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