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