Re: [PATCH v2 5/5] arm64: add KASan support

From: Will Deacon
Date: Tue Aug 25 2015 - 05:16:04 EST

On Mon, Aug 24, 2015 at 06:47:36PM +0100, Russell King - ARM Linux wrote:
> On Mon, Aug 24, 2015 at 05:15:22PM +0300, Andrey Ryabinin wrote:
> > Yes, ~130Mb (3G/1G split) should work. 512Mb shadow is optional.
> > The only advantage of 512Mb shadow is better handling of user memory
> > accesses bugs
> > (access to user memory without copy_from_user/copy_to_user/strlen_user etc API).
> No need for that to be handed by KASan. I have patches in linux-next,
> now acked by Will, which prevent the kernel accessing userspace with
> zero memory footprint. No need for remapping, we have a way to quickly
> turn off access to userspace mapped pages on non-LPAE 32-bit CPUs.
> (LPAE is not supported yet - Catalin will be working on that using the
> hooks I'm providing once he returns.)

Hey, I only acked the "Efficiency cleanups" series so far! The PAN emulation
is still on my list.

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