tools/perf/util/build-id.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * build-id.c
   4  *
   5  * build-id support
   6  *
   7  * Copyright (C) 2009, 2010 Red Hat Inc.
   8  * Copyright (C) 2009, 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
   9  */
  10 #include "util.h" // lsdir(), mkdir_p(), rm_rf()
  11 #include <dirent.h>
  12 #include <errno.h>
  13 #include <stdio.h>
  14 #include <sys/stat.h>
  15 #include <sys/types.h>
  16 #include "util/copyfile.h"
  17 #include "dso.h"
  18 #include "build-id.h"
  19 #include "event.h"
  20 #include "namespaces.h"
  21 #include "map.h"
  22 #include "symbol.h"
  23 #include "thread.h"
  24 #include <linux/kernel.h>
  25 #include "debug.h"
  26 #include "session.h"
  27 #include "tool.h"
  28 #include "header.h"
  29 #include "vdso.h"
  30 #include "path.h"
  31 #include "probe-file.h"
  32 #include "strlist.h"
  33
  34 #include <linux/ctype.h>
  35 #include <linux/zalloc.h>
  36
  37 static bool no_buildid_cache;
  38
  39 int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
  40                            union perf_event *event,
  41                            struct perf_sample *sample,
  42                            struct evsel *evsel __maybe_unused,
  43                            struct machine *machine)
  44 {
  45         struct addr_location al;
  46         struct thread *thread = machine__findnew_thread(machine, sample->pid,
  47                                                         sample->tid);
  48
  49         if (thread == NULL) {
  50                 pr_err("problem processing %d event, skipping it.\n",
  51                         event->header.type);
  52                 return -1;
  53         }
  54
  55         if (thread__find_map(thread, sample->cpumode, sample->ip, &al))
  56                 al.map->dso->hit = 1;
  57
  58         thread__put(thread);
  59         return 0;
  60 }
  61
  62 static int perf_event__exit_del_thread(struct perf_tool *tool __maybe_unused,
  63                                        union perf_event *event,
  64                                        struct perf_sample *sample
  65                                        __maybe_unused,
  66                                        struct machine *machine)
  67 {
  68         struct thread *thread = machine__findnew_thread(machine,
  69                                                         event->fork.pid,
  70                                                         event->fork.tid);
  71
  72         dump_printf("(%d:%d):(%d:%d)\n", event->fork.pid, event->fork.tid,
  73                     event->fork.ppid, event->fork.ptid);
  74
  75         if (thread) {
  76                 machine__remove_thread(machine, thread);
  77                 thread__put(thread);
  78         }
  79
  80         return 0;
  81 }
  82
  83 struct perf_tool build_id__mark_dso_hit_ops = {
  84         .sample = build_id__mark_dso_hit,
  85         .mmap   = perf_event__process_mmap,
  86         .mmap2  = perf_event__process_mmap2,
  87         .fork   = perf_event__process_fork,
  88         .exit   = perf_event__exit_del_thread,
  89         .attr            = perf_event__process_attr,
  90         .build_id        = perf_event__process_build_id,
  91         .ordered_events  = true,
  92 };
  93
  94 int build_id__sprintf(const u8 *build_id, int len, char *bf)
  95 {
  96         char *bid = bf;
  97         const u8 *raw = build_id;
  98         int i;
  99
 100         for (i = 0; i < len; ++i) {
 101                 sprintf(bid, "%02x", *raw);
 102                 ++raw;
 103                 bid += 2;
 104         }
 105
 106         return (bid - bf) + 1;
 107 }
 108
 109 int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id)
 110 {
 111         char notes[PATH_MAX];
 112         u8 build_id[BUILD_ID_SIZE];
 113         int ret;
 114
 115         if (!root_dir)
 116                 root_dir = "";
 117
 118         scnprintf(notes, sizeof(notes), "%s/sys/kernel/notes", root_dir);
 119
 120         ret = sysfs__read_build_id(notes, build_id, sizeof(build_id));
 121         if (ret < 0)
 122                 return ret;
 123
 124         return build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
 125 }
 126
 127 int filename__sprintf_build_id(const char *pathname, char *sbuild_id)
 128 {
 129         u8 build_id[BUILD_ID_SIZE];
 130         int ret;
 131
 132         ret = filename__read_build_id(pathname, build_id, sizeof(build_id));
 133         if (ret < 0)
 134                 return ret;
 135         else if (ret != sizeof(build_id))
 136                 return -EINVAL;
 137
 138         return build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
 139 }
 140
 141 /* asnprintf consolidates asprintf and snprintf */
 142 static int asnprintf(char **strp, size_t size, const char *fmt, ...)
 143 {
 144         va_list ap;
 145         int ret;
 146
 147         if (!strp)
 148                 return -EINVAL;
 149
 150         va_start(ap, fmt);
 151         if (*strp)
 152                 ret = vsnprintf(*strp, size, fmt, ap);
 153         else
 154                 ret = vasprintf(strp, fmt, ap);
 155         va_end(ap);
 156
 157         return ret;
 158 }
 159
 160 char *build_id_cache__kallsyms_path(const char *sbuild_id, char *bf,
 161                                     size_t size)
 162 {
 163         bool retry_old = true;
 164
 165         snprintf(bf, size, "%s/%s/%s/kallsyms",
 166                  buildid_dir, DSO__NAME_KALLSYMS, sbuild_id);
 167 retry:
 168         if (!access(bf, F_OK))
 169                 return bf;
 170         if (retry_old) {
 171                 /* Try old style kallsyms cache */
 172                 snprintf(bf, size, "%s/%s/%s",
 173                          buildid_dir, DSO__NAME_KALLSYMS, sbuild_id);
 174                 retry_old = false;
 175                 goto retry;
 176         }
 177
 178         return NULL;
 179 }
 180
 181 char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size)
 182 {
 183         char *tmp = bf;
 184         int ret = asnprintf(&bf, size, "%s/.build-id/%.2s/%s", buildid_dir,
 185                             sbuild_id, sbuild_id + 2);
 186         if (ret < 0 || (tmp && size < (unsigned int)ret))
 187                 return NULL;
 188         return bf;
 189 }
 190
 191 /* The caller is responsible to free the returned buffer. */
 192 char *build_id_cache__origname(const char *sbuild_id)
 193 {
 194         char *linkname;
 195         char buf[PATH_MAX];
 196         char *ret = NULL, *p;
 197         size_t offs = 5;        /* == strlen("../..") */
 198         ssize_t len;
 199
 200         linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
 201         if (!linkname)
 202                 return NULL;
 203
 204         len = readlink(linkname, buf, sizeof(buf) - 1);
 205         if (len <= 0)
 206                 goto out;
 207         buf[len] = '\0';
 208
 209         /* The link should be "../..<origpath>/<sbuild_id>" */
 210         p = strrchr(buf, '/');  /* Cut off the "/<sbuild_id>" */
 211         if (p && (p > buf + offs)) {
 212                 *p = '\0';
 213                 if (buf[offs + 1] == '[')
 214                         offs++; /*
 215                                  * This is a DSO name, like [kernel.kallsyms].
 216                                  * Skip the first '/', since this is not the
 217                                  * cache of a regular file.
 218                                  */
 219                 ret = strdup(buf + offs);       /* Skip "../..[/]" */
 220         }
 221 out:
 222         free(linkname);
 223         return ret;
 224 }
 225
 226 /* Check if the given build_id cache is valid on current running system */
 227 static bool build_id_cache__valid_id(char *sbuild_id)
 228 {
 229         char real_sbuild_id[SBUILD_ID_SIZE] = "";
 230         char *pathname;
 231         int ret = 0;
 232         bool result = false;
 233
 234         pathname = build_id_cache__origname(sbuild_id);
 235         if (!pathname)
 236                 return false;
 237
 238         if (!strcmp(pathname, DSO__NAME_KALLSYMS))
 239                 ret = sysfs__sprintf_build_id("/", real_sbuild_id);
 240         else if (pathname[0] == '/')
 241                 ret = filename__sprintf_build_id(pathname, real_sbuild_id);
 242         else
 243                 ret = -EINVAL;  /* Should we support other special DSO cache? */
 244         if (ret >= 0)
 245                 result = (strcmp(sbuild_id, real_sbuild_id) == 0);
 246         free(pathname);
 247
 248         return result;
 249 }
 250
 251 static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso,
 252                                             bool is_debug)
 253 {
 254         return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : (is_debug ?
 255             "debug" : "elf"));
 256 }
 257
 258 char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
 259                              bool is_debug)
 260 {
 261         bool is_kallsyms = dso__is_kallsyms((struct dso *)dso);
 262         bool is_vdso = dso__is_vdso((struct dso *)dso);
 263         char sbuild_id[SBUILD_ID_SIZE];
 264         char *linkname;
 265         bool alloc = (bf == NULL);
 266         int ret;
 267
 268         if (!dso->has_build_id)
 269                 return NULL;
 270
 271         build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);
 272         linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
 273         if (!linkname)
 274                 return NULL;
 275
 276         /* Check if old style build_id cache */
 277         if (is_regular_file(linkname))
 278                 ret = asnprintf(&bf, size, "%s", linkname);
 279         else
 280                 ret = asnprintf(&bf, size, "%s/%s", linkname,
 281                          build_id_cache__basename(is_kallsyms, is_vdso,
 282                                                   is_debug));
 283         if (ret < 0 || (!alloc && size < (unsigned int)ret))
 284                 bf = NULL;
 285         free(linkname);
 286
 287         return bf;
 288 }
 289
 290 #define dsos__for_each_with_build_id(pos, head) \
 291         list_for_each_entry(pos, head, node)    \
 292                 if (!pos->has_build_id)         \
 293                         continue;               \
 294                 else
 295
 296 static int write_buildid(const char *name, size_t name_len, u8 *build_id,
 297                          pid_t pid, u16 misc, struct feat_fd *fd)
 298 {
 299         int err;
 300         struct perf_record_header_build_id b;
 301         size_t len;
 302
 303         len = name_len + 1;
 304         len = PERF_ALIGN(len, NAME_ALIGN);
 305
 306         memset(&b, 0, sizeof(b));
 307         memcpy(&b.build_id, build_id, BUILD_ID_SIZE);
 308         b.pid = pid;
 309         b.header.misc = misc;
 310         b.header.size = sizeof(b) + len;
 311
 312         err = do_write(fd, &b, sizeof(b));
 313         if (err < 0)
 314                 return err;
 315
 316         return write_padded(fd, name, name_len + 1, len);
 317 }
 318
 319 static int machine__write_buildid_table(struct machine *machine,
 320                                         struct feat_fd *fd)
 321 {
 322         int err = 0;
 323         struct dso *pos;
 324         u16 kmisc = PERF_RECORD_MISC_KERNEL,
 325             umisc = PERF_RECORD_MISC_USER;
 326
 327         if (!machine__is_host(machine)) {
 328                 kmisc = PERF_RECORD_MISC_GUEST_KERNEL;
 329                 umisc = PERF_RECORD_MISC_GUEST_USER;
 330         }
 331
 332         dsos__for_each_with_build_id(pos, &machine->dsos.head) {
 333                 const char *name;
 334                 size_t name_len;
 335                 bool in_kernel = false;
 336
 337                 if (!pos->hit && !dso__is_vdso(pos))
 338                         continue;
 339
 340                 if (dso__is_vdso(pos)) {
 341                         name = pos->short_name;
 342                         name_len = pos->short_name_len;
 343                 } else if (dso__is_kcore(pos)) {
 344                         name = machine->mmap_name;
 345                         name_len = strlen(name);
 346                 } else {
 347                         name = pos->long_name;
 348                         name_len = pos->long_name_len;
 349                 }
 350
 351                 in_kernel = pos->kernel ||
 352                                 is_kernel_module(name,
 353                                         PERF_RECORD_MISC_CPUMODE_UNKNOWN);
 354                 err = write_buildid(name, name_len, pos->build_id, machine->pid,
 355                                     in_kernel ? kmisc : umisc, fd);
 356                 if (err)
 357                         break;
 358         }
 359
 360         return err;
 361 }
 362
 363 int perf_session__write_buildid_table(struct perf_session *session,
 364                                       struct feat_fd *fd)
 365 {
 366         struct rb_node *nd;
 367         int err = machine__write_buildid_table(&session->machines.host, fd);
 368
 369         if (err)
 370                 return err;
 371
 372         for (nd = rb_first_cached(&session->machines.guests); nd;
 373              nd = rb_next(nd)) {
 374                 struct machine *pos = rb_entry(nd, struct machine, rb_node);
 375                 err = machine__write_buildid_table(pos, fd);
 376                 if (err)
 377                         break;
 378         }
 379         return err;
 380 }
 381
 382 static int __dsos__hit_all(struct list_head *head)
 383 {
 384         struct dso *pos;
 385
 386         list_for_each_entry(pos, head, node)
 387                 pos->hit = true;
 388
 389         return 0;
 390 }
 391
 392 static int machine__hit_all_dsos(struct machine *machine)
 393 {
 394         return __dsos__hit_all(&machine->dsos.head);
 395 }
 396
 397 int dsos__hit_all(struct perf_session *session)
 398 {
 399         struct rb_node *nd;
 400         int err;
 401
 402         err = machine__hit_all_dsos(&session->machines.host);
 403         if (err)
 404                 return err;
 405
 406         for (nd = rb_first_cached(&session->machines.guests); nd;
 407              nd = rb_next(nd)) {
 408                 struct machine *pos = rb_entry(nd, struct machine, rb_node);
 409
 410                 err = machine__hit_all_dsos(pos);
 411                 if (err)
 412                         return err;
 413         }
 414
 415         return 0;
 416 }
 417
 418 void disable_buildid_cache(void)
 419 {
 420         no_buildid_cache = true;
 421 }
 422
 423 static bool lsdir_bid_head_filter(const char *name __maybe_unused,
 424                                   struct dirent *d)
 425 {
 426         return (strlen(d->d_name) == 2) &&
 427                 isxdigit(d->d_name[0]) && isxdigit(d->d_name[1]);
 428 }
 429
 430 static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
 431                                   struct dirent *d)
 432 {
 433         int i = 0;
 434         while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
 435                 i++;
 436         return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
 437 }
 438
 439 struct strlist *build_id_cache__list_all(bool validonly)
 440 {
 441         struct strlist *toplist, *linklist = NULL, *bidlist;
 442         struct str_node *nd, *nd2;
 443         char *topdir, *linkdir = NULL;
 444         char sbuild_id[SBUILD_ID_SIZE];
 445
 446         /* for filename__ functions */
 447         if (validonly)
 448                 symbol__init(NULL);
 449
 450         /* Open the top-level directory */
 451         if (asprintf(&topdir, "%s/.build-id/", buildid_dir) < 0)
 452                 return NULL;
 453
 454         bidlist = strlist__new(NULL, NULL);
 455         if (!bidlist)
 456                 goto out;
 457
 458         toplist = lsdir(topdir, lsdir_bid_head_filter);
 459         if (!toplist) {
 460                 pr_debug("Error in lsdir(%s): %d\n", topdir, errno);
 461                 /* If there is no buildid cache, return an empty list */
 462                 if (errno == ENOENT)
 463                         goto out;
 464                 goto err_out;
 465         }
 466
 467         strlist__for_each_entry(nd, toplist) {
 468                 if (asprintf(&linkdir, "%s/%s", topdir, nd->s) < 0)
 469                         goto err_out;
 470                 /* Open the lower-level directory */
 471                 linklist = lsdir(linkdir, lsdir_bid_tail_filter);
 472                 if (!linklist) {
 473                         pr_debug("Error in lsdir(%s): %d\n", linkdir, errno);
 474                         goto err_out;
 475                 }
 476                 strlist__for_each_entry(nd2, linklist) {
 477                         if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
 478                                      nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
 479                                 goto err_out;
 480                         if (validonly && !build_id_cache__valid_id(sbuild_id))
 481                                 continue;
 482                         if (strlist__add(bidlist, sbuild_id) < 0)
 483                                 goto err_out;
 484                 }
 485                 strlist__delete(linklist);
 486                 zfree(&linkdir);
 487         }
 488
 489 out_free:
 490         strlist__delete(toplist);
 491 out:
 492         free(topdir);
 493
 494         return bidlist;
 495
 496 err_out:
 497         strlist__delete(linklist);
 498         zfree(&linkdir);
 499         strlist__delete(bidlist);
 500         bidlist = NULL;
 501         goto out_free;
 502 }
 503
 504 static bool str_is_build_id(const char *maybe_sbuild_id, size_t len)
 505 {
 506         size_t i;
 507
 508         for (i = 0; i < len; i++) {
 509                 if (!isxdigit(maybe_sbuild_id[i]))
 510                         return false;
 511         }
 512         return true;
 513 }
 514
 515 /* Return the valid complete build-id */
 516 char *build_id_cache__complement(const char *incomplete_sbuild_id)
 517 {
 518         struct strlist *bidlist;
 519         struct str_node *nd, *cand = NULL;
 520         char *sbuild_id = NULL;
 521         size_t len = strlen(incomplete_sbuild_id);
 522
 523         if (len >= SBUILD_ID_SIZE ||
 524             !str_is_build_id(incomplete_sbuild_id, len))
 525                 return NULL;
 526
 527         bidlist = build_id_cache__list_all(true);
 528         if (!bidlist)
 529                 return NULL;
 530
 531         strlist__for_each_entry(nd, bidlist) {
 532                 if (strncmp(nd->s, incomplete_sbuild_id, len) != 0)
 533                         continue;
 534                 if (cand) {     /* Error: There are more than 2 candidates. */
 535                         cand = NULL;
 536                         break;
 537                 }
 538                 cand = nd;
 539         }
 540         if (cand)
 541                 sbuild_id = strdup(cand->s);
 542         strlist__delete(bidlist);
 543
 544         return sbuild_id;
 545 }
 546
 547 char *build_id_cache__cachedir(const char *sbuild_id, const char *name,
 548                                struct nsinfo *nsi, bool is_kallsyms,
 549                                bool is_vdso)
 550 {
 551         char *realname = (char *)name, *filename;
 552         bool slash = is_kallsyms || is_vdso;
 553
 554         if (!slash) {
 555                 realname = nsinfo__realpath(name, nsi);
 556                 if (!realname)
 557                         return NULL;
 558         }
 559
 560         if (asprintf(&filename, "%s%s%s%s%s", buildid_dir, slash ? "/" : "",
 561                      is_vdso ? DSO__NAME_VDSO : realname,
 562                      sbuild_id ? "/" : "", sbuild_id ?: "") < 0)
 563                 filename = NULL;
 564
 565         if (!slash)
 566                 free(realname);
 567
 568         return filename;
 569 }
 570
 571 int build_id_cache__list_build_ids(const char *pathname, struct nsinfo *nsi,
 572                                    struct strlist **result)
 573 {
 574         char *dir_name;
 575         int ret = 0;
 576
 577         dir_name = build_id_cache__cachedir(NULL, pathname, nsi, false, false);
 578         if (!dir_name)
 579                 return -ENOMEM;
 580
 581         *result = lsdir(dir_name, lsdir_no_dot_filter);
 582         if (!*result)
 583                 ret = -errno;
 584         free(dir_name);
 585
 586         return ret;
 587 }
 588
 589 #if defined(HAVE_LIBELF_SUPPORT) && defined(HAVE_GELF_GETNOTE_SUPPORT)
 590 static int build_id_cache__add_sdt_cache(const char *sbuild_id,
 591                                           const char *realname,
 592                                           struct nsinfo *nsi)
 593 {
 594         struct probe_cache *cache;
 595         int ret;
 596         struct nscookie nsc;
 597
 598         cache = probe_cache__new(sbuild_id, nsi);
 599         if (!cache)
 600                 return -1;
 601
 602         nsinfo__mountns_enter(nsi, &nsc);
 603         ret = probe_cache__scan_sdt(cache, realname);
 604         nsinfo__mountns_exit(&nsc);
 605         if (ret >= 0) {
 606                 pr_debug4("Found %d SDTs in %s\n", ret, realname);
 607                 if (probe_cache__commit(cache) < 0)
 608                         ret = -1;
 609         }
 610         probe_cache__delete(cache);
 611         return ret;
 612 }
 613 #else
 614 #define build_id_cache__add_sdt_cache(sbuild_id, realname, nsi) (0)
 615 #endif
 616
 617 static char *build_id_cache__find_debug(const char *sbuild_id,
 618                                         struct nsinfo *nsi)
 619 {
 620         char *realname = NULL;
 621         char *debugfile;
 622         struct nscookie nsc;
 623         size_t len = 0;
 624
 625         debugfile = calloc(1, PATH_MAX);
 626         if (!debugfile)
 627                 goto out;
 628
 629         len = __symbol__join_symfs(debugfile, PATH_MAX,
 630                                    "/usr/lib/debug/.build-id/");
 631         snprintf(debugfile + len, PATH_MAX - len, "%.2s/%s.debug", sbuild_id,
 632                  sbuild_id + 2);
 633
 634         nsinfo__mountns_enter(nsi, &nsc);
 635         realname = realpath(debugfile, NULL);
 636         if (realname && access(realname, R_OK))
 637                 zfree(&realname);
 638         nsinfo__mountns_exit(&nsc);
 639 out:
 640         free(debugfile);
 641         return realname;
 642 }
 643
 644 int build_id_cache__add_s(const char *sbuild_id, const char *name,
 645                           struct nsinfo *nsi, bool is_kallsyms, bool is_vdso)
 646 {
 647         const size_t size = PATH_MAX;
 648         char *realname = NULL, *filename = NULL, *dir_name = NULL,
 649              *linkname = zalloc(size), *tmp;
 650         char *debugfile = NULL;
 651         int err = -1;
 652
 653         if (!is_kallsyms) {
 654                 if (!is_vdso)
 655                         realname = nsinfo__realpath(name, nsi);
 656                 else
 657                         realname = realpath(name, NULL);
 658                 if (!realname)
 659                         goto out_free;
 660         }
 661
 662         dir_name = build_id_cache__cachedir(sbuild_id, name, nsi, is_kallsyms,
 663                                             is_vdso);
 664         if (!dir_name)
 665                 goto out_free;
 666
 667         /* Remove old style build-id cache */
 668         if (is_regular_file(dir_name))
 669                 if (unlink(dir_name))
 670                         goto out_free;
 671
 672         if (mkdir_p(dir_name, 0755))
 673                 goto out_free;
 674
 675         /* Save the allocated buildid dirname */
 676         if (asprintf(&filename, "%s/%s", dir_name,
 677                      build_id_cache__basename(is_kallsyms, is_vdso,
 678                      false)) < 0) {
 679                 filename = NULL;
 680                 goto out_free;
 681         }
 682
 683         if (access(filename, F_OK)) {
 684                 if (is_kallsyms) {
 685                         if (copyfile("/proc/kallsyms", filename))
 686                                 goto out_free;
 687                 } else if (nsi && nsi->need_setns) {
 688                         if (copyfile_ns(name, filename, nsi))
 689                                 goto out_free;
 690                 } else if (link(realname, filename) && errno != EEXIST &&
 691                                 copyfile(name, filename))
 692                         goto out_free;
 693         }
 694
 695         /* Some binaries are stripped, but have .debug files with their symbol
 696          * table.  Check to see if we can locate one of those, since the elf
 697          * file itself may not be very useful to users of our tools without a
 698          * symtab.
 699          */
 700         if (!is_kallsyms && !is_vdso &&
 701             strncmp(".ko", name + strlen(name) - 3, 3)) {
 702                 debugfile = build_id_cache__find_debug(sbuild_id, nsi);
 703                 if (debugfile) {
 704                         zfree(&filename);
 705                         if (asprintf(&filename, "%s/%s", dir_name,
 706                             build_id_cache__basename(false, false, true)) < 0) {
 707                                 filename = NULL;
 708                                 goto out_free;
 709                         }
 710                         if (access(filename, F_OK)) {
 711                                 if (nsi && nsi->need_setns) {
 712                                         if (copyfile_ns(debugfile, filename,
 713                                                         nsi))
 714                                                 goto out_free;
 715                                 } else if (link(debugfile, filename) &&
 716                                                 errno != EEXIST &&
 717                                                 copyfile(debugfile, filename))
 718                                         goto out_free;
 719                         }
 720                 }
 721         }
 722
 723         if (!build_id_cache__linkname(sbuild_id, linkname, size))
 724                 goto out_free;
 725         tmp = strrchr(linkname, '/');
 726         *tmp = '\0';
 727
 728         if (access(linkname, X_OK) && mkdir_p(linkname, 0755))
 729                 goto out_free;
 730
 731         *tmp = '/';
 732         tmp = dir_name + strlen(buildid_dir) - 5;
 733         memcpy(tmp, "../..", 5);
 734
 735         if (symlink(tmp, linkname) == 0)
 736                 err = 0;
 737
 738         /* Update SDT cache : error is just warned */
 739         if (realname &&
 740             build_id_cache__add_sdt_cache(sbuild_id, realname, nsi) < 0)
 741                 pr_debug4("Failed to update/scan SDT cache for %s\n", realname);
 742
 743 out_free:
 744         if (!is_kallsyms)
 745                 free(realname);
 746         free(filename);
 747         free(debugfile);
 748         free(dir_name);
 749         free(linkname);
 750         return err;
 751 }
 752
 753 static int build_id_cache__add_b(const u8 *build_id, size_t build_id_size,
 754                                  const char *name, struct nsinfo *nsi,
 755                                  bool is_kallsyms, bool is_vdso)
 756 {
 757         char sbuild_id[SBUILD_ID_SIZE];
 758
 759         build_id__sprintf(build_id, build_id_size, sbuild_id);
 760
 761         return build_id_cache__add_s(sbuild_id, name, nsi, is_kallsyms,
 762                                      is_vdso);
 763 }
 764
 765 bool build_id_cache__cached(const char *sbuild_id)
 766 {
 767         bool ret = false;
 768         char *filename = build_id_cache__linkname(sbuild_id, NULL, 0);
 769
 770         if (filename && !access(filename, F_OK))
 771                 ret = true;
 772         free(filename);
 773
 774         return ret;
 775 }
 776
 777 int build_id_cache__remove_s(const char *sbuild_id)
 778 {
 779         const size_t size = PATH_MAX;
 780         char *filename = zalloc(size),
 781              *linkname = zalloc(size), *tmp;
 782         int err = -1;
 783
 784         if (filename == NULL || linkname == NULL)
 785                 goto out_free;
 786
 787         if (!build_id_cache__linkname(sbuild_id, linkname, size))
 788                 goto out_free;
 789
 790         if (access(linkname, F_OK))
 791                 goto out_free;
 792
 793         if (readlink(linkname, filename, size - 1) < 0)
 794                 goto out_free;
 795
 796         if (unlink(linkname))
 797                 goto out_free;
 798
 799         /*
 800          * Since the link is relative, we must make it absolute:
 801          */
 802         tmp = strrchr(linkname, '/') + 1;
 803         snprintf(tmp, size - (tmp - linkname), "%s", filename);
 804
 805         if (rm_rf(linkname))
 806                 goto out_free;
 807
 808         err = 0;
 809 out_free:
 810         free(filename);
 811         free(linkname);
 812         return err;
 813 }
 814
 815 static int dso__cache_build_id(struct dso *dso, struct machine *machine)
 816 {
 817         bool is_kallsyms = dso__is_kallsyms(dso);
 818         bool is_vdso = dso__is_vdso(dso);
 819         const char *name = dso->long_name;
 820
 821         if (dso__is_kcore(dso)) {
 822                 is_kallsyms = true;
 823                 name = machine->mmap_name;
 824         }
 825         return build_id_cache__add_b(dso->build_id, sizeof(dso->build_id), name,
 826                                      dso->nsinfo, is_kallsyms, is_vdso);
 827 }
 828
 829 static int __dsos__cache_build_ids(struct list_head *head,
 830                                    struct machine *machine)
 831 {
 832         struct dso *pos;
 833         int err = 0;
 834
 835         dsos__for_each_with_build_id(pos, head)
 836                 if (dso__cache_build_id(pos, machine))
 837                         err = -1;
 838
 839         return err;
 840 }
 841
 842 static int machine__cache_build_ids(struct machine *machine)
 843 {
 844         return __dsos__cache_build_ids(&machine->dsos.head, machine);
 845 }
 846
 847 int perf_session__cache_build_ids(struct perf_session *session)
 848 {
 849         struct rb_node *nd;
 850         int ret;
 851
 852         if (no_buildid_cache)
 853                 return 0;
 854
 855         if (mkdir(buildid_dir, 0755) != 0 && errno != EEXIST)
 856                 return -1;
 857
 858         ret = machine__cache_build_ids(&session->machines.host);
 859
 860         for (nd = rb_first_cached(&session->machines.guests); nd;
 861              nd = rb_next(nd)) {
 862                 struct machine *pos = rb_entry(nd, struct machine, rb_node);
 863                 ret |= machine__cache_build_ids(pos);
 864         }
 865         return ret ? -1 : 0;
 866 }
 867
 868 static bool machine__read_build_ids(struct machine *machine, bool with_hits)
 869 {
 870         return __dsos__read_build_ids(&machine->dsos.head, with_hits);
 871 }
 872
 873 bool perf_session__read_build_ids(struct perf_session *session, bool with_hits)
 874 {
 875         struct rb_node *nd;
 876         bool ret = machine__read_build_ids(&session->machines.host, with_hits);
 877
 878         for (nd = rb_first_cached(&session->machines.guests); nd;
 879              nd = rb_next(nd)) {
 880                 struct machine *pos = rb_entry(nd, struct machine, rb_node);
 881                 ret |= machine__read_build_ids(pos, with_hits);
 882         }
 883
 884         return ret;
 885 }