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