From cd8c917a56f20f48748dd43d9ae3caff51d5b987 Mon Sep 17 00:00:00 2001
From: Salvatore Bonaccorso <carnil@debian.org>
Date: Mon, 6 Dec 2021 21:42:01 +0100
Subject: [PATCH] Makefile: Do not quote value for
 CONFIG_CC_IMPLICIT_FALLTHROUGH

Andreas reported that a specific build environment for an external
module, being a bit broken, does pass CC_IMPLICIT_FALLTHROUGH quoted as
argument to gcc, causing an error

  gcc-11: error: "-Wimplicit-fallthrough=5": linker input file not found: No such file or directory

Until this is more generally fixed as outlined in [1], by fixing
scripts/link-vmlinux.sh, scripts/gen_autoksyms.sh, etc to not directly
include the include/config/auto.conf, and in a second step, change
Kconfig to generate the auto.conf without "", workaround the issue by
explicitly unquoting CC_IMPLICIT_FALLTHROUGH.

Reported-by: Andreas Beckmann <anbe@debian.org>
Link: https://bugs.debian.org/1001083
Link: https://lore.kernel.org/linux-kbuild/CAK7LNAR-VXwHFEJqCcrFDZj+_4+Xd6oynbj_0eS8N504_ydmyw@mail.gmail.com/ [1]
Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 8e35d7804fef4..ef967a26bcd39 100644
--- a/Makefile
+++ b/Makefile
@@ -789,7 +789,7 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG)      := -fstack-protector-strong
 KBUILD_CFLAGS += $(stackp-flags-y)
 
 KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror
-KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
+KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH:"%"=%)
 
 ifdef CONFIG_CC_IS_CLANG
 KBUILD_CPPFLAGS += -Qunused-arguments
-- 
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