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; either
  12  * version 2.1 of the License, or (at your option) any later version.
  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 #define _LGPL_SOURCE
  29 #include <urcu-bp.h>
  30 #include <ust/core.h>
  31
  32 struct tracepoint;
  33
  34 struct probe {
  35         void *func;
  36         void *data;
  37 };
  38
  39 struct tracepoint {
  40         const char *name;               /* Tracepoint name */
  41         char state;                     /* State. */
  42         struct probe *probes;
  43 };
  44
  45 #define PARAMS(args...) args
  46
  47 #define TP_PROTO(args...)       args
  48 #define TP_ARGS(args...)        args
  49
  50 /*
  51  * Tracepoints should be added to the instrumented code using the
  52  * "tracepoint()" macro.
  53  */
  54 #define tracepoint(name, args...)       __trace_##name(args)
  55
  56 #define register_tracepoint(name, probe, data)                  \
  57                 __register_trace_##name(probe, data)
  58
  59 #define unregister_tracepoint(name, probe, data)                \
  60                 __unregister_trace_##name(probe, data)
  61
  62 #define CONFIG_TRACEPOINTS
  63 #ifdef CONFIG_TRACEPOINTS
  64
  65 /*
  66  * it_func[0] is never NULL because there is at least one element in the array
  67  * when the array itself is non NULL.
  68  */
  69 #define __DO_TRACE(tp, proto, args)                                     \
  70         do {                                                            \
  71                 struct probe *it_probe_ptr;                             \
  72                 void *it_func;                                          \
  73                 void *__data;                                           \
  74                                                                         \
  75                 rcu_read_lock();                                        \
  76                 it_probe_ptr = rcu_dereference((tp)->probes);           \
  77                 if (it_probe_ptr) {                                     \
  78                         do {                                            \
  79                                 it_func = (it_probe_ptr)->func;         \
  80                                 __data = (it_probe_ptr)->data;          \
  81                                 ((void(*)(proto))(it_func))(args);      \
  82                         } while ((++it_probe_ptr)->func);               \
  83                 }                                                       \
  84                 rcu_read_unlock();                                      \
  85         } while (0)
  86
  87 #define __CHECK_TRACE(name, proto, args)                                \
  88         do {                                                            \
  89                 if (unlikely(__tracepoint_##name.state))                \
  90                         __DO_TRACE(&__tracepoint_##name,                \
  91                                 TP_PROTO(proto), TP_ARGS(args));        \
  92         } while (0)
  93
  94 /*
  95  * Make sure the alignment of the structure in the __tracepoints section will
  96  * not add unwanted padding between the beginning of the section and the
  97  * structure. Force alignment to the same alignment as the section start.
  98  */
  99 #define __DECLARE_TRACE(name, proto, args, data_proto, data_args)       \
 100         extern struct tracepoint __tracepoint_##name;                   \
 101         static inline void __trace_##name(proto)                        \
 102         {                                                               \
 103                 __CHECK_TRACE(name, TP_PROTO(data_proto),               \
 104                               TP_ARGS(data_args));                      \
 105         }                                                               \
 106         static inline int                                               \
 107         __register_trace_##name(void (*probe)(data_proto), void *data)  \
 108         {                                                               \
 109                 return tracepoint_probe_register(#name, (void *)probe,  \
 110                                                  data);                 \
 111                                                                         \
 112         }                                                               \
 113         static inline int                                               \
 114         __unregister_trace_##name(void (*probe)(data_proto), void *data)\
 115         {                                                               \
 116                 return tracepoint_probe_unregister(#name, (void *)probe, \
 117                                                    data);               \
 118         }
 119
 120 #define DEFINE_TRACE_FN(name, reg, unreg)                               \
 121         static const char __tpstrtab_##name[]                           \
 122         __attribute__((section("__tracepoints_strings"))) = #name;      \
 123         struct tracepoint __tracepoint_##name                           \
 124         __attribute__((section("__tracepoints"))) =                     \
 125                 { __tpstrtab_##name, 0, NULL };                         \
 126         static struct tracepoint * const __tracepoint_ptr_##name        \
 127         __attribute__((used, section("__tracepoints_ptrs"))) =          \
 128                 &__tracepoint_##name;
 129
 130 #define DEFINE_TRACE(name)                                              \
 131         DEFINE_TRACE_FN(name, NULL, NULL)
 132
 133 extern void tracepoint_update_probe_range(struct tracepoint * const *begin,
 134         struct tracepoint * const *end);
 135
 136 #else /* !CONFIG_TRACEPOINTS */
 137 #define __DECLARE_TRACE(name, proto, args)                              \
 138         static inline void trace_##name(proto)                          \
 139         { }                                                             \
 140         static inline void _trace_##name(proto)                         \
 141         { }                                                             \
 142         static inline int __register_trace_##name(void (*probe)(proto), void *data)     \
 143         {                                                               \
 144                 return -ENOSYS;                                         \
 145         }                                                               \
 146         static inline int __unregister_trace_##name(void (*probe)(proto), void *data)   \
 147         {                                                               \
 148                 return -ENOSYS;                                         \
 149         }
 150
 151 #define DEFINE_TRACE(name)
 152 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 153 #define EXPORT_TRACEPOINT_SYMBOL(name)
 154
 155 static inline void tracepoint_update_probe_range(struct tracepoint *begin,
 156         struct tracepoint *end)
 157 { }
 158 #endif /* CONFIG_TRACEPOINTS */
 159
 160 /*
 161  * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
 162  * (void). "void" is a special value in a function prototype and can
 163  * not be combined with other arguments. Since the DECLARE_TRACE()
 164  * macro adds a data element at the beginning of the prototype,
 165  * we need a way to differentiate "(void *data, proto)" from
 166  * "(void *data, void)". The second prototype is invalid.
 167  *
 168  * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
 169  * and "void *__data" as the callback prototype.
 170  *
 171  * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
 172  * "void *__data, proto" as the callback prototype.
 173  */
 174 #define DECLARE_TRACE_NOARGS(name)                                      \
 175                 __DECLARE_TRACE(name, void, , void *__data, __data)
 176
 177 #define DECLARE_TRACE(name, proto, args)                                \
 178                 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),      \
 179                                 PARAMS(void *__data, proto),            \
 180                                 PARAMS(__data, args))
 181
 182 /*
 183  * Connect a probe to a tracepoint.
 184  * Internal API, should not be used directly.
 185  */
 186 extern int tracepoint_probe_register(const char *name, void *probe, void *data);
 187
 188 /*
 189  * Disconnect a probe from a tracepoint.
 190  * Internal API, should not be used directly.
 191  */
 192 extern int tracepoint_probe_unregister(const char *name, void *probe, void *data);
 193
 194 extern int tracepoint_probe_register_noupdate(const char *name, void *probe,
 195                                               void *data);
 196 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
 197                                                 void *data);
 198 extern void tracepoint_probe_update_all(void);
 199
 200 struct tracepoint_iter {
 201         struct tracepoint_lib *lib;
 202         struct tracepoint * const *tracepoint;
 203 };
 204
 205 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
 206 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
 207 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
 208 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
 209 extern int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
 210         struct tracepoint * const *begin, struct tracepoint * const *end);
 211
 212 /*
 213  * tracepoint_synchronize_unregister must be called between the last tracepoint
 214  * probe unregistration and the end of module exit to make sure there is no
 215  * caller executing a probe when it is freed.
 216  */
 217 static inline void tracepoint_synchronize_unregister(void)
 218 {
 219 //ust// synchronize_sched();
 220 }
 221
 222 struct tracepoint_lib {
 223         struct tracepoint * const *tracepoints_start;
 224         int tracepoints_count;
 225         struct cds_list_head list;
 226 };
 227
 228 extern int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
 229                                    int tracepoints_count);
 230 extern int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start);
 231
 232 #define TRACEPOINT_LIB                                                  \
 233         extern struct tracepoint * const __start___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \
 234         extern struct tracepoint * const __stop___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \
 235         static struct tracepoint * const __tracepoint_ptr_dummy         \
 236         __attribute__((used, section("__tracepoints_ptrs"))) = NULL;    \
 237         static void __attribute__((constructor)) __tracepoints__init(void)      \
 238         {                                                                       \
 239                 tracepoint_register_lib(__start___tracepoints_ptrs,                     \
 240                                         __stop___tracepoints_ptrs -                     \
 241                                         __start___tracepoints_ptrs);                    \
 242         }                                                                       \
 243                                                                                 \
 244         static void __attribute__((destructor)) __tracepoints__destroy(void)    \
 245         {                                                                       \
 246                 tracepoint_unregister_lib(__start___tracepoints_ptrs);          \
 247         }
 248
 249
 250 #ifndef TRACE_EVENT
 251 /*
 252  * For use with the TRACE_EVENT macro:
 253  *
 254  * We define a tracepoint, its arguments, its printf format
 255  * and its 'fast binary record' layout.
 256  *
 257  * Firstly, name your tracepoint via TRACE_EVENT(name : the
 258  * 'subsystem_event' notation is fine.
 259  *
 260  * Think about this whole construct as the
 261  * 'trace_sched_switch() function' from now on.
 262  *
 263  *
 264  *  TRACE_EVENT(sched_switch,
 265  *
 266  *      *
 267  *      * A function has a regular function arguments
 268  *      * prototype, declare it via TP_PROTO():
 269  *      *
 270  *
 271  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 272  *               struct task_struct *next),
 273  *
 274  *      *
 275  *      * Define the call signature of the 'function'.
 276  *      * (Design sidenote: we use this instead of a
 277  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 278  *      *
 279  *
 280  *      TP_ARGS(rq, prev, next),
 281  *
 282  *      *
 283  *      * Fast binary tracing: define the trace record via
 284  *      * TP_STRUCT__entry(). You can think about it like a
 285  *      * regular C structure local variable definition.
 286  *      *
 287  *      * This is how the trace record is structured and will
 288  *      * be saved into the ring buffer. These are the fields
 289  *      * that will be exposed to readers.
 290  *      *
 291  *      * The declared 'local variable' is called '__entry'
 292  *      *
 293  *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
 294  *      *
 295  *      *       pid_t   prev_pid;
 296  *      *
 297  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 298  *      *
 299  *      *       char    prev_comm[TASK_COMM_LEN];
 300  *      *
 301  *
 302  *      TP_STRUCT__entry(
 303  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
 304  *              __field(        pid_t,  prev_pid                        )
 305  *              __field(        int,    prev_prio                       )
 306  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
 307  *              __field(        pid_t,  next_pid                        )
 308  *              __field(        int,    next_prio                       )
 309  *      ),
 310  *
 311  *      *
 312  *      * Assign the entry into the trace record, by embedding
 313  *      * a full C statement block into TP_fast_assign(). You
 314  *      * can refer to the trace record as '__entry' -
 315  *      * otherwise you can put arbitrary C code in here.
 316  *      *
 317  *      * Note: this C code will execute every time a trace event
 318  *      * happens, on an active tracepoint.
 319  *      *
 320  *
 321  *      TP_fast_assign(
 322  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 323  *              __entry->prev_pid       = prev->pid;
 324  *              __entry->prev_prio      = prev->prio;
 325  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 326  *              __entry->next_pid       = next->pid;
 327  *              __entry->next_prio      = next->prio;
 328  *      )
 329  *
 330  *      *
 331  *      * Formatted output of a trace record via TP_printf().
 332  *      * This is how the tracepoint will appear under debugging
 333  *      * of tracepoints.
 334  *      *
 335  *      * (raw-binary tracing wont actually perform this step.)
 336  *      *
 337  *
 338  *      TP_printf("task %s:%d [%d] ==> %s:%d [%d]",
 339  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 340  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
 341  *
 342  * );
 343  *
 344  * This macro construct is thus used for the regular printf format
 345  * tracing setup.
 346  *
 347  * A set of (un)registration functions can be passed to the variant
 348  * TRACE_EVENT_FN to perform any (un)registration work.
 349  */
 350
 351 struct trace_event {
 352         const char *name;
 353         int (*regfunc)(void *data);
 354         int (*unregfunc)(void *data);
 355 };
 356
 357 struct trace_event_lib {
 358         struct trace_event * const *trace_events_start;
 359         int trace_events_count;
 360         struct cds_list_head list;
 361 };
 362
 363 struct trace_event_iter {
 364         struct trace_event_lib *lib;
 365         struct trace_event * const *trace_event;
 366 };
 367
 368 extern void lock_trace_events(void);
 369 extern void unlock_trace_events(void);
 370
 371 extern void trace_event_iter_start(struct trace_event_iter *iter);
 372 extern void trace_event_iter_next(struct trace_event_iter *iter);
 373 extern void trace_event_iter_reset(struct trace_event_iter *iter);
 374
 375 extern int trace_event_get_iter_range(struct trace_event * const **trace_event,
 376                                       struct trace_event * const *begin,
 377                                       struct trace_event * const *end);
 378
 379 extern void trace_event_update_process(void);
 380 extern int is_trace_event_enabled(const char *channel, const char *name);
 381
 382 extern int trace_event_register_lib(struct trace_event * const *start_trace_events,
 383                                     int trace_event_count);
 384
 385 extern int trace_event_unregister_lib(struct trace_event * const *start_trace_events);
 386
 387 #define TRACE_EVENT_LIB                                                 \
 388         extern struct trace_event * const __start___trace_events_ptrs[] \
 389         __attribute__((weak, visibility("hidden")));                    \
 390         extern struct trace_event * const __stop___trace_events_ptrs[]  \
 391         __attribute__((weak, visibility("hidden")));                    \
 392         static struct trace_event * const __event_ptrs_dummy            \
 393         __attribute__((used, section("__trace_events_ptrs"))) = NULL;   \
 394         static void __attribute__((constructor))                        \
 395         __trace_events__init(void)                                      \
 396         {                                                               \
 397                 trace_event_register_lib(__start___trace_events_ptrs,   \
 398                                          __stop___trace_events_ptrs -   \
 399                                          __start___trace_events_ptrs);  \
 400         }                                                               \
 401                                                                         \
 402         static void __attribute__((destructor))                         \
 403         __trace_event__destroy(void)                                    \
 404         {                                                               \
 405                 trace_event_unregister_lib(__start___trace_events_ptrs);\
 406         }
 407
 408 #define DECLARE_TRACE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
 409 #define DEFINE_TRACE_EVENT(template, name, proto, args)         \
 410         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 411 #define DEFINE_TRACE_EVENT_PRINT(template, name, proto, args, print)    \
 412         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 413
 414 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
 415         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 416 #define TRACE_EVENT_FN(name, proto, args, struct,               \
 417                 assign, print, reg, unreg)                      \
 418         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 419
 420 #endif /* ifdef TRACE_EVENT (see note above) */
 421
 422
 423 #endif /* _UST_TRACEPOINT_H */