static inline int copy_pte_range(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long address, unsigned long size, int cow)
{
	pte_t * src_pte, * dst_pte;
	unsigned long end;

	if (pmd_none(*src_pmd))
		return 0;
	if (pmd_bad(*src_pmd)) {
		printk("copy_pte_range: bad pmd (%08lx)\n", pmd_val(*src_pmd));
		pmd_clear(src_pmd);
		return 0;
	}
	src_pte = pte_offset(src_pmd, address);
	if (pmd_none(*dst_pmd)) {
		if (!pte_alloc(dst_pmd, 0))
			return -ENOMEM;
	}
	dst_pte = pte_offset(dst_pmd, address);
	address &= ~PMD_MASK;
	end = address + size;
	if (end >= PMD_SIZE)
		end = PMD_SIZE;
	do {
		/* I would like to switch arguments here, to make it
		 * consistent with copy_xxx_range and memcpy syntax.
		 */
		copy_one_pte(src_pte++, dst_pte++, cow);
		address += PAGE_SIZE;
	} while (address < end);
	return 0;
}

static inline void zap_pte_range(pmd_t * pmd, unsigned long address, unsigned long size)
{
	pte_t * pte;

	if (pmd_none(*pmd))
		return;
	if (pmd_bad(*pmd)) {
		printk("zap_pte_range: bad pmd (%08lx)\n", pmd_val(*pmd));
		pmd_clear(pmd);
		return;
	}
	pte = pte_offset(pmd, address);
	address &= ~PMD_MASK;
	if (address + size > PMD_SIZE)
		size = PMD_SIZE - address;
	size >>= PAGE_SHIFT;
	for (;;) {
		pte_t page;
		if (!size)
			break;
		page = *pte;
		pte++;
		size--;
		if (pte_none(page))
			continue;
		pte_clear(pte-1);
		free_pte(page);
	}
}

/*
 * This function zeroes out partial mmap'ed pages at truncation time..
 */
static void partial_clear(struct vm_area_struct *vma, unsigned long address)
{
	pgd_t *page_dir;
	pmd_t *page_middle;
	pte_t *page_table, pte;

	page_dir = pgd_offset(vma->vm_mm, address);
	if (pgd_none(*page_dir))
		return;
	if (pgd_bad(*page_dir)) {
		printk("bad page table directory entry %p:[%lx]\n", page_dir, pgd_val(*page_dir));
		pgd_clear(page_dir);
		return;
	}
	page_middle = pmd_offset(page_dir, address);
	if (pmd_none(*page_middle))
		return;
	if (pmd_bad(*page_middle)) {
		printk("bad page table directory entry %p:[%lx]\n", page_dir, pgd_val(*page_dir));
		pmd_clear(page_middle);
		return;
	}
	page_table = pte_offset(page_middle, address);
	pte = *page_table;
	if (!pte_present(pte))
		return;
	flush_cache_page(vma, address);
	address &= ~PAGE_MASK;
	address += pte_page(pte);
	if (address >= high_memory)
		return;
	memset((void *) address, 0, PAGE_SIZE - (address & ~PAGE_MASK));
	flush_page_to_ram(pte_page(pte));
}

static unsigned long get_phys_addr(struct task_struct * p, unsigned long ptr)
{
    pgd_t *page_dir;
    pmd_t *page_middle;
    pte_t pte;

    if (!p || !p->mm || ptr >= TASK_SIZE)
        return 0;
    page_dir = pgd_offset(p->mm,ptr);
    if (pgd_none(*page_dir))
        return 0;
    if (pgd_bad(*page_dir)) {
        printk("bad page directory entry %08lx\n", pgd_val(*page_dir));
        pgd_clear(page_dir);
        return 0;
    }
    page_middle = pmd_offset(page_dir,ptr);
    if (pmd_none(*page_middle))
        return 0;
    if (pmd_bad(*page_middle)) {
        printk("bad page middle entry %08lx\n", pmd_val(*page_middle));
        pmd_clear(page_middle);
        return 0;
    }
    pte = *pte_offset(page_middle,ptr);
    if (!pte_present(pte))
        return 0;
    return pte_page(pte) + (ptr & ~PAGE_MASK);
}

static inline void
remove_mapping_pte_range (pmd_t *pmd, unsigned long address, unsigned long size)
{
	pte_t *pte;
	unsigned long end;

	if (pmd_none (*pmd))
		return;
	if (pmd_bad (*pmd)){
		printk ("remove_graphics_pte_range: bad pmd (%08lx)\n", pmd_val (*pmd));
		pmd_clear (pmd);
		return;
	}
	pte = pte_offset (pmd, address);
	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		pte_t entry = *pte;
		if (pte_present (entry))
			set_pte (pte, pte_modify (entry, PAGE_NONE));
		address += PAGE_SIZE;
		pte++;
	} while (address < end);
						  
}

void free_pgd_slow(pgd_t *pgd)
{
	pmd_t *pmd;
	pte_t *pte;

	if (!pgd)
		return;

	/* pgd is always present and good */
	pmd = (pmd_t *)pgd;
	if (pmd_none(*pmd))
		goto free;
	if (pmd_bad(*pmd)) {
		pmd_ERROR(*pmd);
		pmd_clear(pmd);
		goto free;
	}

	pte = pte_offset(pmd, 0);
	pmd_clear(pmd);
	pte_free(pte);
	pmd_free(pmd);
free:
	free_pages((unsigned long) pgd, 2);
}

/* The pgtable.h claims some functions generically exist, but I
 * can't find them......
 */
pte_t *va_to_pte(unsigned long address)
{
	pgd_t *dir;
	pmd_t *pmd;
	pte_t *pte;
	struct mm_struct *mm;

	if (address < TASK_SIZE)
		mm = current->mm;
	else
		mm = &init_mm;

	dir = pgd_offset(mm, address & PAGE_MASK);
	if (dir) {
		pmd = pmd_offset(dir, address & PAGE_MASK);
		if (pmd && pmd_present(*pmd)) {
			pte = pte_offset(pmd, address & PAGE_MASK);
			if (pte && pte_present(*pte)) {
				return(pte);
			}
		}
		else {
			return (0);
		}
	}
	else {
		return (0);
	}
	return (0);
}

/* we parse the page tables in order to find the direct mapping of
   the page. This works only without holding any locks for pages we
   are sure that they do not move in memory.
*/
volatile void *virt_to_kseg(volatile void *address)
{
        pgd_t *pgd; pmd_t *pmd; pte_t *ptep, pte;
        unsigned long va, ret = 0UL;
        
        va=VMALLOC_VMADDR((unsigned long)address);
        
        /* get the page directory. Use the kernel memory map. */
        pgd = pgd_offset_k(va);

        /* check whether we found an entry */
        if (!pgd_none(*pgd))
        {
              /* get the page middle directory */
              pmd = pmd_offset(pgd, va);
              /* check whether we found an entry */
              if (!pmd_none(*pmd))
              {
                  /* get a pointer to the page table entry */
                  ptep = pte_offset(pmd, va);
                  pte = *ptep;
                  /* check for a valid page */
                  if (pte_present(pte))
                  {
                        /* get the address the page is refering to */
                        ret = (unsigned long)page_address(pte_page(pte));
                        /* add the offset within the page to the page address */
                        ret |= (va & (PAGE_SIZE -1));
                  }
              }
        }
        return((volatile void *)ret);
}

/* Places into character array, the status of all the pages in the passed
 * range from 'addr' to 'addr + len'.  -1 on failure, 0 on success...
 * The encoding in each character is:
 * low-bit is zero == Page is not in physical ram right now
 * low-bit is one  == Page is currently residing in core
 * All other bits are undefined within the character so there...
 * Also, if you try to get stats on an area outside of the user vm area
 * *or* the passed base address is not aligned on a page boundary you
 * get an error.
 */
asmlinkage int sunos_mincore(unsigned long addr, unsigned long len, char *array)
{
	pgd_t *pgdp;
	pmd_t *pmdp;
	pte_t *ptep;
	unsigned long limit;
	int num_pages, pnum;

	if(addr & (PAGE_SIZE - 1))
		return -EINVAL;

	num_pages = (len / PAGE_SIZE);
	if(verify_area(VERIFY_WRITE, array, num_pages))
		return -EFAULT; /* bum array, you lose... */
	if((addr >= KERNBASE) || ((addr + len) > KERNBASE))
		return -ENOMEM; /* I'm sure you're curious about kernel mappings.. */

	/* Wheee, go through pte's */
	pnum = 0;
	for(limit = addr + len; addr < limit; addr += PAGE_SIZE, pnum++) {
		pgdp = pgd_offset(current->mm, addr);
		if(pgd_none(*pgdp))
			return -ENOMEM; /* As per SunOS manpage */
		pmdp = pmd_offset(pgdp, addr);
		if(pmd_none(*pmdp))
			return -ENOMEM; /* As per SunOS manpage */
		ptep = pte_offset(pmdp, addr);
		if(pte_none(*ptep))
			return -ENOMEM; /* As per SunOS manpage */
		/* Page in core or Swapped page? */
		array[pnum] = pte_present(*ptep) ? 1 : 0;
	}
	return 0; /* Success... I think... */
}

static inline int unuse_pmd(struct vm_area_struct * vma, pmd_t *dir,
	unsigned long address, unsigned long size, unsigned long offset,
	unsigned int type, unsigned long page)
{
	pte_t * pte;
	unsigned long end;

	if (pmd_none(*dir))
		return 0;
	if (pmd_bad(*dir)) {
		printk("unuse_pmd: bad pmd (%08lx)\n", pmd_val(*dir));
		pmd_clear(dir);
		return 0;
	}
	pte = pte_offset(dir, address);
	offset += address & PMD_MASK;
	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		if (unuse_pte(vma, offset+address-vma->vm_start, pte, type, page))
			return 1;
		address += PAGE_SIZE;
		pte++;
	} while (address < end);
	return 0;
}

static inline void unswap_pmd(struct vm_area_struct * vma, pmd_t *dir,
			      unsigned long address, unsigned long size,
			      unsigned long offset, unsigned long entry,
			      unsigned long page /* , int isswap */)
{
	pte_t * pte;
	unsigned long end;

	if (pmd_none(*dir))
		return;
	if (pmd_bad(*dir)) {
		printk("unswap_pmd: bad pmd (%08lx)\n", pmd_val(*dir));
		pmd_clear(dir);
		return;
	}
	pte = pte_offset(dir, address);
	offset += address & PMD_MASK;
	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		unswap_pte(vma, offset+address-vma->vm_start, pte, entry,
			   page /* , isswap */);
		address += PAGE_SIZE;
		pte++;
	} while (address < end);
}

void
print_8xx_pte(struct mm_struct *mm, unsigned long addr)
{
        pgd_t * pgd;
        pmd_t * pmd;
        pte_t * pte;

        printk(" pte @ 0x%8lx: ", addr);
        pgd = pgd_offset(mm, addr & PAGE_MASK);
        if (pgd) {
                pmd = pmd_offset(pgd, addr & PAGE_MASK);
                if (pmd && pmd_present(*pmd)) {
                        pte = pte_offset(pmd, addr & PAGE_MASK);
                        if (pte) {
                                printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n",
                                        (long)pgd, (long)pte, (long)pte_val(*pte));
#define pp ((long)pte_val(*pte))				
				printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx "
				       "CI: %lx v: %lx\n",
				       pp>>12,    /* rpn */
				       (pp>>10)&3, /* pp */
				       (pp>>3)&1, /* small */
				       (pp>>2)&1, /* shared */
				       (pp>>1)&1, /* cache inhibit */
				       pp&1       /* valid */
				       );
#undef pp				
                        }
                        else {
                                printk("no pte\n");
                        }
                }

static inline int swap_out_pmd(struct mm_struct * mm, struct vm_area_struct * vma, pmd_t *dir, unsigned long address, unsigned long end, int gfp_mask)
{
	pte_t * pte;
	unsigned long pmd_end;

	if (pmd_none(*dir))
		return 0;
	if (pmd_bad(*dir)) {
		pmd_ERROR(*dir);
		pmd_clear(dir);
		return 0;
	}
	
	pte = pte_offset(dir, address);
	
	pmd_end = (address + PMD_SIZE) & PMD_MASK;
	if (end > pmd_end)
		end = pmd_end;

	do {
		int result;
		mm->swap_address = address + PAGE_SIZE;
		result = try_to_swap_out(mm, vma, address, pte, gfp_mask);
		if (result)
			return result;
		if (!mm->swap_cnt)
			return 0;
		address += PAGE_SIZE;
		pte++;
	} while (address && (address < end));
	return 0;
}

static inline void iterate_pte(pmd_t * pmd, unsigned long address,
                               unsigned long size, pte_iterator_t op,
                               unsigned long arg)
{
    pte_t *pte;
    unsigned long end;

    if (pmd_none(*pmd))
        return;
    if (pmd_bad(*pmd)) {
        pmd_ERROR(*pmd);
        pmd_clear(pmd);
        return;
    }
    pte = pte_offset(pmd, address);
    address &= ~PMD_MASK;
    end = address + size;
    if (end > PMD_SIZE)
        end = PMD_SIZE;
    do {
        op(pte, arg);
        address += PAGE_SIZE;
        pte++;
    } while (address < end);
}

/*
 * maps a range of vmalloc()ed memory into the requested pages. the old
 * mappings are removed. 
 */
static inline void
vmap_pte_range (pte_t *pte, unsigned long address, unsigned long size, unsigned long vaddr)
{
	unsigned long end;
	pgd_t *vdir;
	pmd_t *vpmd;
	pte_t *vpte;
	
	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		pte_t oldpage = *pte;
		struct page * page;
		pte_clear(pte);

		vdir = pgd_offset_k (vaddr);
		vpmd = pmd_offset (vdir, vaddr);
		vpte = pte_offset (vpmd, vaddr);
		page = pte_page (*vpte);

		set_pte(pte, mk_pte(page, PAGE_USERIO));
		forget_pte(oldpage);
		address += PAGE_SIZE;
		vaddr += PAGE_SIZE;
		pte++;
	} while (address < end);
}

static inline int zap_pte_range(struct mm_struct *mm, pmd_t * pmd, unsigned long address, unsigned long size)
{
	pte_t * pte;
	int freed;

	if (pmd_none(*pmd))
		return 0;
	if (pmd_bad(*pmd)) {
		pmd_ERROR(*pmd);
		pmd_clear(pmd);
		return 0;
	}
	pte = pte_offset(pmd, address);
	address &= ~PMD_MASK;
	if (address + size > PMD_SIZE)
		size = PMD_SIZE - address;
	size >>= PAGE_SHIFT;
	freed = 0;
	for (;;) {
		pte_t page;
		if (!size)
			break;
		page = ptep_get_and_clear(pte);
		pte++;
		size--;
		if (pte_none(page))
			continue;
		freed += free_pte(page);
	}
	return freed;
}

pgd_t *get_pgd_slow(struct mm_struct *mm)
{
	pgd_t *new_pgd, *init_pgd;
	pmd_t *new_pmd, *init_pmd;
	pte_t *new_pte, *init_pte;

	new_pgd = alloc_pgd_table(GFP_KERNEL);
	if (!new_pgd)
		goto no_pgd;

	/*
	 * This lock is here just to satisfy pmd_alloc and pte_lock
	 */
	spin_lock(&mm->page_table_lock);

	/*
	 * On ARM, first page must always be allocated since it contains
	 * the machine vectors.
	 */
	new_pmd = pmd_alloc(mm, new_pgd, 0);
	if (!new_pmd)
		goto no_pmd;

	new_pte = pte_alloc(mm, new_pmd, 0);
	if (!new_pte)
		goto no_pte;

	init_pgd = pgd_offset_k(0);
	init_pmd = pmd_offset(init_pgd, 0);
	init_pte = pte_offset(init_pmd, 0);

	set_pte(new_pte, *init_pte);

	/*
	 * most of the page table entries are zeroed
	 * wne the table is created.
	 */
	memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
		(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));

	spin_unlock(&mm->page_table_lock);

	/* update MEMC tables */
	cpu_memc_update_all(new_pgd);
	return new_pgd;

no_pte:
	spin_unlock(&mm->page_table_lock);
	pmd_free(new_pmd);
	free_pgd_slow(new_pgd);
	return NULL;

no_pmd:
	spin_unlock(&mm->page_table_lock);
	free_pgd_slow(new_pgd);
	return NULL;

no_pgd:
	return NULL;
}

static struct page *lookup_page_table(const struct mm_struct *mm,unsigned int address,int clear) {
    pgd_t *pgd;
    pmd_t *pmd;
    pte_t *pte;
    struct page *page = NOPAGE_SIGBUS;//default no PAGE
    pgd = pgd_offset(mm,address);
    if(! pgd_none(*pgd) ) {
        /*Go  for a PMD lookup */
        pmd = pmd_offset(pgd,address);
        if( ! pmd_none(*pmd) ) {
            pte = pte_offset(pmd,address); //get the Pte entry 
            if(pte_present(*pte) ) {
                page = pte_page(*pte); //get the page from the entry
                if(clear && VALID_PAGE(page) && (!PageReserved(page) ) ) {
                    pte_t x = ptep_get_and_clear(pte); //clear the pte
                    (void)x;
#ifdef DEBUG_NOT_NOW
                    printk(KERN_ALERT "Non Contiguous Pages getting cleared off the List(%lx):\n",PAGE_VIRTUAL(page)); 
#endif
                    __free_page(page); //free of the page
                    page = (struct page *) 1;
                }
            }
        }
    }
    return page;
}

/**
 * kvm_mips_walk_pgd() - Walk page table with optional allocation.
 * @pgd:	Page directory pointer.
 * @addr:	Address to index page table using.
 * @cache:	MMU page cache to allocate new page tables from, or NULL.
 *
 * Walk the page tables pointed to by @pgd to find the PTE corresponding to the
 * address @addr. If page tables don't exist for @addr, they will be created
 * from the MMU cache if @cache is not NULL.
 *
 * Returns:	Pointer to pte_t corresponding to @addr.
 *		NULL if a page table doesn't exist for @addr and [email protected]
 *		NULL if a page table allocation failed.
 */
static pte_t *kvm_mips_walk_pgd(pgd_t *pgd, struct kvm_mmu_memory_cache *cache,
				unsigned long addr)
{
	pud_t *pud;
	pmd_t *pmd;

	pgd += pgd_index(addr);
	if (pgd_none(*pgd)) {
		/* Not used on MIPS yet */
		BUG();
		return NULL;
	}
	pud = pud_offset(pgd, addr);
	if (pud_none(*pud)) {
		pmd_t *new_pmd;

		if (!cache)
			return NULL;
		new_pmd = mmu_memory_cache_alloc(cache);
		pmd_init((unsigned long)new_pmd,
			 (unsigned long)invalid_pte_table);
		pud_populate(NULL, pud, new_pmd);
	}
	pmd = pmd_offset(pud, addr);
	if (pmd_none(*pmd)) {
		pte_t *new_pte;

		if (!cache)
			return NULL;
		new_pte = mmu_memory_cache_alloc(cache);
		clear_page(new_pte);
		pmd_populate_kernel(NULL, pmd, new_pte);
	}
	return pte_offset(pmd, addr);
}

static bool kvm_mips_flush_gpa_pmd(pmd_t *pmd, unsigned long start_gpa,
				   unsigned long end_gpa)
{
	pte_t *pte;
	unsigned long end = ~0ul;
	int i_min = __pmd_offset(start_gpa);
	int i_max = __pmd_offset(end_gpa);
	bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);
	int i;

	for (i = i_min; i <= i_max; ++i, start_gpa = 0) {
		if (!pmd_present(pmd[i]))
			continue;

		pte = pte_offset(pmd + i, 0);
		if (i == i_max)
			end = end_gpa;

		if (kvm_mips_flush_gpa_pte(pte, start_gpa, end)) {
			pmd_clear(pmd + i);
			pte_free_kernel(NULL, pte);
		} else {
			safe_to_remove = false;
		}
	}
	return safe_to_remove;
}