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    Subject[RFC PATCH 04/18] ARM: LPAE: Do not assume Linux PTEs are always at PTRS_PER_PTE offset
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    Placing the Linux PTEs at a 2KB offset inside a page is a workaround for
    the 2-level page table format where not enough spare bits are available.
    With LPAE this is no longer required. This patch changes such assumption
    by using a different macro, LINUX_PTE_OFFSET, which is defined to
    PTRS_PER_PTE for the 2-level page tables.

    Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
    ---
    arch/arm/include/asm/pgalloc.h | 6 +++---
    arch/arm/include/asm/pgtable-2level.h | 1 +
    arch/arm/include/asm/pgtable.h | 6 +++---
    arch/arm/mm/fault.c | 2 +-
    arch/arm/mm/mmu.c | 3 ++-
    5 files changed, 10 insertions(+), 8 deletions(-)

    diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h
    index b12cc98..c2a1f64 100644
    --- a/arch/arm/include/asm/pgalloc.h
    +++ b/arch/arm/include/asm/pgalloc.h
    @@ -62,7 +62,7 @@ pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
    pte = (pte_t *)__get_free_page(PGALLOC_GFP);
    if (pte) {
    clean_dcache_area(pte, sizeof(pte_t) * PTRS_PER_PTE);
    - pte += PTRS_PER_PTE;
    + pte += LINUX_PTE_OFFSET;
    }

    return pte;
    @@ -95,7 +95,7 @@ pte_alloc_one(struct mm_struct *mm, unsigned long addr)
    static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
    {
    if (pte) {
    - pte -= PTRS_PER_PTE;
    + pte -= LINUX_PTE_OFFSET;
    free_page((unsigned long)pte);
    }
    }
    @@ -128,7 +128,7 @@ pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp, pte_t *ptep)
    * The pmd must be loaded with the physical
    * address of the PTE table
    */
    - pte_ptr -= PTRS_PER_PTE * sizeof(void *);
    + pte_ptr -= LINUX_PTE_OFFSET * sizeof(void *);
    __pmd_populate(pmdp, __pa(pte_ptr) | _PAGE_KERNEL_TABLE);
    }

    diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
    index d60bda9..36bdef7 100644
    --- a/arch/arm/include/asm/pgtable-2level.h
    +++ b/arch/arm/include/asm/pgtable-2level.h
    @@ -71,6 +71,7 @@
    #define PTRS_PER_PTE 512
    #define PTRS_PER_PMD 1
    #define PTRS_PER_PGD 2048
    +#define LINUX_PTE_OFFSET PTRS_PER_PTE

    /*
    * PMD_SHIFT determines the size of the area a second-level page table can map
    diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
    index 49dd19e..5b45463 100644
    --- a/arch/arm/include/asm/pgtable.h
    +++ b/arch/arm/include/asm/pgtable.h
    @@ -137,8 +137,8 @@ extern struct page *empty_zero_page;
    #define __pte_map(dir,km) pmd_page_vaddr(*(dir))
    #define __pte_unmap(pte,km) do { } while (0)
    #else
    -#define __pte_map(dir,km) ((pte_t *)kmap_atomic(pmd_page(*(dir)), km) + PTRS_PER_PTE)
    -#define __pte_unmap(pte,km) kunmap_atomic((pte - PTRS_PER_PTE), km)
    +#define __pte_map(dir,km) ((pte_t *)kmap_atomic(pmd_page(*(dir)), km) + LINUX_PTE_OFFSET)
    +#define __pte_unmap(pte,km) kunmap_atomic((pte - LINUX_PTE_OFFSET), km)
    #endif

    #define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext)
    @@ -234,7 +234,7 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
    unsigned long ptr;

    ptr = pmd_val(pmd) & ~(PTRS_PER_PTE * sizeof(void *) - 1);
    - ptr += PTRS_PER_PTE * sizeof(void *);
    + ptr += LINUX_PTE_OFFSET * sizeof(void *);

    return __va(ptr);
    }
    diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
    index 23b0b03..2966897 100644
    --- a/arch/arm/mm/fault.c
    +++ b/arch/arm/mm/fault.c
    @@ -108,7 +108,7 @@ void show_pte(struct mm_struct *mm, unsigned long addr)

    pte = pte_offset_map(pmd, addr);
    printk(", *pte=%08lx", pte_val(*pte));
    - printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
    + printk(", *ppte=%08lx", pte_val(pte[-LINUX_PTE_OFFSET]));
    pte_unmap(pte);
    } while(0);

    diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
    index 56df812..3d6b206 100644
    --- a/arch/arm/mm/mmu.c
    +++ b/arch/arm/mm/mmu.c
    @@ -538,7 +538,8 @@ static void __init *early_alloc(unsigned long sz)
    static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr, unsigned long prot)
    {
    if (pmd_none(*pmd)) {
    - pte_t *pte = early_alloc(2 * PTRS_PER_PTE * sizeof(pte_t));
    + pte_t *pte = early_alloc((LINUX_PTE_OFFSET +
    + PTRS_PER_PTE) * sizeof(pte_t));
    __pmd_populate(pmd, __pa(pte) | prot);
    }
    BUG_ON(pmd_bad(*pmd));


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