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         LTTNG_EVENT_NOOP,
  69         LTTNG_EVENT_SYSCALLS,
  70 };
  71
  72 /*
  73  * LTTng consumer mode
  74  */
  75 enum lttng_event_output {
  76         LTTNG_EVENT_SPLICE = 0,
  77         LTTNG_EVENT_MMAP   = 1,
  78 };
  79
  80 /* Event context possible type */
  81 enum lttng_event_context_type {
  82         LTTNG_EVENT_CONTEXT_PID                = 0,
  83         LTTNG_EVENT_CONTEXT_PERF_COUNTER       = 1,
  84         LTTNG_EVENT_CONTEXT_COMM               = 2,
  85         LTTNG_EVENT_CONTEXT_PRIO               = 3,
  86         LTTNG_EVENT_CONTEXT_NICE               = 4,
  87         LTTNG_EVENT_CONTEXT_VPID               = 5,
  88         LTTNG_EVENT_CONTEXT_TID                = 6,
  89         LTTNG_EVENT_CONTEXT_VTID               = 7,
  90         LTTNG_EVENT_CONTEXT_PPID               = 8,
  91         LTTNG_EVENT_CONTEXT_VPPID              = 9,
  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         enum lttng_event_type type;
 146         uint32_t enabled;
 147         /* Per event type configuration */
 148         union {
 149                 struct lttng_event_probe_attr probe;
 150                 struct lttng_event_function_attr ftrace;
 151         } attr;
 152 };
 153
 154 /*
 155  * Tracer channel attributes. For both kernel and user-space.
 156  */
 157 struct lttng_channel_attr {
 158         int overwrite;                      /* 1: overwrite, 0: discard */
 159         uint64_t subbuf_size;               /* bytes */
 160         uint64_t num_subbuf;                /* power of 2 */
 161         unsigned int switch_timer_interval; /* usec */
 162         unsigned int read_timer_interval;   /* usec */
 163         enum lttng_event_output output;     /* splice, mmap */
 164 };
 165
 166 /*
 167  * Channel information structure. For both kernel and user-space.
 168  */
 169 struct lttng_channel {
 170         char name[NAME_MAX];
 171         uint32_t enabled;
 172         struct lttng_channel_attr attr;
 173 };
 174
 175 struct lttng_calibrate {
 176         enum lttng_calibrate_type type;
 177 };
 178
 179 /*
 180  * Basic session information.
 181  *
 182  * This is an 'output data' meaning that it only comes *from* the session
 183  * daemon *to* the lttng client. It's basically a 'human' representation of
 184  * tracing entities (here a session).
 185  */
 186 struct lttng_session {
 187         char name[NAME_MAX];
 188         /* The path where traces are written */
 189         char path[PATH_MAX];
 190 };
 191
 192 /*
 193  * Handle used as a context for commands.
 194  */
 195 struct lttng_handle {
 196         char session_name[NAME_MAX];
 197         struct lttng_domain domain;
 198 };
 199
 200 /*
 201  * Public LTTng control API
 202  *
 203  * For functions having a lttng domain type as parameter, if a bad value is
 204  * given, NO default is applied and an error is returned.
 205  *
 206  * On success, all functions of the API return 0 or the size of the allocated
 207  * array.
 208  *
 209  * On error, a negative value is returned being a specific lttng-tools error
 210  * code which can be humanly interpreted with lttng_get_readable_code(err).
 211  */
 212
 213 /*
 214  * Create an handle used as a context for every request made to the library.
 215  *
 216  * This handle contains the session name and lttng domain on which the command
 217  * will be executed on.
 218  */
 219 extern struct lttng_handle *lttng_create_handle(const char *session_name,
 220                 struct lttng_domain *domain);
 221
 222 /*
 223  * Destroy an handle. This will simply free(3) the data pointer returned by
 224  * lttng_create_handle() and rendering it unsuable.
 225  */
 226 extern void lttng_destroy_handle(struct lttng_handle *handle);
 227
 228 /*
 229  * Create tracing session using a name and a path where trace will be written.
 230  */
 231 extern int lttng_create_session(const char *name, const char *path);
 232
 233 /*
 234  * Destroy tracing session.
 235  *
 236  * The session will not be useable anymore, tracing will stopped for all
 237  * registered trace and tracing buffers will be flushed.
 238  */
 239 extern int lttng_destroy_session(struct lttng_handle *handle);
 240
 241 /*
 242  * List all tracing sessions.
 243  *
 244  * Return the size of the "lttng_session" array. Caller must free(3).
 245  */
 246 extern int lttng_list_sessions(struct lttng_session **sessions);
 247
 248 /*
 249  * List registered domain(s) of a session.
 250  *
 251  * Return the size of the "lttng_domain" array. Caller must free(3).
 252  */
 253 extern int lttng_list_domains(struct lttng_handle *handle,
 254                 struct lttng_domain **domains);
 255
 256 /*
 257  * List channel(s) of a session.
 258  *
 259  * Return the size of the "lttng_channel" array. Caller must free(3).
 260  */
 261 extern int lttng_list_channels(struct lttng_handle *handle,
 262                 struct lttng_channel **channels);
 263
 264 /*
 265  * List event(s) of a session channel.
 266  *
 267  * Return the size of the "lttng_event" array. Caller must free(3).
 268  */
 269 extern int lttng_list_events(struct lttng_handle *handle,
 270                 const char *channel_name, struct lttng_event **events);
 271
 272 /*
 273  * List available tracepoints of a specific lttng domain.
 274  *
 275  * Return the size of the "lttng_event" array. Caller must free(3).
 276  */
 277 extern int lttng_list_tracepoints(struct lttng_handle *handle,
 278                 struct lttng_event **events);
 279
 280 /*
 281  * Check if a session daemon is alive.
 282  */
 283 extern int lttng_session_daemon_alive(void);
 284
 285 /*
 286  * Set tracing group for the *current* flow of execution.
 287  */
 288 extern int lttng_set_tracing_group(const char *name);
 289
 290 /*
 291  * Return a human readable error message of a lttng-tools error code.
 292  *
 293  * Parameter MUST be a negative value or else you'll get a generic message.
 294  */
 295 extern const char *lttng_get_readable_code(int code);
 296
 297 /*
 298  * This call permits to register an "outside consumer" to a session and a lttng
 299  * domain. No consumer will be spawned and all fds/commands will go through the
 300  * socket path given (socket_path).
 301  *
 302  * NOTE: At the moment, if you use the liblttngkconsumerd, you can only use the
 303  * command socket. The error socket is not supported yet for roaming consumers.
 304  */
 305 extern int lttng_register_consumer(struct lttng_handle *handle,
 306                 const char *socket_path);
 307
 308 /*
 309  * Start tracing for *all* registered trace (kernel and user-space).
 310  */
 311 extern int lttng_start_tracing(struct lttng_handle *handle);
 312
 313 /*
 314  * Stop tracing for *all* registered trace (kernel and user-space).
 315  */
 316 extern int lttng_stop_tracing(struct lttng_handle *handle);
 317
 318 /*
 319  * Add context to event for a specific channel.
 320  *
 321  * If event_name is NULL, the context is applied to all event of the channel.
 322  * If channel_name is NULL, a lookup of the event's channel is done.
 323  * If both are NULL, the context is applied on all events of all channels.
 324  */
 325 extern int lttng_add_context(struct lttng_handle *handle,
 326                 struct lttng_event_context *ctx, const char *event_name,
 327                 const char *channel_name);
 328
 329 /*
 330  * Create or enable a kernel event.
 331  *
 332  * If the event you are trying to enable does not exist, it will be created,
 333  * else it is enabled.
 334  *
 335  * If channel_name is NULL, the default channel is used (channel0).
 336  */
 337 extern int lttng_enable_event(struct lttng_handle *handle,
 338                 struct lttng_event *ev, const char *channel_name);
 339
 340 /*
 341  * Create or enable a kernel channel.
 342  *
 343  * If name is NULL, the default channel is enabled (channel0).
 344  */
 345 extern int lttng_enable_channel(struct lttng_handle *handle,
 346                 struct lttng_channel *chan);
 347
 348 /*
 349  * Disable kernel event.
 350  *
 351  * If channel_name is NULL, the default channel is used (channel0).
 352  */
 353 extern int lttng_disable_event(struct lttng_handle *handle,
 354                 const char *name, const char *channel_name);
 355
 356 /*
 357  * Disable kernel channel.
 358  *
 359  * If channel_name is NULL, the default channel is disabled (channel0).
 360  */
 361 extern int lttng_disable_channel(struct lttng_handle *handle,
 362                 const char *name);
 363
 364 /*
 365  * Calibrate LTTng overhead.
 366  */
 367 extern int lttng_calibrate(struct lttng_handle *handle,
 368                 struct lttng_calibrate *calibrate);
 369
 370 #endif /* _LTTNG_H */