From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: broonie@kernel.org, catalin.marinas@arm.com, will@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/2] arm64: Add initial support for E0PD
Date: Tue, 13 Aug 2019 10:59:59 +0100 [thread overview]
Message-ID: <0e5014d6-83b0-36df-ce6e-f491edffd4f9@arm.com> (raw)
In-Reply-To: <20190812125738.17388-2-broonie@kernel.org>
On 12/08/2019 13:57, Mark Brown wrote:
> Kernel Page Table Isolation (KPTI) is used to mitigate some speculation
> based security issues by ensuring that the kernel is not mapped when
> userspace is running but this approach is expensive and is incompatible
> with SPE. E0PD, introduced in the ARMv8.5 extensions, provides an
> alternative to this which ensures that accesses from userspace to the
> kernel's half of the memory map to always fault with constant time,
> preventing timing attacks without requiring constant unmapping and
> remapping or preventing legitimate accesses.
>
> This initial patch does not yet integrate with KPTI, this will be dealt
> with in followup patches. Ideally we could ensure that by default we
> don't use KPTI on CPUs where E0PD is present.
>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> arch/arm64/Kconfig | 14 +++++++++++++
> arch/arm64/include/asm/cpucaps.h | 3 ++-
> arch/arm64/include/asm/pgtable-hwdef.h | 2 ++
> arch/arm64/include/asm/sysreg.h | 1 +
> arch/arm64/kernel/cpufeature.c | 27 ++++++++++++++++++++++++++
> 5 files changed, 46 insertions(+), 1 deletion(-)
>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
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next prev parent reply other threads:[~2019-08-13 10:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-12 12:57 [0/2] arm64: E0PD support Mark Brown
2019-08-12 12:57 ` [PATCH 1/2] arm64: Add initial support for E0PD Mark Brown
2019-08-13 9:59 ` Suzuki K Poulose [this message]
2019-08-13 17:25 ` Will Deacon
2019-08-12 12:57 ` [PATCH 2/2] arm64: Don't use KPTI where we have E0PD Mark Brown
2019-08-13 10:01 ` Suzuki K Poulose
2019-08-13 17:28 ` Will Deacon
2019-08-13 19:05 ` Mark Brown
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