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