/*
   *  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 */