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