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Date: Fri, 28 Oct 2016 12:11:46 +0100
From: Mark Rutland <mark.rutland@arm.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Laura Abbott <labbott@redhat.com>, Will Deacon <will.deacon@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
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Subject: Re: [RFC][PATCH] arm64: Add support for CONFIG_DEBUG_VIRTUAL
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On Fri, Oct 28, 2016 at 08:52:50AM +0100, Ard Biesheuvel wrote:
> Hi Laura,
> 
> On 28 October 2016 at 01:18, Laura Abbott <labbott@redhat.com> wrote:
> > x86 has an option CONFIG_DEBUG_VIRTUAL to do additional checks
> > on virt_to_phys calls. The goal is to catch users who are calling
> > virt_to_phys on non-linear addresses immediately. As features
> > such as CONFIG_VMAP_STACK get enabled for arm64, this becomes
> > increasingly important. Add checks to catch bad virt_to_phys
> > usage.
> 
> I think this is a useful thing to have. However, the Kconfig
> description talks about virt to page translations, not virt to phys.
> Of course, this is a shift away from being equivalent on x86, but not
> so much on arm64. Any concerns there?

See commit 59ea746337c69f6a ("MM: virtual address debug"); the existing
x86 cases cover virt to phys also.

The Kconfig text does say "and friends"...

Thanks,
Mark.