include/ust/tracepoint.h

   1 #ifndef _UST_TRACEPOINT_H
   2 #define _UST_TRACEPOINT_H
   3
   4 /*
   5  * Copyright (C) 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   6  * Copyright (C) 2009 Pierre-Marc Fournier
   7  * Copyright (C) 2009 Steven Rostedt <rostedt@goodmis.org>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation;
  12  * version 2.1 of the License.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  22  *
  23  * Heavily inspired from the Linux Kernel Markers.
  24  *
  25  * Ported to userspace by Pierre-Marc Fournier.
  26  */
  27
  28 #include <urcu-bp.h>
  29 #include <urcu/list.h>
  30
  31 struct tracepoint_probe {
  32         void *func;
  33         void *data;
  34 };
  35
  36 struct tracepoint {
  37         const char *name;               /* Tracepoint name */
  38         char state;                     /* State. */
  39         struct tracepoint_probe *probes;
  40 };
  41
  42 /*
  43  * Tracepoints should be added to the instrumented code using the
  44  * "tracepoint()" macro.
  45  */
  46 #define tracepoint(name, args...)       __trace_##name(args)
  47
  48 /*
  49  * Library should be made known to libust by declaring TRACEPOINT_LIB in
  50  * the source file. (Usually at the end of the file, in the outermost
  51  * scope).
  52  */
  53 #define TRACEPOINT_LIB                                                  \
  54         extern struct tracepoint * const __start___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \
  55         extern struct tracepoint * const __stop___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \
  56         static struct tracepoint * __tracepoint_ptr_dummy               \
  57         __attribute__((used, section("__tracepoints_ptrs")));           \
  58         static void __attribute__((constructor)) __tracepoints__init(void) \
  59         {                                                               \
  60                 tracepoint_register_lib(__start___tracepoints_ptrs,     \
  61                                         __stop___tracepoints_ptrs -     \
  62                                         __start___tracepoints_ptrs);    \
  63         }                                                               \
  64                                                                         \
  65         static void __attribute__((destructor)) __tracepoints__destroy(void) \
  66         {                                                               \
  67                 tracepoint_unregister_lib(__start___tracepoints_ptrs);  \
  68         }
  69
  70 /*
  71  * it_func[0] is never NULL because there is at least one element in the array
  72  * when the array itself is non NULL.
  73  * __attribute__((unused)) is for backward compatibility API.
  74  */
  75 #define __DO_TRACE(tp, proto, args)                                     \
  76         do {                                                            \
  77                 struct tracepoint_probe *__tp_it_probe_ptr;             \
  78                 void *__tp_it_func;                                     \
  79                 void *__tp_cb_data __attribute__((unused));             \
  80                                                                         \
  81                 rcu_read_lock();                                        \
  82                 __tp_it_probe_ptr = rcu_dereference((tp)->probes);      \
  83                 if (__tp_it_probe_ptr) {                                \
  84                         do {                                            \
  85                                 __tp_it_func = __tp_it_probe_ptr->func; \
  86                                 __tp_cb_data = __tp_it_probe_ptr->data; \
  87                                 ((void(*)(proto))__tp_it_func)(args);   \
  88                         } while ((++__tp_it_probe_ptr)->func);          \
  89                 }                                                       \
  90                 rcu_read_unlock();                                      \
  91         } while (0)
  92
  93 #define TP_PARAMS(args...)      args
  94 #define TP_PROTO(args...)       args
  95 #define TP_ARGS(args...)        args
  96
  97 #define __CHECK_TRACE(name, proto, args)                                \
  98         do {                                                            \
  99                 if (unlikely(__tracepoint_##name.state))                \
 100                         __DO_TRACE(&__tracepoint_##name,                \
 101                                 TP_PROTO(proto), TP_ARGS(args));        \
 102         } while (0)
 103
 104 /*
 105  * Make sure the alignment of the structure in the __tracepoints section will
 106  * not add unwanted padding between the beginning of the section and the
 107  * structure. Force alignment to the same alignment as the section start.
 108  */
 109 #define __DECLARE_TRACEPOINT(name, proto, args, data_proto, data_args)  \
 110         extern struct tracepoint __tracepoint_##name;                   \
 111         static inline void __trace_##name(proto)                        \
 112         {                                                               \
 113                 __CHECK_TRACE(name, TP_PROTO(data_proto),               \
 114                               TP_ARGS(data_args));                      \
 115         }                                                               \
 116         static inline int                                               \
 117         __register_trace_##name(void (*probe)(data_proto), void *data)  \
 118         {                                                               \
 119                 return __tracepoint_probe_register(#name, (void *)probe,\
 120                                                  data);                 \
 121                                                                         \
 122         }                                                               \
 123         static inline int                                               \
 124         __unregister_trace_##name(void (*probe)(data_proto), void *data)\
 125         {                                                               \
 126                 return __tracepoint_probe_unregister(#name, (void *)probe, \
 127                                                    data);               \
 128         }                                                               \
 129         /*                                                              \
 130          * Backward-compatibility API (will be deprecated):             \
 131          * trace_*                                                      \
 132          * register_trace_*                                             \
 133          * unregister_trace_*                                           \
 134          */                                                             \
 135         static inline void trace_##name(proto)                          \
 136         {                                                               \
 137                 __CHECK_TRACE(name, TP_PROTO(proto),                    \
 138                               TP_ARGS(args));                           \
 139         }                                                               \
 140         static inline int                                               \
 141         register_trace_##name(void (*probe)(proto))                     \
 142         {                                                               \
 143                 return __tracepoint_probe_register(#name, (void *)probe,\
 144                                                    NULL);               \
 145         }                                                               \
 146         static inline int                                               \
 147         unregister_trace_##name(void (*probe)(proto))                   \
 148         {                                                               \
 149                 return __tracepoint_probe_unregister(#name, (void *)probe, \
 150                                                      NULL);             \
 151         }
 152
 153 /*
 154  * The need for the _DECLARE_TRACEPOINT_NOARGS() is to handle the prototype
 155  * (void). "void" is a special value in a function prototype and can
 156  * not be combined with other arguments. Since the DECLARE_TRACEPOINT()
 157  * macro adds a data element at the beginning of the prototype,
 158  * we need a way to differentiate "(void *data, proto)" from
 159  * "(void *data, void)". The second prototype is invalid.
 160  *
 161  * DECLARE_TRACEPOINT_NOARGS() passes "void" as the tracepoint prototype
 162  * and "void *__tp_cb_data" as the callback prototype.
 163  *
 164  * DECLARE_TRACEPOINT() passes "proto" as the tracepoint protoype and
 165  * "void *__tp_cb_data, proto" as the callback prototype.
 166  */
 167 #define _DECLARE_TRACEPOINT_NOARGS(name)                                \
 168         __DECLARE_TRACEPOINT(name, void, , void *__tp_cb_data, __tp_cb_data)
 169
 170 #define _DECLARE_TRACEPOINT(name, proto, args)                          \
 171         __DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args),   \
 172                         TP_PARAMS(void *__tp_cb_data, proto),           \
 173                         TP_PARAMS(__tp_cb_data, args))
 174
 175 /*
 176  * __tracepoints_ptrs section is not const (read-only) to let the linker update
 177  * the pointer, allowing PIC code.
 178  */
 179 #define _DEFINE_TRACEPOINT(name)                                        \
 180         static const char __tpstrtab_##name[]                           \
 181         __attribute__((section("__tracepoints_strings"))) = #name;      \
 182         struct tracepoint __tracepoint_##name                           \
 183         __attribute__((section("__tracepoints"))) =                     \
 184                 { __tpstrtab_##name, 0, NULL };                         \
 185         static struct tracepoint * __tracepoint_ptr_##name              \
 186         __attribute__((used, section("__tracepoints_ptrs"))) =          \
 187                 &__tracepoint_##name;
 188
 189
 190 #define __register_tracepoint(name, probe, data)                        \
 191                 __register_trace_##name(probe, data)
 192 #define __unregister_tracepoint(name, probe, data)                      \
 193                 __unregister_trace_##name(probe, data)
 194
 195 /*
 196  * Connect a probe to a tracepoint.
 197  * Internal API.
 198  */
 199 extern
 200 int __tracepoint_probe_register(const char *name, void *probe, void *data);
 201
 202 /*
 203  * Disconnect a probe from a tracepoint.
 204  * Internal API.
 205  */
 206 extern
 207 int __tracepoint_probe_unregister(const char *name, void *probe, void *data);
 208
 209 struct tracepoint_lib {
 210         struct tracepoint * const *tracepoints_start;
 211         int tracepoints_count;
 212         struct cds_list_head list;
 213 };
 214
 215 extern
 216 int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
 217                             int tracepoints_count);
 218 extern
 219 int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start);
 220
 221 /*
 222  * Backward-compatibility API (will be deprecated):
 223  * DEFINE_TRACE
 224  * DECLARE_TRACE
 225  * register_tracepoint
 226  * unregister_tracepoint
 227  */
 228 #define DEFINE_TRACE    _DEFINE_TRACEPOINT
 229 #define DECLARE_TRACE(name, proto, args)        \
 230                 _DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args))
 231
 232 #ifndef TRACEPOINT_EVENT
 233 /*
 234  * For use with the TRACEPOINT_EVENT macro:
 235  *
 236  * We define a tracepoint, its arguments, its printf format
 237  * and its 'fast binary record' layout.
 238  *
 239  * Firstly, name your tracepoint via TRACEPOINT_EVENT(name : the
 240  * 'subsystem_event' notation is fine.
 241  *
 242  * Think about this whole construct as the
 243  * 'trace_sched_switch() function' from now on.
 244  *
 245  *
 246  *  TRACEPOINT_EVENT(sched_switch,
 247  *
 248  *      *
 249  *      * A function has a regular function arguments
 250  *      * prototype, declare it via TP_PROTO():
 251  *      *
 252  *
 253  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 254  *               struct task_struct *next),
 255  *
 256  *      *
 257  *      * Define the call signature of the 'function'.
 258  *      * (Design sidenote: we use this instead of a
 259  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 260  *      *
 261  *
 262  *      TP_ARGS(rq, prev, next),
 263  *
 264  *      *
 265  *      * Fast binary tracing: define the trace record via
 266  *      * TP_FIELDS(). You can think about it like a
 267  *      * regular C structure local variable definition.
 268  *      *
 269  *      * This is how the trace record is structured and will
 270  *      * be saved into the ring buffer. These are the fields
 271  *      * that will be exposed to readers.
 272  *      *
 273  *      * tp_field(pid_t, prev_pid, prev->pid) is equivalent
 274  *      * to a standard declaraton:
 275  *      *
 276  *      *       pid_t prev_pid;
 277  *      *
 278  *      * followed by an assignment:
 279  *      *
 280  *      *       prev_pid = prev->pid;
 281  *      *
 282  *      * tp_array(char, prev_comm, TASK_COMM_LEN, prev->comm) is
 283  *      * equivalent to:
 284  *      *
 285  *      *       char prev_comm[TASK_COMM_LEN];
 286  *      *
 287  *      * followed by an assignment:
 288  *      *
 289  *      *       memcpy(prev_comm, prev->comm, TASK_COMM_LEN);
 290  *      *
 291  *
 292  *      TP_FIELDS(
 293  *              tp_array(char,  prev_comm, TASK_COMM_LEN, prev->comm)
 294  *              tp_field(pid_t, prev_pid,  prev->pid)
 295  *              tp_field(int,   prev_prio, prev->prio)
 296  *              tp_array(char,  next_comm, TASK_COMM_LEN, next->comm)
 297  *              tp_field(pid_t, next_pid,  next->pid)
 298  *              tp_field(int,   next_prio, next->prio)
 299  *      )
 300  * );
 301  */
 302
 303 #define TRACEPOINT_EVENT(name, proto, args, fields)                     \
 304         _DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args))
 305
 306 #define TRACEPOINT_EVENT_CLASS(name, proto, args, fields)
 307 #define TRACEPOINT_EVENT_INSTANCE(template, name, proto, args)          \
 308         _DECLARE_TRACEPOINT(name, TP_PARAMS(proto), TP_PARAMS(args))
 309
 310 /*
 311  * Declaration of tracepoints that take 0 argument.
 312  */
 313 #define TRACEPOINT_EVENT_NOARGS(name, fields)                           \
 314         _DECLARE_TRACEPOINT_NOARGS(name)
 315
 316 #define TRACEPOINT_EVENT_CLASS_NOARGS(name, fields)
 317 #define TRACEPOINT_EVENT_INSTANCE_NOARGS(template, name)                \
 318         _DECLARE_TRACEPOINT_NOARGS(name)
 319
 320
 321
 322 #define TRACEPOINT_EVENT_LIB                                            \
 323         extern struct trace_event * const __start___trace_events_ptrs[] \
 324         __attribute__((weak, visibility("hidden")));                    \
 325         extern struct trace_event * const __stop___trace_events_ptrs[]  \
 326         __attribute__((weak, visibility("hidden")));                    \
 327         static struct trace_event * __event_ptrs_dummy                  \
 328         __attribute__((used, section("__trace_events_ptrs")));          \
 329         static void __attribute__((constructor))                        \
 330         __trace_events__init(void)                                      \
 331         {                                                               \
 332                 trace_event_register_lib(__start___trace_events_ptrs,   \
 333                                          __stop___trace_events_ptrs -   \
 334                                          __start___trace_events_ptrs);  \
 335         }                                                               \
 336                                                                         \
 337         static void __attribute__((destructor))                         \
 338         __trace_event__destroy(void)                                    \
 339         {                                                               \
 340                 trace_event_unregister_lib(__start___trace_events_ptrs);\
 341         }
 342
 343 struct trace_event {
 344         const char *name;
 345 };
 346
 347 struct trace_event_lib {
 348         struct trace_event * const *trace_events_start;
 349         int trace_events_count;
 350         struct cds_list_head list;
 351 };
 352
 353 extern
 354 int trace_event_register_lib(struct trace_event * const *start_trace_events,
 355                              int trace_event_count);
 356 extern
 357 int trace_event_unregister_lib(struct trace_event * const *start_trace_events);
 358
 359 #endif /* #ifndef TRACEPOINT_EVENT */
 360
 361 #endif /* _UST_TRACEPOINT_H */