liblttng-ust/ltt-events.c

   1 /*
   2  * ltt-events.c
   3  *
   4  * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * Holds LTTng per-session event registry.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #define _GNU_SOURCE
  12 #include <stdio.h>
  13 #include <endian.h>
  14 #include <urcu/list.h>
  15 #include <urcu/hlist.h>
  16 #include <pthread.h>
  17 #include <uuid/uuid.h>
  18 #include <errno.h>
  19 #include <sys/shm.h>
  20 #include <sys/ipc.h>
  21 #include <stdint.h>
  22 #include <stddef.h>
  23
  24 #include <urcu-bp.h>
  25 #include <urcu/compiler.h>
  26 #include <urcu/uatomic.h>
  27 #include <urcu/arch.h>
  28
  29 #include <lttng/tracepoint.h>
  30 #include <lttng/ust-events.h>
  31
  32 #include <usterr-signal-safe.h>
  33 #include <helper.h>
  34 #include "error.h"
  35
  36 #include "ltt-tracer.h"
  37 #include "ltt-tracer-core.h"
  38 #include "wait.h"
  39 #include "../libringbuffer/shm.h"
  40 #include "jhash.h"
  41
  42 /*
  43  * The sessions mutex is the centralized mutex across UST tracing
  44  * control and probe registration. All operations within this file are
  45  * called by the communication thread, under ust_lock protection.
  46  */
  47 static pthread_mutex_t sessions_mutex = PTHREAD_MUTEX_INITIALIZER;
  48
  49 void ust_lock(void)
  50 {
  51         pthread_mutex_lock(&sessions_mutex);
  52 }
  53
  54 void ust_unlock(void)
  55 {
  56         pthread_mutex_unlock(&sessions_mutex);
  57 }
  58
  59 static CDS_LIST_HEAD(sessions);
  60
  61 /*
  62  * Pending probes hash table, containing the registered ltt events for
  63  * which tracepoint probes are still missing. Protected by the sessions
  64  * mutex.
  65  */
  66 #define PENDING_PROBE_HASH_BITS         6
  67 #define PENDING_PROBE_HASH_SIZE         (1 << PENDING_PROBE_HASH_BITS)
  68 static struct cds_hlist_head pending_probe_table[PENDING_PROBE_HASH_SIZE];
  69
  70 struct ust_pending_probe {
  71         struct ltt_event *event;
  72         struct cds_hlist_node node;
  73         char name[];
  74 };
  75
  76 static void _ltt_event_destroy(struct ltt_event *event);
  77 static void _ltt_loglevel_destroy(struct session_loglevel *sl);
  78 static void _ltt_wildcard_destroy(struct session_wildcard *sw);
  79 static void _ltt_channel_destroy(struct ltt_channel *chan);
  80 static int _ltt_event_unregister(struct ltt_event *event);
  81 static
  82 int _ltt_event_metadata_statedump(struct ltt_session *session,
  83                                   struct ltt_channel *chan,
  84                                   struct ltt_event *event);
  85 static
  86 int _ltt_session_metadata_statedump(struct ltt_session *session);
  87
  88 /*
  89  * called at event creation if probe is missing.
  90  * called with session mutex held.
  91  */
  92 static
  93 int add_pending_probe(struct ltt_event *event, const char *name)
  94 {
  95         struct cds_hlist_head *head;
  96         struct ust_pending_probe *e;
  97         size_t name_len = strlen(name);
  98         uint32_t hash;
  99
 100         if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
 101                 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
 102                 name_len = LTTNG_UST_SYM_NAME_LEN - 1;
 103         }
 104         hash = jhash(name, name_len, 0);
 105         head = &pending_probe_table[hash & (PENDING_PROBE_HASH_SIZE - 1)];
 106         e = zmalloc(sizeof(struct ust_pending_probe) + name_len);
 107         if (!e)
 108                 return -ENOMEM;
 109         memcpy(&e->name[0], name, name_len + 1);
 110         e->name[name_len] = '\0';
 111         cds_hlist_add_head(&e->node, head);
 112         e->event = event;
 113         event->pending_probe = e;
 114         return 0;
 115 }
 116
 117 /*
 118  * remove a pending probe. called when at event teardown and when an
 119  * event is fixed (probe is loaded).
 120  * called with session mutex held.
 121  */
 122 static
 123 void remove_pending_probe(struct ust_pending_probe *e)
 124 {
 125         if (!e)
 126                 return;
 127         cds_hlist_del(&e->node);
 128         free(e);
 129 }
 130
 131 /*
 132  * Called at library load: connect the probe on the events pending on
 133  * probe load.
 134  * called with session mutex held.
 135  */
 136 int pending_probe_fix_events(const struct lttng_event_desc *desc)
 137 {
 138         struct cds_hlist_head *head;
 139         struct cds_hlist_node *node, *p;
 140         struct ust_pending_probe *e;
 141         const char *name = desc->name;
 142         int ret = 0;
 143         struct lttng_ust_event event_param;
 144         size_t name_len = strlen(name);
 145         uint32_t hash;
 146
 147         /*
 148          * For this event, we need to lookup the loglevel. If active (in
 149          * the active loglevels hash table), we must create the event.
 150          */
 151         if (desc->loglevel) {
 152                 const struct tracepoint_loglevel_entry *ev_ll;
 153                 struct loglevel_entry *loglevel;
 154
 155                 ev_ll = *desc->loglevel;
 156                 loglevel = get_loglevel(ev_ll->identifier);
 157                 if (!loglevel)
 158                         loglevel = get_loglevel_value(ev_ll->value);
 159                 if (loglevel) {
 160                         struct session_loglevel *sl;
 161
 162                         cds_list_for_each_entry(sl, &loglevel->session_list,
 163                                         session_list) {
 164                                 struct ltt_event *ev;
 165                                 int ret;
 166
 167                                 memcpy(&event_param, &sl->event_param,
 168                                                 sizeof(event_param));
 169                                 memcpy(event_param.name,
 170                                         desc->name,
 171                                         sizeof(event_param.name));
 172                                 /* create event */
 173                                 ret = ltt_event_create(sl->chan,
 174                                         &event_param, NULL,
 175                                         &ev);
 176                                 if (ret) {
 177                                         DBG("Error creating event");
 178                                         continue;
 179                                 }
 180                                 cds_list_add(&ev->loglevel_list,
 181                                         &sl->events);
 182                         }
 183                 }
 184         }
 185
 186         /* Wildcard */
 187         {
 188                 struct wildcard_entry *wildcard;
 189
 190                 wildcard = match_wildcard(desc->name);
 191                 if (strcmp(desc->name, "lttng_ust:metadata") && wildcard) {
 192                         struct session_wildcard *sw;
 193
 194                         cds_list_for_each_entry(sw, &wildcard->session_list,
 195                                         session_list) {
 196                                 struct ltt_event *ev;
 197                                 int ret;
 198
 199                                 memcpy(&event_param, &sw->event_param,
 200                                                 sizeof(event_param));
 201                                 memcpy(event_param.name,
 202                                         desc->name,
 203                                         sizeof(event_param.name));
 204                                 /* create event */
 205                                 ret = ltt_event_create(sw->chan,
 206                                         &event_param, NULL,
 207                                         &ev);
 208                                 if (ret) {
 209                                         DBG("Error creating event");
 210                                         continue;
 211                                 }
 212                                 cds_list_add(&ev->wildcard_list,
 213                                         &sw->events);
 214                         }
 215                 }
 216         }
 217
 218         if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
 219                 WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
 220                 name_len = LTTNG_UST_SYM_NAME_LEN - 1;
 221         }
 222         hash = jhash(name, name_len, 0);
 223         head = &pending_probe_table[hash & (PENDING_PROBE_HASH_SIZE - 1)];
 224         cds_hlist_for_each_entry_safe(e, node, p, head, node) {
 225                 struct ltt_event *event;
 226                 struct ltt_channel *chan;
 227
 228                 if (strncmp(name, e->name, LTTNG_UST_SYM_NAME_LEN - 1))
 229                         continue;
 230                 event = e->event;
 231                 chan = event->chan;
 232                 assert(!event->desc);
 233                 event->desc = desc;
 234                 event->pending_probe = NULL;
 235                 remove_pending_probe(e);
 236                 ret |= __tracepoint_probe_register(name,
 237                                 event->desc->probe_callback,
 238                                 event);
 239                 if (ret)
 240                         continue;
 241                 event->id = chan->free_event_id++;
 242                 ret |= _ltt_event_metadata_statedump(chan->session, chan,
 243                                 event);
 244         }
 245         return ret;
 246 }
 247
 248 void synchronize_trace(void)
 249 {
 250         synchronize_rcu();
 251 }
 252
 253 struct ltt_session *ltt_session_create(void)
 254 {
 255         struct ltt_session *session;
 256
 257         session = zmalloc(sizeof(struct ltt_session));
 258         if (!session)
 259                 return NULL;
 260         CDS_INIT_LIST_HEAD(&session->chan);
 261         CDS_INIT_LIST_HEAD(&session->events);
 262         CDS_INIT_LIST_HEAD(&session->loglevels);
 263         CDS_INIT_LIST_HEAD(&session->wildcards);
 264         uuid_generate(session->uuid);
 265         cds_list_add(&session->list, &sessions);
 266         return session;
 267 }
 268
 269 void ltt_session_destroy(struct ltt_session *session)
 270 {
 271         struct ltt_channel *chan, *tmpchan;
 272         struct ltt_event *event, *tmpevent;
 273         struct session_loglevel *loglevel, *tmploglevel;
 274         struct session_wildcard *wildcard, *tmpwildcard;
 275         int ret;
 276
 277         CMM_ACCESS_ONCE(session->active) = 0;
 278         cds_list_for_each_entry(event, &session->events, list) {
 279                 ret = _ltt_event_unregister(event);
 280                 WARN_ON(ret);
 281         }
 282         synchronize_trace();    /* Wait for in-flight events to complete */
 283         cds_list_for_each_entry_safe(loglevel, tmploglevel, &session->loglevels, list)
 284                 _ltt_loglevel_destroy(loglevel);
 285         cds_list_for_each_entry_safe(wildcard, tmpwildcard, &session->wildcards, list)
 286                 _ltt_wildcard_destroy(wildcard);
 287         cds_list_for_each_entry_safe(event, tmpevent, &session->events, list)
 288                 _ltt_event_destroy(event);
 289         cds_list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
 290                 _ltt_channel_destroy(chan);
 291         cds_list_del(&session->list);
 292         free(session);
 293 }
 294
 295 int ltt_session_enable(struct ltt_session *session)
 296 {
 297         int ret = 0;
 298         struct ltt_channel *chan;
 299
 300         if (session->active) {
 301                 ret = -EBUSY;
 302                 goto end;
 303         }
 304
 305         /*
 306          * Snapshot the number of events per channel to know the type of header
 307          * we need to use.
 308          */
 309         cds_list_for_each_entry(chan, &session->chan, list) {
 310                 if (chan->header_type)
 311                         continue;               /* don't change it if session stop/restart */
 312                 if (chan->free_event_id < 31)
 313                         chan->header_type = 1;  /* compact */
 314                 else
 315                         chan->header_type = 2;  /* large */
 316         }
 317
 318         CMM_ACCESS_ONCE(session->active) = 1;
 319         CMM_ACCESS_ONCE(session->been_active) = 1;
 320         ret = _ltt_session_metadata_statedump(session);
 321         if (ret)
 322                 CMM_ACCESS_ONCE(session->active) = 0;
 323 end:
 324         return ret;
 325 }
 326
 327 int ltt_session_disable(struct ltt_session *session)
 328 {
 329         int ret = 0;
 330
 331         if (!session->active) {
 332                 ret = -EBUSY;
 333                 goto end;
 334         }
 335         CMM_ACCESS_ONCE(session->active) = 0;
 336 end:
 337         return ret;
 338 }
 339
 340 int ltt_channel_enable(struct ltt_channel *channel)
 341 {
 342         int old;
 343
 344         if (channel == channel->session->metadata)
 345                 return -EPERM;
 346         old = uatomic_xchg(&channel->enabled, 1);
 347         if (old)
 348                 return -EEXIST;
 349         return 0;
 350 }
 351
 352 int ltt_channel_disable(struct ltt_channel *channel)
 353 {
 354         int old;
 355
 356         if (channel == channel->session->metadata)
 357                 return -EPERM;
 358         old = uatomic_xchg(&channel->enabled, 0);
 359         if (!old)
 360                 return -EEXIST;
 361         return 0;
 362 }
 363
 364 int ltt_event_enable(struct ltt_event *event)
 365 {
 366         int old;
 367
 368         if (event->chan == event->chan->session->metadata)
 369                 return -EPERM;
 370         old = uatomic_xchg(&event->enabled, 1);
 371         if (old)
 372                 return -EEXIST;
 373         return 0;
 374 }
 375
 376 int ltt_event_disable(struct ltt_event *event)
 377 {
 378         int old;
 379
 380         if (event->chan == event->chan->session->metadata)
 381                 return -EPERM;
 382         old = uatomic_xchg(&event->enabled, 0);
 383         if (!old)
 384                 return -EEXIST;
 385         return 0;
 386 }
 387
 388 struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 389                                        const char *transport_name,
 390                                        void *buf_addr,
 391                                        size_t subbuf_size, size_t num_subbuf,
 392                                        unsigned int switch_timer_interval,
 393                                        unsigned int read_timer_interval,
 394                                        int **shm_fd, int **wait_fd,
 395                                        uint64_t **memory_map_size,
 396                                        struct ltt_channel *chan_priv_init)
 397 {
 398         struct ltt_channel *chan = NULL;
 399         struct ltt_transport *transport;
 400
 401         if (session->been_active)
 402                 goto active;    /* Refuse to add channel to active session */
 403         transport = ltt_transport_find(transport_name);
 404         if (!transport) {
 405                 DBG("LTTng transport %s not found\n",
 406                        transport_name);
 407                 goto notransport;
 408         }
 409         chan_priv_init->id = session->free_chan_id++;
 410         chan_priv_init->session = session;
 411         /*
 412          * Note: the channel creation op already writes into the packet
 413          * headers. Therefore the "chan" information used as input
 414          * should be already accessible.
 415          */
 416         chan = transport->ops.channel_create("[lttng]", buf_addr,
 417                         subbuf_size, num_subbuf, switch_timer_interval,
 418                         read_timer_interval, shm_fd, wait_fd,
 419                         memory_map_size, chan_priv_init);
 420         if (!chan)
 421                 goto create_error;
 422         chan->enabled = 1;
 423         chan->ops = &transport->ops;
 424         cds_list_add(&chan->list, &session->chan);
 425         return chan;
 426
 427 create_error:
 428 notransport:
 429 active:
 430         return NULL;
 431 }
 432
 433 /*
 434  * Only used internally at session destruction.
 435  */
 436 static
 437 void _ltt_channel_destroy(struct ltt_channel *chan)
 438 {
 439         cds_list_del(&chan->list);
 440         lttng_destroy_context(chan->ctx);
 441         chan->ops->channel_destroy(chan);
 442 }
 443
 444 int ltt_loglevel_create(struct ltt_channel *chan,
 445         struct lttng_ust_event *event_param,
 446         struct session_loglevel **_sl)
 447 {
 448         struct session_loglevel *sl;
 449
 450         sl = add_loglevel(event_param->name, chan, event_param);
 451         if (!sl || IS_ERR(sl)) {
 452                 return PTR_ERR(sl);
 453         }
 454         *_sl = sl;
 455         return 0;
 456 }
 457
 458 static
 459 void _ltt_loglevel_destroy(struct session_loglevel *sl)
 460 {
 461         _remove_loglevel(sl);
 462 }
 463
 464 int ltt_wildcard_create(struct ltt_channel *chan,
 465         struct lttng_ust_event *event_param,
 466         struct session_wildcard **_sw)
 467 {
 468         struct session_wildcard *sw;
 469
 470         sw = add_wildcard(event_param->name, chan, event_param);
 471         if (!sw || IS_ERR(sw)) {
 472                 return PTR_ERR(sw);
 473         }
 474         *_sw = sw;
 475         return 0;
 476 }
 477
 478 static
 479 void _ltt_wildcard_destroy(struct session_wildcard *sw)
 480 {
 481         _remove_wildcard(sw);
 482 }
 483
 484 /*
 485  * Supports event creation while tracing session is active.
 486  */
 487 int ltt_event_create(struct ltt_channel *chan,
 488                 struct lttng_ust_event *event_param,
 489                 void *filter,
 490                 struct ltt_event **_event)
 491 {
 492         struct ltt_event *event;
 493         int ret = 0;
 494
 495         if (chan->used_event_id == -1UL) {
 496                 ret = -ENOMEM;
 497                 goto full;
 498         }
 499         /*
 500          * This is O(n^2) (for each event, the loop is called at event
 501          * creation). Might require a hash if we have lots of events.
 502          */
 503         cds_list_for_each_entry(event, &chan->session->events, list) {
 504                 if (event->desc && !strncmp(event->desc->name,
 505                                 event_param->name,
 506                                 LTTNG_UST_SYM_NAME_LEN - 1)) {
 507                         ret = -EEXIST;
 508                         goto exist;
 509                 }
 510         }
 511         event = zmalloc(sizeof(struct ltt_event));
 512         if (!event) {
 513                 ret = -ENOMEM;
 514                 goto cache_error;
 515         }
 516         event->chan = chan;
 517         event->filter = filter;
 518         /*
 519          * used_event_id counts the maximum number of event IDs that can
 520          * register if all probes register.
 521          */
 522         chan->used_event_id++;
 523         event->enabled = 1;
 524         event->instrumentation = event_param->instrumentation;
 525         /* Populate ltt_event structure before tracepoint registration. */
 526         cmm_smp_wmb();
 527         switch (event_param->instrumentation) {
 528         case LTTNG_UST_TRACEPOINT:
 529                 event->desc = ltt_event_get(event_param->name);
 530                 if (event->desc) {
 531                         ret = __tracepoint_probe_register(event_param->name,
 532                                         event->desc->probe_callback,
 533                                         event);
 534                         if (ret)
 535                                 goto register_error;
 536                         event->id = chan->free_event_id++;
 537                 } else {
 538                         /*
 539                          * If the probe is not present, event->desc stays NULL,
 540                          * waiting for the probe to register, and the event->id
 541                          * stays unallocated.
 542                          */
 543                         ret = add_pending_probe(event, event_param->name);
 544                         if (ret)
 545                                 goto add_pending_error;
 546                 }
 547                 break;
 548         case LTTNG_UST_TRACEPOINT_LOGLEVEL:
 549                 assert(0);
 550                 break;
 551         default:
 552                 WARN_ON_ONCE(1);
 553         }
 554         if (event->desc) {
 555                 ret = _ltt_event_metadata_statedump(chan->session, chan, event);
 556                 if (ret)
 557                         goto statedump_error;
 558         }
 559         cds_list_add(&event->list, &chan->session->events);
 560         *_event = event;
 561         return 0;
 562
 563 statedump_error:
 564         if (event->desc) {
 565                 WARN_ON_ONCE(__tracepoint_probe_unregister(event_param->name,
 566                                         event->desc->probe_callback,
 567                                         event));
 568                 ltt_event_put(event->desc);
 569         }
 570 add_pending_error:
 571 register_error:
 572         free(event);
 573 cache_error:
 574 exist:
 575 full:
 576         return ret;
 577 }
 578
 579 /*
 580  * Only used internally at session destruction.
 581  */
 582 int _ltt_event_unregister(struct ltt_event *event)
 583 {
 584         int ret = -EINVAL;
 585
 586         switch (event->instrumentation) {
 587         case LTTNG_UST_TRACEPOINT:
 588                 if (event->desc) {
 589                         ret = __tracepoint_probe_unregister(event->desc->name,
 590                                                           event->desc->probe_callback,
 591                                                           event);
 592                         if (ret)
 593                                 return ret;
 594                 } else {
 595                         remove_pending_probe(event->pending_probe);
 596                         ret = 0;
 597                 }
 598                 break;
 599         default:
 600                 WARN_ON_ONCE(1);
 601         }
 602         return ret;
 603 }
 604
 605 /*
 606  * Only used internally at session destruction.
 607  */
 608 static
 609 void _ltt_event_destroy(struct ltt_event *event)
 610 {
 611         switch (event->instrumentation) {
 612         case LTTNG_UST_TRACEPOINT:
 613                 if (event->desc) {
 614                         ltt_event_put(event->desc);
 615                 }
 616                 break;
 617         default:
 618                 WARN_ON_ONCE(1);
 619         }
 620         cds_list_del(&event->list);
 621         lttng_destroy_context(event->ctx);
 622         free(event);
 623 }
 624
 625 /*
 626  * We have exclusive access to our metadata buffer (protected by the
 627  * ust_lock), so we can do racy operations such as looking for
 628  * remaining space left in packet and write, since mutual exclusion
 629  * protects us from concurrent writes.
 630  */
 631 int lttng_metadata_printf(struct ltt_session *session,
 632                           const char *fmt, ...)
 633 {
 634         struct lttng_ust_lib_ring_buffer_ctx ctx;
 635         struct ltt_channel *chan = session->metadata;
 636         char *str = NULL;
 637         int ret = 0, waitret;
 638         size_t len, reserve_len, pos;
 639         va_list ap;
 640
 641         WARN_ON_ONCE(!CMM_ACCESS_ONCE(session->active));
 642
 643         va_start(ap, fmt);
 644         ret = vasprintf(&str, fmt, ap);
 645         va_end(ap);
 646         if (ret < 0)
 647                 return -ENOMEM;
 648
 649         len = strlen(str);
 650         pos = 0;
 651
 652         for (pos = 0; pos < len; pos += reserve_len) {
 653                 reserve_len = min_t(size_t,
 654                                 chan->ops->packet_avail_size(chan->chan, chan->handle),
 655                                 len - pos);
 656                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 657                                          sizeof(char), -1, chan->handle);
 658                 /*
 659                  * We don't care about metadata buffer's records lost
 660                  * count, because we always retry here. Report error if
 661                  * we need to bail out after timeout or being
 662                  * interrupted.
 663                  */
 664                 waitret = wait_cond_interruptible_timeout(
 665                         ({
 666                                 ret = chan->ops->event_reserve(&ctx, 0);
 667                                 ret != -ENOBUFS || !ret;
 668                         }),
 669                         LTTNG_METADATA_TIMEOUT_MSEC);
 670                 if (waitret == -ETIMEDOUT || waitret == -EINTR || ret) {
 671                         DBG("LTTng: Failure to write metadata to buffers (%s)\n",
 672                                 waitret == -EINTR ? "interrupted" :
 673                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 674                         if (waitret == -EINTR)
 675                                 ret = waitret;
 676                         goto end;
 677                 }
 678                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 679                 chan->ops->event_commit(&ctx);
 680         }
 681 end:
 682         free(str);
 683         return ret;
 684 }
 685
 686 static
 687 int _ltt_field_statedump(struct ltt_session *session,
 688                          const struct lttng_event_field *field)
 689 {
 690         int ret = 0;
 691
 692         switch (field->type.atype) {
 693         case atype_integer:
 694                 ret = lttng_metadata_printf(session,
 695                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 696                         field->type.u.basic.integer.size,
 697                         field->type.u.basic.integer.alignment,
 698                         field->type.u.basic.integer.signedness,
 699                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 700                                 ? "none"
 701                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 702                                         ? "UTF8"
 703                                         : "ASCII",
 704                         field->type.u.basic.integer.base,
 705 #if (BYTE_ORDER == BIG_ENDIAN)
 706                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 707 #else
 708                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 709 #endif
 710                         field->name);
 711                 break;
 712         case atype_float:
 713                 ret = lttng_metadata_printf(session,
 714                         "               floating_point { exp_dig = %u; mant_dig = %u; align = %u;%s } _%s;\n",
 715                         field->type.u.basic._float.exp_dig,
 716                         field->type.u.basic._float.mant_dig,
 717                         field->type.u.basic._float.alignment,
 718 #if (BYTE_ORDER == BIG_ENDIAN)
 719                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 720 #else
 721                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 722 #endif
 723                         field->name);
 724                 break;
 725         case atype_enum:
 726                 ret = lttng_metadata_printf(session,
 727                         "               %s %s;\n",
 728                         field->type.u.basic.enumeration.name,
 729                         field->name);
 730                 break;
 731         case atype_array:
 732         {
 733                 const struct lttng_basic_type *elem_type;
 734
 735                 elem_type = &field->type.u.array.elem_type;
 736                 ret = lttng_metadata_printf(session,
 737                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 738                         elem_type->u.basic.integer.size,
 739                         elem_type->u.basic.integer.alignment,
 740                         elem_type->u.basic.integer.signedness,
 741                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 742                                 ? "none"
 743                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 744                                         ? "UTF8"
 745                                         : "ASCII",
 746                         elem_type->u.basic.integer.base,
 747 #if (BYTE_ORDER == BIG_ENDIAN)
 748                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 749 #else
 750                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 751 #endif
 752                         field->name, field->type.u.array.length);
 753                 break;
 754         }
 755         case atype_sequence:
 756         {
 757                 const struct lttng_basic_type *elem_type;
 758                 const struct lttng_basic_type *length_type;
 759
 760                 elem_type = &field->type.u.sequence.elem_type;
 761                 length_type = &field->type.u.sequence.length_type;
 762                 ret = lttng_metadata_printf(session,
 763                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 764                         length_type->u.basic.integer.size,
 765                         (unsigned int) length_type->u.basic.integer.alignment,
 766                         length_type->u.basic.integer.signedness,
 767                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 768                                 ? "none"
 769                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 770                                         ? "UTF8"
 771                                         : "ASCII"),
 772                         length_type->u.basic.integer.base,
 773 #if (BYTE_ORDER == BIG_ENDIAN)
 774                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 775 #else
 776                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 777 #endif
 778                         field->name);
 779                 if (ret)
 780                         return ret;
 781
 782                 ret = lttng_metadata_printf(session,
 783                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 784                         elem_type->u.basic.integer.size,
 785                         (unsigned int) elem_type->u.basic.integer.alignment,
 786                         elem_type->u.basic.integer.signedness,
 787                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 788                                 ? "none"
 789                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 790                                         ? "UTF8"
 791                                         : "ASCII"),
 792                         elem_type->u.basic.integer.base,
 793 #if (BYTE_ORDER == BIG_ENDIAN)
 794                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 795 #else
 796                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 797 #endif
 798                         field->name,
 799                         field->name);
 800                 break;
 801         }
 802
 803         case atype_string:
 804                 /* Default encoding is UTF8 */
 805                 ret = lttng_metadata_printf(session,
 806                         "               string%s _%s;\n",
 807                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 808                                 " { encoding = ASCII; }" : "",
 809                         field->name);
 810                 break;
 811         default:
 812                 WARN_ON_ONCE(1);
 813                 return -EINVAL;
 814         }
 815         return ret;
 816 }
 817
 818 static
 819 int _ltt_context_metadata_statedump(struct ltt_session *session,
 820                                     struct lttng_ctx *ctx)
 821 {
 822         int ret = 0;
 823         int i;
 824
 825         if (!ctx)
 826                 return 0;
 827         for (i = 0; i < ctx->nr_fields; i++) {
 828                 const struct lttng_ctx_field *field = &ctx->fields[i];
 829
 830                 ret = _ltt_field_statedump(session, &field->event_field);
 831                 if (ret)
 832                         return ret;
 833         }
 834         return ret;
 835 }
 836
 837 static
 838 int _ltt_fields_metadata_statedump(struct ltt_session *session,
 839                                    struct ltt_event *event)
 840 {
 841         const struct lttng_event_desc *desc = event->desc;
 842         int ret = 0;
 843         int i;
 844
 845         for (i = 0; i < desc->nr_fields; i++) {
 846                 const struct lttng_event_field *field = &desc->fields[i];
 847
 848                 ret = _ltt_field_statedump(session, field);
 849                 if (ret)
 850                         return ret;
 851         }
 852         return ret;
 853 }
 854
 855 static
 856 int _ltt_event_metadata_statedump(struct ltt_session *session,
 857                                   struct ltt_channel *chan,
 858                                   struct ltt_event *event)
 859 {
 860         int ret = 0;
 861
 862         if (event->metadata_dumped || !CMM_ACCESS_ONCE(session->active))
 863                 return 0;
 864         if (chan == session->metadata)
 865                 return 0;
 866         /*
 867          * Don't print events for which probe load is pending.
 868          */
 869         if (!event->desc)
 870                 return 0;
 871
 872         ret = lttng_metadata_printf(session,
 873                 "event {\n"
 874                 "       name = \"%s\";\n"
 875                 "       id = %u;\n"
 876                 "       stream_id = %u;\n",
 877                 event->desc->name,
 878                 event->id,
 879                 event->chan->id);
 880         if (ret)
 881                 goto end;
 882
 883         if (event->desc->loglevel) {
 884                 const struct tracepoint_loglevel_entry *ll_entry;
 885
 886                 ll_entry = *event->desc->loglevel;
 887                 ret = lttng_metadata_printf(session,
 888                         "       loglevel.identifier = \"%s\";\n"
 889                         "       loglevel.value = %lld;\n",
 890                         ll_entry->identifier,
 891                         (long long) ll_entry->value);
 892                 if (ret)
 893                         goto end;
 894         }
 895
 896         if (event->ctx) {
 897                 ret = lttng_metadata_printf(session,
 898                         "       context := struct {\n");
 899                 if (ret)
 900                         goto end;
 901         }
 902         ret = _ltt_context_metadata_statedump(session, event->ctx);
 903         if (ret)
 904                 goto end;
 905         if (event->ctx) {
 906                 ret = lttng_metadata_printf(session,
 907                         "       };\n");
 908                 if (ret)
 909                         goto end;
 910         }
 911
 912         ret = lttng_metadata_printf(session,
 913                 "       fields := struct {\n"
 914                 );
 915         if (ret)
 916                 goto end;
 917
 918         ret = _ltt_fields_metadata_statedump(session, event);
 919         if (ret)
 920                 goto end;
 921
 922         /*
 923          * LTTng space reservation can only reserve multiples of the
 924          * byte size.
 925          */
 926         ret = lttng_metadata_printf(session,
 927                 "       };\n"
 928                 "};\n\n");
 929         if (ret)
 930                 goto end;
 931
 932         event->metadata_dumped = 1;
 933 end:
 934         return ret;
 935
 936 }
 937
 938 static
 939 int _ltt_channel_metadata_statedump(struct ltt_session *session,
 940                                     struct ltt_channel *chan)
 941 {
 942         int ret = 0;
 943
 944         if (chan->metadata_dumped || !CMM_ACCESS_ONCE(session->active))
 945                 return 0;
 946         if (chan == session->metadata)
 947                 return 0;
 948
 949         WARN_ON_ONCE(!chan->header_type);
 950         ret = lttng_metadata_printf(session,
 951                 "stream {\n"
 952                 "       id = %u;\n"
 953                 "       event.header := %s;\n"
 954                 "       packet.context := struct packet_context;\n",
 955                 chan->id,
 956                 chan->header_type == 1 ? "struct event_header_compact" :
 957                         "struct event_header_large");
 958         if (ret)
 959                 goto end;
 960
 961         if (chan->ctx) {
 962                 ret = lttng_metadata_printf(session,
 963                         "       event.context := struct {\n");
 964                 if (ret)
 965                         goto end;
 966         }
 967         ret = _ltt_context_metadata_statedump(session, chan->ctx);
 968         if (ret)
 969                 goto end;
 970         if (chan->ctx) {
 971                 ret = lttng_metadata_printf(session,
 972                         "       };\n");
 973                 if (ret)
 974                         goto end;
 975         }
 976
 977         ret = lttng_metadata_printf(session,
 978                 "};\n\n");
 979
 980         chan->metadata_dumped = 1;
 981 end:
 982         return ret;
 983 }
 984
 985 static
 986 int _ltt_stream_packet_context_declare(struct ltt_session *session)
 987 {
 988         return lttng_metadata_printf(session,
 989                 "struct packet_context {\n"
 990                 "       uint64_t timestamp_begin;\n"
 991                 "       uint64_t timestamp_end;\n"
 992                 "       uint32_t events_discarded;\n"
 993                 "       uint32_t content_size;\n"
 994                 "       uint32_t packet_size;\n"
 995                 "       uint32_t cpu_id;\n"
 996                 "};\n\n"
 997                 );
 998 }
 999
1000 /*
1001  * Compact header:
1002  * id: range: 0 - 30.
1003  * id 31 is reserved to indicate an extended header.
1004  *
1005  * Large header:
1006  * id: range: 0 - 65534.
1007  * id 65535 is reserved to indicate an extended header.
1008  */
1009 static
1010 int _ltt_event_header_declare(struct ltt_session *session)
1011 {
1012         return lttng_metadata_printf(session,
1013         "struct event_header_compact {\n"
1014         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
1015         "       variant <id> {\n"
1016         "               struct {\n"
1017         "                       uint27_t timestamp;\n"
1018         "               } compact;\n"
1019         "               struct {\n"
1020         "                       uint32_t id;\n"
1021         "                       uint64_t timestamp;\n"
1022         "               } extended;\n"
1023         "       } v;\n"
1024         "} align(%u);\n"
1025         "\n"
1026         "struct event_header_large {\n"
1027         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
1028         "       variant <id> {\n"
1029         "               struct {\n"
1030         "                       uint32_t timestamp;\n"
1031         "               } compact;\n"
1032         "               struct {\n"
1033         "                       uint32_t id;\n"
1034         "                       uint64_t timestamp;\n"
1035         "               } extended;\n"
1036         "       } v;\n"
1037         "} align(%u);\n\n",
1038         lttng_alignof(uint32_t) * CHAR_BIT,
1039         lttng_alignof(uint16_t) * CHAR_BIT
1040         );
1041 }
1042
1043 /*
1044  * Output metadata into this session's metadata buffers.
1045  */
1046 static
1047 int _ltt_session_metadata_statedump(struct ltt_session *session)
1048 {
1049         unsigned char *uuid_c = session->uuid;
1050         char uuid_s[37];
1051         struct ltt_channel *chan;
1052         struct ltt_event *event;
1053         int ret = 0;
1054
1055         if (!CMM_ACCESS_ONCE(session->active))
1056                 return 0;
1057         if (session->metadata_dumped)
1058                 goto skip_session;
1059         if (!session->metadata) {
1060                 DBG("LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
1061                 return -EPERM;
1062         }
1063
1064         snprintf(uuid_s, sizeof(uuid_s),
1065                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
1066                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
1067                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
1068                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
1069                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
1070
1071         ret = lttng_metadata_printf(session,
1072                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
1073                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
1074                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
1075                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
1076                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
1077                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
1078                 "\n"
1079                 "trace {\n"
1080                 "       major = %u;\n"
1081                 "       minor = %u;\n"
1082                 "       uuid = \"%s\";\n"
1083                 "       byte_order = %s;\n"
1084                 "       packet.header := struct {\n"
1085                 "               uint32_t magic;\n"
1086                 "               uint8_t  uuid[16];\n"
1087                 "               uint32_t stream_id;\n"
1088                 "       };\n"
1089                 "};\n\n",
1090                 lttng_alignof(uint8_t) * CHAR_BIT,
1091                 lttng_alignof(uint16_t) * CHAR_BIT,
1092                 lttng_alignof(uint32_t) * CHAR_BIT,
1093                 lttng_alignof(uint64_t) * CHAR_BIT,
1094                 CTF_VERSION_MAJOR,
1095                 CTF_VERSION_MINOR,
1096                 uuid_s,
1097 #if (BYTE_ORDER == BIG_ENDIAN)
1098                 "be"
1099 #else
1100                 "le"
1101 #endif
1102                 );
1103         if (ret)
1104                 goto end;
1105
1106         ret = _ltt_stream_packet_context_declare(session);
1107         if (ret)
1108                 goto end;
1109
1110         ret = _ltt_event_header_declare(session);
1111         if (ret)
1112                 goto end;
1113
1114 skip_session:
1115         cds_list_for_each_entry(chan, &session->chan, list) {
1116                 ret = _ltt_channel_metadata_statedump(session, chan);
1117                 if (ret)
1118                         goto end;
1119         }
1120
1121         cds_list_for_each_entry(event, &session->events, list) {
1122                 ret = _ltt_event_metadata_statedump(session, event->chan, event);
1123                 if (ret)
1124                         goto end;
1125         }
1126         session->metadata_dumped = 1;
1127 end:
1128         return ret;
1129 }
1130
1131 void lttng_ust_events_exit(void)
1132 {
1133         struct ltt_session *session, *tmpsession;
1134
1135         cds_list_for_each_entry_safe(session, tmpsession, &sessions, list)
1136                 ltt_session_destroy(session);
1137 }