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 #include <linux/module.h>
  12 #include <linux/list.h>
  13 #include <linux/mutex.h>
  14 #include <linux/sched.h>
  15 #include <linux/slab.h>
  16 #include <linux/jiffies.h>
  17 #include "wrapper/uuid.h"
  18 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  19 #include "ltt-events.h"
  20 #include "ltt-tracer.h"
  21
  22 static LIST_HEAD(sessions);
  23 static LIST_HEAD(ltt_transport_list);
  24 static DEFINE_MUTEX(sessions_mutex);
  25 static struct kmem_cache *event_cache;
  26
  27 static void _ltt_event_destroy(struct ltt_event *event);
  28 static void _ltt_channel_destroy(struct ltt_channel *chan);
  29 static int _ltt_event_unregister(struct ltt_event *event);
  30 static
  31 int _ltt_event_metadata_statedump(struct ltt_session *session,
  32                                   struct ltt_channel *chan,
  33                                   struct ltt_event *event);
  34 static
  35 int _ltt_session_metadata_statedump(struct ltt_session *session);
  36
  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_enable(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         ret = _ltt_session_metadata_statedump(session);
 110         if (ret)
 111                 ACCESS_ONCE(session->active) = 0;
 112 end:
 113         mutex_unlock(&sessions_mutex);
 114         return ret;
 115 }
 116
 117 int ltt_session_disable(struct ltt_session *session)
 118 {
 119         int ret = 0;
 120
 121         mutex_lock(&sessions_mutex);
 122         if (!session->active) {
 123                 ret = -EBUSY;
 124                 goto end;
 125         }
 126         ACCESS_ONCE(session->active) = 0;
 127 end:
 128         mutex_unlock(&sessions_mutex);
 129         return ret;
 130 }
 131
 132 int ltt_channel_enable(struct ltt_channel *channel)
 133 {
 134         int old;
 135
 136         if (channel == channel->session->metadata)
 137                 return -EPERM;
 138         old = xchg(&channel->enabled, 1);
 139         if (old)
 140                 return -EEXIST;
 141         return 0;
 142 }
 143
 144 int ltt_channel_disable(struct ltt_channel *channel)
 145 {
 146         int old;
 147
 148         if (channel == channel->session->metadata)
 149                 return -EPERM;
 150         old = xchg(&channel->enabled, 0);
 151         if (!old)
 152                 return -EEXIST;
 153         return 0;
 154 }
 155
 156 int ltt_event_enable(struct ltt_event *event)
 157 {
 158         int old;
 159
 160         if (event->chan == event->chan->session->metadata)
 161                 return -EPERM;
 162         old = xchg(&event->enabled, 1);
 163         if (old)
 164                 return -EEXIST;
 165         return 0;
 166 }
 167
 168 int ltt_event_disable(struct ltt_event *event)
 169 {
 170         int old;
 171
 172         if (event->chan == event->chan->session->metadata)
 173                 return -EPERM;
 174         old = xchg(&event->enabled, 0);
 175         if (!old)
 176                 return -EEXIST;
 177         return 0;
 178 }
 179
 180 static struct ltt_transport *ltt_transport_find(const char *name)
 181 {
 182         struct ltt_transport *transport;
 183
 184         list_for_each_entry(transport, &ltt_transport_list, node) {
 185                 if (!strcmp(transport->name, name))
 186                         return transport;
 187         }
 188         return NULL;
 189 }
 190
 191 struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 192                                        const char *transport_name,
 193                                        void *buf_addr,
 194                                        size_t subbuf_size, size_t num_subbuf,
 195                                        unsigned int switch_timer_interval,
 196                                        unsigned int read_timer_interval)
 197 {
 198         struct ltt_channel *chan;
 199         struct ltt_transport *transport = NULL;
 200
 201         mutex_lock(&sessions_mutex);
 202         if (session->been_active)
 203                 goto active;    /* Refuse to add channel to active session */
 204         transport = ltt_transport_find(transport_name);
 205         if (!transport) {
 206                 printk(KERN_WARNING "LTTng transport %s not found\n",
 207                        transport_name);
 208                 goto notransport;
 209         }
 210         if (!try_module_get(transport->owner)) {
 211                 printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 212                 goto notransport;
 213         }
 214         chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL);
 215         if (!chan)
 216                 goto nomem;
 217         chan->session = session;
 218         chan->id = session->free_chan_id++;
 219         /*
 220          * Note: the channel creation op already writes into the packet
 221          * headers. Therefore the "chan" information used as input
 222          * should be already accessible.
 223          */
 224         chan->chan = transport->ops.channel_create("[lttng]", chan, buf_addr,
 225                         subbuf_size, num_subbuf, switch_timer_interval,
 226                         read_timer_interval);
 227         if (!chan->chan)
 228                 goto create_error;
 229         chan->enabled = 1;
 230         chan->ops = &transport->ops;
 231         chan->transport = transport;
 232         list_add(&chan->list, &session->chan);
 233         mutex_unlock(&sessions_mutex);
 234         return chan;
 235
 236 create_error:
 237         kfree(chan);
 238 nomem:
 239         if (transport)
 240                 module_put(transport->owner);
 241 notransport:
 242 active:
 243         mutex_unlock(&sessions_mutex);
 244         return NULL;
 245 }
 246
 247 /*
 248  * Only used internally at session destruction.
 249  */
 250 static
 251 void _ltt_channel_destroy(struct ltt_channel *chan)
 252 {
 253         chan->ops->channel_destroy(chan->chan);
 254         module_put(chan->transport->owner);
 255         list_del(&chan->list);
 256         lttng_destroy_context(chan->ctx);
 257         kfree(chan);
 258 }
 259
 260 /*
 261  * Supports event creation while tracing session is active.
 262  */
 263 struct ltt_event *ltt_event_create(struct ltt_channel *chan,
 264                                    struct lttng_kernel_event *event_param,
 265                                    void *filter)
 266 {
 267         struct ltt_event *event;
 268         int ret;
 269
 270         mutex_lock(&sessions_mutex);
 271         if (chan->free_event_id == -1UL)
 272                 goto full;
 273         /*
 274          * This is O(n^2) (for each event, the loop is called at event
 275          * creation). Might require a hash if we have lots of events.
 276          */
 277         list_for_each_entry(event, &chan->session->events, list)
 278                 if (!strcmp(event->desc->name, event_param->name))
 279                         goto exist;
 280         event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
 281         if (!event)
 282                 goto cache_error;
 283         event->chan = chan;
 284         event->filter = filter;
 285         event->id = chan->free_event_id++;
 286         event->enabled = 1;
 287         event->instrumentation = event_param->instrumentation;
 288         /* Populate ltt_event structure before tracepoint registration. */
 289         smp_wmb();
 290         switch (event_param->instrumentation) {
 291         case LTTNG_KERNEL_TRACEPOINT:
 292                 event->desc = ltt_event_get(event_param->name);
 293                 if (!event->desc)
 294                         goto register_error;
 295                 ret = tracepoint_probe_register(event_param->name,
 296                                 event->desc->probe_callback,
 297                                 event);
 298                 if (ret)
 299                         goto register_error;
 300                 break;
 301         case LTTNG_KERNEL_KPROBE:
 302                 ret = lttng_kprobes_register(event_param->name,
 303                                 event_param->u.kprobe.symbol_name,
 304                                 event_param->u.kprobe.offset,
 305                                 event_param->u.kprobe.addr,
 306                                 event);
 307                 if (ret)
 308                         goto register_error;
 309                 ret = try_module_get(event->desc->owner);
 310                 WARN_ON_ONCE(!ret);
 311                 break;
 312         case LTTNG_KERNEL_FUNCTION:
 313                 ret = lttng_ftrace_register(event_param->name,
 314                                 event_param->u.ftrace.symbol_name,
 315                                 event);
 316                 if (ret)
 317                         goto register_error;
 318                 ret = try_module_get(event->desc->owner);
 319                 WARN_ON_ONCE(!ret);
 320                 break;
 321         default:
 322                 WARN_ON_ONCE(1);
 323         }
 324         ret = _ltt_event_metadata_statedump(chan->session, chan, event);
 325         if (ret)
 326                 goto statedump_error;
 327         list_add(&event->list, &chan->session->events);
 328         mutex_unlock(&sessions_mutex);
 329         return event;
 330
 331 statedump_error:
 332         WARN_ON_ONCE(tracepoint_probe_unregister(event_param->name,
 333                                 event->desc->probe_callback,
 334                                 event));
 335         ltt_event_put(event->desc);
 336 register_error:
 337         kmem_cache_free(event_cache, event);
 338 cache_error:
 339 exist:
 340 full:
 341         mutex_unlock(&sessions_mutex);
 342         return NULL;
 343 }
 344
 345 /*
 346  * Only used internally at session destruction.
 347  */
 348 int _ltt_event_unregister(struct ltt_event *event)
 349 {
 350         int ret = -EINVAL;
 351
 352         switch (event->instrumentation) {
 353         case LTTNG_KERNEL_TRACEPOINT:
 354                 ret = tracepoint_probe_unregister(event->desc->name,
 355                                                   event->desc->probe_callback,
 356                                                   event);
 357                 if (ret)
 358                         return ret;
 359                 break;
 360         case LTTNG_KERNEL_KPROBE:
 361                 lttng_kprobes_unregister(event);
 362                 ret = 0;
 363                 break;
 364         case LTTNG_KERNEL_FUNCTION:
 365                 lttng_ftrace_unregister(event);
 366                 ret = 0;
 367                 break;
 368         default:
 369                 WARN_ON_ONCE(1);
 370         }
 371         return ret;
 372 }
 373
 374 /*
 375  * Only used internally at session destruction.
 376  */
 377 static
 378 void _ltt_event_destroy(struct ltt_event *event)
 379 {
 380         switch (event->instrumentation) {
 381         case LTTNG_KERNEL_TRACEPOINT:
 382                 ltt_event_put(event->desc);
 383                 break;
 384         case LTTNG_KERNEL_KPROBE:
 385                 module_put(event->desc->owner);
 386                 lttng_kprobes_destroy_private(event);
 387                 break;
 388         case LTTNG_KERNEL_FUNCTION:
 389                 module_put(event->desc->owner);
 390                 lttng_ftrace_destroy_private(event);
 391                 break;
 392         default:
 393                 WARN_ON_ONCE(1);
 394         }
 395         list_del(&event->list);
 396         lttng_destroy_context(event->ctx);
 397         kmem_cache_free(event_cache, event);
 398 }
 399
 400 /*
 401  * We have exclusive access to our metadata buffer (protected by the
 402  * sessions_mutex), so we can do racy operations such as looking for
 403  * remaining space left in packet and write, since mutual exclusion
 404  * protects us from concurrent writes.
 405  */
 406 int lttng_metadata_printf(struct ltt_session *session,
 407                           const char *fmt, ...)
 408 {
 409         struct lib_ring_buffer_ctx ctx;
 410         struct ltt_channel *chan = session->metadata;
 411         char *str;
 412         int ret = 0, waitret;
 413         size_t len, reserve_len, pos;
 414         va_list ap;
 415
 416         WARN_ON_ONCE(!ACCESS_ONCE(session->active));
 417
 418         va_start(ap, fmt);
 419         str = kvasprintf(GFP_KERNEL, fmt, ap);
 420         va_end(ap);
 421         if (!str)
 422                 return -ENOMEM;
 423
 424         len = strlen(str);
 425         pos = 0;
 426
 427         for (pos = 0; pos < len; pos += reserve_len) {
 428                 reserve_len = min_t(size_t,
 429                                 chan->ops->packet_avail_size(chan->chan),
 430                                 len - pos);
 431                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 432                                          sizeof(char), -1);
 433                 /*
 434                  * We don't care about metadata buffer's records lost
 435                  * count, because we always retry here. Report error if
 436                  * we need to bail out after timeout or being
 437                  * interrupted.
 438                  */
 439                 waitret = wait_event_interruptible_timeout(*chan->ops->get_reader_wait_queue(chan->chan),
 440                         ({
 441                                 ret = chan->ops->event_reserve(&ctx, 0);
 442                                 ret != -ENOBUFS || !ret;
 443                         }),
 444                         msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC));
 445                 if (!waitret || waitret == -ERESTARTSYS || ret) {
 446                         printk(KERN_WARNING "LTTng: Failure to write metadata to buffers (%s)\n",
 447                                 waitret == -ERESTARTSYS ? "interrupted" :
 448                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 449                         if (waitret == -ERESTARTSYS)
 450                                 ret = waitret;
 451                         goto end;
 452                 }
 453                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 454                 chan->ops->event_commit(&ctx);
 455         }
 456 end:
 457         kfree(str);
 458         return ret;
 459 }
 460
 461 static
 462 int _ltt_field_statedump(struct ltt_session *session,
 463                          const struct lttng_event_field *field)
 464 {
 465         int ret = 0;
 466
 467         switch (field->type.atype) {
 468         case atype_integer:
 469                 ret = lttng_metadata_printf(session,
 470                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s;\n",
 471                         field->type.u.basic.integer.size,
 472                         field->type.u.basic.integer.alignment,
 473                         field->type.u.basic.integer.signedness,
 474                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 475                                 ? "none"
 476                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 477                                         ? "UTF8"
 478                                         : "ASCII",
 479                         field->type.u.basic.integer.base,
 480 #ifdef __BIG_ENDIAN
 481                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 482 #else
 483                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 484 #endif
 485                         field->name);
 486                 break;
 487         case atype_enum:
 488                 ret = lttng_metadata_printf(session,
 489                         "               %s %s;\n",
 490                         field->type.u.basic.enumeration.name,
 491                         field->name);
 492                 break;
 493         case atype_array:
 494         {
 495                 const struct lttng_basic_type *elem_type;
 496
 497                 elem_type = &field->type.u.array.elem_type;
 498                 ret = lttng_metadata_printf(session,
 499                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[%u];\n",
 500                         elem_type->u.basic.integer.size,
 501                         elem_type->u.basic.integer.alignment,
 502                         elem_type->u.basic.integer.signedness,
 503                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 504                                 ? "none"
 505                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 506                                         ? "UTF8"
 507                                         : "ASCII",
 508                         elem_type->u.basic.integer.base,
 509 #ifdef __BIG_ENDIAN
 510                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 511 #else
 512                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 513 #endif
 514                         field->name, field->type.u.array.length);
 515                 break;
 516         }
 517         case atype_sequence:
 518         {
 519                 const struct lttng_basic_type *elem_type;
 520                 const struct lttng_basic_type *length_type;
 521
 522                 elem_type = &field->type.u.sequence.elem_type;
 523                 length_type = &field->type.u.sequence.length_type;
 524                 ret = lttng_metadata_printf(session,
 525                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 526                         length_type->u.basic.integer.size,
 527                         (unsigned int) length_type->u.basic.integer.alignment,
 528                         length_type->u.basic.integer.signedness,
 529                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 530                                 ? "none"
 531                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 532                                         ? "UTF8"
 533                                         : "ASCII"),
 534                         length_type->u.basic.integer.base,
 535 #ifdef __BIG_ENDIAN
 536                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 537 #else
 538                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 539 #endif
 540                         field->name);
 541                 if (ret)
 542                         return ret;
 543
 544                 ret = lttng_metadata_printf(session,
 545                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[ __%s_length ];\n",
 546                         elem_type->u.basic.integer.size,
 547                         (unsigned int) elem_type->u.basic.integer.alignment,
 548                         elem_type->u.basic.integer.signedness,
 549                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 550                                 ? "none"
 551                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 552                                         ? "UTF8"
 553                                         : "ASCII"),
 554                         elem_type->u.basic.integer.base,
 555 #ifdef __BIG_ENDIAN
 556                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 557 #else
 558                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 559 #endif
 560                         field->name,
 561                         field->name);
 562                 break;
 563         }
 564
 565         case atype_string:
 566                 /* Default encoding is UTF8 */
 567                 ret = lttng_metadata_printf(session,
 568                         "               string%s %s;\n",
 569                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 570                                 " { encoding = ASCII; }" : "",
 571                         field->name);
 572                 break;
 573         default:
 574                 WARN_ON_ONCE(1);
 575                 return -EINVAL;
 576         }
 577         return ret;
 578 }
 579
 580 static
 581 int _ltt_context_metadata_statedump(struct ltt_session *session,
 582                                     struct lttng_ctx *ctx)
 583 {
 584         int ret = 0;
 585         int i;
 586
 587         if (!ctx)
 588                 return 0;
 589         for (i = 0; i < ctx->nr_fields; i++) {
 590                 const struct lttng_ctx_field *field = &ctx->fields[i];
 591
 592                 ret = _ltt_field_statedump(session, &field->event_field);
 593                 if (ret)
 594                         return ret;
 595         }
 596         return ret;
 597 }
 598
 599 static
 600 int _ltt_fields_metadata_statedump(struct ltt_session *session,
 601                                    struct ltt_event *event)
 602 {
 603         const struct lttng_event_desc *desc = event->desc;
 604         int ret = 0;
 605         int i;
 606
 607         for (i = 0; i < desc->nr_fields; i++) {
 608                 const struct lttng_event_field *field = &desc->fields[i];
 609
 610                 ret = _ltt_field_statedump(session, field);
 611                 if (ret)
 612                         return ret;
 613         }
 614         return ret;
 615 }
 616
 617 static
 618 int _ltt_event_metadata_statedump(struct ltt_session *session,
 619                                   struct ltt_channel *chan,
 620                                   struct ltt_event *event)
 621 {
 622         int ret = 0;
 623
 624         if (event->metadata_dumped || !ACCESS_ONCE(session->active))
 625                 return 0;
 626         if (chan == session->metadata)
 627                 return 0;
 628
 629         ret = lttng_metadata_printf(session,
 630                 "event {\n"
 631                 "       name = %s;\n"
 632                 "       id = %u;\n"
 633                 "       stream_id = %u;\n",
 634                 event->desc->name,
 635                 event->id,
 636                 event->chan->id);
 637         if (ret)
 638                 goto end;
 639
 640         if (event->ctx) {
 641                 ret = lttng_metadata_printf(session,
 642                         "       context := struct {\n");
 643                 if (ret)
 644                         goto end;
 645         }
 646         ret = _ltt_context_metadata_statedump(session, event->ctx);
 647         if (ret)
 648                 goto end;
 649         if (event->ctx) {
 650                 ret = lttng_metadata_printf(session,
 651                         "       };\n");
 652                 if (ret)
 653                         goto end;
 654         }
 655
 656         ret = lttng_metadata_printf(session,
 657                 "       fields := struct {\n"
 658                 );
 659         if (ret)
 660                 goto end;
 661
 662         ret = _ltt_fields_metadata_statedump(session, event);
 663         if (ret)
 664                 goto end;
 665
 666         /*
 667          * LTTng space reservation can only reserve multiples of the
 668          * byte size.
 669          */
 670         ret = lttng_metadata_printf(session,
 671                 "       };\n"
 672                 "};\n\n");
 673         if (ret)
 674                 goto end;
 675
 676         event->metadata_dumped = 1;
 677 end:
 678         return ret;
 679
 680 }
 681
 682 static
 683 int _ltt_channel_metadata_statedump(struct ltt_session *session,
 684                                     struct ltt_channel *chan)
 685 {
 686         int ret = 0;
 687
 688         if (chan->metadata_dumped || !ACCESS_ONCE(session->active))
 689                 return 0;
 690         if (chan == session->metadata)
 691                 return 0;
 692
 693         WARN_ON_ONCE(!chan->header_type);
 694         ret = lttng_metadata_printf(session,
 695                 "stream {\n"
 696                 "       id = %u;\n"
 697                 "       event.header := %s;\n"
 698                 "       packet.context := struct packet_context;\n",
 699                 chan->id,
 700                 chan->header_type == 1 ? "struct event_header_compact" :
 701                         "struct event_header_large");
 702         if (ret)
 703                 goto end;
 704
 705         if (chan->ctx) {
 706                 ret = lttng_metadata_printf(session,
 707                         "       event.context := struct {\n");
 708                 if (ret)
 709                         goto end;
 710         }
 711         ret = _ltt_context_metadata_statedump(session, chan->ctx);
 712         if (ret)
 713                 goto end;
 714         if (chan->ctx) {
 715                 ret = lttng_metadata_printf(session,
 716                         "       };\n");
 717                 if (ret)
 718                         goto end;
 719         }
 720
 721         ret = lttng_metadata_printf(session,
 722                 "};\n\n");
 723
 724         chan->metadata_dumped = 1;
 725 end:
 726         return ret;
 727 }
 728
 729 static
 730 int _ltt_stream_packet_context_declare(struct ltt_session *session)
 731 {
 732         return lttng_metadata_printf(session,
 733                 "struct packet_context {\n"
 734                 "       uint64_t timestamp_begin;\n"
 735                 "       uint64_t timestamp_end;\n"
 736                 "       uint32_t events_discarded;\n"
 737                 "       uint32_t content_size;\n"
 738                 "       uint32_t packet_size;\n"
 739                 "       uint32_t cpu_id;\n"
 740                 "};\n\n"
 741                 );
 742 }
 743
 744 /*
 745  * Compact header:
 746  * id: range: 0 - 30.
 747  * id 31 is reserved to indicate an extended header.
 748  *
 749  * Large header:
 750  * id: range: 0 - 65534.
 751  * id 65535 is reserved to indicate an extended header.
 752  */
 753 static
 754 int _ltt_event_header_declare(struct ltt_session *session)
 755 {
 756         return lttng_metadata_printf(session,
 757         "struct event_header_compact {\n"
 758         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
 759         "       variant <id> {\n"
 760         "               struct {\n"
 761         "                       uint27_t timestamp;\n"
 762         "               } compact;\n"
 763         "               struct {\n"
 764         "                       uint32_t id;\n"
 765         "                       uint64_t timestamp;\n"
 766         "               } extended;\n"
 767         "       } v;\n"
 768         "} align(%u);\n"
 769         "\n"
 770         "struct event_header_large {\n"
 771         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
 772         "       variant <id> {\n"
 773         "               struct {\n"
 774         "                       uint32_t timestamp;\n"
 775         "               } compact;\n"
 776         "               struct {\n"
 777         "                       uint32_t id;\n"
 778         "                       uint64_t timestamp;\n"
 779         "               } extended;\n"
 780         "       } v;\n"
 781         "} align(%u);\n\n",
 782         ltt_alignof(uint32_t) * CHAR_BIT,
 783         ltt_alignof(uint16_t) * CHAR_BIT
 784         );
 785 }
 786
 787 /*
 788  * Output metadata into this session's metadata buffers.
 789  */
 790 static
 791 int _ltt_session_metadata_statedump(struct ltt_session *session)
 792 {
 793         unsigned char *uuid_c = session->uuid.b;
 794         unsigned char uuid_s[37];
 795         struct ltt_channel *chan;
 796         struct ltt_event *event;
 797         int ret = 0;
 798
 799         if (!ACCESS_ONCE(session->active))
 800                 return 0;
 801         if (session->metadata_dumped)
 802                 goto skip_session;
 803         if (!session->metadata) {
 804                 printk(KERN_WARNING "LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
 805                 return -EPERM;
 806         }
 807
 808         snprintf(uuid_s, sizeof(uuid_s),
 809                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 810                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
 811                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
 812                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
 813                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
 814
 815         ret = lttng_metadata_printf(session,
 816                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
 817                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
 818                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
 819                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
 820                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
 821                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
 822                 "\n"
 823                 "trace {\n"
 824                 "       major = %u;\n"
 825                 "       minor = %u;\n"
 826                 "       uuid = \"%s\";\n"
 827                 "       byte_order = %s;\n"
 828                 "       packet.header := struct {\n"
 829                 "               uint32_t magic;\n"
 830                 "               uint8_t  uuid[16];\n"
 831                 "               uint32_t stream_id;\n"
 832                 "       };\n"
 833                 "};\n\n",
 834                 ltt_alignof(uint8_t) * CHAR_BIT,
 835                 ltt_alignof(uint16_t) * CHAR_BIT,
 836                 ltt_alignof(uint32_t) * CHAR_BIT,
 837                 ltt_alignof(uint64_t) * CHAR_BIT,
 838                 CTF_VERSION_MAJOR,
 839                 CTF_VERSION_MINOR,
 840                 uuid_s,
 841 #ifdef __BIG_ENDIAN
 842                 "be"
 843 #else
 844                 "le"
 845 #endif
 846                 );
 847         if (ret)
 848                 goto end;
 849
 850         ret = _ltt_stream_packet_context_declare(session);
 851         if (ret)
 852                 goto end;
 853
 854         ret = _ltt_event_header_declare(session);
 855         if (ret)
 856                 goto end;
 857
 858 skip_session:
 859         list_for_each_entry(chan, &session->chan, list) {
 860                 ret = _ltt_channel_metadata_statedump(session, chan);
 861                 if (ret)
 862                         goto end;
 863         }
 864
 865         list_for_each_entry(event, &session->events, list) {
 866                 ret = _ltt_event_metadata_statedump(session, event->chan, event);
 867                 if (ret)
 868                         goto end;
 869         }
 870         session->metadata_dumped = 1;
 871 end:
 872         return ret;
 873 }
 874
 875 /**
 876  * ltt_transport_register - LTT transport registration
 877  * @transport: transport structure
 878  *
 879  * Registers a transport which can be used as output to extract the data out of
 880  * LTTng. The module calling this registration function must ensure that no
 881  * trap-inducing code will be executed by the transport functions. E.g.
 882  * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
 883  * is made visible to the transport function. This registration acts as a
 884  * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
 885  * after its registration must it synchronize the TLBs.
 886  */
 887 void ltt_transport_register(struct ltt_transport *transport)
 888 {
 889         /*
 890          * Make sure no page fault can be triggered by the module about to be
 891          * registered. We deal with this here so we don't have to call
 892          * vmalloc_sync_all() in each module's init.
 893          */
 894         wrapper_vmalloc_sync_all();
 895
 896         mutex_lock(&sessions_mutex);
 897         list_add_tail(&transport->node, &ltt_transport_list);
 898         mutex_unlock(&sessions_mutex);
 899 }
 900 EXPORT_SYMBOL_GPL(ltt_transport_register);
 901
 902 /**
 903  * ltt_transport_unregister - LTT transport unregistration
 904  * @transport: transport structure
 905  */
 906 void ltt_transport_unregister(struct ltt_transport *transport)
 907 {
 908         mutex_lock(&sessions_mutex);
 909         list_del(&transport->node);
 910         mutex_unlock(&sessions_mutex);
 911 }
 912 EXPORT_SYMBOL_GPL(ltt_transport_unregister);
 913
 914 static int __init ltt_events_init(void)
 915 {
 916         int ret;
 917
 918         event_cache = KMEM_CACHE(ltt_event, 0);
 919         if (!event_cache)
 920                 return -ENOMEM;
 921         ret = ltt_debugfs_abi_init();
 922         if (ret)
 923                 goto error_abi;
 924         return 0;
 925 error_abi:
 926         kmem_cache_destroy(event_cache);
 927         return ret;
 928 }
 929
 930 module_init(ltt_events_init);
 931
 932 static void __exit ltt_events_exit(void)
 933 {
 934         struct ltt_session *session, *tmpsession;
 935
 936         ltt_debugfs_abi_exit();
 937         list_for_each_entry_safe(session, tmpsession, &sessions, list)
 938                 ltt_session_destroy(session);
 939         kmem_cache_destroy(event_cache);
 940 }
 941
 942 module_exit(ltt_events_exit);
 943
 944 MODULE_LICENSE("GPL and additional rights");
 945 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 946 MODULE_DESCRIPTION("LTTng Events");