tools/perf/util/header.c

   1 #define _LARGEFILE64_SOURCE
   2 #define _FILE_OFFSET_BITS 64
   3
   4 #include <sys/types.h>
   5 #include <byteswap.h>
   6 #include <unistd.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <linux/list.h>
  10 #include <linux/kernel.h>
  11
  12 #include "util.h"
  13 #include "header.h"
  14 #include "../perf.h"
  15 #include "trace-event.h"
  16 #include "session.h"
  17 #include "symbol.h"
  18 #include "debug.h"
  19
  20 /*
  21  * Create new perf.data header attribute:
  22  */
  23 struct perf_header_attr *perf_header_attr__new(struct perf_event_attr *attr)
  24 {
  25         struct perf_header_attr *self = malloc(sizeof(*self));
  26
  27         if (self != NULL) {
  28                 self->attr = *attr;
  29                 self->ids  = 0;
  30                 self->size = 1;
  31                 self->id   = malloc(sizeof(u64));
  32                 if (self->id == NULL) {
  33                         free(self);
  34                         self = NULL;
  35                 }
  36         }
  37
  38         return self;
  39 }
  40
  41 void perf_header_attr__delete(struct perf_header_attr *self)
  42 {
  43         free(self->id);
  44         free(self);
  45 }
  46
  47 int perf_header_attr__add_id(struct perf_header_attr *self, u64 id)
  48 {
  49         int pos = self->ids;
  50
  51         self->ids++;
  52         if (self->ids > self->size) {
  53                 int nsize = self->size * 2;
  54                 u64 *nid = realloc(self->id, nsize * sizeof(u64));
  55
  56                 if (nid == NULL)
  57                         return -1;
  58
  59                 self->size = nsize;
  60                 self->id = nid;
  61         }
  62         self->id[pos] = id;
  63         return 0;
  64 }
  65
  66 int perf_header__init(struct perf_header *self)
  67 {
  68         self->size = 1;
  69         self->attr = malloc(sizeof(void *));
  70         return self->attr == NULL ? -ENOMEM : 0;
  71 }
  72
  73 void perf_header__exit(struct perf_header *self)
  74 {
  75         int i;
  76         for (i = 0; i < self->attrs; ++i)
  77                 perf_header_attr__delete(self->attr[i]);
  78         free(self->attr);
  79 }
  80
  81 int perf_header__add_attr(struct perf_header *self,
  82                           struct perf_header_attr *attr)
  83 {
  84         if (self->frozen)
  85                 return -1;
  86
  87         if (self->attrs == self->size) {
  88                 int nsize = self->size * 2;
  89                 struct perf_header_attr **nattr;
  90
  91                 nattr = realloc(self->attr, nsize * sizeof(void *));
  92                 if (nattr == NULL)
  93                         return -1;
  94
  95                 self->size = nsize;
  96                 self->attr = nattr;
  97         }
  98
  99         self->attr[self->attrs++] = attr;
 100         return 0;
 101 }
 102
 103 #define MAX_EVENT_NAME 64
 104
 105 struct perf_trace_event_type {
 106         u64     event_id;
 107         char    name[MAX_EVENT_NAME];
 108 };
 109
 110 static int event_count;
 111 static struct perf_trace_event_type *events;
 112
 113 int perf_header__push_event(u64 id, const char *name)
 114 {
 115         if (strlen(name) > MAX_EVENT_NAME)
 116                 pr_warning("Event %s will be truncated\n", name);
 117
 118         if (!events) {
 119                 events = malloc(sizeof(struct perf_trace_event_type));
 120                 if (events == NULL)
 121                         return -ENOMEM;
 122         } else {
 123                 struct perf_trace_event_type *nevents;
 124
 125                 nevents = realloc(events, (event_count + 1) * sizeof(*events));
 126                 if (nevents == NULL)
 127                         return -ENOMEM;
 128                 events = nevents;
 129         }
 130         memset(&events[event_count], 0, sizeof(struct perf_trace_event_type));
 131         events[event_count].event_id = id;
 132         strncpy(events[event_count].name, name, MAX_EVENT_NAME - 1);
 133         event_count++;
 134         return 0;
 135 }
 136
 137 char *perf_header__find_event(u64 id)
 138 {
 139         int i;
 140         for (i = 0 ; i < event_count; i++) {
 141                 if (events[i].event_id == id)
 142                         return events[i].name;
 143         }
 144         return NULL;
 145 }
 146
 147 static const char *__perf_magic = "PERFFILE";
 148
 149 #define PERF_MAGIC      (*(u64 *)__perf_magic)
 150
 151 struct perf_file_attr {
 152         struct perf_event_attr  attr;
 153         struct perf_file_section        ids;
 154 };
 155
 156 void perf_header__set_feat(struct perf_header *self, int feat)
 157 {
 158         set_bit(feat, self->adds_features);
 159 }
 160
 161 bool perf_header__has_feat(const struct perf_header *self, int feat)
 162 {
 163         return test_bit(feat, self->adds_features);
 164 }
 165
 166 static int do_write(int fd, const void *buf, size_t size)
 167 {
 168         while (size) {
 169                 int ret = write(fd, buf, size);
 170
 171                 if (ret < 0)
 172                         return -errno;
 173
 174                 size -= ret;
 175                 buf += ret;
 176         }
 177
 178         return 0;
 179 }
 180
 181 #define NAME_ALIGN 64
 182
 183 static int write_padded(int fd, const void *bf, size_t count,
 184                         size_t count_aligned)
 185 {
 186         static const char zero_buf[NAME_ALIGN];
 187         int err = do_write(fd, bf, count);
 188
 189         if (!err)
 190                 err = do_write(fd, zero_buf, count_aligned - count);
 191
 192         return err;
 193 }
 194
 195 #define dsos__for_each_with_build_id(pos, head) \
 196         list_for_each_entry(pos, head, node)    \
 197                 if (!pos->has_build_id)         \
 198                         continue;               \
 199                 else
 200
 201 static int __dsos__write_buildid_table(struct list_head *head, u16 misc, int fd)
 202 {
 203         struct dso *pos;
 204
 205         dsos__for_each_with_build_id(pos, head) {
 206                 int err;
 207                 struct build_id_event b;
 208                 size_t len;
 209
 210                 if (!pos->hit)
 211                         continue;
 212                 len = pos->long_name_len + 1;
 213                 len = ALIGN(len, NAME_ALIGN);
 214                 memset(&b, 0, sizeof(b));
 215                 memcpy(&b.build_id, pos->build_id, sizeof(pos->build_id));
 216                 b.header.misc = misc;
 217                 b.header.size = sizeof(b) + len;
 218                 err = do_write(fd, &b, sizeof(b));
 219                 if (err < 0)
 220                         return err;
 221                 err = write_padded(fd, pos->long_name,
 222                                    pos->long_name_len + 1, len);
 223                 if (err < 0)
 224                         return err;
 225         }
 226
 227         return 0;
 228 }
 229
 230 static int dsos__write_buildid_table(int fd)
 231 {
 232         int err = __dsos__write_buildid_table(&dsos__kernel,
 233                                               PERF_RECORD_MISC_KERNEL, fd);
 234         if (err == 0)
 235                 err = __dsos__write_buildid_table(&dsos__user,
 236                                                   PERF_RECORD_MISC_USER, fd);
 237         return err;
 238 }
 239
 240 int build_id_cache__add_s(const char *sbuild_id, const char *debugdir,
 241                           const char *name, bool is_kallsyms)
 242 {
 243         const size_t size = PATH_MAX;
 244         char *filename = malloc(size),
 245              *linkname = malloc(size), *targetname;
 246         int len, err = -1;
 247
 248         if (filename == NULL || linkname == NULL)
 249                 goto out_free;
 250
 251         len = snprintf(filename, size, "%s%s%s",
 252                        debugdir, is_kallsyms ? "/" : "", name);
 253         if (mkdir_p(filename, 0755))
 254                 goto out_free;
 255
 256         snprintf(filename + len, sizeof(filename) - len, "/%s", sbuild_id);
 257
 258         if (access(filename, F_OK)) {
 259                 if (is_kallsyms) {
 260                          if (copyfile("/proc/kallsyms", filename))
 261                                 goto out_free;
 262                 } else if (link(name, filename) && copyfile(name, filename))
 263                         goto out_free;
 264         }
 265
 266         len = snprintf(linkname, size, "%s/.build-id/%.2s",
 267                        debugdir, sbuild_id);
 268
 269         if (access(linkname, X_OK) && mkdir_p(linkname, 0755))
 270                 goto out_free;
 271
 272         snprintf(linkname + len, size - len, "/%s", sbuild_id + 2);
 273         targetname = filename + strlen(debugdir) - 5;
 274         memcpy(targetname, "../..", 5);
 275
 276         if (symlink(targetname, linkname) == 0)
 277                 err = 0;
 278 out_free:
 279         free(filename);
 280         free(linkname);
 281         return err;
 282 }
 283
 284 static int build_id_cache__add_b(const u8 *build_id, size_t build_id_size,
 285                                  const char *name, const char *debugdir,
 286                                  bool is_kallsyms)
 287 {
 288         char sbuild_id[BUILD_ID_SIZE * 2 + 1];
 289
 290         build_id__sprintf(build_id, build_id_size, sbuild_id);
 291
 292         return build_id_cache__add_s(sbuild_id, debugdir, name, is_kallsyms);
 293 }
 294
 295 int build_id_cache__remove_s(const char *sbuild_id, const char *debugdir)
 296 {
 297         const size_t size = PATH_MAX;
 298         char *filename = malloc(size),
 299              *linkname = malloc(size);
 300         int err = -1;
 301
 302         if (filename == NULL || linkname == NULL)
 303                 goto out_free;
 304
 305         snprintf(linkname, size, "%s/.build-id/%.2s/%s",
 306                  debugdir, sbuild_id, sbuild_id + 2);
 307
 308         if (access(linkname, F_OK))
 309                 goto out_free;
 310
 311         if (readlink(linkname, filename, size) < 0)
 312                 goto out_free;
 313
 314         if (unlink(linkname))
 315                 goto out_free;
 316
 317         /*
 318          * Since the link is relative, we must make it absolute:
 319          */
 320         snprintf(linkname, size, "%s/.build-id/%.2s/%s",
 321                  debugdir, sbuild_id, filename);
 322
 323         if (unlink(linkname))
 324                 goto out_free;
 325
 326         err = 0;
 327 out_free:
 328         free(filename);
 329         free(linkname);
 330         return err;
 331 }
 332
 333 static int dso__cache_build_id(struct dso *self, const char *debugdir)
 334 {
 335         bool is_kallsyms = self->kernel && self->long_name[0] != '/';
 336
 337         return build_id_cache__add_b(self->build_id, sizeof(self->build_id),
 338                                      self->long_name, debugdir, is_kallsyms);
 339 }
 340
 341 static int __dsos__cache_build_ids(struct list_head *head, const char *debugdir)
 342 {
 343         struct dso *pos;
 344         int err = 0;
 345
 346         dsos__for_each_with_build_id(pos, head)
 347                 if (dso__cache_build_id(pos, debugdir))
 348                         err = -1;
 349
 350         return err;
 351 }
 352
 353 static int dsos__cache_build_ids(void)
 354 {
 355         int err_kernel, err_user;
 356         char debugdir[PATH_MAX];
 357
 358         snprintf(debugdir, sizeof(debugdir), "%s/%s", getenv("HOME"),
 359                  DEBUG_CACHE_DIR);
 360
 361         if (mkdir(debugdir, 0755) != 0 && errno != EEXIST)
 362                 return -1;
 363
 364         err_kernel = __dsos__cache_build_ids(&dsos__kernel, debugdir);
 365         err_user   = __dsos__cache_build_ids(&dsos__user, debugdir);
 366         return err_kernel || err_user ? -1 : 0;
 367 }
 368
 369 static int perf_header__adds_write(struct perf_header *self, int fd)
 370 {
 371         int nr_sections;
 372         struct perf_file_section *feat_sec;
 373         int sec_size;
 374         u64 sec_start;
 375         int idx = 0, err;
 376
 377         if (dsos__read_build_ids(true))
 378                 perf_header__set_feat(self, HEADER_BUILD_ID);
 379
 380         nr_sections = bitmap_weight(self->adds_features, HEADER_FEAT_BITS);
 381         if (!nr_sections)
 382                 return 0;
 383
 384         feat_sec = calloc(sizeof(*feat_sec), nr_sections);
 385         if (feat_sec == NULL)
 386                 return -ENOMEM;
 387
 388         sec_size = sizeof(*feat_sec) * nr_sections;
 389
 390         sec_start = self->data_offset + self->data_size;
 391         lseek64(fd, sec_start + sec_size, SEEK_SET);
 392
 393         if (perf_header__has_feat(self, HEADER_TRACE_INFO)) {
 394                 struct perf_file_section *trace_sec;
 395
 396                 trace_sec = &feat_sec[idx++];
 397
 398                 /* Write trace info */
 399                 trace_sec->offset = lseek64(fd, 0, SEEK_CUR);
 400                 read_tracing_data(fd, attrs, nr_counters);
 401                 trace_sec->size = lseek64(fd, 0, SEEK_CUR) - trace_sec->offset;
 402         }
 403
 404
 405         if (perf_header__has_feat(self, HEADER_BUILD_ID)) {
 406                 struct perf_file_section *buildid_sec;
 407
 408                 buildid_sec = &feat_sec[idx++];
 409
 410                 /* Write build-ids */
 411                 buildid_sec->offset = lseek64(fd, 0, SEEK_CUR);
 412                 err = dsos__write_buildid_table(fd);
 413                 if (err < 0) {
 414                         pr_debug("failed to write buildid table\n");
 415                         goto out_free;
 416                 }
 417                 buildid_sec->size = lseek64(fd, 0, SEEK_CUR) -
 418                                             buildid_sec->offset;
 419                 dsos__cache_build_ids();
 420         }
 421
 422         lseek64(fd, sec_start, SEEK_SET);
 423         err = do_write(fd, feat_sec, sec_size);
 424         if (err < 0)
 425                 pr_debug("failed to write feature section\n");
 426 out_free:
 427         free(feat_sec);
 428         return err;
 429 }
 430
 431 int perf_header__write(struct perf_header *self, int fd, bool at_exit)
 432 {
 433         struct perf_file_header f_header;
 434         struct perf_file_attr   f_attr;
 435         struct perf_header_attr *attr;
 436         int i, err;
 437
 438         lseek(fd, sizeof(f_header), SEEK_SET);
 439
 440
 441         for (i = 0; i < self->attrs; i++) {
 442                 attr = self->attr[i];
 443
 444                 attr->id_offset = lseek(fd, 0, SEEK_CUR);
 445                 err = do_write(fd, attr->id, attr->ids * sizeof(u64));
 446                 if (err < 0) {
 447                         pr_debug("failed to write perf header\n");
 448                         return err;
 449                 }
 450         }
 451
 452
 453         self->attr_offset = lseek(fd, 0, SEEK_CUR);
 454
 455         for (i = 0; i < self->attrs; i++) {
 456                 attr = self->attr[i];
 457
 458                 f_attr = (struct perf_file_attr){
 459                         .attr = attr->attr,
 460                         .ids  = {
 461                                 .offset = attr->id_offset,
 462                                 .size   = attr->ids * sizeof(u64),
 463                         }
 464                 };
 465                 err = do_write(fd, &f_attr, sizeof(f_attr));
 466                 if (err < 0) {
 467                         pr_debug("failed to write perf header attribute\n");
 468                         return err;
 469                 }
 470         }
 471
 472         self->event_offset = lseek(fd, 0, SEEK_CUR);
 473         self->event_size = event_count * sizeof(struct perf_trace_event_type);
 474         if (events) {
 475                 err = do_write(fd, events, self->event_size);
 476                 if (err < 0) {
 477                         pr_debug("failed to write perf header events\n");
 478                         return err;
 479                 }
 480         }
 481
 482         self->data_offset = lseek(fd, 0, SEEK_CUR);
 483
 484         if (at_exit) {
 485                 err = perf_header__adds_write(self, fd);
 486                 if (err < 0)
 487                         return err;
 488         }
 489
 490         f_header = (struct perf_file_header){
 491                 .magic     = PERF_MAGIC,
 492                 .size      = sizeof(f_header),
 493                 .attr_size = sizeof(f_attr),
 494                 .attrs = {
 495                         .offset = self->attr_offset,
 496                         .size   = self->attrs * sizeof(f_attr),
 497                 },
 498                 .data = {
 499                         .offset = self->data_offset,
 500                         .size   = self->data_size,
 501                 },
 502                 .event_types = {
 503                         .offset = self->event_offset,
 504                         .size   = self->event_size,
 505                 },
 506         };
 507
 508         memcpy(&f_header.adds_features, &self->adds_features, sizeof(self->adds_features));
 509
 510         lseek(fd, 0, SEEK_SET);
 511         err = do_write(fd, &f_header, sizeof(f_header));
 512         if (err < 0) {
 513                 pr_debug("failed to write perf header\n");
 514                 return err;
 515         }
 516         lseek64(fd, self->data_offset + self->data_size, SEEK_SET);
 517
 518         self->frozen = 1;
 519         return 0;
 520 }
 521
 522 static int do_read(int fd, void *buf, size_t size)
 523 {
 524         while (size) {
 525                 int ret = read(fd, buf, size);
 526
 527                 if (ret <= 0)
 528                         return -1;
 529
 530                 size -= ret;
 531                 buf += ret;
 532         }
 533
 534         return 0;
 535 }
 536
 537 static int perf_header__getbuffer64(struct perf_header *self,
 538                                     int fd, void *buf, size_t size)
 539 {
 540         if (do_read(fd, buf, size))
 541                 return -1;
 542
 543         if (self->needs_swap)
 544                 mem_bswap_64(buf, size);
 545
 546         return 0;
 547 }
 548
 549 int perf_header__process_sections(struct perf_header *self, int fd,
 550                                   int (*process)(struct perf_file_section *self,
 551                                                  struct perf_header *ph,
 552                                                  int feat, int fd))
 553 {
 554         struct perf_file_section *feat_sec;
 555         int nr_sections;
 556         int sec_size;
 557         int idx = 0;
 558         int err = -1, feat = 1;
 559
 560         nr_sections = bitmap_weight(self->adds_features, HEADER_FEAT_BITS);
 561         if (!nr_sections)
 562                 return 0;
 563
 564         feat_sec = calloc(sizeof(*feat_sec), nr_sections);
 565         if (!feat_sec)
 566                 return -1;
 567
 568         sec_size = sizeof(*feat_sec) * nr_sections;
 569
 570         lseek64(fd, self->data_offset + self->data_size, SEEK_SET);
 571
 572         if (perf_header__getbuffer64(self, fd, feat_sec, sec_size))
 573                 goto out_free;
 574
 575         err = 0;
 576         while (idx < nr_sections && feat < HEADER_LAST_FEATURE) {
 577                 if (perf_header__has_feat(self, feat)) {
 578                         struct perf_file_section *sec = &feat_sec[idx++];
 579
 580                         err = process(sec, self, feat, fd);
 581                         if (err < 0)
 582                                 break;
 583                 }
 584                 ++feat;
 585         }
 586 out_free:
 587         free(feat_sec);
 588         return err;
 589 }
 590
 591 int perf_file_header__read(struct perf_file_header *self,
 592                            struct perf_header *ph, int fd)
 593 {
 594         lseek(fd, 0, SEEK_SET);
 595
 596         if (do_read(fd, self, sizeof(*self)) ||
 597             memcmp(&self->magic, __perf_magic, sizeof(self->magic)))
 598                 return -1;
 599
 600         if (self->attr_size != sizeof(struct perf_file_attr)) {
 601                 u64 attr_size = bswap_64(self->attr_size);
 602
 603                 if (attr_size != sizeof(struct perf_file_attr))
 604                         return -1;
 605
 606                 mem_bswap_64(self, offsetof(struct perf_file_header,
 607                                             adds_features));
 608                 ph->needs_swap = true;
 609         }
 610
 611         if (self->size != sizeof(*self)) {
 612                 /* Support the previous format */
 613                 if (self->size == offsetof(typeof(*self), adds_features))
 614                         bitmap_zero(self->adds_features, HEADER_FEAT_BITS);
 615                 else
 616                         return -1;
 617         }
 618
 619         memcpy(&ph->adds_features, &self->adds_features,
 620                sizeof(ph->adds_features));
 621         /*
 622          * FIXME: hack that assumes that if we need swap the perf.data file
 623          * may be coming from an arch with a different word-size, ergo different
 624          * DEFINE_BITMAP format, investigate more later, but for now its mostly
 625          * safe to assume that we have a build-id section. Trace files probably
 626          * have several other issues in this realm anyway...
 627          */
 628         if (ph->needs_swap) {
 629                 memset(&ph->adds_features, 0, sizeof(ph->adds_features));
 630                 perf_header__set_feat(ph, HEADER_BUILD_ID);
 631         }
 632
 633         ph->event_offset = self->event_types.offset;
 634         ph->event_size   = self->event_types.size;
 635         ph->data_offset  = self->data.offset;
 636         ph->data_size    = self->data.size;
 637         return 0;
 638 }
 639
 640 static int perf_file_section__process(struct perf_file_section *self,
 641                                       struct perf_header *ph,
 642                                       int feat, int fd)
 643 {
 644         if (lseek64(fd, self->offset, SEEK_SET) < 0) {
 645                 pr_debug("Failed to lseek to %Ld offset for feature %d, "
 646                          "continuing...\n", self->offset, feat);
 647                 return 0;
 648         }
 649
 650         switch (feat) {
 651         case HEADER_TRACE_INFO:
 652                 trace_report(fd);
 653                 break;
 654
 655         case HEADER_BUILD_ID:
 656                 if (perf_header__read_build_ids(ph, fd, self->offset, self->size))
 657                         pr_debug("Failed to read buildids, continuing...\n");
 658                 break;
 659         default:
 660                 pr_debug("unknown feature %d, continuing...\n", feat);
 661         }
 662
 663         return 0;
 664 }
 665
 666 int perf_header__read(struct perf_header *self, int fd)
 667 {
 668         struct perf_file_header f_header;
 669         struct perf_file_attr   f_attr;
 670         u64                     f_id;
 671         int nr_attrs, nr_ids, i, j;
 672
 673         if (perf_file_header__read(&f_header, self, fd) < 0) {
 674                 pr_debug("incompatible file format\n");
 675                 return -EINVAL;
 676         }
 677
 678         nr_attrs = f_header.attrs.size / sizeof(f_attr);
 679         lseek(fd, f_header.attrs.offset, SEEK_SET);
 680
 681         for (i = 0; i < nr_attrs; i++) {
 682                 struct perf_header_attr *attr;
 683                 off_t tmp;
 684
 685                 if (perf_header__getbuffer64(self, fd, &f_attr, sizeof(f_attr)))
 686                         goto out_errno;
 687
 688                 tmp = lseek(fd, 0, SEEK_CUR);
 689
 690                 attr = perf_header_attr__new(&f_attr.attr);
 691                 if (attr == NULL)
 692                          return -ENOMEM;
 693
 694                 nr_ids = f_attr.ids.size / sizeof(u64);
 695                 lseek(fd, f_attr.ids.offset, SEEK_SET);
 696
 697                 for (j = 0; j < nr_ids; j++) {
 698                         if (perf_header__getbuffer64(self, fd, &f_id, sizeof(f_id)))
 699                                 goto out_errno;
 700
 701                         if (perf_header_attr__add_id(attr, f_id) < 0) {
 702                                 perf_header_attr__delete(attr);
 703                                 return -ENOMEM;
 704                         }
 705                 }
 706                 if (perf_header__add_attr(self, attr) < 0) {
 707                         perf_header_attr__delete(attr);
 708                         return -ENOMEM;
 709                 }
 710
 711                 lseek(fd, tmp, SEEK_SET);
 712         }
 713
 714         if (f_header.event_types.size) {
 715                 lseek(fd, f_header.event_types.offset, SEEK_SET);
 716                 events = malloc(f_header.event_types.size);
 717                 if (events == NULL)
 718                         return -ENOMEM;
 719                 if (perf_header__getbuffer64(self, fd, events,
 720                                              f_header.event_types.size))
 721                         goto out_errno;
 722                 event_count =  f_header.event_types.size / sizeof(struct perf_trace_event_type);
 723         }
 724
 725         perf_header__process_sections(self, fd, perf_file_section__process);
 726
 727         lseek(fd, self->data_offset, SEEK_SET);
 728
 729         self->frozen = 1;
 730         return 0;
 731 out_errno:
 732         return -errno;
 733 }
 734
 735 u64 perf_header__sample_type(struct perf_header *header)
 736 {
 737         u64 type = 0;
 738         int i;
 739
 740         for (i = 0; i < header->attrs; i++) {
 741                 struct perf_header_attr *attr = header->attr[i];
 742
 743                 if (!type)
 744                         type = attr->attr.sample_type;
 745                 else if (type != attr->attr.sample_type)
 746                         die("non matching sample_type");
 747         }
 748
 749         return type;
 750 }
 751
 752 struct perf_event_attr *
 753 perf_header__find_attr(u64 id, struct perf_header *header)
 754 {
 755         int i;
 756
 757         for (i = 0; i < header->attrs; i++) {
 758                 struct perf_header_attr *attr = header->attr[i];
 759                 int j;
 760
 761                 for (j = 0; j < attr->ids; j++) {
 762                         if (attr->id[j] == id)
 763                                 return &attr->attr;
 764                 }
 765         }
 766
 767         return NULL;
 768 }