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    Subjectpage fault scalability patch V9: [5/7] atomic pte operations for i386
    Changelog
    * Atomic pte operations for i386
    * Needs the general cmpxchg patch for i386

    Signed-off-by: Christoph Lameter <clameter@sgi.com>

    Index: linus/include/asm-i386/pgtable.h
    ===================================================================
    --- linus.orig/include/asm-i386/pgtable.h 2004-09-18 14:25:23.000000000 -0700
    +++ linus/include/asm-i386/pgtable.h 2004-09-18 15:41:52.000000000 -0700
    @@ -412,6 +412,7 @@
    #define __HAVE_ARCH_PTEP_SET_WRPROTECT
    #define __HAVE_ARCH_PTEP_MKDIRTY
    #define __HAVE_ARCH_PTE_SAME
    +#define __HAVE_ARCH_ATOMIC_TABLE_OPS
    #include <asm-generic/pgtable.h>

    #endif /* _I386_PGTABLE_H */
    Index: linus/include/asm-i386/pgtable-3level.h
    ===================================================================
    --- linus.orig/include/asm-i386/pgtable-3level.h 2004-09-18 14:25:23.000000000 -0700
    +++ linus/include/asm-i386/pgtable-3level.h 2004-09-18 15:41:52.000000000 -0700
    @@ -6,7 +6,8 @@
    * tables on PPro+ CPUs.
    *
    * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
    - */
    + * August 26, 2004 added ptep_cmpxchg and ptep_xchg <christoph@lameter.com>
    +*/

    #define pte_ERROR(e) \
    printk("%s:%d: bad pte %p(%08lx%08lx).\n", __FILE__, __LINE__, &(e), (e).pte_high, (e).pte_low)
    @@ -141,4 +142,26 @@
    #define __pte_to_swp_entry(pte) ((swp_entry_t){ (pte).pte_high })
    #define __swp_entry_to_pte(x) ((pte_t){ 0, (x).val })

    +/* Atomic PTE operations */
    +static inline pte_t ptep_xchg(struct mm_struct *mm, pte_t *ptep, pte_t newval)
    +{
    + pte_t res;
    +
    + /* xchg acts as a barrier before the setting of the high bits.
    + * (But we also have a cmpxchg8b. Why not use that? (cl))
    + */
    + res.pte_low = xchg(&ptep->pte_low, newval.pte_low);
    + res.pte_high = ptep->pte_high;
    + ptep->pte_high = newval.pte_high;
    +
    + return res;
    +}
    +
    +
    +static inline int ptep_cmpxchg(struct mm_struct *mm, unsigned long address, pte_t *ptep, pte_t oldval, pte_t newval)
    +{
    + return cmpxchg(ptep, pte_val(oldval), pte_val(newval)) == pte_val(oldval);
    +}
    +
    +
    #endif /* _I386_PGTABLE_3LEVEL_H */
    Index: linus/include/asm-i386/pgtable-2level.h
    ===================================================================
    --- linus.orig/include/asm-i386/pgtable-2level.h 2004-09-18 14:25:23.000000000 -0700
    +++ linus/include/asm-i386/pgtable-2level.h 2004-09-18 15:41:52.000000000 -0700
    @@ -82,4 +82,8 @@
    #define __pte_to_swp_entry(pte) ((swp_entry_t) { (pte).pte_low })
    #define __swp_entry_to_pte(x) ((pte_t) { (x).val })

    +/* Atomic PTE operations */
    +#define ptep_xchg(mm,xp,a) __pte(xchg(&(xp)->pte_low, (a).pte_low))
    +#define ptep_cmpxchg(mm,a,xp,oldpte,newpte) (cmpxchg(&(xp)->pte_low, (oldpte).pte_low, (newpte).pte_low)==(oldpte).pte_low)
    +
    #endif /* _I386_PGTABLE_2LEVEL_H */
    Index: linus/include/asm-i386/pgalloc.h
    ===================================================================
    --- linus.orig/include/asm-i386/pgalloc.h 2004-09-18 14:25:23.000000000 -0700
    +++ linus/include/asm-i386/pgalloc.h 2004-09-18 15:41:52.000000000 -0700
    @@ -7,6 +7,8 @@
    #include <linux/threads.h>
    #include <linux/mm.h> /* for struct page */

    +#define PMD_NONE 0L
    +
    #define pmd_populate_kernel(mm, pmd, pte) \
    set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte)))

    @@ -16,6 +18,19 @@
    ((unsigned long long)page_to_pfn(pte) <<
    (unsigned long long) PAGE_SHIFT)));
    }
    +
    +/* Atomic version */
    +static inline int pmd_test_and_populate(struct mm_struct *mm, pmd_t *pmd, struct page *pte)
    +{
    +#ifdef CONFIG_X86_PAE
    + return cmpxchg8b( ((unsigned long long *)pmd), PMD_NONE, _PAGE_TABLE +
    + ((unsigned long long)page_to_pfn(pte) <<
    + (unsigned long long) PAGE_SHIFT) ) == PMD_NONE;
    +#else
    + return cmpxchg( (unsigned long *)pmd, PMD_NONE, _PAGE_TABLE + (page_to_pfn(pte) << PAGE_SHIFT)) == PMD_NONE;
    +#endif
    +}
    +
    /*
    * Allocate and free page tables.
    */
    @@ -49,6 +64,7 @@
    #define pmd_free(x) do { } while (0)
    #define __pmd_free_tlb(tlb,x) do { } while (0)
    #define pgd_populate(mm, pmd, pte) BUG()
    +#define pgd_test_and_populate(mm, pmd, pte) ({ BUG(); 1; })

    #define check_pgt_cache() do { } while (0)

    -
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