lttng-events.c

   1 /*
   2  * lttng-events.c
   3  *
   4  * Holds LTTng per-session event registry.
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/list.h>
  25 #include <linux/mutex.h>
  26 #include <linux/sched.h>
  27 #include <linux/slab.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/utsname.h>
  30 #include "wrapper/uuid.h"
  31 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  32 #include "wrapper/random.h"
  33 #include "lttng-events.h"
  34 #include "lttng-tracer.h"
  35
  36 static LIST_HEAD(sessions);
  37 static LIST_HEAD(lttng_transport_list);
  38 static DEFINE_MUTEX(sessions_mutex);
  39 static struct kmem_cache *event_cache;
  40
  41 static void _lttng_event_destroy(struct lttng_event *event);
  42 static void _lttng_channel_destroy(struct lttng_channel *chan);
  43 static int _lttng_event_unregister(struct lttng_event *event);
  44 static
  45 int _lttng_event_metadata_statedump(struct lttng_session *session,
  46                                   struct lttng_channel *chan,
  47                                   struct lttng_event *event);
  48 static
  49 int _lttng_session_metadata_statedump(struct lttng_session *session);
  50
  51 void synchronize_trace(void)
  52 {
  53         synchronize_sched();
  54 #ifdef CONFIG_PREEMPT_RT
  55         synchronize_rcu();
  56 #endif
  57 }
  58
  59 struct lttng_session *lttng_session_create(void)
  60 {
  61         struct lttng_session *session;
  62
  63         mutex_lock(&sessions_mutex);
  64         session = kzalloc(sizeof(struct lttng_session), GFP_KERNEL);
  65         if (!session)
  66                 return NULL;
  67         INIT_LIST_HEAD(&session->chan);
  68         INIT_LIST_HEAD(&session->events);
  69         uuid_le_gen(&session->uuid);
  70         list_add(&session->list, &sessions);
  71         mutex_unlock(&sessions_mutex);
  72         return session;
  73 }
  74
  75 void lttng_session_destroy(struct lttng_session *session)
  76 {
  77         struct lttng_channel *chan, *tmpchan;
  78         struct lttng_event *event, *tmpevent;
  79         int ret;
  80
  81         mutex_lock(&sessions_mutex);
  82         ACCESS_ONCE(session->active) = 0;
  83         list_for_each_entry(chan, &session->chan, list) {
  84                 ret = lttng_syscalls_unregister(chan);
  85                 WARN_ON(ret);
  86         }
  87         list_for_each_entry(event, &session->events, list) {
  88                 ret = _lttng_event_unregister(event);
  89                 WARN_ON(ret);
  90         }
  91         synchronize_trace();    /* Wait for in-flight events to complete */
  92         list_for_each_entry_safe(event, tmpevent, &session->events, list)
  93                 _lttng_event_destroy(event);
  94         list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
  95                 _lttng_channel_destroy(chan);
  96         list_del(&session->list);
  97         mutex_unlock(&sessions_mutex);
  98         kfree(session);
  99 }
 100
 101 int lttng_session_enable(struct lttng_session *session)
 102 {
 103         int ret = 0;
 104         struct lttng_channel *chan;
 105
 106         mutex_lock(&sessions_mutex);
 107         if (session->active) {
 108                 ret = -EBUSY;
 109                 goto end;
 110         }
 111
 112         /*
 113          * Snapshot the number of events per channel to know the type of header
 114          * we need to use.
 115          */
 116         list_for_each_entry(chan, &session->chan, list) {
 117                 if (chan->header_type)
 118                         continue;               /* don't change it if session stop/restart */
 119                 if (chan->free_event_id < 31)
 120                         chan->header_type = 1;  /* compact */
 121                 else
 122                         chan->header_type = 2;  /* large */
 123         }
 124
 125         ACCESS_ONCE(session->active) = 1;
 126         ACCESS_ONCE(session->been_active) = 1;
 127         ret = _lttng_session_metadata_statedump(session);
 128         if (ret) {
 129                 ACCESS_ONCE(session->active) = 0;
 130                 goto end;
 131         }
 132         ret = lttng_statedump_start(session);
 133         if (ret)
 134                 ACCESS_ONCE(session->active) = 0;
 135 end:
 136         mutex_unlock(&sessions_mutex);
 137         return ret;
 138 }
 139
 140 int lttng_session_disable(struct lttng_session *session)
 141 {
 142         int ret = 0;
 143
 144         mutex_lock(&sessions_mutex);
 145         if (!session->active) {
 146                 ret = -EBUSY;
 147                 goto end;
 148         }
 149         ACCESS_ONCE(session->active) = 0;
 150 end:
 151         mutex_unlock(&sessions_mutex);
 152         return ret;
 153 }
 154
 155 int lttng_channel_enable(struct lttng_channel *channel)
 156 {
 157         int old;
 158
 159         if (channel == channel->session->metadata)
 160                 return -EPERM;
 161         old = xchg(&channel->enabled, 1);
 162         if (old)
 163                 return -EEXIST;
 164         return 0;
 165 }
 166
 167 int lttng_channel_disable(struct lttng_channel *channel)
 168 {
 169         int old;
 170
 171         if (channel == channel->session->metadata)
 172                 return -EPERM;
 173         old = xchg(&channel->enabled, 0);
 174         if (!old)
 175                 return -EEXIST;
 176         return 0;
 177 }
 178
 179 int lttng_event_enable(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, 1);
 186         if (old)
 187                 return -EEXIST;
 188         return 0;
 189 }
 190
 191 int lttng_event_disable(struct lttng_event *event)
 192 {
 193         int old;
 194
 195         if (event->chan == event->chan->session->metadata)
 196                 return -EPERM;
 197         old = xchg(&event->enabled, 0);
 198         if (!old)
 199                 return -EEXIST;
 200         return 0;
 201 }
 202
 203 static struct lttng_transport *lttng_transport_find(const char *name)
 204 {
 205         struct lttng_transport *transport;
 206
 207         list_for_each_entry(transport, &lttng_transport_list, node) {
 208                 if (!strcmp(transport->name, name))
 209                         return transport;
 210         }
 211         return NULL;
 212 }
 213
 214 struct lttng_channel *lttng_channel_create(struct lttng_session *session,
 215                                        const char *transport_name,
 216                                        void *buf_addr,
 217                                        size_t subbuf_size, size_t num_subbuf,
 218                                        unsigned int switch_timer_interval,
 219                                        unsigned int read_timer_interval)
 220 {
 221         struct lttng_channel *chan;
 222         struct lttng_transport *transport = NULL;
 223
 224         mutex_lock(&sessions_mutex);
 225         if (session->been_active)
 226                 goto active;    /* Refuse to add channel to active session */
 227         transport = lttng_transport_find(transport_name);
 228         if (!transport) {
 229                 printk(KERN_WARNING "LTTng transport %s not found\n",
 230                        transport_name);
 231                 goto notransport;
 232         }
 233         if (!try_module_get(transport->owner)) {
 234                 printk(KERN_WARNING "LTT : Can't lock transport module.\n");
 235                 goto notransport;
 236         }
 237         chan = kzalloc(sizeof(struct lttng_channel), GFP_KERNEL);
 238         if (!chan)
 239                 goto nomem;
 240         chan->session = session;
 241         chan->id = session->free_chan_id++;
 242         /*
 243          * Note: the channel creation op already writes into the packet
 244          * headers. Therefore the "chan" information used as input
 245          * should be already accessible.
 246          */
 247         chan->chan = transport->ops.channel_create(transport_name,
 248                         chan, buf_addr, subbuf_size, num_subbuf,
 249                         switch_timer_interval, read_timer_interval);
 250         if (!chan->chan)
 251                 goto create_error;
 252         chan->enabled = 1;
 253         chan->ops = &transport->ops;
 254         chan->transport = transport;
 255         list_add(&chan->list, &session->chan);
 256         mutex_unlock(&sessions_mutex);
 257         return chan;
 258
 259 create_error:
 260         kfree(chan);
 261 nomem:
 262         if (transport)
 263                 module_put(transport->owner);
 264 notransport:
 265 active:
 266         mutex_unlock(&sessions_mutex);
 267         return NULL;
 268 }
 269
 270 /*
 271  * Only used internally at session destruction.
 272  */
 273 static
 274 void _lttng_channel_destroy(struct lttng_channel *chan)
 275 {
 276         chan->ops->channel_destroy(chan->chan);
 277         module_put(chan->transport->owner);
 278         list_del(&chan->list);
 279         lttng_destroy_context(chan->ctx);
 280         kfree(chan);
 281 }
 282
 283 /*
 284  * Supports event creation while tracing session is active.
 285  */
 286 struct lttng_event *lttng_event_create(struct lttng_channel *chan,
 287                                    struct lttng_kernel_event *event_param,
 288                                    void *filter,
 289                                    const struct lttng_event_desc *internal_desc)
 290 {
 291         struct lttng_event *event;
 292         int ret;
 293
 294         mutex_lock(&sessions_mutex);
 295         if (chan->free_event_id == -1U)
 296                 goto full;
 297         /*
 298          * This is O(n^2) (for each event, the loop is called at event
 299          * creation). Might require a hash if we have lots of events.
 300          */
 301         list_for_each_entry(event, &chan->session->events, list)
 302                 if (!strcmp(event->desc->name, event_param->name))
 303                         goto exist;
 304         event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
 305         if (!event)
 306                 goto cache_error;
 307         event->chan = chan;
 308         event->filter = filter;
 309         event->id = chan->free_event_id++;
 310         event->enabled = 1;
 311         event->instrumentation = event_param->instrumentation;
 312         /* Populate lttng_event structure before tracepoint registration. */
 313         smp_wmb();
 314         switch (event_param->instrumentation) {
 315         case LTTNG_KERNEL_TRACEPOINT:
 316                 event->desc = lttng_event_get(event_param->name);
 317                 if (!event->desc)
 318                         goto register_error;
 319                 ret = tracepoint_probe_register(event_param->name,
 320                                 event->desc->probe_callback,
 321                                 event);
 322                 if (ret)
 323                         goto register_error;
 324                 break;
 325         case LTTNG_KERNEL_KPROBE:
 326                 ret = lttng_kprobes_register(event_param->name,
 327                                 event_param->u.kprobe.symbol_name,
 328                                 event_param->u.kprobe.offset,
 329                                 event_param->u.kprobe.addr,
 330                                 event);
 331                 if (ret)
 332                         goto register_error;
 333                 ret = try_module_get(event->desc->owner);
 334                 WARN_ON_ONCE(!ret);
 335                 break;
 336         case LTTNG_KERNEL_KRETPROBE:
 337         {
 338                 struct lttng_event *event_return;
 339
 340                 /* kretprobe defines 2 events */
 341                 event_return =
 342                         kmem_cache_zalloc(event_cache, GFP_KERNEL);
 343                 if (!event_return)
 344                         goto register_error;
 345                 event_return->chan = chan;
 346                 event_return->filter = filter;
 347                 event_return->id = chan->free_event_id++;
 348                 event_return->enabled = 1;
 349                 event_return->instrumentation = event_param->instrumentation;
 350                 /*
 351                  * Populate lttng_event structure before kretprobe registration.
 352                  */
 353                 smp_wmb();
 354                 ret = lttng_kretprobes_register(event_param->name,
 355                                 event_param->u.kretprobe.symbol_name,
 356                                 event_param->u.kretprobe.offset,
 357                                 event_param->u.kretprobe.addr,
 358                                 event, event_return);
 359                 if (ret) {
 360                         kmem_cache_free(event_cache, event_return);
 361                         goto register_error;
 362                 }
 363                 /* Take 2 refs on the module: one per event. */
 364                 ret = try_module_get(event->desc->owner);
 365                 WARN_ON_ONCE(!ret);
 366                 ret = try_module_get(event->desc->owner);
 367                 WARN_ON_ONCE(!ret);
 368                 ret = _lttng_event_metadata_statedump(chan->session, chan,
 369                                                     event_return);
 370                 if (ret) {
 371                         kmem_cache_free(event_cache, event_return);
 372                         module_put(event->desc->owner);
 373                         module_put(event->desc->owner);
 374                         goto statedump_error;
 375                 }
 376                 list_add(&event_return->list, &chan->session->events);
 377                 break;
 378         }
 379         case LTTNG_KERNEL_FUNCTION:
 380                 ret = lttng_ftrace_register(event_param->name,
 381                                 event_param->u.ftrace.symbol_name,
 382                                 event);
 383                 if (ret)
 384                         goto register_error;
 385                 ret = try_module_get(event->desc->owner);
 386                 WARN_ON_ONCE(!ret);
 387                 break;
 388         case LTTNG_KERNEL_NOOP:
 389                 event->desc = internal_desc;
 390                 if (!event->desc)
 391                         goto register_error;
 392                 break;
 393         default:
 394                 WARN_ON_ONCE(1);
 395         }
 396         ret = _lttng_event_metadata_statedump(chan->session, chan, event);
 397         if (ret)
 398                 goto statedump_error;
 399         list_add(&event->list, &chan->session->events);
 400         mutex_unlock(&sessions_mutex);
 401         return event;
 402
 403 statedump_error:
 404         /* If a statedump error occurs, events will not be readable. */
 405 register_error:
 406         kmem_cache_free(event_cache, event);
 407 cache_error:
 408 exist:
 409 full:
 410         mutex_unlock(&sessions_mutex);
 411         return NULL;
 412 }
 413
 414 /*
 415  * Only used internally at session destruction.
 416  */
 417 int _lttng_event_unregister(struct lttng_event *event)
 418 {
 419         int ret = -EINVAL;
 420
 421         switch (event->instrumentation) {
 422         case LTTNG_KERNEL_TRACEPOINT:
 423                 ret = tracepoint_probe_unregister(event->desc->name,
 424                                                   event->desc->probe_callback,
 425                                                   event);
 426                 if (ret)
 427                         return ret;
 428                 break;
 429         case LTTNG_KERNEL_KPROBE:
 430                 lttng_kprobes_unregister(event);
 431                 ret = 0;
 432                 break;
 433         case LTTNG_KERNEL_KRETPROBE:
 434                 lttng_kretprobes_unregister(event);
 435                 ret = 0;
 436                 break;
 437         case LTTNG_KERNEL_FUNCTION:
 438                 lttng_ftrace_unregister(event);
 439                 ret = 0;
 440                 break;
 441         case LTTNG_KERNEL_NOOP:
 442                 ret = 0;
 443                 break;
 444         default:
 445                 WARN_ON_ONCE(1);
 446         }
 447         return ret;
 448 }
 449
 450 /*
 451  * Only used internally at session destruction.
 452  */
 453 static
 454 void _lttng_event_destroy(struct lttng_event *event)
 455 {
 456         switch (event->instrumentation) {
 457         case LTTNG_KERNEL_TRACEPOINT:
 458                 lttng_event_put(event->desc);
 459                 break;
 460         case LTTNG_KERNEL_KPROBE:
 461                 module_put(event->desc->owner);
 462                 lttng_kprobes_destroy_private(event);
 463                 break;
 464         case LTTNG_KERNEL_KRETPROBE:
 465                 module_put(event->desc->owner);
 466                 lttng_kretprobes_destroy_private(event);
 467                 break;
 468         case LTTNG_KERNEL_FUNCTION:
 469                 module_put(event->desc->owner);
 470                 lttng_ftrace_destroy_private(event);
 471                 break;
 472         case LTTNG_KERNEL_NOOP:
 473                 break;
 474         default:
 475                 WARN_ON_ONCE(1);
 476         }
 477         list_del(&event->list);
 478         lttng_destroy_context(event->ctx);
 479         kmem_cache_free(event_cache, event);
 480 }
 481
 482 /*
 483  * We have exclusive access to our metadata buffer (protected by the
 484  * sessions_mutex), so we can do racy operations such as looking for
 485  * remaining space left in packet and write, since mutual exclusion
 486  * protects us from concurrent writes.
 487  */
 488 int lttng_metadata_printf(struct lttng_session *session,
 489                           const char *fmt, ...)
 490 {
 491         struct lib_ring_buffer_ctx ctx;
 492         struct lttng_channel *chan = session->metadata;
 493         char *str;
 494         int ret = 0, waitret;
 495         size_t len, reserve_len, pos;
 496         va_list ap;
 497
 498         WARN_ON_ONCE(!ACCESS_ONCE(session->active));
 499
 500         va_start(ap, fmt);
 501         str = kvasprintf(GFP_KERNEL, fmt, ap);
 502         va_end(ap);
 503         if (!str)
 504                 return -ENOMEM;
 505
 506         len = strlen(str);
 507         pos = 0;
 508
 509         for (pos = 0; pos < len; pos += reserve_len) {
 510                 reserve_len = min_t(size_t,
 511                                 chan->ops->packet_avail_size(chan->chan),
 512                                 len - pos);
 513                 lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
 514                                          sizeof(char), -1);
 515                 /*
 516                  * We don't care about metadata buffer's records lost
 517                  * count, because we always retry here. Report error if
 518                  * we need to bail out after timeout or being
 519                  * interrupted.
 520                  */
 521                 waitret = wait_event_interruptible_timeout(*chan->ops->get_writer_buf_wait_queue(chan->chan, -1),
 522                         ({
 523                                 ret = chan->ops->event_reserve(&ctx, 0);
 524                                 ret != -ENOBUFS || !ret;
 525                         }),
 526                         msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC));
 527                 if (!waitret || waitret == -ERESTARTSYS || ret) {
 528                         printk(KERN_WARNING "LTTng: Failure to write metadata to buffers (%s)\n",
 529                                 waitret == -ERESTARTSYS ? "interrupted" :
 530                                         (ret == -ENOBUFS ? "timeout" : "I/O error"));
 531                         if (waitret == -ERESTARTSYS)
 532                                 ret = waitret;
 533                         goto end;
 534                 }
 535                 chan->ops->event_write(&ctx, &str[pos], reserve_len);
 536                 chan->ops->event_commit(&ctx);
 537         }
 538 end:
 539         kfree(str);
 540         return ret;
 541 }
 542
 543 static
 544 int _lttng_field_statedump(struct lttng_session *session,
 545                          const struct lttng_event_field *field)
 546 {
 547         int ret = 0;
 548
 549         switch (field->type.atype) {
 550         case atype_integer:
 551                 ret = lttng_metadata_printf(session,
 552                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s;\n",
 553                         field->type.u.basic.integer.size,
 554                         field->type.u.basic.integer.alignment,
 555                         field->type.u.basic.integer.signedness,
 556                         (field->type.u.basic.integer.encoding == lttng_encode_none)
 557                                 ? "none"
 558                                 : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
 559                                         ? "UTF8"
 560                                         : "ASCII",
 561                         field->type.u.basic.integer.base,
 562 #ifdef __BIG_ENDIAN
 563                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 564 #else
 565                         field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 566 #endif
 567                         field->name);
 568                 break;
 569         case atype_enum:
 570                 ret = lttng_metadata_printf(session,
 571                         "               %s _%s;\n",
 572                         field->type.u.basic.enumeration.name,
 573                         field->name);
 574                 break;
 575         case atype_array:
 576         {
 577                 const struct lttng_basic_type *elem_type;
 578
 579                 elem_type = &field->type.u.array.elem_type;
 580                 ret = lttng_metadata_printf(session,
 581                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[%u];\n",
 582                         elem_type->u.basic.integer.size,
 583                         elem_type->u.basic.integer.alignment,
 584                         elem_type->u.basic.integer.signedness,
 585                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 586                                 ? "none"
 587                                 : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 588                                         ? "UTF8"
 589                                         : "ASCII",
 590                         elem_type->u.basic.integer.base,
 591 #ifdef __BIG_ENDIAN
 592                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 593 #else
 594                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 595 #endif
 596                         field->name, field->type.u.array.length);
 597                 break;
 598         }
 599         case atype_sequence:
 600         {
 601                 const struct lttng_basic_type *elem_type;
 602                 const struct lttng_basic_type *length_type;
 603
 604                 elem_type = &field->type.u.sequence.elem_type;
 605                 length_type = &field->type.u.sequence.length_type;
 606                 ret = lttng_metadata_printf(session,
 607                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
 608                         length_type->u.basic.integer.size,
 609                         (unsigned int) length_type->u.basic.integer.alignment,
 610                         length_type->u.basic.integer.signedness,
 611                         (length_type->u.basic.integer.encoding == lttng_encode_none)
 612                                 ? "none"
 613                                 : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
 614                                         ? "UTF8"
 615                                         : "ASCII"),
 616                         length_type->u.basic.integer.base,
 617 #ifdef __BIG_ENDIAN
 618                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 619 #else
 620                         length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 621 #endif
 622                         field->name);
 623                 if (ret)
 624                         return ret;
 625
 626                 ret = lttng_metadata_printf(session,
 627                         "               integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } _%s[ __%s_length ];\n",
 628                         elem_type->u.basic.integer.size,
 629                         (unsigned int) elem_type->u.basic.integer.alignment,
 630                         elem_type->u.basic.integer.signedness,
 631                         (elem_type->u.basic.integer.encoding == lttng_encode_none)
 632                                 ? "none"
 633                                 : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
 634                                         ? "UTF8"
 635                                         : "ASCII"),
 636                         elem_type->u.basic.integer.base,
 637 #ifdef __BIG_ENDIAN
 638                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
 639 #else
 640                         elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
 641 #endif
 642                         field->name,
 643                         field->name);
 644                 break;
 645         }
 646
 647         case atype_string:
 648                 /* Default encoding is UTF8 */
 649                 ret = lttng_metadata_printf(session,
 650                         "               string%s _%s;\n",
 651                         field->type.u.basic.string.encoding == lttng_encode_ASCII ?
 652                                 " { encoding = ASCII; }" : "",
 653                         field->name);
 654                 break;
 655         default:
 656                 WARN_ON_ONCE(1);
 657                 return -EINVAL;
 658         }
 659         return ret;
 660 }
 661
 662 static
 663 int _lttng_context_metadata_statedump(struct lttng_session *session,
 664                                     struct lttng_ctx *ctx)
 665 {
 666         int ret = 0;
 667         int i;
 668
 669         if (!ctx)
 670                 return 0;
 671         for (i = 0; i < ctx->nr_fields; i++) {
 672                 const struct lttng_ctx_field *field = &ctx->fields[i];
 673
 674                 ret = _lttng_field_statedump(session, &field->event_field);
 675                 if (ret)
 676                         return ret;
 677         }
 678         return ret;
 679 }
 680
 681 static
 682 int _lttng_fields_metadata_statedump(struct lttng_session *session,
 683                                    struct lttng_event *event)
 684 {
 685         const struct lttng_event_desc *desc = event->desc;
 686         int ret = 0;
 687         int i;
 688
 689         for (i = 0; i < desc->nr_fields; i++) {
 690                 const struct lttng_event_field *field = &desc->fields[i];
 691
 692                 ret = _lttng_field_statedump(session, field);
 693                 if (ret)
 694                         return ret;
 695         }
 696         return ret;
 697 }
 698
 699 static
 700 int _lttng_event_metadata_statedump(struct lttng_session *session,
 701                                   struct lttng_channel *chan,
 702                                   struct lttng_event *event)
 703 {
 704         int ret = 0;
 705
 706         if (event->metadata_dumped || !ACCESS_ONCE(session->active))
 707                 return 0;
 708         if (chan == session->metadata)
 709                 return 0;
 710
 711         ret = lttng_metadata_printf(session,
 712                 "event {\n"
 713                 "       name = %s;\n"
 714                 "       id = %u;\n"
 715                 "       stream_id = %u;\n",
 716                 event->desc->name,
 717                 event->id,
 718                 event->chan->id);
 719         if (ret)
 720                 goto end;
 721
 722         if (event->ctx) {
 723                 ret = lttng_metadata_printf(session,
 724                         "       context := struct {\n");
 725                 if (ret)
 726                         goto end;
 727         }
 728         ret = _lttng_context_metadata_statedump(session, event->ctx);
 729         if (ret)
 730                 goto end;
 731         if (event->ctx) {
 732                 ret = lttng_metadata_printf(session,
 733                         "       };\n");
 734                 if (ret)
 735                         goto end;
 736         }
 737
 738         ret = lttng_metadata_printf(session,
 739                 "       fields := struct {\n"
 740                 );
 741         if (ret)
 742                 goto end;
 743
 744         ret = _lttng_fields_metadata_statedump(session, event);
 745         if (ret)
 746                 goto end;
 747
 748         /*
 749          * LTTng space reservation can only reserve multiples of the
 750          * byte size.
 751          */
 752         ret = lttng_metadata_printf(session,
 753                 "       };\n"
 754                 "};\n\n");
 755         if (ret)
 756                 goto end;
 757
 758         event->metadata_dumped = 1;
 759 end:
 760         return ret;
 761
 762 }
 763
 764 static
 765 int _lttng_channel_metadata_statedump(struct lttng_session *session,
 766                                     struct lttng_channel *chan)
 767 {
 768         int ret = 0;
 769
 770         if (chan->metadata_dumped || !ACCESS_ONCE(session->active))
 771                 return 0;
 772         if (chan == session->metadata)
 773                 return 0;
 774
 775         WARN_ON_ONCE(!chan->header_type);
 776         ret = lttng_metadata_printf(session,
 777                 "stream {\n"
 778                 "       id = %u;\n"
 779                 "       event.header := %s;\n"
 780                 "       packet.context := struct packet_context;\n",
 781                 chan->id,
 782                 chan->header_type == 1 ? "struct event_header_compact" :
 783                         "struct event_header_large");
 784         if (ret)
 785                 goto end;
 786
 787         if (chan->ctx) {
 788                 ret = lttng_metadata_printf(session,
 789                         "       event.context := struct {\n");
 790                 if (ret)
 791                         goto end;
 792         }
 793         ret = _lttng_context_metadata_statedump(session, chan->ctx);
 794         if (ret)
 795                 goto end;
 796         if (chan->ctx) {
 797                 ret = lttng_metadata_printf(session,
 798                         "       };\n");
 799                 if (ret)
 800                         goto end;
 801         }
 802
 803         ret = lttng_metadata_printf(session,
 804                 "};\n\n");
 805
 806         chan->metadata_dumped = 1;
 807 end:
 808         return ret;
 809 }
 810
 811 static
 812 int _lttng_stream_packet_context_declare(struct lttng_session *session)
 813 {
 814         return lttng_metadata_printf(session,
 815                 "struct packet_context {\n"
 816                 "       uint64_clock_monotonic_t timestamp_begin;\n"
 817                 "       uint64_clock_monotonic_t timestamp_end;\n"
 818                 "       uint32_t events_discarded;\n"
 819                 "       uint32_t content_size;\n"
 820                 "       uint32_t packet_size;\n"
 821                 "       uint32_t cpu_id;\n"
 822                 "};\n\n"
 823                 );
 824 }
 825
 826 /*
 827  * Compact header:
 828  * id: range: 0 - 30.
 829  * id 31 is reserved to indicate an extended header.
 830  *
 831  * Large header:
 832  * id: range: 0 - 65534.
 833  * id 65535 is reserved to indicate an extended header.
 834  */
 835 static
 836 int _lttng_event_header_declare(struct lttng_session *session)
 837 {
 838         return lttng_metadata_printf(session,
 839         "struct event_header_compact {\n"
 840         "       enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
 841         "       variant <id> {\n"
 842         "               struct {\n"
 843         "                       uint27_clock_monotonic_t timestamp;\n"
 844         "               } compact;\n"
 845         "               struct {\n"
 846         "                       uint32_t id;\n"
 847         "                       uint64_clock_monotonic_t timestamp;\n"
 848         "               } extended;\n"
 849         "       } v;\n"
 850         "} align(%u);\n"
 851         "\n"
 852         "struct event_header_large {\n"
 853         "       enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
 854         "       variant <id> {\n"
 855         "               struct {\n"
 856         "                       uint32_clock_monotonic_t timestamp;\n"
 857         "               } compact;\n"
 858         "               struct {\n"
 859         "                       uint32_t id;\n"
 860         "                       uint64_clock_monotonic_t timestamp;\n"
 861         "               } extended;\n"
 862         "       } v;\n"
 863         "} align(%u);\n\n",
 864         lttng_alignof(uint32_t) * CHAR_BIT,
 865         lttng_alignof(uint16_t) * CHAR_BIT
 866         );
 867 }
 868
 869  /*
 870  * Approximation of NTP time of day to clock monotonic correlation,
 871  * taken at start of trace.
 872  * Yes, this is only an approximation. Yes, we can (and will) do better
 873  * in future versions.
 874  */
 875 static
 876 uint64_t measure_clock_offset(void)
 877 {
 878         uint64_t offset, monotonic[2], realtime;
 879         struct timespec rts = { 0, 0 };
 880         unsigned long flags;
 881
 882         /* Disable interrupts to increase correlation precision. */
 883         local_irq_save(flags);
 884         monotonic[0] = trace_clock_read64();
 885         getnstimeofday(&rts);
 886         monotonic[1] = trace_clock_read64();
 887         local_irq_restore(flags);
 888
 889         offset = (monotonic[0] + monotonic[1]) >> 1;
 890         realtime = (uint64_t) rts.tv_sec * NSEC_PER_SEC;
 891         realtime += rts.tv_nsec;
 892         offset = realtime - offset;
 893         return offset;
 894 }
 895
 896 /*
 897  * Output metadata into this session's metadata buffers.
 898  */
 899 static
 900 int _lttng_session_metadata_statedump(struct lttng_session *session)
 901 {
 902         unsigned char *uuid_c = session->uuid.b;
 903         unsigned char uuid_s[37], clock_uuid_s[BOOT_ID_LEN];
 904         struct lttng_channel *chan;
 905         struct lttng_event *event;
 906         int ret = 0;
 907
 908         if (!ACCESS_ONCE(session->active))
 909                 return 0;
 910         if (session->metadata_dumped)
 911                 goto skip_session;
 912         if (!session->metadata) {
 913                 printk(KERN_WARNING "LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
 914                 return -EPERM;
 915         }
 916
 917         snprintf(uuid_s, sizeof(uuid_s),
 918                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 919                 uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
 920                 uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
 921                 uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
 922                 uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
 923
 924         ret = lttng_metadata_printf(session,
 925                 "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
 926                 "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
 927                 "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
 928                 "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
 929                 "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
 930                 "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
 931                 "\n"
 932                 "trace {\n"
 933                 "       major = %u;\n"
 934                 "       minor = %u;\n"
 935                 "       uuid = \"%s\";\n"
 936                 "       byte_order = %s;\n"
 937                 "       packet.header := struct {\n"
 938                 "               uint32_t magic;\n"
 939                 "               uint8_t  uuid[16];\n"
 940                 "               uint32_t stream_id;\n"
 941                 "       };\n"
 942                 "};\n\n",
 943                 lttng_alignof(uint8_t) * CHAR_BIT,
 944                 lttng_alignof(uint16_t) * CHAR_BIT,
 945                 lttng_alignof(uint32_t) * CHAR_BIT,
 946                 lttng_alignof(uint64_t) * CHAR_BIT,
 947                 CTF_SPEC_MAJOR,
 948                 CTF_SPEC_MINOR,
 949                 uuid_s,
 950 #ifdef __BIG_ENDIAN
 951                 "be"
 952 #else
 953                 "le"
 954 #endif
 955                 );
 956         if (ret)
 957                 goto end;
 958
 959         ret = lttng_metadata_printf(session,
 960                 "env {\n"
 961                 "       domain = \"kernel\";\n"
 962                 "       sysname = \"%s\";\n"
 963                 "       kernel_release = \"%s\";\n"
 964                 "       kernel_version = \"%s\";\n"
 965                 "       tracer_name = \"lttng-modules\";\n"
 966                 "       tracer_major = %d;\n"
 967                 "       tracer_minor = %d;\n"
 968                 "       tracer_patchlevel = %d;\n"
 969                 "};\n\n",
 970                 utsname()->sysname,
 971                 utsname()->release,
 972                 utsname()->version,
 973                 LTTNG_MODULES_MAJOR_VERSION,
 974                 LTTNG_MODULES_MINOR_VERSION,
 975                 LTTNG_MODULES_PATCHLEVEL_VERSION
 976                 );
 977         if (ret)
 978                 goto end;
 979
 980         ret = lttng_metadata_printf(session,
 981                 "clock {\n"
 982                 "       name = %s;\n",
 983                 "monotonic"
 984                 );
 985         if (ret)
 986                 goto end;
 987
 988         if (!trace_clock_uuid(clock_uuid_s)) {
 989                 ret = lttng_metadata_printf(session,
 990                         "       uuid = \"%s\";\n",
 991                         clock_uuid_s
 992                         );
 993                 if (ret)
 994                         goto end;
 995         }
 996
 997         ret = lttng_metadata_printf(session,
 998                 "       description = \"Monotonic Clock\";\n"
 999                 "       freq = %llu; /* Frequency, in Hz */\n"
1000                 "       /* clock value offset from Epoch is: offset * (1/freq) */\n"
1001                 "       offset = %llu;\n"
1002                 "};\n\n",
1003                 (unsigned long long) trace_clock_freq(),
1004                 (unsigned long long) measure_clock_offset()
1005                 );
1006         if (ret)
1007                 goto end;
1008
1009         ret = lttng_metadata_printf(session,
1010                 "typealias integer {\n"
1011                 "       size = 27; align = 1; signed = false;\n"
1012                 "       map = clock.monotonic.value;\n"
1013                 "} := uint27_clock_monotonic_t;\n"
1014                 "\n"
1015                 "typealias integer {\n"
1016                 "       size = 32; align = %u; signed = false;\n"
1017                 "       map = clock.monotonic.value;\n"
1018                 "} := uint32_clock_monotonic_t;\n"
1019                 "\n"
1020                 "typealias integer {\n"
1021                 "       size = 64; align = %u; signed = false;\n"
1022                 "       map = clock.monotonic.value;\n"
1023                 "} := uint64_clock_monotonic_t;\n\n",
1024                 lttng_alignof(uint32_t) * CHAR_BIT,
1025                 lttng_alignof(uint64_t) * CHAR_BIT
1026                 );
1027         if (ret)
1028                 goto end;
1029
1030         ret = _lttng_stream_packet_context_declare(session);
1031         if (ret)
1032                 goto end;
1033
1034         ret = _lttng_event_header_declare(session);
1035         if (ret)
1036                 goto end;
1037
1038 skip_session:
1039         list_for_each_entry(chan, &session->chan, list) {
1040                 ret = _lttng_channel_metadata_statedump(session, chan);
1041                 if (ret)
1042                         goto end;
1043         }
1044
1045         list_for_each_entry(event, &session->events, list) {
1046                 ret = _lttng_event_metadata_statedump(session, event->chan, event);
1047                 if (ret)
1048                         goto end;
1049         }
1050         session->metadata_dumped = 1;
1051 end:
1052         return ret;
1053 }
1054
1055 /**
1056  * lttng_transport_register - LTT transport registration
1057  * @transport: transport structure
1058  *
1059  * Registers a transport which can be used as output to extract the data out of
1060  * LTTng. The module calling this registration function must ensure that no
1061  * trap-inducing code will be executed by the transport functions. E.g.
1062  * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
1063  * is made visible to the transport function. This registration acts as a
1064  * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
1065  * after its registration must it synchronize the TLBs.
1066  */
1067 void lttng_transport_register(struct lttng_transport *transport)
1068 {
1069         /*
1070          * Make sure no page fault can be triggered by the module about to be
1071          * registered. We deal with this here so we don't have to call
1072          * vmalloc_sync_all() in each module's init.
1073          */
1074         wrapper_vmalloc_sync_all();
1075
1076         mutex_lock(&sessions_mutex);
1077         list_add_tail(&transport->node, &lttng_transport_list);
1078         mutex_unlock(&sessions_mutex);
1079 }
1080 EXPORT_SYMBOL_GPL(lttng_transport_register);
1081
1082 /**
1083  * lttng_transport_unregister - LTT transport unregistration
1084  * @transport: transport structure
1085  */
1086 void lttng_transport_unregister(struct lttng_transport *transport)
1087 {
1088         mutex_lock(&sessions_mutex);
1089         list_del(&transport->node);
1090         mutex_unlock(&sessions_mutex);
1091 }
1092 EXPORT_SYMBOL_GPL(lttng_transport_unregister);
1093
1094 static int __init lttng_events_init(void)
1095 {
1096         int ret;
1097
1098         event_cache = KMEM_CACHE(lttng_event, 0);
1099         if (!event_cache)
1100                 return -ENOMEM;
1101         ret = lttng_abi_init();
1102         if (ret)
1103                 goto error_abi;
1104         return 0;
1105 error_abi:
1106         kmem_cache_destroy(event_cache);
1107         return ret;
1108 }
1109
1110 module_init(lttng_events_init);
1111
1112 static void __exit lttng_events_exit(void)
1113 {
1114         struct lttng_session *session, *tmpsession;
1115
1116         lttng_abi_exit();
1117         list_for_each_entry_safe(session, tmpsession, &sessions, list)
1118                 lttng_session_destroy(session);
1119         kmem_cache_destroy(event_cache);
1120 }
1121
1122 module_exit(lttng_events_exit);
1123
1124 MODULE_LICENSE("GPL and additional rights");
1125 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1126 MODULE_DESCRIPTION("LTTng Events");