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x86/retpolines: Fix up backport of a9d57ef15c

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Commit a9d57ef15c ("x86/retpolines: Disable switch jump tables when
retpolines are enabled") added -fno-jump-tables to workaround a GCC issue
while deliberately avoiding adding this flag when CONFIG_CC_IS_CLANG is
set, which is defined by the kconfig system when CC=clang is provided.

However, this symbol was added in 4.18 in commit 469cb7376c ("kconfig:
add CC_IS_CLANG and CLANG_VERSION") so it is always undefined in 4.14,
meaning -fno-jump-tables gets added when using Clang.

Fix this up by using the equivalent $(cc-name) comparison, which matches
what upstream did until commit 076f421da5 ("kbuild: replace cc-name
test with CONFIG_CC_IS_CLANG").

Fixes: e289511005 ("x86/retpolines: Disable switch jump tables when retpolines are enabled")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nathan Chancellor 2019-09-29 11:32:06 -07:00 committed by Greg Kroah-Hartman
parent 2d76dd0e17
commit 32c2a4de71
1 changed files with 1 additions and 1 deletions
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2
arch/x86/Makefile
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@ -249,7 +249,7 @@ ifdef CONFIG_RETPOLINE
# retpoline builds, however, gcc does not for x86. This has
# only been fixed starting from gcc stable version 8.4.0 and
# onwards, but not for older ones. See gcc bug #86952.
ifndef CONFIG_CC_IS_CLANG
ifneq ($(cc-name), clang)
KBUILD_CFLAGS += $(call cc-option,-fno-jump-tables)
endif
endif