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