Re: [PATCH v3 1/3] perf annotate: Fix a bug reading link name from a build-id file

From: Arnaldo Carvalho de Melo
Date: Mon Mar 27 2017 - 14:11:51 EST


Em Mon, Mar 27, 2017 at 04:10:36PM +0900, Taeung Song escreveu:
> It is wrong way to read link name from a build-id file.
> Because a build-id file is not symbolic link
> but build-id directory of it is symbolic link, so fix it.

Ok, applied, in the past it was always a symlink, but the following cset
changed that, so I added:

Fixes: 01412261d994 ("perf buildid-cache: Use path/to/bin/buildid/elf instead of path/to/bin/buildid")

Thanks,

- Arnaldo

> For example, if build-id file name gotten from
> dso__build_id_filename() is as below,
>
> /root/.debug/.build-id/4f/75c7d197c951659d1c1b8b5fd49bcdf8f3f8b1/elf
>
> To correctly read link name of build-id,
> use the build-id dir path that is a symbolic link,
> instead of the above build-id file name like below.
>
> /root/.debug/.build-id/4f/75c7d197c951659d1c1b8b5fd49bcdf8f3f8b1
>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
> ---
> tools/perf/util/annotate.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
> index 3d0263e..6dc9148 100644
> --- a/tools/perf/util/annotate.c
> +++ b/tools/perf/util/annotate.c
> @@ -1307,6 +1307,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
> {
> char linkname[PATH_MAX];
> char *build_id_filename;
> + char *build_id_path = NULL;
>
> if (dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
> !dso__is_kcore(dso))
> @@ -1322,8 +1323,14 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
> goto fallback;
> }
>
> + build_id_path = strdup(filename);
> + if (!build_id_path)
> + return -1;
> +
> + dirname(build_id_path);
> +
> if (dso__is_kcore(dso) ||
> - readlink(filename, linkname, sizeof(linkname)) < 0 ||
> + readlink(build_id_path, linkname, sizeof(linkname)) < 0 ||
> strstr(linkname, DSO__NAME_KALLSYMS) ||
> access(filename, R_OK)) {
> fallback:
> @@ -1335,6 +1342,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
> __symbol__join_symfs(filename, filename_size, dso->long_name);
> }
>
> + free(build_id_path);
> return 0;
> }
>
> --
> 2.7.4