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
  26 #include <common/common.h>
  27 #include <common/kernel-ctl/kernel-ctl.h>
  28 #include <common/sessiond-comm/sessiond-comm.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)", lkc->channel->name, lkc->fd);
 173
 174         return 0;
 175
 176 error:
 177         return -1;
 178 }
 179
 180 /*
 181  * Create a kernel event, enable it to the kernel tracer and add it to the
 182  * channel event list of the kernel session.
 183  */
 184 int kernel_create_event(struct lttng_event *ev,
 185                 struct ltt_kernel_channel *channel)
 186 {
 187         int ret;
 188         struct ltt_kernel_event *event;
 189
 190         event = trace_kernel_create_event(ev);
 191         if (event == NULL) {
 192                 ret = -1;
 193                 goto error;
 194         }
 195
 196         ret = kernctl_create_event(channel->fd, event->event);
 197         if (ret < 0) {
 198                 switch (errno) {
 199                 case EEXIST:
 200                         break;
 201                 case ENOSYS:
 202                         WARN("Event type not implemented");
 203                         break;
 204                 default:
 205                         PERROR("create event ioctl");
 206                 }
 207                 ret = -errno;
 208                 goto free_event;
 209         }
 210
 211         /*
 212          * LTTNG_KERNEL_SYSCALL event creation will return 0 on success.
 213          */
 214         if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
 215                 DBG2("Kernel event syscall creation success");
 216                 /*
 217                  * We use fd == -1 to ensure that we never trigger a close of fd
 218                  * 0.
 219                  */
 220                 event->fd = -1;
 221                 goto add_list;
 222         }
 223
 224         event->fd = ret;
 225         /* Prevent fd duplication after execlp() */
 226         ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
 227         if (ret < 0) {
 228                 PERROR("fcntl session fd");
 229         }
 230
 231 add_list:
 232         /* Add event to event list */
 233         cds_list_add(&event->list, &channel->events_list.head);
 234         channel->event_count++;
 235
 236         DBG("Event %s created (fd: %d)", ev->name, event->fd);
 237
 238         return 0;
 239
 240 free_event:
 241         free(event);
 242 error:
 243         return ret;
 244 }
 245
 246 /*
 247  * Disable a kernel channel.
 248  */
 249 int kernel_disable_channel(struct ltt_kernel_channel *chan)
 250 {
 251         int ret;
 252
 253         ret = kernctl_disable(chan->fd);
 254         if (ret < 0) {
 255                 PERROR("disable chan ioctl");
 256                 ret = errno;
 257                 goto error;
 258         }
 259
 260         chan->enabled = 0;
 261         DBG("Kernel channel %s disabled (fd: %d)", chan->channel->name, chan->fd);
 262
 263         return 0;
 264
 265 error:
 266         return ret;
 267 }
 268
 269 /*
 270  * Enable a kernel channel.
 271  */
 272 int kernel_enable_channel(struct ltt_kernel_channel *chan)
 273 {
 274         int ret;
 275
 276         ret = kernctl_enable(chan->fd);
 277         if (ret < 0 && errno != EEXIST) {
 278                 PERROR("Enable kernel chan");
 279                 goto error;
 280         }
 281
 282         chan->enabled = 1;
 283         DBG("Kernel channel %s enabled (fd: %d)", chan->channel->name, chan->fd);
 284
 285         return 0;
 286
 287 error:
 288         return ret;
 289 }
 290
 291 /*
 292  * Enable a kernel event.
 293  */
 294 int kernel_enable_event(struct ltt_kernel_event *event)
 295 {
 296         int ret;
 297
 298         ret = kernctl_enable(event->fd);
 299         if (ret < 0) {
 300                 switch (errno) {
 301                 case EEXIST:
 302                         ret = LTTCOMM_KERN_EVENT_EXIST;
 303                         break;
 304                 default:
 305                         PERROR("enable kernel event");
 306                         break;
 307                 }
 308                 goto error;
 309         }
 310
 311         event->enabled = 1;
 312         DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
 313
 314         return 0;
 315
 316 error:
 317         return ret;
 318 }
 319
 320 /*
 321  * Disable a kernel event.
 322  */
 323 int kernel_disable_event(struct ltt_kernel_event *event)
 324 {
 325         int ret;
 326
 327         ret = kernctl_disable(event->fd);
 328         if (ret < 0) {
 329                 switch (errno) {
 330                 case EEXIST:
 331                         ret = LTTCOMM_KERN_EVENT_EXIST;
 332                         break;
 333                 default:
 334                         PERROR("disable kernel event");
 335                         break;
 336                 }
 337                 goto error;
 338         }
 339
 340         event->enabled = 0;
 341         DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
 342
 343         return 0;
 344
 345 error:
 346         return ret;
 347 }
 348
 349 /*
 350  * Create kernel metadata, open from the kernel tracer and add it to the
 351  * kernel session.
 352  */
 353 int kernel_open_metadata(struct ltt_kernel_session *session, char *path)
 354 {
 355         int ret;
 356         struct ltt_kernel_metadata *lkm;
 357
 358         /* Allocate kernel metadata */
 359         lkm = trace_kernel_create_metadata(path);
 360         if (lkm == NULL) {
 361                 goto error;
 362         }
 363
 364         /* Kernel tracer metadata creation */
 365         ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
 366         if (ret < 0) {
 367                 goto error;
 368         }
 369
 370         lkm->fd = ret;
 371         /* Prevent fd duplication after execlp() */
 372         ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
 373         if (ret < 0) {
 374                 PERROR("fcntl session fd");
 375         }
 376
 377         session->metadata = lkm;
 378
 379         DBG("Kernel metadata opened (fd: %d)", lkm->fd);
 380
 381         return 0;
 382
 383 error:
 384         return -1;
 385 }
 386
 387 /*
 388  * Start tracing session.
 389  */
 390 int kernel_start_session(struct ltt_kernel_session *session)
 391 {
 392         int ret;
 393
 394         ret = kernctl_start_session(session->fd);
 395         if (ret < 0) {
 396                 PERROR("ioctl start session");
 397                 goto error;
 398         }
 399
 400         DBG("Kernel session started");
 401
 402         return 0;
 403
 404 error:
 405         return ret;
 406 }
 407
 408 /*
 409  * Make a kernel wait to make sure in-flight probe have completed.
 410  */
 411 void kernel_wait_quiescent(int fd)
 412 {
 413         int ret;
 414
 415         DBG("Kernel quiescent wait on %d", fd);
 416
 417         ret = kernctl_wait_quiescent(fd);
 418         if (ret < 0) {
 419                 PERROR("wait quiescent ioctl");
 420                 ERR("Kernel quiescent wait failed");
 421         }
 422 }
 423
 424 /*
 425  * Kernel calibrate
 426  */
 427 int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
 428 {
 429         int ret;
 430
 431         ret = kernctl_calibrate(fd, calibrate);
 432         if (ret < 0) {
 433                 PERROR("calibrate ioctl");
 434                 return -1;
 435         }
 436
 437         return 0;
 438 }
 439
 440
 441 /*
 442  *  Force flush buffer of metadata.
 443  */
 444 int kernel_metadata_flush_buffer(int fd)
 445 {
 446         int ret;
 447
 448         ret = kernctl_buffer_flush(fd);
 449         if (ret < 0) {
 450                 ERR("Fail to flush metadata buffers %d (ret: %d)", fd, ret);
 451         }
 452
 453         return 0;
 454 }
 455
 456 /*
 457  * Force flush buffer for channel.
 458  */
 459 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
 460 {
 461         int ret;
 462         struct ltt_kernel_stream *stream;
 463
 464         DBG("Flush buffer for channel %s", channel->channel->name);
 465
 466         cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
 467                 DBG("Flushing channel stream %d", stream->fd);
 468                 ret = kernctl_buffer_flush(stream->fd);
 469                 if (ret < 0) {
 470                         PERROR("ioctl");
 471                         ERR("Fail to flush buffer for stream %d (ret: %d)",
 472                                         stream->fd, ret);
 473                 }
 474         }
 475
 476         return 0;
 477 }
 478
 479 /*
 480  * Stop tracing session.
 481  */
 482 int kernel_stop_session(struct ltt_kernel_session *session)
 483 {
 484         int ret;
 485
 486         ret = kernctl_stop_session(session->fd);
 487         if (ret < 0) {
 488                 goto error;
 489         }
 490
 491         DBG("Kernel session stopped");
 492
 493         return 0;
 494
 495 error:
 496         return ret;
 497 }
 498
 499 /*
 500  * Open stream of channel, register it to the kernel tracer and add it
 501  * to the stream list of the channel.
 502  *
 503  * Return the number of created stream. Else, a negative value.
 504  */
 505 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 506 {
 507         int ret, count = 0;
 508         struct ltt_kernel_stream *lks;
 509
 510         while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
 511                 lks = trace_kernel_create_stream(channel->channel->name, count);
 512                 if (lks == NULL) {
 513                         ret = close(ret);
 514                         if (ret) {
 515                                 PERROR("close");
 516                         }
 517                         goto error;
 518                 }
 519
 520                 lks->fd = ret;
 521                 /* Prevent fd duplication after execlp() */
 522                 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 523                 if (ret < 0) {
 524                         PERROR("fcntl session fd");
 525                 }
 526
 527                 /* Add stream to channe stream list */
 528                 cds_list_add(&lks->list, &channel->stream_list.head);
 529                 channel->stream_count++;
 530
 531                 /* Increment counter which represent CPU number. */
 532                 count++;
 533
 534                 DBG("Kernel stream %s created (fd: %d, state: %d)", lks->name, lks->fd,
 535                                 lks->state);
 536         }
 537
 538         return channel->stream_count;
 539
 540 error:
 541         return -1;
 542 }
 543
 544 /*
 545  * Open the metadata stream and set it to the kernel session.
 546  */
 547 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
 548 {
 549         int ret;
 550
 551         ret = kernctl_create_stream(session->metadata->fd);
 552         if (ret < 0) {
 553                 PERROR("kernel create metadata stream");
 554                 goto error;
 555         }
 556
 557         DBG("Kernel metadata stream created (fd: %d)", ret);
 558         session->metadata_stream_fd = ret;
 559         /* Prevent fd duplication after execlp() */
 560         ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
 561         if (ret < 0) {
 562                 PERROR("fcntl session fd");
 563         }
 564
 565         return 0;
 566
 567 error:
 568         return -1;
 569 }
 570
 571 /*
 572  * Get the event list from the kernel tracer and return the number of elements.
 573  */
 574 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 575 {
 576         int fd, pos, ret;
 577         char *event;
 578         size_t nbmem, count = 0;
 579         ssize_t size;
 580         FILE *fp;
 581         struct lttng_event *elist;
 582
 583         fd = kernctl_tracepoint_list(tracer_fd);
 584         if (fd < 0) {
 585                 PERROR("kernel tracepoint list");
 586                 goto error;
 587         }
 588
 589         fp = fdopen(fd, "r");
 590         if (fp == NULL) {
 591                 PERROR("kernel tracepoint list fdopen");
 592                 goto error_fp;
 593         }
 594
 595         /*
 596          * Init memory size counter
 597          * See kernel-ctl.h for explanation of this value
 598          */
 599         nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
 600         elist = zmalloc(sizeof(struct lttng_event) * nbmem);
 601         if (elist == NULL) {
 602                 PERROR("alloc list events");
 603                 count = -ENOMEM;
 604                 goto end;
 605         }
 606
 607         while ((size = fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos)) == 1) {
 608                 if (count >= nbmem) {
 609                         struct lttng_event *new_elist;
 610
 611                         DBG("Reallocating event list from %zu to %zu bytes", nbmem,
 612                                         nbmem * 2);
 613                         /* Double the size */
 614                         nbmem <<= 1;
 615                         new_elist = realloc(elist, nbmem * sizeof(struct lttng_event));
 616                         if (new_elist == NULL) {
 617                                 PERROR("realloc list events");
 618                                 free(event);
 619                                 free(elist);
 620                                 count = -ENOMEM;
 621                                 goto end;
 622                         }
 623                         elist = new_elist;
 624                 }
 625                 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
 626                 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 627                 elist[count].enabled = -1;
 628                 count++;
 629                 free(event);
 630         }
 631
 632         *events = elist;
 633         DBG("Kernel list events done (%zu events)", count);
 634 end:
 635         ret = fclose(fp);       /* closes both fp and fd */
 636         if (ret) {
 637                 PERROR("fclose");
 638         }
 639         return count;
 640
 641 error_fp:
 642         ret = close(fd);
 643         if (ret) {
 644                 PERROR("close");
 645         }
 646 error:
 647         return -1;
 648 }
 649
 650 /*
 651  * Get kernel version and validate it.
 652  */
 653 int kernel_validate_version(int tracer_fd)
 654 {
 655         int ret;
 656         struct lttng_kernel_tracer_version version;
 657
 658         ret = kernctl_tracer_version(tracer_fd, &version);
 659         if (ret < 0) {
 660                 ERR("Failed at getting the lttng-modules version");
 661                 goto error;
 662         }
 663
 664         /* Validate version */
 665         if (version.major != KERN_MODULES_PRE_MAJOR
 666                 && version.major != KERN_MODULES_MAJOR) {
 667                 goto error_version;
 668         }
 669
 670         DBG2("Kernel tracer version validated (major version %d)", version.major);
 671         return 0;
 672
 673 error_version:
 674         ERR("Kernel major version %d is not compatible (supporting <= %d)",
 675                         version.major, KERN_MODULES_MAJOR)
 676         ret = -1;
 677
 678 error:
 679         return ret;
 680 }
 681
 682 /*
 683  * Kernel work-arounds called at the start of sessiond main().
 684  */
 685 int init_kernel_workarounds(void)
 686 {
 687         int ret;
 688         FILE *fp;
 689
 690         /*
 691          * boot_id needs to be read once before being used concurrently
 692          * to deal with a Linux kernel race. A fix is proposed for
 693          * upstream, but the work-around is needed for older kernels.
 694          */
 695         fp = fopen("/proc/sys/kernel/random/boot_id", "r");
 696         if (!fp) {
 697                 goto end_boot_id;
 698         }
 699         while (!feof(fp)) {
 700                 char buf[37] = "";
 701
 702                 ret = fread(buf, 1, sizeof(buf), fp);
 703                 if (ret < 0) {
 704                         /* Ignore error, we don't really care */
 705                 }
 706         }
 707         ret = fclose(fp);
 708         if (ret) {
 709                 PERROR("fclose");
 710         }
 711 end_boot_id:
 712         return 0;
 713 }