/*
 * XXX needed for backend support
 *
 */
static int
map_pte_fn(pte_t *pte, struct page *pmd_page,
           unsigned long addr, void *data)
{
    unsigned long **frames = (unsigned long **)data;

    set_pte_at(&init_mm, addr, pte, pfn_pte_ma((*frames)[0], PAGE_KERNEL));
    (*frames)++;
    return 0;
}

/*
 * 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;
}

/*
 * set a new huge pmd. We should not be called for updating
 * an existing pmd entry. That should go via pmd_hugepage_update.
 */
void set_pmd_at(struct mm_struct *mm, unsigned long addr,
		pmd_t *pmdp, pmd_t pmd)
{
#ifdef CONFIG_DEBUG_VM
	WARN_ON(pte_present(pmd_pte(*pmdp)) && !pte_protnone(pmd_pte(*pmdp)));
	assert_spin_locked(&mm->page_table_lock);
	WARN_ON(!pmd_trans_huge(pmd));
#endif
	trace_hugepage_set_pmd(addr, pmd_val(pmd));
	return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
}

pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
{
	pte_t *pte = pte_offset_kernel(pmd, addr);
	if (pte_none(*pte)) {
		pte_t entry;
		void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
		if (!p)
			return NULL;
		entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
		set_pte_at(&init_mm, addr, pte, entry);
	}

void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
		     pte_t *ptep, pte_t entry)
{
	int i;

	for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
		set_pte_at(mm, addr, ptep, entry);
		ptep++;
		addr += PAGE_SIZE;
		pte_val(entry) += PAGE_SIZE;
	}
}

/*
 * The __w1data area holds data that is only written during initialization,
 * and is read-only and thus freely cacheable thereafter.  Fix the page
 * table entries that cover that region accordingly.
 */
static void mark_w1data_ro(void)
{
	/* Loop over page table entries */
	unsigned long addr = (unsigned long)__w1data_begin;
	BUG_ON((addr & (PAGE_SIZE-1)) != 0);
	for (; addr <= (unsigned long)__w1data_end - 1; addr += PAGE_SIZE) {
		unsigned long pfn = kaddr_to_pfn((void *)addr);
		pte_t *ptep = virt_to_pte(NULL, addr);
		BUG_ON(pte_huge(*ptep));   /* not relevant for kdata_huge */
		set_pte_at(&init_mm, addr, ptep, pfn_pte(pfn, PAGE_KERNEL_RO));
	}
}

/* Remap IO memory, the same way as remap_pfn_range(), but use
 * the obio memory space.
 *
 * They use a pgprot that sets PAGE_IO and does not check the
 * mem_map table as this is independent of normal memory.
 */
static inline void io_remap_pte_range(struct mm_struct *mm, pte_t * pte,
				      unsigned long address,
				      unsigned long size,
				      unsigned long offset, pgprot_t prot,
				      int space)
{
	unsigned long end;

	/* clear hack bit that was used as a write_combine side-effect flag */
	offset &= ~0x1UL;
	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		pte_t entry;
		unsigned long curend = address + PAGE_SIZE;
		
		entry = mk_pte_io(offset, prot, space);
		if (!(address & 0xffff)) {
			if (!(address & 0x3fffff) && !(offset & 0x3ffffe) && end >= address + 0x400000) {
				entry = mk_pte_io(offset,
						  __pgprot(pgprot_val (prot) | _PAGE_SZ4MB),
						  space);
				curend = address + 0x400000;
				offset += 0x400000;
			} else if (!(address & 0x7ffff) && !(offset & 0x7fffe) && end >= address + 0x80000) {
				entry = mk_pte_io(offset,
						  __pgprot(pgprot_val (prot) | _PAGE_SZ512K),
						  space);
				curend = address + 0x80000;
				offset += 0x80000;
			} else if (!(offset & 0xfffe) && end >= address + 0x10000) {
				entry = mk_pte_io(offset,
						  __pgprot(pgprot_val (prot) | _PAGE_SZ64K),
						  space);
				curend = address + 0x10000;
				offset += 0x10000;
			} else
				offset += PAGE_SIZE;
		} else
			offset += PAGE_SIZE;

		do {
			BUG_ON(!pte_none(*pte));
			set_pte_at(mm, address, pte, entry);
			address += PAGE_SIZE;
			pte_val(entry) += PAGE_SIZE;
			pte++;
		} while (address < curend);
	} while (address < end);
}

void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
{
	unsigned long addr;
	unsigned long i;

	addr = (unsigned long)shared;

	for (i = 0; i < nr_gframes; i++) {
		set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
			   __pte(0));
		addr += PAGE_SIZE;
	}
}

static void free_init_pages(char *what, unsigned long begin, unsigned long end)
{
#ifdef CONFIG_HOMECACHE
    int home = initial_heap_home();
#endif
    unsigned long addr = (unsigned long) begin;

    if (kdata_huge && !initfree) {
        pr_warning("Warning: ignoring initfree=0:"
                   " incompatible with kdata=huge\n");
        initfree = 1;
    }
    end = (end + PAGE_SIZE - 1) & PAGE_MASK;
    local_flush_tlb_pages(NULL, begin, PAGE_SIZE, end - begin);
    for (addr = begin; addr < end; addr += PAGE_SIZE) {
        /*
         * Note we just reset the home here directly in the
         * page table.  We know this is safe because our caller
         * just flushed the caches on all the other cpus,
         * and they won't be touching any of these pages.
         */
        int pfn = kaddr_to_pfn((void *)addr);
        struct page *page = pfn_to_page(pfn);
        pte_t *ptep = virt_to_pte(NULL, addr);
        if (!initfree) {
            /*
             * If debugging page accesses then do not free
             * this memory but mark them not present - any
             * buggy init-section access will create a
             * kernel page fault:
             */
            pte_clear(&init_mm, addr, ptep);
            continue;
        }
#ifdef CONFIG_HOMECACHE
        set_page_home(page, home);
        __clear_bit(PG_homecache_nomigrate, &page->flags);
#endif
        __ClearPageReserved(page);
        init_page_count(page);
        if (pte_huge(*ptep))
            BUG_ON(!kdata_huge);
        else
            set_pte_at(&init_mm, addr, ptep,
                       pfn_pte(pfn, PAGE_KERNEL));
        memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
        free_page(addr);
        totalram_pages++;
    }
    pr_info("Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
}

/*
 * nid, region_start, and region_end are hints to try to place the page
 * table memory in the same node or region.
 */
static int __map_kernel_page(unsigned long ea, unsigned long pa,
			  pgprot_t flags,
			  unsigned int map_page_size,
			  int nid,
			  unsigned long region_start, unsigned long region_end)
{
	unsigned long pfn = pa >> PAGE_SHIFT;
	pgd_t *pgdp;
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep;
	/*
	 * Make sure task size is correct as per the max adddr
	 */
	BUILD_BUG_ON(TASK_SIZE_USER64 > RADIX_PGTABLE_RANGE);

	if (unlikely(!slab_is_available()))
		return early_map_kernel_page(ea, pa, flags, map_page_size,
						nid, region_start, region_end);

	/*
	 * Should make page table allocation functions be able to take a
	 * node, so we can place kernel page tables on the right nodes after
	 * boot.
	 */
	pgdp = pgd_offset_k(ea);
	pudp = pud_alloc(&init_mm, pgdp, ea);
	if (!pudp)
		return -ENOMEM;
	if (map_page_size == PUD_SIZE) {
		ptep = (pte_t *)pudp;
		goto set_the_pte;
	}
	pmdp = pmd_alloc(&init_mm, pudp, ea);
	if (!pmdp)
		return -ENOMEM;
	if (map_page_size == PMD_SIZE) {
		ptep = pmdp_ptep(pmdp);
		goto set_the_pte;
	}
	ptep = pte_alloc_kernel(pmdp, ea);
	if (!ptep)
		return -ENOMEM;

set_the_pte:
	set_pte_at(&init_mm, ea, ptep, pfn_pte(pfn, flags));
	smp_wmb();
	return 0;
}

static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
				unsigned long end)
{
	pte_t *pte = pte_offset_kernel(pmd, addr);
	pte_t zero_pte;

	zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);
	zero_pte = pte_wrprotect(zero_pte);

	while (addr + PAGE_SIZE <= end) {
		set_pte_at(&init_mm, addr, pte, zero_pte);
		addr += PAGE_SIZE;
		pte = pte_offset_kernel(pmd, addr);
	}
}

void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
		     pte_t *ptep, pte_t entry)
{
	int i;

	if (!pte_present(*ptep) && pte_present(entry))
		mm->context.huge_pte_count++;

	for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
		set_pte_at(mm, addr, ptep, entry);
		ptep++;
		addr += PAGE_SIZE;
		pte_val(entry) += PAGE_SIZE;
	}
}

/*
 * No need to decide whether this PTE shares the swap entry with others,
 * just let do_wp_page work it out if a write is requested later - to
 * force COW, vm_page_prot omits write permission from any private vma.
 */
static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
		unsigned long addr, swp_entry_t entry, struct page *page)
{
	inc_mm_counter(vma->vm_mm, anon_rss);
	get_page(page);
	set_pte_at(vma->vm_mm, addr, pte,
		   pte_mkold(mk_pte(page, vma->vm_page_prot)));
	page_add_anon_rmap(page, vma, addr);
	swap_free(entry);
	/*
	 * Move the page to the active list so it is not
	 * immediately swapped out again after swapon.
	 */
	activate_page(page);
}

static inline void io_remap_pte_range(struct mm_struct *mm, pte_t * pte, unsigned long address, unsigned long size,
	unsigned long offset, pgprot_t prot, int space)
{
	unsigned long end;

	address &= ~PMD_MASK;
	end = address + size;
	if (end > PMD_SIZE)
		end = PMD_SIZE;
	do {
		set_pte_at(mm, address, pte, mk_pte_io(offset, prot, space));
		address += PAGE_SIZE;
		offset += PAGE_SIZE;
		pte++;
	} while (address < end);
}

/*
 * set a new huge pmd. We should not be called for updating
 * an existing pmd entry. That should go via pmd_hugepage_update.
 */
void set_pmd_at(struct mm_struct *mm, unsigned long addr,
		pmd_t *pmdp, pmd_t pmd)
{
#ifdef CONFIG_DEBUG_VM
	/*
	 * Make sure hardware valid bit is not set. We don't do
	 * tlb flush for this update.
	 */

	WARN_ON(pte_hw_valid(pmd_pte(*pmdp)) && !pte_protnone(pmd_pte(*pmdp)));
	assert_spin_locked(pmd_lockptr(mm, pmdp));
	WARN_ON(!(pmd_large(pmd) || pmd_devmap(pmd)));
#endif
	trace_hugepage_set_pmd(addr, pmd_val(pmd));
	return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
}

static void ion_clean_and_init_allocated_pages(
		struct ion_system_heap *heap, struct scatterlist *sgl,
		int nents, bool memory_zero)
{
	int i;
	struct scatterlist *sg;
	size_t sum = 0;
	int page_idx;
	unsigned long vaddr;
	pte_t *ptep;

	down(&heap->vm_sem);

	page_idx = atomic_pop(&heap->page_idx, VM_PAGE_COUNT_WIDTH);
	BUG_ON((page_idx < 0) || (page_idx >= VM_PAGE_COUNT));

	ptep = heap->pte[page_idx * (SZ_1M / PAGE_SIZE)];
	vaddr = (unsigned long)heap->reserved_vm_area->addr +
				(SZ_1M * page_idx);

	for_each_sg(sgl, sg, nents, i) {
		int j;

		if (!PageHighMem(sg_page(sg))) {
			memset(page_address(sg_page(sg)), 0, sg_dma_len(sg));
			continue;
		}

		for (j = 0; j < (sg_dma_len(sg) / PAGE_SIZE); j++) {
			set_pte_at(&init_mm, vaddr, ptep,
					mk_pte(sg_page(sg) + j, PAGE_KERNEL));
			ptep++;
			vaddr += PAGE_SIZE;

		}

		sum += j * PAGE_SIZE;
		if (sum == SZ_1M) {
			ptep = heap->pte[page_idx * (SZ_1M / PAGE_SIZE)];
			vaddr = (unsigned long)heap->reserved_vm_area->addr +
						(SZ_1M * page_idx);

			ion_clean_and_unmap(vaddr, ptep, sum, memory_zero);

			sum = 0;
		}
	}

static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
		unsigned long end, unsigned long phys_addr, pgprot_t prot)
{
	pte_t *pte;
	unsigned long pfn;

	pfn = phys_addr >> PAGE_SHIFT;
	pte = pte_alloc_kernel(pmd, addr);
	if (!pte)
		return -ENOMEM;
	do {
		BUG_ON(!pte_none(*pte));
		set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
	return 0;
}

static int early_map_kernel_page(unsigned long ea, unsigned long pa,
			  pgprot_t flags,
			  unsigned int map_page_size,
			  int nid,
			  unsigned long region_start, unsigned long region_end)
{
	unsigned long pfn = pa >> PAGE_SHIFT;
	pgd_t *pgdp;
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep;

	pgdp = pgd_offset_k(ea);
	if (pgd_none(*pgdp)) {
		pudp = early_alloc_pgtable(PUD_TABLE_SIZE, nid,
						region_start, region_end);
		pgd_populate(&init_mm, pgdp, pudp);
	}
	pudp = pud_offset(pgdp, ea);
	if (map_page_size == PUD_SIZE) {
		ptep = (pte_t *)pudp;
		goto set_the_pte;
	}
	if (pud_none(*pudp)) {
		pmdp = early_alloc_pgtable(PMD_TABLE_SIZE, nid,
						region_start, region_end);
		pud_populate(&init_mm, pudp, pmdp);
	}
	pmdp = pmd_offset(pudp, ea);
	if (map_page_size == PMD_SIZE) {
		ptep = pmdp_ptep(pmdp);
		goto set_the_pte;
	}
	if (!pmd_present(*pmdp)) {
		ptep = early_alloc_pgtable(PAGE_SIZE, nid,
						region_start, region_end);
		pmd_populate_kernel(&init_mm, pmdp, ptep);
	}
	ptep = pte_offset_kernel(pmdp, ea);

set_the_pte:
	set_pte_at(&init_mm, ea, ptep, pfn_pte(pfn, flags));
	smp_wmb();
	return 0;
}

void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
{
	pte_t **ptes;
	unsigned long addr;
	unsigned long i;

	if (shared == gnttab_status_vm_area.area->addr)
		ptes = gnttab_status_vm_area.ptes;
	else
		ptes = gnttab_shared_vm_area.ptes;

	addr = (unsigned long)shared;

	for (i = 0; i < nr_gframes; i++) {
		set_pte_at(&init_mm, addr, ptes[i], __pte(0));
		addr += PAGE_SIZE;
	}
}

void *kmap_atomic(struct page *page)
{
	int idx, cpu_idx;
	unsigned long vaddr;

	preempt_disable();
	pagefault_disable();
	if (!PageHighMem(page))
		return page_address(page);

	cpu_idx = kmap_atomic_idx_push();
	idx = cpu_idx + KM_TYPE_NR * smp_processor_id();
	vaddr = FIXMAP_ADDR(idx);

	set_pte_at(&init_mm, vaddr, fixmap_page_table + idx,
	mk_pte(page, kmap_prot));

	return (void *)vaddr;
}