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Date: Mon, 1 Jul 2019 10:44:17 +0100
From: Catalin Marinas <catalin.marinas@arm.com>
To: Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH v2 1/3] arm64: mm: Add p?d_large() definitions
Message-ID: <20190701094417.GB21774@arrakis.emea.arm.com>
References: <20190701064026.970-1-npiggin@gmail.com>
 <20190701064026.970-2-npiggin@gmail.com>
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Cc: Mark Rutland <mark.rutland@arm.com>,
 Anshuman Khandual <anshuman.khandual@arm.com>,
 Ard Biesheuvel <ard.biesheuvel@linaro.org>, Will Deacon <will.deacon@arm.com>,
 Steven Price <steven.price@arm.com>,
 "linux-mm @ kvack . org" <linux-mm@kvack.org>,
 Andrew Morton <akpm@linux-foundation.org>,
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 "linux-arm-kernel @ lists . infradead . org"
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On Mon, Jul 01, 2019 at 04:40:24PM +1000, Nicholas Piggin wrote:
> walk_page_range() is going to be allowed to walk page tables other than
> those of user space. For this it needs to know when it has reached a
> 'leaf' entry in the page tables. This information will be provided by the
> p?d_large() functions/macros.
> 
> For arm64, we already have p?d_sect() macros which we can reuse for
> p?d_large().
> 
> pud_sect() is defined as a dummy function when CONFIG_PGTABLE_LEVELS < 3
> or CONFIG_ARM64_64K_PAGES is defined. However when the kernel is
> configured this way then architecturally it isn't allowed to have a
> large page that this level, and any code using these page walking macros
> is implicitly relying on the page size/number of levels being the same as
> the kernel. So it is safe to reuse this for p?d_large() as it is an
> architectural restriction.
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Steven Price <steven.price@arm.com>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>