From: Will Deacon <will@kernel.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Yuan Li <lydorazoe@gmail.com>,
catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org,
twd2.me@gmail.com
Subject: Re: [PATCH] ARM64: Provide the ARM64_TBI option
Date: Thu, 15 Jul 2021 17:11:24 +0100 [thread overview]
Message-ID: <20210715161124.GA1330@willie-the-truck> (raw)
In-Reply-To: <854a541f-0156-2465-b640-47c0d065f87f@arm.com>
On Wed, Jul 14, 2021 at 07:43:03PM +0100, Robin Murphy wrote:
> On 2021-07-14 19:06, Yuan Li wrote:
> > The ARM64 provides the Top Byte Ignore (TBI) early on, so the kernel turns TBI
> > on by default, but, it does not provide any option to turn the feature off.
> >
> > In ARMv8.3, the Pointer Authentication (PA) was introduced, and if TBI is
> > turned off, the PA will be able to use the top byte, resulting longer pointer
> > authentication codes, which is more secure.
> >
> > This patch changes the default support for the TBI to an option that can be
> > turned off.
>
> This would have to be something that processes explicitly opt in to. See
> Documentation/arm64/tagged-pointers.rst - silently disabling TBI0 *will*
> break existing userspace software.
Maybe the patch from Peter:
https://lore.kernel.org/r/20210622051204.3682580-1-pcc@google.com
is a better starting point?
Will
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next prev parent reply other threads:[~2021-07-15 16:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 18:06 [PATCH] ARM64: Provide the ARM64_TBI option Yuan Li
2021-07-14 18:43 ` Robin Murphy
2021-07-15 16:11 ` Will Deacon [this message]
2021-07-15 16:48 ` Robin Murphy
2021-07-16 16:14 ` Peter Collingbourne
2021-07-16 16:48 ` Robin Murphy
2021-07-16 18:37 ` twd2
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