lttng-events.c

   1 /*
   2  * lttng-events.c
   3  *
   4  * Copyright 2010-2011 (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 "lttng-events.h"
  20 #include "lttng-tracer.h"
  21
  22 static LIST_HEAD(sessions);
  23 static LIST_HEAD(lttng_transport_list);
  24 static DEFINE_MUTEX(sessions_mutex);
  25 static struct kmem_cache *event_cache;
  26
  27 static void _lttng_event_destroy(struct lttng_event *event);
  28 static void _lttng_channel_destroy(struct lttng_channel *chan);
  29 static int _lttng_event_unregister(struct lttng_event *event);
  30 static
  31 int _lttng_event_metadata_statedump(struct lttng_session *session,
  32                                   struct lttng_channel *chan,
  33                                   struct lttng_event *event);
  34 static
  35 int _lttng_session_metadata_statedump(struct lttng_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 lttng_session *lttng_session_create(void)
  46 {
  47         struct lttng_session *session;
  48
  49         mutex_lock(&sessions_mutex);
  50         session = kzalloc(sizeof(struct lttng_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 lttng_session_destroy(struct lttng_session *session)
  62 {
  63         struct lttng_channel *chan, *tmpchan;
  64         struct lttng_event *event, *tmpevent;
  65         int ret;
  66
  67         mutex_lock(&sessions_mutex);
  68         ACCESS_ONCE(session->active) = 0;
  69         list_for_each_entry(chan, &session->chan, list) {
  70                 ret = lttng_syscalls_unregister(chan);
  71                 WARN_ON(ret);
  72         }
  73         list_for_each_entry(event, &session->events, list) {
  74                 ret = _lttng_event_unregister(event);
  75                 WARN_ON(ret);
  76         }
  77         synchronize_trace();    /* Wait for in-flight events to complete */
  78         list_for_each_entry_safe(event, tmpevent, &session->events, list)
  79                 _lttng_event_destroy(event);
  80         list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
  81                 _lttng_channel_destroy(chan);
  82         list_del(&session->list);
  83         mutex_unlock(&sessions_mutex);
  84         kfree(session);
  85 }
  86
  87 int lttng_session_enable(struct lttng_session *session)
  88 {
  89         int ret = 0;
  90         struct lttng_channel *chan;
  91
  92         mutex_lock(&sessions_mutex);
  93         if (session->active) {
  94                 ret = -EBUSY;
  95                 goto end;
  96         }
  97
  98         /*
  99          * Snapshot the number of events per channel to know the type of header
 100          * we need to use.
 101          */
 102         list_for_each_entry(chan, &session->chan, list) {
 103                 if (chan->header_type)
 104                         continue;               /* don't change it if session stop/restart */
 105                 if (chan->free_event_id < 31)
 106                         chan->header_type = 1;  /* compact */
 107                 else
 108                         chan->header_type = 2;  /* large */
 109         }
 110
 111         ACCESS_ONCE(session->active) = 1;
 112         ACCESS_ONCE(session->been_active) = 1;
 113         ret = _lttng_session_metadata_statedump(session);
 114         if (ret)
 115                 ACCESS_ONCE(session->active) = 0;
 116 end:
 117         mutex_unlock(&sessions_mutex);
 118         return ret;
 119 }
 120
 121 int lttng_session_disable(struct lttng_session *session)
 122 {
 123         int ret = 0;
 124
 125         mutex_lock(&sessions_mutex);
 126         if (!session->active) {
 127                 ret = -EBUSY;
 128                 goto end;
 129         }
 130         ACCESS_ONCE(session->active) = 0;
 131 end:
 132         mutex_unlock(&sessions_mutex);
 133         return ret;
 134 }
 135
 136 int lttng_channel_enable(struct lttng_channel *channel)
 137 {
 138         int old;
 139
 140         if (channel == channel->session->metadata)
 141                 return -EPERM;
 142         old = xchg(&channel->enabled, 1);
 143         if (old)
 144                 return -EEXIST;
 145         return 0;
 146 }
 147
 148 int lttng_channel_disable(struct lttng_channel *channel)
 149 {
 150         int old;
 151
 152         if (channel == channel->session->metadata)
 153                 return -EPERM;
 154         old = xchg(&channel->enabled, 0);
 155         if (!old)
 156                 return -EEXIST;
 157         return 0;
 158 }
 159
 160 int lttng_event_enable(struct lttng_event *event)
 161 {
 162         int old;
 163
 164         if (event->chan == event->chan->session->metadata)
 165                 return -EPERM;
 166         old = xchg(&event->enabled, 1);
 167         if (old)
 168                 return -EEXIST;
 169         return 0;
 170 }
 171
 172 int lttng_event_disable(struct lttng_event *event)
 173 {
 174         int old;
 175
 176         if (event->chan == event->chan->session->metadata)
 177                 return -EPERM;
 178         old = xchg(&event->enabled, 0);
 179         if (!old)
 180                 return -EEXIST;
 181         return 0;
 182 }
 183
 184 static struct lttng_transport *lttng_transport_find(const char *name)
 185 {
 186         struct lttng_transport *transport;
 187
 188         list_for_each_entry(transport, &lttng_transport_list, node) {
 189                 if (!strcmp(transport->name, name))
 190                         return transport;
 191         }
 192         return NULL;
 193 }
 194
 195 struct lttng_channel *lttng_channel_create(struct lttng_session *session,
 196                                        const char *transport_name,
 197                                        void *buf_addr,
 198                                        size_t subbuf_size, size_t num_subbuf,
 199                                        unsigned int switch_timer_interval,
 200                                        unsigned int read_timer_interval)
 201 {
 202         struct lttng_channel *chan;
 203         struct lttng_transport *transport = NULL;
 204
 205         mutex_lock(&sessions_mutex);
 206         if (session->been_active)
 207                 goto active;    /* Refuse to add channel to active session */
 208         transport = lttng_transport_find(transport_name);
 209         if (!transport) {
 210                 printk(KERN_WARNING "LTTng transport %s not found\n",
 211                        transport_name);
 212                 goto notransport;
 213         }
 214         if (!try_module_get(transport->owner)) {
 215                 printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 216                 goto notransport;
 217         }
 218         chan = kzalloc(sizeof(struct lttng_channel), GFP_KERNEL);
 219         if (!chan)
 220                 goto nomem;
 221         chan->session = session;
 222         chan->id = session->free_chan_id++;
 223         /*
 224          * Note: the channel creation op already writes into the packet
 225          * headers. Therefore the "chan" information used as input
 226          * should be already accessible.
 227          */
 228         chan->chan = transport->ops.channel_create("[lttng]", chan, buf_addr,
 229                         subbuf_size, num_subbuf, switch_timer_interval,
 230                         read_timer_interval);
 231         if (!chan->chan)
 232                 goto create_error;
 233         chan->enabled = 1;
 234         chan->ops = &transport->ops;
 235         chan->transport = transport;
 236         list_add(&chan->list, &session->chan);
 237         mutex_unlock(&sessions_mutex);
 238         return chan;
 239
 240 create_error:
 241         kfree(chan);
 242 nomem:
 243         if (transport)
 244                 module_put(transport->owner);
 245 notransport:
 246 active:
 247         mutex_unlock(&sessions_mutex);
 248         return NULL;
 249 }
 250
 251 /*
 252  * Only used internally at session destruction.
 253  */
 254 static
 255 void _lttng_channel_destroy(struct lttng_channel *chan)
 256 {
 257         chan->ops->channel_destroy(chan->chan);
 258         module_put(chan->transport->owner);
 259         list_del(&chan->list);
 260         lttng_destroy_context(chan->ctx);
 261         kfree(chan);
 262 }
 263
 264 /*
 265  * Supports event creation while tracing session is active.
 266  */
 267 struct lttng_event *lttng_event_create(struct lttng_channel *chan,
 268                                    struct lttng_kernel_event *event_param,
 269                                    void *filter,
 270                                    const struct lttng_event_desc *internal_desc)
 271 {
 272         struct lttng_event *event;
 273         int ret;
 274
 275         mutex_lock(&sessions_mutex);
 276         if (chan->free_event_id == -1UL)
 277                 goto full;
 278         /*
 279          * This is O(n^2) (for each event, the loop is called at event
 280          * creation). Might require a hash if we have lots of events.
 281          */
 282         list_for_each_entry(event, &chan->session->events, list)
 283                 if (!strcmp(event->desc->name, event_param->name))
 284                         goto exist;
 285         event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
 286         if (!event)
 287                 goto cache_error;
 288         event->chan = chan;
 289         event->filter = filter;
 290         event->id = chan->free_event_id++;
 291         event->enabled = 1;
 292         event->instrumentation = event_param->instrumentation;
 293         /* Populate lttng_event structure before tracepoint registration. */
 294         smp_wmb();
 295         switch (event_param->instrumentation) {
 296         case LTTNG_KERNEL_TRACEPOINT:
 297                 event->desc = lttng_event_get(event_param->name);
 298                 if (!event->desc)
 299                         goto register_error;
 300                 ret = tracepoint_probe_register(event_param->name,
 301                                 event->desc->probe_callback,
 302                                 event);
 303                 if (ret)
 304                         goto register_error;
 305                 break;
 306         case LTTNG_KERNEL_KPROBE:
 307                 ret = lttng_kprobes_register(event_param->name,
 308                                 event_param->u.kprobe.symbol_name,
 309                                 event_param->u.kprobe.offset,
 310                                 event_param->u.kprobe.addr,
 311                                 event);
 312                 if (ret)
 313                         goto register_error;
 314                 ret = try_module_get(event->desc->owner);
 315                 WARN_ON_ONCE(!ret);
 316                 break;
 317         case LTTNG_KERNEL_KRETPROBE:
 318         {
 319                 struct lttng_event *event_return;
 320
 321                 /* kretprobe defines 2 events */
 322                 event_return =
 323                         kmem_cache_zalloc(event_cache, GFP_KERNEL);
 324                 if (!event_return)
 325                         goto register_error;
 326                 event_return->chan = chan;
 327                 event_return->filter = filter;
 328                 event_return->id = chan->free_event_id++;
 329                 event_return->enabled = 1;
 330                 event_return->instrumentation = event_param->instrumentation;
 331                 /*
 332                  * Populate lttng_event structure before kretprobe registration.
 333                  */
 334                 smp_wmb();
 335                 ret = lttng_kretprobes_register(event_param->name,
 336                                 event_param->u.kretprobe.symbol_name,
 337                                 event_param->u.kretprobe.offset,
 338                                 event_param->u.kretprobe.addr,
 339                                 event, event_return);
 340                 if (ret) {
 341                         kmem_cache_free(event_cache, event_return);
 342                         goto register_error;
 343                 }
 344                 /* Take 2 refs on the module: one per event. */
 345                 ret = try_module_get(event->desc->owner);
 346                 WARN_ON_ONCE(!ret);
 347                 ret = try_module_get(event->desc->owner);
 348                 WARN_ON_ONCE(!ret);
 349                 ret = _lttng_event_metadata_statedump(chan->session, chan,
 350                                                     event_return);
 351                 if (ret) {
 352                         kmem_cache_free(event_cache, event_return);
 353                         module_put(event->desc->owner);
 354                         module_put(event->desc->owner);
 355                         goto statedump_error;
 356                 }
 357                 list_add(&event_return->list, &chan->session->events);
 358                 break;
 359         }
 360         case LTTNG_KERNEL_FUNCTION:
 361                 ret = lttng_ftrace_register(event_param->name,
 362                                 event_param->u.ftrace.symbol_name,
 363                                 event);
 364                 if (ret)
 365                         goto register_error;
 366                 ret = try_module_get(event->desc->owner);
 367                 WARN_ON_ONCE(!ret);
 368                 break;
 369         case LTTNG_KERNEL_NOOP:
 370                 event->desc = internal_desc;
 371                 if (!event->desc)
 372                         goto register_error;
 373                 break;
 374         default:
 375                 WARN_ON_ONCE(1);
 376         }
 377         ret = _lttng_event_metadata_statedump(chan->session, chan, event);
 378         if (ret)
 379                 goto statedump_error;
 380         list_add(&event->list, &chan->session->events);
 381         mutex_unlock(&sessions_mutex);
 382         return event;
 383
 384 statedump_error:
 385         /* If a statedump error occurs, events will not be readable. */
 386 register_error:
 387         kmem_cache_free(event_cache, event);
 388 cache_error:
 389 exist:
 390 full:
 391         mutex_unlock(&sessions_mutex);
 392         return NULL;
 393 }
 394
 395 /*
 396  * Only used internally at session destruction.
 397  */
 398 int _lttng_event_unregister(struct lttng_event *event)
 399 {
 400         int ret = -EINVAL;
 401
 402         switch (event->instrumentation) {
 403         case LTTNG_KERNEL_TRACEPOINT:
 404                 ret = tracepoint_probe_unregister(event->desc->name,
 405                                                   event->desc->probe_callback,
 406                                                   event);
 407                 if (ret)
 408                         return ret;
 409                 break;
 410         case LTTNG_KERNEL_KPROBE:
 411                 lttng_kprobes_unregister(event);
 412                 ret = 0;
 413                 break;
 414         case LTTNG_KERNEL_KRETPROBE:
 415                 lttng_kretprobes_unregister(event);
 416                 ret = 0;
 417                 break;
 418         case LTTNG_KERNEL_FUNCTION:
 419                 lttng_ftrace_unregister(event);
 420                 ret = 0;
 421                 break;
 422         case LTTNG_KERNEL_NOOP:
 423                 ret = 0;
 424                 break;
 425         default:
 426                 WARN_ON_ONCE(1);
 427         }
 428         return ret;
 429 }
 430
 431 /*
 432  * Only used internally at session destruction.
 433  */
 434 static
 435 void _lttng_event_destroy(struct lttng_event *event)
 436 {
 437         switch (event->instrumentation) {
 438         case LTTNG_KERNEL_TRACEPOINT:
 439                 lttng_event_put(event->desc);
 440                 break;
 441         case LTTNG_KERNEL_KPROBE:
 442                 module_put(event->desc->owner);
 443                 lttng_kprobes_destroy_private(event);
 444                 break;
 445         case LTTNG_KERNEL_KRETPROBE:
 446                 module_put(event->desc->owner);
 447                 lttng_kretprobes_destroy_private(event);
 448                 break;
 449         case LTTNG_KERNEL_FUNCTION:
 450                 module_put(event->desc->owner);
 451                 lttng_ftrace_destroy_private(event);
 452                 break;
 453         case LTTNG_KERNEL_NOOP:
 454                 break;
 455         default:
 456                 WARN_ON_ONCE(1);
 457         }
 458         list_del(&event->list);
 459         lttng_destroy_context(event->ctx);
 460         kmem_cache_free(event_cache, event);
 461 }
 462
 463 /*
 464  * We have exclusive access to our metadata buffer (protected by the
 465  * sessions_mutex), so we can do racy operations such as looking for
 466  * remaining space left in packet and write, since mutual exclusion
 467  * protects us from concurrent writes.
 468  */
 469 int lttng_metadata_printf(struct lttng_session *session,
 470                           const char *fmt, ...)
 471 {
 472         struct lib_ring_buffer_ctx ctx;
 473         struct lttng_channel *chan = session->metadata;
 474         char *str;
 475         int ret = 0, waitret;
 476         size_t len, reserve_len, pos;
 477         va_list ap;
 478
 479         WARN_ON_ONCE(!ACCESS_ONCE(session->active));
 480
 481         va_start(ap, fmt);
 482         str = kvasprintf(GFP_KERNEL, fmt, ap);
 483         va_end(ap);
 484         if (!str)
 485                 return -ENOMEM;
 486
 487         len = strlen(str);
 488         pos = 0;
 489
 490         for (pos = 0; pos < len; pos += reserve_len) {
 491                 reserve_len = min_t(size_t,
 492                                 chan->ops->packet_avail_size(chan->chan),
 493                                 len - pos);
 494                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 495                                          sizeof(char), -1);
 496                 /*
 497                  * We don't care about metadata buffer's records lost
 498                  * count, because we always retry here. Report error if
 499                  * we need to bail out after timeout or being
 500                  * interrupted.
 501                  */
 502                 waitret = wait_event_interruptible_timeout(*chan->ops->get_writer_buf_wait_queue(chan->chan, -1),
 503                         ({
 504                                 ret = chan->ops->event_reserve(&ctx, 0);
 505                                 ret != -ENOBUFS || !ret;
 506                         }),
 507                         msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC));
 508                 if (!waitret || waitret == -ERESTARTSYS || ret) {
 509                         printk(KERN_WARNING "LTTng: Failure to write metadata to buffers (%s)\n",
 510                                 waitret == -ERESTARTSYS ? "interrupted" :
 511                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 512                         if (waitret == -ERESTARTSYS)
 513                                 ret = waitret;
 514                         goto end;
 515                 }
 516                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 517                 chan->ops->event_commit(&ctx);
 518         }
 519 end:
 520         kfree(str);
 521         return ret;
 522 }
 523
 524 static
 525 int _lttng_field_statedump(struct lttng_session *session,
 526                          const struct lttng_event_field *field)
 527 {
 528         int ret = 0;
 529
 530         switch (field->type.atype) {
 531         case atype_integer:
 532                 ret = lttng_metadata_printf(session,
 533                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 534                         field->type.u.basic.integer.size,
 535                         field->type.u.basic.integer.alignment,
 536                         field->type.u.basic.integer.signedness,
 537                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 538                                 ? "none"
 539                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 540                                         ? "UTF8"
 541                                         : "ASCII",
 542                         field->type.u.basic.integer.base,
 543 #ifdef __BIG_ENDIAN
 544                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 545 #else
 546                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 547 #endif
 548                         field->name);
 549                 break;
 550         case atype_enum:
 551                 ret = lttng_metadata_printf(session,
 552                         "               %s _%s;\n",
 553                         field->type.u.basic.enumeration.name,
 554                         field->name);
 555                 break;
 556         case atype_array:
 557         {
 558                 const struct lttng_basic_type *elem_type;
 559
 560                 elem_type = &field->type.u.array.elem_type;
 561                 ret = lttng_metadata_printf(session,
 562                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 563                         elem_type->u.basic.integer.size,
 564                         elem_type->u.basic.integer.alignment,
 565                         elem_type->u.basic.integer.signedness,
 566                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 567                                 ? "none"
 568                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 569                                         ? "UTF8"
 570                                         : "ASCII",
 571                         elem_type->u.basic.integer.base,
 572 #ifdef __BIG_ENDIAN
 573                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 574 #else
 575                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 576 #endif
 577                         field->name, field->type.u.array.length);
 578                 break;
 579         }
 580         case atype_sequence:
 581         {
 582                 const struct lttng_basic_type *elem_type;
 583                 const struct lttng_basic_type *length_type;
 584
 585                 elem_type = &field->type.u.sequence.elem_type;
 586                 length_type = &field->type.u.sequence.length_type;
 587                 ret = lttng_metadata_printf(session,
 588                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 589                         length_type->u.basic.integer.size,
 590                         (unsigned int) length_type->u.basic.integer.alignment,
 591                         length_type->u.basic.integer.signedness,
 592                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 593                                 ? "none"
 594                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 595                                         ? "UTF8"
 596                                         : "ASCII"),
 597                         length_type->u.basic.integer.base,
 598 #ifdef __BIG_ENDIAN
 599                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 600 #else
 601                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 602 #endif
 603                         field->name);
 604                 if (ret)
 605                         return ret;
 606
 607                 ret = lttng_metadata_printf(session,
 608                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 609                         elem_type->u.basic.integer.size,
 610                         (unsigned int) elem_type->u.basic.integer.alignment,
 611                         elem_type->u.basic.integer.signedness,
 612                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 613                                 ? "none"
 614                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 615                                         ? "UTF8"
 616                                         : "ASCII"),
 617                         elem_type->u.basic.integer.base,
 618 #ifdef __BIG_ENDIAN
 619                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 620 #else
 621                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 622 #endif
 623                         field->name,
 624                         field->name);
 625                 break;
 626         }
 627
 628         case atype_string:
 629                 /* Default encoding is UTF8 */
 630                 ret = lttng_metadata_printf(session,
 631                         "               string%s _%s;\n",
 632                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 633                                 " { encoding = ASCII; }" : "",
 634                         field->name);
 635                 break;
 636         default:
 637                 WARN_ON_ONCE(1);
 638                 return -EINVAL;
 639         }
 640         return ret;
 641 }
 642
 643 static
 644 int _lttng_context_metadata_statedump(struct lttng_session *session,
 645                                     struct lttng_ctx *ctx)
 646 {
 647         int ret = 0;
 648         int i;
 649
 650         if (!ctx)
 651                 return 0;
 652         for (i = 0; i < ctx->nr_fields; i++) {
 653                 const struct lttng_ctx_field *field = &ctx->fields[i];
 654
 655                 ret = _lttng_field_statedump(session, &field->event_field);
 656                 if (ret)
 657                         return ret;
 658         }
 659         return ret;
 660 }
 661
 662 static
 663 int _lttng_fields_metadata_statedump(struct lttng_session *session,
 664                                    struct lttng_event *event)
 665 {
 666         const struct lttng_event_desc *desc = event->desc;
 667         int ret = 0;
 668         int i;
 669
 670         for (i = 0; i < desc->nr_fields; i++) {
 671                 const struct lttng_event_field *field = &desc->fields[i];
 672
 673                 ret = _lttng_field_statedump(session, field);
 674                 if (ret)
 675                         return ret;
 676         }
 677         return ret;
 678 }
 679
 680 static
 681 int _lttng_event_metadata_statedump(struct lttng_session *session,
 682                                   struct lttng_channel *chan,
 683                                   struct lttng_event *event)
 684 {
 685         int ret = 0;
 686
 687         if (event->metadata_dumped || !ACCESS_ONCE(session->active))
 688                 return 0;
 689         if (chan == session->metadata)
 690                 return 0;
 691
 692         ret = lttng_metadata_printf(session,
 693                 "event {\n"
 694                 "       name = %s;\n"
 695                 "       id = %u;\n"
 696                 "       stream_id = %u;\n",
 697                 event->desc->name,
 698                 event->id,
 699                 event->chan->id);
 700         if (ret)
 701                 goto end;
 702
 703         if (event->ctx) {
 704                 ret = lttng_metadata_printf(session,
 705                         "       context := struct {\n");
 706                 if (ret)
 707                         goto end;
 708         }
 709         ret = _lttng_context_metadata_statedump(session, event->ctx);
 710         if (ret)
 711                 goto end;
 712         if (event->ctx) {
 713                 ret = lttng_metadata_printf(session,
 714                         "       };\n");
 715                 if (ret)
 716                         goto end;
 717         }
 718
 719         ret = lttng_metadata_printf(session,
 720                 "       fields := struct {\n"
 721                 );
 722         if (ret)
 723                 goto end;
 724
 725         ret = _lttng_fields_metadata_statedump(session, event);
 726         if (ret)
 727                 goto end;
 728
 729         /*
 730          * LTTng space reservation can only reserve multiples of the
 731          * byte size.
 732          */
 733         ret = lttng_metadata_printf(session,
 734                 "       };\n"
 735                 "};\n\n");
 736         if (ret)
 737                 goto end;
 738
 739         event->metadata_dumped = 1;
 740 end:
 741         return ret;
 742
 743 }
 744
 745 static
 746 int _lttng_channel_metadata_statedump(struct lttng_session *session,
 747                                     struct lttng_channel *chan)
 748 {
 749         int ret = 0;
 750
 751         if (chan->metadata_dumped || !ACCESS_ONCE(session->active))
 752                 return 0;
 753         if (chan == session->metadata)
 754                 return 0;
 755
 756         WARN_ON_ONCE(!chan->header_type);
 757         ret = lttng_metadata_printf(session,
 758                 "stream {\n"
 759                 "       id = %u;\n"
 760                 "       event.header := %s;\n"
 761                 "       packet.context := struct packet_context;\n",
 762                 chan->id,
 763                 chan->header_type == 1 ? "struct event_header_compact" :
 764                         "struct event_header_large");
 765         if (ret)
 766                 goto end;
 767
 768         if (chan->ctx) {
 769                 ret = lttng_metadata_printf(session,
 770                         "       event.context := struct {\n");
 771                 if (ret)
 772                         goto end;
 773         }
 774         ret = _lttng_context_metadata_statedump(session, chan->ctx);
 775         if (ret)
 776                 goto end;
 777         if (chan->ctx) {
 778                 ret = lttng_metadata_printf(session,
 779                         "       };\n");
 780                 if (ret)
 781                         goto end;
 782         }
 783
 784         ret = lttng_metadata_printf(session,
 785                 "};\n\n");
 786
 787         chan->metadata_dumped = 1;
 788 end:
 789         return ret;
 790 }
 791
 792 static
 793 int _lttng_stream_packet_context_declare(struct lttng_session *session)
 794 {
 795         return lttng_metadata_printf(session,
 796                 "struct packet_context {\n"
 797                 "       uint64_t timestamp_begin;\n"
 798                 "       uint64_t timestamp_end;\n"
 799                 "       uint32_t events_discarded;\n"
 800                 "       uint32_t content_size;\n"
 801                 "       uint32_t packet_size;\n"
 802                 "       uint32_t cpu_id;\n"
 803                 "};\n\n"
 804                 );
 805 }
 806
 807 /*
 808  * Compact header:
 809  * id: range: 0 - 30.
 810  * id 31 is reserved to indicate an extended header.
 811  *
 812  * Large header:
 813  * id: range: 0 - 65534.
 814  * id 65535 is reserved to indicate an extended header.
 815  */
 816 static
 817 int _lttng_event_header_declare(struct lttng_session *session)
 818 {
 819         return lttng_metadata_printf(session,
 820         "struct event_header_compact {\n"
 821         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
 822         "       variant <id> {\n"
 823         "               struct {\n"
 824         "                       uint27_t timestamp;\n"
 825         "               } compact;\n"
 826         "               struct {\n"
 827         "                       uint32_t id;\n"
 828         "                       uint64_t timestamp;\n"
 829         "               } extended;\n"
 830         "       } v;\n"
 831         "} align(%u);\n"
 832         "\n"
 833         "struct event_header_large {\n"
 834         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
 835         "       variant <id> {\n"
 836         "               struct {\n"
 837         "                       uint32_t timestamp;\n"
 838         "               } compact;\n"
 839         "               struct {\n"
 840         "                       uint32_t id;\n"
 841         "                       uint64_t timestamp;\n"
 842         "               } extended;\n"
 843         "       } v;\n"
 844         "} align(%u);\n\n",
 845         lttng_alignof(uint32_t) * CHAR_BIT,
 846         lttng_alignof(uint16_t) * CHAR_BIT
 847         );
 848 }
 849
 850 /*
 851  * Output metadata into this session's metadata buffers.
 852  */
 853 static
 854 int _lttng_session_metadata_statedump(struct lttng_session *session)
 855 {
 856         unsigned char *uuid_c = session->uuid.b;
 857         unsigned char uuid_s[37];
 858         struct lttng_channel *chan;
 859         struct lttng_event *event;
 860         int ret = 0;
 861
 862         if (!ACCESS_ONCE(session->active))
 863                 return 0;
 864         if (session->metadata_dumped)
 865                 goto skip_session;
 866         if (!session->metadata) {
 867                 printk(KERN_WARNING "LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
 868                 return -EPERM;
 869         }
 870
 871         snprintf(uuid_s, sizeof(uuid_s),
 872                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 873                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
 874                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
 875                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
 876                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
 877
 878         ret = lttng_metadata_printf(session,
 879                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
 880                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
 881                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
 882                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
 883                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
 884                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
 885                 "\n"
 886                 "trace {\n"
 887                 "       major = %u;\n"
 888                 "       minor = %u;\n"
 889                 "       uuid = \"%s\";\n"
 890                 "       byte_order = %s;\n"
 891                 "       packet.header := struct {\n"
 892                 "               uint32_t magic;\n"
 893                 "               uint8_t  uuid[16];\n"
 894                 "               uint32_t stream_id;\n"
 895                 "       };\n"
 896                 "};\n\n",
 897                 lttng_alignof(uint8_t) * CHAR_BIT,
 898                 lttng_alignof(uint16_t) * CHAR_BIT,
 899                 lttng_alignof(uint32_t) * CHAR_BIT,
 900                 lttng_alignof(uint64_t) * CHAR_BIT,
 901                 CTF_VERSION_MAJOR,
 902                 CTF_VERSION_MINOR,
 903                 uuid_s,
 904 #ifdef __BIG_ENDIAN
 905                 "be"
 906 #else
 907                 "le"
 908 #endif
 909                 );
 910         if (ret)
 911                 goto end;
 912
 913         ret = _lttng_stream_packet_context_declare(session);
 914         if (ret)
 915                 goto end;
 916
 917         ret = _lttng_event_header_declare(session);
 918         if (ret)
 919                 goto end;
 920
 921 skip_session:
 922         list_for_each_entry(chan, &session->chan, list) {
 923                 ret = _lttng_channel_metadata_statedump(session, chan);
 924                 if (ret)
 925                         goto end;
 926         }
 927
 928         list_for_each_entry(event, &session->events, list) {
 929                 ret = _lttng_event_metadata_statedump(session, event->chan, event);
 930                 if (ret)
 931                         goto end;
 932         }
 933         session->metadata_dumped = 1;
 934 end:
 935         return ret;
 936 }
 937
 938 /**
 939  * lttng_transport_register - LTT transport registration
 940  * @transport: transport structure
 941  *
 942  * Registers a transport which can be used as output to extract the data out of
 943  * LTTng. The module calling this registration function must ensure that no
 944  * trap-inducing code will be executed by the transport functions. E.g.
 945  * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
 946  * is made visible to the transport function. This registration acts as a
 947  * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
 948  * after its registration must it synchronize the TLBs.
 949  */
 950 void lttng_transport_register(struct lttng_transport *transport)
 951 {
 952         /*
 953          * Make sure no page fault can be triggered by the module about to be
 954          * registered. We deal with this here so we don't have to call
 955          * vmalloc_sync_all() in each module's init.
 956          */
 957         wrapper_vmalloc_sync_all();
 958
 959         mutex_lock(&sessions_mutex);
 960         list_add_tail(&transport->node, &lttng_transport_list);
 961         mutex_unlock(&sessions_mutex);
 962 }
 963 EXPORT_SYMBOL_GPL(lttng_transport_register);
 964
 965 /**
 966  * lttng_transport_unregister - LTT transport unregistration
 967  * @transport: transport structure
 968  */
 969 void lttng_transport_unregister(struct lttng_transport *transport)
 970 {
 971         mutex_lock(&sessions_mutex);
 972         list_del(&transport->node);
 973         mutex_unlock(&sessions_mutex);
 974 }
 975 EXPORT_SYMBOL_GPL(lttng_transport_unregister);
 976
 977 static int __init lttng_events_init(void)
 978 {
 979         int ret;
 980
 981         event_cache = KMEM_CACHE(lttng_event, 0);
 982         if (!event_cache)
 983                 return -ENOMEM;
 984         ret = lttng_abi_init();
 985         if (ret)
 986                 goto error_abi;
 987         return 0;
 988 error_abi:
 989         kmem_cache_destroy(event_cache);
 990         return ret;
 991 }
 992
 993 module_init(lttng_events_init);
 994
 995 static void __exit lttng_events_exit(void)
 996 {
 997         struct lttng_session *session, *tmpsession;
 998
 999         lttng_abi_exit();
1000         list_for_each_entry_safe(session, tmpsession, &sessions, list)
1001                 lttng_session_destroy(session);
1002         kmem_cache_destroy(event_cache);
1003 }
1004
1005 module_exit(lttng_events_exit);
1006
1007 MODULE_LICENSE("GPL and additional rights");
1008 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1009 MODULE_DESCRIPTION("LTTng Events");