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Date: Tue, 8 Dec 2015 19:29:10 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave@sr71.net>
cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org,
        dave.hansen@linux.intel.com
Subject: Re: [PATCH 10/34] x86, pkeys: arch-specific protection bitsy
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On Tue, 8 Dec 2015, Dave Hansen wrote:

> Here's how it looks with the suggested modifications.
> 
> Whatever compiler wonkiness I was seeing is gone now, so I've used the
> most straightforward version of the shifts.

> +        * gcc generates better code if we do this rather than:
> +        * pkey = (flags & mask) >> shift
> +        */
> +       pkey = (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;

ROTFL!