[PATCH/RFC 9/9] perf record: Add --module-dir option

[Namhyung Kim]

Currently perf only searches module binaries on the canonical
directory (/lib/modules/`uname -r`).  But sometimes user needs to load
local modules.  These cannot be copied to the build-id cache since long
name (i.e. real path) of DSOs was not set.

This patch fixes the problem by adding a new --module-dir option so that
perf can record modules in the directory.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/Documentation/perf-record.txt |  3 +++
 tools/perf/builtin-record.c              |  2 ++
 tools/perf/util/machine.c                | 15 ++++++++++++++-
 tools/perf/util/symbol.h                 |  3 ++-
 4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index eb2f5fb90534..9030ace9010f 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -480,6 +480,9 @@ Implies --tail-synthesize.
 --use-kcore::
 Use /proc/kcore for symbols and object code reading
 
+--module-dir=PATH::
+Directory name where extra modules are located.
+
 SEE ALSO
 --------
 linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index a6a6cb56fdf5..8a67fafc0d5b 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1671,6 +1671,8 @@ static struct option __record_options[] = {
 		    "Parse options then exit"),
 	OPT_BOOLEAN(0, "use-kcore", &symbol_conf.use_kcore,
 		    "Use /proc/kcore for object code"),
+	OPT_STRING(0, "module-dir", &symbol_conf.extra_module_path, "path",
+		   "directory name where extra modules are located"),
 	OPT_END()
 };
 
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 799efe920f0c..9a18365c443a 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1108,6 +1108,7 @@ static int machine__set_modules_path(struct machine *machine)
 {
 	char *version;
 	char modules_path[PATH_MAX];
+	int ret;
 
 	version = get_kernel_version(machine->root_dir);
 	if (!version)
@@ -1117,7 +1118,19 @@ static int machine__set_modules_path(struct machine *machine)
 		 machine->root_dir, version);
 	free(version);
 
-	return map_groups__set_modules_path_dir(&machine->kmaps, modules_path, 0);
+	ret = map_groups__set_modules_path_dir(&machine->kmaps, modules_path, 0);
+	if (ret < 0)
+		return ret;
+
+	if (symbol_conf.extra_module_path) {
+		snprintf(modules_path, sizeof(modules_path), "%s/%s",
+			 machine->root_dir, symbol_conf.extra_module_path);
+
+		ret = map_groups__set_modules_path_dir(&machine->kmaps,
+						       modules_path, 0);
+	}
+
+	return ret;
 }
 int __weak arch__fix_module_text_start(u64 *start __maybe_unused,
 				const char *name __maybe_unused)
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 88361eeae813..59370ceb87c4 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -124,7 +124,8 @@ struct symbol_conf {
 	const char	*vmlinux_name,
 			*kallsyms_name,
 			*source_prefix,
-			*field_sep;
+			*field_sep,
+			*extra_module_path;
 	const char	*default_guest_vmlinux_name,
 			*default_guest_kallsyms,
 			*default_guest_modules;
-- 
2.13.1