powerpc/nohash: fix pte_access_permitted()

[Michael Ellerman]

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 at vger.kernel.org # v4.15+
> Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>

Applied to powerpc next, thanks.

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

cheers