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  * LGPL-compatible code should include this header with :
   9  *
  10  * #define _LGPL_SOURCE
  11  * #include <lttng.h>
  12  *
  13  * This library is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU Lesser General Public
  15  * License as published by the Free Software Foundation; only
  16  * version 2.1 of the License.
  17  *
  18  * This library is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  21  * Lesser General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public
  24  * License along with this library; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  26  */
  27
  28 #ifndef _LTTNG_H
  29 #define _LTTNG_H
  30
  31 #include <asm/types.h>
  32 #include <sys/types.h>
  33 #include <stdint.h>
  34 #include <limits.h>
  35
  36 /* Default unix group name for tracing. */
  37 #define LTTNG_DEFAULT_TRACING_GROUP "tracing"
  38
  39 /* Environment variable to set session daemon binary path. */
  40 #define LTTNG_SESSIOND_PATH_ENV "LTTNG_SESSIOND_PATH"
  41
  42 /* Default trace output directory name */
  43 #define LTTNG_DEFAULT_TRACE_DIR_NAME "lttng-traces"
  44
  45 /*
  46  * Event symbol length. Copied from LTTng kernel ABI.
  47  */
  48 #define LTTNG_SYMBOL_NAME_LEN 128
  49
  50 /*
  51  * Every lttng_event_* structure both apply to kernel event and user-space
  52  * event.
  53  */
  54
  55 /*
  56  * Domain type are the different possible tracers.
  57  */
  58 enum lttng_domain_type {
  59         LTTNG_DOMAIN_KERNEL,
  60         LTTNG_DOMAIN_UST,
  61         LTTNG_DOMAIN_UST_EXEC_NAME,
  62         LTTNG_DOMAIN_UST_PID,
  63         LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN,
  64 };
  65
  66 struct lttng_domain {
  67         enum lttng_domain_type type;
  68         union {
  69                 pid_t pid;
  70                 char exec_name[NAME_MAX];
  71         } attr;
  72 };
  73
  74 /*
  75  * Instrumentation type of tracing event.
  76  */
  77 enum lttng_event_type {
  78         LTTNG_EVENT_TRACEPOINT,
  79         LTTNG_EVENT_PROBE,
  80         LTTNG_EVENT_FUNCTION,
  81 };
  82
  83 /*
  84  * LTTng consumer mode
  85  */
  86 enum lttng_event_output {
  87         LTTNG_EVENT_SPLICE = 0,
  88         LTTNG_EVENT_MMAP   = 1,
  89 };
  90
  91 /* Event context possible type */
  92 enum lttng_event_context_type {
  93         LTTNG_EVENT_CONTEXT_PID                = 0,
  94         LTTNG_EVENT_CONTEXT_PERF_COUNTER       = 1,
  95         LTTNG_EVENT_CONTEXT_COMM               = 2,
  96         LTTNG_EVENT_CONTEXT_PRIO               = 3,
  97         LTTNG_EVENT_CONTEXT_NICE               = 4,
  98         LTTNG_EVENT_CONTEXT_VPID               = 5,
  99         LTTNG_EVENT_CONTEXT_TID                = 6,
 100         LTTNG_EVENT_CONTEXT_VTID               = 7,
 101         LTTNG_EVENT_CONTEXT_PPID               = 8,
 102         LTTNG_EVENT_CONTEXT_VPPID              = 9,
 103 };
 104
 105 /* Perf counter attributes */
 106 struct lttng_event_perf_counter_ctx {
 107         uint32_t type;
 108         uint64_t config;
 109         char name[LTTNG_SYMBOL_NAME_LEN];
 110 };
 111
 112 /* Event/Channel context */
 113 struct lttng_event_context {
 114         enum lttng_event_context_type ctx;
 115         union {
 116                 struct lttng_event_perf_counter_ctx perf_counter;
 117         } u;
 118 };
 119
 120 /*
 121  * Event probe.
 122  *
 123  * Either addr is used or symbol_name and offset.
 124  */
 125 struct lttng_event_probe_attr {
 126         uint64_t addr;
 127
 128         uint64_t offset;
 129         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 130 };
 131
 132 /*
 133  * Function tracer
 134  */
 135 struct lttng_event_function_attr {
 136         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 137 };
 138
 139 /*
 140  * Generic lttng event
 141  */
 142 struct lttng_event {
 143         char name[LTTNG_SYMBOL_NAME_LEN];
 144         enum lttng_event_type type;
 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         struct lttng_channel_attr attr;
 170 };
 171
 172 /*
 173  * Basic session information.
 174  *
 175  * This is an 'output data' meaning that it only comes *from* the session
 176  * daemon *to* the lttng client. It's basically a 'human' representation of
 177  * tracing entities (here a session).
 178  */
 179 struct lttng_session {
 180         char name[NAME_MAX];
 181         /* The path where traces are written */
 182         char path[PATH_MAX];
 183 };
 184
 185 /*
 186  * Public LTTng control API
 187  *
 188  * For functions having a lttng domain type as parameter, if a bad value is
 189  * given, NO default is applied and an error is returned.
 190  *
 191  * On success, all functions of the API return 0 or the size of the allocated
 192  * array.
 193  *
 194  * On error, a negative value is returned being a specific lttng-tools error
 195  * code which can be humanly interpreted with lttng_get_readable_code(err).
 196  */
 197
 198 /*
 199  * Session daemon control
 200  */
 201
 202 /*
 203  * Create tracing session using a name and a path where trace will be written.
 204  */
 205 extern int lttng_create_session(const char *name, const char *path);
 206
 207 /*
 208  * Destroy tracing session.
 209  *
 210  * The session will not be useable anymore, tracing will stopped for all
 211  * registered trace and tracing buffers will be flushed.
 212  */
 213 extern int lttng_destroy_session(const char *name);
 214
 215 /*
 216  * List tracing sessions.
 217  *
 218  * Return the size of the "lttng_session" array. Caller must free(3) the
 219  * returned data.
 220  */
 221 extern int lttng_list_sessions(struct lttng_session **sessions);
 222
 223 /*
 224  * Check if a session daemon is alive.
 225  */
 226 extern int lttng_session_daemon_alive(void);
 227
 228 /*
 229  * Set tracing group for the *current* flow of execution.
 230  */
 231 extern int lttng_set_tracing_group(const char *name);
 232
 233 /*
 234  * Set the session name of the *current* flow of execution.
 235  *
 236  * This is a VERY important things to do before doing any tracing actions. If
 237  * it's not done, you'll get an error saying that the session is not found.
 238  * It avoids the use of a session name on every API call.
 239  */
 240 extern void lttng_set_session_name(const char *name);
 241
 242 /*
 243  * Return a human readable error message of a lttng-tools error code.
 244  *
 245  * Parameter MUST be a negative value or else you'll get a generic message.
 246  */
 247 extern const char *lttng_get_readable_code(int code);
 248
 249 /*
 250  * Start tracing for *all* registered trace (kernel and user-space).
 251  */
 252 extern int lttng_start_tracing(const char *session_name);
 253
 254 /*
 255  * Stop tracing for *all* registered trace (kernel and user-space).
 256  */
 257 extern int lttng_stop_tracing(const char *session_name);
 258
 259 /*
 260  * Add context to event for a specific channel.
 261  *
 262  * If event_name is NULL, the context is applied to all event of the channel.
 263  * If channel_name is NULL, a lookup of the event's channel is done.
 264  * If both are NULL, the context is applied on all events of all channels.
 265  */
 266
 267 extern int lttng_add_context(struct lttng_domain *domain,
 268                 struct lttng_event_context *ctx, const char *event_name,
 269                 const char *channel_name);
 270
 271 /*
 272  * Create or enable a kernel event.
 273  *
 274  * If the event you are trying to enable does not exist, it will be created,
 275  * else it is enabled.
 276  *
 277  * If channel_name is NULL, the default channel is used (channel0).
 278  */
 279 extern int lttng_enable_event(struct lttng_domain *domain, struct lttng_event *ev,
 280                 const char *channel_name);
 281
 282 /*
 283  * Create or enable a kernel channel.
 284  *
 285  * If name is NULL, the default channel is enabled (channel0).
 286  */
 287 extern int lttng_enable_channel(struct lttng_domain *domain,
 288                 struct lttng_channel *chan);
 289
 290 /*
 291  * Disable kernel event.
 292  *
 293  * If channel_name is NULL, the default channel is used (channel0).
 294  */
 295 extern int lttng_disable_event(struct lttng_domain *domain, const char *name,
 296                 const char *channel_name);
 297
 298 /*
 299  * Disable kernel channel.
 300  *
 301  * If channel_name is NULL, the default channel is disabled (channel0).
 302  */
 303 extern int lttng_disable_channel(struct lttng_domain *domain,
 304                 const char *name);
 305
 306 /*
 307  * List kernel events.
 308  *
 309  * Return the size of the allocated event list. Caller must free(3) the data.
 310  */
 311 extern int lttng_list_events(struct lttng_domain *domain, char **event_list);
 312
 313 #endif /* _LTTNG_H */