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authorGustavo A. R. Silva <gustavoars@kernel.org>2021-11-14 01:57:25 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2021-11-14 22:27:30 +0100
commitdee2b702bcf067d7b6b62c18bdd060ff0810a800 (patch)
tree53daf07f8ded4a59038ee0265bcc3f094a6e43b8 /Makefile
parentMerge tag 'xfs-5.16-merge-5' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux (diff)
downloadlinux-dee2b702bcf067d7b6b62c18bdd060ff0810a800.tar.xz
linux-dee2b702bcf067d7b6b62c18bdd060ff0810a800.zip
kconfig: Add support for -Wimplicit-fallthrough
Add Kconfig support for -Wimplicit-fallthrough for both GCC and Clang. The compiler option is under configuration CC_IMPLICIT_FALLTHROUGH, which is enabled by default. Special thanks to Nathan Chancellor who fixed the Clang bug[1][2]. This bugfix only appears in Clang 14.0.0, so older versions still contain the bug and -Wimplicit-fallthrough won't be enabled for them, for now. This concludes a long journey and now we are finally getting rid of the unintentional fallthrough bug-class in the kernel, entirely. :) Link: https://github.com/llvm/llvm-project/commit/9ed4a94d6451046a51ef393cd62f00710820a7e8 [1] Link: https://bugs.llvm.org/show_bug.cgi?id=51094 [2] Link: https://github.com/KSPP/linux/issues/115 Link: https://github.com/ClangBuiltLinux/linux/issues/236 Co-developed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile6
1 files changed, 1 insertions, 5 deletions
diff --git a/Makefile b/Makefile
index d83d72c26aaa..9cf9d5c1ed8f 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)
+KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
ifdef CONFIG_CC_IS_CLANG
KBUILD_CPPFLAGS += -Qunused-arguments
@@ -801,10 +801,6 @@ KBUILD_CFLAGS += -Wno-gnu
KBUILD_CFLAGS += -mno-global-merge
else
-# Warn about unmarked fall-throughs in switch statement.
-# Disabled for clang while comment to attribute conversion happens and
-# https://github.com/ClangBuiltLinux/linux/issues/636 is discussed.
-KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough=5,)
# gcc inanely warns about local variables called 'main'
KBUILD_CFLAGS += -Wno-main
endif