[PATCH AUTOSEL for 4.9 070/219] perf annotate: Fix a bug following symbolic link of a build-id file

Sasha Levin
2018-03-03T23:53:30Z

From: Taeung Song <treeze.taeung@gmail.com>

[ Upstream commit 6ebd2547dd24daf95a21b2bc59931de8502afcc3 ]

It is wrong way to read link name from a build-id file. Because a
build-id file is not anymore a symbolic link but build-id directory of
it is symbolic link, so fix it.

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

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1490598638-13947-2-git-send-email-treeze.taeung@gmail.com
Fixes: 01412261d994 ("perf buildid-cache: Use path/to/bin/buildid/elf instead of path/to/bin/buildid")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
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 430d039d0079..a38227eb5450 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1250,6 +1250,7 @@ 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))
@@ -1265,8 +1266,14 @@ 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:
@@ -1278,6 +1285,7 @@ fallback:
__symbol__join_symfs(filename, filename_size, dso->long_name);
}

+ free(build_id_path);
return 0;
}

--
2.14.1