src/bin/lttng-sessiond/kernel.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; only version 2
   7  * of the License.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include <common/common.h>
  28 #include <common/kernel-ctl/kernel-ctl.h>
  29
  30 #include "kernel.h"
  31 #include "kern-modules.h"
  32
  33 /*
  34  * Add context on a kernel channel.
  35  */
  36 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
  37                 struct lttng_kernel_context *ctx)
  38 {
  39         int ret;
  40
  41         DBG("Adding context to channel %s", chan->channel->name);
  42         ret = kernctl_add_context(chan->fd, ctx);
  43         if (ret < 0) {
  44                 if (errno != EEXIST) {
  45                         perror("add context ioctl");
  46                 } else {
  47                         /* If EEXIST, we just ignore the error */
  48                         ret = 0;
  49                 }
  50                 goto error;
  51         }
  52
  53         chan->ctx = zmalloc(sizeof(struct lttng_kernel_context));
  54         if (chan->ctx == NULL) {
  55                 perror("zmalloc event context");
  56                 goto error;
  57         }
  58
  59         memcpy(chan->ctx, ctx, sizeof(struct lttng_kernel_context));
  60
  61         return 0;
  62
  63 error:
  64         return ret;
  65 }
  66
  67 /*
  68  * Add context on a kernel event.
  69  */
  70 int kernel_add_event_context(struct ltt_kernel_event *event,
  71                 struct lttng_kernel_context *ctx)
  72 {
  73         int ret;
  74
  75         DBG("Adding context to event %s", event->event->name);
  76         ret = kernctl_add_context(event->fd, ctx);
  77         if (ret < 0) {
  78                 perror("add context ioctl");
  79                 goto error;
  80         }
  81
  82         event->ctx = zmalloc(sizeof(struct lttng_kernel_context));
  83         if (event->ctx == NULL) {
  84                 perror("zmalloc event context");
  85                 goto error;
  86         }
  87
  88         memcpy(event->ctx, ctx, sizeof(struct lttng_kernel_context));
  89
  90         return 0;
  91
  92 error:
  93         return ret;
  94 }
  95
  96 /*
  97  * Create a new kernel session, register it to the kernel tracer and add it to
  98  * the session daemon session.
  99  */
 100 int kernel_create_session(struct ltt_session *session, int tracer_fd)
 101 {
 102         int ret;
 103         struct ltt_kernel_session *lks;
 104
 105         /* Allocate data structure */
 106         lks = trace_kernel_create_session(session->path);
 107         if (lks == NULL) {
 108                 ret = -1;
 109                 goto error;
 110         }
 111
 112         /* Kernel tracer session creation */
 113         ret = kernctl_create_session(tracer_fd);
 114         if (ret < 0) {
 115                 perror("ioctl kernel create session");
 116                 goto error;
 117         }
 118
 119         lks->fd = ret;
 120         /* Prevent fd duplication after execlp() */
 121         ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 122         if (ret < 0) {
 123                 perror("fcntl session fd");
 124         }
 125
 126         lks->consumer_fds_sent = 0;
 127         session->kernel_session = lks;
 128
 129         DBG("Kernel session created (fd: %d)", lks->fd);
 130
 131         return 0;
 132
 133 error:
 134         return ret;
 135 }
 136
 137 /*
 138  * Create a kernel channel, register it to the kernel tracer and add it to the
 139  * kernel session.
 140  */
 141 int kernel_create_channel(struct ltt_kernel_session *session,
 142                 struct lttng_channel *chan, char *path)
 143 {
 144         int ret;
 145         struct ltt_kernel_channel *lkc;
 146
 147         /* Allocate kernel channel */
 148         lkc = trace_kernel_create_channel(chan, path);
 149         if (lkc == NULL) {
 150                 goto error;
 151         }
 152
 153         /* Kernel tracer channel creation */
 154         ret = kernctl_create_channel(session->fd, &lkc->channel->attr);
 155         if (ret < 0) {
 156                 perror("ioctl kernel create channel");
 157                 goto error;
 158         }
 159
 160         /* Setup the channel fd */
 161         lkc->fd = ret;
 162         /* Prevent fd duplication after execlp() */
 163         ret = fcntl(lkc->fd, F_SETFD, FD_CLOEXEC);
 164         if (ret < 0) {
 165                 perror("fcntl session fd");
 166         }
 167
 168         /* Add channel to session */
 169         cds_list_add(&lkc->list, &session->channel_list.head);
 170         session->channel_count++;
 171
 172         DBG("Kernel channel %s created (fd: %d and path: %s)",
 173                         lkc->channel->name, lkc->fd, lkc->pathname);
 174
 175         return 0;
 176
 177 error:
 178         return -1;
 179 }
 180
 181 /*
 182  * Create a kernel event, enable it to the kernel tracer and add it to the
 183  * channel event list of the kernel session.
 184  */
 185 int kernel_create_event(struct lttng_event *ev,
 186                 struct ltt_kernel_channel *channel)
 187 {
 188         int ret;
 189         struct ltt_kernel_event *event;
 190
 191         event = trace_kernel_create_event(ev);
 192         if (event == NULL) {
 193                 ret = -1;
 194                 goto error;
 195         }
 196
 197         ret = kernctl_create_event(channel->fd, event->event);
 198         if (ret < 0) {
 199                 if (errno != EEXIST) {
 200                         PERROR("create event ioctl");
 201                 }
 202                 ret = -errno;
 203                 goto free_event;
 204         }
 205
 206         /*
 207          * LTTNG_KERNEL_SYSCALL event creation will return 0 on success. However
 208          * this FD must not be added to the event list.
 209          */
 210         if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
 211                 DBG2("Kernel event syscall creation success");
 212                 goto end;
 213         }
 214
 215         event->fd = ret;
 216         /* Prevent fd duplication after execlp() */
 217         ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
 218         if (ret < 0) {
 219                 perror("fcntl session fd");
 220         }
 221
 222         /* Add event to event list */
 223         cds_list_add(&event->list, &channel->events_list.head);
 224         channel->event_count++;
 225
 226         DBG("Event %s created (fd: %d)", ev->name, event->fd);
 227
 228 end:
 229         return 0;
 230
 231 free_event:
 232         free(event);
 233 error:
 234         return ret;
 235 }
 236
 237 /*
 238  * Disable a kernel channel.
 239  */
 240 int kernel_disable_channel(struct ltt_kernel_channel *chan)
 241 {
 242         int ret;
 243
 244         ret = kernctl_disable(chan->fd);
 245         if (ret < 0) {
 246                 perror("disable chan ioctl");
 247                 ret = errno;
 248                 goto error;
 249         }
 250
 251         chan->enabled = 0;
 252         DBG("Kernel channel %s disabled (fd: %d)", chan->channel->name, chan->fd);
 253
 254         return 0;
 255
 256 error:
 257         return ret;
 258 }
 259
 260 /*
 261  * Enable a kernel channel.
 262  */
 263 int kernel_enable_channel(struct ltt_kernel_channel *chan)
 264 {
 265         int ret;
 266
 267         ret = kernctl_enable(chan->fd);
 268         if (ret < 0 && errno != EEXIST) {
 269                 perror("Enable kernel chan");
 270                 goto error;
 271         }
 272
 273         chan->enabled = 1;
 274         DBG("Kernel channel %s enabled (fd: %d)", chan->channel->name, chan->fd);
 275
 276         return 0;
 277
 278 error:
 279         return ret;
 280 }
 281
 282 /*
 283  * Enable a kernel event.
 284  */
 285 int kernel_enable_event(struct ltt_kernel_event *event)
 286 {
 287         int ret;
 288
 289         ret = kernctl_enable(event->fd);
 290         if (ret < 0 && errno != EEXIST) {
 291                 perror("enable kernel event");
 292                 goto error;
 293         }
 294
 295         event->enabled = 1;
 296         DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
 297
 298         return 0;
 299
 300 error:
 301         return ret;
 302 }
 303
 304 /*
 305  * Disable a kernel event.
 306  */
 307 int kernel_disable_event(struct ltt_kernel_event *event)
 308 {
 309         int ret;
 310
 311         ret = kernctl_disable(event->fd);
 312         if (ret < 0 && errno != EEXIST) {
 313                 perror("disable kernel event");
 314                 goto error;
 315         }
 316
 317         event->enabled = 0;
 318         DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
 319
 320         return 0;
 321
 322 error:
 323         return ret;
 324 }
 325
 326 /*
 327  * Create kernel metadata, open from the kernel tracer and add it to the
 328  * kernel session.
 329  */
 330 int kernel_open_metadata(struct ltt_kernel_session *session, char *path)
 331 {
 332         int ret;
 333         struct ltt_kernel_metadata *lkm;
 334
 335         /* Allocate kernel metadata */
 336         lkm = trace_kernel_create_metadata(path);
 337         if (lkm == NULL) {
 338                 goto error;
 339         }
 340
 341         /* Kernel tracer metadata creation */
 342         ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
 343         if (ret < 0) {
 344                 goto error;
 345         }
 346
 347         lkm->fd = ret;
 348         /* Prevent fd duplication after execlp() */
 349         ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
 350         if (ret < 0) {
 351                 perror("fcntl session fd");
 352         }
 353
 354         session->metadata = lkm;
 355
 356         DBG("Kernel metadata opened (fd: %d and path: %s)", lkm->fd, lkm->pathname);
 357
 358         return 0;
 359
 360 error:
 361         return -1;
 362 }
 363
 364 /*
 365  * Start tracing session.
 366  */
 367 int kernel_start_session(struct ltt_kernel_session *session)
 368 {
 369         int ret;
 370
 371         ret = kernctl_start_session(session->fd);
 372         if (ret < 0) {
 373                 perror("ioctl start session");
 374                 goto error;
 375         }
 376
 377         DBG("Kernel session started");
 378
 379         return 0;
 380
 381 error:
 382         return ret;
 383 }
 384
 385 /*
 386  * Make a kernel wait to make sure in-flight probe have completed.
 387  */
 388 void kernel_wait_quiescent(int fd)
 389 {
 390         int ret;
 391
 392         DBG("Kernel quiescent wait on %d", fd);
 393
 394         ret = kernctl_wait_quiescent(fd);
 395         if (ret < 0) {
 396                 perror("wait quiescent ioctl");
 397                 ERR("Kernel quiescent wait failed");
 398         }
 399 }
 400
 401 /*
 402  * Kernel calibrate
 403  */
 404 int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
 405 {
 406         int ret;
 407
 408         ret = kernctl_calibrate(fd, calibrate);
 409         if (ret < 0) {
 410                 perror("calibrate ioctl");
 411                 return -1;
 412         }
 413
 414         return 0;
 415 }
 416
 417
 418 /*
 419  *  Force flush buffer of metadata.
 420  */
 421 int kernel_metadata_flush_buffer(int fd)
 422 {
 423         int ret;
 424
 425         ret = kernctl_buffer_flush(fd);
 426         if (ret < 0) {
 427                 ERR("Fail to flush metadata buffers %d (ret: %d", fd, ret);
 428         }
 429
 430         return 0;
 431 }
 432
 433 /*
 434  * Force flush buffer for channel.
 435  */
 436 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
 437 {
 438         int ret;
 439         struct ltt_kernel_stream *stream;
 440
 441         DBG("Flush buffer for channel %s", channel->channel->name);
 442
 443         cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
 444                 DBG("Flushing channel stream %d", stream->fd);
 445                 ret = kernctl_buffer_flush(stream->fd);
 446                 if (ret < 0) {
 447                         perror("ioctl");
 448                         ERR("Fail to flush buffer for stream %d (ret: %d)",
 449                                         stream->fd, ret);
 450                 }
 451         }
 452
 453         return 0;
 454 }
 455
 456 /*
 457  * Stop tracing session.
 458  */
 459 int kernel_stop_session(struct ltt_kernel_session *session)
 460 {
 461         int ret;
 462
 463         ret = kernctl_stop_session(session->fd);
 464         if (ret < 0) {
 465                 goto error;
 466         }
 467
 468         DBG("Kernel session stopped");
 469
 470         return 0;
 471
 472 error:
 473         return ret;
 474 }
 475
 476 /*
 477  * Open stream of channel, register it to the kernel tracer and add it
 478  * to the stream list of the channel.
 479  *
 480  * Return the number of created stream. Else, a negative value.
 481  */
 482 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 483 {
 484         int ret;
 485         struct ltt_kernel_stream *lks;
 486
 487         while ((ret = kernctl_create_stream(channel->fd)) > 0) {
 488                 lks = trace_kernel_create_stream();
 489                 if (lks == NULL) {
 490                         close(ret);
 491                         goto error;
 492                 }
 493
 494                 lks->fd = ret;
 495                 /* Prevent fd duplication after execlp() */
 496                 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 497                 if (ret < 0) {
 498                         perror("fcntl session fd");
 499                 }
 500
 501                 ret = asprintf(&lks->pathname, "%s/%s_%d",
 502                                 channel->pathname, channel->channel->name, channel->stream_count);
 503                 if (ret < 0) {
 504                         perror("asprintf kernel create stream");
 505                         goto error;
 506                 }
 507
 508                 /* Add stream to channe stream list */
 509                 cds_list_add(&lks->list, &channel->stream_list.head);
 510                 channel->stream_count++;
 511
 512                 DBG("Kernel stream %d created (fd: %d, state: %d, path: %s)",
 513                                 channel->stream_count, lks->fd, lks->state, lks->pathname);
 514         }
 515
 516         return channel->stream_count;
 517
 518 error:
 519         return -1;
 520 }
 521
 522 /*
 523  * Open the metadata stream and set it to the kernel session.
 524  */
 525 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
 526 {
 527         int ret;
 528
 529         ret = kernctl_create_stream(session->metadata->fd);
 530         if (ret < 0) {
 531                 perror("kernel create metadata stream");
 532                 goto error;
 533         }
 534
 535         DBG("Kernel metadata stream created (fd: %d)", ret);
 536         session->metadata_stream_fd = ret;
 537         /* Prevent fd duplication after execlp() */
 538         ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
 539         if (ret < 0) {
 540                 perror("fcntl session fd");
 541         }
 542
 543         return 0;
 544
 545 error:
 546         return -1;
 547 }
 548
 549 /*
 550  * Get the event list from the kernel tracer and return the number of elements.
 551  */
 552 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 553 {
 554         int fd, pos;
 555         char *event;
 556         size_t nbmem, count = 0;
 557         ssize_t size;
 558         FILE *fp;
 559         struct lttng_event *elist;
 560
 561         fd = kernctl_tracepoint_list(tracer_fd);
 562         if (fd < 0) {
 563                 perror("kernel tracepoint list");
 564                 goto error;
 565         }
 566
 567         fp = fdopen(fd, "r");
 568         if (fp == NULL) {
 569                 perror("kernel tracepoint list fdopen");
 570                 goto error_fp;
 571         }
 572
 573         /*
 574          * Init memory size counter
 575          * See kernel-ctl.h for explanation of this value
 576          */
 577         nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
 578         elist = zmalloc(sizeof(struct lttng_event) * nbmem);
 579
 580         while ((size = fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos)) == 1) {
 581                 if (count >= nbmem) {
 582                         DBG("Reallocating event list from %zu to %zu bytes", nbmem,
 583                                         nbmem * 2);
 584                         /* Double the size */
 585                         nbmem <<= 1;
 586                         elist = realloc(elist, nbmem * sizeof(struct lttng_event));
 587                         if (elist == NULL) {
 588                                 perror("realloc list events");
 589                                 count = -ENOMEM;
 590                                 goto end;
 591                         }
 592                 }
 593                 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
 594                 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 595                 elist[count].enabled = -1;
 596                 count++;
 597         }
 598
 599         *events = elist;
 600         DBG("Kernel list events done (%zu events)", count);
 601 end:
 602         fclose(fp);     /* closes both fp and fd */
 603         return count;
 604
 605 error_fp:
 606         close(fd);
 607 error:
 608         return -1;
 609 }
 610
 611 /*
 612  * Get kernel version and validate it.
 613  */
 614 int kernel_validate_version(int tracer_fd)
 615 {
 616         int ret;
 617         struct lttng_kernel_tracer_version version;
 618
 619         ret = kernctl_tracer_version(tracer_fd, &version);
 620         if (ret < 0) {
 621                 ERR("Failed at getting the lttng-modules version");
 622                 goto error;
 623         }
 624
 625         /* Validate version */
 626         if (version.version > KERN_MODULES_VERSION) {
 627                 goto error_version;
 628         }
 629
 630         DBG2("Kernel tracer version validated (major version %d)", version.version);
 631         return 0;
 632
 633 error_version:
 634         ERR("Kernel major version %d is not compatible (supporting <= %d)",
 635                         version.version, KERN_MODULES_VERSION)
 636         ret = -1;
 637
 638 error:
 639         return ret;
 640 }
 641
 642 /*
 643  * Kernel work-arounds called at the start of sessiond main().
 644  */
 645 int init_kernel_workarounds(void)
 646 {
 647         int ret;
 648         FILE *fp;
 649
 650         /*
 651          * boot_id needs to be read once before being used concurrently
 652          * to deal with a Linux kernel race. A fix is proposed for
 653          * upstream, but the work-around is needed for older kernels.
 654          */
 655         fp = fopen("/proc/sys/kernel/random/boot_id", "r");
 656         if (!fp) {
 657                 goto end_boot_id;
 658         }
 659         while (!feof(fp)) {
 660                 char buf[37] = "";
 661
 662                 ret = fread(buf, 1, sizeof(buf), fp);
 663                 if (ret < 0) {
 664                         /* Ignore error, we don't really care */
 665                 }
 666         }
 667         fclose(fp);
 668 end_boot_id:
 669
 670         return 0;
 671 }