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 "wrapper/random.h"
  20 #include "lttng-events.h"
  21 #include "lttng-tracer.h"
  22
  23 static LIST_HEAD(sessions);
  24 static LIST_HEAD(lttng_transport_list);
  25 static DEFINE_MUTEX(sessions_mutex);
  26 static struct kmem_cache *event_cache;
  27
  28 static void _lttng_event_destroy(struct lttng_event *event);
  29 static void _lttng_channel_destroy(struct lttng_channel *chan);
  30 static int _lttng_event_unregister(struct lttng_event *event);
  31 static
  32 int _lttng_event_metadata_statedump(struct lttng_session *session,
  33                                   struct lttng_channel *chan,
  34                                   struct lttng_event *event);
  35 static
  36 int _lttng_session_metadata_statedump(struct lttng_session *session);
  37
  38 void synchronize_trace(void)
  39 {
  40         synchronize_sched();
  41 #ifdef CONFIG_PREEMPT_RT
  42         synchronize_rcu();
  43 #endif
  44 }
  45
  46 struct lttng_session *lttng_session_create(void)
  47 {
  48         struct lttng_session *session;
  49
  50         mutex_lock(&sessions_mutex);
  51         session = kzalloc(sizeof(struct lttng_session), GFP_KERNEL);
  52         if (!session)
  53                 return NULL;
  54         INIT_LIST_HEAD(&session->chan);
  55         INIT_LIST_HEAD(&session->events);
  56         uuid_le_gen(&session->uuid);
  57         list_add(&session->list, &sessions);
  58         mutex_unlock(&sessions_mutex);
  59         return session;
  60 }
  61
  62 void lttng_session_destroy(struct lttng_session *session)
  63 {
  64         struct lttng_channel *chan, *tmpchan;
  65         struct lttng_event *event, *tmpevent;
  66         int ret;
  67
  68         mutex_lock(&sessions_mutex);
  69         ACCESS_ONCE(session->active) = 0;
  70         list_for_each_entry(chan, &session->chan, list) {
  71                 ret = lttng_syscalls_unregister(chan);
  72                 WARN_ON(ret);
  73         }
  74         list_for_each_entry(event, &session->events, list) {
  75                 ret = _lttng_event_unregister(event);
  76                 WARN_ON(ret);
  77         }
  78         synchronize_trace();    /* Wait for in-flight events to complete */
  79         list_for_each_entry_safe(event, tmpevent, &session->events, list)
  80                 _lttng_event_destroy(event);
  81         list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
  82                 _lttng_channel_destroy(chan);
  83         list_del(&session->list);
  84         mutex_unlock(&sessions_mutex);
  85         kfree(session);
  86 }
  87
  88 int lttng_session_enable(struct lttng_session *session)
  89 {
  90         int ret = 0;
  91         struct lttng_channel *chan;
  92
  93         mutex_lock(&sessions_mutex);
  94         if (session->active) {
  95                 ret = -EBUSY;
  96                 goto end;
  97         }
  98
  99         /*
 100          * Snapshot the number of events per channel to know the type of header
 101          * we need to use.
 102          */
 103         list_for_each_entry(chan, &session->chan, list) {
 104                 if (chan->header_type)
 105                         continue;               /* don't change it if session stop/restart */
 106                 if (chan->free_event_id < 31)
 107                         chan->header_type = 1;  /* compact */
 108                 else
 109                         chan->header_type = 2;  /* large */
 110         }
 111
 112         ACCESS_ONCE(session->active) = 1;
 113         ACCESS_ONCE(session->been_active) = 1;
 114         ret = _lttng_session_metadata_statedump(session);
 115         if (ret)
 116                 ACCESS_ONCE(session->active) = 0;
 117 end:
 118         mutex_unlock(&sessions_mutex);
 119         return ret;
 120 }
 121
 122 int lttng_session_disable(struct lttng_session *session)
 123 {
 124         int ret = 0;
 125
 126         mutex_lock(&sessions_mutex);
 127         if (!session->active) {
 128                 ret = -EBUSY;
 129                 goto end;
 130         }
 131         ACCESS_ONCE(session->active) = 0;
 132 end:
 133         mutex_unlock(&sessions_mutex);
 134         return ret;
 135 }
 136
 137 int lttng_channel_enable(struct lttng_channel *channel)
 138 {
 139         int old;
 140
 141         if (channel == channel->session->metadata)
 142                 return -EPERM;
 143         old = xchg(&channel->enabled, 1);
 144         if (old)
 145                 return -EEXIST;
 146         return 0;
 147 }
 148
 149 int lttng_channel_disable(struct lttng_channel *channel)
 150 {
 151         int old;
 152
 153         if (channel == channel->session->metadata)
 154                 return -EPERM;
 155         old = xchg(&channel->enabled, 0);
 156         if (!old)
 157                 return -EEXIST;
 158         return 0;
 159 }
 160
 161 int lttng_event_enable(struct lttng_event *event)
 162 {
 163         int old;
 164
 165         if (event->chan == event->chan->session->metadata)
 166                 return -EPERM;
 167         old = xchg(&event->enabled, 1);
 168         if (old)
 169                 return -EEXIST;
 170         return 0;
 171 }
 172
 173 int lttng_event_disable(struct lttng_event *event)
 174 {
 175         int old;
 176
 177         if (event->chan == event->chan->session->metadata)
 178                 return -EPERM;
 179         old = xchg(&event->enabled, 0);
 180         if (!old)
 181                 return -EEXIST;
 182         return 0;
 183 }
 184
 185 static struct lttng_transport *lttng_transport_find(const char *name)
 186 {
 187         struct lttng_transport *transport;
 188
 189         list_for_each_entry(transport, &lttng_transport_list, node) {
 190                 if (!strcmp(transport->name, name))
 191                         return transport;
 192         }
 193         return NULL;
 194 }
 195
 196 struct lttng_channel *lttng_channel_create(struct lttng_session *session,
 197                                        const char *transport_name,
 198                                        void *buf_addr,
 199                                        size_t subbuf_size, size_t num_subbuf,
 200                                        unsigned int switch_timer_interval,
 201                                        unsigned int read_timer_interval)
 202 {
 203         struct lttng_channel *chan;
 204         struct lttng_transport *transport = NULL;
 205
 206         mutex_lock(&sessions_mutex);
 207         if (session->been_active)
 208                 goto active;    /* Refuse to add channel to active session */
 209         transport = lttng_transport_find(transport_name);
 210         if (!transport) {
 211                 printk(KERN_WARNING "LTTng transport %s not found\n",
 212                        transport_name);
 213                 goto notransport;
 214         }
 215         if (!try_module_get(transport->owner)) {
 216                 printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 217                 goto notransport;
 218         }
 219         chan = kzalloc(sizeof(struct lttng_channel), GFP_KERNEL);
 220         if (!chan)
 221                 goto nomem;
 222         chan->session = session;
 223         chan->id = session->free_chan_id++;
 224         /*
 225          * Note: the channel creation op already writes into the packet
 226          * headers. Therefore the "chan" information used as input
 227          * should be already accessible.
 228          */
 229         chan->chan = transport->ops.channel_create("[lttng]", chan, buf_addr,
 230                         subbuf_size, num_subbuf, switch_timer_interval,
 231                         read_timer_interval);
 232         if (!chan->chan)
 233                 goto create_error;
 234         chan->enabled = 1;
 235         chan->ops = &transport->ops;
 236         chan->transport = transport;
 237         list_add(&chan->list, &session->chan);
 238         mutex_unlock(&sessions_mutex);
 239         return chan;
 240
 241 create_error:
 242         kfree(chan);
 243 nomem:
 244         if (transport)
 245                 module_put(transport->owner);
 246 notransport:
 247 active:
 248         mutex_unlock(&sessions_mutex);
 249         return NULL;
 250 }
 251
 252 /*
 253  * Only used internally at session destruction.
 254  */
 255 static
 256 void _lttng_channel_destroy(struct lttng_channel *chan)
 257 {
 258         chan->ops->channel_destroy(chan->chan);
 259         module_put(chan->transport->owner);
 260         list_del(&chan->list);
 261         lttng_destroy_context(chan->ctx);
 262         kfree(chan);
 263 }
 264
 265 /*
 266  * Supports event creation while tracing session is active.
 267  */
 268 struct lttng_event *lttng_event_create(struct lttng_channel *chan,
 269                                    struct lttng_kernel_event *event_param,
 270                                    void *filter,
 271                                    const struct lttng_event_desc *internal_desc)
 272 {
 273         struct lttng_event *event;
 274         int ret;
 275
 276         mutex_lock(&sessions_mutex);
 277         if (chan->free_event_id == -1UL)
 278                 goto full;
 279         /*
 280          * This is O(n^2) (for each event, the loop is called at event
 281          * creation). Might require a hash if we have lots of events.
 282          */
 283         list_for_each_entry(event, &chan->session->events, list)
 284                 if (!strcmp(event->desc->name, event_param->name))
 285                         goto exist;
 286         event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
 287         if (!event)
 288                 goto cache_error;
 289         event->chan = chan;
 290         event->filter = filter;
 291         event->id = chan->free_event_id++;
 292         event->enabled = 1;
 293         event->instrumentation = event_param->instrumentation;
 294         /* Populate lttng_event structure before tracepoint registration. */
 295         smp_wmb();
 296         switch (event_param->instrumentation) {
 297         case LTTNG_KERNEL_TRACEPOINT:
 298                 event->desc = lttng_event_get(event_param->name);
 299                 if (!event->desc)
 300                         goto register_error;
 301                 ret = tracepoint_probe_register(event_param->name,
 302                                 event->desc->probe_callback,
 303                                 event);
 304                 if (ret)
 305                         goto register_error;
 306                 break;
 307         case LTTNG_KERNEL_KPROBE:
 308                 ret = lttng_kprobes_register(event_param->name,
 309                                 event_param->u.kprobe.symbol_name,
 310                                 event_param->u.kprobe.offset,
 311                                 event_param->u.kprobe.addr,
 312                                 event);
 313                 if (ret)
 314                         goto register_error;
 315                 ret = try_module_get(event->desc->owner);
 316                 WARN_ON_ONCE(!ret);
 317                 break;
 318         case LTTNG_KERNEL_KRETPROBE:
 319         {
 320                 struct lttng_event *event_return;
 321
 322                 /* kretprobe defines 2 events */
 323                 event_return =
 324                         kmem_cache_zalloc(event_cache, GFP_KERNEL);
 325                 if (!event_return)
 326                         goto register_error;
 327                 event_return->chan = chan;
 328                 event_return->filter = filter;
 329                 event_return->id = chan->free_event_id++;
 330                 event_return->enabled = 1;
 331                 event_return->instrumentation = event_param->instrumentation;
 332                 /*
 333                  * Populate lttng_event structure before kretprobe registration.
 334                  */
 335                 smp_wmb();
 336                 ret = lttng_kretprobes_register(event_param->name,
 337                                 event_param->u.kretprobe.symbol_name,
 338                                 event_param->u.kretprobe.offset,
 339                                 event_param->u.kretprobe.addr,
 340                                 event, event_return);
 341                 if (ret) {
 342                         kmem_cache_free(event_cache, event_return);
 343                         goto register_error;
 344                 }
 345                 /* Take 2 refs on the module: one per event. */
 346                 ret = try_module_get(event->desc->owner);
 347                 WARN_ON_ONCE(!ret);
 348                 ret = try_module_get(event->desc->owner);
 349                 WARN_ON_ONCE(!ret);
 350                 ret = _lttng_event_metadata_statedump(chan->session, chan,
 351                                                     event_return);
 352                 if (ret) {
 353                         kmem_cache_free(event_cache, event_return);
 354                         module_put(event->desc->owner);
 355                         module_put(event->desc->owner);
 356                         goto statedump_error;
 357                 }
 358                 list_add(&event_return->list, &chan->session->events);
 359                 break;
 360         }
 361         case LTTNG_KERNEL_FUNCTION:
 362                 ret = lttng_ftrace_register(event_param->name,
 363                                 event_param->u.ftrace.symbol_name,
 364                                 event);
 365                 if (ret)
 366                         goto register_error;
 367                 ret = try_module_get(event->desc->owner);
 368                 WARN_ON_ONCE(!ret);
 369                 break;
 370         case LTTNG_KERNEL_NOOP:
 371                 event->desc = internal_desc;
 372                 if (!event->desc)
 373                         goto register_error;
 374                 break;
 375         default:
 376                 WARN_ON_ONCE(1);
 377         }
 378         ret = _lttng_event_metadata_statedump(chan->session, chan, event);
 379         if (ret)
 380                 goto statedump_error;
 381         list_add(&event->list, &chan->session->events);
 382         mutex_unlock(&sessions_mutex);
 383         return event;
 384
 385 statedump_error:
 386         /* If a statedump error occurs, events will not be readable. */
 387 register_error:
 388         kmem_cache_free(event_cache, event);
 389 cache_error:
 390 exist:
 391 full:
 392         mutex_unlock(&sessions_mutex);
 393         return NULL;
 394 }
 395
 396 /*
 397  * Only used internally at session destruction.
 398  */
 399 int _lttng_event_unregister(struct lttng_event *event)
 400 {
 401         int ret = -EINVAL;
 402
 403         switch (event->instrumentation) {
 404         case LTTNG_KERNEL_TRACEPOINT:
 405                 ret = tracepoint_probe_unregister(event->desc->name,
 406                                                   event->desc->probe_callback,
 407                                                   event);
 408                 if (ret)
 409                         return ret;
 410                 break;
 411         case LTTNG_KERNEL_KPROBE:
 412                 lttng_kprobes_unregister(event);
 413                 ret = 0;
 414                 break;
 415         case LTTNG_KERNEL_KRETPROBE:
 416                 lttng_kretprobes_unregister(event);
 417                 ret = 0;
 418                 break;
 419         case LTTNG_KERNEL_FUNCTION:
 420                 lttng_ftrace_unregister(event);
 421                 ret = 0;
 422                 break;
 423         case LTTNG_KERNEL_NOOP:
 424                 ret = 0;
 425                 break;
 426         default:
 427                 WARN_ON_ONCE(1);
 428         }
 429         return ret;
 430 }
 431
 432 /*
 433  * Only used internally at session destruction.
 434  */
 435 static
 436 void _lttng_event_destroy(struct lttng_event *event)
 437 {
 438         switch (event->instrumentation) {
 439         case LTTNG_KERNEL_TRACEPOINT:
 440                 lttng_event_put(event->desc);
 441                 break;
 442         case LTTNG_KERNEL_KPROBE:
 443                 module_put(event->desc->owner);
 444                 lttng_kprobes_destroy_private(event);
 445                 break;
 446         case LTTNG_KERNEL_KRETPROBE:
 447                 module_put(event->desc->owner);
 448                 lttng_kretprobes_destroy_private(event);
 449                 break;
 450         case LTTNG_KERNEL_FUNCTION:
 451                 module_put(event->desc->owner);
 452                 lttng_ftrace_destroy_private(event);
 453                 break;
 454         case LTTNG_KERNEL_NOOP:
 455                 break;
 456         default:
 457                 WARN_ON_ONCE(1);
 458         }
 459         list_del(&event->list);
 460         lttng_destroy_context(event->ctx);
 461         kmem_cache_free(event_cache, event);
 462 }
 463
 464 /*
 465  * We have exclusive access to our metadata buffer (protected by the
 466  * sessions_mutex), so we can do racy operations such as looking for
 467  * remaining space left in packet and write, since mutual exclusion
 468  * protects us from concurrent writes.
 469  */
 470 int lttng_metadata_printf(struct lttng_session *session,
 471                           const char *fmt, ...)
 472 {
 473         struct lib_ring_buffer_ctx ctx;
 474         struct lttng_channel *chan = session->metadata;
 475         char *str;
 476         int ret = 0, waitret;
 477         size_t len, reserve_len, pos;
 478         va_list ap;
 479
 480         WARN_ON_ONCE(!ACCESS_ONCE(session->active));
 481
 482         va_start(ap, fmt);
 483         str = kvasprintf(GFP_KERNEL, fmt, ap);
 484         va_end(ap);
 485         if (!str)
 486                 return -ENOMEM;
 487
 488         len = strlen(str);
 489         pos = 0;
 490
 491         for (pos = 0; pos < len; pos += reserve_len) {
 492                 reserve_len = min_t(size_t,
 493                                 chan->ops->packet_avail_size(chan->chan),
 494                                 len - pos);
 495                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 496                                          sizeof(char), -1);
 497                 /*
 498                  * We don't care about metadata buffer's records lost
 499                  * count, because we always retry here. Report error if
 500                  * we need to bail out after timeout or being
 501                  * interrupted.
 502                  */
 503                 waitret = wait_event_interruptible_timeout(*chan->ops->get_writer_buf_wait_queue(chan->chan, -1),
 504                         ({
 505                                 ret = chan->ops->event_reserve(&ctx, 0);
 506                                 ret != -ENOBUFS || !ret;
 507                         }),
 508                         msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC));
 509                 if (!waitret || waitret == -ERESTARTSYS || ret) {
 510                         printk(KERN_WARNING "LTTng: Failure to write metadata to buffers (%s)\n",
 511                                 waitret == -ERESTARTSYS ? "interrupted" :
 512                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 513                         if (waitret == -ERESTARTSYS)
 514                                 ret = waitret;
 515                         goto end;
 516                 }
 517                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 518                 chan->ops->event_commit(&ctx);
 519         }
 520 end:
 521         kfree(str);
 522         return ret;
 523 }
 524
 525 static
 526 int _lttng_field_statedump(struct lttng_session *session,
 527                          const struct lttng_event_field *field)
 528 {
 529         int ret = 0;
 530
 531         switch (field->type.atype) {
 532         case atype_integer:
 533                 ret = lttng_metadata_printf(session,
 534                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 535                         field->type.u.basic.integer.size,
 536                         field->type.u.basic.integer.alignment,
 537                         field->type.u.basic.integer.signedness,
 538                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 539                                 ? "none"
 540                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 541                                         ? "UTF8"
 542                                         : "ASCII",
 543                         field->type.u.basic.integer.base,
 544 #ifdef __BIG_ENDIAN
 545                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 546 #else
 547                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 548 #endif
 549                         field->name);
 550                 break;
 551         case atype_enum:
 552                 ret = lttng_metadata_printf(session,
 553                         "               %s _%s;\n",
 554                         field->type.u.basic.enumeration.name,
 555                         field->name);
 556                 break;
 557         case atype_array:
 558         {
 559                 const struct lttng_basic_type *elem_type;
 560
 561                 elem_type = &field->type.u.array.elem_type;
 562                 ret = lttng_metadata_printf(session,
 563                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 564                         elem_type->u.basic.integer.size,
 565                         elem_type->u.basic.integer.alignment,
 566                         elem_type->u.basic.integer.signedness,
 567                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 568                                 ? "none"
 569                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 570                                         ? "UTF8"
 571                                         : "ASCII",
 572                         elem_type->u.basic.integer.base,
 573 #ifdef __BIG_ENDIAN
 574                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 575 #else
 576                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 577 #endif
 578                         field->name, field->type.u.array.length);
 579                 break;
 580         }
 581         case atype_sequence:
 582         {
 583                 const struct lttng_basic_type *elem_type;
 584                 const struct lttng_basic_type *length_type;
 585
 586                 elem_type = &field->type.u.sequence.elem_type;
 587                 length_type = &field->type.u.sequence.length_type;
 588                 ret = lttng_metadata_printf(session,
 589                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 590                         length_type->u.basic.integer.size,
 591                         (unsigned int) length_type->u.basic.integer.alignment,
 592                         length_type->u.basic.integer.signedness,
 593                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 594                                 ? "none"
 595                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 596                                         ? "UTF8"
 597                                         : "ASCII"),
 598                         length_type->u.basic.integer.base,
 599 #ifdef __BIG_ENDIAN
 600                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 601 #else
 602                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 603 #endif
 604                         field->name);
 605                 if (ret)
 606                         return ret;
 607
 608                 ret = lttng_metadata_printf(session,
 609                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 610                         elem_type->u.basic.integer.size,
 611                         (unsigned int) elem_type->u.basic.integer.alignment,
 612                         elem_type->u.basic.integer.signedness,
 613                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 614                                 ? "none"
 615                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 616                                         ? "UTF8"
 617                                         : "ASCII"),
 618                         elem_type->u.basic.integer.base,
 619 #ifdef __BIG_ENDIAN
 620                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 621 #else
 622                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 623 #endif
 624                         field->name,
 625                         field->name);
 626                 break;
 627         }
 628
 629         case atype_string:
 630                 /* Default encoding is UTF8 */
 631                 ret = lttng_metadata_printf(session,
 632                         "               string%s _%s;\n",
 633                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 634                                 " { encoding = ASCII; }" : "",
 635                         field->name);
 636                 break;
 637         default:
 638                 WARN_ON_ONCE(1);
 639                 return -EINVAL;
 640         }
 641         return ret;
 642 }
 643
 644 static
 645 int _lttng_context_metadata_statedump(struct lttng_session *session,
 646                                     struct lttng_ctx *ctx)
 647 {
 648         int ret = 0;
 649         int i;
 650
 651         if (!ctx)
 652                 return 0;
 653         for (i = 0; i < ctx->nr_fields; i++) {
 654                 const struct lttng_ctx_field *field = &ctx->fields[i];
 655
 656                 ret = _lttng_field_statedump(session, &field->event_field);
 657                 if (ret)
 658                         return ret;
 659         }
 660         return ret;
 661 }
 662
 663 static
 664 int _lttng_fields_metadata_statedump(struct lttng_session *session,
 665                                    struct lttng_event *event)
 666 {
 667         const struct lttng_event_desc *desc = event->desc;
 668         int ret = 0;
 669         int i;
 670
 671         for (i = 0; i < desc->nr_fields; i++) {
 672                 const struct lttng_event_field *field = &desc->fields[i];
 673
 674                 ret = _lttng_field_statedump(session, field);
 675                 if (ret)
 676                         return ret;
 677         }
 678         return ret;
 679 }
 680
 681 static
 682 int _lttng_event_metadata_statedump(struct lttng_session *session,
 683                                   struct lttng_channel *chan,
 684                                   struct lttng_event *event)
 685 {
 686         int ret = 0;
 687
 688         if (event->metadata_dumped || !ACCESS_ONCE(session->active))
 689                 return 0;
 690         if (chan == session->metadata)
 691                 return 0;
 692
 693         ret = lttng_metadata_printf(session,
 694                 "event {\n"
 695                 "       name = %s;\n"
 696                 "       id = %u;\n"
 697                 "       stream_id = %u;\n",
 698                 event->desc->name,
 699                 event->id,
 700                 event->chan->id);
 701         if (ret)
 702                 goto end;
 703
 704         if (event->ctx) {
 705                 ret = lttng_metadata_printf(session,
 706                         "       context := struct {\n");
 707                 if (ret)
 708                         goto end;
 709         }
 710         ret = _lttng_context_metadata_statedump(session, event->ctx);
 711         if (ret)
 712                 goto end;
 713         if (event->ctx) {
 714                 ret = lttng_metadata_printf(session,
 715                         "       };\n");
 716                 if (ret)
 717                         goto end;
 718         }
 719
 720         ret = lttng_metadata_printf(session,
 721                 "       fields := struct {\n"
 722                 );
 723         if (ret)
 724                 goto end;
 725
 726         ret = _lttng_fields_metadata_statedump(session, event);
 727         if (ret)
 728                 goto end;
 729
 730         /*
 731          * LTTng space reservation can only reserve multiples of the
 732          * byte size.
 733          */
 734         ret = lttng_metadata_printf(session,
 735                 "       };\n"
 736                 "};\n\n");
 737         if (ret)
 738                 goto end;
 739
 740         event->metadata_dumped = 1;
 741 end:
 742         return ret;
 743
 744 }
 745
 746 static
 747 int _lttng_channel_metadata_statedump(struct lttng_session *session,
 748                                     struct lttng_channel *chan)
 749 {
 750         int ret = 0;
 751
 752         if (chan->metadata_dumped || !ACCESS_ONCE(session->active))
 753                 return 0;
 754         if (chan == session->metadata)
 755                 return 0;
 756
 757         WARN_ON_ONCE(!chan->header_type);
 758         ret = lttng_metadata_printf(session,
 759                 "stream {\n"
 760                 "       id = %u;\n"
 761                 "       event.header := %s;\n"
 762                 "       packet.context := struct packet_context;\n",
 763                 chan->id,
 764                 chan->header_type == 1 ? "struct event_header_compact" :
 765                         "struct event_header_large");
 766         if (ret)
 767                 goto end;
 768
 769         if (chan->ctx) {
 770                 ret = lttng_metadata_printf(session,
 771                         "       event.context := struct {\n");
 772                 if (ret)
 773                         goto end;
 774         }
 775         ret = _lttng_context_metadata_statedump(session, chan->ctx);
 776         if (ret)
 777                 goto end;
 778         if (chan->ctx) {
 779                 ret = lttng_metadata_printf(session,
 780                         "       };\n");
 781                 if (ret)
 782                         goto end;
 783         }
 784
 785         ret = lttng_metadata_printf(session,
 786                 "};\n\n");
 787
 788         chan->metadata_dumped = 1;
 789 end:
 790         return ret;
 791 }
 792
 793 static
 794 int _lttng_stream_packet_context_declare(struct lttng_session *session)
 795 {
 796         return lttng_metadata_printf(session,
 797                 "struct packet_context {\n"
 798                 "       uint64_clock_monotonic_t timestamp_begin;\n"
 799                 "       uint64_clock_monotonic_t timestamp_end;\n"
 800                 "       uint32_t events_discarded;\n"
 801                 "       uint32_t content_size;\n"
 802                 "       uint32_t packet_size;\n"
 803                 "       uint32_t cpu_id;\n"
 804                 "};\n\n"
 805                 );
 806 }
 807
 808 /*
 809  * Compact header:
 810  * id: range: 0 - 30.
 811  * id 31 is reserved to indicate an extended header.
 812  *
 813  * Large header:
 814  * id: range: 0 - 65534.
 815  * id 65535 is reserved to indicate an extended header.
 816  */
 817 static
 818 int _lttng_event_header_declare(struct lttng_session *session)
 819 {
 820         return lttng_metadata_printf(session,
 821         "struct event_header_compact {\n"
 822         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
 823         "       variant <id> {\n"
 824         "               struct {\n"
 825         "                       uint27_clock_monotonic_t timestamp;\n"
 826         "               } compact;\n"
 827         "               struct {\n"
 828         "                       uint32_t id;\n"
 829         "                       uint64_clock_monotonic_t timestamp;\n"
 830         "               } extended;\n"
 831         "       } v;\n"
 832         "} align(%u);\n"
 833         "\n"
 834         "struct event_header_large {\n"
 835         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
 836         "       variant <id> {\n"
 837         "               struct {\n"
 838         "                       uint32_clock_monotonic_t timestamp;\n"
 839         "               } compact;\n"
 840         "               struct {\n"
 841         "                       uint32_t id;\n"
 842         "                       uint64_clock_monotonic_t timestamp;\n"
 843         "               } extended;\n"
 844         "       } v;\n"
 845         "} align(%u);\n\n",
 846         lttng_alignof(uint32_t) * CHAR_BIT,
 847         lttng_alignof(uint16_t) * CHAR_BIT
 848         );
 849 }
 850
 851  /*
 852  * Approximation of NTP time of day to clock monotonic correlation,
 853  * taken at start of trace.
 854  * Yes, this is only an approximation. Yes, we can (and will) do better
 855  * in future versions.
 856  */
 857 static
 858 uint64_t measure_clock_offset(void)
 859 {
 860         uint64_t offset, monotonic[2], realtime;
 861         struct timespec rts = { 0, 0 };
 862         unsigned long flags;
 863
 864         /* Disable interrupts to increase correlation precision. */
 865         local_irq_save(flags);
 866         monotonic[0] = trace_clock_read64();
 867         getnstimeofday(&rts);
 868         monotonic[1] = trace_clock_read64();
 869         local_irq_restore(flags);
 870
 871         offset = (monotonic[0] + monotonic[1]) >> 1;
 872         realtime = rts.tv_sec * NSEC_PER_SEC;
 873         realtime += rts.tv_nsec;
 874         offset = realtime - offset;
 875         return offset;
 876 }
 877
 878 /*
 879  * Output metadata into this session's metadata buffers.
 880  */
 881 static
 882 int _lttng_session_metadata_statedump(struct lttng_session *session)
 883 {
 884         unsigned char *uuid_c = session->uuid.b;
 885         unsigned char uuid_s[37], clock_uuid_s[BOOT_ID_LEN];
 886         struct lttng_channel *chan;
 887         struct lttng_event *event;
 888         int ret = 0;
 889
 890         if (!ACCESS_ONCE(session->active))
 891                 return 0;
 892         if (session->metadata_dumped)
 893                 goto skip_session;
 894         if (!session->metadata) {
 895                 printk(KERN_WARNING "LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
 896                 return -EPERM;
 897         }
 898
 899         snprintf(uuid_s, sizeof(uuid_s),
 900                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 901                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
 902                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
 903                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
 904                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
 905
 906         ret = lttng_metadata_printf(session,
 907                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
 908                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
 909                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
 910                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
 911                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
 912                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
 913                 "\n"
 914                 "trace {\n"
 915                 "       major = %u;\n"
 916                 "       minor = %u;\n"
 917                 "       uuid = \"%s\";\n"
 918                 "       byte_order = %s;\n"
 919                 "       packet.header := struct {\n"
 920                 "               uint32_t magic;\n"
 921                 "               uint8_t  uuid[16];\n"
 922                 "               uint32_t stream_id;\n"
 923                 "       };\n"
 924                 "};\n\n",
 925                 lttng_alignof(uint8_t) * CHAR_BIT,
 926                 lttng_alignof(uint16_t) * CHAR_BIT,
 927                 lttng_alignof(uint32_t) * CHAR_BIT,
 928                 lttng_alignof(uint64_t) * CHAR_BIT,
 929                 CTF_VERSION_MAJOR,
 930                 CTF_VERSION_MINOR,
 931                 uuid_s,
 932 #ifdef __BIG_ENDIAN
 933                 "be"
 934 #else
 935                 "le"
 936 #endif
 937                 );
 938         if (ret)
 939                 goto end;
 940
 941         ret = lttng_metadata_printf(session,
 942                 "clock {\n"
 943                 "       name = %s;\n",
 944                 "monotonic"
 945                 );
 946         if (ret)
 947                 goto end;
 948
 949         if (!trace_clock_uuid(clock_uuid_s)) {
 950                 ret = lttng_metadata_printf(session,
 951                         "       uuid = %s;\n",
 952                         clock_uuid_s
 953                         );
 954                 if (ret)
 955                         goto end;
 956         }
 957
 958         ret = lttng_metadata_printf(session,
 959                 "       description = \"Monotonic Clock\";\n"
 960                 "       freq = %llu; /* Frequency, in Hz */\n"
 961                 "       /* clock value offset from Epoch is: offset * (1/freq) */\n"
 962                 "       offset = %llu;\n"
 963                 "};\n\n",
 964                 (unsigned long long) trace_clock_freq(),
 965                 (unsigned long long) measure_clock_offset()
 966                 );
 967         if (ret)
 968                 goto end;
 969
 970         ret = lttng_metadata_printf(session,
 971                 "typealias integer {\n"
 972                 "       size = 27; align = 1; signed = false;\n"
 973                 "       map = clock.monotonic.value;\n"
 974                 "} := uint27_clock_monotonic_t;\n"
 975                 "\n"
 976                 "typealias integer {\n"
 977                 "       size = 32; align = %u; signed = false;\n"
 978                 "       map = clock.monotonic.value;\n"
 979                 "} := uint32_clock_monotonic_t;\n"
 980                 "\n"
 981                 "typealias integer {\n"
 982                 "       size = 64; align = %u; signed = false;\n"
 983                 "       map = clock.monotonic.value;\n"
 984                 "} := uint64_clock_monotonic_t;\n\n",
 985                 lttng_alignof(uint32_t) * CHAR_BIT,
 986                 lttng_alignof(uint64_t) * CHAR_BIT
 987                 );
 988         if (ret)
 989                 goto end;
 990
 991         ret = _lttng_stream_packet_context_declare(session);
 992         if (ret)
 993                 goto end;
 994
 995         ret = _lttng_event_header_declare(session);
 996         if (ret)
 997                 goto end;
 998
 999 skip_session:
1000         list_for_each_entry(chan, &session->chan, list) {
1001                 ret = _lttng_channel_metadata_statedump(session, chan);
1002                 if (ret)
1003                         goto end;
1004         }
1005
1006         list_for_each_entry(event, &session->events, list) {
1007                 ret = _lttng_event_metadata_statedump(session, event->chan, event);
1008                 if (ret)
1009                         goto end;
1010         }
1011         session->metadata_dumped = 1;
1012 end:
1013         return ret;
1014 }
1015
1016 /**
1017  * lttng_transport_register - LTT transport registration
1018  * @transport: transport structure
1019  *
1020  * Registers a transport which can be used as output to extract the data out of
1021  * LTTng. The module calling this registration function must ensure that no
1022  * trap-inducing code will be executed by the transport functions. E.g.
1023  * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
1024  * is made visible to the transport function. This registration acts as a
1025  * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
1026  * after its registration must it synchronize the TLBs.
1027  */
1028 void lttng_transport_register(struct lttng_transport *transport)
1029 {
1030         /*
1031          * Make sure no page fault can be triggered by the module about to be
1032          * registered. We deal with this here so we don't have to call
1033          * vmalloc_sync_all() in each module's init.
1034          */
1035         wrapper_vmalloc_sync_all();
1036
1037         mutex_lock(&sessions_mutex);
1038         list_add_tail(&transport->node, &lttng_transport_list);
1039         mutex_unlock(&sessions_mutex);
1040 }
1041 EXPORT_SYMBOL_GPL(lttng_transport_register);
1042
1043 /**
1044  * lttng_transport_unregister - LTT transport unregistration
1045  * @transport: transport structure
1046  */
1047 void lttng_transport_unregister(struct lttng_transport *transport)
1048 {
1049         mutex_lock(&sessions_mutex);
1050         list_del(&transport->node);
1051         mutex_unlock(&sessions_mutex);
1052 }
1053 EXPORT_SYMBOL_GPL(lttng_transport_unregister);
1054
1055 static int __init lttng_events_init(void)
1056 {
1057         int ret;
1058
1059         event_cache = KMEM_CACHE(lttng_event, 0);
1060         if (!event_cache)
1061                 return -ENOMEM;
1062         ret = lttng_abi_init();
1063         if (ret)
1064                 goto error_abi;
1065         return 0;
1066 error_abi:
1067         kmem_cache_destroy(event_cache);
1068         return ret;
1069 }
1070
1071 module_init(lttng_events_init);
1072
1073 static void __exit lttng_events_exit(void)
1074 {
1075         struct lttng_session *session, *tmpsession;
1076
1077         lttng_abi_exit();
1078         list_for_each_entry_safe(session, tmpsession, &sessions, list)
1079                 lttng_session_destroy(session);
1080         kmem_cache_destroy(event_cache);
1081 }
1082
1083 module_exit(lttng_events_exit);
1084
1085 MODULE_LICENSE("GPL and additional rights");
1086 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1087 MODULE_DESCRIPTION("LTTng Events");