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