *name,                        \
 216                 void (*func)(void), void *data)                                         \
 217 {                                                                                       \
 218         __tracepoint_probe_unregister(name, func, data);                                \
 219 }
 220
 221 extern int __tracepoint_probe_register(const char *name, void (*func)(void),
 222                 void *data, const char *signature);
 223 extern int __tracepoint_probe_unregister(const char *name, void (*func)(void),
 224                 void *data);
 225
 226 /*
 227  * tracepoint dynamic linkage handling (callbacks). Hidden visibility:
 228  * shared across objects in a module/main executable.
 229  */
 230 struct lttng_ust_tracepoint_dlopen {
 231         void *liblttngust_handle;
 232
 233         int (*tracepoint_register_lib)(struct lttng_ust_tracepoint * const *tracepoints_start,
 234                 int tracepoints_count);
 235         int (*tracepoint_unregister_lib)(struct lttng_ust_tracepoint * const *tracepoints_start);
 236         void (*rcu_read_lock_sym_bp)(void);
 237         void (*rcu_read_unlock_sym_bp)(void);
 238         void *(*rcu_dereference_sym_bp)(void *p);
 239 };
 240
 241 extern struct lttng_ust_tracepoint_dlopen tracepoint_dlopen;
 242 extern struct lttng_ust_tracepoint_dlopen *tracepoint_dlopen_ptr;
 243
 244 /*
 245  * These weak symbols, the constructor, and destructor take care of
 246  * registering only _one_ instance of the tracepoints per shared-ojbect
 247  * (or for the whole main program).
 248  */
 249 int __tracepoint_registered
 250         __attribute__((weak, visibility("hidden")));
 251 int __tracepoint_ptrs_registered
 252         __attribute__((weak, visibility("hidden")));
 253 struct lttng_ust_tracepoint_dlopen tracepoint_dlopen
 254         __attribute__((weak, visibility("hidden")));
 255 /*
 256  * Deal with gcc O1 optimisation issues with weak hidden symbols. gcc
 257  * 4.8 and prior does not have the same behavior for symbol scoping on
 258  * 32-bit powerpc depending on the object size: symbols for objects of 8
 259  * bytes or less have the same address throughout a module, whereas they
 260  * have different addresses between compile units for objects larger
 261  * than 8 bytes. Add this pointer indirection to ensure that the symbol
 262  * scoping match that of the other weak hidden symbols found in this
 263  * header.
 264  */
 265 struct lttng_ust_tracepoint_dlopen *tracepoint_dlopen_ptr
 266         __attribute__((weak, visibility("hidden")));
 267
 268 /*
 269  * Tracepoint dynamic linkage handling (callbacks). Hidden visibility: shared
 270  * across objects in a module/main executable. The callbacks are used to
 271  * control and check if the destructors should be executed.
 272  */
 273 struct lttng_ust_tracepoint_destructors_syms {
 274         int *old_tracepoint_disable_destructors;
 275         void (*tracepoint_disable_destructors)(void);
 276         int (*tracepoint_get_destructors_state)(void);
 277 };
 278
 279 extern struct lttng_ust_tracepoint_destructors_syms tracepoint_destructors_syms;
 280 extern struct lttng_ust_tracepoint_destructors_syms *tracepoint_destructors_syms_ptr;
 281
 282 struct lttng_ust_tracepoint_destructors_syms tracepoint_destructors_syms
 283         __attribute__((weak, visibility("hidden")));
 284 struct lttng_ust_tracepoint_destructors_syms *tracepoint_destructors_syms_ptr
 285         __attribute__((weak, visibility("hidden")));
 286
 287 static inline void tracepoint_disable_destructors(void)
 288 {
 289         if (!tracepoint_dlopen_ptr)
 290                 tracepoint_dlopen_ptr = &tracepoint_dlopen;
 291         if (!tracepoint_destructors_syms_ptr)
 292                 tracepoint_destructors_syms_ptr = &tracepoint_destructors_syms;
 293         if (tracepoint_dlopen_ptr->liblttngust_handle
 294                         && tracepoint_destructors_syms_ptr->tracepoint_disable_destructors)
 295                 tracepoint_destructors_syms_ptr->tracepoint_disable_destructors();
 296         *tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors = 1;
 297 }
 298
 299 #ifndef _LGPL_SOURCE
 300 static inline void lttng_ust_notrace
 301 __tracepoint__init_urcu_sym(void);
 302 static inline void
 303 __tracepoint__init_urcu_sym(void)
 304 {
 305         if (!tracepoint_dlopen_ptr)
 306                 tracepoint_dlopen_ptr = &tracepoint_dlopen;
 307         /*
 308          * Symbols below are needed by tracepoint call sites and probe
 309          * providers.
 310          */
 311         if (!tracepoint_dlopen_ptr->rcu_read_lock_sym_bp)
 312                 tracepoint_dlopen_ptr->rcu_read_lock_sym_bp =
 313                         URCU_FORCE_CAST(void (*)(void),
 314                                 dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
 315                                         "tp_rcu_read_lock_bp"));
 316         if (!tracepoint_dlopen_ptr->rcu_read_unlock_sym_bp)
 317                 tracepoint_dlopen_ptr->rcu_read_unlock_sym_bp =
 318                         URCU_FORCE_CAST(void (*)(void),
 319                                 dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
 320                                         "tp_rcu_read_unlock_bp"));
 321         if (!tracepoint_dlopen_ptr->rcu_dereference_sym_bp)
 322                 tracepoint_dlopen_ptr->rcu_dereference_sym_bp =
 323                         URCU_FORCE_CAST(void *(*)(void *p),
 324                                 dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
 325                                         "tp_rcu_dereference_sym_bp"));
 326 }
 327 #else
 328 static inline void lttng_ust_notrace
 329 __tracepoint__init_urcu_sym(void);
 330 static inline void
 331 __tracepoint__init_urcu_sym(void)
 332 {
 333 }
 334 #endif
 335
 336 static void lttng_ust_notrace __attribute__((constructor))
 337 __tracepoints__init(void);
 338 static void
 339 __tracepoints__init(void)
 340 {
 341         if (__tracepoint_registered++) {
 342                 if (!tracepoint_dlopen_ptr->liblttngust_handle)
 343                         return;
 344                 __tracepoint__init_urcu_sym();
 345                 return;
 346         }
 347
 348         if (!tracepoint_dlopen_ptr)
 349                 tracepoint_dlopen_ptr = &tracepoint_dlopen;
 350         if (!tracepoint_dlopen_ptr->liblttngust_handle)
 351                 tracepoint_dlopen_ptr->liblttngust_handle =
 352                         dlopen("liblttng-ust-tracepoint.so.0", RTLD_NOW | RTLD_GLOBAL);
 353         if (!tracepoint_dlopen_ptr->liblttngust_handle)
 354                 return;
 355         __tracepoint__init_urcu_sym();
 356 }
 357
 358 static void lttng_ust_notrace __attribute__((destructor))
 359 __tracepoints__destroy(void);
 360 static void
 361 __tracepoints__destroy(void)
 362 {
 363         int ret;
 364
 365         if (--__tracepoint_registered)
 366                 return;
 367         if (!tracepoint_dlopen_ptr)
 368                 tracepoint_dlopen_ptr = &tracepoint_dlopen;
 369         if (!tracepoint_destructors_syms_ptr)
 370                 tracepoint_destructors_syms_ptr = &tracepoint_destructors_syms;
 371         if (!tracepoint_dlopen_ptr->liblttngust_handle)
 372                 return;
 373         if (__tracepoint_ptrs_registered)
 374                 return;
 375         /*
 376          * Lookup if destructors must be executed using the new method.
 377          */
 378         if (tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state
 379                 && !tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state()) {
 380                 /*
 381                  * The tracepoint_get_destructors_state symbol was found with
 382                  * dlsym but its returned value is 0 meaning that destructors
 383                  * must not be executed.
 384                  */
 385                 return;
 386         }
 387         /*
 388          * Lookup if destructors must be executed using the old method.
 389          */
 390         if (tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors
 391                 && *tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors) {
 392                 /*
 393                  * The old_tracepoint_disable_destructors symbol was found with
 394                  * dlsym but its value is 1 meaning that destructors must not
 395                  * be executed.
 396                  */
 397                 return;
 398         }
 399
 400         ret = dlclose(tracepoint_dlopen_ptr->liblttngust_handle);
 401         if (ret) {
 402                 fprintf(stderr, "Error (%d) in dlclose\n", ret);
 403                 abort();
 404         }
 405         memset(tracepoint_dlopen_ptr, 0, sizeof(*tracepoint_dlopen_ptr));
 406 }
 407
 408 #ifdef TRACEPOINT_DEFINE
 409
 410 /*
 411  * These weak symbols, the constructor, and destructor take care of
 412  * registering only _one_ instance of the tracepoints per shared-ojbect
 413  * (or for the whole main program).
 414  */
 415 extern struct lttng_ust_tracepoint * const __start___tracepoints_ptrs[]
 416         __attribute__((weak, visibility("hidden")));
 417 extern struct lttng_ust_tracepoint * const __stop___tracepoints_ptrs[]
 418         __attribute__((weak, visibility("hidden")));
 419
 420 /*
 421  * When TRACEPOINT_PROBE_DYNAMIC_LINKAGE is defined, we do not emit a
 422  * unresolved symbol that requires the provider to be linked in. When
 423  * TRACEPOINT_PROBE_DYNAMIC_LINKAGE is not defined, we emit an
 424  * unresolved symbol that depends on having the provider linked in,
 425  * otherwise the linker complains. This deals with use of static
 426  * libraries, ensuring that the linker does not remove the provider
 427  * object from the executable.
 428  */
 429 #ifdef TRACEPOINT_PROBE_DYNAMIC_LINKAGE
 430 #define _TRACEPOINT_UNDEFINED_REF(provider)     NULL
 431 #else   /* TRACEPOINT_PROBE_DYNAMIC_LINKAGE */
 432 #define _TRACEPOINT_UNDEFINED_REF(provider)     &__tracepoint_provider_##provider
 433 #endif /* TRACEPOINT_PROBE_DYNAMIC_LINKAGE */
 434
 435 /*
 436  * Note: to allow PIC code, we need to allow the linker to update the pointers
 437  * in the __tracepoints_ptrs section.
 438  * Therefore, this section is _not_ const (read-only).
 439  */
 440 #define _TP_EXTRACT_STRING(...) #__VA_ARGS__
 441
 442 #define _DEFINE_TRACEPOINT(_provider, _name, _args)                             \
 443         extern int __tracepoint_provider_##_provider;                           \
 444         static const char __tp_strtab_##_provider##___##_name[]                 \
 445                 __attribute__((section("__tracepoints_strings"))) =             \
 446                         #_provider ":" #_name;                                  \
 447         struct lttng_ust_tracepoint __tracepoint_##_provider##___##_name        \
 448                 __attribute__((section("__tracepoints"))) =                     \
 449                 {                                                               \
 450                         __tp_strtab_##_provider##___##_name,                    \
 451                         0,                                                      \
 452                         NULL,                                                   \
 453                         _TRACEPOINT_UNDEFINED_REF(_provider),                   \
 454                         _TP_EXTRACT_STRING(_args),                              \
 455                         { },                                                    \
 456                 };                                                              \
 457         static struct lttng_ust_tracepoint *                                    \
 458                 __tracepoint_ptr_##_provider##___##_name                        \
 459                 __attribute__((section("__tracepoints_ptrs"), used))            \
 460                 __lttng_ust_variable_attribute_no_sanitize_address =            \
 461                         &__tracepoint_##_provider##___##_name;
 462
 463 static void lttng_ust_notrace __attribute__((constructor))
 464 __tracepoints__ptrs_init(void);
 465 static void
 466 __tracepoints__ptrs_init(void)
 467 {
 468         if (__tracepoint_ptrs_registered++)
 469                 return;
 470         if (!tracepoint_dlopen_ptr)
 471                 tracepoint_dlopen_ptr = &tracepoint_dlopen;
 472         if (!tracepoint_dlopen_ptr->liblttngust_handle)
 473                 tracepoint_dlopen_ptr->liblttngust_handle =
 474                         dlopen("liblttng-ust-tracepoint.so.0", RTLD_NOW | RTLD_GLOBAL);
 475         if (!tracepoint_dlopen_ptr->liblttngust_handle)
 476                 return;
 477         if (!tracepoint_destructors_syms_ptr)
 478                 tracepoint_destructors_syms_ptr = &tracepoint_destructors_syms;
 479         tracepoint_dlopen_ptr->tracepoint_register_lib =
 480                 URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *, int),
 481                                 dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
 482                                         "tracepoint_register_lib"));
 483         tracepoint_dlopen_ptr->tracepoint_unregister_lib =
 484                 URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *),
 485                                 dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
 486                                         "tracepoint_unregister_lib"));
 487         tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors =
 488                 URCU_FORCE_CAST(int *,
 489                                 dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
 490                                         "__tracepoints__disable_destructors"));
 491         tracepoint_destructors_syms_ptr->tracepoint_disable_destructors =
 492                 URCU_FORCE_CAST(void (*)(void),
 493                                 dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
 494                                         "tp_disable_destructors"));
 495         tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state =
 496                 URCU_FORCE_CAST(int (*)(void),
 497                                 dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
 498                                         "tp_get_destructors_state"));
 499         __tracepoint__init_urcu_sym();
 500         if (tracepoint_dlopen_ptr->tracepoint_register_lib) {
 501                 tracepoint_dlopen_ptr->tracepoint_register_lib(__start___tracepoints_ptrs,
 502                                 __stop___tracepoints_ptrs -
 503                                 __start___tracepoints_ptrs);
 504         }
 505 }
 506
 507 static void lttng_ust_notrace __attribute__((destructor))
 508 __tracepoints__ptrs_destroy(void);
 509 static void
 510 __tracepoints__ptrs_destroy(void)
 511 {
 512         int ret;
 513
 514         if (--__tracepoint_ptrs_registered)
 515                 return;
 516         if (!tracepoint_dlopen_ptr)
 517                 tracepoint_dlopen_ptr = &tracepoint_dlopen;
 518         if (!tracepoint_destructors_syms_ptr)
 519                 tracepoint_destructors_syms_ptr = &tracepoint_destructors_syms;
 520         if (tracepoint_dlopen_ptr->tracepoint_unregister_lib)
 521                 tracepoint_dlopen_ptr->tracepoint_unregister_lib(__start___tracepoints_ptrs);
 522         if (tracepoint_dlopen_ptr->liblttngust_handle
 523                         && tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state
 524                         && tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state()
 525                         && !__tracepoint_ptrs_registered) {
 526                 ret = dlclose(tracepoint_dlopen_ptr->liblttngust_handle);
 527                 if (ret) {
 528                         fprintf(stderr, "Error (%d) in dlclose\n", ret);
 529                         abort();
 530                 }
 531                 memset(tracepoint_dlopen_ptr, 0, sizeof(*tracepoint_dlopen_ptr));
 532         }
 533 }
 534
 535 #else /* TRACEPOINT_DEFINE */
 536
 537 #define _DEFINE_TRACEPOINT(_provider, _name, _args)
 538
 539 #endif /* #else TRACEPOINT_DEFINE */
 540
 541 #ifdef __cplusplus
 542 }
 543 #endif
 544
 545 #endif /* _LTTNG_TRACEPOINT_H */
 546
 547 /* The following declarations must be outside re-inclusion protection. */
 548
 549 #ifndef TRACEPOINT_ENUM
 550
 551 /*
 552  * Tracepoint Enumerations
 553  *
 554  * The enumeration is a mapping between an integer, or range of integers, and
 555  * a string. It can be used to have a more compact trace in cases where the
 556  * possible values for a field are limited:
 557  *
 558  * An example:
 559  *
 560  * TRACEPOINT_ENUM(someproject_component, enumname,
 561  *      TP_ENUM_VALUES(
 562  *              ctf_enum_value("even", 0)
 563  *              ctf_enum_value("uneven", 1)
 564  *              ctf_enum_range("twoto4", 2, 4)
 565  *              ctf_enum_value("five", 5)
 566  *      )
 567  * )
 568  *
 569  * Where "someproject_component" is the name of the component this enumeration
 570  * belongs to and "enumname" identifies this enumeration. Inside the
 571  * TP_ENUM_VALUES macro is the actual mapping. Each string value can map
 572  * to either a single value with ctf_enum_value or a range of values
 573  * with ctf_enum_range.
 574  *
 575  * Enumeration ranges may overlap, but the behavior is implementation-defined,
 576  * each trace reader will handle overlapping as it wishes.
 577  *
 578  * That enumeration can then be used in a field inside the TP_FIELD macro using
 579  * the following line:
 580  *
 581  * ctf_enum(someproject_component, enumname, enumtype, enumfield, enumval)
 582  *
 583  * Where "someproject_component" and "enumname" match those in the
 584  * TRACEPOINT_ENUM, "enumtype" is a signed or unsigned integer type
 585  * backing the enumeration, "enumfield" is the name of the field and
 586  * "enumval" is the value.
 587  */
 588
 589 #define TRACEPOINT_ENUM(provider, name, values)
 590
 591 #endif /* #ifndef TRACEPOINT_ENUM */
 592
 593 #ifndef TRACEPOINT_EVENT
 594
 595 /*
 596  * How to use the TRACEPOINT_EVENT macro:
 597  *
 598  * An example:
 599  *
 600  * TRACEPOINT_EVENT(someproject_component, event_name,
 601  *
 602  *     * TP_ARGS takes from 0 to 10 "type, field_name" pairs *
 603  *
 604  *     TP_ARGS(int, arg0, void *, arg1, char *, string, size_t, strlen,
 605  *             long *, arg4, size_t, arg4_len),
 606  *
 607  *      * TP_FIELDS describes the event payload layout in the trace *
 608  *
 609  *     TP_FIELDS(
 610  *         * Integer, printed in base 10 *
 611  *         ctf_integer(int, field_a, arg0)
 612  *
 613  *         * Integer, printed with 0x base 16 *
 614  *         ctf_integer_hex(unsigned long, field_d, arg1)
 615  *
 616  *         * Enumeration *
 617  *         ctf_enum(someproject_component, enum_name, int, field_e, arg0)
 618  *
 619  *         * Array Sequence, printed as UTF8-encoded array of bytes *
 620  *         ctf_array_text(char, field_b, string, FIXED_LEN)
 621  *         ctf_sequence_text(char, field_c, string, size_t, strlen)
 622  *
 623  *         * String, printed as UTF8-encoded string *
 624  *         ctf_string(field_e, string)
 625  *
 626  *         * Array sequence of signed integer values *
 627  *         ctf_array(long, field_f, arg4, FIXED_LEN4)
 628  *         ctf_sequence(long, field_g, arg4, size_t, arg4_len)
 629  *     )
 630  * )
 631  *
 632  * More detailed explanation:
 633  *
 634  * The name of the tracepoint is expressed as a tuple with the provider
 635  * and name arguments.
 636  *
 637  * The provider and name should be a proper C99 identifier.
 638  * The "provider" and "name" MUST follow these rules to ensure no
 639  * namespace clash occurs:
 640  *
 641  * For projects (applications and libraries) for which an entity
 642  * specific to the project controls the source code and thus its
 643  * tracepoints (typically with a scope larger than a single company):
 644  *
 645  * either:
 646  *   project_component, event
 647  * or:
 648  *   project, event
 649  *
 650  * Where "project" is the name of the project,
 651  *       "component" is the name of the project component (which may
 652  *       include several levels of sub-components, e.g.
 653  *       ...component_subcomponent_...) where the tracepoint is located
 654  *       (optional),
 655  *       "event" is the name of the tracepoint event.
 656  *
 657  * For projects issued from a single company wishing to advertise that
 658  * the company controls the source code and thus the tracepoints, the
 659  * "com_" prefix should be used:
 660  *
 661  * either:
 662  *   com_company_project_component, event
 663  * or:
 664  *   com_company_project, event
 665  *
 666  * Where "company" is the name of the company,
 667  *       "project" is the name of the project,
 668  *       "component" is the name of the project component (which may
 669  *       include several levels of sub-components, e.g.
 670  *       ...component_subcomponent_...) where the tracepoint is located
 671  *       (optional),
 672  *       "event" is the name of the tracepoint event.
 673  *
 674  * the provider:event identifier is limited to 127 characters.
 675  */
 676
 677 #define TRACEPOINT_EVENT(provider, name, args, fields)                  \
 678         _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))           \
 679         _DEFINE_TRACEPOINT(provider, name, _TP_PARAMS(args))
 680
 681 #define TRACEPOINT_EVENT_CLASS(provider, name, args, fields)
 682
 683 #define TRACEPOINT_EVENT_INSTANCE(provider, _template, name, args)      \
 684         _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))           \
 685         _DEFINE_TRACEPOINT(provider, name, _TP_PARAMS(args))
 686
 687 #endif /* #ifndef TRACEPOINT_EVENT */
 688
 689 #ifndef TRACEPOINT_LOGLEVEL
 690
 691 /*
 692  * Tracepoint Loglevels
 693  *
 694  * Typical use of these loglevels:
 695  *
 696  * The loglevels go from 0 to 14. Higher numbers imply the most
 697  * verbosity (higher event throughput expected.
 698  *
 699  * Loglevels 0 through 6, and loglevel 14, match syslog(3) loglevels
 700  * semantic. Loglevels 7 through 13 offer more fine-grained selection of
 701  * debug information.
 702  *
 703  * TRACE_EMERG           0
 704  * system is unusable
 705  *
 706  * TRACE_ALERT           1
 707  * action must be taken immediately
 708  *
 709  * TRACE_CRIT            2
 710  * critical conditions
 711  *
 712  * TRACE_ERR             3
 713  * error conditions
 714  *
 715  * TRACE_WARNING         4
 716  * warning conditions
 717  *
 718  * TRACE_NOTICE          5
 719  * normal, but significant, condition
 720  *
 721  * TRACE_INFO            6
 722  * informational message
 723  *
 724  * TRACE_DEBUG_SYSTEM    7
 725  * debug information with system-level scope (set of programs)
 726  *
 727  * TRACE_DEBUG_PROGRAM   8
 728  * debug information with program-level scope (set of processes)
 729  *
 730  * TRACE_DEBUG_PROCESS   9
 731  * debug information with process-level scope (set of modules)
 732  *
 733  * TRACE_DEBUG_MODULE    10
 734  * debug information with module (executable/library) scope (set of units)
 735  *
 736  * TRACE_DEBUG_UNIT      11
 737  * debug information with compilation unit scope (set of functions)
 738  *
 739  * TRACE_DEBUG_FUNCTION  12
 740  * debug information with function-level scope
 741  *
 742  * TRACE_DEBUG_LINE      13
 743  * debug information with line-level scope (TRACEPOINT_EVENT default)
 744  *
 745  * TRACE_DEBUG           14
 746  * debug-level message
 747  *
 748  * Declare tracepoint loglevels for tracepoints. A TRACEPOINT_EVENT
 749  * should be declared prior to the the TRACEPOINT_LOGLEVEL for a given
 750  * tracepoint name. The first field is the provider name, the second
 751  * field is the name of the tracepoint, the third field is the loglevel
 752  * name.
 753  *
 754  *      TRACEPOINT_LOGLEVEL(< [com_company_]project[_component] >, < event >,
 755  *              < loglevel_name >)
 756  *
 757  * The TRACEPOINT_PROVIDER must be already declared before declaring a
 758  * TRACEPOINT_LOGLEVEL.
 759  */
 760
 761 enum {
 762         TRACE_EMERG             = 0,
 763         TRACE_ALERT             = 1,
 764         TRACE_CRIT              = 2,
 765         TRACE_ERR               = 3,
 766         TRACE_WARNING           = 4,
 767         TRACE_NOTICE            = 5,
 768         TRACE_INFO              = 6,
 769         TRACE_DEBUG_SYSTEM      = 7,
 770         TRACE_DEBUG_PROGRAM     = 8,
 771         TRACE_DEBUG_PROCESS     = 9,
 772         TRACE_DEBUG_MODULE      = 10,
 773         TRACE_DEBUG_UNIT        = 11,
 774         TRACE_DEBUG_FUNCTION    = 12,
 775         TRACE_DEBUG_LINE        = 13,
 776         TRACE_DEBUG             = 14,
 777 };
 778
 779 #define TRACEPOINT_LOGLEVEL(provider, name, loglevel)
 780
 781 #endif /* #ifndef TRACEPOINT_LOGLEVEL */
 782
 783 #ifndef TRACEPOINT_MODEL_EMF_URI
 784
 785 #define TRACEPOINT_MODEL_EMF_URI(provider, name, uri)
 786
 787 #endif /* #ifndef TRACEPOINT_MODEL_EMF_URI */