xref: /openbmc/linux/tools/perf/util/build-id.c (revision e0d07278)
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 }
905