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arm64: Add skeleton to harden the branch predictor against aliasing attacks

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Aliasing attacks against CPU branch predictors can allow an attacker to
redirect speculative control flow on some CPUs and potentially divulge
information from one context to another.

This patch adds initial skeleton code behind a new Kconfig option to
enable implementation-specific mitigations against these attacks for
CPUs that are affected.

Co-developed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon
2018-01-03 11:17:58 +00:00
committed by Catalin Marinas
parent 95e3de3590
commit 0f15adbb28
11 changed files with 215 additions and 3 deletions
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17
arch/arm64/Kconfig
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@@ -874,6 +874,23 @@ config UNMAP_KERNEL_AT_EL0
If unsure, say Y.
config HARDEN_BRANCH_PREDICTOR
bool "Harden the branch predictor against aliasing attacks" if EXPERT
default y
help
Speculation attacks against some high-performance processors rely on
being able to manipulate the branch predictor for a victim context by
executing aliasing branches in the attacker context. Such attacks
can be partially mitigated against by clearing internal branch
predictor state and limiting the prediction logic in some situations.
This config option will take CPU-specific actions to harden the
branch predictor against aliasing attacks and may rely on specific
instruction sequences or control bits being set by the system
firmware.
If unsure, say Y.
menuconfig ARMV8_DEPRECATED
bool "Emulate deprecated/obsolete ARMv8 instructions"
depends on COMPAT