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From: Pavel Tatashin <pasha.tatashin@oracle.com>
Date: Mon, 9 Oct 2017 15:07:01 -0400
Message-ID: <CAOAebxvcg9r00bCWDJS4V_mmKk_dELVs_SfxqrxemDg7=uZx_g@mail.gmail.com>
Subject: Re: [PATCH v9 09/12] mm/kasan: kasan specific map populate function
To: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>, catalin.marinas@arm.com,
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>
> Ok, but I'm still missing why you think that is needed. What would be the
> second page table walker that needs implementing?
>
> I guess we could implement that on arm64 using our current vmemmap_populate
> logic and an explicit memset.
>

Hi Will,

What do you mean by explicit memset()? We can't simply memset() from
start to end without doing the page table walk, because at the time
kasan is calling vmemmap_populate() we have a tmp_pg_dir instead of
swapper_pg_dir.

We could do the explicit memset() after
cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); but again, this was in
one of my previous implementations, and I was asked to replace that.

Pavel