perf buildid-cache: Add --update option

When adding vmlinux file to build-id cache, it'd be fail since kallsyms
dso with a same build-id was already added by perf record.

So one needs to remove the kallsyms first to add vmlinux into the cache.
Add --update option for doing it at once.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-5-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-buildid-cache.txt

@@ -27,6 +27,10 @@ OPTIONS
 -M::
 --missing=:: 
 	List missing build ids in the cache for the specified file.
+-u::
+--update::
+	Update specified file of the cache. It can be used to update kallsyms
+	kernel dso to vmlinux in order to support annotation.
 -v::
 --verbose::
 	Be more verbose.

tools/perf/builtin-buildid-cache.c

@@ -93,6 +93,32 @@ static int build_id_cache__fprintf_missing(const char *filename, bool force, FIL
 	return 0;
 }
 
+static int build_id_cache__update_file(const char *filename,
+				       const char *debugdir)
+{
+	u8 build_id[BUILD_ID_SIZE];
+	char sbuild_id[BUILD_ID_SIZE * 2 + 1];
+
+	int err;
+
+	if (filename__read_build_id(filename, &build_id, sizeof(build_id)) < 0) {
+		pr_debug("Couldn't read a build-id in %s\n", filename);
+		return -1;
+	}
+
+	build_id__sprintf(build_id, sizeof(build_id), sbuild_id);
+	err = build_id_cache__remove_s(sbuild_id, debugdir);
+	if (!err) {
+		err = build_id_cache__add_s(sbuild_id, debugdir, filename,
+					    false, false);
+	}
+	if (verbose)
+		pr_info("Updating %s %s: %s\n", sbuild_id, filename,
+			err ? "FAIL" : "Ok");
+
+	return err;
+}
+
 int cmd_buildid_cache(int argc, const char **argv,
 		      const char *prefix __maybe_unused)
 {
@@ -103,7 +129,9 @@ int cmd_buildid_cache(int argc, const char **argv,
 	char debugdir[PATH_MAX];
 	char const *add_name_list_str = NULL,
 		   *remove_name_list_str = NULL,
-		   *missing_filename = NULL;
+		   *missing_filename = NULL,
+		   *update_name_list_str = NULL;
+
 	const struct option buildid_cache_options[] = {
 	OPT_STRING('a', "add", &add_name_list_str,
 		   "file list", "file(s) to add"),
@@ -112,6 +140,8 @@ int cmd_buildid_cache(int argc, const char **argv,
 	OPT_STRING('M', "missing", &missing_filename, "file",
 		   "to find missing build ids in the cache"),
 	OPT_BOOLEAN('f', "force", &force, "don't complain, do it"),
+	OPT_STRING('u', "update", &update_name_list_str, "file list",
+		    "file(s) to update"),
 	OPT_INCR('v', "verbose", &verbose, "be more verbose"),
 	OPT_END()
 	};
@@ -169,5 +199,23 @@ int cmd_buildid_cache(int argc, const char **argv,
 	if (missing_filename)
 		ret = build_id_cache__fprintf_missing(missing_filename, force, stdout);
 
+	if (update_name_list_str) {
+		list = strlist__new(true, update_name_list_str);
+		if (list) {
+			strlist__for_each(pos, list)
+				if (build_id_cache__update_file(pos->s, debugdir)) {
+					if (errno == ENOENT) {
+						pr_debug("%s wasn't in the cache\n",
+							 pos->s);
+						continue;
+					}
+					pr_warning("Couldn't update %s: %s\n",
+						   pos->s, strerror(errno));
+				}
+
+			strlist__delete(list);
+		}
+	}
+
 	return ret;
 }