linux-kernel - Re: powerpc/nohash: fix pte_access

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Message-Id: <41x63533G3z9s5b@ozlabs.org>
Date:   Fri, 24 Aug 2018 00:18:40 +1000 (AEST)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        aneesh.kumar@...ux.vnet.ibm.com
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: powerpc/nohash: fix pte_access_permitted()

On Tue, 2018-08-21 at 13:03:23 UTC, Christophe Leroy wrote:
> Commit 5769beaf180a8 ("powerpc/mm: Add proper pte access check helper
> for other platforms") replaced generic pte_access_permitted() by an
> arch specific one.
> 
> The generic one is defined as
> (pte_present(pte) && (!(write) || pte_write(pte)))
> 
> The arch specific one is open coded checking that _PAGE_USER and
> _PAGE_WRITE (_PAGE_RW) flags are set, but lacking to check that
> _PAGE_RO and _PAGE_PRIVILEGED are unset, leading to a useless test
> on targets like the 8xx which defines _PAGE_RW and _PAGE_USER as 0.
> 
> Commit 5fa5b16be5b31 ("powerpc/mm/hugetlb: Use pte_access_permitted
> for hugetlb access check") replaced some tests performed with
> pte helpers by a call to pte_access_permitted(), leading to the same
> issue.
> 
> This patch rewrites powerpc/nohash pte_access_permitted()
> using pte helpers.
> 
> Fixes: 5769beaf180a8 ("powerpc/mm: Add proper pte access check helper for other platforms")
> Fixes: 5fa5b16be5b31 ("powerpc/mm/hugetlb: Use pte_access_permitted for hugetlb access check")
> Cc: stable@...r.kernel.org # v4.15+
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/810e9f86f36f59f1d6f6710220c49a

cheers