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         LTTNG_EVENT_TRACEPOINT_LOGLEVEL       = 6,
  69 };
  70
  71 /*
  72  * LTTng consumer mode
  73  */
  74 enum lttng_event_output {
  75         LTTNG_EVENT_SPLICE                    = 0,
  76         LTTNG_EVENT_MMAP                      = 1,
  77 };
  78
  79 /* Event context possible type */
  80 enum lttng_event_context_type {
  81         LTTNG_EVENT_CONTEXT_PID               = 0,
  82         LTTNG_EVENT_CONTEXT_PERF_COUNTER      = 1,
  83         LTTNG_EVENT_CONTEXT_PROCNAME          = 2,
  84         LTTNG_EVENT_CONTEXT_PRIO              = 3,
  85         LTTNG_EVENT_CONTEXT_NICE              = 4,
  86         LTTNG_EVENT_CONTEXT_VPID              = 5,
  87         LTTNG_EVENT_CONTEXT_TID               = 6,
  88         LTTNG_EVENT_CONTEXT_VTID              = 7,
  89         LTTNG_EVENT_CONTEXT_PPID              = 8,
  90         LTTNG_EVENT_CONTEXT_VPPID             = 9,
  91         LTTNG_EVENT_CONTEXT_PTHREAD_ID        = 10,
  92 };
  93
  94 enum lttng_calibrate_type {
  95         LTTNG_CALIBRATE_FUNCTION              = 0,
  96 };
  97
  98 struct lttng_domain {
  99         enum lttng_domain_type type;
 100         union {
 101                 pid_t pid;
 102                 char exec_name[NAME_MAX];
 103         } attr;
 104 };
 105
 106 /* Perf counter attributes */
 107 struct lttng_event_perf_counter_ctx {
 108         uint32_t type;
 109         uint64_t config;
 110         char name[LTTNG_SYMBOL_NAME_LEN];
 111 };
 112
 113 /* Event/Channel context */
 114 struct lttng_event_context {
 115         enum lttng_event_context_type ctx;
 116         union {
 117                 struct lttng_event_perf_counter_ctx perf_counter;
 118         } u;
 119 };
 120
 121 /*
 122  * Event probe.
 123  *
 124  * Either addr is used or symbol_name and offset.
 125  */
 126 struct lttng_event_probe_attr {
 127         uint64_t addr;
 128
 129         uint64_t offset;
 130         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 131 };
 132
 133 /*
 134  * Function tracer
 135  */
 136 struct lttng_event_function_attr {
 137         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 138 };
 139
 140 /*
 141  * Generic lttng event
 142  */
 143 struct lttng_event {
 144         char name[LTTNG_SYMBOL_NAME_LEN];
 145         char loglevel[LTTNG_SYMBOL_NAME_LEN];
 146         int64_t loglevel_value;
 147         enum lttng_event_type type;
 148         uint32_t enabled;
 149         pid_t pid;
 150         /* Per event type configuration */
 151         union {
 152                 struct lttng_event_probe_attr probe;
 153                 struct lttng_event_function_attr ftrace;
 154         } attr;
 155 };
 156
 157 /*
 158  * Tracer channel attributes. For both kernel and user-space.
 159  */
 160 struct lttng_channel_attr {
 161         int overwrite;                      /* 1: overwrite, 0: discard */
 162         uint64_t subbuf_size;               /* bytes */
 163         uint64_t num_subbuf;                /* power of 2 */
 164         unsigned int switch_timer_interval; /* usec */
 165         unsigned int read_timer_interval;   /* usec */
 166         enum lttng_event_output output;     /* splice, mmap */
 167 };
 168
 169 /*
 170  * Channel information structure. For both kernel and user-space.
 171  */
 172 struct lttng_channel {
 173         char name[LTTNG_SYMBOL_NAME_LEN];
 174         uint32_t enabled;
 175         struct lttng_channel_attr attr;
 176 };
 177
 178 struct lttng_calibrate {
 179         enum lttng_calibrate_type type;
 180 };
 181
 182 /*
 183  * Basic session information.
 184  *
 185  * This is an 'output data' meaning that it only comes *from* the session
 186  * daemon *to* the lttng client. It's basically a 'human' representation of
 187  * tracing entities (here a session).
 188  */
 189 struct lttng_session {
 190         char name[NAME_MAX];
 191         /* The path where traces are written */
 192         char path[PATH_MAX];
 193         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
 194 };
 195
 196 /*
 197  * Handle used as a context for commands.
 198  */
 199 struct lttng_handle {
 200         char session_name[NAME_MAX];
 201         struct lttng_domain domain;
 202 };
 203
 204 /*
 205  * Public LTTng control API
 206  *
 207  * For functions having an lttng domain type as parameter, if a bad value is
 208  * given, NO default is applied and an error is returned.
 209  *
 210  * On success, all functions of the API return 0 or the size of the allocated
 211  * array (in bytes).
 212  *
 213  * On error, a negative value is returned being a specific lttng-tools error
 214  * code which can be humanly interpreted with lttng_strerror(err).
 215  *
 216  * Exceptions to this are noted below.
 217  */
 218
 219 /*
 220  * Create a handle used as a context for every request made to the library.
 221  *
 222  * This handle contains the session name and lttng domain on which the command
 223  * will be executed.
 224  * The returned pointer will be NULL in case of malloc() error.
 225  */
 226 extern struct lttng_handle *lttng_create_handle(const char *session_name,
 227                 struct lttng_domain *domain);
 228
 229 /*
 230  * Destroy a handle. This will simply free(3) the data pointer returned by
 231  * lttng_create_handle(), rendering it unusable.
 232  */
 233 extern void lttng_destroy_handle(struct lttng_handle *handle);
 234
 235 /*
 236  * Create a tracing session using a name and a path where the trace will be
 237  * written.
 238  */
 239 extern int lttng_create_session(const char *name, const char *path);
 240
 241 /*
 242  * Destroy a tracing session.
 243  *
 244  * The session will not be usable anymore, tracing will be stopped for all
 245  * registered traces, and the tracing buffers will be flushed.
 246  */
 247 extern int lttng_destroy_session(const char *name);
 248
 249 /*
 250  * List all the tracing sessions.
 251  *
 252  * Return the size (number of entries) of the "lttng_session" array. Caller
 253  * must free(3).
 254  */
 255 extern int lttng_list_sessions(struct lttng_session **sessions);
 256
 257 /*
 258  * List the registered domain(s) of a session.
 259  *
 260  * Return the size (number of entries) of the "lttng_domain" array. Caller
 261  * must free(3).
 262  */
 263 extern int lttng_list_domains(const char *session_name,
 264                 struct lttng_domain **domains);
 265
 266 /*
 267  * List the channel(s) of a session.
 268  *
 269  * Return the size (number of entries) of the "lttng_channel" array. Caller
 270  * must free(3).
 271  */
 272 extern int lttng_list_channels(struct lttng_handle *handle,
 273                 struct lttng_channel **channels);
 274
 275 /*
 276  * List the event(s) of a session channel.
 277  *
 278  * Return the size (number of entries) of the "lttng_event" array.
 279  * Caller must free(3).
 280  */
 281 extern int lttng_list_events(struct lttng_handle *handle,
 282                 const char *channel_name, struct lttng_event **events);
 283
 284 /*
 285  * List the available tracepoints of a specific lttng domain.
 286  *
 287  * Return the size (number of entries) of the "lttng_event" array.
 288  * Caller must free(3).
 289  */
 290 extern int lttng_list_tracepoints(struct lttng_handle *handle,
 291                 struct lttng_event **events);
 292
 293 /*
 294  * Check if a session daemon is alive.
 295  *
 296  * Return 1 if alive or 0 if not. On error returns a negative value.
 297  */
 298 extern int lttng_session_daemon_alive(void);
 299
 300 /*
 301  * Set the tracing group for the *current* flow of execution.
 302  *
 303  * On success, returns 0, on error, returns -1 (null name) or -ENOMEM.
 304  */
 305 extern int lttng_set_tracing_group(const char *name);
 306
 307 /*
 308  * Return a human-readable error message for an lttng-tools error code.
 309  *
 310  * Parameter MUST be a negative value or else you'll get a generic message.
 311  */
 312 extern const char *lttng_strerror(int code);
 313
 314 /*
 315  * This call registers an "outside consumer" for a session and an lttng domain.
 316  * No consumer will be spawned and all fds/commands will go through the socket
 317  * path given (socket_path).
 318  *
 319  * NOTE: At the moment, if you use the liblttng-kconsumer, you can only use the
 320  * command socket. The error socket is not supported yet for roaming consumers.
 321  */
 322 extern int lttng_register_consumer(struct lttng_handle *handle,
 323                 const char *socket_path);
 324
 325 /*
 326  * Start tracing for *all* registered traces (kernel and user-space).
 327  */
 328 extern int lttng_start_tracing(const char *session_name);
 329
 330 /*
 331  * Stop tracing for *all* registered traces (kernel and user-space).
 332  */
 333 extern int lttng_stop_tracing(const char *session_name);
 334
 335 /*
 336  * Add context to event(s) for a specific channel (or for all).
 337  *
 338  * If event_name is NULL, the context is applied to all events of the channel.
 339  * If channel_name is NULL, a lookup of the event's channel is done.
 340  * If both are NULL, the context is applied to all events of all channels.
 341  */
 342 extern int lttng_add_context(struct lttng_handle *handle,
 343                 struct lttng_event_context *ctx, const char *event_name,
 344                 const char *channel_name);
 345
 346 /*
 347  * Create or enable a kernel event (or events) for a channel.
 348  *
 349  * If the event you are trying to enable does not exist, it will be created,
 350  * else it is enabled.
 351  * If event_name is NULL, all events are enabled.
 352  * If channel_name is NULL, the default channel is used (channel0).
 353  */
 354 extern int lttng_enable_event(struct lttng_handle *handle,
 355                 struct lttng_event *ev, const char *channel_name);
 356
 357 /*
 358  * Create or enable a kernel channel.
 359  * The channel name cannot be NULL.
 360  */
 361 extern int lttng_enable_channel(struct lttng_handle *handle,
 362                 struct lttng_channel *chan);
 363
 364 /*
 365  * Disable kernel event(s) of a channel and domain.
 366  *
 367  * If event_name is NULL, all events are disabled.
 368  * If channel_name is NULL, the default channel is used (channel0).
 369  */
 370 extern int lttng_disable_event(struct lttng_handle *handle,
 371                 const char *name, const char *channel_name);
 372
 373 /*
 374  * Disable kernel channel.
 375  *
 376  * The channel name cannot be NULL.
 377  */
 378 extern int lttng_disable_channel(struct lttng_handle *handle,
 379                 const char *name);
 380
 381 /*
 382  * Calibrate LTTng overhead.
 383  */
 384 extern int lttng_calibrate(struct lttng_handle *handle,
 385                 struct lttng_calibrate *calibrate);
 386
 387 /*
 388  * Set the default channel attributes for a specific domain and an allocated
 389  * lttng_channel_attr pointer.
 390  *
 391  * If either or both of the arguments are NULL, nothing happens.
 392  */
 393 extern void lttng_channel_set_default_attr(struct lttng_domain *domain,
 394                 struct lttng_channel_attr *attr);
 395
 396 #endif /* _LTTNG_H */