[PATCH v10 13/13] arm64: BTI: Add Kconfig entry for userspace BTI
From: Mark Brown <broonie@kernel.org>
Date: 2020-03-16 16:51:35
Also in:
linux-arch, linux-fsdevel, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
From: Dave Martin <Dave.Martin@arm.com>
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: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Kees Cook <redacted>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/Kconfig | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 8a15bc68dadd..d65d226a77ec 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
--
2.20.1
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