Steve Capper 1a541b4e3c arm64: Fix THP protection change logic ... 6910fa1 ("arm64: enable PTE type bit in the mask for pte_modify") fixes a problem whereby a large block of PROT_NONE mapped memory is incorrectly mapped as block descriptors when mprotect is called. Unfortunately, a subtle bug was introduced by this fix to the THP logic. If one mmaps a large block of memory, then faults it such that it is collapsed into THPs; resulting calls to mprotect on this area of memory will lead to incorrect table descriptors being written instead of block descriptors. This is because pmd_modify calls pte_modify which is now allowed to modify the type of the page table entry. This patch reverts commit 6910fa16db, and fixes the problem it was trying to address by adjusting PAGE_NONE to represent a table entry. Thus no change in pte type is required when moving from PROT_NONE to a different protection. Fixes: 6910fa16db ("arm64: enable PTE type bit in the mask for pte_modify") Cc: <stable@vger.kernel.org> # 4.0+ Cc: Feng Kan <fkan@apm.com> Reported-by: Ganapatrao Kulkarni <Ganapatrao.Kulkarni@caviumnetworks.com> Tested-by: Ganapatrao Kulkarni <gkulkarni@caviumnetworks.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Steve Capper <steve.capper@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>		2015-10-01 18:02:21 +01:00
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asm	arm64: Fix THP protection change logic	2015-10-01 18:02:21 +01:00
uapi/asm	ARM:	2015-09-10 16:42:49 -07:00