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