arm64: kaslr: Set TCR_EL1.NFD1 when CONFIG_RANDOMIZE_BASE=y
authorWill Deacon <will.deacon@arm.com>
Tue, 27 Feb 2018 14:15:49 +0000 (14:15 +0000)
committerWill Deacon <will.deacon@arm.com>
Tue, 6 Mar 2018 18:52:34 +0000 (18:52 +0000)
commite03e61c3173c1079058920210ab40c458a0e0899
tree87320513202327ecf803cea18a5afe1d366bba1f
parent24153c03d4f5dc4ac0ccd446a9636c269c1d4a02
arm64: kaslr: Set TCR_EL1.NFD1 when CONFIG_RANDOMIZE_BASE=y

TCR_EL1.NFD1 was allocated by SVE and ensures that fault-surpressing SVE
memory accesses (e.g. speculative accesses from a first-fault gather load)
which translate via TTBR1_EL1 result in a translation fault if they
miss in the TLB when executed from EL0. This mitigates some timing attacks
against KASLR, where the kernel address space could otherwise be probed
efficiently using the FFR in conjunction with suppressed faults on SVE
loads.

Cc: Dave Martin <Dave.Martin@arm.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
arch/arm64/include/asm/pgtable-hwdef.h
arch/arm64/mm/proc.S