diff mbox series

[08/35] perf buildid-cache: Add guestmount'd files to the build ID cache

Message ID 20220711093218.10967-9-adrian.hunter@intel.com (mailing list archive)
State New, archived
Headers show
Series perf intel-pt: Add support for tracing virtual machine user space on the host | expand

Commit Message

Adrian Hunter July 11, 2022, 9:31 a.m. UTC
When the guestmount option is used, a guest machine's file system mount
point is recorded in machine->root_dir.

perf already iterates guest machines when adding files to the build ID
cache, but does not take machine->root_dir into account.

Use machine->root_dir to find files for guest build IDs, and add them to
the build ID cache using the "proper" name i.e. relative to the guest root
directory not the host root directory.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 tools/perf/util/build-id.c | 67 +++++++++++++++++++++++++++++---------
 tools/perf/util/build-id.h | 16 ++++++---
 2 files changed, 63 insertions(+), 20 deletions(-)

Comments

Ian Rogers July 19, 2022, 5:41 p.m. UTC | #1
On Mon, Jul 11, 2022 at 2:33 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> When the guestmount option is used, a guest machine's file system mount
> point is recorded in machine->root_dir.
>
> perf already iterates guest machines when adding files to the build ID
> cache, but does not take machine->root_dir into account.
>
> Use machine->root_dir to find files for guest build IDs, and add them to
> the build ID cache using the "proper" name i.e. relative to the guest root
> directory not the host root directory.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>

Is it plausible to add a test for this? Our tests create workload but
there's no existing hypervisor way to do this. Perhaps the test can
run in a hypervisor? Or maybe there's a route that doesn't involve
hypervisors.

Acked-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
>  tools/perf/util/build-id.c | 67 +++++++++++++++++++++++++++++---------
>  tools/perf/util/build-id.h | 16 ++++++---
>  2 files changed, 63 insertions(+), 20 deletions(-)
>
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index 4c9093b64d1f..7c9f441936ee 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -625,9 +625,12 @@ static int build_id_cache__add_sdt_cache(const char *sbuild_id,
>  #endif
>
>  static char *build_id_cache__find_debug(const char *sbuild_id,
> -                                       struct nsinfo *nsi)
> +                                       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;
> @@ -636,8 +639,12 @@ static char *build_id_cache__find_debug(const char *sbuild_id,
>         if (!debugfile)
>                 goto out;
>
> -       len = __symbol__join_symfs(debugfile, PATH_MAX,
> -                                  "/usr/lib/debug/.build-id/");
> +       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);
>
> @@ -668,14 +675,18 @@ static char *build_id_cache__find_debug(const char *sbuild_id,
>
>  int
>  build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
> -                   struct nsinfo *nsi, bool is_kallsyms, bool is_vdso)
> +                   struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
> +                   const char *proper_name, const char *root_dir)
>  {
>         const size_t size = PATH_MAX;
>         char *filename = NULL, *dir_name = NULL, *linkname = zalloc(size), *tmp;
>         char *debugfile = NULL;
>         int err = -1;
>
> -       dir_name = build_id_cache__cachedir(sbuild_id, name, nsi, is_kallsyms,
> +       if (!proper_name)
> +               proper_name = name;
> +
> +       dir_name = build_id_cache__cachedir(sbuild_id, proper_name, nsi, is_kallsyms,
>                                             is_vdso);
>         if (!dir_name)
>                 goto out_free;
> @@ -715,7 +726,7 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
>          */
>         if (!is_kallsyms && !is_vdso &&
>             strncmp(".ko", name + strlen(name) - 3, 3)) {
> -               debugfile = build_id_cache__find_debug(sbuild_id, nsi);
> +               debugfile = build_id_cache__find_debug(sbuild_id, nsi, root_dir);
>                 if (debugfile) {
>                         zfree(&filename);
>                         if (asprintf(&filename, "%s/%s", dir_name,
> @@ -781,8 +792,9 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
>         return err;
>  }
>
> -int build_id_cache__add_s(const char *sbuild_id, const char *name,
> -                         struct nsinfo *nsi, 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;
> @@ -796,8 +808,8 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
>                         goto out_free;
>         }
>
> -       err = build_id_cache__add(sbuild_id, name, realname, nsi, is_kallsyms, is_vdso);
> -
> +       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);
> @@ -806,14 +818,16 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
>
>  static int build_id_cache__add_b(const struct build_id *bid,
>                                  const char *name, struct nsinfo *nsi,
> -                                bool is_kallsyms, bool is_vdso)
> +                                bool is_kallsyms, bool is_vdso,
> +                                const char *proper_name,
> +                                const char *root_dir)
>  {
>         char sbuild_id[SBUILD_ID_SIZE];
>
>         build_id__sprintf(bid, sbuild_id);
>
> -       return build_id_cache__add_s(sbuild_id, name, nsi, 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)
> @@ -896,6 +910,10 @@ static int dso__cache_build_id(struct dso *dso, struct machine *machine,
>         bool is_kallsyms = dso__is_kallsyms(dso);
>         bool is_vdso = dso__is_vdso(dso);
>         const char *name = dso->long_name;
> +       const char *proper_name = NULL;
> +       const char *root_dir = NULL;
> +       char *allocated_name = NULL;
> +       int ret = 0;
>
>         if (!dso->has_build_id)
>                 return 0;
> @@ -905,11 +923,28 @@ static int dso__cache_build_id(struct dso *dso, struct machine *machine,
>                 name = machine->mmap_name;
>         }
>
> +       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;
> +               }
> +       }
> +
>         if (!is_kallsyms && dso__build_id_mismatch(dso, name))
> -               return 0;
> +               goto out_free;
>
> -       return build_id_cache__add_b(&dso->bid, name, dso->nsinfo,
> -                                    is_kallsyms, is_vdso);
> +       ret = build_id_cache__add_b(&dso->bid, name, dso->nsinfo,
> +                                   is_kallsyms, is_vdso, proper_name, root_dir);
> +out_free:
> +       free(allocated_name);
> +       return ret;
>  }
>
>  static int
> diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
> index c19617151670..4e3a1169379b 100644
> --- a/tools/perf/util/build-id.h
> +++ b/tools/perf/util/build-id.h
> @@ -66,10 +66,18 @@ int build_id_cache__list_build_ids(const char *pathname, struct nsinfo *nsi,
>                                    struct strlist **result);
>  bool build_id_cache__cached(const char *sbuild_id);
>  int build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
> -                       struct nsinfo *nsi, 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);
> +                       struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
> +                       const char *proper_name, const char *root_dir);
> +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);
> +static inline int build_id_cache__add_s(const char *sbuild_id,
> +                                       const char *name, struct nsinfo *nsi,
> +                                       bool is_kallsyms, bool is_vdso)
> +{
> +       return __build_id_cache__add_s(sbuild_id, name, nsi, is_kallsyms, is_vdso, NULL, NULL);
> +}
>  int build_id_cache__remove_s(const char *sbuild_id);
>
>  extern char buildid_dir[];
> --
> 2.25.1
>
Adrian Hunter Aug. 9, 2022, 12:21 p.m. UTC | #2
On 19/07/22 20:41, Ian Rogers wrote:
> On Mon, Jul 11, 2022 at 2:33 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>>
>> When the guestmount option is used, a guest machine's file system mount
>> point is recorded in machine->root_dir.
>>
>> perf already iterates guest machines when adding files to the build ID
>> cache, but does not take machine->root_dir into account.
>>
>> Use machine->root_dir to find files for guest build IDs, and add them to
>> the build ID cache using the "proper" name i.e. relative to the guest root
>> directory not the host root directory.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> 
> Is it plausible to add a test for this? Our tests create workload but
> there's no existing hypervisor way to do this. Perhaps the test can
> run in a hypervisor? Or maybe there's a route that doesn't involve
> hypervisors.

Too complicated I think.

> 
> Acked-by: Ian Rogers <irogers@google.com>
> 
> Thanks,
> Ian
> 
>> ---
>>  tools/perf/util/build-id.c | 67 +++++++++++++++++++++++++++++---------
>>  tools/perf/util/build-id.h | 16 ++++++---
>>  2 files changed, 63 insertions(+), 20 deletions(-)
>>
>> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
>> index 4c9093b64d1f..7c9f441936ee 100644
>> --- a/tools/perf/util/build-id.c
>> +++ b/tools/perf/util/build-id.c
>> @@ -625,9 +625,12 @@ static int build_id_cache__add_sdt_cache(const char *sbuild_id,
>>  #endif
>>
>>  static char *build_id_cache__find_debug(const char *sbuild_id,
>> -                                       struct nsinfo *nsi)
>> +                                       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;
>> @@ -636,8 +639,12 @@ static char *build_id_cache__find_debug(const char *sbuild_id,
>>         if (!debugfile)
>>                 goto out;
>>
>> -       len = __symbol__join_symfs(debugfile, PATH_MAX,
>> -                                  "/usr/lib/debug/.build-id/");
>> +       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);
>>
>> @@ -668,14 +675,18 @@ static char *build_id_cache__find_debug(const char *sbuild_id,
>>
>>  int
>>  build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
>> -                   struct nsinfo *nsi, bool is_kallsyms, bool is_vdso)
>> +                   struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
>> +                   const char *proper_name, const char *root_dir)
>>  {
>>         const size_t size = PATH_MAX;
>>         char *filename = NULL, *dir_name = NULL, *linkname = zalloc(size), *tmp;
>>         char *debugfile = NULL;
>>         int err = -1;
>>
>> -       dir_name = build_id_cache__cachedir(sbuild_id, name, nsi, is_kallsyms,
>> +       if (!proper_name)
>> +               proper_name = name;
>> +
>> +       dir_name = build_id_cache__cachedir(sbuild_id, proper_name, nsi, is_kallsyms,
>>                                             is_vdso);
>>         if (!dir_name)
>>                 goto out_free;
>> @@ -715,7 +726,7 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
>>          */
>>         if (!is_kallsyms && !is_vdso &&
>>             strncmp(".ko", name + strlen(name) - 3, 3)) {
>> -               debugfile = build_id_cache__find_debug(sbuild_id, nsi);
>> +               debugfile = build_id_cache__find_debug(sbuild_id, nsi, root_dir);
>>                 if (debugfile) {
>>                         zfree(&filename);
>>                         if (asprintf(&filename, "%s/%s", dir_name,
>> @@ -781,8 +792,9 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
>>         return err;
>>  }
>>
>> -int build_id_cache__add_s(const char *sbuild_id, const char *name,
>> -                         struct nsinfo *nsi, 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;
>> @@ -796,8 +808,8 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
>>                         goto out_free;
>>         }
>>
>> -       err = build_id_cache__add(sbuild_id, name, realname, nsi, is_kallsyms, is_vdso);
>> -
>> +       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);
>> @@ -806,14 +818,16 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
>>
>>  static int build_id_cache__add_b(const struct build_id *bid,
>>                                  const char *name, struct nsinfo *nsi,
>> -                                bool is_kallsyms, bool is_vdso)
>> +                                bool is_kallsyms, bool is_vdso,
>> +                                const char *proper_name,
>> +                                const char *root_dir)
>>  {
>>         char sbuild_id[SBUILD_ID_SIZE];
>>
>>         build_id__sprintf(bid, sbuild_id);
>>
>> -       return build_id_cache__add_s(sbuild_id, name, nsi, 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)
>> @@ -896,6 +910,10 @@ static int dso__cache_build_id(struct dso *dso, struct machine *machine,
>>         bool is_kallsyms = dso__is_kallsyms(dso);
>>         bool is_vdso = dso__is_vdso(dso);
>>         const char *name = dso->long_name;
>> +       const char *proper_name = NULL;
>> +       const char *root_dir = NULL;
>> +       char *allocated_name = NULL;
>> +       int ret = 0;
>>
>>         if (!dso->has_build_id)
>>                 return 0;
>> @@ -905,11 +923,28 @@ static int dso__cache_build_id(struct dso *dso, struct machine *machine,
>>                 name = machine->mmap_name;
>>         }
>>
>> +       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;
>> +               }
>> +       }
>> +
>>         if (!is_kallsyms && dso__build_id_mismatch(dso, name))
>> -               return 0;
>> +               goto out_free;
>>
>> -       return build_id_cache__add_b(&dso->bid, name, dso->nsinfo,
>> -                                    is_kallsyms, is_vdso);
>> +       ret = build_id_cache__add_b(&dso->bid, name, dso->nsinfo,
>> +                                   is_kallsyms, is_vdso, proper_name, root_dir);
>> +out_free:
>> +       free(allocated_name);
>> +       return ret;
>>  }
>>
>>  static int
>> diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
>> index c19617151670..4e3a1169379b 100644
>> --- a/tools/perf/util/build-id.h
>> +++ b/tools/perf/util/build-id.h
>> @@ -66,10 +66,18 @@ int build_id_cache__list_build_ids(const char *pathname, struct nsinfo *nsi,
>>                                    struct strlist **result);
>>  bool build_id_cache__cached(const char *sbuild_id);
>>  int build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
>> -                       struct nsinfo *nsi, 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);
>> +                       struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
>> +                       const char *proper_name, const char *root_dir);
>> +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);
>> +static inline int build_id_cache__add_s(const char *sbuild_id,
>> +                                       const char *name, struct nsinfo *nsi,
>> +                                       bool is_kallsyms, bool is_vdso)
>> +{
>> +       return __build_id_cache__add_s(sbuild_id, name, nsi, is_kallsyms, is_vdso, NULL, NULL);
>> +}
>>  int build_id_cache__remove_s(const char *sbuild_id);
>>
>>  extern char buildid_dir[];
>> --
>> 2.25.1
>>
diff mbox series

Patch

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 4c9093b64d1f..7c9f441936ee 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -625,9 +625,12 @@  static int build_id_cache__add_sdt_cache(const char *sbuild_id,
 #endif
 
 static char *build_id_cache__find_debug(const char *sbuild_id,
-					struct nsinfo *nsi)
+					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;
@@ -636,8 +639,12 @@  static char *build_id_cache__find_debug(const char *sbuild_id,
 	if (!debugfile)
 		goto out;
 
-	len = __symbol__join_symfs(debugfile, PATH_MAX,
-				   "/usr/lib/debug/.build-id/");
+	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);
 
@@ -668,14 +675,18 @@  static char *build_id_cache__find_debug(const char *sbuild_id,
 
 int
 build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
-		    struct nsinfo *nsi, bool is_kallsyms, bool is_vdso)
+		    struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
+		    const char *proper_name, const char *root_dir)
 {
 	const size_t size = PATH_MAX;
 	char *filename = NULL, *dir_name = NULL, *linkname = zalloc(size), *tmp;
 	char *debugfile = NULL;
 	int err = -1;
 
-	dir_name = build_id_cache__cachedir(sbuild_id, name, nsi, is_kallsyms,
+	if (!proper_name)
+		proper_name = name;
+
+	dir_name = build_id_cache__cachedir(sbuild_id, proper_name, nsi, is_kallsyms,
 					    is_vdso);
 	if (!dir_name)
 		goto out_free;
@@ -715,7 +726,7 @@  build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
 	 */
 	if (!is_kallsyms && !is_vdso &&
 	    strncmp(".ko", name + strlen(name) - 3, 3)) {
-		debugfile = build_id_cache__find_debug(sbuild_id, nsi);
+		debugfile = build_id_cache__find_debug(sbuild_id, nsi, root_dir);
 		if (debugfile) {
 			zfree(&filename);
 			if (asprintf(&filename, "%s/%s", dir_name,
@@ -781,8 +792,9 @@  build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
 	return err;
 }
 
-int build_id_cache__add_s(const char *sbuild_id, const char *name,
-			  struct nsinfo *nsi, 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;
@@ -796,8 +808,8 @@  int build_id_cache__add_s(const char *sbuild_id, const char *name,
 			goto out_free;
 	}
 
-	err = build_id_cache__add(sbuild_id, name, realname, nsi, is_kallsyms, is_vdso);
-
+	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);
@@ -806,14 +818,16 @@  int build_id_cache__add_s(const char *sbuild_id, const char *name,
 
 static int build_id_cache__add_b(const struct build_id *bid,
 				 const char *name, struct nsinfo *nsi,
-				 bool is_kallsyms, bool is_vdso)
+				 bool is_kallsyms, bool is_vdso,
+				 const char *proper_name,
+				 const char *root_dir)
 {
 	char sbuild_id[SBUILD_ID_SIZE];
 
 	build_id__sprintf(bid, sbuild_id);
 
-	return build_id_cache__add_s(sbuild_id, name, nsi, 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)
@@ -896,6 +910,10 @@  static int dso__cache_build_id(struct dso *dso, struct machine *machine,
 	bool is_kallsyms = dso__is_kallsyms(dso);
 	bool is_vdso = dso__is_vdso(dso);
 	const char *name = dso->long_name;
+	const char *proper_name = NULL;
+	const char *root_dir = NULL;
+	char *allocated_name = NULL;
+	int ret = 0;
 
 	if (!dso->has_build_id)
 		return 0;
@@ -905,11 +923,28 @@  static int dso__cache_build_id(struct dso *dso, struct machine *machine,
 		name = machine->mmap_name;
 	}
 
+	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;
+		}
+	}
+
 	if (!is_kallsyms && dso__build_id_mismatch(dso, name))
-		return 0;
+		goto out_free;
 
-	return build_id_cache__add_b(&dso->bid, name, dso->nsinfo,
-				     is_kallsyms, is_vdso);
+	ret = build_id_cache__add_b(&dso->bid, name, dso->nsinfo,
+				    is_kallsyms, is_vdso, proper_name, root_dir);
+out_free:
+	free(allocated_name);
+	return ret;
 }
 
 static int
diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
index c19617151670..4e3a1169379b 100644
--- a/tools/perf/util/build-id.h
+++ b/tools/perf/util/build-id.h
@@ -66,10 +66,18 @@  int build_id_cache__list_build_ids(const char *pathname, struct nsinfo *nsi,
 				   struct strlist **result);
 bool build_id_cache__cached(const char *sbuild_id);
 int build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
-			struct nsinfo *nsi, 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);
+			struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
+			const char *proper_name, const char *root_dir);
+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);
+static inline int build_id_cache__add_s(const char *sbuild_id,
+					const char *name, struct nsinfo *nsi,
+					bool is_kallsyms, bool is_vdso)
+{
+	return __build_id_cache__add_s(sbuild_id, name, nsi, is_kallsyms, is_vdso, NULL, NULL);
+}
 int build_id_cache__remove_s(const char *sbuild_id);
 
 extern char buildid_dir[];