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 #ifdef HAVE_DEBUGINFOD_SUPPORT
  35 #include <elfutils/debuginfod.h>
  36 #endif
  37
  38 #include <linux/ctype.h>
  39 #include <linux/zalloc.h>
  40
  41 static bool no_buildid_cache;
  42
  43 int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
  44                            union perf_event *event,
  45                            struct perf_sample *sample,
  46                            struct evsel *evsel __maybe_unused,
  47                            struct machine *machine)
  48 {
  49         struct addr_location al;
  50         struct thread *thread = machine__findnew_thread(machine, sample->pid,
  51                                                         sample->tid);
  52
  53         if (thread == NULL) {
  54                 pr_err("problem processing %d event, skipping it.\n",
  55                         event->header.type);
  56                 return -1;
  57         }
  58
  59         if (thread__find_map(thread, sample->cpumode, sample->ip, &al))
  60                 al.map->dso->hit = 1;
  61
  62         thread__put(thread);
  63         return 0;
  64 }
  65
  66 static int perf_event__exit_del_thread(struct perf_tool *tool __maybe_unused,
  67                                        union perf_event *event,
  68                                        struct perf_sample *sample
  69                                        __maybe_unused,
  70                                        struct machine *machine)
  71 {
  72         struct thread *thread = machine__findnew_thread(machine,
  73                                                         event->fork.pid,
  74                                                         event->fork.tid);
  75
  76         dump_printf("(%d:%d):(%d:%d)\n", event->fork.pid, event->fork.tid,
  77                     event->fork.ppid, event->fork.ptid);
  78
  79         if (thread) {
  80                 machine__remove_thread(machine, thread);
  81                 thread__put(thread);
  82         }
  83
  84         return 0;
  85 }
  86
  87 struct perf_tool build_id__mark_dso_hit_ops = {
  88         .sample = build_id__mark_dso_hit,
  89         .mmap   = perf_event__process_mmap,
  90         .mmap2  = perf_event__process_mmap2,
  91         .fork   = perf_event__process_fork,
  92         .exit   = perf_event__exit_del_thread,
  93         .attr            = perf_event__process_attr,
  94         .build_id        = perf_event__process_build_id,
  95         .ordered_events  = true,
  96 };
  97
  98 int build_id__sprintf(const u8 *build_id, int len, char *bf)
  99 {
 100         char *bid = bf;
 101         const u8 *raw = build_id;
 102         int i;
 103
 104         for (i = 0; i < len; ++i) {
 105                 sprintf(bid, "%02x", *raw);
 106                 ++raw;
 107                 bid += 2;
 108         }
 109
 110         return (bid - bf) + 1;
 111 }
 112
 113 int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id)
 114 {
 115         char notes[PATH_MAX];
 116         u8 build_id[BUILD_ID_SIZE];
 117         int ret;
 118
 119         if (!root_dir)
 120                 root_dir = "";
 121
 122         scnprintf(notes, sizeof(notes), "%s/sys/kernel/notes", root_dir);
 123
 124         ret = sysfs__read_build_id(notes, build_id, sizeof(build_id));
 125         if (ret < 0)
 126                 return ret;
 127
 128         return build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
 129 }
 130
 131 int filename__sprintf_build_id(const char *pathname, char *sbuild_id)
 132 {
 133         u8 build_id[BUILD_ID_SIZE];
 134         int ret;
 135
 136         ret = filename__read_build_id(pathname, build_id, sizeof(build_id));
 137         if (ret < 0)
 138                 return ret;
 139         else if (ret != sizeof(build_id))
 140                 return -EINVAL;
 141
 142         return build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
 143 }
 144
 145 /* asnprintf consolidates asprintf and snprintf */
 146 static int asnprintf(char **strp, size_t size, const char *fmt, ...)
 147 {
 148         va_list ap;
 149         int ret;
 150
 151         if (!strp)
 152                 return -EINVAL;
 153
 154         va_start(ap, fmt);
 155         if (*strp)
 156                 ret = vsnprintf(*strp, size, fmt, ap);
 157         else
 158                 ret = vasprintf(strp, fmt, ap);
 159         va_end(ap);
 160
 161         return ret;
 162 }
 163
 164 char *build_id_cache__kallsyms_path(const char *sbuild_id, char *bf,
 165                                     size_t size)
 166 {
 167         bool retry_old = true;
 168
 169         snprintf(bf, size, "%s/%s/%s/kallsyms",
 170                  buildid_dir, DSO__NAME_KALLSYMS, sbuild_id);
 171 retry:
 172         if (!access(bf, F_OK))
 173                 return bf;
 174         if (retry_old) {
 175                 /* Try old style kallsyms cache */
 176                 snprintf(bf, size, "%s/%s/%s",
 177                          buildid_dir, DSO__NAME_KALLSYMS, sbuild_id);
 178                 retry_old = false;
 179                 goto retry;
 180         }
 181
 182         return NULL;
 183 }
 184
 185 char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size)
 186 {
 187         char *tmp = bf;
 188         int ret = asnprintf(&bf, size, "%s/.build-id/%.2s/%s", buildid_dir,
 189                             sbuild_id, sbuild_id + 2);
 190         if (ret < 0 || (tmp && size < (unsigned int)ret))
 191                 return NULL;
 192         return bf;
 193 }
 194
 195 /* The caller is responsible to free the returned buffer. */
 196 char *build_id_cache__origname(const char *sbuild_id)
 197 {
 198         char *linkname;
 199         char buf[PATH_MAX];
 200         char *ret = NULL, *p;
 201         size_t offs = 5;        /* == strlen("../..") */
 202         ssize_t len;
 203
 204         linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
 205         if (!linkname)
 206                 return NULL;
 207
 208         len = readlink(linkname, buf, sizeof(buf) - 1);
 209         if (len <= 0)
 210                 goto out;
 211         buf[len] = '\0';
 212
 213         /* The link should be "../..<origpath>/<sbuild_id>" */
 214         p = strrchr(buf, '/');  /* Cut off the "/<sbuild_id>" */
 215         if (p && (p > buf + offs)) {
 216                 *p = '\0';
 217                 if (buf[offs + 1] == '[')
 218                         offs++; /*
 219                                  * This is a DSO name, like [kernel.kallsyms].
 220                                  * Skip the first '/', since this is not the
 221                                  * cache of a regular file.
 222                                  */
 223                 ret = strdup(buf + offs);       /* Skip "../..[/]" */
 224         }
 225 out:
 226         free(linkname);
 227         return ret;
 228 }
 229
 230 /* Check if the given build_id cache is valid on current running system */
 231 static bool build_id_cache__valid_id(char *sbuild_id)
 232 {
 233         char real_sbuild_id[SBUILD_ID_SIZE] = "";
 234         char *pathname;
 235         int ret = 0;
 236         bool result = false;
 237
 238         pathname = build_id_cache__origname(sbuild_id);
 239         if (!pathname)
 240                 return false;
 241
 242         if (!strcmp(pathname, DSO__NAME_KALLSYMS))
 243                 ret = sysfs__sprintf_build_id("/", real_sbuild_id);
 244         else if (pathname[0] == '/')
 245                 ret = filename__sprintf_build_id(pathname, real_sbuild_id);
 246         else
 247                 ret = -EINVAL;  /* Should we support other special DSO cache? */
 248         if (ret >= 0)
 249                 result = (strcmp(sbuild_id, real_sbuild_id) == 0);
 250         free(pathname);
 251
 252         return result;
 253 }
 254
 255 static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso,
 256                                             bool is_debug)
 257 {
 258         return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : (is_debug ?
 259             "debug" : "elf"));
 260 }
 261
 262 char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
 263                              bool is_debug)
 264 {
 265         bool is_kallsyms = dso__is_kallsyms((struct dso *)dso);
 266         bool is_vdso = dso__is_vdso((struct dso *)dso);
 267         char sbuild_id[SBUILD_ID_SIZE];
 268         char *linkname;
 269         bool alloc = (bf == NULL);
 270         int ret;
 271
 272         if (!dso->has_build_id)
 273                 return NULL;
 274
 275         build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);
 276         linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
 277         if (!linkname)
 278                 return NULL;
 279
 280         /* Check if old style build_id cache */
 281         if (is_regular_file(linkname))
 282                 ret = asnprintf(&bf, size, "%s", linkname);
 283         else
 284                 ret = asnprintf(&bf, size, "%s/%s", linkname,
 285                          build_id_cache__basename(is_kallsyms, is_vdso,
 286                                                   is_debug));
 287         if (ret < 0 || (!alloc && size < (unsigned int)ret))
 288                 bf = NULL;
 289         free(linkname);
 290
 291         return bf;
 292 }
 293
 294 #define dsos__for_each_with_build_id(pos, head) \
 295         list_for_each_entry(pos, head, node)    \
 296                 if (!pos->has_build_id)         \
 297                         continue;               \
 298                 else
 299
 300 static int write_buildid(const char *name, size_t name_len, u8 *build_id,
 301                          pid_t pid, u16 misc, struct feat_fd *fd)
 302 {
 303         int err;
 304         struct perf_record_header_build_id b;
 305         size_t len;
 306
 307         len = name_len + 1;
 308         len = PERF_ALIGN(len, NAME_ALIGN);
 309
 310         memset(&b, 0, sizeof(b));
 311         memcpy(&b.build_id, build_id, BUILD_ID_SIZE);
 312         b.pid = pid;
 313         b.header.misc = misc;
 314         b.header.size = sizeof(b) + len;
 315
 316         err = do_write(fd, &b, sizeof(b));
 317         if (err < 0)
 318                 return err;
 319
 320         return write_padded(fd, name, name_len + 1, len);
 321 }
 322
 323 static int machine__write_buildid_table(struct machine *machine,
 324                                         struct feat_fd *fd)
 325 {
 326         int err = 0;
 327         struct dso *pos;
 328         u16 kmisc = PERF_RECORD_MISC_KERNEL,
 329             umisc = PERF_RECORD_MISC_USER;
 330
 331         if (!machine__is_host(machine)) {
 332                 kmisc = PERF_RECORD_MISC_GUEST_KERNEL;
 333                 umisc = PERF_RECORD_MISC_GUEST_USER;
 334         }
 335
 336         dsos__for_each_with_build_id(pos, &machine->dsos.head) {
 337                 const char *name;
 338                 size_t name_len;
 339                 bool in_kernel = false;
 340
 341                 if (!pos->hit && !dso__is_vdso(pos))
 342                         continue;
 343
 344                 if (dso__is_vdso(pos)) {
 345                         name = pos->short_name;
 346                         name_len = pos->short_name_len;
 347                 } else if (dso__is_kcore(pos)) {
 348                         name = machine->mmap_name;
 349                         name_len = strlen(name);
 350                 } else {
 351                         name = pos->long_name;
 352                         name_len = pos->long_name_len;
 353                 }
 354
 355                 in_kernel = pos->kernel ||
 356                                 is_kernel_module(name,
 357                                         PERF_RECORD_MISC_CPUMODE_UNKNOWN);
 358                 err = write_buildid(name, name_len, pos->build_id, machine->pid,
 359                                     in_kernel ? kmisc : umisc, fd);
 360                 if (err)
 361                         break;
 362         }
 363
 364         return err;
 365 }
 366
 367 int perf_session__write_buildid_table(struct perf_session *session,
 368                                       struct feat_fd *fd)
 369 {
 370         struct rb_node *nd;
 371         int err = machine__write_buildid_table(&session->machines.host, fd);
 372
 373         if (err)
 374                 return err;
 375
 376         for (nd = rb_first_cached(&session->machines.guests); nd;
 377              nd = rb_next(nd)) {
 378                 struct machine *pos = rb_entry(nd, struct machine, rb_node);
 379                 err = machine__write_buildid_table(pos, fd);
 380                 if (err)
 381                         break;
 382         }
 383         return err;
 384 }
 385
 386 static int __dsos__hit_all(struct list_head *head)
 387 {
 388         struct dso *pos;
 389
 390         list_for_each_entry(pos, head, node)
 391                 pos->hit = true;
 392
 393         return 0;
 394 }
 395
 396 static int machine__hit_all_dsos(struct machine *machine)
 397 {
 398         return __dsos__hit_all(&machine->dsos.head);
 399 }
 400
 401 int dsos__hit_all(struct perf_session *session)
 402 {
 403         struct rb_node *nd;
 404         int err;
 405
 406         err = machine__hit_all_dsos(&session->machines.host);
 407         if (err)
 408                 return err;
 409
 410         for (nd = rb_first_cached(&session->machines.guests); nd;
 411              nd = rb_next(nd)) {
 412                 struct machine *pos = rb_entry(nd, struct machine, rb_node);
 413
 414                 err = machine__hit_all_dsos(pos);
 415                 if (err)
 416                         return err;
 417         }
 418
 419         return 0;
 420 }
 421
 422 void disable_buildid_cache(void)
 423 {
 424         no_buildid_cache = true;
 425 }
 426
 427 static bool lsdir_bid_head_filter(const char *name __maybe_unused,
 428                                   struct dirent *d)
 429 {
 430         return (strlen(d->d_name) == 2) &&
 431                 isxdigit(d->d_name[0]) && isxdigit(d->d_name[1]);
 432 }
 433
 434 static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
 435                                   struct dirent *d)
 436 {
 437         int i = 0;
 438         while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
 439                 i++;
 440         return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
 441 }
 442
 443 struct strlist *build_id_cache__list_all(bool validonly)
 444 {
 445         struct strlist *toplist, *linklist = NULL, *bidlist;
 446         struct str_node *nd, *nd2;
 447         char *topdir, *linkdir = NULL;
 448         char sbuild_id[SBUILD_ID_SIZE];
 449
 450         /* for filename__ functions */
 451         if (validonly)
 452                 symbol__init(NULL);
 453
 454         /* Open the top-level directory */
 455         if (asprintf(&topdir, "%s/.build-id/", buildid_dir) < 0)
 456                 return NULL;
 457
 458         bidlist = strlist__new(NULL, NULL);
 459         if (!bidlist)
 460                 goto out;
 461
 462         toplist = lsdir(topdir, lsdir_bid_head_filter);
 463         if (!toplist) {
 464                 pr_debug("Error in lsdir(%s): %d\n", topdir, errno);
 465                 /* If there is no buildid cache, return an empty list */
 466                 if (errno == ENOENT)
 467                         goto out;
 468                 goto err_out;
 469         }
 470
 471         strlist__for_each_entry(nd, toplist) {
 472                 if (asprintf(&linkdir, "%s/%s", topdir, nd->s) < 0)
 473                         goto err_out;
 474                 /* Open the lower-level directory */
 475                 linklist = lsdir(linkdir, lsdir_bid_tail_filter);
 476                 if (!linklist) {
 477                         pr_debug("Error in lsdir(%s): %d\n", linkdir, errno);
 478                         goto err_out;
 479                 }
 480                 strlist__for_each_entry(nd2, linklist) {
 481                         if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
 482                                      nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
 483                                 goto err_out;
 484                         if (validonly && !build_id_cache__valid_id(sbuild_id))
 485                                 continue;
 486                         if (strlist__add(bidlist, sbuild_id) < 0)
 487                                 goto err_out;
 488                 }
 489                 strlist__delete(linklist);
 490                 zfree(&linkdir);
 491         }
 492
 493 out_free:
 494         strlist__delete(toplist);
 495 out:
 496         free(topdir);
 497
 498         return bidlist;
 499
 500 err_out:
 501         strlist__delete(linklist);
 502         zfree(&linkdir);
 503         strlist__delete(bidlist);
 504         bidlist = NULL;
 505         goto out_free;
 506 }
 507
 508 static bool str_is_build_id(const char *maybe_sbuild_id, size_t len)
 509 {
 510         size_t i;
 511
 512         for (i = 0; i < len; i++) {
 513                 if (!isxdigit(maybe_sbuild_id[i]))
 514                         return false;
 515         }
 516         return true;
 517 }
 518
 519 /* Return the valid complete build-id */
 520 char *build_id_cache__complement(const char *incomplete_sbuild_id)
 521 {
 522         struct strlist *bidlist;
 523         struct str_node *nd, *cand = NULL;
 524         char *sbuild_id = NULL;
 525         size_t len = strlen(incomplete_sbuild_id);
 526
 527         if (len >= SBUILD_ID_SIZE ||
 528             !str_is_build_id(incomplete_sbuild_id, len))
 529                 return NULL;
 530
 531         bidlist = build_id_cache__list_all(true);
 532         if (!bidlist)
 533                 return NULL;
 534
 535         strlist__for_each_entry(nd, bidlist) {
 536                 if (strncmp(nd->s, incomplete_sbuild_id, len) != 0)
 537                         continue;
 538                 if (cand) {     /* Error: There are more than 2 candidates. */
 539                         cand = NULL;
 540                         break;
 541                 }
 542                 cand = nd;
 543         }
 544         if (cand)
 545                 sbuild_id = strdup(cand->s);
 546         strlist__delete(bidlist);
 547
 548         return sbuild_id;
 549 }
 550
 551 char *build_id_cache__cachedir(const char *sbuild_id, const char *name,
 552                                struct nsinfo *nsi, bool is_kallsyms,
 553                                bool is_vdso)
 554 {
 555         char *realname = (char *)name, *filename;
 556         bool slash = is_kallsyms || is_vdso;
 557
 558         if (!slash) {
 559                 realname = nsinfo__realpath(name, nsi);
 560                 if (!realname)
 561                         return NULL;
 562         }
 563
 564         if (asprintf(&filename, "%s%s%s%s%s", buildid_dir, slash ? "/" : "",
 565                      is_vdso ? DSO__NAME_VDSO : realname,
 566                      sbuild_id ? "/" : "", sbuild_id ?: "") < 0)
 567                 filename = NULL;
 568
 569         if (!slash)
 570                 free(realname);
 571
 572         return filename;
 573 }
 574
 575 int build_id_cache__list_build_ids(const char *pathname, struct nsinfo *nsi,
 576                                    struct strlist **result)
 577 {
 578         char *dir_name;
 579         int ret = 0;
 580
 581         dir_name = build_id_cache__cachedir(NULL, pathname, nsi, false, false);
 582         if (!dir_name)
 583                 return -ENOMEM;
 584
 585         *result = lsdir(dir_name, lsdir_no_dot_filter);
 586         if (!*result)
 587                 ret = -errno;
 588         free(dir_name);
 589
 590         return ret;
 591 }
 592
 593 #if defined(HAVE_LIBELF_SUPPORT) && defined(HAVE_GELF_GETNOTE_SUPPORT)
 594 static int build_id_cache__add_sdt_cache(const char *sbuild_id,
 595                                           const char *realname,
 596                                           struct nsinfo *nsi)
 597 {
 598         struct probe_cache *cache;
 599         int ret;
 600         struct nscookie nsc;
 601
 602         cache = probe_cache__new(sbuild_id, nsi);
 603         if (!cache)
 604                 return -1;
 605
 606         nsinfo__mountns_enter(nsi, &nsc);
 607         ret = probe_cache__scan_sdt(cache, realname);
 608         nsinfo__mountns_exit(&nsc);
 609         if (ret >= 0) {
 610                 pr_debug4("Found %d SDTs in %s\n", ret, realname);
 611                 if (probe_cache__commit(cache) < 0)
 612                         ret = -1;
 613         }
 614         probe_cache__delete(cache);
 615         return ret;
 616 }
 617 #else
 618 #define build_id_cache__add_sdt_cache(sbuild_id, realname, nsi) (0)
 619 #endif
 620
 621 static char *build_id_cache__find_debug(const char *sbuild_id,
 622                                         struct nsinfo *nsi)
 623 {
 624         char *realname = NULL;
 625         char *debugfile;
 626         struct nscookie nsc;
 627         size_t len = 0;
 628
 629         debugfile = calloc(1, PATH_MAX);
 630         if (!debugfile)
 631                 goto out;
 632
 633         len = __symbol__join_symfs(debugfile, PATH_MAX,
 634                                    "/usr/lib/debug/.build-id/");
 635         snprintf(debugfile + len, PATH_MAX - len, "%.2s/%s.debug", sbuild_id,
 636                  sbuild_id + 2);
 637
 638         nsinfo__mountns_enter(nsi, &nsc);
 639         realname = realpath(debugfile, NULL);
 640         if (realname && access(realname, R_OK))
 641                 zfree(&realname);
 642         nsinfo__mountns_exit(&nsc);
 643
 644 #ifdef HAVE_DEBUGINFOD_SUPPORT
 645         if (realname == NULL) {
 646                 debuginfod_client* c = debuginfod_begin();
 647                 if (c != NULL) {
 648                         int fd = debuginfod_find_debuginfo(c,
 649                                                            (const unsigned char*)sbuild_id, 0,
 650                                                            &realname);
 651                         if (fd >= 0)
 652                                 close(fd); /* retaining reference by realname */
 653                         debuginfod_end(c);
 654                 }
 655         }
 656 #endif
 657
 658 out:
 659         free(debugfile);
 660         return realname;
 661 }
 662
 663 int build_id_cache__add_s(const char *sbuild_id, const char *name,
 664                           struct nsinfo *nsi, bool is_kallsyms, bool is_vdso)
 665 {
 666         const size_t size = PATH_MAX;
 667         char *realname = NULL, *filename = NULL, *dir_name = NULL,
 668              *linkname = zalloc(size), *tmp;
 669         char *debugfile = NULL;
 670         int err = -1;
 671
 672         if (!is_kallsyms) {
 673                 if (!is_vdso)
 674                         realname = nsinfo__realpath(name, nsi);
 675                 else
 676                         realname = realpath(name, NULL);
 677                 if (!realname)
 678                         goto out_free;
 679         }
 680
 681         dir_name = build_id_cache__cachedir(sbuild_id, name, nsi, is_kallsyms,
 682                                             is_vdso);
 683         if (!dir_name)
 684                 goto out_free;
 685
 686         /* Remove old style build-id cache */
 687         if (is_regular_file(dir_name))
 688                 if (unlink(dir_name))
 689                         goto out_free;
 690
 691         if (mkdir_p(dir_name, 0755))
 692                 goto out_free;
 693
 694         /* Save the allocated buildid dirname */
 695         if (asprintf(&filename, "%s/%s", dir_name,
 696                      build_id_cache__basename(is_kallsyms, is_vdso,
 697                      false)) < 0) {
 698                 filename = NULL;
 699                 goto out_free;
 700         }
 701
 702         if (access(filename, F_OK)) {
 703                 if (is_kallsyms) {
 704                         if (copyfile("/proc/kallsyms", filename))
 705                                 goto out_free;
 706                 } else if (nsi && nsi->need_setns) {
 707                         if (copyfile_ns(name, filename, nsi))
 708                                 goto out_free;
 709                 } else if (link(realname, filename) && errno != EEXIST &&
 710                                 copyfile(name, filename))
 711                         goto out_free;
 712         }
 713
 714         /* Some binaries are stripped, but have .debug files with their symbol
 715          * table.  Check to see if we can locate one of those, since the elf
 716          * file itself may not be very useful to users of our tools without a
 717          * symtab.
 718          */
 719         if (!is_kallsyms && !is_vdso &&
 720             strncmp(".ko", name + strlen(name) - 3, 3)) {
 721                 debugfile = build_id_cache__find_debug(sbuild_id, nsi);
 722                 if (debugfile) {
 723                         zfree(&filename);
 724                         if (asprintf(&filename, "%s/%s", dir_name,
 725                             build_id_cache__basename(false, false, true)) < 0) {
 726                                 filename = NULL;
 727                                 goto out_free;
 728                         }
 729                         if (access(filename, F_OK)) {
 730                                 if (nsi && nsi->need_setns) {
 731                                         if (copyfile_ns(debugfile, filename,
 732                                                         nsi))
 733                                                 goto out_free;
 734                                 } else if (link(debugfile, filename) &&
 735                                                 errno != EEXIST &&
 736                                                 copyfile(debugfile, filename))
 737                                         goto out_free;
 738                         }
 739                 }
 740         }
 741
 742         if (!build_id_cache__linkname(sbuild_id, linkname, size))
 743                 goto out_free;
 744         tmp = strrchr(linkname, '/');
 745         *tmp = '\0';
 746
 747         if (access(linkname, X_OK) && mkdir_p(linkname, 0755))
 748                 goto out_free;
 749
 750         *tmp = '/';
 751         tmp = dir_name + strlen(buildid_dir) - 5;
 752         memcpy(tmp, "../..", 5);
 753
 754         if (symlink(tmp, linkname) == 0)
 755                 err = 0;
 756
 757         /* Update SDT cache : error is just warned */
 758         if (realname &&
 759             build_id_cache__add_sdt_cache(sbuild_id, realname, nsi) < 0)
 760                 pr_debug4("Failed to update/scan SDT cache for %s\n", realname);
 761
 762 out_free:
 763         if (!is_kallsyms)
 764                 free(realname);
 765         free(filename);
 766         free(debugfile);
 767         free(dir_name);
 768         free(linkname);
 769         return err;
 770 }
 771
 772 static int build_id_cache__add_b(const u8 *build_id, size_t build_id_size,
 773                                  const char *name, struct nsinfo *nsi,
 774                                  bool is_kallsyms, bool is_vdso)
 775 {
 776         char sbuild_id[SBUILD_ID_SIZE];
 777
 778         build_id__sprintf(build_id, build_id_size, sbuild_id);
 779
 780         return build_id_cache__add_s(sbuild_id, name, nsi, is_kallsyms,
 781                                      is_vdso);
 782 }
 783
 784 bool build_id_cache__cached(const char *sbuild_id)
 785 {
 786         bool ret = false;
 787         char *filename = build_id_cache__linkname(sbuild_id, NULL, 0);
 788
 789         if (filename && !access(filename, F_OK))
 790                 ret = true;
 791         free(filename);
 792
 793         return ret;
 794 }
 795
 796 int build_id_cache__remove_s(const char *sbuild_id)
 797 {
 798         const size_t size = PATH_MAX;
 799         char *filename = zalloc(size),
 800              *linkname = zalloc(size), *tmp;
 801         int err = -1;
 802
 803         if (filename == NULL || linkname == NULL)
 804                 goto out_free;
 805
 806         if (!build_id_cache__linkname(sbuild_id, linkname, size))
 807                 goto out_free;
 808
 809         if (access(linkname, F_OK))
 810                 goto out_free;
 811
 812         if (readlink(linkname, filename, size - 1) < 0)
 813                 goto out_free;
 814
 815         if (unlink(linkname))
 816                 goto out_free;
 817
 818         /*
 819          * Since the link is relative, we must make it absolute:
 820          */
 821         tmp = strrchr(linkname, '/') + 1;
 822         snprintf(tmp, size - (tmp - linkname), "%s", filename);
 823
 824         if (rm_rf(linkname))
 825                 goto out_free;
 826
 827         err = 0;
 828 out_free:
 829         free(filename);
 830         free(linkname);
 831         return err;
 832 }
 833
 834 static int dso__cache_build_id(struct dso *dso, struct machine *machine)
 835 {
 836         bool is_kallsyms = dso__is_kallsyms(dso);
 837         bool is_vdso = dso__is_vdso(dso);
 838         const char *name = dso->long_name;
 839
 840         if (dso__is_kcore(dso)) {
 841                 is_kallsyms = true;
 842                 name = machine->mmap_name;
 843         }
 844         return build_id_cache__add_b(dso->build_id, sizeof(dso->build_id), name,
 845                                      dso->nsinfo, is_kallsyms, is_vdso);
 846 }
 847
 848 static int __dsos__cache_build_ids(struct list_head *head,
 849                                    struct machine *machine)
 850 {
 851         struct dso *pos;
 852         int err = 0;
 853
 854         dsos__for_each_with_build_id(pos, head)
 855                 if (dso__cache_build_id(pos, machine))
 856                         err = -1;
 857
 858         return err;
 859 }
 860
 861 static int machine__cache_build_ids(struct machine *machine)
 862 {
 863         return __dsos__cache_build_ids(&machine->dsos.head, machine);
 864 }
 865
 866 int perf_session__cache_build_ids(struct perf_session *session)
 867 {
 868         struct rb_node *nd;
 869         int ret;
 870
 871         if (no_buildid_cache)
 872                 return 0;
 873
 874         if (mkdir(buildid_dir, 0755) != 0 && errno != EEXIST)
 875                 return -1;
 876
 877         ret = machine__cache_build_ids(&session->machines.host);
 878
 879         for (nd = rb_first_cached(&session->machines.guests); nd;
 880              nd = rb_next(nd)) {
 881                 struct machine *pos = rb_entry(nd, struct machine, rb_node);
 882                 ret |= machine__cache_build_ids(pos);
 883         }
 884         return ret ? -1 : 0;
 885 }
 886
 887 static bool machine__read_build_ids(struct machine *machine, bool with_hits)
 888 {
 889         return __dsos__read_build_ids(&machine->dsos.head, with_hits);
 890 }
 891
 892 bool perf_session__read_build_ids(struct perf_session *session, bool with_hits)
 893 {
 894         struct rb_node *nd;
 895         bool ret = machine__read_build_ids(&session->machines.host, with_hits);
 896
 897         for (nd = rb_first_cached(&session->machines.guests); nd;
 898              nd = rb_next(nd)) {
 899                 struct machine *pos = rb_entry(nd, struct machine, rb_node);
 900                 ret |= machine__read_build_ids(pos, with_hits);
 901         }
 902
 903         return ret;
 904 }