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 module;
  33 struct tracepoint;
  34
  35 struct probe {
  36         void *func;
  37         void *data;
  38 };
  39
  40 struct tracepoint {
  41         const char *name;               /* Tracepoint name */
  42         char state;                     /* State. */
  43         struct probe *probes;
  44 };
  45
  46 #define PARAMS(args...) args
  47
  48 #define TP_PROTO(args...)       args
  49 #define TP_ARGS(args...)        args
  50
  51 /*
  52  * Tracepoints should be added to the instrumented code using the
  53  * "tracepoint()" macro.
  54  */
  55 #define tracepoint(name, args...)       __trace_##name(args)
  56
  57 #define register_tracepoint(name, probe, data)                  \
  58                 __register_trace_##name(probe, data)
  59
  60 #define unregister_tracepoint(name, probe, data)                \
  61                 __unregister_trace_##name(probe, data)
  62
  63 #define CONFIG_TRACEPOINTS
  64 #ifdef CONFIG_TRACEPOINTS
  65
  66 /*
  67  * it_func[0] is never NULL because there is at least one element in the array
  68  * when the array itself is non NULL.
  69  */
  70 #define __DO_TRACE(tp, proto, args)                                     \
  71         do {                                                            \
  72                 struct probe *it_probe_ptr;                             \
  73                 void *it_func;                                          \
  74                 void *__data;                                           \
  75                                                                         \
  76                 rcu_read_lock();                                        \
  77                 it_probe_ptr = rcu_dereference((tp)->probes);           \
  78                 if (it_probe_ptr) {                                     \
  79                         do {                                            \
  80                                 it_func = (it_probe_ptr)->func;         \
  81                                 __data = (it_probe_ptr)->data;          \
  82                                 ((void(*)(proto))(it_func))(args);      \
  83                         } while ((++it_probe_ptr)->func);               \
  84                 }                                                       \
  85                 rcu_read_unlock();                                      \
  86         } while (0)
  87
  88 #define __CHECK_TRACE(name, proto, args)                                \
  89         do {                                                            \
  90                 if (unlikely(__tracepoint_##name.state))                \
  91                         __DO_TRACE(&__tracepoint_##name,                \
  92                                 TP_PROTO(proto), TP_ARGS(args));        \
  93         } while (0)
  94
  95 /*
  96  * Make sure the alignment of the structure in the __tracepoints section will
  97  * not add unwanted padding between the beginning of the section and the
  98  * structure. Force alignment to the same alignment as the section start.
  99  */
 100 #define __DECLARE_TRACE(name, proto, args, data_proto, data_args)       \
 101         extern struct tracepoint __tracepoint_##name;                   \
 102         static inline void __trace_##name(proto)                        \
 103         {                                                               \
 104                 __CHECK_TRACE(name, TP_PROTO(data_proto),               \
 105                               TP_ARGS(data_args));                      \
 106         }                                                               \
 107         static inline int                                               \
 108         __register_trace_##name(void (*probe)(data_proto), void *data)  \
 109         {                                                               \
 110                 return tracepoint_probe_register(#name, (void *)probe,  \
 111                                                  data);                 \
 112                                                                         \
 113         }                                                               \
 114         static inline int                                               \
 115         __unregister_trace_##name(void (*probe)(data_proto), void *data)\
 116         {                                                               \
 117                 return tracepoint_probe_unregister(#name, (void *)probe, \
 118                                                    data);               \
 119         }
 120
 121 #define DEFINE_TRACE_FN(name, reg, unreg)                               \
 122         static const char __tpstrtab_##name[]                           \
 123         __attribute__((section("__tracepoints_strings"))) = #name;      \
 124         struct tracepoint __tracepoint_##name                           \
 125         __attribute__((section("__tracepoints"))) =                     \
 126                 { __tpstrtab_##name, 0, NULL };                         \
 127         static struct tracepoint * const __tracepoint_ptr_##name        \
 128         __attribute__((used, section("__tracepoints_ptrs"))) =          \
 129                 &__tracepoint_##name;
 130
 131 #define DEFINE_TRACE(name)                                              \
 132         DEFINE_TRACE_FN(name, NULL, NULL)
 133
 134 extern void tracepoint_update_probe_range(struct tracepoint * const *begin,
 135         struct tracepoint * const *end);
 136
 137 #else /* !CONFIG_TRACEPOINTS */
 138 #define __DECLARE_TRACE(name, proto, args)                              \
 139         static inline void trace_##name(proto)                          \
 140         { }                                                             \
 141         static inline void _trace_##name(proto)                         \
 142         { }                                                             \
 143         static inline int __register_trace_##name(void (*probe)(proto), void *data)     \
 144         {                                                               \
 145                 return -ENOSYS;                                         \
 146         }                                                               \
 147         static inline int __unregister_trace_##name(void (*probe)(proto), void *data)   \
 148         {                                                               \
 149                 return -ENOSYS;                                         \
 150         }
 151
 152 #define DEFINE_TRACE(name)
 153 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 154 #define EXPORT_TRACEPOINT_SYMBOL(name)
 155
 156 static inline void tracepoint_update_probe_range(struct tracepoint *begin,
 157         struct tracepoint *end)
 158 { }
 159 #endif /* CONFIG_TRACEPOINTS */
 160
 161 /*
 162  * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
 163  * (void). "void" is a special value in a function prototype and can
 164  * not be combined with other arguments. Since the DECLARE_TRACE()
 165  * macro adds a data element at the beginning of the prototype,
 166  * we need a way to differentiate "(void *data, proto)" from
 167  * "(void *data, void)". The second prototype is invalid.
 168  *
 169  * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
 170  * and "void *__data" as the callback prototype.
 171  *
 172  * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
 173  * "void *__data, proto" as the callback prototype.
 174  */
 175 #define DECLARE_TRACE_NOARGS(name)                                      \
 176                 __DECLARE_TRACE(name, void, , void *__data, __data)
 177
 178 #define DECLARE_TRACE(name, proto, args)                                \
 179                 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),      \
 180                                 PARAMS(void *__data, proto),            \
 181                                 PARAMS(__data, args))
 182
 183 /*
 184  * Connect a probe to a tracepoint.
 185  * Internal API, should not be used directly.
 186  */
 187 extern int tracepoint_probe_register(const char *name, void *probe, void *data);
 188
 189 /*
 190  * Disconnect a probe from a tracepoint.
 191  * Internal API, should not be used directly.
 192  */
 193 extern int tracepoint_probe_unregister(const char *name, void *probe, void *data);
 194
 195 extern int tracepoint_probe_register_noupdate(const char *name, void *probe,
 196                                               void *data);
 197 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
 198                                                 void *data);
 199 extern void tracepoint_probe_update_all(void);
 200
 201 struct tracepoint_iter {
 202 //ust// struct module *module;
 203         struct tracepoint_lib *lib;
 204         struct tracepoint * const *tracepoint;
 205 };
 206
 207 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
 208 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
 209 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
 210 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
 211 extern int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
 212         struct tracepoint * const *begin, struct tracepoint * const *end);
 213
 214 /*
 215  * tracepoint_synchronize_unregister must be called between the last tracepoint
 216  * probe unregistration and the end of module exit to make sure there is no
 217  * caller executing a probe when it is freed.
 218  */
 219 static inline void tracepoint_synchronize_unregister(void)
 220 {
 221 //ust// synchronize_sched();
 222 }
 223
 224 struct tracepoint_lib {
 225         struct tracepoint * const *tracepoints_start;
 226         int tracepoints_count;
 227         struct cds_list_head list;
 228 };
 229
 230 extern int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
 231                                    int tracepoints_count);
 232 extern int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start);
 233
 234 #define TRACEPOINT_LIB                                                  \
 235         extern struct tracepoint * const __start___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \
 236         extern struct tracepoint * const __stop___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \
 237         static struct tracepoint * const __tracepoint_ptr_dummy         \
 238         __attribute__((used, section("__tracepoints_ptrs"))) = NULL;    \
 239         static void __attribute__((constructor)) __tracepoints__init(void)      \
 240         {                                                                       \
 241                 tracepoint_register_lib(__start___tracepoints_ptrs,                     \
 242                                         __stop___tracepoints_ptrs -                     \
 243                                         __start___tracepoints_ptrs);                    \
 244         }                                                                       \
 245                                                                                 \
 246         static void __attribute__((destructor)) __tracepoints__destroy(void)    \
 247         {                                                                       \
 248                 tracepoint_unregister_lib(__start___tracepoints_ptrs);          \
 249         }
 250
 251
 252 #ifndef TRACE_EVENT
 253 /*
 254  * For use with the TRACE_EVENT macro:
 255  *
 256  * We define a tracepoint, its arguments, its printf format
 257  * and its 'fast binary record' layout.
 258  *
 259  * Firstly, name your tracepoint via TRACE_EVENT(name : the
 260  * 'subsystem_event' notation is fine.
 261  *
 262  * Think about this whole construct as the
 263  * 'trace_sched_switch() function' from now on.
 264  *
 265  *
 266  *  TRACE_EVENT(sched_switch,
 267  *
 268  *      *
 269  *      * A function has a regular function arguments
 270  *      * prototype, declare it via TP_PROTO():
 271  *      *
 272  *
 273  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 274  *               struct task_struct *next),
 275  *
 276  *      *
 277  *      * Define the call signature of the 'function'.
 278  *      * (Design sidenote: we use this instead of a
 279  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 280  *      *
 281  *
 282  *      TP_ARGS(rq, prev, next),
 283  *
 284  *      *
 285  *      * Fast binary tracing: define the trace record via
 286  *      * TP_STRUCT__entry(). You can think about it like a
 287  *      * regular C structure local variable definition.
 288  *      *
 289  *      * This is how the trace record is structured and will
 290  *      * be saved into the ring buffer. These are the fields
 291  *      * that will be exposed to readers.
 292  *      *
 293  *      * The declared 'local variable' is called '__entry'
 294  *      *
 295  *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
 296  *      *
 297  *      *       pid_t   prev_pid;
 298  *      *
 299  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 300  *      *
 301  *      *       char    prev_comm[TASK_COMM_LEN];
 302  *      *
 303  *
 304  *      TP_STRUCT__entry(
 305  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
 306  *              __field(        pid_t,  prev_pid                        )
 307  *              __field(        int,    prev_prio                       )
 308  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
 309  *              __field(        pid_t,  next_pid                        )
 310  *              __field(        int,    next_prio                       )
 311  *      ),
 312  *
 313  *      *
 314  *      * Assign the entry into the trace record, by embedding
 315  *      * a full C statement block into TP_fast_assign(). You
 316  *      * can refer to the trace record as '__entry' -
 317  *      * otherwise you can put arbitrary C code in here.
 318  *      *
 319  *      * Note: this C code will execute every time a trace event
 320  *      * happens, on an active tracepoint.
 321  *      *
 322  *
 323  *      TP_fast_assign(
 324  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 325  *              __entry->prev_pid       = prev->pid;
 326  *              __entry->prev_prio      = prev->prio;
 327  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 328  *              __entry->next_pid       = next->pid;
 329  *              __entry->next_prio      = next->prio;
 330  *      )
 331  *
 332  *      *
 333  *      * Formatted output of a trace record via TP_printf().
 334  *      * This is how the tracepoint will appear under debugging
 335  *      * of tracepoints.
 336  *      *
 337  *      * (raw-binary tracing wont actually perform this step.)
 338  *      *
 339  *
 340  *      TP_printf("task %s:%d [%d] ==> %s:%d [%d]",
 341  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 342  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
 343  *
 344  * );
 345  *
 346  * This macro construct is thus used for the regular printf format
 347  * tracing setup.
 348  *
 349  * A set of (un)registration functions can be passed to the variant
 350  * TRACE_EVENT_FN to perform any (un)registration work.
 351  */
 352
 353 struct trace_event {
 354         const char *name;
 355         int (*regfunc)(void *data);
 356         int (*unregfunc)(void *data);
 357 };
 358
 359 struct trace_event_lib {
 360         struct trace_event * const *trace_events_start;
 361         int trace_events_count;
 362         struct cds_list_head list;
 363 };
 364
 365 struct trace_event_iter {
 366         struct trace_event_lib *lib;
 367         struct trace_event * const *trace_event;
 368 };
 369
 370 extern void lock_trace_events(void);
 371 extern void unlock_trace_events(void);
 372
 373 extern void trace_event_iter_start(struct trace_event_iter *iter);
 374 extern void trace_event_iter_next(struct trace_event_iter *iter);
 375 extern void trace_event_iter_reset(struct trace_event_iter *iter);
 376
 377 extern int trace_event_get_iter_range(struct trace_event * const **trace_event,
 378                                       struct trace_event * const *begin,
 379                                       struct trace_event * const *end);
 380
 381 extern void trace_event_update_process(void);
 382 extern int is_trace_event_enabled(const char *channel, const char *name);
 383
 384 extern int trace_event_register_lib(struct trace_event * const *start_trace_events,
 385                                     int trace_event_count);
 386
 387 extern int trace_event_unregister_lib(struct trace_event * const *start_trace_events);
 388
 389 #define TRACE_EVENT_LIB                                                 \
 390         extern struct trace_event * const __start___trace_events_ptrs[] \
 391         __attribute__((weak, visibility("hidden")));                    \
 392         extern struct trace_event * const __stop___trace_events_ptrs[]  \
 393         __attribute__((weak, visibility("hidden")));                    \
 394         static struct trace_event * const __event_ptrs_dummy            \
 395         __attribute__((used, section("__trace_events_ptrs"))) = NULL;   \
 396         static void __attribute__((constructor))                        \
 397         __trace_events__init(void)                                      \
 398         {                                                               \
 399                 trace_event_register_lib(__start___trace_events_ptrs,   \
 400                                          __stop___trace_events_ptrs -   \
 401                                          __start___trace_events_ptrs);  \
 402         }                                                               \
 403                                                                         \
 404         static void __attribute__((destructor))                         \
 405         __trace_event__destroy(void)                                    \
 406         {                                                               \
 407                 trace_event_unregister_lib(__start___trace_events_ptrs);\
 408         }
 409
 410 #define DECLARE_TRACE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
 411 #define DEFINE_TRACE_EVENT(template, name, proto, args)         \
 412         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 413 #define DEFINE_TRACE_EVENT_PRINT(template, name, proto, args, print)    \
 414         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 415
 416 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
 417         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 418 #define TRACE_EVENT_FN(name, proto, args, struct,               \
 419                 assign, print, reg, unreg)                      \
 420         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 421
 422 #endif /* ifdef TRACE_EVENT (see note above) */
 423
 424
 425 #endif /* _UST_TRACEPOINT_H */