SAFE public projects git trees. - safe/jmp/linux-2.6/blob - tools/perf/util/header.c

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