powerpc/mm/subpage: Clear RWX bit to indicate no access
authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Fri, 29 Apr 2016 13:25:31 +0000 (23:25 +1000)
committerMichael Ellerman <mpe@ellerman.id.au>
Sun, 1 May 2016 08:32:23 +0000 (18:32 +1000)
commit73a1441a9b2ae05c15eb7cc90d4de379b44249bf
treef3e91025eaa84ccd36bf71bd9f5fd2e19e2c9a6a
parentc7d54842deb1fa357cff75b988275a1c9f259140
powerpc/mm/subpage: Clear RWX bit to indicate no access

Subpage protection used to depend on the _PAGE_USER bit to implement no
access mode. This patch switches that to use _PAGE_RWX. We clear Read,
Write and Execute access from the pte instead of clearing _PAGE_USER
now. This was done so that we can switch to _PAGE_PRIVILEGED in a later
patch.

subpage_protection() returns pte bits that need to be cleared. Instead
of updating the interface to handle no-access in a separate way, it
appears simpler to clear RWX acecss to indicate no access.

We still don't insert hash ptes for no access implied by !_PAGE_RWX.
Hence we should not get PROT_FAULT with change.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/mm/hash_utils_64.c