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