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| author | Steve Capper <steve.capper@linaro.org> | 2013-05-28 13:35:51 +0100 |
|---|---|---|
| committer | Steve Capper <steve.capper@linaro.org> | 2013-06-14 09:52:19 +0100 |
| commit | 59911ca4325dc7bd95e05c988fef3593b694e62c (patch) | |
| tree | cc4a255ac8b12f57f946900f6c52e850691b2433 /arch | |
| parent | 072b1b62a6436b71ab951faae4500db2fbed63de (diff) | |
| download | linux-59911ca4325dc7bd95e05c988fef3593b694e62c.tar.gz linux-59911ca4325dc7bd95e05c988fef3593b694e62c.tar.bz2 linux-59911ca4325dc7bd95e05c988fef3593b694e62c.zip | |
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/pgtable.h | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 77b09d6fee23..2291de0258ed 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -25,8 +25,8 @@ * Software defined PTE bits definition. */ #define PTE_VALID (_AT(pteval_t, 1) << 0) -#define PTE_PROT_NONE (_AT(pteval_t, 1) << 1) /* only when !PTE_VALID */ -#define PTE_FILE (_AT(pteval_t, 1) << 2) /* only when !pte_present() */ +#define PTE_PROT_NONE (_AT(pteval_t, 1) << 2) /* only when !PTE_VALID */ +#define PTE_FILE (_AT(pteval_t, 1) << 3) /* only when !pte_present() */ #define PTE_DIRTY (_AT(pteval_t, 1) << 55) #define PTE_SPECIAL (_AT(pteval_t, 1) << 56) @@ -281,12 +281,12 @@ extern pgd_t idmap_pg_dir[PTRS_PER_PGD]; /* * Encode and decode a swap entry: - * bits 0-1: present (must be zero) - * bit 2: PTE_FILE - * bits 3-8: swap type + * bits 0, 2: present (must both be zero) + * bit 3: PTE_FILE + * bits 4-8: swap type * bits 9-63: swap offset */ -#define __SWP_TYPE_SHIFT 3 +#define __SWP_TYPE_SHIFT 4 #define __SWP_TYPE_BITS 6 #define __SWP_TYPE_MASK ((1 << __SWP_TYPE_BITS) - 1) #define __SWP_OFFSET_SHIFT (__SWP_TYPE_BITS + __SWP_TYPE_SHIFT) @@ -306,15 +306,15 @@ extern pgd_t idmap_pg_dir[PTRS_PER_PGD]; /* * Encode and decode a file entry: - * bits 0-1: present (must be zero) - * bit 2: PTE_FILE - * bits 3-63: file offset / PAGE_SIZE + * bits 0, 2: present (must both be zero) + * bit 3: PTE_FILE + * bits 4-63: file offset / PAGE_SIZE */ #define pte_file(pte) (pte_val(pte) & PTE_FILE) -#define pte_to_pgoff(x) (pte_val(x) >> 3) -#define pgoff_to_pte(x) __pte(((x) << 3) | PTE_FILE) +#define pte_to_pgoff(x) (pte_val(x) >> 4) +#define pgoff_to_pte(x) __pte(((x) << 4) | PTE_FILE) -#define PTE_FILE_MAX_BITS 61 +#define PTE_FILE_MAX_BITS 60 extern int kern_addr_valid(unsigned long addr); |