From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <Mark.Rutland@arm.com>,
Kees Cook <keescook@chromium.org>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
Amit Kachhap <Amit.Kachhap@arm.com>,
Will Deacon <will@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm64: Always force a branch protection mode when the compiler has one
Date: Wed, 1 Apr 2020 19:07:21 +0100 [thread overview]
Message-ID: <20200401180721.GG4943@sirena.org.uk> (raw)
In-Reply-To: <20200401175444.GF9434@mbp>
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On Wed, Apr 01, 2020 at 06:54:44PM +0100, Catalin Marinas wrote:
> On Tue, Mar 31, 2020 at 08:44:59PM +0100, Mark Brown wrote:
> > Compilers with branch protection support can be configured to enable it by
> > default, it is likely that distributions will do this as part of deploying
> > branch protection system wide. As well as the slight overhead from having
> > some extra NOPs for unused branch protection features this can cause more
> > serious problems when the kernel is providing pointer authentication to
> > userspace but not built for pointer authentication itself.
> With 5.7 you won't be able to configure user and kernel PAC support
> independently. So, I guess that's something only for prior kernel
> versions.
Yes, it's really for the benefit of stable at this point - hence the Cc.
Going forward it's hopefully more for defensiveness than anything else,
it's possible something similar might come up with some future stuff but
ideally not.
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prev parent reply other threads:[~2020-04-01 18:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-31 19:44 [PATCH] arm64: Always force a branch protection mode when the compiler has one Mark Brown
2020-03-31 19:46 ` Kees Cook
2020-04-01 9:55 ` Mark Rutland
2020-04-01 17:54 ` Catalin Marinas
2020-04-01 18:07 ` Mark Brown [this message]
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