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 <linux/utsname.h>
  18 #include "wrapper/uuid.h"
  19 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  20 #include "wrapper/random.h"
  21 #include "lttng-events.h"
  22 #include "lttng-tracer.h"
  23
  24 static LIST_HEAD(sessions);
  25 static LIST_HEAD(lttng_transport_list);
  26 static DEFINE_MUTEX(sessions_mutex);
  27 static struct kmem_cache *event_cache;
  28
  29 static void _lttng_event_destroy(struct lttng_event *event);
  30 static void _lttng_channel_destroy(struct lttng_channel *chan);
  31 static int _lttng_event_unregister(struct lttng_event *event);
  32 static
  33 int _lttng_event_metadata_statedump(struct lttng_session *session,
  34                                   struct lttng_channel *chan,
  35                                   struct lttng_event *event);
  36 static
  37 int _lttng_session_metadata_statedump(struct lttng_session *session);
  38
  39 void synchronize_trace(void)
  40 {
  41         synchronize_sched();
  42 #ifdef CONFIG_PREEMPT_RT
  43         synchronize_rcu();
  44 #endif
  45 }
  46
  47 struct lttng_session *lttng_session_create(void)
  48 {
  49         struct lttng_session *session;
  50
  51         mutex_lock(&sessions_mutex);
  52         session = kzalloc(sizeof(struct lttng_session), GFP_KERNEL);
  53         if (!session)
  54                 return NULL;
  55         INIT_LIST_HEAD(&session->chan);
  56         INIT_LIST_HEAD(&session->events);
  57         uuid_le_gen(&session->uuid);
  58         list_add(&session->list, &sessions);
  59         mutex_unlock(&sessions_mutex);
  60         return session;
  61 }
  62
  63 void lttng_session_destroy(struct lttng_session *session)
  64 {
  65         struct lttng_channel *chan, *tmpchan;
  66         struct lttng_event *event, *tmpevent;
  67         int ret;
  68
  69         mutex_lock(&sessions_mutex);
  70         ACCESS_ONCE(session->active) = 0;
  71         list_for_each_entry(chan, &session->chan, list) {
  72                 ret = lttng_syscalls_unregister(chan);
  73                 WARN_ON(ret);
  74         }
  75         list_for_each_entry(event, &session->events, list) {
  76                 ret = _lttng_event_unregister(event);
  77                 WARN_ON(ret);
  78         }
  79         synchronize_trace();    /* Wait for in-flight events to complete */
  80         list_for_each_entry_safe(event, tmpevent, &session->events, list)
  81                 _lttng_event_destroy(event);
  82         list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
  83                 _lttng_channel_destroy(chan);
  84         list_del(&session->list);
  85         mutex_unlock(&sessions_mutex);
  86         kfree(session);
  87 }
  88
  89 int lttng_session_enable(struct lttng_session *session)
  90 {
  91         int ret = 0;
  92         struct lttng_channel *chan;
  93
  94         mutex_lock(&sessions_mutex);
  95         if (session->active) {
  96                 ret = -EBUSY;
  97                 goto end;
  98         }
  99
 100         /*
 101          * Snapshot the number of events per channel to know the type of header
 102          * we need to use.
 103          */
 104         list_for_each_entry(chan, &session->chan, list) {
 105                 if (chan->header_type)
 106                         continue;               /* don't change it if session stop/restart */
 107                 if (chan->free_event_id < 31)
 108                         chan->header_type = 1;  /* compact */
 109                 else
 110                         chan->header_type = 2;  /* large */
 111         }
 112
 113         ACCESS_ONCE(session->active) = 1;
 114         ACCESS_ONCE(session->been_active) = 1;
 115         ret = _lttng_session_metadata_statedump(session);
 116         if (ret) {
 117                 ACCESS_ONCE(session->active) = 0;
 118                 goto end;
 119         }
 120         ret = lttng_statedump_start(session);
 121         if (ret)
 122                 ACCESS_ONCE(session->active) = 0;
 123 end:
 124         mutex_unlock(&sessions_mutex);
 125         return ret;
 126 }
 127
 128 int lttng_session_disable(struct lttng_session *session)
 129 {
 130         int ret = 0;
 131
 132         mutex_lock(&sessions_mutex);
 133         if (!session->active) {
 134                 ret = -EBUSY;
 135                 goto end;
 136         }
 137         ACCESS_ONCE(session->active) = 0;
 138 end:
 139         mutex_unlock(&sessions_mutex);
 140         return ret;
 141 }
 142
 143 int lttng_channel_enable(struct lttng_channel *channel)
 144 {
 145         int old;
 146
 147         if (channel == channel->session->metadata)
 148                 return -EPERM;
 149         old = xchg(&channel->enabled, 1);
 150         if (old)
 151                 return -EEXIST;
 152         return 0;
 153 }
 154
 155 int lttng_channel_disable(struct lttng_channel *channel)
 156 {
 157         int old;
 158
 159         if (channel == channel->session->metadata)
 160                 return -EPERM;
 161         old = xchg(&channel->enabled, 0);
 162         if (!old)
 163                 return -EEXIST;
 164         return 0;
 165 }
 166
 167 int lttng_event_enable(struct lttng_event *event)
 168 {
 169         int old;
 170
 171         if (event->chan == event->chan->session->metadata)
 172                 return -EPERM;
 173         old = xchg(&event->enabled, 1);
 174         if (old)
 175                 return -EEXIST;
 176         return 0;
 177 }
 178
 179 int lttng_event_disable(struct lttng_event *event)
 180 {
 181         int old;
 182
 183         if (event->chan == event->chan->session->metadata)
 184                 return -EPERM;
 185         old = xchg(&event->enabled, 0);
 186         if (!old)
 187                 return -EEXIST;
 188         return 0;
 189 }
 190
 191 static struct lttng_transport *lttng_transport_find(const char *name)
 192 {
 193         struct lttng_transport *transport;
 194
 195         list_for_each_entry(transport, &lttng_transport_list, node) {
 196                 if (!strcmp(transport->name, name))
 197                         return transport;
 198         }
 199         return NULL;
 200 }
 201
 202 struct lttng_channel *lttng_channel_create(struct lttng_session *session,
 203                                        const char *transport_name,
 204                                        void *buf_addr,
 205                                        size_t subbuf_size, size_t num_subbuf,
 206                                        unsigned int switch_timer_interval,
 207                                        unsigned int read_timer_interval)
 208 {
 209         struct lttng_channel *chan;
 210         struct lttng_transport *transport = NULL;
 211
 212         mutex_lock(&sessions_mutex);
 213         if (session->been_active)
 214                 goto active;    /* Refuse to add channel to active session */
 215         transport = lttng_transport_find(transport_name);
 216         if (!transport) {
 217                 printk(KERN_WARNING "LTTng transport %s not found\n",
 218                        transport_name);
 219                 goto notransport;
 220         }
 221         if (!try_module_get(transport->owner)) {
 222                 printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 223                 goto notransport;
 224         }
 225         chan = kzalloc(sizeof(struct lttng_channel), GFP_KERNEL);
 226         if (!chan)
 227                 goto nomem;
 228         chan->session = session;
 229         chan->id = session->free_chan_id++;
 230         /*
 231          * Note: the channel creation op already writes into the packet
 232          * headers. Therefore the "chan" information used as input
 233          * should be already accessible.
 234          */
 235         chan->chan = transport->ops.channel_create("[lttng]", chan, buf_addr,
 236                         subbuf_size, num_subbuf, switch_timer_interval,
 237                         read_timer_interval);
 238         if (!chan->chan)
 239                 goto create_error;
 240         chan->enabled = 1;
 241         chan->ops = &transport->ops;
 242         chan->transport = transport;
 243         list_add(&chan->list, &session->chan);
 244         mutex_unlock(&sessions_mutex);
 245         return chan;
 246
 247 create_error:
 248         kfree(chan);
 249 nomem:
 250         if (transport)
 251                 module_put(transport->owner);
 252 notransport:
 253 active:
 254         mutex_unlock(&sessions_mutex);
 255         return NULL;
 256 }
 257
 258 /*
 259  * Only used internally at session destruction.
 260  */
 261 static
 262 void _lttng_channel_destroy(struct lttng_channel *chan)
 263 {
 264         chan->ops->channel_destroy(chan->chan);
 265         module_put(chan->transport->owner);
 266         list_del(&chan->list);
 267         lttng_destroy_context(chan->ctx);
 268         kfree(chan);
 269 }
 270
 271 /*
 272  * Supports event creation while tracing session is active.
 273  */
 274 struct lttng_event *lttng_event_create(struct lttng_channel *chan,
 275                                    struct lttng_kernel_event *event_param,
 276                                    void *filter,
 277                                    const struct lttng_event_desc *internal_desc)
 278 {
 279         struct lttng_event *event;
 280         int ret;
 281
 282         mutex_lock(&sessions_mutex);
 283         if (chan->free_event_id == -1UL)
 284                 goto full;
 285         /*
 286          * This is O(n^2) (for each event, the loop is called at event
 287          * creation). Might require a hash if we have lots of events.
 288          */
 289         list_for_each_entry(event, &chan->session->events, list)
 290                 if (!strcmp(event->desc->name, event_param->name))
 291                         goto exist;
 292         event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
 293         if (!event)
 294                 goto cache_error;
 295         event->chan = chan;
 296         event->filter = filter;
 297         event->id = chan->free_event_id++;
 298         event->enabled = 1;
 299         event->instrumentation = event_param->instrumentation;
 300         /* Populate lttng_event structure before tracepoint registration. */
 301         smp_wmb();
 302         switch (event_param->instrumentation) {
 303         case LTTNG_KERNEL_TRACEPOINT:
 304                 event->desc = lttng_event_get(event_param->name);
 305                 if (!event->desc)
 306                         goto register_error;
 307                 ret = tracepoint_probe_register(event_param->name,
 308                                 event->desc->probe_callback,
 309                                 event);
 310                 if (ret)
 311                         goto register_error;
 312                 break;
 313         case LTTNG_KERNEL_KPROBE:
 314                 ret = lttng_kprobes_register(event_param->name,
 315                                 event_param->u.kprobe.symbol_name,
 316                                 event_param->u.kprobe.offset,
 317                                 event_param->u.kprobe.addr,
 318                                 event);
 319                 if (ret)
 320                         goto register_error;
 321                 ret = try_module_get(event->desc->owner);
 322                 WARN_ON_ONCE(!ret);
 323                 break;
 324         case LTTNG_KERNEL_KRETPROBE:
 325         {
 326                 struct lttng_event *event_return;
 327
 328                 /* kretprobe defines 2 events */
 329                 event_return =
 330                         kmem_cache_zalloc(event_cache, GFP_KERNEL);
 331                 if (!event_return)
 332                         goto register_error;
 333                 event_return->chan = chan;
 334                 event_return->filter = filter;
 335                 event_return->id = chan->free_event_id++;
 336                 event_return->enabled = 1;
 337                 event_return->instrumentation = event_param->instrumentation;
 338                 /*
 339                  * Populate lttng_event structure before kretprobe registration.
 340                  */
 341                 smp_wmb();
 342                 ret = lttng_kretprobes_register(event_param->name,
 343                                 event_param->u.kretprobe.symbol_name,
 344                                 event_param->u.kretprobe.offset,
 345                                 event_param->u.kretprobe.addr,
 346                                 event, event_return);
 347                 if (ret) {
 348                         kmem_cache_free(event_cache, event_return);
 349                         goto register_error;
 350                 }
 351                 /* Take 2 refs on the module: one per event. */
 352                 ret = try_module_get(event->desc->owner);
 353                 WARN_ON_ONCE(!ret);
 354                 ret = try_module_get(event->desc->owner);
 355                 WARN_ON_ONCE(!ret);
 356                 ret = _lttng_event_metadata_statedump(chan->session, chan,
 357                                                     event_return);
 358                 if (ret) {
 359                         kmem_cache_free(event_cache, event_return);
 360                         module_put(event->desc->owner);
 361                         module_put(event->desc->owner);
 362                         goto statedump_error;
 363                 }
 364                 list_add(&event_return->list, &chan->session->events);
 365                 break;
 366         }
 367         case LTTNG_KERNEL_FUNCTION:
 368                 ret = lttng_ftrace_register(event_param->name,
 369                                 event_param->u.ftrace.symbol_name,
 370                                 event);
 371                 if (ret)
 372                         goto register_error;
 373                 ret = try_module_get(event->desc->owner);
 374                 WARN_ON_ONCE(!ret);
 375                 break;
 376         case LTTNG_KERNEL_NOOP:
 377                 event->desc = internal_desc;
 378                 if (!event->desc)
 379                         goto register_error;
 380                 break;
 381         default:
 382                 WARN_ON_ONCE(1);
 383         }
 384         ret = _lttng_event_metadata_statedump(chan->session, chan, event);
 385         if (ret)
 386                 goto statedump_error;
 387         list_add(&event->list, &chan->session->events);
 388         mutex_unlock(&sessions_mutex);
 389         return event;
 390
 391 statedump_error:
 392         /* If a statedump error occurs, events will not be readable. */
 393 register_error:
 394         kmem_cache_free(event_cache, event);
 395 cache_error:
 396 exist:
 397 full:
 398         mutex_unlock(&sessions_mutex);
 399         return NULL;
 400 }
 401
 402 /*
 403  * Only used internally at session destruction.
 404  */
 405 int _lttng_event_unregister(struct lttng_event *event)
 406 {
 407         int ret = -EINVAL;
 408
 409         switch (event->instrumentation) {
 410         case LTTNG_KERNEL_TRACEPOINT:
 411                 ret = tracepoint_probe_unregister(event->desc->name,
 412                                                   event->desc->probe_callback,
 413                                                   event);
 414                 if (ret)
 415                         return ret;
 416                 break;
 417         case LTTNG_KERNEL_KPROBE:
 418                 lttng_kprobes_unregister(event);
 419                 ret = 0;
 420                 break;
 421         case LTTNG_KERNEL_KRETPROBE:
 422                 lttng_kretprobes_unregister(event);
 423                 ret = 0;
 424                 break;
 425         case LTTNG_KERNEL_FUNCTION:
 426                 lttng_ftrace_unregister(event);
 427                 ret = 0;
 428                 break;
 429         case LTTNG_KERNEL_NOOP:
 430                 ret = 0;
 431                 break;
 432         default:
 433                 WARN_ON_ONCE(1);
 434         }
 435         return ret;
 436 }
 437
 438 /*
 439  * Only used internally at session destruction.
 440  */
 441 static
 442 void _lttng_event_destroy(struct lttng_event *event)
 443 {
 444         switch (event->instrumentation) {
 445         case LTTNG_KERNEL_TRACEPOINT:
 446                 lttng_event_put(event->desc);
 447                 break;
 448         case LTTNG_KERNEL_KPROBE:
 449                 module_put(event->desc->owner);
 450                 lttng_kprobes_destroy_private(event);
 451                 break;
 452         case LTTNG_KERNEL_KRETPROBE:
 453                 module_put(event->desc->owner);
 454                 lttng_kretprobes_destroy_private(event);
 455                 break;
 456         case LTTNG_KERNEL_FUNCTION:
 457                 module_put(event->desc->owner);
 458                 lttng_ftrace_destroy_private(event);
 459                 break;
 460         case LTTNG_KERNEL_NOOP:
 461                 break;
 462         default:
 463                 WARN_ON_ONCE(1);
 464         }
 465         list_del(&event->list);
 466         lttng_destroy_context(event->ctx);
 467         kmem_cache_free(event_cache, event);
 468 }
 469
 470 /*
 471  * We have exclusive access to our metadata buffer (protected by the
 472  * sessions_mutex), so we can do racy operations such as looking for
 473  * remaining space left in packet and write, since mutual exclusion
 474  * protects us from concurrent writes.
 475  */
 476 int lttng_metadata_printf(struct lttng_session *session,
 477                           const char *fmt, ...)
 478 {
 479         struct lib_ring_buffer_ctx ctx;
 480         struct lttng_channel *chan = session->metadata;
 481         char *str;
 482         int ret = 0, waitret;
 483         size_t len, reserve_len, pos;
 484         va_list ap;
 485
 486         WARN_ON_ONCE(!ACCESS_ONCE(session->active));
 487
 488         va_start(ap, fmt);
 489         str = kvasprintf(GFP_KERNEL, fmt, ap);
 490         va_end(ap);
 491         if (!str)
 492                 return -ENOMEM;
 493
 494         len = strlen(str);
 495         pos = 0;
 496
 497         for (pos = 0; pos < len; pos += reserve_len) {
 498                 reserve_len = min_t(size_t,
 499                                 chan->ops->packet_avail_size(chan->chan),
 500                                 len - pos);
 501                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 502                                          sizeof(char), -1);
 503                 /*
 504                  * We don't care about metadata buffer's records lost
 505                  * count, because we always retry here. Report error if
 506                  * we need to bail out after timeout or being
 507                  * interrupted.
 508                  */
 509                 waitret = wait_event_interruptible_timeout(*chan->ops->get_writer_buf_wait_queue(chan->chan, -1),
 510                         ({
 511                                 ret = chan->ops->event_reserve(&ctx, 0);
 512                                 ret != -ENOBUFS || !ret;
 513                         }),
 514                         msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC));
 515                 if (!waitret || waitret == -ERESTARTSYS || ret) {
 516                         printk(KERN_WARNING "LTTng: Failure to write metadata to buffers (%s)\n",
 517                                 waitret == -ERESTARTSYS ? "interrupted" :
 518                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 519                         if (waitret == -ERESTARTSYS)
 520                                 ret = waitret;
 521                         goto end;
 522                 }
 523                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 524                 chan->ops->event_commit(&ctx);
 525         }
 526 end:
 527         kfree(str);
 528         return ret;
 529 }
 530
 531 static
 532 int _lttng_field_statedump(struct lttng_session *session,
 533                          const struct lttng_event_field *field)
 534 {
 535         int ret = 0;
 536
 537         switch (field->type.atype) {
 538         case atype_integer:
 539                 ret = lttng_metadata_printf(session,
 540                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 541                         field->type.u.basic.integer.size,
 542                         field->type.u.basic.integer.alignment,
 543                         field->type.u.basic.integer.signedness,
 544                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 545                                 ? "none"
 546                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 547                                         ? "UTF8"
 548                                         : "ASCII",
 549                         field->type.u.basic.integer.base,
 550 #ifdef __BIG_ENDIAN
 551                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 552 #else
 553                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 554 #endif
 555                         field->name);
 556                 break;
 557         case atype_enum:
 558                 ret = lttng_metadata_printf(session,
 559                         "               %s _%s;\n",
 560                         field->type.u.basic.enumeration.name,
 561                         field->name);
 562                 break;
 563         case atype_array:
 564         {
 565                 const struct lttng_basic_type *elem_type;
 566
 567                 elem_type = &field->type.u.array.elem_type;
 568                 ret = lttng_metadata_printf(session,
 569                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 570                         elem_type->u.basic.integer.size,
 571                         elem_type->u.basic.integer.alignment,
 572                         elem_type->u.basic.integer.signedness,
 573                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 574                                 ? "none"
 575                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 576                                         ? "UTF8"
 577                                         : "ASCII",
 578                         elem_type->u.basic.integer.base,
 579 #ifdef __BIG_ENDIAN
 580                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 581 #else
 582                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 583 #endif
 584                         field->name, field->type.u.array.length);
 585                 break;
 586         }
 587         case atype_sequence:
 588         {
 589                 const struct lttng_basic_type *elem_type;
 590                 const struct lttng_basic_type *length_type;
 591
 592                 elem_type = &field->type.u.sequence.elem_type;
 593                 length_type = &field->type.u.sequence.length_type;
 594                 ret = lttng_metadata_printf(session,
 595                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 596                         length_type->u.basic.integer.size,
 597                         (unsigned int) length_type->u.basic.integer.alignment,
 598                         length_type->u.basic.integer.signedness,
 599                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 600                                 ? "none"
 601                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 602                                         ? "UTF8"
 603                                         : "ASCII"),
 604                         length_type->u.basic.integer.base,
 605 #ifdef __BIG_ENDIAN
 606                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 607 #else
 608                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 609 #endif
 610                         field->name);
 611                 if (ret)
 612                         return ret;
 613
 614                 ret = lttng_metadata_printf(session,
 615                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 616                         elem_type->u.basic.integer.size,
 617                         (unsigned int) elem_type->u.basic.integer.alignment,
 618                         elem_type->u.basic.integer.signedness,
 619                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 620                                 ? "none"
 621                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 622                                         ? "UTF8"
 623                                         : "ASCII"),
 624                         elem_type->u.basic.integer.base,
 625 #ifdef __BIG_ENDIAN
 626                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 627 #else
 628                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 629 #endif
 630                         field->name,
 631                         field->name);
 632                 break;
 633         }
 634
 635         case atype_string:
 636                 /* Default encoding is UTF8 */
 637                 ret = lttng_metadata_printf(session,
 638                         "               string%s _%s;\n",
 639                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 640                                 " { encoding = ASCII; }" : "",
 641                         field->name);
 642                 break;
 643         default:
 644                 WARN_ON_ONCE(1);
 645                 return -EINVAL;
 646         }
 647         return ret;
 648 }
 649
 650 static
 651 int _lttng_context_metadata_statedump(struct lttng_session *session,
 652                                     struct lttng_ctx *ctx)
 653 {
 654         int ret = 0;
 655         int i;
 656
 657         if (!ctx)
 658                 return 0;
 659         for (i = 0; i < ctx->nr_fields; i++) {
 660                 const struct lttng_ctx_field *field = &ctx->fields[i];
 661
 662                 ret = _lttng_field_statedump(session, &field->event_field);
 663                 if (ret)
 664                         return ret;
 665         }
 666         return ret;
 667 }
 668
 669 static
 670 int _lttng_fields_metadata_statedump(struct lttng_session *session,
 671                                    struct lttng_event *event)
 672 {
 673         const struct lttng_event_desc *desc = event->desc;
 674         int ret = 0;
 675         int i;
 676
 677         for (i = 0; i < desc->nr_fields; i++) {
 678                 const struct lttng_event_field *field = &desc->fields[i];
 679
 680                 ret = _lttng_field_statedump(session, field);
 681                 if (ret)
 682                         return ret;
 683         }
 684         return ret;
 685 }
 686
 687 static
 688 int _lttng_event_metadata_statedump(struct lttng_session *session,
 689                                   struct lttng_channel *chan,
 690                                   struct lttng_event *event)
 691 {
 692         int ret = 0;
 693
 694         if (event->metadata_dumped || !ACCESS_ONCE(session->active))
 695                 return 0;
 696         if (chan == session->metadata)
 697                 return 0;
 698
 699         ret = lttng_metadata_printf(session,
 700                 "event {\n"
 701                 "       name = %s;\n"
 702                 "       id = %u;\n"
 703                 "       stream_id = %u;\n",
 704                 event->desc->name,
 705                 event->id,
 706                 event->chan->id);
 707         if (ret)
 708                 goto end;
 709
 710         if (event->ctx) {
 711                 ret = lttng_metadata_printf(session,
 712                         "       context := struct {\n");
 713                 if (ret)
 714                         goto end;
 715         }
 716         ret = _lttng_context_metadata_statedump(session, event->ctx);
 717         if (ret)
 718                 goto end;
 719         if (event->ctx) {
 720                 ret = lttng_metadata_printf(session,
 721                         "       };\n");
 722                 if (ret)
 723                         goto end;
 724         }
 725
 726         ret = lttng_metadata_printf(session,
 727                 "       fields := struct {\n"
 728                 );
 729         if (ret)
 730                 goto end;
 731
 732         ret = _lttng_fields_metadata_statedump(session, event);
 733         if (ret)
 734                 goto end;
 735
 736         /*
 737          * LTTng space reservation can only reserve multiples of the
 738          * byte size.
 739          */
 740         ret = lttng_metadata_printf(session,
 741                 "       };\n"
 742                 "};\n\n");
 743         if (ret)
 744                 goto end;
 745
 746         event->metadata_dumped = 1;
 747 end:
 748         return ret;
 749
 750 }
 751
 752 static
 753 int _lttng_channel_metadata_statedump(struct lttng_session *session,
 754                                     struct lttng_channel *chan)
 755 {
 756         int ret = 0;
 757
 758         if (chan->metadata_dumped || !ACCESS_ONCE(session->active))
 759                 return 0;
 760         if (chan == session->metadata)
 761                 return 0;
 762
 763         WARN_ON_ONCE(!chan->header_type);
 764         ret = lttng_metadata_printf(session,
 765                 "stream {\n"
 766                 "       id = %u;\n"
 767                 "       event.header := %s;\n"
 768                 "       packet.context := struct packet_context;\n",
 769                 chan->id,
 770                 chan->header_type == 1 ? "struct event_header_compact" :
 771                         "struct event_header_large");
 772         if (ret)
 773                 goto end;
 774
 775         if (chan->ctx) {
 776                 ret = lttng_metadata_printf(session,
 777                         "       event.context := struct {\n");
 778                 if (ret)
 779                         goto end;
 780         }
 781         ret = _lttng_context_metadata_statedump(session, chan->ctx);
 782         if (ret)
 783                 goto end;
 784         if (chan->ctx) {
 785                 ret = lttng_metadata_printf(session,
 786                         "       };\n");
 787                 if (ret)
 788                         goto end;
 789         }
 790
 791         ret = lttng_metadata_printf(session,
 792                 "};\n\n");
 793
 794         chan->metadata_dumped = 1;
 795 end:
 796         return ret;
 797 }
 798
 799 static
 800 int _lttng_stream_packet_context_declare(struct lttng_session *session)
 801 {
 802         return lttng_metadata_printf(session,
 803                 "struct packet_context {\n"
 804                 "       uint64_clock_monotonic_t timestamp_begin;\n"
 805                 "       uint64_clock_monotonic_t timestamp_end;\n"
 806                 "       uint32_t events_discarded;\n"
 807                 "       uint32_t content_size;\n"
 808                 "       uint32_t packet_size;\n"
 809                 "       uint32_t cpu_id;\n"
 810                 "};\n\n"
 811                 );
 812 }
 813
 814 /*
 815  * Compact header:
 816  * id: range: 0 - 30.
 817  * id 31 is reserved to indicate an extended header.
 818  *
 819  * Large header:
 820  * id: range: 0 - 65534.
 821  * id 65535 is reserved to indicate an extended header.
 822  */
 823 static
 824 int _lttng_event_header_declare(struct lttng_session *session)
 825 {
 826         return lttng_metadata_printf(session,
 827         "struct event_header_compact {\n"
 828         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
 829         "       variant <id> {\n"
 830         "               struct {\n"
 831         "                       uint27_clock_monotonic_t timestamp;\n"
 832         "               } compact;\n"
 833         "               struct {\n"
 834         "                       uint32_t id;\n"
 835         "                       uint64_clock_monotonic_t timestamp;\n"
 836         "               } extended;\n"
 837         "       } v;\n"
 838         "} align(%u);\n"
 839         "\n"
 840         "struct event_header_large {\n"
 841         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
 842         "       variant <id> {\n"
 843         "               struct {\n"
 844         "                       uint32_clock_monotonic_t timestamp;\n"
 845         "               } compact;\n"
 846         "               struct {\n"
 847         "                       uint32_t id;\n"
 848         "                       uint64_clock_monotonic_t timestamp;\n"
 849         "               } extended;\n"
 850         "       } v;\n"
 851         "} align(%u);\n\n",
 852         lttng_alignof(uint32_t) * CHAR_BIT,
 853         lttng_alignof(uint16_t) * CHAR_BIT
 854         );
 855 }
 856
 857  /*
 858  * Approximation of NTP time of day to clock monotonic correlation,
 859  * taken at start of trace.
 860  * Yes, this is only an approximation. Yes, we can (and will) do better
 861  * in future versions.
 862  */
 863 static
 864 uint64_t measure_clock_offset(void)
 865 {
 866         uint64_t offset, monotonic[2], realtime;
 867         struct timespec rts = { 0, 0 };
 868         unsigned long flags;
 869
 870         /* Disable interrupts to increase correlation precision. */
 871         local_irq_save(flags);
 872         monotonic[0] = trace_clock_read64();
 873         getnstimeofday(&rts);
 874         monotonic[1] = trace_clock_read64();
 875         local_irq_restore(flags);
 876
 877         offset = (monotonic[0] + monotonic[1]) >> 1;
 878         realtime = rts.tv_sec * NSEC_PER_SEC;
 879         realtime += rts.tv_nsec;
 880         offset = realtime - offset;
 881         return offset;
 882 }
 883
 884 /*
 885  * Output metadata into this session's metadata buffers.
 886  */
 887 static
 888 int _lttng_session_metadata_statedump(struct lttng_session *session)
 889 {
 890         unsigned char *uuid_c = session->uuid.b;
 891         unsigned char uuid_s[37], clock_uuid_s[BOOT_ID_LEN];
 892         struct lttng_channel *chan;
 893         struct lttng_event *event;
 894         int ret = 0;
 895
 896         if (!ACCESS_ONCE(session->active))
 897                 return 0;
 898         if (session->metadata_dumped)
 899                 goto skip_session;
 900         if (!session->metadata) {
 901                 printk(KERN_WARNING "LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
 902                 return -EPERM;
 903         }
 904
 905         snprintf(uuid_s, sizeof(uuid_s),
 906                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 907                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
 908                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
 909                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
 910                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
 911
 912         ret = lttng_metadata_printf(session,
 913                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
 914                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
 915                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
 916                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
 917                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
 918                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
 919                 "\n"
 920                 "trace {\n"
 921                 "       major = %u;\n"
 922                 "       minor = %u;\n"
 923                 "       uuid = \"%s\";\n"
 924                 "       byte_order = %s;\n"
 925                 "       packet.header := struct {\n"
 926                 "               uint32_t magic;\n"
 927                 "               uint8_t  uuid[16];\n"
 928                 "               uint32_t stream_id;\n"
 929                 "       };\n"
 930                 "};\n\n",
 931                 lttng_alignof(uint8_t) * CHAR_BIT,
 932                 lttng_alignof(uint16_t) * CHAR_BIT,
 933                 lttng_alignof(uint32_t) * CHAR_BIT,
 934                 lttng_alignof(uint64_t) * CHAR_BIT,
 935                 CTF_VERSION_MAJOR,
 936                 CTF_VERSION_MINOR,
 937                 uuid_s,
 938 #ifdef __BIG_ENDIAN
 939                 "be"
 940 #else
 941                 "le"
 942 #endif
 943                 );
 944         if (ret)
 945                 goto end;
 946
 947         ret = lttng_metadata_printf(session,
 948                 "env {\n"
 949                 "       domain = \"%s\";\n"
 950                 "       sysname = \"%s\";\n"
 951                 "       release = \"%s\";\n"
 952                 "       version = \"%s\";\n"
 953                 "};\n\n",
 954                 "kernel",
 955                 utsname()->sysname,
 956                 utsname()->release,
 957                 utsname()->version
 958                 );
 959         if (ret)
 960                 goto end;
 961
 962         ret = lttng_metadata_printf(session,
 963                 "clock {\n"
 964                 "       name = %s;\n",
 965                 "monotonic"
 966                 );
 967         if (ret)
 968                 goto end;
 969
 970         if (!trace_clock_uuid(clock_uuid_s)) {
 971                 ret = lttng_metadata_printf(session,
 972                         "       uuid = \"%s\";\n",
 973                         clock_uuid_s
 974                         );
 975                 if (ret)
 976                         goto end;
 977         }
 978
 979         ret = lttng_metadata_printf(session,
 980                 "       description = \"Monotonic Clock\";\n"
 981                 "       freq = %llu; /* Frequency, in Hz */\n"
 982                 "       /* clock value offset from Epoch is: offset * (1/freq) */\n"
 983                 "       offset = %llu;\n"
 984                 "};\n\n",
 985                 (unsigned long long) trace_clock_freq(),
 986                 (unsigned long long) measure_clock_offset()
 987                 );
 988         if (ret)
 989                 goto end;
 990
 991         ret = lttng_metadata_printf(session,
 992                 "typealias integer {\n"
 993                 "       size = 27; align = 1; signed = false;\n"
 994                 "       map = clock.monotonic.value;\n"
 995                 "} := uint27_clock_monotonic_t;\n"
 996                 "\n"
 997                 "typealias integer {\n"
 998                 "       size = 32; align = %u; signed = false;\n"
 999                 "       map = clock.monotonic.value;\n"
1000                 "} := uint32_clock_monotonic_t;\n"
1001                 "\n"
1002                 "typealias integer {\n"
1003                 "       size = 64; align = %u; signed = false;\n"
1004                 "       map = clock.monotonic.value;\n"
1005                 "} := uint64_clock_monotonic_t;\n\n",
1006                 lttng_alignof(uint32_t) * CHAR_BIT,
1007                 lttng_alignof(uint64_t) * CHAR_BIT
1008                 );
1009         if (ret)
1010                 goto end;
1011
1012         ret = _lttng_stream_packet_context_declare(session);
1013         if (ret)
1014                 goto end;
1015
1016         ret = _lttng_event_header_declare(session);
1017         if (ret)
1018                 goto end;
1019
1020 skip_session:
1021         list_for_each_entry(chan, &session->chan, list) {
1022                 ret = _lttng_channel_metadata_statedump(session, chan);
1023                 if (ret)
1024                         goto end;
1025         }
1026
1027         list_for_each_entry(event, &session->events, list) {
1028                 ret = _lttng_event_metadata_statedump(session, event->chan, event);
1029                 if (ret)
1030                         goto end;
1031         }
1032         session->metadata_dumped = 1;
1033 end:
1034         return ret;
1035 }
1036
1037 /**
1038  * lttng_transport_register - LTT transport registration
1039  * @transport: transport structure
1040  *
1041  * Registers a transport which can be used as output to extract the data out of
1042  * LTTng. The module calling this registration function must ensure that no
1043  * trap-inducing code will be executed by the transport functions. E.g.
1044  * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
1045  * is made visible to the transport function. This registration acts as a
1046  * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
1047  * after its registration must it synchronize the TLBs.
1048  */
1049 void lttng_transport_register(struct lttng_transport *transport)
1050 {
1051         /*
1052          * Make sure no page fault can be triggered by the module about to be
1053          * registered. We deal with this here so we don't have to call
1054          * vmalloc_sync_all() in each module's init.
1055          */
1056         wrapper_vmalloc_sync_all();
1057
1058         mutex_lock(&sessions_mutex);
1059         list_add_tail(&transport->node, &lttng_transport_list);
1060         mutex_unlock(&sessions_mutex);
1061 }
1062 EXPORT_SYMBOL_GPL(lttng_transport_register);
1063
1064 /**
1065  * lttng_transport_unregister - LTT transport unregistration
1066  * @transport: transport structure
1067  */
1068 void lttng_transport_unregister(struct lttng_transport *transport)
1069 {
1070         mutex_lock(&sessions_mutex);
1071         list_del(&transport->node);
1072         mutex_unlock(&sessions_mutex);
1073 }
1074 EXPORT_SYMBOL_GPL(lttng_transport_unregister);
1075
1076 static int __init lttng_events_init(void)
1077 {
1078         int ret;
1079
1080         event_cache = KMEM_CACHE(lttng_event, 0);
1081         if (!event_cache)
1082                 return -ENOMEM;
1083         ret = lttng_abi_init();
1084         if (ret)
1085                 goto error_abi;
1086         return 0;
1087 error_abi:
1088         kmem_cache_destroy(event_cache);
1089         return ret;
1090 }
1091
1092 module_init(lttng_events_init);
1093
1094 static void __exit lttng_events_exit(void)
1095 {
1096         struct lttng_session *session, *tmpsession;
1097
1098         lttng_abi_exit();
1099         list_for_each_entry_safe(session, tmpsession, &sessions, list)
1100                 lttng_session_destroy(session);
1101         kmem_cache_destroy(event_cache);
1102 }
1103
1104 module_exit(lttng_events_exit);
1105
1106 MODULE_LICENSE("GPL and additional rights");
1107 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1108 MODULE_DESCRIPTION("LTTng Events");