perf machine: Add method for common kernel_map(FUNCTION) operation

And it is also a step in the direction of killing the separation of data
and text maps in map_groups.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-rrds86kb3wx5wk8v38v56gw8@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index 9dfc428..2c2b443 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -48,11 +48,17 @@
 };
 
 static inline
-struct map *machine__kernel_map(struct machine *machine, enum map_type type)
+struct map *__machine__kernel_map(struct machine *machine, enum map_type type)
 {
 	return machine->vmlinux_maps[type];
 }
 
+static inline
+struct map *machine__kernel_map(struct machine *machine)
+{
+	return __machine__kernel_map(machine, MAP__FUNCTION);
+}
+
 int machine__get_kernel_start(struct machine *machine);
 
 static inline u64 machine__kernel_start(struct machine *machine)