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
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; only version 2
   7  * of the License.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include <common/common.h>
  28 #include <common/kernel-ctl/kernel-ctl.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                 goto add_list;
 212         }
 213
 214         event->fd = ret;
 215         /* Prevent fd duplication after execlp() */
 216         ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
 217         if (ret < 0) {
 218                 perror("fcntl session fd");
 219         }
 220
 221 add_list:
 222         /* Add event to event list */
 223         cds_list_add(&event->list, &channel->events_list.head);
 224         channel->event_count++;
 225
 226         DBG("Event %s created (fd: %d)", ev->name, event->fd);
 227
 228         return 0;
 229
 230 free_event:
 231         free(event);
 232 error:
 233         return ret;
 234 }
 235
 236 /*
 237  * Disable a kernel channel.
 238  */
 239 int kernel_disable_channel(struct ltt_kernel_channel *chan)
 240 {
 241         int ret;
 242
 243         ret = kernctl_disable(chan->fd);
 244         if (ret < 0) {
 245                 perror("disable chan ioctl");
 246                 ret = errno;
 247                 goto error;
 248         }
 249
 250         chan->enabled = 0;
 251         DBG("Kernel channel %s disabled (fd: %d)", chan->channel->name, chan->fd);
 252
 253         return 0;
 254
 255 error:
 256         return ret;
 257 }
 258
 259 /*
 260  * Enable a kernel channel.
 261  */
 262 int kernel_enable_channel(struct ltt_kernel_channel *chan)
 263 {
 264         int ret;
 265
 266         ret = kernctl_enable(chan->fd);
 267         if (ret < 0 && errno != EEXIST) {
 268                 perror("Enable kernel chan");
 269                 goto error;
 270         }
 271
 272         chan->enabled = 1;
 273         DBG("Kernel channel %s enabled (fd: %d)", chan->channel->name, chan->fd);
 274
 275         return 0;
 276
 277 error:
 278         return ret;
 279 }
 280
 281 /*
 282  * Enable a kernel event.
 283  */
 284 int kernel_enable_event(struct ltt_kernel_event *event)
 285 {
 286         int ret;
 287
 288         ret = kernctl_enable(event->fd);
 289         if (ret < 0 && errno != EEXIST) {
 290                 perror("enable kernel event");
 291                 goto error;
 292         }
 293
 294         event->enabled = 1;
 295         DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
 296
 297         return 0;
 298
 299 error:
 300         return ret;
 301 }
 302
 303 /*
 304  * Disable a kernel event.
 305  */
 306 int kernel_disable_event(struct ltt_kernel_event *event)
 307 {
 308         int ret;
 309
 310         ret = kernctl_disable(event->fd);
 311         if (ret < 0 && errno != EEXIST) {
 312                 perror("disable kernel event");
 313                 goto error;
 314         }
 315
 316         event->enabled = 0;
 317         DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
 318
 319         return 0;
 320
 321 error:
 322         return ret;
 323 }
 324
 325 /*
 326  * Create kernel metadata, open from the kernel tracer and add it to the
 327  * kernel session.
 328  */
 329 int kernel_open_metadata(struct ltt_kernel_session *session, char *path)
 330 {
 331         int ret;
 332         struct ltt_kernel_metadata *lkm;
 333
 334         /* Allocate kernel metadata */
 335         lkm = trace_kernel_create_metadata(path);
 336         if (lkm == NULL) {
 337                 goto error;
 338         }
 339
 340         /* Kernel tracer metadata creation */
 341         ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
 342         if (ret < 0) {
 343                 goto error;
 344         }
 345
 346         lkm->fd = ret;
 347         /* Prevent fd duplication after execlp() */
 348         ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
 349         if (ret < 0) {
 350                 perror("fcntl session fd");
 351         }
 352
 353         session->metadata = lkm;
 354
 355         DBG("Kernel metadata opened (fd: %d and path: %s)", lkm->fd, lkm->pathname);
 356
 357         return 0;
 358
 359 error:
 360         return -1;
 361 }
 362
 363 /*
 364  * Start tracing session.
 365  */
 366 int kernel_start_session(struct ltt_kernel_session *session)
 367 {
 368         int ret;
 369
 370         ret = kernctl_start_session(session->fd);
 371         if (ret < 0) {
 372                 perror("ioctl start session");
 373                 goto error;
 374         }
 375
 376         DBG("Kernel session started");
 377
 378         return 0;
 379
 380 error:
 381         return ret;
 382 }
 383
 384 /*
 385  * Make a kernel wait to make sure in-flight probe have completed.
 386  */
 387 void kernel_wait_quiescent(int fd)
 388 {
 389         int ret;
 390
 391         DBG("Kernel quiescent wait on %d", fd);
 392
 393         ret = kernctl_wait_quiescent(fd);
 394         if (ret < 0) {
 395                 perror("wait quiescent ioctl");
 396                 ERR("Kernel quiescent wait failed");
 397         }
 398 }
 399
 400 /*
 401  * Kernel calibrate
 402  */
 403 int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
 404 {
 405         int ret;
 406
 407         ret = kernctl_calibrate(fd, calibrate);
 408         if (ret < 0) {
 409                 perror("calibrate ioctl");
 410                 return -1;
 411         }
 412
 413         return 0;
 414 }
 415
 416
 417 /*
 418  *  Force flush buffer of metadata.
 419  */
 420 int kernel_metadata_flush_buffer(int fd)
 421 {
 422         int ret;
 423
 424         ret = kernctl_buffer_flush(fd);
 425         if (ret < 0) {
 426                 ERR("Fail to flush metadata buffers %d (ret: %d", fd, ret);
 427         }
 428
 429         return 0;
 430 }
 431
 432 /*
 433  * Force flush buffer for channel.
 434  */
 435 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
 436 {
 437         int ret;
 438         struct ltt_kernel_stream *stream;
 439
 440         DBG("Flush buffer for channel %s", channel->channel->name);
 441
 442         cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
 443                 DBG("Flushing channel stream %d", stream->fd);
 444                 ret = kernctl_buffer_flush(stream->fd);
 445                 if (ret < 0) {
 446                         perror("ioctl");
 447                         ERR("Fail to flush buffer for stream %d (ret: %d)",
 448                                         stream->fd, ret);
 449                 }
 450         }
 451
 452         return 0;
 453 }
 454
 455 /*
 456  * Stop tracing session.
 457  */
 458 int kernel_stop_session(struct ltt_kernel_session *session)
 459 {
 460         int ret;
 461
 462         ret = kernctl_stop_session(session->fd);
 463         if (ret < 0) {
 464                 goto error;
 465         }
 466
 467         DBG("Kernel session stopped");
 468
 469         return 0;
 470
 471 error:
 472         return ret;
 473 }
 474
 475 /*
 476  * Open stream of channel, register it to the kernel tracer and add it
 477  * to the stream list of the channel.
 478  *
 479  * Return the number of created stream. Else, a negative value.
 480  */
 481 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 482 {
 483         int ret;
 484         struct ltt_kernel_stream *lks;
 485
 486         while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
 487                 lks = trace_kernel_create_stream();
 488                 if (lks == NULL) {
 489                         close(ret);
 490                         goto error;
 491                 }
 492
 493                 lks->fd = ret;
 494                 /* Prevent fd duplication after execlp() */
 495                 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
 496                 if (ret < 0) {
 497                         perror("fcntl session fd");
 498                 }
 499
 500                 ret = asprintf(&lks->pathname, "%s/%s_%d",
 501                                 channel->pathname, channel->channel->name, channel->stream_count);
 502                 if (ret < 0) {
 503                         perror("asprintf kernel create stream");
 504                         goto error;
 505                 }
 506
 507                 /* Add stream to channe stream list */
 508                 cds_list_add(&lks->list, &channel->stream_list.head);
 509                 channel->stream_count++;
 510
 511                 DBG("Kernel stream %d created (fd: %d, state: %d, path: %s)",
 512                                 channel->stream_count, lks->fd, lks->state, lks->pathname);
 513         }
 514
 515         return channel->stream_count;
 516
 517 error:
 518         return -1;
 519 }
 520
 521 /*
 522  * Open the metadata stream and set it to the kernel session.
 523  */
 524 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
 525 {
 526         int ret;
 527
 528         ret = kernctl_create_stream(session->metadata->fd);
 529         if (ret < 0) {
 530                 perror("kernel create metadata stream");
 531                 goto error;
 532         }
 533
 534         DBG("Kernel metadata stream created (fd: %d)", ret);
 535         session->metadata_stream_fd = ret;
 536         /* Prevent fd duplication after execlp() */
 537         ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
 538         if (ret < 0) {
 539                 perror("fcntl session fd");
 540         }
 541
 542         return 0;
 543
 544 error:
 545         return -1;
 546 }
 547
 548 /*
 549  * Get the event list from the kernel tracer and return the number of elements.
 550  */
 551 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
 552 {
 553         int fd, pos;
 554         char *event;
 555         size_t nbmem, count = 0;
 556         ssize_t size;
 557         FILE *fp;
 558         struct lttng_event *elist;
 559
 560         fd = kernctl_tracepoint_list(tracer_fd);
 561         if (fd < 0) {
 562                 perror("kernel tracepoint list");
 563                 goto error;
 564         }
 565
 566         fp = fdopen(fd, "r");
 567         if (fp == NULL) {
 568                 perror("kernel tracepoint list fdopen");
 569                 goto error_fp;
 570         }
 571
 572         /*
 573          * Init memory size counter
 574          * See kernel-ctl.h for explanation of this value
 575          */
 576         nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
 577         elist = zmalloc(sizeof(struct lttng_event) * nbmem);
 578
 579         while ((size = fscanf(fp, "event { name = %m[^;]; };%n\n", &event, &pos)) == 1) {
 580                 if (count >= nbmem) {
 581                         DBG("Reallocating event list from %zu to %zu bytes", nbmem,
 582                                         nbmem * 2);
 583                         /* Double the size */
 584                         nbmem <<= 1;
 585                         elist = realloc(elist, nbmem * sizeof(struct lttng_event));
 586                         if (elist == NULL) {
 587                                 perror("realloc list events");
 588                                 count = -ENOMEM;
 589                                 goto end;
 590                         }
 591                 }
 592                 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
 593                 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 594                 elist[count].enabled = -1;
 595                 count++;
 596         }
 597
 598         *events = elist;
 599         DBG("Kernel list events done (%zu events)", count);
 600 end:
 601         fclose(fp);     /* closes both fp and fd */
 602         return count;
 603
 604 error_fp:
 605         close(fd);
 606 error:
 607         return -1;
 608 }
 609
 610 /*
 611  * Get kernel version and validate it.
 612  */
 613 int kernel_validate_version(int tracer_fd)
 614 {
 615         int ret;
 616         struct lttng_kernel_tracer_version version;
 617
 618         ret = kernctl_tracer_version(tracer_fd, &version);
 619         if (ret < 0) {
 620                 ERR("Failed at getting the lttng-modules version");
 621                 goto error;
 622         }
 623
 624         /* Validate version */
 625         if (version.major != KERN_MODULES_PRE_MAJOR
 626                 && version.major != KERN_MODULES_MAJOR) {
 627                 goto error_version;
 628         }
 629
 630         DBG2("Kernel tracer version validated (major version %d)", version.major);
 631         return 0;
 632
 633 error_version:
 634         ERR("Kernel major version %d is not compatible (supporting <= %d)",
 635                         version.major, KERN_MODULES_MAJOR)
 636         ret = -1;
 637
 638 error:
 639         return ret;
 640 }
 641
 642 /*
 643  * Kernel work-arounds called at the start of sessiond main().
 644  */
 645 int init_kernel_workarounds(void)
 646 {
 647         int ret;
 648         FILE *fp;
 649
 650         /*
 651          * boot_id needs to be read once before being used concurrently
 652          * to deal with a Linux kernel race. A fix is proposed for
 653          * upstream, but the work-around is needed for older kernels.
 654          */
 655         fp = fopen("/proc/sys/kernel/random/boot_id", "r");
 656         if (!fp) {
 657                 goto end_boot_id;
 658         }
 659         while (!feof(fp)) {
 660                 char buf[37] = "";
 661
 662                 ret = fread(buf, 1, sizeof(buf), fp);
 663                 if (ret < 0) {
 664                         /* Ignore error, we don't really care */
 665                 }
 666         }
 667         fclose(fp);
 668 end_boot_id:
 669
 670         return 0;
 671 }