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