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Date:   Wed, 22 May 2019 12:56:53 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Andrey Konovalov <andreyknvl@google.com>
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Subject: Re: [PATCH v15 07/17] mm, arm64: untag user pointers in mm/gup.c
Message-ID: <20190522115652.nf2r5j6xydywmccw@mbp>
References: <cover.1557160186.git.andreyknvl@google.com>
 <d234cd71774f35229bdfc0a793c34d6712b73093.1557160186.git.andreyknvl@google.com>
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On Mon, May 06, 2019 at 06:30:53PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> mm/gup.c provides a kernel interface that accepts user addresses and
> manipulates user pages directly (for example get_user_pages, that is used
> by the futex syscall). Since a user can provided tagged addresses, we need
> to handle this case.
> 
> Add untagging to gup.c functions that use user addresses for vma lookups.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

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