perf kmem: Resolve kernel symbols again

Due to the assumption in perf_session__new that the kernel maps would be
created using the fake PERF_RECORD_MMAP event in a perf.data file 'perf
kmem --stat caller', that doesn't have such event, ends up not being
able to resolve the kernel addresses.

Fix it by calling perf_session__create_kernel_maps() in __cmd_kmem().

LKML-Reference: <new-submission>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-kmem.c

@@ -489,6 +489,9 @@ static int __cmd_kmem(void)
 	if (session == NULL)
 		return -ENOMEM;
 
+	if (perf_session__create_kernel_maps(session) < 0)
+		goto out_delete;
+
 	if (!perf_session__has_traces(session, "kmem record"))
 		goto out_delete;
 

tools/perf/util/session.c

@@ -52,11 +52,6 @@ static int perf_session__open(struct perf_session *self, bool force)
 	return -1;
 }
 
-static inline int perf_session__create_kernel_maps(struct perf_session *self)
-{
-	return map_groups__create_kernel_maps(&self->kmaps, self->vmlinux_maps);
-}
-
 struct perf_session *perf_session__new(const char *filename, int mode, bool force)
 {
 	size_t len = filename ? strlen(filename) + 1 : 0;

tools/perf/util/session.h

@@ -80,6 +80,11 @@ static inline int __perf_session__create_kernel_maps(struct perf_session *self,
 						self->vmlinux_maps, kernel);
 }
 
+static inline int perf_session__create_kernel_maps(struct perf_session *self)
+{
+	return map_groups__create_kernel_maps(&self->kmaps, self->vmlinux_maps);
+}
+
 static inline struct map *
 	perf_session__new_module_map(struct perf_session *self,
 				     u64 start, const char *filename)