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 "kernel.h"
  32 #include "kern-modules.h"
  33
  34 /*
  35  * Add context on a kernel channel.
  36  */
  37 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
  38                 struct lttng_kernel_context *ctx)
  39 {
  40         int ret;
  41
  42         DBG("Adding context to channel %s", chan->channel->name);
  43         ret = kernctl_add_context(chan->fd, ctx);
  44         if (ret < 0) {
  45                 if (errno != EEXIST) {
  46                         PERROR("add context ioctl");
  47                 } else {
  48                         /* If EEXIST, we just ignore the error */
  49                         ret = 0;
  50                 }
  51                 goto error;
  52         }
  53
  54         chan->ctx = zmalloc(sizeof(struct lttng_kernel_context));
  55         if (chan->ctx == NULL) {
  56                 PERROR("zmalloc event context");
  57                 goto error;
  58         }
  59
  60         memcpy(chan->ctx, ctx, sizeof(struct lttng_kernel_context));
  61
  62         return 0;
  63
  64 error:
  65         return ret;
  66 }
  67
  68 /*
  69  * Add context on a kernel event.
  70  */
  71 int kernel_add_event_context(struct ltt_kernel_event *event,
  72                 struct lttng_kernel_context *ctx)
  73 {
  74         int ret;
  75
  76         DBG("Adding context to event %s", event->event->name);
  77         ret = kernctl_add_context(event->fd, ctx);
  78         if (ret < 0) {
  79                 PERROR("add context ioctl");
  80                 goto error;
  81         }
  82
  83         event->ctx = zmalloc(sizeof(struct lttng_kernel_context));
  84         if (event->ctx == NULL) {
  85                 PERROR("zmalloc event context");
  86                 goto error;
  87         }
  88
  89         memcpy(event->ctx, ctx, sizeof(struct lttng_kernel_context));
  90
  91         return 0;
  92
  93 error:
  94         return ret;
  95 }
  96
  97 /*
  98  * Create a new kernel session, register it to the kernel tracer and add it to
  99  * the session daemon session.
 100  */
 101 int kernel_create_session(struct ltt_session *session, int tracer_fd)
 102 {
 103         int ret;
 104         struct ltt_kernel_session *lks;
 105
 106         /* Allocate data structure */
 107         lks = trace_kernel_create_session(session->path);
 108         if (lks == NULL) {
 109                 ret = -1;
 110                 goto error;
 111         }
 112
 113         /* Kernel tracer session creation */
 114         ret = kernctl_create_session(tracer_fd);
 115         if (ret < 0) {
 116                 PERROR("ioctl kernel create session");
 117                 goto error;
 118         }
 119
 120         lks->fd = ret;
 121         /* Prevent fd duplication after execlp() */
 122         ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 123         if (ret < 0) {
 124                 PERROR("fcntl session fd");
 125         }
 126
 127         lks->consumer_fds_sent = 0;
 128         session->kernel_session = lks;
 129
 130         DBG("Kernel session created (fd: %d)", lks->fd);
 131
 132         return 0;
 133
 134 error:
 135         return ret;
 136 }
 137
 138 /*
 139  * Create a kernel channel, register it to the kernel tracer and add it to the
 140  * kernel session.
 141  */
 142 int kernel_create_channel(struct ltt_kernel_session *session,
 143                 struct lttng_channel *chan, char *path)
 144 {
 145         int ret;
 146         struct ltt_kernel_channel *lkc;
 147
 148         /* Allocate kernel channel */
 149         lkc = trace_kernel_create_channel(chan, path);
 150         if (lkc == NULL) {
 151                 goto error;
 152         }
 153
 154         DBG3("Kernel create channel %s in %s with attr: %d, %" PRIu64 ", %" PRIu64 ", %u, %u, %d",
 155                         chan->name, path, lkc->channel->attr.overwrite,
 156                         lkc->channel->attr.subbuf_size, lkc->channel->attr.num_subbuf,
 157                         lkc->channel->attr.switch_timer_interval, lkc->channel->attr.read_timer_interval,
 158                         lkc->channel->attr.output);
 159
 160         /* Kernel tracer channel creation */
 161         ret = kernctl_create_channel(session->fd, &lkc->channel->attr);
 162         if (ret < 0) {
 163                 PERROR("ioctl kernel create channel");
 164                 goto error;
 165         }
 166
 167         /* Setup the channel fd */
 168         lkc->fd = ret;
 169         /* Prevent fd duplication after execlp() */
 170         ret = fcntl(lkc->fd, F_SETFD, FD_CLOEXEC);
 171         if (ret < 0) {
 172                 PERROR("fcntl session fd");
 173         }
 174
 175         /* Add channel to session */
 176         cds_list_add(&lkc->list, &session->channel_list.head);
 177         session->channel_count++;
 178
 179         DBG("Kernel channel %s created (fd: %d)", lkc->channel->name, lkc->fd);
 180
 181         return 0;
 182
 183 error:
 184         return -1;
 185 }
 186
 187 /*
 188  * Create a kernel event, enable it to the kernel tracer and add it to the
 189  * channel event list of the kernel session.
 190  */
 191 int kernel_create_event(struct lttng_event *ev,
 192                 struct ltt_kernel_channel *channel)
 193 {
 194         int ret;
 195         struct ltt_kernel_event *event;
 196
 197         event = trace_kernel_create_event(ev);
 198         if (event == NULL) {
 199                 ret = -1;
 200                 goto error;
 201         }
 202
 203         ret = kernctl_create_event(channel->fd, event->event);
 204         if (ret < 0) {
 205                 switch (errno) {
 206                 case EEXIST:
 207                         break;
 208                 case ENOSYS:
 209                         WARN("Event type not implemented");
 210                         break;
 211                 default:
 212                         PERROR("create event ioctl");
 213                 }
 214                 ret = -errno;
 215                 goto free_event;
 216         }
 217
 218         /*
 219          * LTTNG_KERNEL_SYSCALL event creation will return 0 on success.
 220          */
 221         if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
 222                 DBG2("Kernel event syscall creation success");
 223                 /*
 224                  * We use fd == -1 to ensure that we never trigger a close of fd
 225                  * 0.
 226                  */
 227                 event->fd = -1;
 228                 goto add_list;
 229         }
 230
 231         event->fd = ret;
 232         /* Prevent fd duplication after execlp() */
 233         ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
 234         if (ret < 0) {
 235                 PERROR("fcntl session fd");
 236         }
 237
 238 add_list:
 239         /* Add event to event list */
 240         cds_list_add(&event->list, &channel->events_list.head);
 241         channel->event_count++;
 242
 243         DBG("Event %s created (fd: %d)", ev->name, event->fd);
 244
 245         return 0;
 246
 247 free_event:
 248         free(event);
 249 error:
 250         return ret;
 251 }
 252
 253 /*
 254  * Disable a kernel channel.
 255  */
 256 int kernel_disable_channel(struct ltt_kernel_channel *chan)
 257 {
 258         int ret;
 259
 260         ret = kernctl_disable(chan->fd);
 261         if (ret < 0) {
 262                 PERROR("disable chan ioctl");
 263                 ret = errno;
 264                 goto error;
 265         }
 266
 267         chan->enabled = 0;
 268         DBG("Kernel channel %s disabled (fd: %d)", chan->channel->name, chan->fd);
 269
 270         return 0;
 271
 272 error:
 273         return ret;
 274 }
 275
 276 /*
 277  * Enable a kernel channel.
 278  */
 279 int kernel_enable_channel(struct ltt_kernel_channel *chan)
 280 {
 281         int ret;
 282
 283         ret = kernctl_enable(chan->fd);
 284         if (ret < 0 && errno != EEXIST) {
 285                 PERROR("Enable kernel chan");
 286                 goto error;
 287         }
 288
 289         chan->enabled = 1;
 290         DBG("Kernel channel %s enabled (fd: %d)", chan->channel->name, chan->fd);
 291
 292         return 0;
 293
 294 error:
 295         return ret;
 296 }
 297
 298 /*
 299  * Enable a kernel event.
 300  */
 301 int kernel_enable_event(struct ltt_kernel_event *event)
 302 {
 303         int ret;
 304
 305         ret = kernctl_enable(event->fd);
 306         if (ret < 0) {
 307                 switch (errno) {
 308                 case EEXIST:
 309                         ret = LTTCOMM_KERN_EVENT_EXIST;
 310                         break;
 311                 default:
 312                         PERROR("enable kernel event");
 313                         break;
 314                 }
 315                 goto error;
 316         }
 317
 318         event->enabled = 1;
 319         DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
 320
 321         return 0;
 322
 323 error:
 324         return ret;
 325 }
 326
 327 /*
 328  * Disable a kernel event.
 329  */
 330 int kernel_disable_event(struct ltt_kernel_event *event)
 331 {
 332         int ret;
 333
 334         ret = kernctl_disable(event->fd);
 335         if (ret < 0) {
 336                 switch (errno) {
 337                 case EEXIST:
 338                         ret = LTTCOMM_KERN_EVENT_EXIST;
 339                         break;
 340                 default:
 341                         PERROR("disable kernel event");
 342                         break;
 343                 }
 344                 goto error;
 345         }
 346
 347         event->enabled = 0;
 348         DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
 349
 350         return 0;
 351
 352 error:
 353         return ret;
 354 }
 355
 356 /*
 357  * Create kernel metadata, open from the kernel tracer and add it to the
 358  * kernel session.
 359  */
 360 int kernel_open_metadata(struct ltt_kernel_session *session)
 361 {
 362         int ret;
 363         struct ltt_kernel_metadata *lkm;
 364
 365         /* Allocate kernel metadata */
 366         lkm = trace_kernel_create_metadata();
 367         if (lkm == NULL) {
 368                 goto error;
 369         }
 370
 371         /* Kernel tracer metadata creation */
 372         ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
 373         if (ret < 0) {
 374                 goto error;
 375         }
 376
 377         lkm->fd = ret;
 378         /* Prevent fd duplication after execlp() */
 379         ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
 380         if (ret < 0) {
 381                 PERROR("fcntl session fd");
 382         }
 383
 384         session->metadata = lkm;
 385
 386         DBG("Kernel metadata opened (fd: %d)", lkm->fd);
 387
 388         return 0;
 389
 390 error:
 391         return -1;
 392 }
 393
 394 /*
 395  * Start tracing session.
 396  */
 397 int kernel_start_session(struct ltt_kernel_session *session)
 398 {
 399         int ret;
 400
 401         ret = kernctl_start_session(session->fd);
 402         if (ret < 0) {
 403                 PERROR("ioctl start session");
 404                 goto error;
 405         }
 406
 407         DBG("Kernel session started");
 408
 409         return 0;
 410
 411 error:
 412         return ret;
 413 }
 414
 415 /*
 416  * Make a kernel wait to make sure in-flight probe have completed.
 417  */
 418 void kernel_wait_quiescent(int fd)
 419 {
 420         int ret;
 421
 422         DBG("Kernel quiescent wait on %d", fd);
 423
 424         ret = kernctl_wait_quiescent(fd);
 425         if (ret < 0) {
 426                 PERROR("wait quiescent ioctl");
 427                 ERR("Kernel quiescent wait failed");
 428         }
 429 }
 430
 431 /*
 432  * Kernel calibrate
 433  */
 434 int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
 435 {
 436         int ret;
 437
 438         ret = kernctl_calibrate(fd, calibrate);
 439         if (ret < 0) {
 440                 PERROR("calibrate ioctl");
 441                 return -1;
 442         }
 443
 444         return 0;
 445 }
 446
 447
 448 /*
 449  *  Force flush buffer of metadata.
 450  */
 451 int kernel_metadata_flush_buffer(int fd)
 452 {
 453         int ret;
 454
 455         ret = kernctl_buffer_flush(fd);
 456         if (ret < 0) {
 457                 ERR("Fail to flush metadata buffers %d (ret: %d)", fd, ret);
 458         }
 459
 460         return 0;
 461 }
 462
 463 /*
 464  * Force flush buffer for channel.
 465  */
 466 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
 467 {
 468         int ret;
 469         struct ltt_kernel_stream *stream;
 470
 471         DBG("Flush buffer for channel %s", channel->channel->name);
 472
 473         cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
 474                 DBG("Flushing channel stream %d", stream->fd);
 475                 ret = kernctl_buffer_flush(stream->fd);
 476                 if (ret < 0) {
 477                         PERROR("ioctl");
 478                         ERR("Fail to flush buffer for stream %d (ret: %d)",
 479                                         stream->fd, ret);
 480                 }
 481         }
 482
 483         return 0;
 484 }
 485
 486 /*
 487  * Stop tracing session.
 488  */
 489 int kernel_stop_session(struct ltt_kernel_session *session)
 490 {
 491         int ret;
 492
 493         ret = kernctl_stop_session(session->fd);
 494         if (ret < 0) {
 495                 goto error;
 496         }
 497
 498         DBG("Kernel session stopped");
 499
 500         return 0;
 501
 502 error:
 503         return ret;
 504 }
 505
 506 /*
 507  * Open stream of channel, register it to the kernel tracer and add it
 508  * to the stream list of the channel.
 509  *
 510  * Return the number of created stream. Else, a negative value.
 511  */
 512 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 513 {
 514         int ret, count = 0;
 515         struct ltt_kernel_stream *lks;
 516
 517         while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
 518                 lks = trace_kernel_create_stream(channel->channel->name, count);
 519                 if (lks == NULL) {
 520                         ret = close(ret);
 521                         if (ret) {
 522                                 PERROR("close");
 523                         }
 524                         goto error;
 525                 }
 526
 527                 lks->fd = ret;
 528                 /* Prevent fd duplication after execlp() */
 529                 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 530                 if (ret < 0) {
 531                         PERROR("fcntl session fd");
 532                 }
 533
 534                 /* Add stream to channe stream list */
 535                 cds_list_add(&lks->list, &channel->stream_list.head);
 536                 channel->stream_count++;
 537
 538                 /* Increment counter which represent CPU number. */
 539                 count++;
 540
 541                 DBG("Kernel stream %s created (fd: %d, state: %d)", lks->name, lks->fd,
 542                                 lks->state);
 543         }
 544
 545         return channel->stream_count;
 546
 547 error:
 548         return -1;
 549 }
 550
 551 /*
 552  * Open the metadata stream and set it to the kernel session.
 553  */
 554 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
 555 {
 556         int ret;
 557
 558         ret = kernctl_create_stream(session->metadata->fd);
 559         if (ret < 0) {
 560                 PERROR("kernel create metadata stream");
 561                 goto error;
 562         }
 563
 564         DBG("Kernel metadata stream created (fd: %d)", ret);
 565         session->metadata_stream_fd = ret;
 566         /* Prevent fd duplication after execlp() */
 567         ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
 568         if (ret < 0) {
 569                 PERROR("fcntl session fd");
 570         }
 571
 572         return 0;
 573
 574 error:
 575         return -1;
 576 }
 577
 578 /*
 579  * Get the event list from the kernel tracer and return the number of elements.
 580  */
 581 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 582 {
 583         int fd, pos, ret;
 584         char *event;
 585         size_t nbmem, count = 0;
 586         ssize_t size;
 587         FILE *fp;
 588         struct lttng_event *elist;
 589
 590         fd = kernctl_tracepoint_list(tracer_fd);
 591         if (fd < 0) {
 592                 PERROR("kernel tracepoint list");
 593                 goto error;
 594         }
 595
 596         fp = fdopen(fd, "r");
 597         if (fp == NULL) {
 598                 PERROR("kernel tracepoint list fdopen");
 599                 goto error_fp;
 600         }
 601
 602         /*
 603          * Init memory size counter
 604          * See kernel-ctl.h for explanation of this value
 605          */
 606         nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
 607         elist = zmalloc(sizeof(struct lttng_event) * nbmem);
 608         if (elist == NULL) {
 609                 PERROR("alloc list events");
 610                 count = -ENOMEM;
 611                 goto end;
 612         }
 613
 614         while ((size = fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos)) == 1) {
 615                 if (count >= nbmem) {
 616                         struct lttng_event *new_elist;
 617
 618                         DBG("Reallocating event list from %zu to %zu bytes", nbmem,
 619                                         nbmem * 2);
 620                         /* Double the size */
 621                         nbmem <<= 1;
 622                         new_elist = realloc(elist, nbmem * sizeof(struct lttng_event));
 623                         if (new_elist == NULL) {
 624                                 PERROR("realloc list events");
 625                                 free(event);
 626                                 free(elist);
 627                                 count = -ENOMEM;
 628                                 goto end;
 629                         }
 630                         elist = new_elist;
 631                 }
 632                 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
 633                 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 634                 elist[count].enabled = -1;
 635                 count++;
 636                 free(event);
 637         }
 638
 639         *events = elist;
 640         DBG("Kernel list events done (%zu events)", count);
 641 end:
 642         ret = fclose(fp);       /* closes both fp and fd */
 643         if (ret) {
 644                 PERROR("fclose");
 645         }
 646         return count;
 647
 648 error_fp:
 649         ret = close(fd);
 650         if (ret) {
 651                 PERROR("close");
 652         }
 653 error:
 654         return -1;
 655 }
 656
 657 /*
 658  * Get kernel version and validate it.
 659  */
 660 int kernel_validate_version(int tracer_fd)
 661 {
 662         int ret;
 663         struct lttng_kernel_tracer_version version;
 664
 665         ret = kernctl_tracer_version(tracer_fd, &version);
 666         if (ret < 0) {
 667                 ERR("Failed at getting the lttng-modules version");
 668                 goto error;
 669         }
 670
 671         /* Validate version */
 672         if (version.major != KERN_MODULES_PRE_MAJOR
 673                 && version.major != KERN_MODULES_MAJOR) {
 674                 goto error_version;
 675         }
 676
 677         DBG2("Kernel tracer version validated (major version %d)", version.major);
 678         return 0;
 679
 680 error_version:
 681         ERR("Kernel major version %d is not compatible (supporting <= %d)",
 682                         version.major, KERN_MODULES_MAJOR)
 683         ret = -1;
 684
 685 error:
 686         return ret;
 687 }
 688
 689 /*
 690  * Kernel work-arounds called at the start of sessiond main().
 691  */
 692 int init_kernel_workarounds(void)
 693 {
 694         int ret;
 695         FILE *fp;
 696
 697         /*
 698          * boot_id needs to be read once before being used concurrently
 699          * to deal with a Linux kernel race. A fix is proposed for
 700          * upstream, but the work-around is needed for older kernels.
 701          */
 702         fp = fopen("/proc/sys/kernel/random/boot_id", "r");
 703         if (!fp) {
 704                 goto end_boot_id;
 705         }
 706         while (!feof(fp)) {
 707                 char buf[37] = "";
 708
 709                 ret = fread(buf, 1, sizeof(buf), fp);
 710                 if (ret < 0) {
 711                         /* Ignore error, we don't really care */
 712                 }
 713         }
 714         ret = fclose(fp);
 715         if (ret) {
 716                 PERROR("fclose");
 717         }
 718 end_boot_id:
 719         return 0;
 720 }