[PATCH v2] perf buildid-cache: recognize vdso when adding files

[Changbin Du <changbin.du@huawei.com>]

Identify vdso by file name matching. The vdso objects have name
as vdso[32,64].so[.dbg].

$ perf buildid-cache -a /work/linux/arch/x86/entry/vdso/vdso64.so.dbg

Without this change, added vdso using above command actually will never
be used.

Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Changbin Du <changbin.du@huawei.com>

---
This patch is separated from the series "perf: Support searching local
debugging vdso or specify vdso path in cmdline".

v2: also update build_id_cache__update_file().
---
 tools/perf/builtin-buildid-cache.c | 34 ++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
index b0511d16aeb6..69f43460d007 100644
--- a/tools/perf/builtin-buildid-cache.c
+++ b/tools/perf/builtin-buildid-cache.c
@@ -172,6 +172,36 @@ static int build_id_cache__add_kcore(const char *filename, bool force)
 	return 0;
 }
 
+static bool filename_is_vdso(const char *filename)
+{
+	bool is_vdso = false;
+	char *fname, *bname;
+	static const char * const vdso_names[] = {
+		"vdso.so", "vdso32.so", "vdso64.so", "vdsox32.so"
+	};
+
+	fname = strdup(filename);
+	if (!fname) {
+		pr_err("no memory\n");
+		return false;
+	}
+
+	bname = basename(fname);
+	if (!bname)
+		goto out;
+
+	for (unsigned int i = 0; i < ARRAY_SIZE(vdso_names); i++) {
+		if (strstarts(bname, vdso_names[i])) {
+			is_vdso = true;
+			break;
+		}
+	}
+
+out:
+	free(fname);
+	return is_vdso;
+}
+
 static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
 {
 	char sbuild_id[SBUILD_ID_SIZE];
@@ -189,7 +219,7 @@ static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
 
 	build_id__sprintf(&bid, sbuild_id);
 	err = build_id_cache__add_s(sbuild_id, filename, nsi,
-				    false, false);
+				    false, filename_is_vdso(filename));
 	pr_debug("Adding %s %s: %s\n", sbuild_id, filename,
 		 err ? "FAIL" : "Ok");
 	return err;
@@ -323,7 +353,7 @@ static int build_id_cache__update_file(const char *filename, struct nsinfo *nsi)
 
 	if (!err)
 		err = build_id_cache__add_s(sbuild_id, filename, nsi, false,
-					    false);
+					    filename_is_vdso(filename));
 
 	pr_debug("Updating %s %s: %s\n", sbuild_id, filename,
 		 err ? "FAIL" : "Ok");
-- 
2.34.1