snapshot.c

Kernel code of linux kernel

	if (!error)
		set_bit(bit, addr);
	return error;
}

static void memory_bm_clear_bit(struct memory_bitmap *bm, unsigned long pfn)
{
	void *addr;
	unsigned int bit;
	int error;

	error = memory_bm_find_bit(bm, pfn, &addr, &bit);
	BUG_ON(error);
	clear_bit(bit, addr);
}

static int memory_bm_test_bit(struct memory_bitmap *bm, unsigned long pfn)
{
	void *addr;
	unsigned int bit;
	int error;

	error = memory_bm_find_bit(bm, pfn, &addr, &bit);
	BUG_ON(error);
	return test_bit(bit, addr);
}

/**
 *	memory_bm_next_pfn - find the pfn that corresponds to the next set bit
 *	in the bitmap @bm.  If the pfn cannot be found, BM_END_OF_MAP is
 *	returned.
 *
 *	It is required to run memory_bm_position_reset() before the first call to
 *	this function.
 */

static unsigned long memory_bm_next_pfn(struct memory_bitmap *bm)
{
	struct zone_bitmap *zone_bm;
	struct bm_block *bb;
	int bit;

	do {
		bb = bm->cur.block;
		do {
			bit = bm->cur.bit;
			bit = find_next_bit(bb->data, bm_block_bits(bb), bit);
			if (bit < bm_block_bits(bb))
				goto Return_pfn;

			bb = bb->next;
			bm->cur.block = bb;
			bm->cur.bit = 0;
		} while (bb);
		zone_bm = bm->cur.zone_bm->next;
		if (zone_bm) {
			bm->cur.zone_bm = zone_bm;
			bm->cur.block = zone_bm->bm_blocks;
			bm->cur.bit = 0;
		}
	} while (zone_bm);
	memory_bm_position_reset(bm);
	return BM_END_OF_MAP;

 Return_pfn:
	bm->cur.bit = bit + 1;
	return bb->start_pfn + bit;
}

/**
 *	This structure represents a range of page frames the contents of which
 *	should not be saved during the suspend.
 */

struct nosave_region {
	struct list_head list;
	unsigned long start_pfn;
	unsigned long end_pfn;
};

static LIST_HEAD(nosave_regions);

/**
 *	register_nosave_region - register a range of page frames the contents
 *	of which should not be saved during the suspend (to be used in the early
 *	initialization code)
 */

void __init
__register_nosave_region(unsigned long start_pfn, unsigned long end_pfn,
			 int use_kmalloc)
{
	struct nosave_region *region;

	if (start_pfn >= end_pfn)
		return;

	if (!list_empty(&nosave_regions)) {
		/* Try to extend the previous region (they should be sorted) */
		region = list_entry(nosave_regions.prev,
					struct nosave_region, list);
		if (region->end_pfn == start_pfn) {
			region->end_pfn = end_pfn;
			goto Report;
		}
	}
	if (use_kmalloc) {
		/* during init, this shouldn't fail */
		region = kmalloc(sizeof(struct nosave_region), GFP_KERNEL);
		BUG_ON(!region);
	} else
		/* This allocation cannot fail */
		region = alloc_bootmem_low(sizeof(struct nosave_region));
	region->start_pfn = start_pfn;
	region->end_pfn = end_pfn;
	list_add_tail(&region->list, &nosave_regions);
 Report:
	printk(KERN_INFO "PM: Registered nosave memory: %016lx - %016lx\n",
		start_pfn << PAGE_SHIFT, end_pfn << PAGE_SHIFT);
}

/*
 * Set bits in this map correspond to the page frames the contents of which
 * should not be saved during the suspend.
 */
static struct memory_bitmap *forbidden_pages_map;

/* Set bits in this map correspond to free page frames. */
static struct memory_bitmap *free_pages_map;

/*
 * Each page frame allocated for creating the image is marked by setting the
 * corresponding bits in forbidden_pages_map and free_pages_map simultaneously
 */

void swsusp_set_page_free(struct page *page)
{
	if (free_pages_map)
		memory_bm_set_bit(free_pages_map, page_to_pfn(page));
}

static int swsusp_page_is_free(struct page *page)
{
	return free_pages_map ?
		memory_bm_test_bit(free_pages_map, page_to_pfn(page)) : 0;
}

void swsusp_unset_page_free(struct page *page)
{
	if (free_pages_map)
		memory_bm_clear_bit(free_pages_map, page_to_pfn(page));
}

static void swsusp_set_page_forbidden(struct page *page)
{
	if (forbidden_pages_map)
		memory_bm_set_bit(forbidden_pages_map, page_to_pfn(page));
}

int swsusp_page_is_forbidden(struct page *page)
{
	return forbidden_pages_map ?
		memory_bm_test_bit(forbidden_pages_map, page_to_pfn(page)) : 0;
}

static void swsusp_unset_page_forbidden(struct page *page)
{
	if (forbidden_pages_map)
		memory_bm_clear_bit(forbidden_pages_map, page_to_pfn(page));
}

/**
 *	mark_nosave_pages - set bits corresponding to the page frames the
 *	contents of which should not be saved in a given bitmap.
 */

static void mark_nosave_pages(struct memory_bitmap *bm)
{
	struct nosave_region *region;

	if (list_empty(&nosave_regions))
		return;

	list_for_each_entry(region, &nosave_regions, list) {
		unsigned long pfn;

		pr_debug("PM: Marking nosave pages: %016lx - %016lx\n",
				region->start_pfn << PAGE_SHIFT,
				region->end_pfn << PAGE_SHIFT);

		for (pfn = region->start_pfn; pfn < region->end_pfn; pfn++)
			if (pfn_valid(pfn)) {
				/*
				 * It is safe to ignore the result of
				 * mem_bm_set_bit_check() here, since we won't
				 * touch the PFNs for which the error is
				 * returned anyway.
				 */
				mem_bm_set_bit_check(bm, pfn);
			}
	}
}

/**
 *	create_basic_memory_bitmaps - create bitmaps needed for marking page
 *	frames that should not be saved and free page frames.  The pointers
 *	forbidden_pages_map and free_pages_map are only modified if everything
 *	goes well, because we don't want the bits to be used before both bitmaps
 *	are set up.
 */

int create_basic_memory_bitmaps(void)
{
	struct memory_bitmap *bm1, *bm2;
	int error = 0;

	BUG_ON(forbidden_pages_map || free_pages_map);

	bm1 = kzalloc(sizeof(struct memory_bitmap), GFP_KERNEL);
	if (!bm1)
		return -ENOMEM;

	error = memory_bm_create(bm1, GFP_KERNEL, PG_ANY);
	if (error)
		goto Free_first_object;

	bm2 = kzalloc(sizeof(struct memory_bitmap), GFP_KERNEL);
	if (!bm2)
		goto Free_first_bitmap;

	error = memory_bm_create(bm2, GFP_KERNEL, PG_ANY);
	if (error)
		goto Free_second_object;

	forbidden_pages_map = bm1;
	free_pages_map = bm2;
	mark_nosave_pages(forbidden_pages_map);

	pr_debug("PM: Basic memory bitmaps created\n");

	return 0;

 Free_second_object:
	kfree(bm2);
 Free_first_bitmap:
 	memory_bm_free(bm1, PG_UNSAFE_CLEAR);
 Free_first_object:
	kfree(bm1);
	return -ENOMEM;
}

/**
 *	free_basic_memory_bitmaps - free memory bitmaps allocated by
 *	create_basic_memory_bitmaps().  The auxiliary pointers are necessary
 *	so that the bitmaps themselves are not referred to while they are being
 *	freed.
 */

void free_basic_memory_bitmaps(void)
{
	struct memory_bitmap *bm1, *bm2;

	BUG_ON(!(forbidden_pages_map && free_pages_map));

	bm1 = forbidden_pages_map;
	bm2 = free_pages_map;
	forbidden_pages_map = NULL;
	free_pages_map = NULL;
	memory_bm_free(bm1, PG_UNSAFE_CLEAR);
	kfree(bm1);
	memory_bm_free(bm2, PG_UNSAFE_CLEAR);
	kfree(bm2);

	pr_debug("PM: Basic memory bitmaps freed\n");
}

/**
 *	snapshot_additional_pages - estimate the number of additional pages
 *	be needed for setting up the suspend image data structures for given
 *	zone (usually the returned value is greater than the exact number)
 */

unsigned int snapshot_additional_pages(struct zone *zone)
{
	unsigned int res;

	res = DIV_ROUND_UP(zone->spanned_pages, BM_BITS_PER_BLOCK);
	res += DIV_ROUND_UP(res * sizeof(struct bm_block), PAGE_SIZE);
	return 2 * res;
}

#ifdef CONFIG_HIGHMEM
/**
 *	count_free_highmem_pages - compute the total number of free highmem
 *	pages, system-wide.
 */

static unsigned int count_free_highmem_pages(void)
{
	struct zone *zone;
	unsigned int cnt = 0;

	for_each_zone(zone)
		if (populated_zone(zone) && is_highmem(zone))
			cnt += zone_page_state(zone, NR_FREE_PAGES);

	return cnt;
}

/**
 *	saveable_highmem_page - Determine whether a highmem page should be
 *	included in the suspend image.
 *
 *	We should save the page if it isn't Nosave or NosaveFree, or Reserved,
 *	and it isn't a part of a free chunk of pages.
 */

static struct page *saveable_highmem_page(unsigned long pfn)
{
	struct page *page;

	if (!pfn_valid(pfn))
		return NULL;

	page = pfn_to_page(pfn);

	BUG_ON(!PageHighMem(page));

	if (swsusp_page_is_forbidden(page) ||  swsusp_page_is_free(page) ||
	    PageReserved(page))
		return NULL;

	return page;
}

/**
 *	count_highmem_pages - compute the total number of saveable highmem
 *	pages.
 */

unsigned int count_highmem_pages(void)
{
	struct zone *zone;
	unsigned int n = 0;

	for_each_zone(zone) {
		unsigned long pfn, max_zone_pfn;

		if (!is_highmem(zone))
			continue;

		mark_free_pages(zone);
		max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
			if (saveable_highmem_page(pfn))
				n++;
	}
	return n;
}
#else
static inline void *saveable_highmem_page(unsigned long pfn) { return NULL; }
#endif /* CONFIG_HIGHMEM */

/**
 *	saveable_page - Determine whether a non-highmem page should be included
 *	in the suspend image.
 *
 *	We should save the page if it isn't Nosave, and is not in the range
 *	of pages statically defined as 'unsaveable', and it isn't a part of
 *	a free chunk of pages.
 */

static struct page *saveable_page(unsigned long pfn)
{
	struct page *page;

	if (!pfn_valid(pfn))
		return NULL;

	page = pfn_to_page(pfn);

	BUG_ON(PageHighMem(page));

	if (swsusp_page_is_forbidden(page) || swsusp_page_is_free(page))
		return NULL;

	if (PageReserved(page)
	    && (!kernel_page_present(page) || pfn_is_nosave(pfn)))
		return NULL;

	return page;
}

/**
 *	count_data_pages - compute the total number of saveable non-highmem
 *	pages.
 */

unsigned int count_data_pages(void)
{
	struct zone *zone;
	unsigned long pfn, max_zone_pfn;
	unsigned int n = 0;

	for_each_zone(zone) {
		if (is_highmem(zone))
			continue;

		mark_free_pages(zone);
		max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
			if(saveable_page(pfn))
				n++;
	}
	return n;
}

/* This is needed, because copy_page and memcpy are not usable for copying
 * task structs.
 */
static inline void do_copy_page(long *dst, long *src)
{
	int n;

	for (n = PAGE_SIZE / sizeof(long); n; n--)
		*dst++ = *src++;
}


/**
 *	safe_copy_page - check if the page we are going to copy is marked as
 *		present in the kernel page tables (this always is the case if
 *		CONFIG_DEBUG_PAGEALLOC is not set and in that case
 *		kernel_page_present() always returns 'true').
 */
static void safe_copy_page(void *dst, struct page *s_page)
{
	if (kernel_page_present(s_page)) {
		do_copy_page(dst, page_address(s_page));
	} else {
		kernel_map_pages(s_page, 1, 1);
		do_copy_page(dst, page_address(s_page));
		kernel_map_pages(s_page, 1, 0);
	}
}


#ifdef CONFIG_HIGHMEM
static inline struct page *
page_is_saveable(struct zone *zone, unsigned long pfn)
{
	return is_highmem(zone) ?
			saveable_highmem_page(pfn) : saveable_page(pfn);
}

static void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
{
	struct page *s_page, *d_page;
	void *src, *dst;

	s_page = pfn_to_page(src_pfn);
	d_page = pfn_to_page(dst_pfn);
	if (PageHighMem(s_page)) {
		src = kmap_atomic(s_page, KM_USER0);
		dst = kmap_atomic(d_page, KM_USER1);
		do_copy_page(dst, src);
		kunmap_atomic(src, KM_USER0);
		kunmap_atomic(dst, KM_USER1);
	} else {
		if (PageHighMem(d_page)) {
			/* Page pointed to by src may contain some kernel
			 * data modified by kmap_atomic()
			 */
			safe_copy_page(buffer, s_page);
			dst = kmap_atomic(pfn_to_page(dst_pfn), KM_USER0);
			memcpy(dst, buffer, PAGE_SIZE);
			kunmap_atomic(dst, KM_USER0);
		} else {
			safe_copy_page(page_address(d_page), s_page);
		}
	}
}
#else
#define page_is_saveable(zone, pfn)	saveable_page(pfn)

static inline void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
{
	safe_copy_page(page_address(pfn_to_page(dst_pfn)),
				pfn_to_page(src_pfn));
}
#endif /* CONFIG_HIGHMEM */

static void
copy_data_pages(struct memory_bitmap *copy_bm, struct memory_bitmap *orig_bm)