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
   9 #include <linux/module.h>
  10 #include <linux/list.h>
  11 #include <linux/mutex.h>
  12 #include <linux/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/jiffies.h>
  15 #include <linux/uuid.h>
  16 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  17 #include "ltt-events.h"
  18 #include "ltt-tracer.h"
  19
  20 static LIST_HEAD(sessions);
  21 static LIST_HEAD(ltt_transport_list);
  22 static DEFINE_MUTEX(sessions_mutex);
  23 static struct kmem_cache *event_cache;
  24
  25 static void _ltt_event_destroy(struct ltt_event *event);
  26 static void _ltt_channel_destroy(struct ltt_channel *chan);
  27 static int _ltt_event_unregister(struct ltt_event *event);
  28 static
  29 int _ltt_event_metadata_statedump(struct ltt_session *session,
  30                                   struct ltt_channel *chan,
  31                                   struct ltt_event *event);
  32 static
  33 int _ltt_session_metadata_statedump(struct ltt_session *session);
  34
  35
  36 static
  37 void synchronize_trace(void)
  38 {
  39         synchronize_sched();
  40 #ifdef CONFIG_PREEMPT_RT
  41         synchronize_rcu();
  42 #endif
  43 }
  44
  45 struct ltt_session *ltt_session_create(void)
  46 {
  47         struct ltt_session *session;
  48
  49         mutex_lock(&sessions_mutex);
  50         session = kzalloc(sizeof(struct ltt_session), GFP_KERNEL);
  51         if (!session)
  52                 return NULL;
  53         INIT_LIST_HEAD(&session->chan);
  54         INIT_LIST_HEAD(&session->events);
  55         uuid_le_gen(&session->uuid);
  56         list_add(&session->list, &sessions);
  57         mutex_unlock(&sessions_mutex);
  58         return session;
  59 }
  60
  61 void ltt_session_destroy(struct ltt_session *session)
  62 {
  63         struct ltt_channel *chan, *tmpchan;
  64         struct ltt_event *event, *tmpevent;
  65         int ret;
  66
  67         mutex_lock(&sessions_mutex);
  68         ACCESS_ONCE(session->active) = 0;
  69         list_for_each_entry(event, &session->events, list) {
  70                 ret = _ltt_event_unregister(event);
  71                 WARN_ON(ret);
  72         }
  73         synchronize_trace();    /* Wait for in-flight events to complete */
  74         list_for_each_entry_safe(event, tmpevent, &session->events, list)
  75                 _ltt_event_destroy(event);
  76         list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
  77                 _ltt_channel_destroy(chan);
  78         list_del(&session->list);
  79         mutex_unlock(&sessions_mutex);
  80         kfree(session);
  81 }
  82
  83 int ltt_session_start(struct ltt_session *session)
  84 {
  85         int ret = 0;
  86         struct ltt_channel *chan;
  87
  88         mutex_lock(&sessions_mutex);
  89         if (session->active) {
  90                 ret = -EBUSY;
  91                 goto end;
  92         }
  93
  94         /*
  95          * Snapshot the number of events per channel to know the type of header
  96          * we need to use.
  97          */
  98         list_for_each_entry(chan, &session->chan, list) {
  99                 if (chan->header_type)
 100                         continue;               /* don't change it if session stop/restart */
 101                 if (chan->free_event_id < 31)
 102                         chan->header_type = 1;  /* compact */
 103                 else
 104                         chan->header_type = 2;  /* large */
 105         }
 106
 107         ACCESS_ONCE(session->active) = 1;
 108         ACCESS_ONCE(session->been_active) = 1;
 109         synchronize_trace();    /* Wait for in-flight events to complete */
 110         ret = _ltt_session_metadata_statedump(session);
 111         if (ret) {
 112                 ACCESS_ONCE(session->active) = 0;
 113                 synchronize_trace();    /* Wait for in-flight events to complete */
 114         }
 115 end:
 116         mutex_unlock(&sessions_mutex);
 117         return ret;
 118 }
 119
 120 int ltt_session_stop(struct ltt_session *session)
 121 {
 122         int ret = 0;
 123
 124         mutex_lock(&sessions_mutex);
 125         if (!session->active) {
 126                 ret = -EBUSY;
 127                 goto end;
 128         }
 129         ACCESS_ONCE(session->active) = 0;
 130         synchronize_trace();    /* Wait for in-flight events to complete */
 131 end:
 132         mutex_unlock(&sessions_mutex);
 133         return ret;
 134 }
 135
 136 static struct ltt_transport *ltt_transport_find(const char *name)
 137 {
 138         struct ltt_transport *transport;
 139
 140         list_for_each_entry(transport, &ltt_transport_list, node) {
 141                 if (!strcmp(transport->name, name))
 142                         return transport;
 143         }
 144         return NULL;
 145 }
 146
 147 struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 148                                        const char *transport_name,
 149                                        void *buf_addr,
 150                                        size_t subbuf_size, size_t num_subbuf,
 151                                        unsigned int switch_timer_interval,
 152                                        unsigned int read_timer_interval)
 153 {
 154         struct ltt_channel *chan;
 155         struct ltt_transport *transport;
 156
 157         mutex_lock(&sessions_mutex);
 158         if (session->been_active)
 159                 goto active;    /* Refuse to add channel to active session */
 160         transport = ltt_transport_find(transport_name);
 161         if (!transport) {
 162                 printk(KERN_WARNING "LTTng transport %s not found\n",
 163                        transport_name);
 164                 goto notransport;
 165         }
 166         chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL);
 167         if (!chan)
 168                 goto nomem;
 169         chan->session = session;
 170         init_waitqueue_head(&chan->notify_wait);
 171         chan->id = session->free_chan_id++;
 172         /*
 173          * Note: the channel creation op already writes into the packet
 174          * headers. Therefore the "chan" information used as input
 175          * should be already accessible.
 176          */
 177         chan->chan = transport->ops.channel_create("[lttng]", chan, buf_addr,
 178                         subbuf_size, num_subbuf, switch_timer_interval,
 179                         read_timer_interval);
 180         if (!chan->chan)
 181                 goto create_error;
 182         chan->ops = &transport->ops;
 183         list_add(&chan->list, &session->chan);
 184         mutex_unlock(&sessions_mutex);
 185         return chan;
 186
 187 create_error:
 188         kfree(chan);
 189 nomem:
 190 notransport:
 191 active:
 192         mutex_unlock(&sessions_mutex);
 193         return NULL;
 194 }
 195
 196 /*
 197  * Only used internally at session destruction.
 198  */
 199 static
 200 void _ltt_channel_destroy(struct ltt_channel *chan)
 201 {
 202         chan->ops->channel_destroy(chan->chan);
 203         list_del(&chan->list);
 204         lttng_destroy_context(chan->ctx);
 205         kfree(chan);
 206 }
 207
 208 /*
 209  * Supports event creation while tracing session is active.
 210  */
 211 struct ltt_event *ltt_event_create(struct ltt_channel *chan,
 212                                    struct lttng_kernel_event *event_param,
 213                                    void *filter)
 214 {
 215         struct ltt_event *event;
 216         int ret;
 217
 218         mutex_lock(&sessions_mutex);
 219         if (chan->free_event_id == -1UL)
 220                 goto full;
 221         /*
 222          * This is O(n^2) (for each event, the loop is called at event
 223          * creation). Might require a hash if we have lots of events.
 224          */
 225         list_for_each_entry(event, &chan->session->events, list)
 226                 if (!strcmp(event->desc->name, event_param->name))
 227                         goto exist;
 228         event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
 229         if (!event)
 230                 goto cache_error;
 231         event->chan = chan;
 232         event->filter = filter;
 233         event->id = chan->free_event_id++;
 234         event->instrumentation = event_param->instrumentation;
 235         /* Populate ltt_event structure before tracepoint registration. */
 236         smp_wmb();
 237         switch (event_param->instrumentation) {
 238         case LTTNG_KERNEL_TRACEPOINT:
 239                 event->desc = ltt_event_get(event_param->name);
 240                 if (!event->desc)
 241                         goto register_error;
 242                 ret = tracepoint_probe_register(event_param->name,
 243                                 event->desc->probe_callback,
 244                                 event);
 245                 if (ret)
 246                         goto register_error;
 247                 break;
 248         case LTTNG_KERNEL_KPROBE:
 249                 ret = lttng_kprobes_register(event_param->name,
 250                                 event_param->u.kprobe.symbol_name,
 251                                 event_param->u.kprobe.offset,
 252                                 event_param->u.kprobe.addr,
 253                                 event);
 254                 if (ret)
 255                         goto register_error;
 256                 ret = try_module_get(event->desc->owner);
 257                 WARN_ON_ONCE(!ret);
 258                 break;
 259         case LTTNG_KERNEL_FUNCTION:
 260                 ret = lttng_ftrace_register(event_param->name,
 261                                 event_param->u.ftrace.symbol_name,
 262                                 event);
 263                 if (ret)
 264                         goto register_error;
 265                 ret = try_module_get(event->desc->owner);
 266                 WARN_ON_ONCE(!ret);
 267                 break;
 268         default:
 269                 WARN_ON_ONCE(1);
 270         }
 271         ret = _ltt_event_metadata_statedump(chan->session, chan, event);
 272         if (ret)
 273                 goto statedump_error;
 274         list_add(&event->list, &chan->session->events);
 275         mutex_unlock(&sessions_mutex);
 276         return event;
 277
 278 statedump_error:
 279         WARN_ON_ONCE(tracepoint_probe_unregister(event_param->name,
 280                                 event->desc->probe_callback,
 281                                 event));
 282         ltt_event_put(event->desc);
 283 register_error:
 284         kmem_cache_free(event_cache, event);
 285 cache_error:
 286 exist:
 287 full:
 288         mutex_unlock(&sessions_mutex);
 289         return NULL;
 290 }
 291
 292 /*
 293  * Only used internally at session destruction.
 294  */
 295 int _ltt_event_unregister(struct ltt_event *event)
 296 {
 297         int ret = -EINVAL;
 298
 299         switch (event->instrumentation) {
 300         case LTTNG_KERNEL_TRACEPOINT:
 301                 ret = tracepoint_probe_unregister(event->desc->name,
 302                                                   event->desc->probe_callback,
 303                                                   event);
 304                 if (ret)
 305                         return ret;
 306                 break;
 307         case LTTNG_KERNEL_KPROBE:
 308                 lttng_kprobes_unregister(event);
 309                 ret = 0;
 310                 break;
 311         case LTTNG_KERNEL_FUNCTION:
 312                 lttng_ftrace_unregister(event);
 313                 ret = 0;
 314                 break;
 315         default:
 316                 WARN_ON_ONCE(1);
 317         }
 318         return ret;
 319 }
 320
 321 /*
 322  * Only used internally at session destruction.
 323  */
 324 static
 325 void _ltt_event_destroy(struct ltt_event *event)
 326 {
 327         switch (event->instrumentation) {
 328         case LTTNG_KERNEL_TRACEPOINT:
 329                 ltt_event_put(event->desc);
 330                 break;
 331         case LTTNG_KERNEL_KPROBE:
 332                 module_put(event->desc->owner);
 333                 lttng_kprobes_destroy_private(event);
 334                 break;
 335         case LTTNG_KERNEL_FUNCTION:
 336                 module_put(event->desc->owner);
 337                 lttng_ftrace_destroy_private(event);
 338                 break;
 339         default:
 340                 WARN_ON_ONCE(1);
 341         }
 342         list_del(&event->list);
 343         lttng_destroy_context(event->ctx);
 344         kmem_cache_free(event_cache, event);
 345 }
 346
 347 /*
 348  * We have exclusive access to our metadata buffer (protected by the
 349  * sessions_mutex), so we can do racy operations such as looking for
 350  * remaining space left in packet and write, since mutual exclusion
 351  * protects us from concurrent writes.
 352  */
 353 int lttng_metadata_printf(struct ltt_session *session,
 354                           const char *fmt, ...)
 355 {
 356         struct lib_ring_buffer_ctx ctx;
 357         struct ltt_channel *chan = session->metadata;
 358         char *str;
 359         int ret = 0, waitret;
 360         size_t len, reserve_len, pos;
 361         va_list ap;
 362
 363         WARN_ON_ONCE(!ACCESS_ONCE(session->active));
 364
 365         va_start(ap, fmt);
 366         str = kvasprintf(GFP_KERNEL, fmt, ap);
 367         va_end(ap);
 368         if (!str)
 369                 return -ENOMEM;
 370
 371         len = strlen(str);
 372         pos = 0;
 373
 374         for (pos = 0; pos < len; pos += reserve_len) {
 375                 reserve_len = min_t(size_t,
 376                                 chan->ops->packet_avail_size(chan->chan),
 377                                 len - pos);
 378                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 379                                          sizeof(char), -1);
 380                 /*
 381                  * We don't care about metadata buffer's records lost
 382                  * count, because we always retry here. Report error if
 383                  * we need to bail out after timeout or being
 384                  * interrupted.
 385                  */
 386                 waitret = wait_event_interruptible_timeout(*chan->ops->get_reader_wait_queue(chan),
 387                         ({
 388                                 ret = chan->ops->event_reserve(&ctx, 0);
 389                                 ret != -ENOBUFS || !ret;
 390                         }),
 391                         msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC));
 392                 if (!waitret || waitret == -ERESTARTSYS || ret) {
 393                         printk(KERN_WARNING "LTTng: Failure to write metadata to buffers (%s)\n",
 394                                 waitret == -ERESTARTSYS ? "interrupted" :
 395                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 396                         if (waitret == -ERESTARTSYS)
 397                                 ret = waitret;
 398                         goto end;
 399                 }
 400                 chan->ops->event_write(&ctx, &str[pos], len);
 401                 chan->ops->event_commit(&ctx);
 402         }
 403 end:
 404         kfree(str);
 405         return ret;
 406 }
 407
 408 static
 409 int _ltt_field_statedump(struct ltt_session *session,
 410                          const struct lttng_event_field *field)
 411 {
 412         int ret = 0;
 413
 414         switch (field->type.atype) {
 415         case atype_integer:
 416                 ret = lttng_metadata_printf(session,
 417                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s;\n",
 418                         field->type.u.basic.integer.size,
 419                         field->type.u.basic.integer.alignment,
 420                         field->type.u.basic.integer.signedness,
 421                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 422                                 ? "none"
 423                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 424                                         ? "UTF8"
 425                                         : "ASCII",
 426                         field->type.u.basic.integer.base,
 427 #ifdef __BIG_ENDIAN
 428                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 429 #else
 430                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 431 #endif
 432                         field->name);
 433                 break;
 434         case atype_enum:
 435                 ret = lttng_metadata_printf(session,
 436                         "               %s %s;\n",
 437                         field->type.u.basic.enumeration.name,
 438                         field->name);
 439                 break;
 440         case atype_array:
 441         {
 442                 const struct lttng_basic_type *elem_type;
 443
 444                 elem_type = &field->type.u.array.elem_type;
 445                 ret = lttng_metadata_printf(session,
 446                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[%u];\n",
 447                         elem_type->u.basic.integer.size,
 448                         elem_type->u.basic.integer.alignment,
 449                         elem_type->u.basic.integer.signedness,
 450                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 451                                 ? "none"
 452                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 453                                         ? "UTF8"
 454                                         : "ASCII",
 455                         elem_type->u.basic.integer.base,
 456 #ifdef __BIG_ENDIAN
 457                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 458 #else
 459                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 460 #endif
 461                         field->name, field->type.u.array.length);
 462                 break;
 463         }
 464         case atype_sequence:
 465         {
 466                 const struct lttng_basic_type *elem_type;
 467                 const struct lttng_basic_type *length_type;
 468
 469                 elem_type = &field->type.u.sequence.elem_type;
 470                 length_type = &field->type.u.sequence.length_type;
 471                 ret = lttng_metadata_printf(session,
 472                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 473                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[ __%s_length ];\n",
 474                         length_type->u.basic.integer.size,
 475                         length_type->u.basic.integer.alignment,
 476                         length_type->u.basic.integer.signedness,
 477                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 478                                 ? "none"
 479                                 : (length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 480                                         ? "UTF8"
 481                                         : "ASCII",
 482                         length_type->u.basic.integer.base,
 483 #ifdef __BIG_ENDIAN
 484                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 485 #else
 486                         length_type->u.basic.integer.reverse_byte_order
 487 ? " byte_order = be;" : "",
 488 #endif
 489                         field->name,
 490                         elem_type->u.basic.integer.size,
 491                         elem_type->u.basic.integer.alignment,
 492                         elem_type->u.basic.integer.signedness,
 493                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 494                                 ? "none"
 495                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 496                                         ? "UTF8"
 497                                         : "ASCII",
 498                         elem_type->u.basic.integer.base,
 499 #ifdef __BIG_ENDIAN
 500                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 501 #else
 502                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 503 #endif
 504                         field->name,
 505                         field->name
 506                         );
 507                 break;
 508         }
 509
 510         case atype_string:
 511                 /* Default encoding is UTF8 */
 512                 ret = lttng_metadata_printf(session,
 513                         "               string%s %s;\n",
 514                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 515                                 " { encoding = ASCII; }" : "",
 516                         field->name);
 517                 break;
 518         default:
 519                 WARN_ON_ONCE(1);
 520                 return -EINVAL;
 521         }
 522         return ret;
 523 }
 524
 525 static
 526 int _ltt_context_metadata_statedump(struct ltt_session *session,
 527                                     struct lttng_ctx *ctx)
 528 {
 529         int ret = 0;
 530         int i;
 531
 532         if (!ctx)
 533                 return 0;
 534         for (i = 0; i < ctx->nr_fields; i++) {
 535                 const struct lttng_ctx_field *field = &ctx->fields[i];
 536
 537                 ret = _ltt_field_statedump(session, &field->event_field);
 538                 if (ret)
 539                         return ret;
 540         }
 541         return ret;
 542 }
 543
 544 static
 545 int _ltt_fields_metadata_statedump(struct ltt_session *session,
 546                                    struct ltt_event *event)
 547 {
 548         const struct lttng_event_desc *desc = event->desc;
 549         int ret = 0;
 550         int i;
 551
 552         for (i = 0; i < desc->nr_fields; i++) {
 553                 const struct lttng_event_field *field = &desc->fields[i];
 554
 555                 ret = _ltt_field_statedump(session, field);
 556                 if (ret)
 557                         return ret;
 558         }
 559         return ret;
 560 }
 561
 562 static
 563 int _ltt_event_metadata_statedump(struct ltt_session *session,
 564                                   struct ltt_channel *chan,
 565                                   struct ltt_event *event)
 566 {
 567         int ret = 0;
 568
 569         if (event->metadata_dumped || !ACCESS_ONCE(session->active))
 570                 return 0;
 571         if (chan == session->metadata)
 572                 return 0;
 573
 574         ret = lttng_metadata_printf(session,
 575                 "event {\n"
 576                 "       name = %s;\n"
 577                 "       id = %u;\n"
 578                 "       stream_id = %u;\n"
 579                 "       context := struct {\n",
 580                 event->desc->name,
 581                 event->id,
 582                 event->chan->id);
 583         if (ret)
 584                 goto end;
 585
 586         ret = _ltt_context_metadata_statedump(session, event->ctx);
 587         if (ret)
 588                 goto end;
 589
 590         ret = lttng_metadata_printf(session,
 591                 "       };\n"
 592                 "       fields := struct {\n"
 593                 );
 594         if (ret)
 595                 goto end;
 596
 597         ret = _ltt_fields_metadata_statedump(session, event);
 598         if (ret)
 599                 goto end;
 600
 601         /*
 602          * LTTng space reservation can only reserve multiples of the
 603          * byte size.
 604          */
 605         ret = lttng_metadata_printf(session,
 606                 "       };\n"
 607                 "};\n\n");
 608         if (ret)
 609                 goto end;
 610
 611         event->metadata_dumped = 1;
 612 end:
 613         return ret;
 614
 615 }
 616
 617 static
 618 int _ltt_channel_metadata_statedump(struct ltt_session *session,
 619                                     struct ltt_channel *chan)
 620 {
 621         int ret = 0;
 622
 623         if (chan->metadata_dumped || !ACCESS_ONCE(session->active))
 624                 return 0;
 625         if (chan == session->metadata)
 626                 return 0;
 627
 628         WARN_ON_ONCE(!chan->header_type);
 629         ret = lttng_metadata_printf(session,
 630                 "stream {\n"
 631                 "       id = %u;\n"
 632                 "       event.header := %s;\n"
 633                 "       packet.context := struct packet_context;\n"
 634                 "       event.context := {\n",
 635                 chan->id,
 636                 chan->header_type == 1 ? "struct event_header_compact" :
 637                         "struct event_header_large");
 638         if (ret)
 639                 goto end;
 640
 641         ret = _ltt_context_metadata_statedump(session, chan->ctx);
 642         if (ret)
 643                 goto end;
 644
 645         ret = lttng_metadata_printf(session,
 646                 "       };\n"
 647                 "};\n\n"
 648                 );
 649
 650         chan->metadata_dumped = 1;
 651 end:
 652         return ret;
 653 }
 654
 655 static
 656 int _ltt_stream_packet_context_declare(struct ltt_session *session)
 657 {
 658         return lttng_metadata_printf(session,
 659                 "struct packet_context {\n"
 660                 "       uint64_t timestamp_begin;\n"
 661                 "       uint64_t timestamp_end;\n"
 662                 "       uint32_t events_discarded;\n"
 663                 "       uint32_t content_size;\n"
 664                 "       uint32_t packet_size;\n"
 665                 "       uint32_t cpu_id;\n"
 666                 "};\n\n"
 667                 );
 668 }
 669
 670 /*
 671  * Compact header:
 672  * id: range: 0 - 30.
 673  * id 31 is reserved to indicate an extended header.
 674  *
 675  * Large header:
 676  * id: range: 0 - 65534.
 677  * id 65535 is reserved to indicate an extended header.
 678  */
 679 static
 680 int _ltt_event_header_declare(struct ltt_session *session)
 681 {
 682         return lttng_metadata_printf(session,
 683         "struct event_header_compact {\n"
 684         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
 685         "       variant <id> {\n"
 686         "               struct {\n"
 687         "                       uint27_t timestamp;\n"
 688         "               } compact;\n"
 689         "               struct {\n"
 690         "                       uint32_t id;\n"
 691         "                       uint64_t timestamp;\n"
 692         "               } extended;\n"
 693         "       } v;\n"
 694         "} align(%u);\n"
 695         "\n"
 696         "struct event_header_large {\n"
 697         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
 698         "       variant <id> {\n"
 699         "               struct {\n"
 700         "                       uint32_t timestamp;\n"
 701         "               } compact;\n"
 702         "               struct {\n"
 703         "                       uint32_t id;\n"
 704         "                       uint64_t timestamp;\n"
 705         "               } extended;\n"
 706         "       } v;\n"
 707         "} align(%u);\n\n",
 708         ltt_alignof(uint32_t) * CHAR_BIT,
 709         ltt_alignof(uint16_t) * CHAR_BIT
 710         );
 711 }
 712
 713 /*
 714  * Output metadata into this session's metadata buffers.
 715  */
 716 static
 717 int _ltt_session_metadata_statedump(struct ltt_session *session)
 718 {
 719         unsigned char *uuid_c = session->uuid.b;
 720         unsigned char uuid_s[37];
 721         struct ltt_channel *chan;
 722         struct ltt_event *event;
 723         int ret = 0;
 724
 725         if (!ACCESS_ONCE(session->active))
 726                 return 0;
 727         if (session->metadata_dumped)
 728                 goto skip_session;
 729         if (!session->metadata) {
 730                 printk(KERN_WARNING "LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
 731                 return -EPERM;
 732         }
 733
 734         snprintf(uuid_s, sizeof(uuid_s),
 735                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 736                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
 737                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
 738                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
 739                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
 740
 741         ret = lttng_metadata_printf(session,
 742                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
 743                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
 744                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
 745                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
 746                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
 747                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
 748                 "\n"
 749                 "trace {\n"
 750                 "       major = %u;\n"
 751                 "       minor = %u;\n"
 752                 "       uuid = \"%s\";\n"
 753                 "       byte_order = %s;\n"
 754                 "       packet.header := struct {\n"
 755                 "               uint32_t magic;\n"
 756                 "               uint8_t  uuid[16];\n"
 757                 "               uint32_t stream_id;\n"
 758                 "       };\n"
 759                 "};\n\n",
 760                 ltt_alignof(uint8_t) * CHAR_BIT,
 761                 ltt_alignof(uint16_t) * CHAR_BIT,
 762                 ltt_alignof(uint32_t) * CHAR_BIT,
 763                 ltt_alignof(uint64_t) * CHAR_BIT,
 764                 CTF_VERSION_MAJOR,
 765                 CTF_VERSION_MINOR,
 766                 uuid_s,
 767 #ifdef __BIG_ENDIAN
 768                 "be"
 769 #else
 770                 "le"
 771 #endif
 772                 );
 773         if (ret)
 774                 goto end;
 775
 776         ret = _ltt_stream_packet_context_declare(session);
 777         if (ret)
 778                 goto end;
 779
 780         ret = _ltt_event_header_declare(session);
 781         if (ret)
 782                 goto end;
 783
 784 skip_session:
 785         list_for_each_entry(chan, &session->chan, list) {
 786                 ret = _ltt_channel_metadata_statedump(session, chan);
 787                 if (ret)
 788                         goto end;
 789         }
 790
 791         list_for_each_entry(event, &session->events, list) {
 792                 ret = _ltt_event_metadata_statedump(session, event->chan, event);
 793                 if (ret)
 794                         goto end;
 795         }
 796         session->metadata_dumped = 1;
 797 end:
 798         return ret;
 799 }
 800
 801 /**
 802  * ltt_transport_register - LTT transport registration
 803  * @transport: transport structure
 804  *
 805  * Registers a transport which can be used as output to extract the data out of
 806  * LTTng. The module calling this registration function must ensure that no
 807  * trap-inducing code will be executed by the transport functions. E.g.
 808  * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
 809  * is made visible to the transport function. This registration acts as a
 810  * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
 811  * after its registration must it synchronize the TLBs.
 812  */
 813 void ltt_transport_register(struct ltt_transport *transport)
 814 {
 815         /*
 816          * Make sure no page fault can be triggered by the module about to be
 817          * registered. We deal with this here so we don't have to call
 818          * vmalloc_sync_all() in each module's init.
 819          */
 820         wrapper_vmalloc_sync_all();
 821
 822         mutex_lock(&sessions_mutex);
 823         list_add_tail(&transport->node, &ltt_transport_list);
 824         mutex_unlock(&sessions_mutex);
 825 }
 826 EXPORT_SYMBOL_GPL(ltt_transport_register);
 827
 828 /**
 829  * ltt_transport_unregister - LTT transport unregistration
 830  * @transport: transport structure
 831  */
 832 void ltt_transport_unregister(struct ltt_transport *transport)
 833 {
 834         mutex_lock(&sessions_mutex);
 835         list_del(&transport->node);
 836         mutex_unlock(&sessions_mutex);
 837 }
 838 EXPORT_SYMBOL_GPL(ltt_transport_unregister);
 839
 840 static int __init ltt_events_init(void)
 841 {
 842         int ret;
 843
 844         event_cache = KMEM_CACHE(ltt_event, 0);
 845         if (!event_cache)
 846                 return -ENOMEM;
 847         ret = ltt_debugfs_abi_init();
 848         if (ret)
 849                 goto error_abi;
 850         return 0;
 851 error_abi:
 852         kmem_cache_destroy(event_cache);
 853         return ret;
 854 }
 855
 856 module_init(ltt_events_init);
 857
 858 static void __exit ltt_events_exit(void)
 859 {
 860         struct ltt_session *session, *tmpsession;
 861
 862         ltt_debugfs_abi_exit();
 863         list_for_each_entry_safe(session, tmpsession, &sessions, list)
 864                 ltt_session_destroy(session);
 865         kmem_cache_destroy(event_cache);
 866 }
 867
 868 module_exit(ltt_events_exit);
 869
 870 MODULE_LICENSE("GPL and additional rights");
 871 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 872 MODULE_DESCRIPTION("LTTng Events");