1 files changed, 400 insertions, 223 deletions

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index e0148b081bdf..fdb35133fde4 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * build-id.c
  *
@@ -6,14 +7,18 @@
  * Copyright (C) 2009, 2010 Red Hat Inc.
  * Copyright (C) 2009, 2010 Arnaldo Carvalho de Melo <acme@redhat.com>
  */
-#include "util.h"
+#include "util.h" // lsdir(), mkdir_p(), rm_rf()
 #include <dirent.h>
 #include <errno.h>
 #include <stdio.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include "util/copyfile.h"
+#include "dso.h"
 #include "build-id.h"
 #include "event.h"
+#include "namespaces.h"
+#include "map.h"
 #include "symbol.h"
 #include "thread.h"
 #include <linux/kernel.h>
@@ -26,14 +31,31 @@
 #include "probe-file.h"
 #include "strlist.h"
 
-#include "sane_ctype.h"
+#ifdef HAVE_DEBUGINFOD_SUPPORT
+#include <elfutils/debuginfod.h>
+#endif
+
+#include <linux/ctype.h>
+#include <linux/zalloc.h>
+#include <linux/string.h>
+#include <asm/bug.h>
 
 static bool no_buildid_cache;
 
-int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
+static int mark_dso_hit_callback(struct callchain_cursor_node *node, void *data __maybe_unused)
+{
+	struct map *map = node->ms.map;
+
+	if (map)
+		dso__set_hit(map__dso(map));
+
+	return 0;
+}
+
+int build_id__mark_dso_hit(const struct perf_tool *tool __maybe_unused,
 			   union perf_event *event,
 			   struct perf_sample *sample,
-			   struct perf_evsel *evsel __maybe_unused,
+			   struct evsel *evsel,
 			   struct machine *machine)
 {
 	struct addr_location al;
@@ -46,66 +68,41 @@ int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
 		return -1;
 	}
 
-	thread__find_addr_map(thread, sample->cpumode, MAP__FUNCTION, sample->ip, &al);
-
-	if (al.map != NULL)
-		al.map->dso->hit = 1;
-
-	thread__put(thread);
-	return 0;
-}
+	addr_location__init(&al);
+	if (thread__find_map(thread, sample->cpumode, sample->ip, &al))
+		dso__set_hit(map__dso(al.map));
 
-static int perf_event__exit_del_thread(struct perf_tool *tool __maybe_unused,
-				       union perf_event *event,
-				       struct perf_sample *sample
-				       __maybe_unused,
-				       struct machine *machine)
-{
-	struct thread *thread = machine__findnew_thread(machine,
-							event->fork.pid,
-							event->fork.tid);
+	addr_location__exit(&al);
 
-	dump_printf("(%d:%d):(%d:%d)\n", event->fork.pid, event->fork.tid,
-		    event->fork.ppid, event->fork.ptid);
+	sample__for_each_callchain_node(thread, evsel, sample, PERF_MAX_STACK_DEPTH,
+					/*symbols=*/false, mark_dso_hit_callback, /*data=*/NULL);
 
-	if (thread) {
-		machine__remove_thread(machine, thread);
-		thread__put(thread);
-	}
 
+	thread__put(thread);
 	return 0;
 }
 
-struct perf_tool build_id__mark_dso_hit_ops = {
-	.sample	= build_id__mark_dso_hit,
-	.mmap	= perf_event__process_mmap,
-	.mmap2	= perf_event__process_mmap2,
-	.fork	= perf_event__process_fork,
-	.exit	= perf_event__exit_del_thread,
-	.attr		 = perf_event__process_attr,
-	.build_id	 = perf_event__process_build_id,
-	.ordered_events	 = true,
-};
-
-int build_id__sprintf(const u8 *build_id, int len, char *bf)
+int build_id__snprintf(const struct build_id *build_id, char *bf, size_t bf_size)
 {
-	char *bid = bf;
-	const u8 *raw = build_id;
-	int i;
+	size_t offs = 0;
 
-	for (i = 0; i < len; ++i) {
-		sprintf(bid, "%02x", *raw);
-		++raw;
-		bid += 2;
+	if (build_id->size == 0) {
+		/* Ensure bf is always \0 terminated. */
+		if (bf_size > 0)
+			bf[0] = '\0';
+		return 0;
 	}
 
-	return (bid - bf) + 1;
+	for (size_t i = 0; i < build_id->size && offs < bf_size; ++i)
+		offs += snprintf(bf + offs, bf_size - offs, "%02x", build_id->data[i]);
+
+	return offs;
 }
 
-int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id)
+int sysfs__snprintf_build_id(const char *root_dir, char *sbuild_id, size_t sbuild_id_size)
 {
 	char notes[PATH_MAX];
-	u8 build_id[BUILD_ID_SIZE];
+	struct build_id bid = { .size = 0, };
 	int ret;
 
 	if (!root_dir)
@@ -113,25 +110,23 @@ int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id)
 
 	scnprintf(notes, sizeof(notes), "%s/sys/kernel/notes", root_dir);
 
-	ret = sysfs__read_build_id(notes, build_id, sizeof(build_id));
+	ret = sysfs__read_build_id(notes, &bid);
 	if (ret < 0)
 		return ret;
 
-	return build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
+	return build_id__snprintf(&bid, sbuild_id, sbuild_id_size);
 }
 
-int filename__sprintf_build_id(const char *pathname, char *sbuild_id)
+int filename__snprintf_build_id(const char *pathname, char *sbuild_id, size_t sbuild_id_size)
 {
-	u8 build_id[BUILD_ID_SIZE];
+	struct build_id bid = { .size = 0, };
 	int ret;
 
-	ret = filename__read_build_id(pathname, build_id, sizeof(build_id));
+	ret = filename__read_build_id(pathname, &bid);
 	if (ret < 0)
 		return ret;
-	else if (ret != sizeof(build_id))
-		return -EINVAL;
 
-	return build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
+	return build_id__snprintf(&bid, sbuild_id, sbuild_id_size);
 }
 
 /* asnprintf consolidates asprintf and snprintf */
@@ -184,6 +179,7 @@ char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size)
 	return bf;
 }
 
+/* The caller is responsible to free the returned buffer. */
 char *build_id_cache__origname(const char *sbuild_id)
 {
 	char *linkname;
@@ -231,9 +227,9 @@ static bool build_id_cache__valid_id(char *sbuild_id)
 		return false;
 
 	if (!strcmp(pathname, DSO__NAME_KALLSYMS))
-		ret = sysfs__sprintf_build_id("/", real_sbuild_id);
+		ret = sysfs__snprintf_build_id("/", real_sbuild_id, sizeof(real_sbuild_id));
 	else if (pathname[0] == '/')
-		ret = filename__sprintf_build_id(pathname, real_sbuild_id);
+		ret = filename__snprintf_build_id(pathname, real_sbuild_id, sizeof(real_sbuild_id));
 	else
 		ret = -EINVAL;	/* Should we support other special DSO cache? */
 	if (ret >= 0)
@@ -243,24 +239,26 @@ static bool build_id_cache__valid_id(char *sbuild_id)
 	return result;
 }
 
-static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso)
+static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso,
+					    bool is_debug)
 {
-	return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : "elf");
+	return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : (is_debug ?
+	    "debug" : "elf"));
 }
 
-char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size)
+char *__dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
+			       bool is_debug, bool is_kallsyms)
 {
-	bool is_kallsyms = dso__is_kallsyms((struct dso *)dso);
 	bool is_vdso = dso__is_vdso((struct dso *)dso);
 	char sbuild_id[SBUILD_ID_SIZE];
 	char *linkname;
 	bool alloc = (bf == NULL);
 	int ret;
 
-	if (!dso->has_build_id)
+	if (!dso__has_build_id(dso))
 		return NULL;
 
-	build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);
+	build_id__snprintf(dso__bid(dso), sbuild_id, sizeof(sbuild_id));
 	linkname = build_id_cache__linkname(sbuild_id, NULL, 0);
 	if (!linkname)
 		return NULL;
@@ -270,7 +268,8 @@ char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size)
 		ret = asnprintf(&bf, size, "%s", linkname);
 	else
 		ret = asnprintf(&bf, size, "%s/%s", linkname,
-			 build_id_cache__basename(is_kallsyms, is_vdso));
+			 build_id_cache__basename(is_kallsyms, is_vdso,
+						  is_debug));
 	if (ret < 0 || (!alloc && size < (unsigned int)ret))
 		bf = NULL;
 	free(linkname);
@@ -278,130 +277,108 @@ char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size)
 	return bf;
 }
 
-#define dsos__for_each_with_build_id(pos, head)	\
-	list_for_each_entry(pos, head, node)	\
-		if (!pos->has_build_id)		\
-			continue;		\
-		else
+char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
+			     bool is_debug)
+{
+	bool is_kallsyms = dso__is_kallsyms((struct dso *)dso);
 
-static int write_buildid(const char *name, size_t name_len, u8 *build_id,
-			 pid_t pid, u16 misc, int fd)
+	return __dso__build_id_filename(dso, bf, size, is_debug, is_kallsyms);
+}
+
+static int write_buildid(const char *name, size_t name_len, struct build_id *bid,
+			 pid_t pid, u16 misc, struct feat_fd *fd)
 {
 	int err;
-	struct build_id_event b;
+	struct perf_record_header_build_id b;
 	size_t len;
 
 	len = name_len + 1;
-	len = PERF_ALIGN(len, NAME_ALIGN);
+	len = PERF_ALIGN(len, sizeof(u64));
 
 	memset(&b, 0, sizeof(b));
-	memcpy(&b.build_id, build_id, BUILD_ID_SIZE);
+	memcpy(&b.data, bid->data, bid->size);
+	b.size = (u8) bid->size;
+	misc |= PERF_RECORD_MISC_BUILD_ID_SIZE;
 	b.pid = pid;
 	b.header.misc = misc;
 	b.header.size = sizeof(b) + len;
 
-	err = writen(fd, &b, sizeof(b));
+	err = do_write(fd, &b, sizeof(b));
 	if (err < 0)
 		return err;
 
 	return write_padded(fd, name, name_len + 1, len);
 }
 
-static int machine__write_buildid_table(struct machine *machine, int fd)
-{
-	int err = 0;
-	char nm[PATH_MAX];
-	struct dso *pos;
-	u16 kmisc = PERF_RECORD_MISC_KERNEL,
-	    umisc = PERF_RECORD_MISC_USER;
-
-	if (!machine__is_host(machine)) {
-		kmisc = PERF_RECORD_MISC_GUEST_KERNEL;
-		umisc = PERF_RECORD_MISC_GUEST_USER;
-	}
+struct machine__write_buildid_table_cb_args {
+	struct machine *machine;
+	struct feat_fd *fd;
+	u16 kmisc, umisc;
+};
 
-	dsos__for_each_with_build_id(pos, &machine->dsos.head) {
-		const char *name;
-		size_t name_len;
-		bool in_kernel = false;
+static int machine__write_buildid_table_cb(struct dso *dso, void *data)
+{
+	struct machine__write_buildid_table_cb_args *args = data;
+	const char *name;
+	size_t name_len;
+	bool in_kernel = false;
 
-		if (!pos->hit && !dso__is_vdso(pos))
-			continue;
+	if (!dso__has_build_id(dso))
+		return 0;
 
-		if (dso__is_vdso(pos)) {
-			name = pos->short_name;
-			name_len = pos->short_name_len;
-		} else if (dso__is_kcore(pos)) {
-			machine__mmap_name(machine, nm, sizeof(nm));
-			name = nm;
-			name_len = strlen(nm);
-		} else {
-			name = pos->long_name;
-			name_len = pos->long_name_len;
-		}
+	if (!dso__hit(dso) && !dso__is_vdso(dso))
+		return 0;
 
-		in_kernel = pos->kernel ||
-				is_kernel_module(name,
-					PERF_RECORD_MISC_CPUMODE_UNKNOWN);
-		err = write_buildid(name, name_len, pos->build_id, machine->pid,
-				    in_kernel ? kmisc : umisc, fd);
-		if (err)
-			break;
+	if (dso__is_vdso(dso)) {
+		name = dso__short_name(dso);
+		name_len = dso__short_name_len(dso);
+	} else if (dso__is_kcore(dso)) {
+		name = args->machine->mmap_name;
+		name_len = strlen(name);
+	} else {
+		name = dso__long_name(dso);
+		name_len = dso__long_name_len(dso);
 	}
 
-	return err;
+	in_kernel = dso__kernel(dso) || is_kernel_module(name, PERF_RECORD_MISC_CPUMODE_UNKNOWN);
+	return write_buildid(name, name_len, &dso__id(dso)->build_id, args->machine->pid,
+			     in_kernel ? args->kmisc : args->umisc, args->fd);
 }
 
-int perf_session__write_buildid_table(struct perf_session *session, int fd)
+static int machine__write_buildid_table(struct machine *machine, struct feat_fd *fd)
 {
-	struct rb_node *nd;
-	int err = machine__write_buildid_table(&session->machines.host, fd);
-
-	if (err)
-		return err;
+	struct machine__write_buildid_table_cb_args args = {
+		.machine = machine,
+		.fd = fd,
+		.kmisc = PERF_RECORD_MISC_KERNEL,
+		.umisc = PERF_RECORD_MISC_USER,
+	};
 
-	for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
-		struct machine *pos = rb_entry(nd, struct machine, rb_node);
-		err = machine__write_buildid_table(pos, fd);
-		if (err)
-			break;
+	if (!machine__is_host(machine)) {
+		args.kmisc = PERF_RECORD_MISC_GUEST_KERNEL;
+		args.umisc = PERF_RECORD_MISC_GUEST_USER;
 	}
-	return err;
-}
-
-static int __dsos__hit_all(struct list_head *head)
-{
-	struct dso *pos;
-
-	list_for_each_entry(pos, head, node)
-		pos->hit = true;
 
-	return 0;
-}
-
-static int machine__hit_all_dsos(struct machine *machine)
-{
-	return __dsos__hit_all(&machine->dsos.head);
+	return dsos__for_each_dso(&machine->dsos, machine__write_buildid_table_cb, &args);
 }
 
-int dsos__hit_all(struct perf_session *session)
+int perf_session__write_buildid_table(struct perf_session *session,
+				      struct feat_fd *fd)
 {
 	struct rb_node *nd;
-	int err;
+	int err = machine__write_buildid_table(&session->machines.host, fd);
 
-	err = machine__hit_all_dsos(&session->machines.host);
 	if (err)
 		return err;
 
-	for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
+	for (nd = rb_first_cached(&session->machines.guests); nd;
+	     nd = rb_next(nd)) {
 		struct machine *pos = rb_entry(nd, struct machine, rb_node);
-
-		err = machine__hit_all_dsos(pos);
+		err = machine__write_buildid_table(pos, fd);
 		if (err)
-			return err;
+			break;
 	}
-
-	return 0;
+	return err;
 }
 
 void disable_buildid_cache(void)
@@ -422,7 +399,8 @@ static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
 	int i = 0;
 	while (isxdigit(d->d_name[i]) && i < SBUILD_ID_SIZE - 3)
 		i++;
-	return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
+	return (i >= SBUILD_ID_MIN_SIZE - 3) && (i <= SBUILD_ID_SIZE - 3) &&
+		(d->d_name[i] == '\0');
 }
 
 struct strlist *build_id_cache__list_all(bool validonly)
@@ -464,7 +442,7 @@ struct strlist *build_id_cache__list_all(bool validonly)
 		}
 		strlist__for_each_entry(nd2, linklist) {
 			if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
-				     nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
+				     nd->s, nd2->s) > SBUILD_ID_SIZE - 1)
 				goto err_out;
 			if (validonly && !build_id_cache__valid_id(sbuild_id))
 				continue;
@@ -534,35 +512,31 @@ char *build_id_cache__complement(const char *incomplete_sbuild_id)
 }
 
 char *build_id_cache__cachedir(const char *sbuild_id, const char *name,
-			       bool is_kallsyms, bool is_vdso)
+			       struct nsinfo *nsi, bool is_kallsyms,
+			       bool is_vdso)
 {
-	char *realname = (char *)name, *filename;
+	char *realname = NULL, *filename;
 	bool slash = is_kallsyms || is_vdso;
 
-	if (!slash) {
-		realname = realpath(name, NULL);
-		if (!realname)
-			return NULL;
-	}
+	if (!slash)
+		realname = nsinfo__realpath(name, nsi);
 
 	if (asprintf(&filename, "%s%s%s%s%s", buildid_dir, slash ? "/" : "",
-		     is_vdso ? DSO__NAME_VDSO : realname,
+		     is_vdso ? DSO__NAME_VDSO : (realname ? realname : name),
 		     sbuild_id ? "/" : "", sbuild_id ?: "") < 0)
 		filename = NULL;
 
-	if (!slash)
-		free(realname);
-
+	free(realname);
 	return filename;
 }
 
-int build_id_cache__list_build_ids(const char *pathname,
+int build_id_cache__list_build_ids(const char *pathname, struct nsinfo *nsi,
 				   struct strlist **result)
 {
 	char *dir_name;
 	int ret = 0;
 
-	dir_name = build_id_cache__cachedir(NULL, pathname, false, false);
+	dir_name = build_id_cache__cachedir(NULL, pathname, nsi, false, false);
 	if (!dir_name)
 		return -ENOMEM;
 
@@ -576,16 +550,20 @@ int build_id_cache__list_build_ids(const char *pathname,
 
 #if defined(HAVE_LIBELF_SUPPORT) && defined(HAVE_GELF_GETNOTE_SUPPORT)
 static int build_id_cache__add_sdt_cache(const char *sbuild_id,
-					  const char *realname)
+					  const char *realname,
+					  struct nsinfo *nsi)
 {
 	struct probe_cache *cache;
 	int ret;
+	struct nscookie nsc;
 
-	cache = probe_cache__new(sbuild_id);
+	cache = probe_cache__new(sbuild_id, nsi);
 	if (!cache)
 		return -1;
 
+	nsinfo__mountns_enter(nsi, &nsc);
 	ret = probe_cache__scan_sdt(cache, realname);
+	nsinfo__mountns_exit(&nsc);
 	if (ret >= 0) {
 		pr_debug4("Found %d SDTs in %s\n", ret, realname);
 		if (probe_cache__commit(cache) < 0)
@@ -595,25 +573,77 @@ static int build_id_cache__add_sdt_cache(const char *sbuild_id,
 	return ret;
 }
 #else
-#define build_id_cache__add_sdt_cache(sbuild_id, realname) (0)
+#define build_id_cache__add_sdt_cache(sbuild_id, realname, nsi) (0)
+#endif
+
+static char *build_id_cache__find_debug(const char *sbuild_id,
+					struct nsinfo *nsi,
+					const char *root_dir)
+{
+	const char *dirname = "/usr/lib/debug/.build-id/";
+	char *realname = NULL;
+	char dirbuf[PATH_MAX];
+	char *debugfile;
+	struct nscookie nsc;
+	size_t len = 0;
+
+	debugfile = calloc(1, PATH_MAX);
+	if (!debugfile)
+		goto out;
+
+	if (root_dir) {
+		path__join(dirbuf, PATH_MAX, root_dir, dirname);
+		dirname = dirbuf;
+	}
+
+	len = __symbol__join_symfs(debugfile, PATH_MAX, dirname);
+	snprintf(debugfile + len, PATH_MAX - len, "%.2s/%s.debug", sbuild_id,
+		 sbuild_id + 2);
+
+	nsinfo__mountns_enter(nsi, &nsc);
+	realname = realpath(debugfile, NULL);
+	if (realname && access(realname, R_OK))
+		zfree(&realname);
+	nsinfo__mountns_exit(&nsc);
+
+#ifdef HAVE_DEBUGINFOD_SUPPORT
+	if (realname == NULL) {
+		debuginfod_client* c;
+
+		pr_debug("Downloading debug info with build id %s\n", sbuild_id);
+
+		c = debuginfod_begin();
+		if (c != NULL) {
+			int fd = debuginfod_find_debuginfo(c,
+					(const unsigned char*)sbuild_id, 0,
+					&realname);
+			if (fd >= 0)
+				close(fd); /* retaining reference by realname */
+			debuginfod_end(c);
+		}
+	}
 #endif
 
-int build_id_cache__add_s(const char *sbuild_id, const char *name,
-			  bool is_kallsyms, bool is_vdso)
+out:
+	free(debugfile);
+	return realname;
+}
+
+int
+build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
+		    struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
+		    const char *proper_name, const char *root_dir)
 {
 	const size_t size = PATH_MAX;
-	char *realname = NULL, *filename = NULL, *dir_name = NULL,
-	     *linkname = zalloc(size), *tmp;
+	char *filename = NULL, *dir_name = NULL, *linkname = zalloc(size), *tmp;
+	char *debugfile = NULL;
 	int err = -1;
 
-	if (!is_kallsyms) {
-		realname = realpath(name, NULL);
-		if (!realname)
-			goto out_free;
-	}
+	if (!proper_name)
+		proper_name = name;
 
-	dir_name = build_id_cache__cachedir(sbuild_id, name,
-					    is_kallsyms, is_vdso);
+	dir_name = build_id_cache__cachedir(sbuild_id, proper_name, nsi, is_kallsyms,
+					    is_vdso);
 	if (!dir_name)
 		goto out_free;
 
@@ -627,18 +657,54 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
 
 	/* Save the allocated buildid dirname */
 	if (asprintf(&filename, "%s/%s", dir_name,
-		     build_id_cache__basename(is_kallsyms, is_vdso)) < 0) {
+		     build_id_cache__basename(is_kallsyms, is_vdso,
+		     false)) < 0) {
 		filename = NULL;
 		goto out_free;
 	}
 
 	if (access(filename, F_OK)) {
 		if (is_kallsyms) {
-			 if (copyfile("/proc/kallsyms", filename))
+			if (copyfile("/proc/kallsyms", filename))
 				goto out_free;
-		} else if (link(realname, filename) && errno != EEXIST &&
-				copyfile(name, filename))
-			goto out_free;
+		} else if (nsi && nsinfo__need_setns(nsi)) {
+			if (copyfile_ns(name, filename, nsi))
+				goto out_free;
+		} else if (link(realname, filename) && errno != EEXIST) {
+			struct stat f_stat;
+
+			if (!(stat(name, &f_stat) < 0) &&
+					copyfile_mode(name, filename, f_stat.st_mode))
+				goto out_free;
+		}
+	}
+
+	/* Some binaries are stripped, but have .debug files with their symbol
+	 * table.  Check to see if we can locate one of those, since the elf
+	 * file itself may not be very useful to users of our tools without a
+	 * symtab.
+	 */
+	if (!is_kallsyms && !is_vdso &&
+	    strncmp(".ko", name + strlen(name) - 3, 3)) {
+		debugfile = build_id_cache__find_debug(sbuild_id, nsi, root_dir);
+		if (debugfile) {
+			zfree(&filename);
+			if (asprintf(&filename, "%s/%s", dir_name,
+			    build_id_cache__basename(false, false, true)) < 0) {
+				filename = NULL;
+				goto out_free;
+			}
+			if (access(filename, F_OK)) {
+				if (nsi && nsinfo__need_setns(nsi)) {
+					if (copyfile_ns(debugfile, filename,
+							nsi))
+						goto out_free;
+				} else if (link(debugfile, filename) &&
+						errno != EEXIST &&
+						copyfile(debugfile, filename))
+					goto out_free;
+			}
+		}
 	}
 
 	if (!build_id_cache__linkname(sbuild_id, linkname, size))
@@ -653,31 +719,75 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
 	tmp = dir_name + strlen(buildid_dir) - 5;
 	memcpy(tmp, "../..", 5);
 
-	if (symlink(tmp, linkname) == 0)
+	if (symlink(tmp, linkname) == 0) {
 		err = 0;
+	} else if (errno == EEXIST) {
+		char path[PATH_MAX];
+		ssize_t len;
+
+		len = readlink(linkname, path, sizeof(path) - 1);
+		if (len <= 0) {
+			pr_err("Can't read link: %s\n", linkname);
+			goto out_free;
+		}
+		path[len] = '\0';
+
+		if (strcmp(tmp, path)) {
+			pr_debug("build <%s> already linked to %s\n",
+				 sbuild_id, linkname);
+		}
+		err = 0;
+	}
 
 	/* Update SDT cache : error is just warned */
-	if (realname && build_id_cache__add_sdt_cache(sbuild_id, realname) < 0)
+	if (realname &&
+	    build_id_cache__add_sdt_cache(sbuild_id, realname, nsi) < 0)
 		pr_debug4("Failed to update/scan SDT cache for %s\n", realname);
 
 out_free:
-	if (!is_kallsyms)
-		free(realname);
 	free(filename);
+	free(debugfile);
 	free(dir_name);
 	free(linkname);
 	return err;
 }
 
-static int build_id_cache__add_b(const u8 *build_id, size_t build_id_size,
-				 const char *name, bool is_kallsyms,
-				 bool is_vdso)
+int __build_id_cache__add_s(const char *sbuild_id, const char *name,
+			    struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
+			    const char *proper_name, const char *root_dir)
+{
+	char *realname = NULL;
+	int err = -1;
+
+	if (!is_kallsyms) {
+		if (!is_vdso)
+			realname = nsinfo__realpath(name, nsi);
+		else
+			realname = realpath(name, NULL);
+		if (!realname)
+			goto out_free;
+	}
+
+	err = build_id_cache__add(sbuild_id, name, realname, nsi,
+				  is_kallsyms, is_vdso, proper_name, root_dir);
+out_free:
+	if (!is_kallsyms)
+		free(realname);
+	return err;
+}
+
+static int build_id_cache__add_b(const struct build_id *bid,
+				 const char *name, struct nsinfo *nsi,
+				 bool is_kallsyms, bool is_vdso,
+				 const char *proper_name,
+				 const char *root_dir)
 {
 	char sbuild_id[SBUILD_ID_SIZE];
 
-	build_id__sprintf(build_id, build_id_size, sbuild_id);
+	build_id__snprintf(bid, sbuild_id, sizeof(sbuild_id));
 
-	return build_id_cache__add_s(sbuild_id, name, is_kallsyms, is_vdso);
+	return __build_id_cache__add_s(sbuild_id, name, nsi, is_kallsyms,
+				       is_vdso, proper_name, root_dir);
 }
 
 bool build_id_cache__cached(const char *sbuild_id)
@@ -730,63 +840,114 @@ out_free:
 	return err;
 }
 
-static int dso__cache_build_id(struct dso *dso, struct machine *machine)
+static int filename__read_build_id_ns(const char *filename,
+				      struct build_id *bid,
+				      struct nsinfo *nsi)
+{
+	struct nscookie nsc;
+	int ret;
+
+	nsinfo__mountns_enter(nsi, &nsc);
+	ret = filename__read_build_id(filename, bid);
+	nsinfo__mountns_exit(&nsc);
+
+	return ret;
+}
+
+static bool dso__build_id_mismatch(struct dso *dso, const char *name)
+{
+	struct build_id bid = { .size = 0, };
+	bool ret = false;
+
+	mutex_lock(dso__lock(dso));
+	if (filename__read_build_id_ns(name, &bid, dso__nsinfo(dso)) >= 0)
+		ret = !dso__build_id_equal(dso, &bid);
+
+	mutex_unlock(dso__lock(dso));
+
+	return ret;
+}
+
+static int dso__cache_build_id(struct dso *dso, struct machine *machine,
+			       void *priv __maybe_unused)
 {
 	bool is_kallsyms = dso__is_kallsyms(dso);
 	bool is_vdso = dso__is_vdso(dso);
-	const char *name = dso->long_name;
-	char nm[PATH_MAX];
+	const char *name = dso__long_name(dso);
+	const char *proper_name = NULL;
+	const char *root_dir = NULL;
+	char *allocated_name = NULL;
+	int ret = 0;
+
+	if (!dso__has_build_id(dso) || !dso__hit(dso))
+		return 0;
 
 	if (dso__is_kcore(dso)) {
 		is_kallsyms = true;
-		machine__mmap_name(machine, nm, sizeof(nm));
-		name = nm;
+		name = machine->mmap_name;
 	}
-	return build_id_cache__add_b(dso->build_id, sizeof(dso->build_id), name,
-				     is_kallsyms, is_vdso);
-}
 
-static int __dsos__cache_build_ids(struct list_head *head,
-				   struct machine *machine)
-{
-	struct dso *pos;
-	int err = 0;
+	if (!machine__is_host(machine)) {
+		if (*machine->root_dir) {
+			root_dir = machine->root_dir;
+			ret = asprintf(&allocated_name, "%s/%s", root_dir, name);
+			if (ret < 0)
+				return ret;
+			proper_name = name;
+			name = allocated_name;
+		} else if (is_kallsyms) {
+			/* Cannot get guest kallsyms */
+			return 0;
+		}
+	}
 
-	dsos__for_each_with_build_id(pos, head)
-		if (dso__cache_build_id(pos, machine))
-			err = -1;
+	if (!is_kallsyms && dso__build_id_mismatch(dso, name))
+		goto out_free;
 
-	return err;
+	mutex_lock(dso__lock(dso));
+	ret = build_id_cache__add_b(dso__bid(dso), name, dso__nsinfo(dso),
+				    is_kallsyms, is_vdso, proper_name, root_dir);
+	mutex_unlock(dso__lock(dso));
+out_free:
+	free(allocated_name);
+	return ret;
 }
 
-static int machine__cache_build_ids(struct machine *machine)
+static int
+machines__for_each_dso(struct machines *machines, machine__dso_t fn, void *priv)
 {
-	return __dsos__cache_build_ids(&machine->dsos.head, machine);
+	int ret = machine__for_each_dso(&machines->host, fn, priv);
+	struct rb_node *nd;
+
+	for (nd = rb_first_cached(&machines->guests); nd;
+	     nd = rb_next(nd)) {
+		struct machine *pos = rb_entry(nd, struct machine, rb_node);
+
+		ret |= machine__for_each_dso(pos, fn, priv);
+	}
+	return ret ? -1 : 0;
 }
 
-int perf_session__cache_build_ids(struct perf_session *session)
+int __perf_session__cache_build_ids(struct perf_session *session,
+				    machine__dso_t fn, void *priv)
 {
-	struct rb_node *nd;
-	int ret;
-
 	if (no_buildid_cache)
 		return 0;
 
 	if (mkdir(buildid_dir, 0755) != 0 && errno != EEXIST)
 		return -1;
 
-	ret = machine__cache_build_ids(&session->machines.host);
+	return machines__for_each_dso(&session->machines, fn, priv) ?  -1 : 0;
+}
 
-	for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
-		struct machine *pos = rb_entry(nd, struct machine, rb_node);
-		ret |= machine__cache_build_ids(pos);
-	}
-	return ret ? -1 : 0;
+int perf_session__cache_build_ids(struct perf_session *session)
+{
+	return __perf_session__cache_build_ids(session, dso__cache_build_id, NULL);
 }
 
 static bool machine__read_build_ids(struct machine *machine, bool with_hits)
 {
-	return __dsos__read_build_ids(&machine->dsos.head, with_hits);
+	return dsos__read_build_ids(&machine->dsos, with_hits);
 }
 
 bool perf_session__read_build_ids(struct perf_session *session, bool with_hits)
@@ -794,10 +955,26 @@ bool perf_session__read_build_ids(struct perf_session *session, bool with_hits)
 	struct rb_node *nd;
 	bool ret = machine__read_build_ids(&session->machines.host, with_hits);
 
-	for (nd = rb_first(&session->machines.guests); nd; nd = rb_next(nd)) {
+	for (nd = rb_first_cached(&session->machines.guests); nd;
+	     nd = rb_next(nd)) {
 		struct machine *pos = rb_entry(nd, struct machine, rb_node);
 		ret |= machine__read_build_ids(pos, with_hits);
 	}
 
 	return ret;
 }
+
+void build_id__init(struct build_id *bid, const u8 *data, size_t size)
+{
+	if (size > BUILD_ID_SIZE) {
+		pr_debug("Truncating build_id size from %zd\n", size);
+		size = BUILD_ID_SIZE;
+	}
+	memcpy(bid->data, data, size);
+	bid->size = size;
+}
+
+bool build_id__is_defined(const struct build_id *bid)
+{
+	return bid && bid->size ? !!memchr_inv(bid->data, 0, bid->size) : false;
+}