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 <asm/types.h>
  27 #include <sys/types.h>
  28 #include <stdint.h>
  29 #include <limits.h>
  30
  31 /* Default unix group name for tracing. */
  32 #define LTTNG_DEFAULT_TRACING_GROUP "tracing"
  33
  34 /* Environment variable to set session daemon binary path. */
  35 #define LTTNG_SESSIOND_PATH_ENV "LTTNG_SESSIOND_PATH"
  36
  37 /* Default trace output directory name */
  38 #define LTTNG_DEFAULT_TRACE_DIR_NAME "lttng-traces"
  39
  40 /*
  41  * Event symbol length. Copied from LTTng kernel ABI.
  42  */
  43 #define LTTNG_SYMBOL_NAME_LEN 128
  44
  45 /*
  46  * Every lttng_event_* structure both apply to kernel event and user-space
  47  * event.
  48  */
  49
  50 /*
  51  * Domain type are the different possible tracers.
  52  */
  53 enum lttng_domain_type {
  54         LTTNG_DOMAIN_KERNEL,
  55         LTTNG_DOMAIN_UST,
  56         LTTNG_DOMAIN_UST_EXEC_NAME,
  57         LTTNG_DOMAIN_UST_PID,
  58         LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN,
  59 };
  60
  61 struct lttng_domain {
  62         enum lttng_domain_type type;
  63         union {
  64                 pid_t pid;
  65                 char exec_name[NAME_MAX];
  66         } attr;
  67 };
  68
  69 /*
  70  * Instrumentation type of tracing event.
  71  */
  72 enum lttng_event_type {
  73         LTTNG_EVENT_TRACEPOINT,
  74         LTTNG_EVENT_PROBE,
  75         LTTNG_EVENT_FUNCTION,
  76         LTTNG_EVENT_FUNCTION_ENTRY,
  77 };
  78
  79 /*
  80  * LTTng consumer mode
  81  */
  82 enum lttng_event_output {
  83         LTTNG_EVENT_SPLICE = 0,
  84         LTTNG_EVENT_MMAP   = 1,
  85 };
  86
  87 /* Event context possible type */
  88 enum lttng_event_context_type {
  89         LTTNG_EVENT_CONTEXT_PID                = 0,
  90         LTTNG_EVENT_CONTEXT_PERF_COUNTER       = 1,
  91         LTTNG_EVENT_CONTEXT_COMM               = 2,
  92         LTTNG_EVENT_CONTEXT_PRIO               = 3,
  93         LTTNG_EVENT_CONTEXT_NICE               = 4,
  94         LTTNG_EVENT_CONTEXT_VPID               = 5,
  95         LTTNG_EVENT_CONTEXT_TID                = 6,
  96         LTTNG_EVENT_CONTEXT_VTID               = 7,
  97         LTTNG_EVENT_CONTEXT_PPID               = 8,
  98         LTTNG_EVENT_CONTEXT_VPPID              = 9,
  99 };
 100
 101 /* Perf counter attributes */
 102 struct lttng_event_perf_counter_ctx {
 103         uint32_t type;
 104         uint64_t config;
 105         char name[LTTNG_SYMBOL_NAME_LEN];
 106 };
 107
 108 /* Event/Channel context */
 109 struct lttng_event_context {
 110         enum lttng_event_context_type ctx;
 111         union {
 112                 struct lttng_event_perf_counter_ctx perf_counter;
 113         } u;
 114 };
 115
 116 /*
 117  * Event probe.
 118  *
 119  * Either addr is used or symbol_name and offset.
 120  */
 121 struct lttng_event_probe_attr {
 122         uint64_t addr;
 123
 124         uint64_t offset;
 125         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 126 };
 127
 128 /*
 129  * Function tracer
 130  */
 131 struct lttng_event_function_attr {
 132         char symbol_name[LTTNG_SYMBOL_NAME_LEN];
 133 };
 134
 135 /*
 136  * Generic lttng event
 137  */
 138 struct lttng_event {
 139         char name[LTTNG_SYMBOL_NAME_LEN];
 140         enum lttng_event_type type;
 141         /* Per event type configuration */
 142         union {
 143                 struct lttng_event_probe_attr probe;
 144                 struct lttng_event_function_attr ftrace;
 145         } attr;
 146 };
 147
 148 /*
 149  * Tracer channel attributes. For both kernel and user-space.
 150  */
 151 struct lttng_channel_attr {
 152         int overwrite;                      /* 1: overwrite, 0: discard */
 153         uint64_t subbuf_size;               /* bytes */
 154         uint64_t num_subbuf;                /* power of 2 */
 155         unsigned int switch_timer_interval; /* usec */
 156         unsigned int read_timer_interval;   /* usec */
 157         enum lttng_event_output output;     /* splice, mmap */
 158 };
 159
 160 /*
 161  * Channel information structure. For both kernel and user-space.
 162  */
 163 struct lttng_channel {
 164         char name[NAME_MAX];
 165         struct lttng_channel_attr attr;
 166 };
 167
 168 /*
 169  * Basic session information.
 170  *
 171  * This is an 'output data' meaning that it only comes *from* the session
 172  * daemon *to* the lttng client. It's basically a 'human' representation of
 173  * tracing entities (here a session).
 174  */
 175 struct lttng_session {
 176         char name[NAME_MAX];
 177         /* The path where traces are written */
 178         char path[PATH_MAX];
 179 };
 180
 181 /*
 182  * Public LTTng control API
 183  *
 184  * For functions having a lttng domain type as parameter, if a bad value is
 185  * given, NO default is applied and an error is returned.
 186  *
 187  * On success, all functions of the API return 0 or the size of the allocated
 188  * array.
 189  *
 190  * On error, a negative value is returned being a specific lttng-tools error
 191  * code which can be humanly interpreted with lttng_get_readable_code(err).
 192  */
 193
 194 /*
 195  * Session daemon control
 196  */
 197
 198 /*
 199  * Create tracing session using a name and a path where trace will be written.
 200  */
 201 extern int lttng_create_session(const char *name, const char *path);
 202
 203 /*
 204  * Destroy tracing session.
 205  *
 206  * The session will not be useable anymore, tracing will stopped for all
 207  * registered trace and tracing buffers will be flushed.
 208  */
 209 extern int lttng_destroy_session(const char *name);
 210
 211 /*
 212  * List tracing sessions.
 213  *
 214  * Return the size of the "lttng_session" array. Caller must free(3) the
 215  * returned data.
 216  */
 217 extern int lttng_list_sessions(struct lttng_session **sessions);
 218
 219 /*
 220  * Check if a session daemon is alive.
 221  */
 222 extern int lttng_session_daemon_alive(void);
 223
 224 /*
 225  * Set tracing group for the *current* flow of execution.
 226  */
 227 extern int lttng_set_tracing_group(const char *name);
 228
 229 /*
 230  * Set the session name of the *current* flow of execution.
 231  *
 232  * This is a VERY important things to do before doing any tracing actions. If
 233  * it's not done, you'll get an error saying that the session is not found.
 234  * It avoids the use of a session name on every API call.
 235  */
 236 extern void lttng_set_session_name(const char *name);
 237
 238 /*
 239  * Return a human readable error message of a lttng-tools error code.
 240  *
 241  * Parameter MUST be a negative value or else you'll get a generic message.
 242  */
 243 extern const char *lttng_get_readable_code(int code);
 244
 245 /*
 246  * Start tracing for *all* registered trace (kernel and user-space).
 247  */
 248 extern int lttng_start_tracing(const char *session_name);
 249
 250 /*
 251  * Stop tracing for *all* registered trace (kernel and user-space).
 252  */
 253 extern int lttng_stop_tracing(const char *session_name);
 254
 255 /*
 256  * Add context to event for a specific channel.
 257  *
 258  * If event_name is NULL, the context is applied to all event of the channel.
 259  * If channel_name is NULL, a lookup of the event's channel is done.
 260  * If both are NULL, the context is applied on all events of all channels.
 261  */
 262
 263 extern int lttng_add_context(struct lttng_domain *domain,
 264                 struct lttng_event_context *ctx, const char *event_name,
 265                 const char *channel_name);
 266
 267 /*
 268  * Create or enable a kernel event.
 269  *
 270  * If the event you are trying to enable does not exist, it will be created,
 271  * else it is enabled.
 272  *
 273  * If channel_name is NULL, the default channel is used (channel0).
 274  */
 275 extern int lttng_enable_event(struct lttng_domain *domain, struct lttng_event *ev,
 276                 const char *channel_name);
 277
 278 /*
 279  * Create or enable a kernel channel.
 280  *
 281  * If name is NULL, the default channel is enabled (channel0).
 282  */
 283 extern int lttng_enable_channel(struct lttng_domain *domain,
 284                 struct lttng_channel *chan);
 285
 286 /*
 287  * Disable kernel event.
 288  *
 289  * If channel_name is NULL, the default channel is used (channel0).
 290  */
 291 extern int lttng_disable_event(struct lttng_domain *domain, const char *name,
 292                 const char *channel_name);
 293
 294 /*
 295  * Disable kernel channel.
 296  *
 297  * If channel_name is NULL, the default channel is disabled (channel0).
 298  */
 299 extern int lttng_disable_channel(struct lttng_domain *domain,
 300                 const char *name);
 301
 302 /*
 303  * List kernel events.
 304  *
 305  * Return the size of the allocated event list. Caller must free(3) the data.
 306  */
 307 extern int lttng_list_events(struct lttng_domain *domain, char **event_list);
 308
 309 #endif /* _LTTNG_H */