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
  56         /*
  57          * For now, the domains below are not implemented. However, we keep them
  58          * here in order to retain their enum values for future development. Note
  59          * that it is on the roadmap to implement them.
  60          *
  61         LTTNG_DOMAIN_UST_EXEC_NAME            = 3,
  62         LTTNG_DOMAIN_UST_PID                  = 4,
  63         LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN  = 5,
  64         */
  65 };
  66
  67 /*
  68  * Instrumentation type of tracing event.
  69  */
  70 enum lttng_event_type {
  71         LTTNG_EVENT_ALL                       = -1,
  72         LTTNG_EVENT_TRACEPOINT                = 0,
  73         LTTNG_EVENT_PROBE                     = 1,
  74         LTTNG_EVENT_FUNCTION                  = 2,
  75         LTTNG_EVENT_FUNCTION_ENTRY            = 3,
  76         LTTNG_EVENT_NOOP                      = 4,
  77         LTTNG_EVENT_SYSCALL                   = 5,
  78         LTTNG_EVENT_TRACEPOINT_LOGLEVEL       = 6,
  79 };
  80
  81 /*
  82  * LTTng consumer mode
  83  */
  84 enum lttng_event_output {
  85         LTTNG_EVENT_SPLICE                    = 0,
  86         LTTNG_EVENT_MMAP                      = 1,
  87 };
  88
  89 /* Event context possible type */
  90 enum lttng_event_context_type {
  91         LTTNG_EVENT_CONTEXT_PID               = 0,
  92         LTTNG_EVENT_CONTEXT_PERF_COUNTER      = 1,
  93         LTTNG_EVENT_CONTEXT_COMM              = 2,
  94         LTTNG_EVENT_CONTEXT_PRIO              = 3,
  95         LTTNG_EVENT_CONTEXT_NICE              = 4,
  96         LTTNG_EVENT_CONTEXT_VPID              = 5,
  97         LTTNG_EVENT_CONTEXT_TID               = 6,
  98         LTTNG_EVENT_CONTEXT_VTID              = 7,
  99         LTTNG_EVENT_CONTEXT_PPID              = 8,
 100         LTTNG_EVENT_CONTEXT_VPPID             = 9,
 101 };
 102
 103 enum lttng_calibrate_type {
 104         LTTNG_CALIBRATE_FUNCTION              = 0,
 105 };
 106
 107 struct lttng_domain {
 108         enum lttng_domain_type type;
 109         union {
 110                 pid_t pid;
 111                 char exec_name[NAME_MAX];
 112         } attr;
 113 };
 114
 115 /* Perf counter attributes */
 116 struct lttng_event_perf_counter_ctx {
 117         uint32_t type;
 118         uint64_t config;
 119         char name[LTTNG_SYMBOL_NAME_LEN];
 120 };
 121
 122 /* Event/Channel context */
 123 struct lttng_event_context {
 124         enum lttng_event_context_type ctx;
 125         union {
 126                 struct lttng_event_perf_counter_ctx perf_counter;
 127         } u;
 128 };
 129
 130 /*
 131  * Event probe.
 132  *
 133  * Either addr is used or symbol_name and offset.
 134  */
 135 struct lttng_event_probe_attr {
 136         uint64_t addr;
 137
 138         uint64_t offset;
 139         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 140 };
 141
 142 /*
 143  * Function tracer
 144  */
 145 struct lttng_event_function_attr {
 146         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 147 };
 148
 149 /*
 150  * Generic lttng event
 151  */
 152 struct lttng_event {
 153         char name[LTTNG_SYMBOL_NAME_LEN];
 154         char loglevel[LTTNG_SYMBOL_NAME_LEN];
 155         int64_t loglevel_value;
 156         enum lttng_event_type type;
 157         uint32_t enabled;
 158         pid_t pid;
 159         /* Per event type configuration */
 160         union {
 161                 struct lttng_event_probe_attr probe;
 162                 struct lttng_event_function_attr ftrace;
 163         } attr;
 164 };
 165
 166 /*
 167  * Tracer channel attributes. For both kernel and user-space.
 168  */
 169 struct lttng_channel_attr {
 170         int overwrite;                      /* 1: overwrite, 0: discard */
 171         uint64_t subbuf_size;               /* bytes */
 172         uint64_t num_subbuf;                /* power of 2 */
 173         unsigned int switch_timer_interval; /* usec */
 174         unsigned int read_timer_interval;   /* usec */
 175         enum lttng_event_output output;     /* splice, mmap */
 176 };
 177
 178 /*
 179  * Channel information structure. For both kernel and user-space.
 180  */
 181 struct lttng_channel {
 182         char name[LTTNG_SYMBOL_NAME_LEN];
 183         uint32_t enabled;
 184         struct lttng_channel_attr attr;
 185 };
 186
 187 struct lttng_calibrate {
 188         enum lttng_calibrate_type type;
 189 };
 190
 191 /*
 192  * Basic session information.
 193  *
 194  * This is an 'output data' meaning that it only comes *from* the session
 195  * daemon *to* the lttng client. It's basically a 'human' representation of
 196  * tracing entities (here a session).
 197  */
 198 struct lttng_session {
 199         char name[NAME_MAX];
 200         /* The path where traces are written */
 201         char path[PATH_MAX];
 202         uint32_t enabled;       /* enabled/started: 1, disabled/stopped: 0 */
 203 };
 204
 205 /*
 206  * Handle used as a context for commands.
 207  */
 208 struct lttng_handle {
 209         char session_name[NAME_MAX];
 210         struct lttng_domain domain;
 211 };
 212
 213 /*
 214  * Public LTTng control API
 215  *
 216  * For functions having a lttng domain type as parameter, if a bad value is
 217  * given, NO default is applied and an error is returned.
 218  *
 219  * On success, all functions of the API return 0 or the size of the allocated
 220  * array.
 221  *
 222  * On error, a negative value is returned being a specific lttng-tools error
 223  * code which can be humanly interpreted with lttng_strerror(err).
 224  */
 225
 226 /*
 227  * Create an handle used as a context for every request made to the library.
 228  *
 229  * This handle contains the session name and lttng domain on which the command
 230  * will be executed on.
 231  */
 232 extern struct lttng_handle *lttng_create_handle(const char *session_name,
 233                 struct lttng_domain *domain);
 234
 235 /*
 236  * Destroy an handle. This will simply free(3) the data pointer returned by
 237  * lttng_create_handle() and rendering it unsuable.
 238  */
 239 extern void lttng_destroy_handle(struct lttng_handle *handle);
 240
 241 /*
 242  * Create tracing session using a name and a path where trace will be written.
 243  */
 244 extern int lttng_create_session(const char *name, const char *path);
 245
 246 /*
 247  * Destroy tracing session.
 248  *
 249  * The session will not be useable anymore, tracing will stopped for all
 250  * registered trace and tracing buffers will be flushed.
 251  */
 252 extern int lttng_destroy_session(const char *name);
 253
 254 /*
 255  * List all tracing sessions.
 256  *
 257  * Return the size of the "lttng_session" array. Caller must free(3).
 258  */
 259 extern int lttng_list_sessions(struct lttng_session **sessions);
 260
 261 /*
 262  * List registered domain(s) of a session.
 263  *
 264  * Return the size of the "lttng_domain" array. Caller must free(3).
 265  */
 266 extern int lttng_list_domains(const char *session_name,
 267                 struct lttng_domain **domains);
 268
 269 /*
 270  * List channel(s) of a session.
 271  *
 272  * Return the size of the "lttng_channel" array. Caller must free(3).
 273  */
 274 extern int lttng_list_channels(struct lttng_handle *handle,
 275                 struct lttng_channel **channels);
 276
 277 /*
 278  * List event(s) of a session channel.
 279  *
 280  * Return the size of the "lttng_event" array. Caller must free(3).
 281  */
 282 extern int lttng_list_events(struct lttng_handle *handle,
 283                 const char *channel_name, struct lttng_event **events);
 284
 285 /*
 286  * List available tracepoints of a specific lttng domain.
 287  *
 288  * Return the size of the "lttng_event" array. 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 extern int lttng_session_daemon_alive(void);
 297
 298 /*
 299  * Set tracing group for the *current* flow of execution.
 300  */
 301 extern int lttng_set_tracing_group(const char *name);
 302
 303 /*
 304  * Return a human readable error message of a lttng-tools error code.
 305  *
 306  * Parameter MUST be a negative value or else you'll get a generic message.
 307  */
 308 extern const char *lttng_strerror(int code);
 309
 310 /*
 311  * This call permits to register an "outside consumer" to a session and a lttng
 312  * domain. No consumer will be spawned and all fds/commands will go through the
 313  * socket path given (socket_path).
 314  *
 315  * NOTE: At the moment, if you use the liblttng-kconsumer, you can only use the
 316  * command socket. The error socket is not supported yet for roaming consumers.
 317  */
 318 extern int lttng_register_consumer(struct lttng_handle *handle,
 319                 const char *socket_path);
 320
 321 /*
 322  * Start tracing for *all* registered trace (kernel and user-space).
 323  */
 324 extern int lttng_start_tracing(const char *session_name);
 325
 326 /*
 327  * Stop tracing for *all* registered trace (kernel and user-space).
 328  */
 329 extern int lttng_stop_tracing(const char *session_name);
 330
 331 /*
 332  * Add context to event for a specific channel.
 333  *
 334  * If event_name is NULL, the context is applied to all event of the channel.
 335  * If channel_name is NULL, a lookup of the event's channel is done.
 336  * If both are NULL, the context is applied on all events of all channels.
 337  */
 338 extern int lttng_add_context(struct lttng_handle *handle,
 339                 struct lttng_event_context *ctx, const char *event_name,
 340                 const char *channel_name);
 341
 342 /*
 343  * Create or enable a kernel event.
 344  *
 345  * If the event you are trying to enable does not exist, it will be created,
 346  * else it is enabled.
 347  *
 348  * If channel_name is NULL, the default channel is used (channel0).
 349  */
 350 extern int lttng_enable_event(struct lttng_handle *handle,
 351                 struct lttng_event *ev, const char *channel_name);
 352
 353 /*
 354  * Create or enable a kernel channel.
 355  *
 356  * If name is NULL, the default channel is enabled (channel0).
 357  */
 358 extern int lttng_enable_channel(struct lttng_handle *handle,
 359                 struct lttng_channel *chan);
 360
 361 /*
 362  * Disable kernel event.
 363  *
 364  * If channel_name is NULL, the default channel is used (channel0).
 365  */
 366 extern int lttng_disable_event(struct lttng_handle *handle,
 367                 const char *name, const char *channel_name);
 368
 369 /*
 370  * Disable kernel channel.
 371  *
 372  * If channel_name is NULL, the default channel is disabled (channel0).
 373  */
 374 extern int lttng_disable_channel(struct lttng_handle *handle,
 375                 const char *name);
 376
 377 /*
 378  * Calibrate LTTng overhead.
 379  */
 380 extern int lttng_calibrate(struct lttng_handle *handle,
 381                 struct lttng_calibrate *calibrate);
 382
 383 /*
 384  * Set the default channel attributes for a specific domain and an allocated
 385  * lttng_channel_attr pointer.
 386  */
 387 extern void lttng_channel_set_default_attr(struct lttng_domain *domain,
 388                 struct lttng_channel_attr *attr);
 389
 390 #endif /* _LTTNG_H */