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                 switch (errno) {
 200                 case EEXIST:
 201                         break;
 202                 case ENOSYS:
 203                         WARN("Event type not implemented");
 204                         break;
 205                 default:
 206                         PERROR("create event ioctl");
 207                 }
 208                 ret = -errno;
 209                 goto free_event;
 210         }
 211
 212         /*
 213          * LTTNG_KERNEL_SYSCALL event creation will return 0 on success.
 214          */
 215         if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
 216                 DBG2("Kernel event syscall creation success");
 217                 /*
 218                  * We use fd == -1 to ensure that we never trigger a close of fd
 219                  * 0.
 220                  */
 221                 event->fd = -1;
 222                 goto add_list;
 223         }
 224
 225         event->fd = ret;
 226         /* Prevent fd duplication after execlp() */
 227         ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
 228         if (ret < 0) {
 229                 PERROR("fcntl session fd");
 230         }
 231
 232 add_list:
 233         /* Add event to event list */
 234         cds_list_add(&event->list, &channel->events_list.head);
 235         channel->event_count++;
 236
 237         DBG("Event %s created (fd: %d)", ev->name, event->fd);
 238
 239         return 0;
 240
 241 free_event:
 242         free(event);
 243 error:
 244         return ret;
 245 }
 246
 247 /*
 248  * Disable a kernel channel.
 249  */
 250 int kernel_disable_channel(struct ltt_kernel_channel *chan)
 251 {
 252         int ret;
 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         ret = kernctl_enable(chan->fd);
 278         if (ret < 0 && errno != EEXIST) {
 279                 PERROR("Enable kernel chan");
 280                 goto error;
 281         }
 282
 283         chan->enabled = 1;
 284         DBG("Kernel channel %s enabled (fd: %d)", chan->channel->name, chan->fd);
 285
 286         return 0;
 287
 288 error:
 289         return ret;
 290 }
 291
 292 /*
 293  * Enable a kernel event.
 294  */
 295 int kernel_enable_event(struct ltt_kernel_event *event)
 296 {
 297         int ret;
 298
 299         ret = kernctl_enable(event->fd);
 300         if (ret < 0) {
 301                 switch (errno) {
 302                 case EEXIST:
 303                         ret = LTTCOMM_KERN_EVENT_EXIST;
 304                         break;
 305                 default:
 306                         PERROR("enable kernel event");
 307                         break;
 308                 }
 309                 goto error;
 310         }
 311
 312         event->enabled = 1;
 313         DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
 314
 315         return 0;
 316
 317 error:
 318         return ret;
 319 }
 320
 321 /*
 322  * Disable a kernel event.
 323  */
 324 int kernel_disable_event(struct ltt_kernel_event *event)
 325 {
 326         int ret;
 327
 328         ret = kernctl_disable(event->fd);
 329         if (ret < 0) {
 330                 switch (errno) {
 331                 case EEXIST:
 332                         ret = LTTCOMM_KERN_EVENT_EXIST;
 333                         break;
 334                 default:
 335                         PERROR("disable kernel event");
 336                         break;
 337                 }
 338                 goto error;
 339         }
 340
 341         event->enabled = 0;
 342         DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
 343
 344         return 0;
 345
 346 error:
 347         return ret;
 348 }
 349
 350 /*
 351  * Create kernel metadata, open from the kernel tracer and add it to the
 352  * kernel session.
 353  */
 354 int kernel_open_metadata(struct ltt_kernel_session *session, char *path)
 355 {
 356         int ret;
 357         struct ltt_kernel_metadata *lkm;
 358
 359         /* Allocate kernel metadata */
 360         lkm = trace_kernel_create_metadata(path);
 361         if (lkm == NULL) {
 362                 goto error;
 363         }
 364
 365         /* Kernel tracer metadata creation */
 366         ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
 367         if (ret < 0) {
 368                 goto error;
 369         }
 370
 371         lkm->fd = ret;
 372         /* Prevent fd duplication after execlp() */
 373         ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
 374         if (ret < 0) {
 375                 PERROR("fcntl session fd");
 376         }
 377
 378         session->metadata = lkm;
 379
 380         DBG("Kernel metadata opened (fd: %d and path: %s)", lkm->fd, lkm->pathname);
 381
 382         return 0;
 383
 384 error:
 385         return -1;
 386 }
 387
 388 /*
 389  * Start tracing session.
 390  */
 391 int kernel_start_session(struct ltt_kernel_session *session)
 392 {
 393         int ret;
 394
 395         ret = kernctl_start_session(session->fd);
 396         if (ret < 0) {
 397                 PERROR("ioctl start session");
 398                 goto error;
 399         }
 400
 401         DBG("Kernel session started");
 402
 403         return 0;
 404
 405 error:
 406         return ret;
 407 }
 408
 409 /*
 410  * Make a kernel wait to make sure in-flight probe have completed.
 411  */
 412 void kernel_wait_quiescent(int fd)
 413 {
 414         int ret;
 415
 416         DBG("Kernel quiescent wait on %d", fd);
 417
 418         ret = kernctl_wait_quiescent(fd);
 419         if (ret < 0) {
 420                 PERROR("wait quiescent ioctl");
 421                 ERR("Kernel quiescent wait failed");
 422         }
 423 }
 424
 425 /*
 426  * Kernel calibrate
 427  */
 428 int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
 429 {
 430         int ret;
 431
 432         ret = kernctl_calibrate(fd, calibrate);
 433         if (ret < 0) {
 434                 PERROR("calibrate ioctl");
 435                 return -1;
 436         }
 437
 438         return 0;
 439 }
 440
 441
 442 /*
 443  *  Force flush buffer of metadata.
 444  */
 445 int kernel_metadata_flush_buffer(int fd)
 446 {
 447         int ret;
 448
 449         ret = kernctl_buffer_flush(fd);
 450         if (ret < 0) {
 451                 ERR("Fail to flush metadata buffers %d (ret: %d", fd, ret);
 452         }
 453
 454         return 0;
 455 }
 456
 457 /*
 458  * Force flush buffer for channel.
 459  */
 460 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
 461 {
 462         int ret;
 463         struct ltt_kernel_stream *stream;
 464
 465         DBG("Flush buffer for channel %s", channel->channel->name);
 466
 467         cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
 468                 DBG("Flushing channel stream %d", stream->fd);
 469                 ret = kernctl_buffer_flush(stream->fd);
 470                 if (ret < 0) {
 471                         PERROR("ioctl");
 472                         ERR("Fail to flush buffer for stream %d (ret: %d)",
 473                                         stream->fd, ret);
 474                 }
 475         }
 476
 477         return 0;
 478 }
 479
 480 /*
 481  * Stop tracing session.
 482  */
 483 int kernel_stop_session(struct ltt_kernel_session *session)
 484 {
 485         int ret;
 486
 487         ret = kernctl_stop_session(session->fd);
 488         if (ret < 0) {
 489                 goto error;
 490         }
 491
 492         DBG("Kernel session stopped");
 493
 494         return 0;
 495
 496 error:
 497         return ret;
 498 }
 499
 500 /*
 501  * Open stream of channel, register it to the kernel tracer and add it
 502  * to the stream list of the channel.
 503  *
 504  * Return the number of created stream. Else, a negative value.
 505  */
 506 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 507 {
 508         int ret;
 509         struct ltt_kernel_stream *lks;
 510
 511         while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
 512                 lks = trace_kernel_create_stream();
 513                 if (lks == NULL) {
 514                         ret = close(ret);
 515                         if (ret) {
 516                                 PERROR("close");
 517                         }
 518                         goto error;
 519                 }
 520
 521                 lks->fd = ret;
 522                 /* Prevent fd duplication after execlp() */
 523                 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 524                 if (ret < 0) {
 525                         PERROR("fcntl session fd");
 526                 }
 527
 528                 ret = asprintf(&lks->pathname, "%s/%s_%d",
 529                                 channel->pathname, channel->channel->name, channel->stream_count);
 530                 if (ret < 0) {
 531                         PERROR("asprintf kernel create stream");
 532                         goto error;
 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                 DBG("Kernel stream %d created (fd: %d, state: %d, path: %s)",
 540                                 channel->stream_count, lks->fd, lks->state, lks->pathname);
 541         }
 542
 543         return channel->stream_count;
 544
 545 error:
 546         return -1;
 547 }
 548
 549 /*
 550  * Open the metadata stream and set it to the kernel session.
 551  */
 552 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
 553 {
 554         int ret;
 555
 556         ret = kernctl_create_stream(session->metadata->fd);
 557         if (ret < 0) {
 558                 PERROR("kernel create metadata stream");
 559                 goto error;
 560         }
 561
 562         DBG("Kernel metadata stream created (fd: %d)", ret);
 563         session->metadata_stream_fd = ret;
 564         /* Prevent fd duplication after execlp() */
 565         ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
 566         if (ret < 0) {
 567                 PERROR("fcntl session fd");
 568         }
 569
 570         return 0;
 571
 572 error:
 573         return -1;
 574 }
 575
 576 /*
 577  * Get the event list from the kernel tracer and return the number of elements.
 578  */
 579 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 580 {
 581         int fd, pos, ret;
 582         char *event;
 583         size_t nbmem, count = 0;
 584         ssize_t size;
 585         FILE *fp;
 586         struct lttng_event *elist;
 587
 588         fd = kernctl_tracepoint_list(tracer_fd);
 589         if (fd < 0) {
 590                 PERROR("kernel tracepoint list");
 591                 goto error;
 592         }
 593
 594         fp = fdopen(fd, "r");
 595         if (fp == NULL) {
 596                 PERROR("kernel tracepoint list fdopen");
 597                 goto error_fp;
 598         }
 599
 600         /*
 601          * Init memory size counter
 602          * See kernel-ctl.h for explanation of this value
 603          */
 604         nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
 605         elist = zmalloc(sizeof(struct lttng_event) * nbmem);
 606         if (elist == NULL) {
 607                 PERROR("alloc list events");
 608                 count = -ENOMEM;
 609                 goto end;
 610         }
 611
 612         while ((size = fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos)) == 1) {
 613                 if (count >= nbmem) {
 614                         struct lttng_event *new_elist;
 615
 616                         DBG("Reallocating event list from %zu to %zu bytes", nbmem,
 617                                         nbmem * 2);
 618                         /* Double the size */
 619                         nbmem <<= 1;
 620                         new_elist = realloc(elist, nbmem * sizeof(struct lttng_event));
 621                         if (new_elist == NULL) {
 622                                 PERROR("realloc list events");
 623                                 free(event);
 624                                 free(elist);
 625                                 count = -ENOMEM;
 626                                 goto end;
 627                         }
 628                         elist = new_elist;
 629                 }
 630                 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
 631                 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 632                 elist[count].enabled = -1;
 633                 count++;
 634                 free(event);
 635         }
 636
 637         *events = elist;
 638         DBG("Kernel list events done (%zu events)", count);
 639 end:
 640         ret = fclose(fp);       /* closes both fp and fd */
 641         if (ret) {
 642                 PERROR("fclose");
 643         }
 644         return count;
 645
 646 error_fp:
 647         ret = close(fd);
 648         if (ret) {
 649                 PERROR("close");
 650         }
 651 error:
 652         return -1;
 653 }
 654
 655 /*
 656  * Get kernel version and validate it.
 657  */
 658 int kernel_validate_version(int tracer_fd)
 659 {
 660         int ret;
 661         struct lttng_kernel_tracer_version version;
 662
 663         ret = kernctl_tracer_version(tracer_fd, &version);
 664         if (ret < 0) {
 665                 ERR("Failed at getting the lttng-modules version");
 666                 goto error;
 667         }
 668
 669         /* Validate version */
 670         if (version.major != KERN_MODULES_PRE_MAJOR
 671                 && version.major != KERN_MODULES_MAJOR) {
 672                 goto error_version;
 673         }
 674
 675         DBG2("Kernel tracer version validated (major version %d)", version.major);
 676         return 0;
 677
 678 error_version:
 679         ERR("Kernel major version %d is not compatible (supporting <= %d)",
 680                         version.major, KERN_MODULES_MAJOR)
 681         ret = -1;
 682
 683 error:
 684         return ret;
 685 }
 686
 687 /*
 688  * Kernel work-arounds called at the start of sessiond main().
 689  */
 690 int init_kernel_workarounds(void)
 691 {
 692         int ret;
 693         FILE *fp;
 694
 695         /*
 696          * boot_id needs to be read once before being used concurrently
 697          * to deal with a Linux kernel race. A fix is proposed for
 698          * upstream, but the work-around is needed for older kernels.
 699          */
 700         fp = fopen("/proc/sys/kernel/random/boot_id", "r");
 701         if (!fp) {
 702                 goto end_boot_id;
 703         }
 704         while (!feof(fp)) {
 705                 char buf[37] = "";
 706
 707                 ret = fread(buf, 1, sizeof(buf), fp);
 708                 if (ret < 0) {
 709                         /* Ignore error, we don't really care */
 710                 }
 711         }
 712         ret = fclose(fp);
 713         if (ret) {
 714                 PERROR("fclose");
 715         }
 716 end_boot_id:
 717         return 0;
 718 }