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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 <broonie@kernel.org>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
alistair/sunxi64-5.8
Dave Martin 2020-03-16 16:50:55 +00:00 committed by Catalin Marinas
parent 424037b775
commit 383499f886
1 changed files with 22 additions and 0 deletions
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arch/arm64/Kconfig
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@ -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