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