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(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 = _ltt_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                 _ltt_event_destroy(event);
  80         list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
  81                 _ltt_channel_destroy(chan);
  82         list_del(&session->list);
  83         mutex_unlock(&sessions_mutex);
  84         kfree(session);
  85 }
  86
  87 int ltt_session_enable(struct ltt_session *session)
  88 {
  89         int ret = 0;
  90         struct ltt_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 = _ltt_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 ltt_session_disable(struct ltt_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 ltt_channel_enable(struct ltt_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 ltt_channel_disable(struct ltt_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 ltt_event_enable(struct ltt_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 ltt_event_disable(struct ltt_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 ltt_transport *ltt_transport_find(const char *name)
 185 {
 186         struct ltt_transport *transport;
 187
 188         list_for_each_entry(transport, &ltt_transport_list, node) {
 189                 if (!strcmp(transport->name, name))
 190                         return transport;
 191         }
 192         return NULL;
 193 }
 194
 195 struct ltt_channel *ltt_channel_create(struct ltt_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 ltt_channel *chan;
 203         struct ltt_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 = ltt_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 ltt_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 _ltt_channel_destroy(struct ltt_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 ltt_event *ltt_event_create(struct ltt_channel *chan,
 268                                    struct lttng_kernel_event *event_param,
 269                                    void *filter)
 270 {
 271         struct ltt_event *event;
 272         int ret;
 273
 274         mutex_lock(&sessions_mutex);
 275         if (chan->free_event_id == -1UL)
 276                 goto full;
 277         /*
 278          * This is O(n^2) (for each event, the loop is called at event
 279          * creation). Might require a hash if we have lots of events.
 280          */
 281         list_for_each_entry(event, &chan->session->events, list)
 282                 if (!strcmp(event->desc->name, event_param->name))
 283                         goto exist;
 284         event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
 285         if (!event)
 286                 goto cache_error;
 287         event->chan = chan;
 288         event->filter = filter;
 289         event->id = chan->free_event_id++;
 290         event->enabled = 1;
 291         event->instrumentation = event_param->instrumentation;
 292         /* Populate ltt_event structure before tracepoint registration. */
 293         smp_wmb();
 294         switch (event_param->instrumentation) {
 295         case LTTNG_KERNEL_TRACEPOINT:
 296                 event->desc = ltt_event_get(event_param->name);
 297                 if (!event->desc)
 298                         goto register_error;
 299                 ret = tracepoint_probe_register(event_param->name,
 300                                 event->desc->probe_callback,
 301                                 event);
 302                 if (ret)
 303                         goto register_error;
 304                 break;
 305         case LTTNG_KERNEL_KPROBE:
 306                 ret = lttng_kprobes_register(event_param->name,
 307                                 event_param->u.kprobe.symbol_name,
 308                                 event_param->u.kprobe.offset,
 309                                 event_param->u.kprobe.addr,
 310                                 event);
 311                 if (ret)
 312                         goto register_error;
 313                 ret = try_module_get(event->desc->owner);
 314                 WARN_ON_ONCE(!ret);
 315                 break;
 316         case LTTNG_KERNEL_KRETPROBE:
 317         {
 318                 struct ltt_event *event_return;
 319
 320                 /* kretprobe defines 2 events */
 321                 event_return =
 322                         kmem_cache_zalloc(event_cache, GFP_KERNEL);
 323                 if (!event_return)
 324                         goto register_error;
 325                 event_return->chan = chan;
 326                 event_return->filter = filter;
 327                 event_return->id = chan->free_event_id++;
 328                 event_return->enabled = 1;
 329                 event_return->instrumentation = event_param->instrumentation;
 330                 /*
 331                  * Populate ltt_event structure before kretprobe registration.
 332                  */
 333                 smp_wmb();
 334                 ret = lttng_kretprobes_register(event_param->name,
 335                                 event_param->u.kretprobe.symbol_name,
 336                                 event_param->u.kretprobe.offset,
 337                                 event_param->u.kretprobe.addr,
 338                                 event, event_return);
 339                 if (ret) {
 340                         kmem_cache_free(event_cache, event_return);
 341                         goto register_error;
 342                 }
 343                 /* Take 2 refs on the module: one per event. */
 344                 ret = try_module_get(event->desc->owner);
 345                 WARN_ON_ONCE(!ret);
 346                 ret = try_module_get(event->desc->owner);
 347                 WARN_ON_ONCE(!ret);
 348                 ret = _ltt_event_metadata_statedump(chan->session, chan,
 349                                                     event_return);
 350                 if (ret) {
 351                         kmem_cache_free(event_cache, event_return);
 352                         module_put(event->desc->owner);
 353                         module_put(event->desc->owner);
 354                         goto statedump_error;
 355                 }
 356                 list_add(&event_return->list, &chan->session->events);
 357                 break;
 358         }
 359         case LTTNG_KERNEL_FUNCTION:
 360                 ret = lttng_ftrace_register(event_param->name,
 361                                 event_param->u.ftrace.symbol_name,
 362                                 event);
 363                 if (ret)
 364                         goto register_error;
 365                 ret = try_module_get(event->desc->owner);
 366                 WARN_ON_ONCE(!ret);
 367                 break;
 368         case LTTNG_KERNEL_NOOP:
 369                 break;
 370         default:
 371                 WARN_ON_ONCE(1);
 372         }
 373         ret = _ltt_event_metadata_statedump(chan->session, chan, event);
 374         if (ret)
 375                 goto statedump_error;
 376         list_add(&event->list, &chan->session->events);
 377         mutex_unlock(&sessions_mutex);
 378         return event;
 379
 380 statedump_error:
 381         WARN_ON_ONCE(tracepoint_probe_unregister(event_param->name,
 382                                 event->desc->probe_callback,
 383                                 event));
 384         ltt_event_put(event->desc);
 385 register_error:
 386         kmem_cache_free(event_cache, event);
 387 cache_error:
 388 exist:
 389 full:
 390         mutex_unlock(&sessions_mutex);
 391         return NULL;
 392 }
 393
 394 /*
 395  * Only used internally at session destruction.
 396  */
 397 int _ltt_event_unregister(struct ltt_event *event)
 398 {
 399         int ret = -EINVAL;
 400
 401         switch (event->instrumentation) {
 402         case LTTNG_KERNEL_TRACEPOINT:
 403                 ret = tracepoint_probe_unregister(event->desc->name,
 404                                                   event->desc->probe_callback,
 405                                                   event);
 406                 if (ret)
 407                         return ret;
 408                 break;
 409         case LTTNG_KERNEL_KPROBE:
 410                 lttng_kprobes_unregister(event);
 411                 ret = 0;
 412                 break;
 413         case LTTNG_KERNEL_KRETPROBE:
 414                 lttng_kretprobes_unregister(event);
 415                 ret = 0;
 416                 break;
 417         case LTTNG_KERNEL_FUNCTION:
 418                 lttng_ftrace_unregister(event);
 419                 ret = 0;
 420                 break;
 421         default:
 422                 WARN_ON_ONCE(1);
 423         }
 424         return ret;
 425 }
 426
 427 /*
 428  * Only used internally at session destruction.
 429  */
 430 static
 431 void _ltt_event_destroy(struct ltt_event *event)
 432 {
 433         switch (event->instrumentation) {
 434         case LTTNG_KERNEL_TRACEPOINT:
 435                 ltt_event_put(event->desc);
 436                 break;
 437         case LTTNG_KERNEL_KPROBE:
 438                 module_put(event->desc->owner);
 439                 lttng_kprobes_destroy_private(event);
 440                 break;
 441         case LTTNG_KERNEL_KRETPROBE:
 442                 module_put(event->desc->owner);
 443                 lttng_kretprobes_destroy_private(event);
 444                 break;
 445         case LTTNG_KERNEL_FUNCTION:
 446                 module_put(event->desc->owner);
 447                 lttng_ftrace_destroy_private(event);
 448                 break;
 449         default:
 450                 WARN_ON_ONCE(1);
 451         }
 452         list_del(&event->list);
 453         lttng_destroy_context(event->ctx);
 454         kmem_cache_free(event_cache, event);
 455 }
 456
 457 /*
 458  * We have exclusive access to our metadata buffer (protected by the
 459  * sessions_mutex), so we can do racy operations such as looking for
 460  * remaining space left in packet and write, since mutual exclusion
 461  * protects us from concurrent writes.
 462  */
 463 int lttng_metadata_printf(struct ltt_session *session,
 464                           const char *fmt, ...)
 465 {
 466         struct lib_ring_buffer_ctx ctx;
 467         struct ltt_channel *chan = session->metadata;
 468         char *str;
 469         int ret = 0, waitret;
 470         size_t len, reserve_len, pos;
 471         va_list ap;
 472
 473         WARN_ON_ONCE(!ACCESS_ONCE(session->active));
 474
 475         va_start(ap, fmt);
 476         str = kvasprintf(GFP_KERNEL, fmt, ap);
 477         va_end(ap);
 478         if (!str)
 479                 return -ENOMEM;
 480
 481         len = strlen(str);
 482         pos = 0;
 483
 484         for (pos = 0; pos < len; pos += reserve_len) {
 485                 reserve_len = min_t(size_t,
 486                                 chan->ops->packet_avail_size(chan->chan),
 487                                 len - pos);
 488                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 489                                          sizeof(char), -1);
 490                 /*
 491                  * We don't care about metadata buffer's records lost
 492                  * count, because we always retry here. Report error if
 493                  * we need to bail out after timeout or being
 494                  * interrupted.
 495                  */
 496                 waitret = wait_event_interruptible_timeout(*chan->ops->get_writer_buf_wait_queue(chan->chan, -1),
 497                         ({
 498                                 ret = chan->ops->event_reserve(&ctx, 0);
 499                                 ret != -ENOBUFS || !ret;
 500                         }),
 501                         msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC));
 502                 if (!waitret || waitret == -ERESTARTSYS || ret) {
 503                         printk(KERN_WARNING "LTTng: Failure to write metadata to buffers (%s)\n",
 504                                 waitret == -ERESTARTSYS ? "interrupted" :
 505                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 506                         if (waitret == -ERESTARTSYS)
 507                                 ret = waitret;
 508                         goto end;
 509                 }
 510                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 511                 chan->ops->event_commit(&ctx);
 512         }
 513 end:
 514         kfree(str);
 515         return ret;
 516 }
 517
 518 static
 519 int _ltt_field_statedump(struct ltt_session *session,
 520                          const struct lttng_event_field *field)
 521 {
 522         int ret = 0;
 523
 524         switch (field->type.atype) {
 525         case atype_integer:
 526                 ret = lttng_metadata_printf(session,
 527                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s;\n",
 528                         field->type.u.basic.integer.size,
 529                         field->type.u.basic.integer.alignment,
 530                         field->type.u.basic.integer.signedness,
 531                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 532                                 ? "none"
 533                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 534                                         ? "UTF8"
 535                                         : "ASCII",
 536                         field->type.u.basic.integer.base,
 537 #ifdef __BIG_ENDIAN
 538                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 539 #else
 540                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 541 #endif
 542                         field->name);
 543                 break;
 544         case atype_enum:
 545                 ret = lttng_metadata_printf(session,
 546                         "               %s %s;\n",
 547                         field->type.u.basic.enumeration.name,
 548                         field->name);
 549                 break;
 550         case atype_array:
 551         {
 552                 const struct lttng_basic_type *elem_type;
 553
 554                 elem_type = &field->type.u.array.elem_type;
 555                 ret = lttng_metadata_printf(session,
 556                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[%u];\n",
 557                         elem_type->u.basic.integer.size,
 558                         elem_type->u.basic.integer.alignment,
 559                         elem_type->u.basic.integer.signedness,
 560                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 561                                 ? "none"
 562                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 563                                         ? "UTF8"
 564                                         : "ASCII",
 565                         elem_type->u.basic.integer.base,
 566 #ifdef __BIG_ENDIAN
 567                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 568 #else
 569                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 570 #endif
 571                         field->name, field->type.u.array.length);
 572                 break;
 573         }
 574         case atype_sequence:
 575         {
 576                 const struct lttng_basic_type *elem_type;
 577                 const struct lttng_basic_type *length_type;
 578
 579                 elem_type = &field->type.u.sequence.elem_type;
 580                 length_type = &field->type.u.sequence.length_type;
 581                 ret = lttng_metadata_printf(session,
 582                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 583                         length_type->u.basic.integer.size,
 584                         (unsigned int) length_type->u.basic.integer.alignment,
 585                         length_type->u.basic.integer.signedness,
 586                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 587                                 ? "none"
 588                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 589                                         ? "UTF8"
 590                                         : "ASCII"),
 591                         length_type->u.basic.integer.base,
 592 #ifdef __BIG_ENDIAN
 593                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 594 #else
 595                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 596 #endif
 597                         field->name);
 598                 if (ret)
 599                         return ret;
 600
 601                 ret = lttng_metadata_printf(session,
 602                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[ __%s_length ];\n",
 603                         elem_type->u.basic.integer.size,
 604                         (unsigned int) elem_type->u.basic.integer.alignment,
 605                         elem_type->u.basic.integer.signedness,
 606                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 607                                 ? "none"
 608                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 609                                         ? "UTF8"
 610                                         : "ASCII"),
 611                         elem_type->u.basic.integer.base,
 612 #ifdef __BIG_ENDIAN
 613                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 614 #else
 615                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 616 #endif
 617                         field->name,
 618                         field->name);
 619                 break;
 620         }
 621
 622         case atype_string:
 623                 /* Default encoding is UTF8 */
 624                 ret = lttng_metadata_printf(session,
 625                         "               string%s %s;\n",
 626                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 627                                 " { encoding = ASCII; }" : "",
 628                         field->name);
 629                 break;
 630         default:
 631                 WARN_ON_ONCE(1);
 632                 return -EINVAL;
 633         }
 634         return ret;
 635 }
 636
 637 static
 638 int _ltt_context_metadata_statedump(struct ltt_session *session,
 639                                     struct lttng_ctx *ctx)
 640 {
 641         int ret = 0;
 642         int i;
 643
 644         if (!ctx)
 645                 return 0;
 646         for (i = 0; i < ctx->nr_fields; i++) {
 647                 const struct lttng_ctx_field *field = &ctx->fields[i];
 648
 649                 ret = _ltt_field_statedump(session, &field->event_field);
 650                 if (ret)
 651                         return ret;
 652         }
 653         return ret;
 654 }
 655
 656 static
 657 int _ltt_fields_metadata_statedump(struct ltt_session *session,
 658                                    struct ltt_event *event)
 659 {
 660         const struct lttng_event_desc *desc = event->desc;
 661         int ret = 0;
 662         int i;
 663
 664         for (i = 0; i < desc->nr_fields; i++) {
 665                 const struct lttng_event_field *field = &desc->fields[i];
 666
 667                 ret = _ltt_field_statedump(session, field);
 668                 if (ret)
 669                         return ret;
 670         }
 671         return ret;
 672 }
 673
 674 static
 675 int _ltt_event_metadata_statedump(struct ltt_session *session,
 676                                   struct ltt_channel *chan,
 677                                   struct ltt_event *event)
 678 {
 679         int ret = 0;
 680
 681         if (event->metadata_dumped || !ACCESS_ONCE(session->active))
 682                 return 0;
 683         if (chan == session->metadata)
 684                 return 0;
 685
 686         ret = lttng_metadata_printf(session,
 687                 "event {\n"
 688                 "       name = %s;\n"
 689                 "       id = %u;\n"
 690                 "       stream_id = %u;\n",
 691                 event->desc->name,
 692                 event->id,
 693                 event->chan->id);
 694         if (ret)
 695                 goto end;
 696
 697         if (event->ctx) {
 698                 ret = lttng_metadata_printf(session,
 699                         "       context := struct {\n");
 700                 if (ret)
 701                         goto end;
 702         }
 703         ret = _ltt_context_metadata_statedump(session, event->ctx);
 704         if (ret)
 705                 goto end;
 706         if (event->ctx) {
 707                 ret = lttng_metadata_printf(session,
 708                         "       };\n");
 709                 if (ret)
 710                         goto end;
 711         }
 712
 713         ret = lttng_metadata_printf(session,
 714                 "       fields := struct {\n"
 715                 );
 716         if (ret)
 717                 goto end;
 718
 719         ret = _ltt_fields_metadata_statedump(session, event);
 720         if (ret)
 721                 goto end;
 722
 723         /*
 724          * LTTng space reservation can only reserve multiples of the
 725          * byte size.
 726          */
 727         ret = lttng_metadata_printf(session,
 728                 "       };\n"
 729                 "};\n\n");
 730         if (ret)
 731                 goto end;
 732
 733         event->metadata_dumped = 1;
 734 end:
 735         return ret;
 736
 737 }
 738
 739 static
 740 int _ltt_channel_metadata_statedump(struct ltt_session *session,
 741                                     struct ltt_channel *chan)
 742 {
 743         int ret = 0;
 744
 745         if (chan->metadata_dumped || !ACCESS_ONCE(session->active))
 746                 return 0;
 747         if (chan == session->metadata)
 748                 return 0;
 749
 750         WARN_ON_ONCE(!chan->header_type);
 751         ret = lttng_metadata_printf(session,
 752                 "stream {\n"
 753                 "       id = %u;\n"
 754                 "       event.header := %s;\n"
 755                 "       packet.context := struct packet_context;\n",
 756                 chan->id,
 757                 chan->header_type == 1 ? "struct event_header_compact" :
 758                         "struct event_header_large");
 759         if (ret)
 760                 goto end;
 761
 762         if (chan->ctx) {
 763                 ret = lttng_metadata_printf(session,
 764                         "       event.context := struct {\n");
 765                 if (ret)
 766                         goto end;
 767         }
 768         ret = _ltt_context_metadata_statedump(session, chan->ctx);
 769         if (ret)
 770                 goto end;
 771         if (chan->ctx) {
 772                 ret = lttng_metadata_printf(session,
 773                         "       };\n");
 774                 if (ret)
 775                         goto end;
 776         }
 777
 778         ret = lttng_metadata_printf(session,
 779                 "};\n\n");
 780
 781         chan->metadata_dumped = 1;
 782 end:
 783         return ret;
 784 }
 785
 786 static
 787 int _ltt_stream_packet_context_declare(struct ltt_session *session)
 788 {
 789         return lttng_metadata_printf(session,
 790                 "struct packet_context {\n"
 791                 "       uint64_t timestamp_begin;\n"
 792                 "       uint64_t timestamp_end;\n"
 793                 "       uint32_t events_discarded;\n"
 794                 "       uint32_t content_size;\n"
 795                 "       uint32_t packet_size;\n"
 796                 "       uint32_t cpu_id;\n"
 797                 "};\n\n"
 798                 );
 799 }
 800
 801 /*
 802  * Compact header:
 803  * id: range: 0 - 30.
 804  * id 31 is reserved to indicate an extended header.
 805  *
 806  * Large header:
 807  * id: range: 0 - 65534.
 808  * id 65535 is reserved to indicate an extended header.
 809  */
 810 static
 811 int _ltt_event_header_declare(struct ltt_session *session)
 812 {
 813         return lttng_metadata_printf(session,
 814         "struct event_header_compact {\n"
 815         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
 816         "       variant <id> {\n"
 817         "               struct {\n"
 818         "                       uint27_t timestamp;\n"
 819         "               } compact;\n"
 820         "               struct {\n"
 821         "                       uint32_t id;\n"
 822         "                       uint64_t timestamp;\n"
 823         "               } extended;\n"
 824         "       } v;\n"
 825         "} align(%u);\n"
 826         "\n"
 827         "struct event_header_large {\n"
 828         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
 829         "       variant <id> {\n"
 830         "               struct {\n"
 831         "                       uint32_t timestamp;\n"
 832         "               } compact;\n"
 833         "               struct {\n"
 834         "                       uint32_t id;\n"
 835         "                       uint64_t timestamp;\n"
 836         "               } extended;\n"
 837         "       } v;\n"
 838         "} align(%u);\n\n",
 839         ltt_alignof(uint32_t) * CHAR_BIT,
 840         ltt_alignof(uint16_t) * CHAR_BIT
 841         );
 842 }
 843
 844 /*
 845  * Output metadata into this session's metadata buffers.
 846  */
 847 static
 848 int _ltt_session_metadata_statedump(struct ltt_session *session)
 849 {
 850         unsigned char *uuid_c = session->uuid.b;
 851         unsigned char uuid_s[37];
 852         struct ltt_channel *chan;
 853         struct ltt_event *event;
 854         int ret = 0;
 855
 856         if (!ACCESS_ONCE(session->active))
 857                 return 0;
 858         if (session->metadata_dumped)
 859                 goto skip_session;
 860         if (!session->metadata) {
 861                 printk(KERN_WARNING "LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
 862                 return -EPERM;
 863         }
 864
 865         snprintf(uuid_s, sizeof(uuid_s),
 866                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 867                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
 868                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
 869                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
 870                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
 871
 872         ret = lttng_metadata_printf(session,
 873                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
 874                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
 875                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
 876                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
 877                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
 878                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
 879                 "\n"
 880                 "trace {\n"
 881                 "       major = %u;\n"
 882                 "       minor = %u;\n"
 883                 "       uuid = \"%s\";\n"
 884                 "       byte_order = %s;\n"
 885                 "       packet.header := struct {\n"
 886                 "               uint32_t magic;\n"
 887                 "               uint8_t  uuid[16];\n"
 888                 "               uint32_t stream_id;\n"
 889                 "       };\n"
 890                 "};\n\n",
 891                 ltt_alignof(uint8_t) * CHAR_BIT,
 892                 ltt_alignof(uint16_t) * CHAR_BIT,
 893                 ltt_alignof(uint32_t) * CHAR_BIT,
 894                 ltt_alignof(uint64_t) * CHAR_BIT,
 895                 CTF_VERSION_MAJOR,
 896                 CTF_VERSION_MINOR,
 897                 uuid_s,
 898 #ifdef __BIG_ENDIAN
 899                 "be"
 900 #else
 901                 "le"
 902 #endif
 903                 );
 904         if (ret)
 905                 goto end;
 906
 907         ret = _ltt_stream_packet_context_declare(session);
 908         if (ret)
 909                 goto end;
 910
 911         ret = _ltt_event_header_declare(session);
 912         if (ret)
 913                 goto end;
 914
 915 skip_session:
 916         list_for_each_entry(chan, &session->chan, list) {
 917                 ret = _ltt_channel_metadata_statedump(session, chan);
 918                 if (ret)
 919                         goto end;
 920         }
 921
 922         list_for_each_entry(event, &session->events, list) {
 923                 ret = _ltt_event_metadata_statedump(session, event->chan, event);
 924                 if (ret)
 925                         goto end;
 926         }
 927         session->metadata_dumped = 1;
 928 end:
 929         return ret;
 930 }
 931
 932 /**
 933  * ltt_transport_register - LTT transport registration
 934  * @transport: transport structure
 935  *
 936  * Registers a transport which can be used as output to extract the data out of
 937  * LTTng. The module calling this registration function must ensure that no
 938  * trap-inducing code will be executed by the transport functions. E.g.
 939  * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
 940  * is made visible to the transport function. This registration acts as a
 941  * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
 942  * after its registration must it synchronize the TLBs.
 943  */
 944 void ltt_transport_register(struct ltt_transport *transport)
 945 {
 946         /*
 947          * Make sure no page fault can be triggered by the module about to be
 948          * registered. We deal with this here so we don't have to call
 949          * vmalloc_sync_all() in each module's init.
 950          */
 951         wrapper_vmalloc_sync_all();
 952
 953         mutex_lock(&sessions_mutex);
 954         list_add_tail(&transport->node, &ltt_transport_list);
 955         mutex_unlock(&sessions_mutex);
 956 }
 957 EXPORT_SYMBOL_GPL(ltt_transport_register);
 958
 959 /**
 960  * ltt_transport_unregister - LTT transport unregistration
 961  * @transport: transport structure
 962  */
 963 void ltt_transport_unregister(struct ltt_transport *transport)
 964 {
 965         mutex_lock(&sessions_mutex);
 966         list_del(&transport->node);
 967         mutex_unlock(&sessions_mutex);
 968 }
 969 EXPORT_SYMBOL_GPL(ltt_transport_unregister);
 970
 971 static int __init ltt_events_init(void)
 972 {
 973         int ret;
 974
 975         event_cache = KMEM_CACHE(ltt_event, 0);
 976         if (!event_cache)
 977                 return -ENOMEM;
 978         ret = ltt_debugfs_abi_init();
 979         if (ret)
 980                 goto error_abi;
 981         return 0;
 982 error_abi:
 983         kmem_cache_destroy(event_cache);
 984         return ret;
 985 }
 986
 987 module_init(ltt_events_init);
 988
 989 static void __exit ltt_events_exit(void)
 990 {
 991         struct ltt_session *session, *tmpsession;
 992
 993         ltt_debugfs_abi_exit();
 994         list_for_each_entry_safe(session, tmpsession, &sessions, list)
 995                 ltt_session_destroy(session);
 996         kmem_cache_destroy(event_cache);
 997 }
 998
 999 module_exit(ltt_events_exit);
1000
1001 MODULE_LICENSE("GPL and additional rights");
1002 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1003 MODULE_DESCRIPTION("LTTng Events");