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
  29 #include "kernel.h"
  30 #include "kern-modules.h"
  31
  32 /*
  33  * Add context on a kernel channel.
  34  */
  35 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
  36                 struct lttng_kernel_context *ctx)
  37 {
  38         int ret;
  39
  40         DBG("Adding context to channel %s", chan->channel->name);
  41         ret = kernctl_add_context(chan->fd, ctx);
  42         if (ret < 0) {
  43                 if (errno != EEXIST) {
  44                         PERROR("add context ioctl");
  45                 } else {
  46                         /* If EEXIST, we just ignore the error */
  47                         ret = 0;
  48                 }
  49                 goto error;
  50         }
  51
  52         chan->ctx = zmalloc(sizeof(struct lttng_kernel_context));
  53         if (chan->ctx == NULL) {
  54                 PERROR("zmalloc event context");
  55                 goto error;
  56         }
  57
  58         memcpy(chan->ctx, ctx, sizeof(struct lttng_kernel_context));
  59
  60         return 0;
  61
  62 error:
  63         return ret;
  64 }
  65
  66 /*
  67  * Add context on a kernel event.
  68  */
  69 int kernel_add_event_context(struct ltt_kernel_event *event,
  70                 struct lttng_kernel_context *ctx)
  71 {
  72         int ret;
  73
  74         DBG("Adding context to event %s", event->event->name);
  75         ret = kernctl_add_context(event->fd, ctx);
  76         if (ret < 0) {
  77                 PERROR("add context ioctl");
  78                 goto error;
  79         }
  80
  81         event->ctx = zmalloc(sizeof(struct lttng_kernel_context));
  82         if (event->ctx == NULL) {
  83                 PERROR("zmalloc event context");
  84                 goto error;
  85         }
  86
  87         memcpy(event->ctx, ctx, sizeof(struct lttng_kernel_context));
  88
  89         return 0;
  90
  91 error:
  92         return ret;
  93 }
  94
  95 /*
  96  * Create a new kernel session, register it to the kernel tracer and add it to
  97  * the session daemon session.
  98  */
  99 int kernel_create_session(struct ltt_session *session, int tracer_fd)
 100 {
 101         int ret;
 102         struct ltt_kernel_session *lks;
 103
 104         /* Allocate data structure */
 105         lks = trace_kernel_create_session(session->path);
 106         if (lks == NULL) {
 107                 ret = -1;
 108                 goto error;
 109         }
 110
 111         /* Kernel tracer session creation */
 112         ret = kernctl_create_session(tracer_fd);
 113         if (ret < 0) {
 114                 PERROR("ioctl kernel create session");
 115                 goto error;
 116         }
 117
 118         lks->fd = ret;
 119         /* Prevent fd duplication after execlp() */
 120         ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 121         if (ret < 0) {
 122                 PERROR("fcntl session fd");
 123         }
 124
 125         lks->consumer_fds_sent = 0;
 126         session->kernel_session = lks;
 127
 128         DBG("Kernel session created (fd: %d)", lks->fd);
 129
 130         return 0;
 131
 132 error:
 133         return ret;
 134 }
 135
 136 /*
 137  * Create a kernel channel, register it to the kernel tracer and add it to the
 138  * kernel session.
 139  */
 140 int kernel_create_channel(struct ltt_kernel_session *session,
 141                 struct lttng_channel *chan, char *path)
 142 {
 143         int ret;
 144         struct ltt_kernel_channel *lkc;
 145
 146         /* Allocate kernel channel */
 147         lkc = trace_kernel_create_channel(chan, path);
 148         if (lkc == NULL) {
 149                 goto error;
 150         }
 151
 152         /* Kernel tracer channel creation */
 153         ret = kernctl_create_channel(session->fd, &lkc->channel->attr);
 154         if (ret < 0) {
 155                 PERROR("ioctl kernel create channel");
 156                 goto error;
 157         }
 158
 159         /* Setup the channel fd */
 160         lkc->fd = ret;
 161         /* Prevent fd duplication after execlp() */
 162         ret = fcntl(lkc->fd, F_SETFD, FD_CLOEXEC);
 163         if (ret < 0) {
 164                 PERROR("fcntl session fd");
 165         }
 166
 167         /* Add channel to session */
 168         cds_list_add(&lkc->list, &session->channel_list.head);
 169         session->channel_count++;
 170
 171         DBG("Kernel channel %s created (fd: %d and path: %s)",
 172                         lkc->channel->name, lkc->fd, lkc->pathname);
 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                 if (errno != EEXIST) {
 199                         PERROR("create event ioctl");
 200                 }
 201                 ret = -errno;
 202                 goto free_event;
 203         }
 204
 205         /*
 206          * LTTNG_KERNEL_SYSCALL event creation will return 0 on success.
 207          */
 208         if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
 209                 DBG2("Kernel event syscall creation success");
 210                 /*
 211                  * We use fd == -1 to ensure that we never trigger a close of fd
 212                  * 0.
 213                  */
 214                 event->fd = -1;
 215                 goto add_list;
 216         }
 217
 218         event->fd = ret;
 219         /* Prevent fd duplication after execlp() */
 220         ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
 221         if (ret < 0) {
 222                 PERROR("fcntl session fd");
 223         }
 224
 225 add_list:
 226         /* Add event to event list */
 227         cds_list_add(&event->list, &channel->events_list.head);
 228         channel->event_count++;
 229
 230         DBG("Event %s created (fd: %d)", ev->name, event->fd);
 231
 232         return 0;
 233
 234 free_event:
 235         free(event);
 236 error:
 237         return ret;
 238 }
 239
 240 /*
 241  * Disable a kernel channel.
 242  */
 243 int kernel_disable_channel(struct ltt_kernel_channel *chan)
 244 {
 245         int ret;
 246
 247         ret = kernctl_disable(chan->fd);
 248         if (ret < 0) {
 249                 PERROR("disable chan ioctl");
 250                 ret = errno;
 251                 goto error;
 252         }
 253
 254         chan->enabled = 0;
 255         DBG("Kernel channel %s disabled (fd: %d)", chan->channel->name, chan->fd);
 256
 257         return 0;
 258
 259 error:
 260         return ret;
 261 }
 262
 263 /*
 264  * Enable a kernel channel.
 265  */
 266 int kernel_enable_channel(struct ltt_kernel_channel *chan)
 267 {
 268         int ret;
 269
 270         ret = kernctl_enable(chan->fd);
 271         if (ret < 0 && errno != EEXIST) {
 272                 PERROR("Enable kernel chan");
 273                 goto error;
 274         }
 275
 276         chan->enabled = 1;
 277         DBG("Kernel channel %s enabled (fd: %d)", chan->channel->name, chan->fd);
 278
 279         return 0;
 280
 281 error:
 282         return ret;
 283 }
 284
 285 /*
 286  * Enable a kernel event.
 287  */
 288 int kernel_enable_event(struct ltt_kernel_event *event)
 289 {
 290         int ret;
 291
 292         ret = kernctl_enable(event->fd);
 293         if (ret < 0 && errno != EEXIST) {
 294                 PERROR("enable kernel event");
 295                 goto error;
 296         }
 297
 298         event->enabled = 1;
 299         DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
 300
 301         return 0;
 302
 303 error:
 304         return ret;
 305 }
 306
 307 /*
 308  * Disable a kernel event.
 309  */
 310 int kernel_disable_event(struct ltt_kernel_event *event)
 311 {
 312         int ret;
 313
 314         ret = kernctl_disable(event->fd);
 315         if (ret < 0 && errno != EEXIST) {
 316                 PERROR("disable kernel event");
 317                 goto error;
 318         }
 319
 320         event->enabled = 0;
 321         DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
 322
 323         return 0;
 324
 325 error:
 326         return ret;
 327 }
 328
 329 /*
 330  * Create kernel metadata, open from the kernel tracer and add it to the
 331  * kernel session.
 332  */
 333 int kernel_open_metadata(struct ltt_kernel_session *session, char *path)
 334 {
 335         int ret;
 336         struct ltt_kernel_metadata *lkm;
 337
 338         /* Allocate kernel metadata */
 339         lkm = trace_kernel_create_metadata(path);
 340         if (lkm == NULL) {
 341                 goto error;
 342         }
 343
 344         /* Kernel tracer metadata creation */
 345         ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
 346         if (ret < 0) {
 347                 goto error;
 348         }
 349
 350         lkm->fd = ret;
 351         /* Prevent fd duplication after execlp() */
 352         ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
 353         if (ret < 0) {
 354                 PERROR("fcntl session fd");
 355         }
 356
 357         session->metadata = lkm;
 358
 359         DBG("Kernel metadata opened (fd: %d and path: %s)", lkm->fd, lkm->pathname);
 360
 361         return 0;
 362
 363 error:
 364         return -1;
 365 }
 366
 367 /*
 368  * Start tracing session.
 369  */
 370 int kernel_start_session(struct ltt_kernel_session *session)
 371 {
 372         int ret;
 373
 374         ret = kernctl_start_session(session->fd);
 375         if (ret < 0) {
 376                 PERROR("ioctl start session");
 377                 goto error;
 378         }
 379
 380         DBG("Kernel session started");
 381
 382         return 0;
 383
 384 error:
 385         return ret;
 386 }
 387
 388 /*
 389  * Make a kernel wait to make sure in-flight probe have completed.
 390  */
 391 void kernel_wait_quiescent(int fd)
 392 {
 393         int ret;
 394
 395         DBG("Kernel quiescent wait on %d", fd);
 396
 397         ret = kernctl_wait_quiescent(fd);
 398         if (ret < 0) {
 399                 PERROR("wait quiescent ioctl");
 400                 ERR("Kernel quiescent wait failed");
 401         }
 402 }
 403
 404 /*
 405  * Kernel calibrate
 406  */
 407 int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
 408 {
 409         int ret;
 410
 411         ret = kernctl_calibrate(fd, calibrate);
 412         if (ret < 0) {
 413                 PERROR("calibrate ioctl");
 414                 return -1;
 415         }
 416
 417         return 0;
 418 }
 419
 420
 421 /*
 422  *  Force flush buffer of metadata.
 423  */
 424 int kernel_metadata_flush_buffer(int fd)
 425 {
 426         int ret;
 427
 428         ret = kernctl_buffer_flush(fd);
 429         if (ret < 0) {
 430                 ERR("Fail to flush metadata buffers %d (ret: %d", fd, ret);
 431         }
 432
 433         return 0;
 434 }
 435
 436 /*
 437  * Force flush buffer for channel.
 438  */
 439 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
 440 {
 441         int ret;
 442         struct ltt_kernel_stream *stream;
 443
 444         DBG("Flush buffer for channel %s", channel->channel->name);
 445
 446         cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
 447                 DBG("Flushing channel stream %d", stream->fd);
 448                 ret = kernctl_buffer_flush(stream->fd);
 449                 if (ret < 0) {
 450                         PERROR("ioctl");
 451                         ERR("Fail to flush buffer for stream %d (ret: %d)",
 452                                         stream->fd, ret);
 453                 }
 454         }
 455
 456         return 0;
 457 }
 458
 459 /*
 460  * Stop tracing session.
 461  */
 462 int kernel_stop_session(struct ltt_kernel_session *session)
 463 {
 464         int ret;
 465
 466         ret = kernctl_stop_session(session->fd);
 467         if (ret < 0) {
 468                 goto error;
 469         }
 470
 471         DBG("Kernel session stopped");
 472
 473         return 0;
 474
 475 error:
 476         return ret;
 477 }
 478
 479 /*
 480  * Open stream of channel, register it to the kernel tracer and add it
 481  * to the stream list of the channel.
 482  *
 483  * Return the number of created stream. Else, a negative value.
 484  */
 485 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 486 {
 487         int ret;
 488         struct ltt_kernel_stream *lks;
 489
 490         while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
 491                 lks = trace_kernel_create_stream();
 492                 if (lks == NULL) {
 493                         ret = close(ret);
 494                         if (ret) {
 495                                 PERROR("close");
 496                         }
 497                         goto error;
 498                 }
 499
 500                 lks->fd = ret;
 501                 /* Prevent fd duplication after execlp() */
 502                 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 503                 if (ret < 0) {
 504                         PERROR("fcntl session fd");
 505                 }
 506
 507                 ret = asprintf(&lks->pathname, "%s/%s_%d",
 508                                 channel->pathname, channel->channel->name, channel->stream_count);
 509                 if (ret < 0) {
 510                         PERROR("asprintf kernel create stream");
 511                         goto error;
 512                 }
 513
 514                 /* Add stream to channe stream list */
 515                 cds_list_add(&lks->list, &channel->stream_list.head);
 516                 channel->stream_count++;
 517
 518                 DBG("Kernel stream %d created (fd: %d, state: %d, path: %s)",
 519                                 channel->stream_count, lks->fd, lks->state, lks->pathname);
 520         }
 521
 522         return channel->stream_count;
 523
 524 error:
 525         return -1;
 526 }
 527
 528 /*
 529  * Open the metadata stream and set it to the kernel session.
 530  */
 531 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
 532 {
 533         int ret;
 534
 535         ret = kernctl_create_stream(session->metadata->fd);
 536         if (ret < 0) {
 537                 PERROR("kernel create metadata stream");
 538                 goto error;
 539         }
 540
 541         DBG("Kernel metadata stream created (fd: %d)", ret);
 542         session->metadata_stream_fd = ret;
 543         /* Prevent fd duplication after execlp() */
 544         ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
 545         if (ret < 0) {
 546                 PERROR("fcntl session fd");
 547         }
 548
 549         return 0;
 550
 551 error:
 552         return -1;
 553 }
 554
 555 /*
 556  * Get the event list from the kernel tracer and return the number of elements.
 557  */
 558 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 559 {
 560         int fd, pos, ret;
 561         char *event;
 562         size_t nbmem, count = 0;
 563         ssize_t size;
 564         FILE *fp;
 565         struct lttng_event *elist;
 566
 567         fd = kernctl_tracepoint_list(tracer_fd);
 568         if (fd < 0) {
 569                 PERROR("kernel tracepoint list");
 570                 goto error;
 571         }
 572
 573         fp = fdopen(fd, "r");
 574         if (fp == NULL) {
 575                 PERROR("kernel tracepoint list fdopen");
 576                 goto error_fp;
 577         }
 578
 579         /*
 580          * Init memory size counter
 581          * See kernel-ctl.h for explanation of this value
 582          */
 583         nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
 584         elist = zmalloc(sizeof(struct lttng_event) * nbmem);
 585
 586         while ((size = fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos)) == 1) {
 587                 if (count >= nbmem) {
 588                         DBG("Reallocating event list from %zu to %zu bytes", nbmem,
 589                                         nbmem * 2);
 590                         /* Double the size */
 591                         nbmem <<= 1;
 592                         elist = realloc(elist, nbmem * sizeof(struct lttng_event));
 593                         if (elist == NULL) {
 594                                 PERROR("realloc list events");
 595                                 count = -ENOMEM;
 596                                 goto end;
 597                         }
 598                 }
 599                 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
 600                 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 601                 elist[count].enabled = -1;
 602                 count++;
 603         }
 604
 605         *events = elist;
 606         DBG("Kernel list events done (%zu events)", count);
 607 end:
 608         ret = fclose(fp);       /* closes both fp and fd */
 609         if (ret) {
 610                 PERROR("fclose");
 611         }
 612         return count;
 613
 614 error_fp:
 615         ret = close(fd);
 616         if (ret) {
 617                 PERROR("close");
 618         }
 619 error:
 620         return -1;
 621 }
 622
 623 /*
 624  * Get kernel version and validate it.
 625  */
 626 int kernel_validate_version(int tracer_fd)
 627 {
 628         int ret;
 629         struct lttng_kernel_tracer_version version;
 630
 631         ret = kernctl_tracer_version(tracer_fd, &version);
 632         if (ret < 0) {
 633                 ERR("Failed at getting the lttng-modules version");
 634                 goto error;
 635         }
 636
 637         /* Validate version */
 638         if (version.major != KERN_MODULES_PRE_MAJOR
 639                 && version.major != KERN_MODULES_MAJOR) {
 640                 goto error_version;
 641         }
 642
 643         DBG2("Kernel tracer version validated (major version %d)", version.major);
 644         return 0;
 645
 646 error_version:
 647         ERR("Kernel major version %d is not compatible (supporting <= %d)",
 648                         version.major, KERN_MODULES_MAJOR)
 649         ret = -1;
 650
 651 error:
 652         return ret;
 653 }
 654
 655 /*
 656  * Kernel work-arounds called at the start of sessiond main().
 657  */
 658 int init_kernel_workarounds(void)
 659 {
 660         int ret;
 661         FILE *fp;
 662
 663         /*
 664          * boot_id needs to be read once before being used concurrently
 665          * to deal with a Linux kernel race. A fix is proposed for
 666          * upstream, but the work-around is needed for older kernels.
 667          */
 668         fp = fopen("/proc/sys/kernel/random/boot_id", "r");
 669         if (!fp) {
 670                 goto end_boot_id;
 671         }
 672         while (!feof(fp)) {
 673                 char buf[37] = "";
 674
 675                 ret = fread(buf, 1, sizeof(buf), fp);
 676                 if (ret < 0) {
 677                         /* Ignore error, we don't really care */
 678                 }
 679         }
 680         ret = fclose(fp);
 681         if (ret) {
 682                 PERROR("fclose");
 683         }
 684 end_boot_id:
 685         return 0;
 686 }