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/immediate.h>
  31 #include <ust/core.h>
  32
  33 struct module;
  34 struct tracepoint;
  35
  36 struct probe {
  37         void *func;
  38         void *data;
  39 };
  40
  41 struct tracepoint {
  42         const char *name;               /* Tracepoint name */
  43         DEFINE_IMV(char, state);        /* State. */
  44         struct probe *probes;
  45 };
  46
  47 #define PARAMS(args...) args
  48
  49 #define TP_PROTO(args...)       args
  50 #define TP_ARGS(args...)        args
  51
  52 /*
  53  * Tracepoints should be added to the instrumented code using the
  54  * "tracepoint()" macro.
  55  */
  56 #define tracepoint(name, args...)       __trace_##name(args)
  57
  58 #define register_tracepoint(name, probe, data)                  \
  59                 __register_trace_##name(probe, data)
  60
  61 #define unregister_tracepoint(name, probe, data)                \
  62                 __unregister_trace_##name(probe, data)
  63
  64 #define CONFIG_TRACEPOINTS
  65 #ifdef CONFIG_TRACEPOINTS
  66
  67 /*
  68  * it_func[0] is never NULL because there is at least one element in the array
  69  * when the array itself is non NULL.
  70  */
  71 #define __DO_TRACE(tp, proto, args)                                     \
  72         do {                                                            \
  73                 struct probe *it_probe_ptr;                             \
  74                 void *it_func;                                          \
  75                 void *__data;                                           \
  76                                                                         \
  77                 rcu_read_lock();                                        \
  78                 it_probe_ptr = rcu_dereference((tp)->probes);           \
  79                 if (it_probe_ptr) {                                     \
  80                         do {                                            \
  81                                 it_func = (it_probe_ptr)->func;         \
  82                                 __data = (it_probe_ptr)->data;          \
  83                                 ((void(*)(proto))(it_func))(args);      \
  84                         } while ((++it_probe_ptr)->func);               \
  85                 }                                                       \
  86                 rcu_read_unlock();                                      \
  87         } while (0)
  88
  89 #define __CHECK_TRACE(name, generic, proto, args)                       \
  90         do {                                                            \
  91                 if (!generic) {                                         \
  92                         if (unlikely(imv_read(__tracepoint_##name.state))) \
  93                                 __DO_TRACE(&__tracepoint_##name,        \
  94                                         TP_PROTO(proto), TP_ARGS(args));        \
  95                 } else {                                                \
  96                         if (unlikely(_imv_read(__tracepoint_##name.state))) \
  97                                 __DO_TRACE(&__tracepoint_##name,        \
  98                                         TP_PROTO(proto), TP_ARGS(args));        \
  99                 }                                                       \
 100         } while (0)
 101
 102 /*
 103  * Make sure the alignment of the structure in the __tracepoints section will
 104  * not add unwanted padding between the beginning of the section and the
 105  * structure. Force alignment to the same alignment as the section start.
 106  *
 107  * The "generic" argument, passed to the declared __trace_##name inline
 108  * function controls which tracepoint enabling mechanism must be used.
 109  * If generic is true, a variable read is used.
 110  * If generic is false, immediate values are used.
 111  */
 112 #define __DECLARE_TRACE(name, proto, args, data_proto, data_args)       \
 113         extern struct tracepoint __tracepoint_##name;                   \
 114         static inline void __trace_##name(proto)                        \
 115         {                                                               \
 116                 __CHECK_TRACE(name, 0, TP_PROTO(data_proto),            \
 117                               TP_ARGS(data_args));                      \
 118         }                                                               \
 119         static inline void _trace_##name(proto)                         \
 120         {                                                               \
 121                 __CHECK_TRACE(name, 1, TP_PROTO(data_proto),            \
 122                               TP_ARGS(data_args));                      \
 123         }                                                               \
 124         static inline int                                               \
 125         __register_trace_##name(void (*probe)(data_proto), void *data)  \
 126         {                                                               \
 127                 return tracepoint_probe_register(#name, (void *)probe,  \
 128                                                  data);                 \
 129                                                                         \
 130         }                                                               \
 131         static inline int                                               \
 132         __unregister_trace_##name(void (*probe)(data_proto), void *data)\
 133         {                                                               \
 134                 return tracepoint_probe_unregister(#name, (void *)probe, \
 135                                                    data);               \
 136         }
 137
 138 #define DEFINE_TRACE_FN(name, reg, unreg)                               \
 139         static const char __tpstrtab_##name[]                           \
 140         __attribute__((section("__tracepoints_strings"))) = #name;      \
 141         struct tracepoint __tracepoint_##name                           \
 142         __attribute__((section("__tracepoints"))) =                     \
 143                 { __tpstrtab_##name, 0, NULL };                         \
 144         static struct tracepoint * const __tracepoint_ptr_##name        \
 145         __attribute__((used, section("__tracepoints_ptrs"))) =          \
 146                 &__tracepoint_##name;
 147
 148 #define DEFINE_TRACE(name)                                              \
 149         DEFINE_TRACE_FN(name, NULL, NULL)
 150
 151 extern void tracepoint_update_probe_range(struct tracepoint * const *begin,
 152         struct tracepoint * const *end);
 153
 154 #else /* !CONFIG_TRACEPOINTS */
 155 #define __DECLARE_TRACE(name, proto, args)                              \
 156         static inline void trace_##name(proto)                          \
 157         { }                                                             \
 158         static inline void _trace_##name(proto)                         \
 159         { }                                                             \
 160         static inline int __register_trace_##name(void (*probe)(proto), void *data)     \
 161         {                                                               \
 162                 return -ENOSYS;                                         \
 163         }                                                               \
 164         static inline int __unregister_trace_##name(void (*probe)(proto), void *data)   \
 165         {                                                               \
 166                 return -ENOSYS;                                         \
 167         }
 168
 169 #define DEFINE_TRACE(name)
 170 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 171 #define EXPORT_TRACEPOINT_SYMBOL(name)
 172
 173 static inline void tracepoint_update_probe_range(struct tracepoint *begin,
 174         struct tracepoint *end)
 175 { }
 176 #endif /* CONFIG_TRACEPOINTS */
 177
 178 /*
 179  * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
 180  * (void). "void" is a special value in a function prototype and can
 181  * not be combined with other arguments. Since the DECLARE_TRACE()
 182  * macro adds a data element at the beginning of the prototype,
 183  * we need a way to differentiate "(void *data, proto)" from
 184  * "(void *data, void)". The second prototype is invalid.
 185  *
 186  * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
 187  * and "void *__data" as the callback prototype.
 188  *
 189  * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
 190  * "void *__data, proto" as the callback prototype.
 191  */
 192 #define DECLARE_TRACE_NOARGS(name)                                      \
 193                 __DECLARE_TRACE(name, void, , void *__data, __data)
 194
 195 #define DECLARE_TRACE(name, proto, args)                                \
 196                 __DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),      \
 197                                 PARAMS(void *__data, proto),            \
 198                                 PARAMS(__data, args))
 199
 200 /*
 201  * Connect a probe to a tracepoint.
 202  * Internal API, should not be used directly.
 203  */
 204 extern int tracepoint_probe_register(const char *name, void *probe, void *data);
 205
 206 /*
 207  * Disconnect a probe from a tracepoint.
 208  * Internal API, should not be used directly.
 209  */
 210 extern int tracepoint_probe_unregister(const char *name, void *probe, void *data);
 211
 212 extern int tracepoint_probe_register_noupdate(const char *name, void *probe,
 213                                               void *data);
 214 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
 215                                                 void *data);
 216 extern void tracepoint_probe_update_all(void);
 217
 218 struct tracepoint_iter {
 219 //ust// struct module *module;
 220         struct tracepoint_lib *lib;
 221         struct tracepoint * const *tracepoint;
 222 };
 223
 224 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
 225 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
 226 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
 227 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
 228 extern int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
 229         struct tracepoint * const *begin, struct tracepoint * const *end);
 230
 231 /*
 232  * tracepoint_synchronize_unregister must be called between the last tracepoint
 233  * probe unregistration and the end of module exit to make sure there is no
 234  * caller executing a probe when it is freed.
 235  */
 236 static inline void tracepoint_synchronize_unregister(void)
 237 {
 238 //ust// synchronize_sched();
 239 }
 240
 241 struct tracepoint_lib {
 242         struct tracepoint * const *tracepoints_start;
 243         int tracepoints_count;
 244         struct cds_list_head list;
 245 };
 246
 247 extern int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
 248                                    int tracepoints_count);
 249 extern int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start);
 250
 251 #define TRACEPOINT_LIB                                                  \
 252         extern struct tracepoint * const __start___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \
 253         extern struct tracepoint * const __stop___tracepoints_ptrs[] __attribute__((weak, visibility("hidden"))); \
 254         static struct tracepoint * const __tracepoint_ptr_dummy         \
 255         __attribute__((used, section("__tracepoints_ptrs"))) = NULL;    \
 256         static void __attribute__((constructor)) __tracepoints__init(void)      \
 257         {                                                                       \
 258                 tracepoint_register_lib(__start___tracepoints_ptrs,                     \
 259                                         __stop___tracepoints_ptrs -                     \
 260                                         __start___tracepoints_ptrs);                    \
 261         }                                                                       \
 262                                                                                 \
 263         static void __attribute__((destructor)) __tracepoints__destroy(void)    \
 264         {                                                                       \
 265                 tracepoint_unregister_lib(__start___tracepoints_ptrs);          \
 266         }
 267
 268
 269 #ifndef TRACE_EVENT
 270 /*
 271  * For use with the TRACE_EVENT macro:
 272  *
 273  * We define a tracepoint, its arguments, its printf format
 274  * and its 'fast binary record' layout.
 275  *
 276  * Firstly, name your tracepoint via TRACE_EVENT(name : the
 277  * 'subsystem_event' notation is fine.
 278  *
 279  * Think about this whole construct as the
 280  * 'trace_sched_switch() function' from now on.
 281  *
 282  *
 283  *  TRACE_EVENT(sched_switch,
 284  *
 285  *      *
 286  *      * A function has a regular function arguments
 287  *      * prototype, declare it via TP_PROTO():
 288  *      *
 289  *
 290  *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 291  *               struct task_struct *next),
 292  *
 293  *      *
 294  *      * Define the call signature of the 'function'.
 295  *      * (Design sidenote: we use this instead of a
 296  *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 297  *      *
 298  *
 299  *      TP_ARGS(rq, prev, next),
 300  *
 301  *      *
 302  *      * Fast binary tracing: define the trace record via
 303  *      * TP_STRUCT__entry(). You can think about it like a
 304  *      * regular C structure local variable definition.
 305  *      *
 306  *      * This is how the trace record is structured and will
 307  *      * be saved into the ring buffer. These are the fields
 308  *      * that will be exposed to readers.
 309  *      *
 310  *      * The declared 'local variable' is called '__entry'
 311  *      *
 312  *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
 313  *      *
 314  *      *       pid_t   prev_pid;
 315  *      *
 316  *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 317  *      *
 318  *      *       char    prev_comm[TASK_COMM_LEN];
 319  *      *
 320  *
 321  *      TP_STRUCT__entry(
 322  *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
 323  *              __field(        pid_t,  prev_pid                        )
 324  *              __field(        int,    prev_prio                       )
 325  *              __array(        char,   next_comm,      TASK_COMM_LEN   )
 326  *              __field(        pid_t,  next_pid                        )
 327  *              __field(        int,    next_prio                       )
 328  *      ),
 329  *
 330  *      *
 331  *      * Assign the entry into the trace record, by embedding
 332  *      * a full C statement block into TP_fast_assign(). You
 333  *      * can refer to the trace record as '__entry' -
 334  *      * otherwise you can put arbitrary C code in here.
 335  *      *
 336  *      * Note: this C code will execute every time a trace event
 337  *      * happens, on an active tracepoint.
 338  *      *
 339  *
 340  *      TP_fast_assign(
 341  *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 342  *              __entry->prev_pid       = prev->pid;
 343  *              __entry->prev_prio      = prev->prio;
 344  *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 345  *              __entry->next_pid       = next->pid;
 346  *              __entry->next_prio      = next->prio;
 347  *      )
 348  *
 349  *      *
 350  *      * Formatted output of a trace record via TP_printf().
 351  *      * This is how the tracepoint will appear under debugging
 352  *      * of tracepoints.
 353  *      *
 354  *      * (raw-binary tracing wont actually perform this step.)
 355  *      *
 356  *
 357  *      TP_printf("task %s:%d [%d] ==> %s:%d [%d]",
 358  *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 359  *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
 360  *
 361  * );
 362  *
 363  * This macro construct is thus used for the regular printf format
 364  * tracing setup.
 365  *
 366  * A set of (un)registration functions can be passed to the variant
 367  * TRACE_EVENT_FN to perform any (un)registration work.
 368  */
 369
 370 struct trace_event {
 371         const char *name;
 372         int (*regfunc)(void *data);
 373         int (*unregfunc)(void *data);
 374 };
 375
 376 struct trace_event_lib {
 377         struct trace_event * const *trace_events_start;
 378         int trace_events_count;
 379         struct cds_list_head list;
 380 };
 381
 382 struct trace_event_iter {
 383         struct trace_event_lib *lib;
 384         struct trace_event * const *trace_event;
 385 };
 386
 387 extern void lock_trace_events(void);
 388 extern void unlock_trace_events(void);
 389
 390 extern void trace_event_iter_start(struct trace_event_iter *iter);
 391 extern void trace_event_iter_next(struct trace_event_iter *iter);
 392 extern void trace_event_iter_reset(struct trace_event_iter *iter);
 393
 394 extern int trace_event_get_iter_range(struct trace_event * const **trace_event,
 395                                       struct trace_event * const *begin,
 396                                       struct trace_event * const *end);
 397
 398 extern void trace_event_update_process(void);
 399 extern int is_trace_event_enabled(const char *channel, const char *name);
 400
 401 extern int trace_event_register_lib(struct trace_event * const *start_trace_events,
 402                                     int trace_event_count);
 403
 404 extern int trace_event_unregister_lib(struct trace_event * const *start_trace_events);
 405
 406 #define TRACE_EVENT_LIB                                                 \
 407         extern struct trace_event * const __start___trace_events_ptrs[] \
 408         __attribute__((weak, visibility("hidden")));                    \
 409         extern struct trace_event * const __stop___trace_events_ptrs[]  \
 410         __attribute__((weak, visibility("hidden")));                    \
 411         static struct trace_event * const __event_ptrs_dummy            \
 412         __attribute__((used, section("__trace_events_ptrs"))) = NULL;   \
 413         static void __attribute__((constructor))                        \
 414         __trace_events__init(void)                                      \
 415         {                                                               \
 416                 trace_event_register_lib(__start___trace_events_ptrs,   \
 417                                          __stop___trace_events_ptrs -   \
 418                                          __start___trace_events_ptrs);  \
 419         }                                                               \
 420                                                                         \
 421         static void __attribute__((destructor))                         \
 422         __trace_event__destroy(void)                                    \
 423         {                                                               \
 424                 trace_event_unregister_lib(__start___trace_events_ptrs);\
 425         }
 426
 427 #define DECLARE_TRACE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
 428 #define DEFINE_TRACE_EVENT(template, name, proto, args)         \
 429         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 430 #define DEFINE_TRACE_EVENT_PRINT(template, name, proto, args, print)    \
 431         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 432
 433 #define TRACE_EVENT(name, proto, args, struct, assign, print)   \
 434         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 435 #define TRACE_EVENT_FN(name, proto, args, struct,               \
 436                 assign, print, reg, unreg)                      \
 437         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 438
 439 #endif /* ifdef TRACE_EVENT (see note above) */
 440
 441
 442 #endif /* _UST_TRACEPOINT_H */