ARM64: mm: Move PTE_PROT_NONE bit.
Under ARM64, PTEs can be broadly categorised as follows: - Present and valid: Bit #0 is set. The PTE is valid and memory access to the region may fault. - Present and invalid: Bit #0 is clear and bit #1 is set. Represents present memory with PROT_NONE protection. The PTE is an invalid entry, and the user fault handler will raise a SIGSEGV. - Not present (file or swap): Bits #0 and #1 are clear. Memory represented has been paged out. The PTE is an invalid entry, and the fault handler will try and re-populate the memory where necessary. Huge PTEs are block descriptors that have bit #1 clear. If we wish to represent PROT_NONE huge PTEs we then run into a problem as there is no way to distinguish between regular and huge PTEs if we set bit #1. To resolve this ambiguity this patch moves PTE_PROT_NONE from bit #1 to bit #2 and moves PTE_FILE from bit #2 to bit #3. The number of swap/file bits is reduced by 1 as a consequence, leaving 60 bits for file and swap entries. Signed-off-by: Steve Capper <steve.capper@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
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@ -25,8 +25,8 @@
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* Software defined PTE bits definition.
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* Software defined PTE bits definition.
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*/
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*/
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#define PTE_VALID (_AT(pteval_t, 1) << 0)
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#define PTE_VALID (_AT(pteval_t, 1) << 0)
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#define PTE_PROT_NONE (_AT(pteval_t, 1) << 1) /* only when !PTE_VALID */
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#define PTE_PROT_NONE (_AT(pteval_t, 1) << 2) /* only when !PTE_VALID */
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#define PTE_FILE (_AT(pteval_t, 1) << 2) /* only when !pte_present() */
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#define PTE_FILE (_AT(pteval_t, 1) << 3) /* only when !pte_present() */
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#define PTE_DIRTY (_AT(pteval_t, 1) << 55)
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#define PTE_DIRTY (_AT(pteval_t, 1) << 55)
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#define PTE_SPECIAL (_AT(pteval_t, 1) << 56)
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#define PTE_SPECIAL (_AT(pteval_t, 1) << 56)
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@ -281,12 +281,12 @@ extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
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/*
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/*
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* Encode and decode a swap entry:
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* Encode and decode a swap entry:
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* bits 0-1: present (must be zero)
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* bits 0, 2: present (must both be zero)
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* bit 2: PTE_FILE
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* bit 3: PTE_FILE
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* bits 3-8: swap type
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* bits 4-8: swap type
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* bits 9-63: swap offset
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* bits 9-63: swap offset
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*/
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*/
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#define __SWP_TYPE_SHIFT 3
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#define __SWP_TYPE_SHIFT 4
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#define __SWP_TYPE_BITS 6
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#define __SWP_TYPE_BITS 6
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#define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1)
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#define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1)
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#define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT)
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#define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT)
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@ -306,15 +306,15 @@ extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
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/*
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/*
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* Encode and decode a file entry:
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* Encode and decode a file entry:
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* bits 0-1: present (must be zero)
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* bits 0, 2: present (must both be zero)
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* bit 2: PTE_FILE
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* bit 3: PTE_FILE
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* bits 3-63: file offset / PAGE_SIZE
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* bits 4-63: file offset / PAGE_SIZE
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*/
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*/
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#define pte_file(pte) (pte_val(pte) & PTE_FILE)
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#define pte_file(pte) (pte_val(pte) & PTE_FILE)
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#define pte_to_pgoff(x) (pte_val(x) >> 3)
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#define pte_to_pgoff(x) (pte_val(x) >> 4)
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#define pgoff_to_pte(x) __pte(((x) << 3) | PTE_FILE)
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#define pgoff_to_pte(x) __pte(((x) << 4) | PTE_FILE)
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#define PTE_FILE_MAX_BITS 61
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#define PTE_FILE_MAX_BITS 60
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extern int kern_addr_valid(unsigned long addr);
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extern int kern_addr_valid(unsigned long addr);
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