This patch adds CONFIG_HARDEN_SLS_ALL that can be used to turn on -mharden-sls=all, which mitigates the straight-line speculation vulnerability, speculative execution of the instruction following some unconditional jumps. Notice -mharden-sls= has other options as below, and this config turns on the strongest option.
all: enable all mitigations against Straight Line Speculation that are implemented. none: disable all mitigations against Straight Line Speculation. retbr: enable the mitigation against Straight Line Speculation for RET and BR instructions. blr: enable the mitigation against Straight Line Speculation for BLR instructions. Link: https://reviews.llvm.org/D93221 Link: https://reviews.llvm.org/D81404 Link: https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/downloads/straight-line-speculation https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/frequently-asked-questions#SLS2 Suggested-by: Manoj Gupta <[email protected]> Suggested-by: Nathan Chancellor <[email protected]> Suggested-by: David Laight <[email protected]> Signed-off-by: Jian Cai <[email protected]> --- Changes v1 -> v2: Update the description and patch based on Nathan and David's comments. arch/arm/Makefile | 4 ++++ arch/arm64/Makefile | 4 ++++ security/Kconfig.hardening | 7 +++++++ 3 files changed, 15 insertions(+) diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 4aaec9599e8a..11d89ef32da9 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -48,6 +48,10 @@ CHECKFLAGS += -D__ARMEL__ KBUILD_LDFLAGS += -EL endif +ifeq ($(CONFIG_HARDEN_SLS_ALL), y) +KBUILD_CFLAGS += -mharden-sls=all +endif + # # The Scalar Replacement of Aggregates (SRA) optimization pass in GCC 4.9 and # later may result in code being generated that handles signed short and signed diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 90309208bb28..ca7299b356a9 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -34,6 +34,10 @@ $(warning LSE atomics not supported by binutils) endif endif +ifeq ($(CONFIG_HARDEN_SLS_ALL), y) +KBUILD_CFLAGS += -mharden-sls=all +endif + cc_has_k_constraint := $(call try-run,echo \ 'int main(void) { \ asm volatile("and w0, w0, %w0" :: "K" (4294967295)); \ diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index 269967c4fc1b..9266d8d1f78f 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -121,6 +121,13 @@ choice endchoice +config HARDEN_SLS_ALL + bool "enable SLS vulnerability hardening" + def_bool $(cc-option,-mharden-sls=all) + help + Enables straight-line speculation vulnerability hardening + at highest level. + config GCC_PLUGIN_STRUCTLEAK_VERBOSE bool "Report forcefully initialized variables" depends on GCC_PLUGIN_STRUCTLEAK -- 2.30.0.478.g8a0d178c01-goog
