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    Subject[PATCH 10 of 11] x86: allocate and initialize unshared pmds
    Date
    From
    If SHARED_KERNEL_PMD is false, then we need to allocate and initialize
    the kernel pmd. We can easily piggy-back this onto the existing pmd
    prepopulation code.

    Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
    ---
    arch/x86/mm/pgtable_32.c | 14 +++++++++++---
    1 file changed, 11 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
    --- a/arch/x86/mm/pgtable_32.c
    +++ b/arch/x86/mm/pgtable_32.c
    @@ -269,7 +269,7 @@ static void pgd_mop_up_pmds(pgd_t *pgdp)
    {
    int i;

    - for(i = 0; i < USER_PTRS_PER_PGD; i++) {
    + for(i = 0; i < UNSHARED_PTRS_PER_PGD; i++) {
    pgd_t pgd = pgdp[i];

    if (pgd_val(pgd) != 0) {
    @@ -289,6 +289,10 @@ static void pgd_mop_up_pmds(pgd_t *pgdp)
    * processor notices the update. Since this is expensive, and
    * all 4 top-level entries are used almost immediately in a
    * new process's life, we just pre-populate them here.
    + *
    + * Also, if we're in a paravirt environment where the kernel pmd is
    + * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate
    + * and initialize the kernel pmds here.
    */
    static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd)
    {
    @@ -297,13 +301,18 @@ static int pgd_prepopulate_pmd(struct mm
    int i;

    pud = pud_offset(pgd, 0);
    - for (addr = i = 0; i < USER_PTRS_PER_PGD; i++, pud++, addr += PUD_SIZE) {
    + for (addr = i = 0; i < UNSHARED_PTRS_PER_PGD;
    + i++, pud++, addr += PUD_SIZE) {
    pmd_t *pmd = pmd_alloc_one(mm, addr);

    if (!pmd) {
    pgd_mop_up_pmds(pgd);
    return 0;
    }
    +
    + if (i >= USER_PTRS_PER_PGD)
    + memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]),
    + sizeof(pmd_t) * PTRS_PER_PMD);

    pud_populate(mm, pud, pmd);
    }
    @@ -346,4 +355,3 @@ void check_pgt_cache(void)
    {
    quicklist_trim(0, pgd_dtor, 25, 16);
    }
    -



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