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