linux-hardening - [PATCH v6 kspp-next 02/22] kbuild: merge vmlinux_link() between the ordinary link and Clang LTO

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Date:   Tue, 31 Aug 2021 16:40:54 +0200
From:   Alexander Lobakin <alexandr.lobakin@...el.com>
To:     linux-hardening@...r.kernel.org
Cc:     "Kristen C Accardi" <kristen.c.accardi@...el.com>,
        Kristen Carlson Accardi <kristen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Jessica Yu <jeyu@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Marios Pomonis <pomonis@...gle.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Tony Luck <tony.luck@...el.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Lukasz Czapnik <lukasz.czapnik@...el.com>,
        "Marta A Plantykow" <marta.a.plantykow@...el.com>,
        Michal Kubiak <michal.kubiak@...el.com>,
        Michal Swiatkowski <michal.swiatkowski@...el.com>,
        Alexander Lobakin <alexandr.lobakin@...el.com>,
        linux-kbuild@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: [PATCH v6 kspp-next 02/22] kbuild: merge vmlinux_link() between the ordinary link and Clang LTO

From: Masahiro Yamada <masahiroy@...nel.org>

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@...nel.org>
Reviewed-by: Kees Cook <keescook@...omium.org>
---
 scripts/link-vmlinux.sh | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 36ef7b37fc5d..a6c4d0bce3ba 100755
--- a/scripts/link-vmlinux.sh
+++ b/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
-			# Use vmlinux.o instead of performing the slow LTO
-			# 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
+		objects="--whole-archive ${objs} --no-whole-archive	\
+			 --start-group ${libs} --end-group		\
+			 $@"
 
 		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}	\
 			${strip_debug#-Wl,}			\
-- 
2.31.1