From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Subject: arm64: enable armv8.5-a asm-arch option Hardware tag-based KASAN relies on Memory Tagging Extension (MTE) which is an armv8.5-a architecture extension. Enable the correct asm option when the compiler supports it in order to allow the usage of ALTERNATIVE()s with MTE instructions. Link: https://lkml.kernel.org/r/d03d1157124ea3532eaeb77507988733f5734986.1606161801.git.andreyknvl@xxxxxxxxxx Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx> Tested-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx> Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm64/Kconfig | 4 ++++ arch/arm64/Makefile | 5 +++++ 2 files changed, 9 insertions(+) --- a/arch/arm64/Kconfig~arm64-enable-armv85-a-asm-arch-option +++ a/arch/arm64/Kconfig @@ -1571,6 +1571,9 @@ endmenu menu "ARMv8.5 architectural features" +config AS_HAS_ARMV8_5 + def_bool $(cc-option,-Wa$(comma)-march=armv8.5-a) + config ARM64_BTI bool "Branch Target Identification support" default y @@ -1645,6 +1648,7 @@ config ARM64_MTE bool "Memory Tagging Extension support" default y depends on ARM64_AS_HAS_MTE && ARM64_TAGGED_ADDR_ABI + depends on AS_HAS_ARMV8_5 select ARCH_USES_HIGH_VMA_FLAGS help Memory Tagging (part of the ARMv8.5 Extensions) provides --- a/arch/arm64/Makefile~arm64-enable-armv85-a-asm-arch-option +++ a/arch/arm64/Makefile @@ -96,6 +96,11 @@ ifeq ($(CONFIG_AS_HAS_ARMV8_4), y) asm-arch := armv8.4-a endif +ifeq ($(CONFIG_AS_HAS_ARMV8_5), y) +# make sure to pass the newest target architecture to -march. +asm-arch := armv8.5-a +endif + ifdef asm-arch KBUILD_CFLAGS += -Wa,-march=$(asm-arch) \ -DARM64_ASM_ARCH='"$(asm-arch)"' _
