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

Adrian Hunter
2022-08-09T12:21:49Z

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
>>