/*
 *  mm/pgtable-generic.c
 *
 *  Generic pgtable methods declared in asm-generic/pgtable.h
 *
 *  Copyright (C) 2010  Linus Torvalds
 */

#include <linux/pagemap.h>
#include <asm/tlb.h>
#include <asm-generic/pgtable.h>

/*
 * If a p?d_bad entry is found while walking page tables, report
 * the error, before resetting entry to p?d_none.  Usually (but
 * very seldom) called out from the p?d_none_or_clear_bad macros.
 */

void pgd_clear_bad(pgd_t *pgd)
{
        pgd_ERROR(*pgd);
        pgd_clear(pgd);
}

void pud_clear_bad(pud_t *pud)
{
        pud_ERROR(*pud);
        pud_clear(pud);
}

void pmd_clear_bad(pmd_t *pmd)
{
        pmd_ERROR(*pmd);
        pmd_clear(pmd);
}

#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
/*
 * Only sets the access flags (dirty, accessed), as well as write 
 * permission. Furthermore, we know it always gets set to a "more
 * permissive" setting, which allows most architectures to optimize
 * this. We return whether the PTE actually changed, which in turn
 * instructs the caller to do things like update__mmu_cache.  This
 * used to be done in the caller, but sparc needs minor faults to
 * force that call on sun4c so we changed this macro slightly
 */
int ptep_set_access_flags(struct vm_area_struct *vma,
                          unsigned long address, pte_t *ptep,
                          pte_t entry, int dirty)
{
        int changed = !pte_same(*ptep, entry);
        if (changed) {
                set_pte_at(vma->vm_mm, address, ptep, entry);
                flush_tlb_fix_spurious_fault(vma, address);
        }
        return changed;
}
#endif

#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
int ptep_clear_flush_young(struct vm_area_struct *vma,
                           unsigned long address, pte_t *ptep)
{
        int young;
        young = ptep_test_and_clear_young(vma, address, ptep);
        if (young)
                flush_tlb_page(vma, address);
        return young;
}
#endif

#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
                       pte_t *ptep)
{
        struct mm_struct *mm = (vma)->vm_mm;
        pte_t pte;
        pte = ptep_get_and_clear(mm, address, ptep);
        if (pte_accessible(mm, pte))
                flush_tlb_page(vma, address);
        return pte;
}
#endif

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
int pmdp_set_access_flags(struct vm_area_struct *vma,
                          unsigned long address, pmd_t *pmdp,
                          pmd_t entry, int dirty)
{
        int changed = !pmd_same(*pmdp, entry);
        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
        if (changed) {
                set_pmd_at(vma->vm_mm, address, pmdp, entry);
                flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
        }
        return changed;
}
#endif

#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
int pmdp_clear_flush_young(struct vm_area_struct *vma,
                           unsigned long address, pmd_t *pmdp)
{
        int young;
        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
        young = pmdp_test_and_clear_young(vma, address, pmdp);
        if (young)
                flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
        return young;
}
#endif

#ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
                            pmd_t *pmdp)
{
        pmd_t pmd;
        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
        VM_BUG_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
        pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
        flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
        return pmd;
}
#endif

#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
                                pgtable_t pgtable)
{
        assert_spin_locked(pmd_lockptr(mm, pmdp));

        /* FIFO */
        if (!pmd_huge_pte(mm, pmdp))
                INIT_LIST_HEAD(&pgtable->lru);
        else
                list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru);
        pmd_huge_pte(mm, pmdp) = pgtable;
}
#endif

#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
/* no "address" argument so destroys page coloring of some arch */
pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
        pgtable_t pgtable;

        assert_spin_locked(pmd_lockptr(mm, pmdp));

        /* FIFO */
        pgtable = pmd_huge_pte(mm, pmdp);
        pmd_huge_pte(mm, pmdp) = list_first_entry_or_null(&pgtable->lru,
                                                          struct page, lru);
        if (pmd_huge_pte(mm, pmdp))
                list_del(&pgtable->lru);
        return pgtable;
}
#endif

#ifndef __HAVE_ARCH_PMDP_INVALIDATE
void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
                     pmd_t *pmdp)
{
        pmd_t entry = *pmdp;
        set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(entry));
        flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
}
#endif

#ifndef pmdp_collapse_flush
pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
                          pmd_t *pmdp)
{
        /*
         * pmd and hugepage pte format are same. So we could
         * use the same function.
         */
        pmd_t pmd;

        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
        VM_BUG_ON(pmd_trans_huge(*pmdp));
        pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);

        /* collapse entails shooting down ptes not pmd */
        flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
        return pmd;
}
#endif
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */