From: Dave Martin Date: Mon, 16 Mar 2020 16:50:55 +0000 (+0000) Subject: arm64: BTI: Add Kconfig entry for userspace BTI X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=383499f8863ea8ce869ba62cec91d9f709c9459b;p=linux.git arm64: BTI: Add Kconfig entry for userspace BTI Now that the code for userspace BTI support is in the kernel add the Kconfig entry so that it can be built and used. [Split out of "arm64: Basic Branch Target Identification support" -- broonie] Signed-off-by: Mark Brown Signed-off-by: Dave Martin Reviewed-by: Kees Cook Signed-off-by: Catalin Marinas --- diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 8a15bc68dadd9..d65d226a77ec6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1522,6 +1522,28 @@ endmenu menu "ARMv8.5 architectural features" +config ARM64_BTI + bool "Branch Target Identification support" + default y + help + Branch Target Identification (part of the ARMv8.5 Extensions) + provides a mechanism to limit the set of locations to which computed + branch instructions such as BR or BLR can jump. + + To make use of BTI on CPUs that support it, say Y. + + BTI is intended to provide complementary protection to other control + flow integrity protection mechanisms, such as the Pointer + authentication mechanism provided as part of the ARMv8.3 Extensions. + For this reason, it does not make sense to enable this option without + also enabling support for pointer authentication. Thus, when + enabling this option you should also select ARM64_PTR_AUTH=y. + + Userspace binaries must also be specifically compiled to make use of + this mechanism. If you say N here or the hardware does not support + BTI, such binaries can still run, but you get no additional + enforcement of branch destinations. + config ARM64_E0PD bool "Enable support for E0PD" default y