tools/perf/util/header.c

   1 #define _FILE_OFFSET_BITS 64
   2
   3 #include <sys/types.h>
   4 #include <byteswap.h>
   5 #include <unistd.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <linux/list.h>
   9 #include <linux/kernel.h>
  10
  11 #include "util.h"
  12 #include "header.h"
  13 #include "../perf.h"
  14 #include "trace-event.h"
  15 #include "session.h"
  16 #include "symbol.h"
  17 #include "debug.h"
  18
  19 /*
  20  * Create new perf.data header attribute:
  21  */
  22 struct perf_header_attr *perf_header_attr__new(struct perf_event_attr *attr)
  23 {
  24         struct perf_header_attr *self = malloc(sizeof(*self));
  25
  26         if (self != NULL) {
  27                 self->attr = *attr;
  28                 self->ids  = 0;
  29                 self->size = 1;
  30                 self->id   = malloc(sizeof(u64));
  31                 if (self->id == NULL) {
  32                         free(self);
  33                         self = NULL;
  34                 }
  35         }
  36
  37         return self;
  38 }
  39
  40 void perf_header_attr__delete(struct perf_header_attr *self)
  41 {
  42         free(self->id);
  43         free(self);
  44 }
  45
  46 int perf_header_attr__add_id(struct perf_header_attr *self, u64 id)
  47 {
  48         int pos = self->ids;
  49
  50         self->ids++;
  51         if (self->ids > self->size) {
  52                 int nsize = self->size * 2;
  53                 u64 *nid = realloc(self->id, nsize * sizeof(u64));
  54
  55                 if (nid == NULL)
  56                         return -1;
  57
  58                 self->size = nsize;
  59                 self->id = nid;
  60         }
  61         self->id[pos] = id;
  62         return 0;
  63 }
  64
  65 int perf_header__init(struct perf_header *self)
  66 {
  67         self->size = 1;
  68         self->attr = malloc(sizeof(void *));
  69         return self->attr == NULL ? -ENOMEM : 0;
  70 }
  71
  72 void perf_header__exit(struct perf_header *self)
  73 {
  74         int i;
  75         for (i = 0; i < self->attrs; ++i)
  76                 perf_header_attr__delete(self->attr[i]);
  77         free(self->attr);
  78 }
  79
  80 int perf_header__add_attr(struct perf_header *self,
  81                           struct perf_header_attr *attr)
  82 {
  83         if (self->frozen)
  84                 return -1;
  85
  86         if (self->attrs == self->size) {
  87                 int nsize = self->size * 2;
  88                 struct perf_header_attr **nattr;
  89
  90                 nattr = realloc(self->attr, nsize * sizeof(void *));
  91                 if (nattr == NULL)
  92                         return -1;
  93
  94                 self->size = nsize;
  95                 self->attr = nattr;
  96         }
  97
  98         self->attr[self->attrs++] = attr;
  99         return 0;
 100 }
 101
 102 #define MAX_EVENT_NAME 64
 103
 104 struct perf_trace_event_type {
 105         u64     event_id;
 106         char    name[MAX_EVENT_NAME];
 107 };
 108
 109 static int event_count;
 110 static struct perf_trace_event_type *events;
 111
 112 int perf_header__push_event(u64 id, const char *name)
 113 {
 114         if (strlen(name) > MAX_EVENT_NAME)
 115                 pr_warning("Event %s will be truncated\n", name);
 116
 117         if (!events) {
 118                 events = malloc(sizeof(struct perf_trace_event_type));
 119                 if (events == NULL)
 120                         return -ENOMEM;
 121         } else {
 122                 struct perf_trace_event_type *nevents;
 123
 124                 nevents = realloc(events, (event_count + 1) * sizeof(*events));
 125                 if (nevents == NULL)
 126                         return -ENOMEM;
 127                 events = nevents;
 128         }
 129         memset(&events[event_count], 0, sizeof(struct perf_trace_event_type));
 130         events[event_count].event_id = id;
 131         strncpy(events[event_count].name, name, MAX_EVENT_NAME - 1);
 132         event_count++;
 133         return 0;
 134 }
 135
 136 char *perf_header__find_event(u64 id)
 137 {
 138         int i;
 139         for (i = 0 ; i < event_count; i++) {
 140                 if (events[i].event_id == id)
 141                         return events[i].name;
 142         }
 143         return NULL;
 144 }
 145
 146 static const char *__perf_magic = "PERFFILE";
 147
 148 #define PERF_MAGIC      (*(u64 *)__perf_magic)
 149
 150 struct perf_file_attr {
 151         struct perf_event_attr  attr;
 152         struct perf_file_section        ids;
 153 };
 154
 155 void perf_header__set_feat(struct perf_header *self, int feat)
 156 {
 157         set_bit(feat, self->adds_features);
 158 }
 159
 160 bool perf_header__has_feat(const struct perf_header *self, int feat)
 161 {
 162         return test_bit(feat, self->adds_features);
 163 }
 164
 165 static int do_write(int fd, const void *buf, size_t size)
 166 {
 167         while (size) {
 168                 int ret = write(fd, buf, size);
 169
 170                 if (ret < 0)
 171                         return -errno;
 172
 173                 size -= ret;
 174                 buf += ret;
 175         }
 176
 177         return 0;
 178 }
 179
 180 #define NAME_ALIGN 64
 181
 182 static int write_padded(int fd, const void *bf, size_t count,
 183                         size_t count_aligned)
 184 {
 185         static const char zero_buf[NAME_ALIGN];
 186         int err = do_write(fd, bf, count);
 187
 188         if (!err)
 189                 err = do_write(fd, zero_buf, count_aligned - count);
 190
 191         return err;
 192 }
 193
 194 #define dsos__for_each_with_build_id(pos, head) \
 195         list_for_each_entry(pos, head, node)    \
 196                 if (!pos->has_build_id)         \
 197                         continue;               \
 198                 else
 199
 200 static int __dsos__write_buildid_table(struct list_head *head, u16 misc, int fd)
 201 {
 202         struct dso *pos;
 203
 204         dsos__for_each_with_build_id(pos, head) {
 205                 int err;
 206                 struct build_id_event b;
 207                 size_t len;
 208
 209                 if (!pos->hit)
 210                         continue;
 211                 len = pos->long_name_len + 1;
 212                 len = ALIGN(len, NAME_ALIGN);
 213                 memset(&b, 0, sizeof(b));
 214                 memcpy(&b.build_id, pos->build_id, sizeof(pos->build_id));
 215                 b.header.misc = misc;
 216                 b.header.size = sizeof(b) + len;
 217                 err = do_write(fd, &b, sizeof(b));
 218                 if (err < 0)
 219                         return err;
 220                 err = write_padded(fd, pos->long_name,
 221                                    pos->long_name_len + 1, len);
 222                 if (err < 0)
 223                         return err;
 224         }
 225
 226         return 0;
 227 }
 228
 229 static int dsos__write_buildid_table(int fd)
 230 {
 231         int err = __dsos__write_buildid_table(&dsos__kernel,
 232                                               PERF_RECORD_MISC_KERNEL, fd);
 233         if (err == 0)
 234                 err = __dsos__write_buildid_table(&dsos__user,
 235                                                   PERF_RECORD_MISC_USER, fd);
 236         return err;
 237 }
 238
 239 int build_id_cache__add_s(const char *sbuild_id, const char *debugdir,
 240                           const char *name, bool is_kallsyms)
 241 {
 242         const size_t size = PATH_MAX;
 243         char *filename = malloc(size),
 244              *linkname = malloc(size), *targetname;
 245         int len, err = -1;
 246
 247         if (filename == NULL || linkname == NULL)
 248                 goto out_free;
 249
 250         len = snprintf(filename, size, "%s%s%s",
 251                        debugdir, is_kallsyms ? "/" : "", name);
 252         if (mkdir_p(filename, 0755))
 253                 goto out_free;
 254
 255         snprintf(filename + len, sizeof(filename) - len, "/%s", sbuild_id);
 256
 257         if (access(filename, F_OK)) {
 258                 if (is_kallsyms) {
 259                          if (copyfile("/proc/kallsyms", filename))
 260                                 goto out_free;
 261                 } else if (link(name, filename) && copyfile(name, filename))
 262                         goto out_free;
 263         }
 264
 265         len = snprintf(linkname, size, "%s/.build-id/%.2s",
 266                        debugdir, sbuild_id);
 267
 268         if (access(linkname, X_OK) && mkdir_p(linkname, 0755))
 269                 goto out_free;
 270
 271         snprintf(linkname + len, size - len, "/%s", sbuild_id + 2);
 272         targetname = filename + strlen(debugdir) - 5;
 273         memcpy(targetname, "../..", 5);
 274
 275         if (symlink(targetname, linkname) == 0)
 276                 err = 0;
 277 out_free:
 278         free(filename);
 279         free(linkname);
 280         return err;
 281 }
 282
 283 static int build_id_cache__add_b(const u8 *build_id, size_t build_id_size,
 284                                  const char *name, const char *debugdir,
 285                                  bool is_kallsyms)
 286 {
 287         char sbuild_id[BUILD_ID_SIZE * 2 + 1];
 288
 289         build_id__sprintf(build_id, build_id_size, sbuild_id);
 290
 291         return build_id_cache__add_s(sbuild_id, debugdir, name, is_kallsyms);
 292 }
 293
 294 int build_id_cache__remove_s(const char *sbuild_id, const char *debugdir)
 295 {
 296         const size_t size = PATH_MAX;
 297         char *filename = malloc(size),
 298              *linkname = malloc(size);
 299         int err = -1;
 300
 301         if (filename == NULL || linkname == NULL)
 302                 goto out_free;
 303
 304         snprintf(linkname, size, "%s/.build-id/%.2s/%s",
 305                  debugdir, sbuild_id, sbuild_id + 2);
 306
 307         if (access(linkname, F_OK))
 308                 goto out_free;
 309
 310         if (readlink(linkname, filename, size) < 0)
 311                 goto out_free;
 312
 313         if (unlink(linkname))
 314                 goto out_free;
 315
 316         /*
 317          * Since the link is relative, we must make it absolute:
 318          */
 319         snprintf(linkname, size, "%s/.build-id/%.2s/%s",
 320                  debugdir, sbuild_id, filename);
 321
 322         if (unlink(linkname))
 323                 goto out_free;
 324
 325         err = 0;
 326 out_free:
 327         free(filename);
 328         free(linkname);
 329         return err;
 330 }
 331
 332 static int dso__cache_build_id(struct dso *self, const char *debugdir)
 333 {
 334         bool is_kallsyms = self->kernel && self->long_name[0] != '/';
 335
 336         return build_id_cache__add_b(self->build_id, sizeof(self->build_id),
 337                                      self->long_name, debugdir, is_kallsyms);
 338 }
 339
 340 static int __dsos__cache_build_ids(struct list_head *head, const char *debugdir)
 341 {
 342         struct dso *pos;
 343         int err = 0;
 344
 345         dsos__for_each_with_build_id(pos, head)
 346                 if (dso__cache_build_id(pos, debugdir))
 347                         err = -1;
 348
 349         return err;
 350 }
 351
 352 static int dsos__cache_build_ids(void)
 353 {
 354         int err_kernel, err_user;
 355         char debugdir[PATH_MAX];
 356
 357         snprintf(debugdir, sizeof(debugdir), "%s/%s", getenv("HOME"),
 358                  DEBUG_CACHE_DIR);
 359
 360         if (mkdir(debugdir, 0755) != 0 && errno != EEXIST)
 361                 return -1;
 362
 363         err_kernel = __dsos__cache_build_ids(&dsos__kernel, debugdir);
 364         err_user   = __dsos__cache_build_ids(&dsos__user, debugdir);
 365         return err_kernel || err_user ? -1 : 0;
 366 }
 367
 368 static int perf_header__adds_write(struct perf_header *self, int fd)
 369 {
 370         int nr_sections;
 371         struct perf_file_section *feat_sec;
 372         int sec_size;
 373         u64 sec_start;
 374         int idx = 0, err;
 375
 376         if (dsos__read_build_ids(true))
 377                 perf_header__set_feat(self, HEADER_BUILD_ID);
 378
 379         nr_sections = bitmap_weight(self->adds_features, HEADER_FEAT_BITS);
 380         if (!nr_sections)
 381                 return 0;
 382
 383         feat_sec = calloc(sizeof(*feat_sec), nr_sections);
 384         if (feat_sec == NULL)
 385                 return -ENOMEM;
 386
 387         sec_size = sizeof(*feat_sec) * nr_sections;
 388
 389         sec_start = self->data_offset + self->data_size;
 390         lseek(fd, sec_start + sec_size, SEEK_SET);
 391
 392         if (perf_header__has_feat(self, HEADER_TRACE_INFO)) {
 393                 struct perf_file_section *trace_sec;
 394
 395                 trace_sec = &feat_sec[idx++];
 396
 397                 /* Write trace info */
 398                 trace_sec->offset = lseek(fd, 0, SEEK_CUR);
 399                 read_tracing_data(fd, attrs, nr_counters);
 400                 trace_sec->size = lseek(fd, 0, SEEK_CUR) - trace_sec->offset;
 401         }
 402
 403
 404         if (perf_header__has_feat(self, HEADER_BUILD_ID)) {
 405                 struct perf_file_section *buildid_sec;
 406
 407                 buildid_sec = &feat_sec[idx++];
 408
 409                 /* Write build-ids */
 410                 buildid_sec->offset = lseek(fd, 0, SEEK_CUR);
 411                 err = dsos__write_buildid_table(fd);
 412                 if (err < 0) {
 413                         pr_debug("failed to write buildid table\n");
 414                         goto out_free;
 415                 }
 416                 buildid_sec->size = lseek(fd, 0, SEEK_CUR) -
 417                                           buildid_sec->offset;
 418                 dsos__cache_build_ids();
 419         }
 420
 421         lseek(fd, sec_start, SEEK_SET);
 422         err = do_write(fd, feat_sec, sec_size);
 423         if (err < 0)
 424                 pr_debug("failed to write feature section\n");
 425 out_free:
 426         free(feat_sec);
 427         return err;
 428 }
 429
 430 int perf_header__write(struct perf_header *self, int fd, bool at_exit)
 431 {
 432         struct perf_file_header f_header;
 433         struct perf_file_attr   f_attr;
 434         struct perf_header_attr *attr;
 435         int i, err;
 436
 437         lseek(fd, sizeof(f_header), SEEK_SET);
 438
 439
 440         for (i = 0; i < self->attrs; i++) {
 441                 attr = self->attr[i];
 442
 443                 attr->id_offset = lseek(fd, 0, SEEK_CUR);
 444                 err = do_write(fd, attr->id, attr->ids * sizeof(u64));
 445                 if (err < 0) {
 446                         pr_debug("failed to write perf header\n");
 447                         return err;
 448                 }
 449         }
 450
 451
 452         self->attr_offset = lseek(fd, 0, SEEK_CUR);
 453
 454         for (i = 0; i < self->attrs; i++) {
 455                 attr = self->attr[i];
 456
 457                 f_attr = (struct perf_file_attr){
 458                         .attr = attr->attr,
 459                         .ids  = {
 460                                 .offset = attr->id_offset,
 461                                 .size   = attr->ids * sizeof(u64),
 462                         }
 463                 };
 464                 err = do_write(fd, &f_attr, sizeof(f_attr));
 465                 if (err < 0) {
 466                         pr_debug("failed to write perf header attribute\n");
 467                         return err;
 468                 }
 469         }
 470
 471         self->event_offset = lseek(fd, 0, SEEK_CUR);
 472         self->event_size = event_count * sizeof(struct perf_trace_event_type);
 473         if (events) {
 474                 err = do_write(fd, events, self->event_size);
 475                 if (err < 0) {
 476                         pr_debug("failed to write perf header events\n");
 477                         return err;
 478                 }
 479         }
 480
 481         self->data_offset = lseek(fd, 0, SEEK_CUR);
 482
 483         if (at_exit) {
 484                 err = perf_header__adds_write(self, fd);
 485                 if (err < 0)
 486                         return err;
 487         }
 488
 489         f_header = (struct perf_file_header){
 490                 .magic     = PERF_MAGIC,
 491                 .size      = sizeof(f_header),
 492                 .attr_size = sizeof(f_attr),
 493                 .attrs = {
 494                         .offset = self->attr_offset,
 495                         .size   = self->attrs * sizeof(f_attr),
 496                 },
 497                 .data = {
 498                         .offset = self->data_offset,
 499                         .size   = self->data_size,
 500                 },
 501                 .event_types = {
 502                         .offset = self->event_offset,
 503                         .size   = self->event_size,
 504                 },
 505         };
 506
 507         memcpy(&f_header.adds_features, &self->adds_features, sizeof(self->adds_features));
 508
 509         lseek(fd, 0, SEEK_SET);
 510         err = do_write(fd, &f_header, sizeof(f_header));
 511         if (err < 0) {
 512                 pr_debug("failed to write perf header\n");
 513                 return err;
 514         }
 515         lseek(fd, self->data_offset + self->data_size, SEEK_SET);
 516
 517         self->frozen = 1;
 518         return 0;
 519 }
 520
 521 static int do_read(int fd, void *buf, size_t size)
 522 {
 523         while (size) {
 524                 int ret = read(fd, buf, size);
 525
 526                 if (ret <= 0)
 527                         return -1;
 528
 529                 size -= ret;
 530                 buf += ret;
 531         }
 532
 533         return 0;
 534 }
 535
 536 static int perf_header__getbuffer64(struct perf_header *self,
 537                                     int fd, void *buf, size_t size)
 538 {
 539         if (do_read(fd, buf, size))
 540                 return -1;
 541
 542         if (self->needs_swap)
 543                 mem_bswap_64(buf, size);
 544
 545         return 0;
 546 }
 547
 548 int perf_header__process_sections(struct perf_header *self, int fd,
 549                                   int (*process)(struct perf_file_section *self,
 550                                                  struct perf_header *ph,
 551                                                  int feat, int fd))
 552 {
 553         struct perf_file_section *feat_sec;
 554         int nr_sections;
 555         int sec_size;
 556         int idx = 0;
 557         int err = -1, feat = 1;
 558
 559         nr_sections = bitmap_weight(self->adds_features, HEADER_FEAT_BITS);
 560         if (!nr_sections)
 561                 return 0;
 562
 563         feat_sec = calloc(sizeof(*feat_sec), nr_sections);
 564         if (!feat_sec)
 565                 return -1;
 566
 567         sec_size = sizeof(*feat_sec) * nr_sections;
 568
 569         lseek(fd, self->data_offset + self->data_size, SEEK_SET);
 570
 571         if (perf_header__getbuffer64(self, fd, feat_sec, sec_size))
 572                 goto out_free;
 573
 574         err = 0;
 575         while (idx < nr_sections && feat < HEADER_LAST_FEATURE) {
 576                 if (perf_header__has_feat(self, feat)) {
 577                         struct perf_file_section *sec = &feat_sec[idx++];
 578
 579                         err = process(sec, self, feat, fd);
 580                         if (err < 0)
 581                                 break;
 582                 }
 583                 ++feat;
 584         }
 585 out_free:
 586         free(feat_sec);
 587         return err;
 588 }
 589
 590 int perf_file_header__read(struct perf_file_header *self,
 591                            struct perf_header *ph, int fd)
 592 {
 593         lseek(fd, 0, SEEK_SET);
 594
 595         if (do_read(fd, self, sizeof(*self)) ||
 596             memcmp(&self->magic, __perf_magic, sizeof(self->magic)))
 597                 return -1;
 598
 599         if (self->attr_size != sizeof(struct perf_file_attr)) {
 600                 u64 attr_size = bswap_64(self->attr_size);
 601
 602                 if (attr_size != sizeof(struct perf_file_attr))
 603                         return -1;
 604
 605                 mem_bswap_64(self, offsetof(struct perf_file_header,
 606                                             adds_features));
 607                 ph->needs_swap = true;
 608         }
 609
 610         if (self->size != sizeof(*self)) {
 611                 /* Support the previous format */
 612                 if (self->size == offsetof(typeof(*self), adds_features))
 613                         bitmap_zero(self->adds_features, HEADER_FEAT_BITS);
 614                 else
 615                         return -1;
 616         }
 617
 618         memcpy(&ph->adds_features, &self->adds_features,
 619                sizeof(ph->adds_features));
 620         /*
 621          * FIXME: hack that assumes that if we need swap the perf.data file
 622          * may be coming from an arch with a different word-size, ergo different
 623          * DEFINE_BITMAP format, investigate more later, but for now its mostly
 624          * safe to assume that we have a build-id section. Trace files probably
 625          * have several other issues in this realm anyway...
 626          */
 627         if (ph->needs_swap) {
 628                 memset(&ph->adds_features, 0, sizeof(ph->adds_features));
 629                 perf_header__set_feat(ph, HEADER_BUILD_ID);
 630         }
 631
 632         ph->event_offset = self->event_types.offset;
 633         ph->event_size   = self->event_types.size;
 634         ph->data_offset  = self->data.offset;
 635         ph->data_size    = self->data.size;
 636         return 0;
 637 }
 638
 639 static int perf_file_section__process(struct perf_file_section *self,
 640                                       struct perf_header *ph,
 641                                       int feat, int fd)
 642 {
 643         if (lseek(fd, self->offset, SEEK_SET) == (off_t)-1) {
 644                 pr_debug("Failed to lseek to %Ld offset for feature %d, "
 645                          "continuing...\n", self->offset, feat);
 646                 return 0;
 647         }
 648
 649         switch (feat) {
 650         case HEADER_TRACE_INFO:
 651                 trace_report(fd);
 652                 break;
 653
 654         case HEADER_BUILD_ID:
 655                 if (perf_header__read_build_ids(ph, fd, self->offset, self->size))
 656                         pr_debug("Failed to read buildids, continuing...\n");
 657                 break;
 658         default:
 659                 pr_debug("unknown feature %d, continuing...\n", feat);
 660         }
 661
 662         return 0;
 663 }
 664
 665 int perf_header__read(struct perf_header *self, int fd)
 666 {
 667         struct perf_file_header f_header;
 668         struct perf_file_attr   f_attr;
 669         u64                     f_id;
 670         int nr_attrs, nr_ids, i, j;
 671
 672         if (perf_file_header__read(&f_header, self, fd) < 0) {
 673                 pr_debug("incompatible file format\n");
 674                 return -EINVAL;
 675         }
 676
 677         nr_attrs = f_header.attrs.size / sizeof(f_attr);
 678         lseek(fd, f_header.attrs.offset, SEEK_SET);
 679
 680         for (i = 0; i < nr_attrs; i++) {
 681                 struct perf_header_attr *attr;
 682                 off_t tmp;
 683
 684                 if (perf_header__getbuffer64(self, fd, &f_attr, sizeof(f_attr)))
 685                         goto out_errno;
 686
 687                 tmp = lseek(fd, 0, SEEK_CUR);
 688
 689                 attr = perf_header_attr__new(&f_attr.attr);
 690                 if (attr == NULL)
 691                          return -ENOMEM;
 692
 693                 nr_ids = f_attr.ids.size / sizeof(u64);
 694                 lseek(fd, f_attr.ids.offset, SEEK_SET);
 695
 696                 for (j = 0; j < nr_ids; j++) {
 697                         if (perf_header__getbuffer64(self, fd, &f_id, sizeof(f_id)))
 698                                 goto out_errno;
 699
 700                         if (perf_header_attr__add_id(attr, f_id) < 0) {
 701                                 perf_header_attr__delete(attr);
 702                                 return -ENOMEM;
 703                         }
 704                 }
 705                 if (perf_header__add_attr(self, attr) < 0) {
 706                         perf_header_attr__delete(attr);
 707                         return -ENOMEM;
 708                 }
 709
 710                 lseek(fd, tmp, SEEK_SET);
 711         }
 712
 713         if (f_header.event_types.size) {
 714                 lseek(fd, f_header.event_types.offset, SEEK_SET);
 715                 events = malloc(f_header.event_types.size);
 716                 if (events == NULL)
 717                         return -ENOMEM;
 718                 if (perf_header__getbuffer64(self, fd, events,
 719                                              f_header.event_types.size))
 720                         goto out_errno;
 721                 event_count =  f_header.event_types.size / sizeof(struct perf_trace_event_type);
 722         }
 723
 724         perf_header__process_sections(self, fd, perf_file_section__process);
 725
 726         lseek(fd, self->data_offset, SEEK_SET);
 727
 728         self->frozen = 1;
 729         return 0;
 730 out_errno:
 731         return -errno;
 732 }
 733
 734 u64 perf_header__sample_type(struct perf_header *header)
 735 {
 736         u64 type = 0;
 737         int i;
 738
 739         for (i = 0; i < header->attrs; i++) {
 740                 struct perf_header_attr *attr = header->attr[i];
 741
 742                 if (!type)
 743                         type = attr->attr.sample_type;
 744                 else if (type != attr->attr.sample_type)
 745                         die("non matching sample_type");
 746         }
 747
 748         return type;
 749 }
 750
 751 struct perf_event_attr *
 752 perf_header__find_attr(u64 id, struct perf_header *header)
 753 {
 754         int i;
 755
 756         for (i = 0; i < header->attrs; i++) {
 757                 struct perf_header_attr *attr = header->attr[i];
 758                 int j;
 759
 760                 for (j = 0; j < attr->ids; j++) {
 761                         if (attr->id[j] == id)
 762                                 return &attr->attr;
 763                 }
 764         }
 765
 766         return NULL;
 767 }