linux-kernel - Re: [PATCH 16/34] x86, mm: simplify get_user

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Date:	Tue, 8 Dec 2015 10:30:38 -0800
From:	Dave Hansen <dave@...1.net>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
	dave.hansen@...ux.intel.com
Subject: Re: [PATCH 16/34] x86, mm: simplify get_user_pages() PTE bit handling

On 12/08/2015 10:01 AM, Thomas Gleixner wrote:
> static inline int pte_allows_gup(unsigned long pteval, int write)
> {
> 	unsigned long mask = _PAGE_PRESENT|_PAGE_USER;
> 
> 	if (write)
> 		mask |= _PAGE_RW;
> 
> 	if ((pteval & mask) != mask)
> 		return 0;
> 
> 	if (!__pkru_allows_pkey(pte_flags_pkey(pteval), write))
> 	   	return 0;
> 	return 1;
> }
> 
> and at the callsites do:
> 
>     if (pte_allows_gup(pte_val(pte, write))
> 
>     if (pte_allows_gup(pmd_val(pmd, write))
> 
>     if (pte_allows_gup(pud_val(pud, write))
> 
> Hmm?

Looks fine to me.  I'll do that.
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