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SubjectRe: [PATCH v5] arm64: Add workaround for Fujitsu A64FX erratum 010001
On Tue, Feb 26, 2019 at 06:43:41PM +0000, James Morse wrote:
> From: Zhang Lei <zhang.lei@jp.fujitsu.com>
>
> On the Fujitsu-A64FX cores ver(1.0, 1.1), memory access may cause
> an undefined fault (Data abort, DFSC=0b111111). This fault occurs under
> a specific hardware condition when a load/store instruction performs an
> address translation. Any load/store instruction, except non-fault access
> including Armv8 and SVE might cause this undefined fault.
>
> The TCR_ELx.NFD1 bit is used by the kernel when CONFIG_RANDOMIZE_BASE
> is enabled to mitigate timing attacks against KASLR where the kernel
> address space could be probed using the FFR and suppressed fault on
> SVE loads.
>
> Since this erratum causes spurious exceptions, which may corrupt
> the exception registers, we clear the TCR_ELx.NFDx=1 bits when
> booting on an affected CPU.
>
> Signed-off-by: Zhang Lei <zhang.lei@jp.fujitsu.com>
> [Generated MIDR value/mask for __cpu_setup(), removed spurious-fault handler
> and always disabled the NFDx bits on affected CPUs]
> Signed-off-by: James Morse <james.morse@arm.com>
> Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>

Queued for 5.1. Thanks.

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