diff options
Diffstat (limited to 'arch/x86/Makefile')
| -rw-r--r-- | arch/x86/Makefile | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index c5290aecdf06..3dc54d2f79c4 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -39,6 +39,7 @@ REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -D__KERNEL__ \ REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding) REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -fno-stack-protector) +REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member) REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4)) export REALMODE_CFLAGS @@ -48,7 +49,7 @@ export REALMODE_CFLAGS export BITS ifdef CONFIG_X86_NEED_RELOCS - LDFLAGS_vmlinux := --emit-relocs + LDFLAGS_vmlinux := --emit-relocs --discard-none endif # @@ -242,6 +243,15 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables # Avoid indirect branches in kernel to deal with Spectre ifdef CONFIG_RETPOLINE KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) + # Additionally, avoid generating expensive indirect jumps which + # are subject to retpolines for small number of switch cases. + # clang turns off jump table generation by default when under + # retpoline builds, however, gcc does not for x86. This has + # only been fixed starting from gcc stable version 8.4.0 and + # onwards, but not for older ones. See gcc bug #86952. + ifneq ($(cc-name), clang) + KBUILD_CFLAGS += $(call cc-option,-fno-jump-tables) + endif endif archscripts: scripts_basic |