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 modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <inttypes.h>
  26
  27 #include <common/common.h>
  28 #include <common/kernel-ctl/kernel-ctl.h>
  29 #include <common/sessiond-comm/sessiond-comm.h>
  30
  31 #include "consumer.h"
  32 #include "kernel.h"
  33 #include "kern-modules.h"
  34
  35 /*
  36  * Add context on a kernel channel.
  37  */
  38 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
  39                 struct lttng_kernel_context *ctx)
  40 {
  41         int ret;
  42
  43         assert(chan);
  44         assert(ctx);
  45
  46         DBG("Adding context to channel %s", chan->channel->name);
  47         ret = kernctl_add_context(chan->fd, ctx);
  48         if (ret < 0) {
  49                 if (errno != EEXIST) {
  50                         PERROR("add context ioctl");
  51                 } else {
  52                         /* If EEXIST, we just ignore the error */
  53                         ret = 0;
  54                 }
  55                 goto error;
  56         }
  57
  58         chan->ctx = zmalloc(sizeof(struct lttng_kernel_context));
  59         if (chan->ctx == NULL) {
  60                 PERROR("zmalloc event context");
  61                 goto error;
  62         }
  63
  64         memcpy(chan->ctx, ctx, sizeof(struct lttng_kernel_context));
  65
  66         return 0;
  67
  68 error:
  69         return ret;
  70 }
  71
  72 /*
  73  * Create a new kernel session, register it to the kernel tracer and add it to
  74  * the session daemon session.
  75  */
  76 int kernel_create_session(struct ltt_session *session, int tracer_fd)
  77 {
  78         int ret;
  79         struct ltt_kernel_session *lks;
  80
  81         assert(session);
  82
  83         /* Allocate data structure */
  84         lks = trace_kernel_create_session();
  85         if (lks == NULL) {
  86                 ret = -1;
  87                 goto error;
  88         }
  89
  90         /* Kernel tracer session creation */
  91         ret = kernctl_create_session(tracer_fd);
  92         if (ret < 0) {
  93                 PERROR("ioctl kernel create session");
  94                 goto error;
  95         }
  96
  97         lks->fd = ret;
  98         /* Prevent fd duplication after execlp() */
  99         ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 100         if (ret < 0) {
 101                 PERROR("fcntl session fd");
 102         }
 103
 104         lks->id = session->id;
 105         lks->consumer_fds_sent = 0;
 106         session->kernel_session = lks;
 107
 108         DBG("Kernel session created (fd: %d)", lks->fd);
 109
 110         return 0;
 111
 112 error:
 113         if (lks) {
 114                 trace_kernel_destroy_session(lks);
 115         }
 116         return ret;
 117 }
 118
 119 /*
 120  * Create a kernel channel, register it to the kernel tracer and add it to the
 121  * kernel session.
 122  */
 123 int kernel_create_channel(struct ltt_kernel_session *session,
 124                 struct lttng_channel *chan)
 125 {
 126         int ret;
 127         struct ltt_kernel_channel *lkc;
 128
 129         assert(session);
 130         assert(chan);
 131
 132         /* Allocate kernel channel */
 133         lkc = trace_kernel_create_channel(chan);
 134         if (lkc == NULL) {
 135                 goto error;
 136         }
 137
 138         DBG3("Kernel create channel %s with attr: %d, %" PRIu64 ", %" PRIu64 ", %u, %u, %d",
 139                         chan->name, lkc->channel->attr.overwrite,
 140                         lkc->channel->attr.subbuf_size, lkc->channel->attr.num_subbuf,
 141                         lkc->channel->attr.switch_timer_interval, lkc->channel->attr.read_timer_interval,
 142                         lkc->channel->attr.output);
 143
 144         /* Kernel tracer channel creation */
 145         ret = kernctl_create_channel(session->fd, &lkc->channel->attr);
 146         if (ret < 0) {
 147                 PERROR("ioctl kernel create channel");
 148                 goto error;
 149         }
 150
 151         /* Setup the channel fd */
 152         lkc->fd = ret;
 153         /* Prevent fd duplication after execlp() */
 154         ret = fcntl(lkc->fd, F_SETFD, FD_CLOEXEC);
 155         if (ret < 0) {
 156                 PERROR("fcntl session fd");
 157         }
 158
 159         /* Add channel to session */
 160         cds_list_add(&lkc->list, &session->channel_list.head);
 161         session->channel_count++;
 162         lkc->session = session;
 163
 164         DBG("Kernel channel %s created (fd: %d)", lkc->channel->name, lkc->fd);
 165
 166         return 0;
 167
 168 error:
 169         if (lkc) {
 170                 free(lkc->channel);
 171                 free(lkc);
 172         }
 173         return -1;
 174 }
 175
 176 /*
 177  * Create a kernel event, enable it to the kernel tracer and add it to the
 178  * channel event list of the kernel session.
 179  */
 180 int kernel_create_event(struct lttng_event *ev,
 181                 struct ltt_kernel_channel *channel)
 182 {
 183         int ret;
 184         struct ltt_kernel_event *event;
 185
 186         assert(ev);
 187         assert(channel);
 188
 189         event = trace_kernel_create_event(ev);
 190         if (event == NULL) {
 191                 ret = -1;
 192                 goto error;
 193         }
 194
 195         ret = kernctl_create_event(channel->fd, event->event);
 196         if (ret < 0) {
 197                 switch (errno) {
 198                 case EEXIST:
 199                         break;
 200                 case ENOSYS:
 201                         WARN("Event type not implemented");
 202                         break;
 203                 default:
 204                         PERROR("create event ioctl");
 205                 }
 206                 ret = -errno;
 207                 goto free_event;
 208         }
 209
 210         /*
 211          * LTTNG_KERNEL_SYSCALL event creation will return 0 on success.
 212          */
 213         if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
 214                 DBG2("Kernel event syscall creation success");
 215                 /*
 216                  * We use fd == -1 to ensure that we never trigger a close of fd
 217                  * 0.
 218                  */
 219                 event->fd = -1;
 220                 goto add_list;
 221         }
 222
 223         event->fd = ret;
 224         /* Prevent fd duplication after execlp() */
 225         ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
 226         if (ret < 0) {
 227                 PERROR("fcntl session fd");
 228         }
 229
 230 add_list:
 231         /* Add event to event list */
 232         cds_list_add(&event->list, &channel->events_list.head);
 233         channel->event_count++;
 234
 235         DBG("Event %s created (fd: %d)", ev->name, event->fd);
 236
 237         return 0;
 238
 239 free_event:
 240         free(event);
 241 error:
 242         return ret;
 243 }
 244
 245 /*
 246  * Disable a kernel channel.
 247  */
 248 int kernel_disable_channel(struct ltt_kernel_channel *chan)
 249 {
 250         int ret;
 251
 252         assert(chan);
 253
 254         ret = kernctl_disable(chan->fd);
 255         if (ret < 0) {
 256                 PERROR("disable chan ioctl");
 257                 ret = errno;
 258                 goto error;
 259         }
 260
 261         chan->enabled = 0;
 262         DBG("Kernel channel %s disabled (fd: %d)", chan->channel->name, chan->fd);
 263
 264         return 0;
 265
 266 error:
 267         return ret;
 268 }
 269
 270 /*
 271  * Enable a kernel channel.
 272  */
 273 int kernel_enable_channel(struct ltt_kernel_channel *chan)
 274 {
 275         int ret;
 276
 277         assert(chan);
 278
 279         ret = kernctl_enable(chan->fd);
 280         if (ret < 0 && errno != EEXIST) {
 281                 PERROR("Enable kernel chan");
 282                 goto error;
 283         }
 284
 285         chan->enabled = 1;
 286         DBG("Kernel channel %s enabled (fd: %d)", chan->channel->name, chan->fd);
 287
 288         return 0;
 289
 290 error:
 291         return ret;
 292 }
 293
 294 /*
 295  * Enable a kernel event.
 296  */
 297 int kernel_enable_event(struct ltt_kernel_event *event)
 298 {
 299         int ret;
 300
 301         assert(event);
 302
 303         ret = kernctl_enable(event->fd);
 304         if (ret < 0) {
 305                 switch (errno) {
 306                 case EEXIST:
 307                         ret = LTTNG_ERR_KERN_EVENT_EXIST;
 308                         break;
 309                 default:
 310                         PERROR("enable kernel event");
 311                         break;
 312                 }
 313                 goto error;
 314         }
 315
 316         event->enabled = 1;
 317         DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
 318
 319         return 0;
 320
 321 error:
 322         return ret;
 323 }
 324
 325 /*
 326  * Disable a kernel event.
 327  */
 328 int kernel_disable_event(struct ltt_kernel_event *event)
 329 {
 330         int ret;
 331
 332         assert(event);
 333
 334         ret = kernctl_disable(event->fd);
 335         if (ret < 0) {
 336                 switch (errno) {
 337                 case EEXIST:
 338                         ret = LTTNG_ERR_KERN_EVENT_EXIST;
 339                         break;
 340                 default:
 341                         PERROR("disable kernel event");
 342                         break;
 343                 }
 344                 goto error;
 345         }
 346
 347         event->enabled = 0;
 348         DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
 349
 350         return 0;
 351
 352 error:
 353         return ret;
 354 }
 355
 356 /*
 357  * Create kernel metadata, open from the kernel tracer and add it to the
 358  * kernel session.
 359  */
 360 int kernel_open_metadata(struct ltt_kernel_session *session)
 361 {
 362         int ret;
 363         struct ltt_kernel_metadata *lkm = NULL;
 364
 365         assert(session);
 366
 367         /* Allocate kernel metadata */
 368         lkm = trace_kernel_create_metadata();
 369         if (lkm == NULL) {
 370                 goto error;
 371         }
 372
 373         /* Kernel tracer metadata creation */
 374         ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
 375         if (ret < 0) {
 376                 goto error_open;
 377         }
 378
 379         lkm->fd = ret;
 380         /* Prevent fd duplication after execlp() */
 381         ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
 382         if (ret < 0) {
 383                 PERROR("fcntl session fd");
 384         }
 385
 386         session->metadata = lkm;
 387
 388         DBG("Kernel metadata opened (fd: %d)", lkm->fd);
 389
 390         return 0;
 391
 392 error_open:
 393         trace_kernel_destroy_metadata(lkm);
 394 error:
 395         return -1;
 396 }
 397
 398 /*
 399  * Start tracing session.
 400  */
 401 int kernel_start_session(struct ltt_kernel_session *session)
 402 {
 403         int ret;
 404
 405         assert(session);
 406
 407         ret = kernctl_start_session(session->fd);
 408         if (ret < 0) {
 409                 PERROR("ioctl start session");
 410                 goto error;
 411         }
 412
 413         DBG("Kernel session started");
 414
 415         return 0;
 416
 417 error:
 418         return ret;
 419 }
 420
 421 /*
 422  * Make a kernel wait to make sure in-flight probe have completed.
 423  */
 424 void kernel_wait_quiescent(int fd)
 425 {
 426         int ret;
 427
 428         DBG("Kernel quiescent wait on %d", fd);
 429
 430         ret = kernctl_wait_quiescent(fd);
 431         if (ret < 0) {
 432                 PERROR("wait quiescent ioctl");
 433                 ERR("Kernel quiescent wait failed");
 434         }
 435 }
 436
 437 /*
 438  * Kernel calibrate
 439  */
 440 int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
 441 {
 442         int ret;
 443
 444         assert(calibrate);
 445
 446         ret = kernctl_calibrate(fd, calibrate);
 447         if (ret < 0) {
 448                 PERROR("calibrate ioctl");
 449                 return -1;
 450         }
 451
 452         return 0;
 453 }
 454
 455
 456 /*
 457  *  Force flush buffer of metadata.
 458  */
 459 int kernel_metadata_flush_buffer(int fd)
 460 {
 461         int ret;
 462
 463         ret = kernctl_buffer_flush(fd);
 464         if (ret < 0) {
 465                 ERR("Fail to flush metadata buffers %d (ret: %d)", fd, ret);
 466         }
 467
 468         return 0;
 469 }
 470
 471 /*
 472  * Force flush buffer for channel.
 473  */
 474 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
 475 {
 476         int ret;
 477         struct ltt_kernel_stream *stream;
 478
 479         assert(channel);
 480
 481         DBG("Flush buffer for channel %s", channel->channel->name);
 482
 483         cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
 484                 DBG("Flushing channel stream %d", stream->fd);
 485                 ret = kernctl_buffer_flush(stream->fd);
 486                 if (ret < 0) {
 487                         PERROR("ioctl");
 488                         ERR("Fail to flush buffer for stream %d (ret: %d)",
 489                                         stream->fd, ret);
 490                 }
 491         }
 492
 493         return 0;
 494 }
 495
 496 /*
 497  * Stop tracing session.
 498  */
 499 int kernel_stop_session(struct ltt_kernel_session *session)
 500 {
 501         int ret;
 502
 503         assert(session);
 504
 505         ret = kernctl_stop_session(session->fd);
 506         if (ret < 0) {
 507                 goto error;
 508         }
 509
 510         DBG("Kernel session stopped");
 511
 512         return 0;
 513
 514 error:
 515         return ret;
 516 }
 517
 518 /*
 519  * Open stream of channel, register it to the kernel tracer and add it
 520  * to the stream list of the channel.
 521  *
 522  * Return the number of created stream. Else, a negative value.
 523  */
 524 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 525 {
 526         int ret, count = 0;
 527         struct ltt_kernel_stream *lks;
 528
 529         assert(channel);
 530
 531         while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
 532                 lks = trace_kernel_create_stream(channel->channel->name, count);
 533                 if (lks == NULL) {
 534                         ret = close(ret);
 535                         if (ret) {
 536                                 PERROR("close");
 537                         }
 538                         goto error;
 539                 }
 540
 541                 lks->fd = ret;
 542                 /* Prevent fd duplication after execlp() */
 543                 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 544                 if (ret < 0) {
 545                         PERROR("fcntl session fd");
 546                 }
 547
 548                 lks->tracefile_size = channel->channel->attr.tracefile_size;
 549                 lks->tracefile_count = channel->channel->attr.tracefile_count;
 550
 551                 /* Add stream to channe stream list */
 552                 cds_list_add(&lks->list, &channel->stream_list.head);
 553                 channel->stream_count++;
 554
 555                 /* Increment counter which represent CPU number. */
 556                 count++;
 557
 558                 DBG("Kernel stream %s created (fd: %d, state: %d)", lks->name, lks->fd,
 559                                 lks->state);
 560         }
 561
 562         return channel->stream_count;
 563
 564 error:
 565         return -1;
 566 }
 567
 568 /*
 569  * Open the metadata stream and set it to the kernel session.
 570  */
 571 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
 572 {
 573         int ret;
 574
 575         assert(session);
 576
 577         ret = kernctl_create_stream(session->metadata->fd);
 578         if (ret < 0) {
 579                 PERROR("kernel create metadata stream");
 580                 goto error;
 581         }
 582
 583         DBG("Kernel metadata stream created (fd: %d)", ret);
 584         session->metadata_stream_fd = ret;
 585         /* Prevent fd duplication after execlp() */
 586         ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
 587         if (ret < 0) {
 588                 PERROR("fcntl session fd");
 589         }
 590
 591         return 0;
 592
 593 error:
 594         return -1;
 595 }
 596
 597 /*
 598  * Get the event list from the kernel tracer and return the number of elements.
 599  */
 600 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 601 {
 602         int fd, pos, ret;
 603         char *event;
 604         size_t nbmem, count = 0;
 605         FILE *fp;
 606         struct lttng_event *elist;
 607
 608         assert(events);
 609
 610         fd = kernctl_tracepoint_list(tracer_fd);
 611         if (fd < 0) {
 612                 PERROR("kernel tracepoint list");
 613                 goto error;
 614         }
 615
 616         fp = fdopen(fd, "r");
 617         if (fp == NULL) {
 618                 PERROR("kernel tracepoint list fdopen");
 619                 goto error_fp;
 620         }
 621
 622         /*
 623          * Init memory size counter
 624          * See kernel-ctl.h for explanation of this value
 625          */
 626         nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
 627         elist = zmalloc(sizeof(struct lttng_event) * nbmem);
 628         if (elist == NULL) {
 629                 PERROR("alloc list events");
 630                 count = -ENOMEM;
 631                 goto end;
 632         }
 633
 634         while (fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos) == 1) {
 635                 if (count >= nbmem) {
 636                         struct lttng_event *new_elist;
 637
 638                         DBG("Reallocating event list from %zu to %zu bytes", nbmem,
 639                                         nbmem * 2);
 640                         /* Double the size */
 641                         nbmem <<= 1;
 642                         new_elist = realloc(elist, nbmem * sizeof(struct lttng_event));
 643                         if (new_elist == NULL) {
 644                                 PERROR("realloc list events");
 645                                 free(event);
 646                                 free(elist);
 647                                 count = -ENOMEM;
 648                                 goto end;
 649                         }
 650                         elist = new_elist;
 651                 }
 652                 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
 653                 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 654                 elist[count].enabled = -1;
 655                 count++;
 656                 free(event);
 657         }
 658
 659         *events = elist;
 660         DBG("Kernel list events done (%zu events)", count);
 661 end:
 662         ret = fclose(fp);       /* closes both fp and fd */
 663         if (ret) {
 664                 PERROR("fclose");
 665         }
 666         return count;
 667
 668 error_fp:
 669         ret = close(fd);
 670         if (ret) {
 671                 PERROR("close");
 672         }
 673 error:
 674         return -1;
 675 }
 676
 677 /*
 678  * Get kernel version and validate it.
 679  */
 680 int kernel_validate_version(int tracer_fd)
 681 {
 682         int ret;
 683         struct lttng_kernel_tracer_version version;
 684
 685         ret = kernctl_tracer_version(tracer_fd, &version);
 686         if (ret < 0) {
 687                 ERR("Failed at getting the lttng-modules version");
 688                 goto error;
 689         }
 690
 691         /* Validate version */
 692         if (version.major != KERN_MODULES_PRE_MAJOR
 693                 && version.major != KERN_MODULES_MAJOR) {
 694                 goto error_version;
 695         }
 696
 697         DBG2("Kernel tracer version validated (major version %d)", version.major);
 698         return 0;
 699
 700 error_version:
 701         ERR("Kernel major version %d is not compatible (supporting <= %d)",
 702                         version.major, KERN_MODULES_MAJOR)
 703         ret = -1;
 704
 705 error:
 706         return ret;
 707 }
 708
 709 /*
 710  * Kernel work-arounds called at the start of sessiond main().
 711  */
 712 int init_kernel_workarounds(void)
 713 {
 714         int ret;
 715         FILE *fp;
 716
 717         /*
 718          * boot_id needs to be read once before being used concurrently
 719          * to deal with a Linux kernel race. A fix is proposed for
 720          * upstream, but the work-around is needed for older kernels.
 721          */
 722         fp = fopen("/proc/sys/kernel/random/boot_id", "r");
 723         if (!fp) {
 724                 goto end_boot_id;
 725         }
 726         while (!feof(fp)) {
 727                 char buf[37] = "";
 728
 729                 ret = fread(buf, 1, sizeof(buf), fp);
 730                 if (ret < 0) {
 731                         /* Ignore error, we don't really care */
 732                 }
 733         }
 734         ret = fclose(fp);
 735         if (ret) {
 736                 PERROR("fclose");
 737         }
 738 end_boot_id:
 739         return 0;
 740 }
 741
 742 /*
 743  * Complete teardown of a kernel session.
 744  */
 745 void kernel_destroy_session(struct ltt_kernel_session *ksess)
 746 {
 747         if (ksess == NULL) {
 748                 DBG3("No kernel session when tearing down session");
 749                 return;
 750         }
 751
 752         DBG("Tearing down kernel session");
 753
 754         /* Close any relayd session */
 755         consumer_output_send_destroy_relayd(ksess->consumer);
 756
 757         trace_kernel_destroy_session(ksess);
 758 }
 759
 760 /*
 761  * Destroy a kernel channel object. It does not do anything on the tracer side.
 762  */
 763 void kernel_destroy_channel(struct ltt_kernel_channel *kchan)
 764 {
 765         struct ltt_kernel_session *ksess = NULL;
 766
 767         assert(kchan);
 768         assert(kchan->channel);
 769
 770         DBG3("Kernel destroy channel %s", kchan->channel->name);
 771
 772         /* Update channel count of associated session. */
 773         if (kchan->session) {
 774                 /* Keep pointer reference so we can update it after the destroy. */
 775                 ksess = kchan->session;
 776         }
 777
 778         trace_kernel_destroy_channel(kchan);
 779
 780         /*
 781          * At this point the kernel channel is not visible anymore. This is safe
 782          * since in order to work on a visible kernel session, the tracing session
 783          * lock (ltt_session.lock) MUST be acquired.
 784          */
 785         if (ksess) {
 786                 ksess->channel_count--;
 787         }
 788 }