include/lttng/lttng.h

   1 /*
   2  * lttng.h
   3  *
   4  * Linux Trace Toolkit Control Library Header File
   5  *
   6  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   7  *
   8  * This library is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by the
  10  * Free Software Foundation; only version 2.1 of the License.
  11  *
  12  * This library is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
  15  * for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public License
  18  * along with this library; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #ifndef _LTTNG_H
  23 #define _LTTNG_H
  24
  25 #include <limits.h>
  26 #include <stdint.h>
  27 #include <sys/types.h>
  28
  29 /*
  30  * Event symbol length. Copied from LTTng kernel ABI.
  31  */
  32 #define LTTNG_SYMBOL_NAME_LEN 256
  33
  34 /*
  35  * Every lttng_event_* structure both apply to kernel event and user-space
  36  * event.
  37  */
  38
  39 /*
  40  * Domain types: the different possible tracers.
  41  */
  42 enum lttng_domain_type {
  43         LTTNG_DOMAIN_KERNEL                   = 1,
  44         LTTNG_DOMAIN_UST                      = 2,
  45
  46         /*
  47          * For now, the domains below are not implemented. However, we keep them
  48          * here in order to retain their enum values for future development. Note
  49          * that it is on the roadmap to implement them.
  50          *
  51         LTTNG_DOMAIN_UST_EXEC_NAME            = 3,
  52         LTTNG_DOMAIN_UST_PID                  = 4,
  53         LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN  = 5,
  54         */
  55 };
  56
  57 /*
  58  * Instrumentation type of tracing event.
  59  */
  60 enum lttng_event_type {
  61         LTTNG_EVENT_ALL                       = -1,
  62         LTTNG_EVENT_TRACEPOINT                = 0,
  63         LTTNG_EVENT_PROBE                     = 1,
  64         LTTNG_EVENT_FUNCTION                  = 2,
  65         LTTNG_EVENT_FUNCTION_ENTRY            = 3,
  66         LTTNG_EVENT_NOOP                      = 4,
  67         LTTNG_EVENT_SYSCALL                   = 5,
  68 };
  69
  70 /*
  71  * Loglevel information.
  72  */
  73 enum lttng_loglevel_type {
  74         LTTNG_EVENT_LOGLEVEL_ALL              = 0,
  75         LTTNG_EVENT_LOGLEVEL_RANGE            = 1,
  76         LTTNG_EVENT_LOGLEVEL_SINGLE           = 2,
  77 };
  78
  79 /*
  80  * LTTng consumer mode
  81  */
  82 enum lttng_event_output {
  83         LTTNG_EVENT_SPLICE                    = 0,
  84         LTTNG_EVENT_MMAP                      = 1,
  85 };
  86
  87 /* Event context possible type */
  88 enum lttng_event_context_type {
  89         LTTNG_EVENT_CONTEXT_PID               = 0,
  90         LTTNG_EVENT_CONTEXT_PERF_COUNTER      = 1,
  91         LTTNG_EVENT_CONTEXT_PROCNAME          = 2,
  92         LTTNG_EVENT_CONTEXT_PRIO              = 3,
  93         LTTNG_EVENT_CONTEXT_NICE              = 4,
  94         LTTNG_EVENT_CONTEXT_VPID              = 5,
  95         LTTNG_EVENT_CONTEXT_TID               = 6,
  96         LTTNG_EVENT_CONTEXT_VTID              = 7,
  97         LTTNG_EVENT_CONTEXT_PPID              = 8,
  98         LTTNG_EVENT_CONTEXT_VPPID             = 9,
  99         LTTNG_EVENT_CONTEXT_PTHREAD_ID        = 10,
 100 };
 101
 102 enum lttng_calibrate_type {
 103         LTTNG_CALIBRATE_FUNCTION              = 0,
 104 };
 105
 106 struct lttng_domain {
 107         enum lttng_domain_type type;
 108         union {
 109                 pid_t pid;
 110                 char exec_name[NAME_MAX];
 111         } attr;
 112 };
 113
 114 /* Perf counter attributes */
 115 struct lttng_event_perf_counter_ctx {
 116         uint32_t type;
 117         uint64_t config;
 118         char name[LTTNG_SYMBOL_NAME_LEN];
 119 };
 120
 121 /* Event/Channel context */
 122 struct lttng_event_context {
 123         enum lttng_event_context_type ctx;
 124         union {
 125                 struct lttng_event_perf_counter_ctx perf_counter;
 126         } u;
 127 };
 128
 129 /*
 130  * Event probe.
 131  *
 132  * Either addr is used or symbol_name and offset.
 133  */
 134 struct lttng_event_probe_attr {
 135         uint64_t addr;
 136
 137         uint64_t offset;
 138         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 139 };
 140
 141 /*
 142  * Function tracer
 143  */
 144 struct lttng_event_function_attr {
 145         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 146 };
 147
 148 /*
 149  * Generic lttng event
 150  */
 151 struct lttng_event {
 152         enum lttng_event_type type;
 153         char name[LTTNG_SYMBOL_NAME_LEN];
 154
 155         enum lttng_loglevel_type loglevel_type;
 156         int loglevel;
 157
 158         uint32_t enabled;
 159         pid_t pid;
 160         /* Per event type configuration */
 161         union {
 162                 struct lttng_event_probe_attr probe;
 163                 struct lttng_event_function_attr ftrace;
 164         } attr;
 165 };
 166
 167 /*
 168  * Tracer channel attributes. For both kernel and user-space.
 169  */
 170 struct lttng_channel_attr {
 171         int overwrite;                      /* 1: overwrite, 0: discard */
 172         uint64_t subbuf_size;               /* bytes */
 173         uint64_t num_subbuf;                /* power of 2 */
 174         unsigned int switch_timer_interval; /* usec */
 175         unsigned int read_timer_interval;   /* usec */
 176         enum lttng_event_output output;     /* splice, mmap */
 177 };
 178
 179 /*
 180  * Channel information structure. For both kernel and user-space.
 181  */
 182 struct lttng_channel {
 183         char name[LTTNG_SYMBOL_NAME_LEN];
 184         uint32_t enabled;
 185         struct lttng_channel_attr attr;
 186 };
 187
 188 struct lttng_calibrate {
 189         enum lttng_calibrate_type type;
 190 };
 191
 192 /*
 193  * Basic session information.
 194  *
 195  * This is an 'output data' meaning that it only comes *from* the session
 196  * daemon *to* the lttng client. It's basically a 'human' representation of
 197  * tracing entities (here a session).
 198  */
 199 struct lttng_session {
 200         char name[NAME_MAX];
 201         /* The path where traces are written */
 202         char path[PATH_MAX];
 203         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
 204 };
 205
 206 /*
 207  * Handle used as a context for commands.
 208  */
 209 struct lttng_handle {
 210         char session_name[NAME_MAX];
 211         struct lttng_domain domain;
 212 };
 213
 214 /*
 215  * Public LTTng control API
 216  *
 217  * For functions having an lttng domain type as parameter, if a bad value is
 218  * given, NO default is applied and an error is returned.
 219  *
 220  * On success, all functions of the API return 0 or the size of the allocated
 221  * array (in bytes).
 222  *
 223  * On error, a negative value is returned being a specific lttng-tools error
 224  * code which can be humanly interpreted with lttng_strerror(err).
 225  *
 226  * Exceptions to this are noted below.
 227  */
 228
 229 /*
 230  * Create a handle used as a context for every request made to the library.
 231  *
 232  * This handle contains the session name and lttng domain on which the command
 233  * will be executed.
 234  * The returned pointer will be NULL in case of malloc() error.
 235  */
 236 extern struct lttng_handle *lttng_create_handle(const char *session_name,
 237                 struct lttng_domain *domain);
 238
 239 /*
 240  * Destroy a handle. This will simply free(3) the data pointer returned by
 241  * lttng_create_handle(), rendering it unusable.
 242  */
 243 extern void lttng_destroy_handle(struct lttng_handle *handle);
 244
 245 /*
 246  * Create a tracing session using a name and a path where the trace will be
 247  * written.
 248  */
 249 extern int lttng_create_session(const char *name, const char *path);
 250
 251 /*
 252  * Destroy a tracing session.
 253  *
 254  * The session will not be usable anymore, tracing will be stopped for all
 255  * registered traces, and the tracing buffers will be flushed.
 256  */
 257 extern int lttng_destroy_session(const char *name);
 258
 259 /*
 260  * List all the tracing sessions.
 261  *
 262  * Return the size (number of entries) of the "lttng_session" array. Caller
 263  * must free(3).
 264  */
 265 extern int lttng_list_sessions(struct lttng_session **sessions);
 266
 267 /*
 268  * List the registered domain(s) of a session.
 269  *
 270  * Return the size (number of entries) of the "lttng_domain" array. Caller
 271  * must free(3).
 272  */
 273 extern int lttng_list_domains(const char *session_name,
 274                 struct lttng_domain **domains);
 275
 276 /*
 277  * List the channel(s) of a session.
 278  *
 279  * Return the size (number of entries) of the "lttng_channel" array. Caller
 280  * must free(3).
 281  */
 282 extern int lttng_list_channels(struct lttng_handle *handle,
 283                 struct lttng_channel **channels);
 284
 285 /*
 286  * List the event(s) of a session channel.
 287  *
 288  * Return the size (number of entries) of the "lttng_event" array.
 289  * Caller must free(3).
 290  */
 291 extern int lttng_list_events(struct lttng_handle *handle,
 292                 const char *channel_name, struct lttng_event **events);
 293
 294 /*
 295  * List the available tracepoints of a specific lttng domain.
 296  *
 297  * Return the size (number of entries) of the "lttng_event" array.
 298  * Caller must free(3).
 299  */
 300 extern int lttng_list_tracepoints(struct lttng_handle *handle,
 301                 struct lttng_event **events);
 302
 303 /*
 304  * Check if a session daemon is alive.
 305  *
 306  * Return 1 if alive or 0 if not. On error returns a negative value.
 307  */
 308 extern int lttng_session_daemon_alive(void);
 309
 310 /*
 311  * Set the tracing group for the *current* flow of execution.
 312  *
 313  * On success, returns 0, on error, returns -1 (null name) or -ENOMEM.
 314  */
 315 extern int lttng_set_tracing_group(const char *name);
 316
 317 /*
 318  * Return a human-readable error message for an lttng-tools error code.
 319  *
 320  * Parameter MUST be a negative value or else you'll get a generic message.
 321  */
 322 extern const char *lttng_strerror(int code);
 323
 324 /*
 325  * This call registers an "outside consumer" for a session and an lttng domain.
 326  * No consumer will be spawned and all fds/commands will go through the socket
 327  * path given (socket_path).
 328  *
 329  * NOTE: At the moment, if you use the liblttng-kconsumer, you can only use the
 330  * command socket. The error socket is not supported yet for roaming consumers.
 331  */
 332 extern int lttng_register_consumer(struct lttng_handle *handle,
 333                 const char *socket_path);
 334
 335 /*
 336  * Start tracing for *all* registered traces (kernel and user-space).
 337  */
 338 extern int lttng_start_tracing(const char *session_name);
 339
 340 /*
 341  * Stop tracing for *all* registered traces (kernel and user-space).
 342  */
 343 extern int lttng_stop_tracing(const char *session_name);
 344
 345 /*
 346  * Add context to event(s) for a specific channel (or for all).
 347  *
 348  * If event_name is NULL, the context is applied to all events of the channel.
 349  * If channel_name is NULL, a lookup of the event's channel is done.
 350  * If both are NULL, the context is applied to all events of all channels.
 351  */
 352 extern int lttng_add_context(struct lttng_handle *handle,
 353                 struct lttng_event_context *ctx, const char *event_name,
 354                 const char *channel_name);
 355
 356 /*
 357  * Create or enable a kernel event (or events) for a channel.
 358  *
 359  * If the event you are trying to enable does not exist, it will be created,
 360  * else it is enabled.
 361  * If event_name is NULL, all events are enabled.
 362  * If channel_name is NULL, the default channel is used (channel0).
 363  */
 364 extern int lttng_enable_event(struct lttng_handle *handle,
 365                 struct lttng_event *ev, const char *channel_name);
 366
 367 /*
 368  * Create or enable a kernel channel.
 369  * The channel name cannot be NULL.
 370  */
 371 extern int lttng_enable_channel(struct lttng_handle *handle,
 372                 struct lttng_channel *chan);
 373
 374 /*
 375  * Disable kernel event(s) of a channel and domain.
 376  *
 377  * If event_name is NULL, all events are disabled.
 378  * If channel_name is NULL, the default channel is used (channel0).
 379  */
 380 extern int lttng_disable_event(struct lttng_handle *handle,
 381                 const char *name, const char *channel_name);
 382
 383 /*
 384  * Disable kernel channel.
 385  *
 386  * The channel name cannot be NULL.
 387  */
 388 extern int lttng_disable_channel(struct lttng_handle *handle,
 389                 const char *name);
 390
 391 /*
 392  * Calibrate LTTng overhead.
 393  */
 394 extern int lttng_calibrate(struct lttng_handle *handle,
 395                 struct lttng_calibrate *calibrate);
 396
 397 /*
 398  * Set the default channel attributes for a specific domain and an allocated
 399  * lttng_channel_attr pointer.
 400  *
 401  * If either or both of the arguments are NULL, nothing happens.
 402  */
 403 extern void lttng_channel_set_default_attr(struct lttng_domain *domain,
 404                 struct lttng_channel_attr *attr);
 405
 406 #endif /* _LTTNG_H */