kbuild: merge vmlinux_link() between the ordinary link and Clang LTO

When Clang LTO is enabled, vmlinux_link() reuses vmlinux.o instead of
re-linking ${KBUILD_VMLINUX_OBJS} and ${KBUILD_VMLINUX_LIBS}.

That is the only difference here, so merge the similar code.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>

scripts/link-vmlinux.sh

@@ -154,12 +154,23 @@ vmlinux_link()
 	local objects
 	local strip_debug
 	local map_option
+	local objs
+	local libs
 
 	info LD ${output}
 
 	# skip output file argument
 	shift
 
+	if [ -n "${CONFIG_LTO_CLANG}" ]; then
+		# Use vmlinux.o instead of performing the slow LTO link again.
+		objs=vmlinux.o
+		libs=
+	else
+		objs="${KBUILD_VMLINUX_OBJS}"
+		libs="${KBUILD_VMLINUX_LIBS}"
+	fi
+
 	# The kallsyms linking does not need debug symbols included.
 	if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
 		strip_debug=-Wl,--strip-debug
@@ -170,22 +181,9 @@ vmlinux_link()
 	fi
 
 	if [ "${SRCARCH}" != "um" ]; then
-		if [ -n "${CONFIG_LTO_CLANG}" ]; then
+		objects="--whole-archive ${objs} --no-whole-archive	\
-			# Use vmlinux.o instead of performing the slow LTO
+			 --start-group ${libs} --end-group		\
-			# link again.
+			 $@"
-			objects="--whole-archive		\
-				vmlinux.o 			\
-				--no-whole-archive		\
-				${@}"
-		else
-			objects="--whole-archive		\
-				${KBUILD_VMLINUX_OBJS}		\
-				--no-whole-archive		\
-				--start-group			\
-				${KBUILD_VMLINUX_LIBS}		\
-				--end-group			\
-				${@}"
-		fi
 
 		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}	\
 			${strip_debug#-Wl,}			\