arm64: bti: Support building kernel C code using BTI (92e2294d) · Commits · 戴 / test

When running with BTI enabled we need to ask the compiler to enable generation of BTI landing pads beyond those generated as a result of pointer authentication instructions being landing pads. Since the two features are practically speaking unlikely to be used separately we will make kernel mode BTI depend on pointer authentication in order to simplify the Makefile. Signed-off-by:

Mark Brown <broonie@kernel.org> Reviewed-by:

Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20200506195138.22086-3-broonie@kernel.org Signed-off-by:

Will Deacon <will@kernel.org>

arch/arm64/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -74,7 +74,11 @@ branch-prot-flags-$(CONFIG_CC_HAS_SIGN_RETURN_ADDRESS) := -msign-return-address=
		# We enable additional protection for leaf functions as there is some
		# narrow potential for ROP protection benefits and no substantial
		# performance impact has been observed.
		ifeq ($(CONFIG_ARM64_BTI_KERNEL),y)
		branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET_BTI) := -mbranch-protection=pac-ret+leaf+bti
		else
		branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=pac-ret+leaf
		endif
		# -march=armv8.3-a enables the non-nops instructions for PAC, to avoid the
		# compiler to generate them and consequently to break the single image contract
		# we pass it only to the assembler. This option is utilized only in case of non

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