From: Mark Brown <broonie@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: bti: Fix support for userspace only BTI
Date: Tue, 12 May 2020 12:05:02 +0100 [thread overview]
Message-ID: <20200512110502.GC5110@sirena.org.uk> (raw)
In-Reply-To: <20200512103908.GB3021@willie-the-truck>
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On Tue, May 12, 2020 at 11:39:09AM +0100, Will Deacon wrote:
> Might be worth a comment here in case somebody tries to "clean this up"
> later on!
> > +#ifdef CONFIG_ARM64_BTI_KERNEL
> > #define PTE_MAYBE_GP (system_supports_bti() ? PTE_GP : 0)
> > +#else
> > +#define PTE_MAYBE_GP 0
> > +#endif
Sure.
> I also notice we have a funny check in the vdso code:
> if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) && system_supports_bti())
> but why do we care about CONFIG_ARM64_BTI_KERNEL for the vdso pages?
To enable BTI for the vDSO we need the vDSO to be built with BTI
annotations. Currently the CFLAGS are the same for the vDSO and the
kernel, we could arrange to allow them to differ but since the most
likely reason why the user has userspace but not kernel BTI is that
their compiler isn't suitable it seemed like disproportionate effort
for a most likely small audience.
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next prev parent reply other threads:[~2020-05-12 11:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 9:21 [PATCH] arm64: bti: Fix support for userspace only BTI Mark Brown
2020-05-12 10:39 ` Will Deacon
2020-05-12 11:05 ` Mark Brown [this message]
2020-05-12 11:42 ` Will Deacon
2020-05-13 14:46 ` Dave Martin
2020-05-13 15:08 ` Mark Brown
2020-05-13 16:49 ` Dave Martin
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