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 commit6910fa16db
, 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>
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9ffecb1028
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1a541b4e3c
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@ -79,7 +79,7 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
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#define PAGE_S2 __pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_NORMAL) | PTE_S2_RDONLY)
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#define PAGE_S2_DEVICE __pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_DEVICE_nGnRE) | PTE_S2_RDONLY | PTE_UXN)
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#define PAGE_NONE __pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE | PTE_PXN | PTE_UXN)
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#define PAGE_NONE __pgprot(((_PAGE_DEFAULT) & ~PTE_VALID) | PTE_PROT_NONE | PTE_PXN | PTE_UXN)
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#define PAGE_SHARED __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE)
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#define PAGE_SHARED_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_WRITE)
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#define PAGE_COPY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
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@ -496,7 +496,7 @@ static inline pud_t *pud_offset(pgd_t *pgd, unsigned long addr)
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static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
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{
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const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY |
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PTE_PROT_NONE | PTE_WRITE | PTE_TYPE_MASK;
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PTE_PROT_NONE | PTE_VALID | PTE_WRITE;
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/* preserve the hardware dirty information */
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if (pte_hw_dirty(pte))
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pte = pte_mkdirty(pte);
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