Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2756 insertions, 0 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
new file mode 100644
index 000000000..03c4ca404
--- /dev/null
+++ b/kernel/power/snapshot.c
@@ -0,0 +1,2756 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/kernel/power/snapshot.c
+ *
+ * This file provides system snapshot/restore functionality for swsusp.
+ *
+ * Copyright (C) 1998-2005 Pavel Machek <pavel@ucw.cz>
+ * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
+ */
+
+#define pr_fmt(fmt) "PM: hibernation: " fmt
+
+#include <linux/version.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/suspend.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+#include <linux/spinlock.h>
+#include <linux/kernel.h>
+#include <linux/pm.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/memblock.h>
+#include <linux/nmi.h>
+#include <linux/syscalls.h>
+#include <linux/console.h>
+#include <linux/highmem.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/compiler.h>
+#include <linux/ktime.h>
+#include <linux/set_memory.h>
+
+#include <linux/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+#include <asm/io.h>
+
+#include "power.h"
+
+#if defined(CONFIG_STRICT_KERNEL_RWX) && defined(CONFIG_ARCH_HAS_SET_MEMORY)
+static bool hibernate_restore_protection;
+static bool hibernate_restore_protection_active;
+
+void enable_restore_image_protection(void)
+{
+	hibernate_restore_protection = true;
+}
+
+static inline void hibernate_restore_protection_begin(void)
+{
+	hibernate_restore_protection_active = hibernate_restore_protection;
+}
+
+static inline void hibernate_restore_protection_end(void)
+{
+	hibernate_restore_protection_active = false;
+}
+
+static inline void hibernate_restore_protect_page(void *page_address)
+{
+	if (hibernate_restore_protection_active)
+		set_memory_ro((unsigned long)page_address, 1);
+}
+
+static inline void hibernate_restore_unprotect_page(void *page_address)
+{
+	if (hibernate_restore_protection_active)
+		set_memory_rw((unsigned long)page_address, 1);
+}
+#else
+static inline void hibernate_restore_protection_begin(void) {}
+static inline void hibernate_restore_protection_end(void) {}
+static inline void hibernate_restore_protect_page(void *page_address) {}
+static inline void hibernate_restore_unprotect_page(void *page_address) {}
+#endif /* CONFIG_STRICT_KERNEL_RWX  && CONFIG_ARCH_HAS_SET_MEMORY */
+
+
+/*
+ * The calls to set_direct_map_*() should not fail because remapping a page
+ * here means that we only update protection bits in an existing PTE.
+ * It is still worth to have a warning here if something changes and this
+ * will no longer be the case.
+ */
+static inline void hibernate_map_page(struct page *page)
+{
+	if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
+		int ret = set_direct_map_default_noflush(page);
+
+		if (ret)
+			pr_warn_once("Failed to remap page\n");
+	} else {
+		debug_pagealloc_map_pages(page, 1);
+	}
+}
+
+static inline void hibernate_unmap_page(struct page *page)
+{
+	if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
+		unsigned long addr = (unsigned long)page_address(page);
+		int ret  = set_direct_map_invalid_noflush(page);
+
+		if (ret)
+			pr_warn_once("Failed to remap page\n");
+
+		flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+	} else {
+		debug_pagealloc_unmap_pages(page, 1);
+	}
+}
+
+static int swsusp_page_is_free(struct page *);
+static void swsusp_set_page_forbidden(struct page *);
+static void swsusp_unset_page_forbidden(struct page *);
+
+/*
+ * Number of bytes to reserve for memory allocations made by device drivers
+ * from their ->freeze() and ->freeze_noirq() callbacks so that they don't
+ * cause image creation to fail (tunable via /sys/power/reserved_size).
+ */
+unsigned long reserved_size;
+
+void __init hibernate_reserved_size_init(void)
+{
+	reserved_size = SPARE_PAGES * PAGE_SIZE;
+}
+
+/*
+ * Preferred image size in bytes (tunable via /sys/power/image_size).
+ * When it is set to N, swsusp will do its best to ensure the image
+ * size will not exceed N bytes, but if that is impossible, it will
+ * try to create the smallest image possible.
+ */
+unsigned long image_size;
+
+void __init hibernate_image_size_init(void)
+{
+	image_size = ((totalram_pages() * 2) / 5) * PAGE_SIZE;
+}
+
+/*
+ * List of PBEs needed for restoring the pages that were allocated before
+ * the suspend and included in the suspend image, but have also been
+ * allocated by the "resume" kernel, so their contents cannot be written
+ * directly to their "original" page frames.
+ */
+struct pbe *restore_pblist;
+
+/* struct linked_page is used to build chains of pages */
+
+#define LINKED_PAGE_DATA_SIZE	(PAGE_SIZE - sizeof(void *))
+
+struct linked_page {
+	struct linked_page *next;
+	char data[LINKED_PAGE_DATA_SIZE];
+} __packed;
+
+/*
+ * List of "safe" pages (ie. pages that were not used by the image kernel
+ * before hibernation) that may be used as temporary storage for image kernel
+ * memory contents.
+ */
+static struct linked_page *safe_pages_list;
+
+/* Pointer to an auxiliary buffer (1 page) */
+static void *buffer;
+
+#define PG_ANY		0
+#define PG_SAFE		1
+#define PG_UNSAFE_CLEAR	1
+#define PG_UNSAFE_KEEP	0
+
+static unsigned int allocated_unsafe_pages;
+
+/**
+ * get_image_page - Allocate a page for a hibernation image.
+ * @gfp_mask: GFP mask for the allocation.
+ * @safe_needed: Get pages that were not used before hibernation (restore only)
+ *
+ * During image restoration, for storing the PBE list and the image data, we can
+ * only use memory pages that do not conflict with the pages used before
+ * hibernation.  The "unsafe" pages have PageNosaveFree set and we count them
+ * using allocated_unsafe_pages.
+ *
+ * Each allocated image page is marked as PageNosave and PageNosaveFree so that
+ * swsusp_free() can release it.
+ */
+static void *get_image_page(gfp_t gfp_mask, int safe_needed)
+{
+	void *res;
+
+	res = (void *)get_zeroed_page(gfp_mask);
+	if (safe_needed)
+		while (res && swsusp_page_is_free(virt_to_page(res))) {
+			/* The page is unsafe, mark it for swsusp_free() */
+			swsusp_set_page_forbidden(virt_to_page(res));
+			allocated_unsafe_pages++;
+			res = (void *)get_zeroed_page(gfp_mask);
+		}
+	if (res) {
+		swsusp_set_page_forbidden(virt_to_page(res));
+		swsusp_set_page_free(virt_to_page(res));
+	}
+	return res;
+}
+
+static void *__get_safe_page(gfp_t gfp_mask)
+{
+	if (safe_pages_list) {
+		void *ret = safe_pages_list;
+
+		safe_pages_list = safe_pages_list->next;
+		memset(ret, 0, PAGE_SIZE);
+		return ret;
+	}
+	return get_image_page(gfp_mask, PG_SAFE);
+}
+
+unsigned long get_safe_page(gfp_t gfp_mask)
+{
+	return (unsigned long)__get_safe_page(gfp_mask);
+}
+
+static struct page *alloc_image_page(gfp_t gfp_mask)
+{
+	struct page *page;
+
+	page = alloc_page(gfp_mask);
+	if (page) {
+		swsusp_set_page_forbidden(page);
+		swsusp_set_page_free(page);
+	}
+	return page;
+}
+
+static void recycle_safe_page(void *page_address)
+{
+	struct linked_page *lp = page_address;
+
+	lp->next = safe_pages_list;
+	safe_pages_list = lp;
+}
+
+/**
+ * free_image_page - Free a page allocated for hibernation image.
+ * @addr: Address of the page to free.
+ * @clear_nosave_free: If set, clear the PageNosaveFree bit for the page.
+ *
+ * The page to free should have been allocated by get_image_page() (page flags
+ * set by it are affected).
+ */
+static inline void free_image_page(void *addr, int clear_nosave_free)
+{
+	struct page *page;
+
+	BUG_ON(!virt_addr_valid(addr));
+
+	page = virt_to_page(addr);
+
+	swsusp_unset_page_forbidden(page);
+	if (clear_nosave_free)
+		swsusp_unset_page_free(page);
+
+	__free_page(page);
+}
+
+static inline void free_list_of_pages(struct linked_page *list,
+				      int clear_page_nosave)
+{
+	while (list) {
+		struct linked_page *lp = list->next;
+
+		free_image_page(list, clear_page_nosave);
+		list = lp;
+	}
+}
+
+/*
+ * struct chain_allocator is used for allocating small objects out of
+ * a linked list of pages called 'the chain'.
+ *
+ * The chain grows each time when there is no room for a new object in
+ * the current page.  The allocated objects cannot be freed individually.
+ * It is only possible to free them all at once, by freeing the entire
+ * chain.
+ *
+ * NOTE: The chain allocator may be inefficient if the allocated objects
+ * are not much smaller than PAGE_SIZE.
+ */
+struct chain_allocator {
+	struct linked_page *chain;	/* the chain */
+	unsigned int used_space;	/* total size of objects allocated out
+					   of the current page */
+	gfp_t gfp_mask;		/* mask for allocating pages */
+	int safe_needed;	/* if set, only "safe" pages are allocated */
+};
+
+static void chain_init(struct chain_allocator *ca, gfp_t gfp_mask,
+		       int safe_needed)
+{
+	ca->chain = NULL;
+	ca->used_space = LINKED_PAGE_DATA_SIZE;
+	ca->gfp_mask = gfp_mask;
+	ca->safe_needed = safe_needed;
+}
+
+static void *chain_alloc(struct chain_allocator *ca, unsigned int size)
+{
+	void *ret;
+
+	if (LINKED_PAGE_DATA_SIZE - ca->used_space < size) {
+		struct linked_page *lp;
+
+		lp = ca->safe_needed ? __get_safe_page(ca->gfp_mask) :
+					get_image_page(ca->gfp_mask, PG_ANY);
+		if (!lp)
+			return NULL;
+
+		lp->next = ca->chain;
+		ca->chain = lp;
+		ca->used_space = 0;
+	}
+	ret = ca->chain->data + ca->used_space;
+	ca->used_space += size;
+	return ret;
+}
+
+/*
+ * Data types related to memory bitmaps.
+ *
+ * Memory bitmap is a structure consisting of many linked lists of
+ * objects.  The main list's elements are of type struct zone_bitmap
+ * and each of them corresponds to one zone.  For each zone bitmap
+ * object there is a list of objects of type struct bm_block that
+ * represent each blocks of bitmap in which information is stored.
+ *
+ * struct memory_bitmap contains a pointer to the main list of zone
+ * bitmap objects, a struct bm_position used for browsing the bitmap,
+ * and a pointer to the list of pages used for allocating all of the
+ * zone bitmap objects and bitmap block objects.
+ *
+ * NOTE: It has to be possible to lay out the bitmap in memory
+ * using only allocations of order 0.  Additionally, the bitmap is
+ * designed to work with arbitrary number of zones (this is over the
+ * top for now, but let's avoid making unnecessary assumptions ;-).
+ *
+ * struct zone_bitmap contains a pointer to a list of bitmap block
+ * objects and a pointer to the bitmap block object that has been
+ * most recently used for setting bits.  Additionally, it contains the
+ * PFNs that correspond to the start and end of the represented zone.
+ *
+ * struct bm_block contains a pointer to the memory page in which
+ * information is stored (in the form of a block of bitmap)
+ * It also contains the pfns that correspond to the start and end of
+ * the represented memory area.
+ *
+ * The memory bitmap is organized as a radix tree to guarantee fast random
+ * access to the bits. There is one radix tree for each zone (as returned
+ * from create_mem_extents).
+ *
+ * One radix tree is represented by one struct mem_zone_bm_rtree. There are
+ * two linked lists for the nodes of the tree, one for the inner nodes and
+ * one for the leave nodes. The linked leave nodes are used for fast linear
+ * access of the memory bitmap.
+ *
+ * The struct rtree_node represents one node of the radix tree.
+ */
+
+#define BM_END_OF_MAP	(~0UL)
+
+#define BM_BITS_PER_BLOCK	(PAGE_SIZE * BITS_PER_BYTE)
+#define BM_BLOCK_SHIFT		(PAGE_SHIFT + 3)
+#define BM_BLOCK_MASK		((1UL << BM_BLOCK_SHIFT) - 1)
+
+/*
+ * struct rtree_node is a wrapper struct to link the nodes
+ * of the rtree together for easy linear iteration over
+ * bits and easy freeing
+ */
+struct rtree_node {
+	struct list_head list;
+	unsigned long *data;
+};
+
+/*
+ * struct mem_zone_bm_rtree represents a bitmap used for one
+ * populated memory zone.
+ */
+struct mem_zone_bm_rtree {
+	struct list_head list;		/* Link Zones together         */
+	struct list_head nodes;		/* Radix Tree inner nodes      */
+	struct list_head leaves;	/* Radix Tree leaves           */
+	unsigned long start_pfn;	/* Zone start page frame       */
+	unsigned long end_pfn;		/* Zone end page frame + 1     */
+	struct rtree_node *rtree;	/* Radix Tree Root             */
+	int levels;			/* Number of Radix Tree Levels */
+	unsigned int blocks;		/* Number of Bitmap Blocks     */
+};
+
+/* strcut bm_position is used for browsing memory bitmaps */
+
+struct bm_position {
+	struct mem_zone_bm_rtree *zone;
+	struct rtree_node *node;
+	unsigned long node_pfn;
+	int node_bit;
+};
+
+struct memory_bitmap {
+	struct list_head zones;
+	struct linked_page *p_list;	/* list of pages used to store zone
+					   bitmap objects and bitmap block
+					   objects */
+	struct bm_position cur;	/* most recently used bit position */
+};
+
+/* Functions that operate on memory bitmaps */
+
+#define BM_ENTRIES_PER_LEVEL	(PAGE_SIZE / sizeof(unsigned long))
+#if BITS_PER_LONG == 32
+#define BM_RTREE_LEVEL_SHIFT	(PAGE_SHIFT - 2)
+#else
+#define BM_RTREE_LEVEL_SHIFT	(PAGE_SHIFT - 3)
+#endif
+#define BM_RTREE_LEVEL_MASK	((1UL << BM_RTREE_LEVEL_SHIFT) - 1)
+
+/**
+ * alloc_rtree_node - Allocate a new node and add it to the radix tree.
+ * @gfp_mask: GFP mask for the allocation.
+ * @safe_needed: Get pages not used before hibernation (restore only)
+ * @ca: Pointer to a linked list of pages ("a chain") to allocate from
+ * @list: Radix Tree node to add.
+ *
+ * This function is used to allocate inner nodes as well as the
+ * leave nodes of the radix tree. It also adds the node to the
+ * corresponding linked list passed in by the *list parameter.
+ */
+static struct rtree_node *alloc_rtree_node(gfp_t gfp_mask, int safe_needed,
+					   struct chain_allocator *ca,
+					   struct list_head *list)
+{
+	struct rtree_node *node;
+
+	node = chain_alloc(ca, sizeof(struct rtree_node));
+	if (!node)
+		return NULL;
+
+	node->data = get_image_page(gfp_mask, safe_needed);
+	if (!node->data)
+		return NULL;
+
+	list_add_tail(&node->list, list);
+
+	return node;
+}
+
+/**
+ * add_rtree_block - Add a new leave node to the radix tree.
+ *
+ * The leave nodes need to be allocated in order to keep the leaves
+ * linked list in order. This is guaranteed by the zone->blocks
+ * counter.
+ */
+static int add_rtree_block(struct mem_zone_bm_rtree *zone, gfp_t gfp_mask,
+			   int safe_needed, struct chain_allocator *ca)
+{
+	struct rtree_node *node, *block, **dst;
+	unsigned int levels_needed, block_nr;
+	int i;
+
+	block_nr = zone->blocks;
+	levels_needed = 0;
+
+	/* How many levels do we need for this block nr? */
+	while (block_nr) {
+		levels_needed += 1;
+		block_nr >>= BM_RTREE_LEVEL_SHIFT;
+	}
+
+	/* Make sure the rtree has enough levels */
+	for (i = zone->levels; i < levels_needed; i++) {
+		node = alloc_rtree_node(gfp_mask, safe_needed, ca,
+					&zone->nodes);
+		if (!node)
+			return -ENOMEM;
+
+		node->data[0] = (unsigned long)zone->rtree;
+		zone->rtree = node;
+		zone->levels += 1;
+	}
+
+	/* Allocate new block */
+	block = alloc_rtree_node(gfp_mask, safe_needed, ca, &zone->leaves);
+	if (!block)
+		return -ENOMEM;
+
+	/* Now walk the rtree to insert the block */
+	node = zone->rtree;
+	dst = &zone->rtree;
+	block_nr = zone->blocks;
+	for (i = zone->levels; i > 0; i--) {
+		int index;
+
+		if (!node) {
+			node = alloc_rtree_node(gfp_mask, safe_needed, ca,
+						&zone->nodes);
+			if (!node)
+				return -ENOMEM;
+			*dst = node;
+		}
+
+		index = block_nr >> ((i - 1) * BM_RTREE_LEVEL_SHIFT);
+		index &= BM_RTREE_LEVEL_MASK;
+		dst = (struct rtree_node **)&((*dst)->data[index]);
+		node = *dst;
+	}
+
+	zone->blocks += 1;
+	*dst = block;
+
+	return 0;
+}
+
+static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
+			       int clear_nosave_free);
+
+/**
+ * create_zone_bm_rtree - Create a radix tree for one zone.
+ *
+ * Allocated the mem_zone_bm_rtree structure and initializes it.
+ * This function also allocated and builds the radix tree for the
+ * zone.
+ */
+static struct mem_zone_bm_rtree *create_zone_bm_rtree(gfp_t gfp_mask,
+						      int safe_needed,
+						      struct chain_allocator *ca,
+						      unsigned long start,
+						      unsigned long end)
+{
+	struct mem_zone_bm_rtree *zone;
+	unsigned int i, nr_blocks;
+	unsigned long pages;
+
+	pages = end - start;
+	zone  = chain_alloc(ca, sizeof(struct mem_zone_bm_rtree));
+	if (!zone)
+		return NULL;
+
+	INIT_LIST_HEAD(&zone->nodes);
+	INIT_LIST_HEAD(&zone->leaves);
+	zone->start_pfn = start;
+	zone->end_pfn = end;
+	nr_blocks = DIV_ROUND_UP(pages, BM_BITS_PER_BLOCK);
+
+	for (i = 0; i < nr_blocks; i++) {
+		if (add_rtree_block(zone, gfp_mask, safe_needed, ca)) {
+			free_zone_bm_rtree(zone, PG_UNSAFE_CLEAR);
+			return NULL;
+		}
+	}
+
+	return zone;
+}
+
+/**
+ * free_zone_bm_rtree - Free the memory of the radix tree.
+ *
+ * Free all node pages of the radix tree. The mem_zone_bm_rtree
+ * structure itself is not freed here nor are the rtree_node
+ * structs.
+ */
+static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
+			       int clear_nosave_free)
+{
+	struct rtree_node *node;
+
+	list_for_each_entry(node, &zone->nodes, list)
+		free_image_page(node->data, clear_nosave_free);
+
+	list_for_each_entry(node, &zone->leaves, list)
+		free_image_page(node->data, clear_nosave_free);
+}
+
+static void memory_bm_position_reset(struct memory_bitmap *bm)
+{
+	bm->cur.zone = list_entry(bm->zones.next, struct mem_zone_bm_rtree,
+				  list);
+	bm->cur.node = list_entry(bm->cur.zone->leaves.next,
+				  struct rtree_node, list);
+	bm->cur.node_pfn = 0;
+	bm->cur.node_bit = 0;
+}
+
+static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free);
+
+struct mem_extent {
+	struct list_head hook;
+	unsigned long start;
+	unsigned long end;
+};
+
+/**
+ * free_mem_extents - Free a list of memory extents.
+ * @list: List of extents to free.
+ */
+static void free_mem_extents(struct list_head *list)
+{
+	struct mem_extent *ext, *aux;
+
+	list_for_each_entry_safe(ext, aux, list, hook) {
+		list_del(&ext->hook);
+		kfree(ext);
+	}
+}
+
+/**
+ * create_mem_extents - Create a list of memory extents.
+ * @list: List to put the extents into.
+ * @gfp_mask: Mask to use for memory allocations.
+ *
+ * The extents represent contiguous ranges of PFNs.
+ */
+static int create_mem_extents(struct list_head *list, gfp_t gfp_mask)
+{
+	struct zone *zone;
+
+	INIT_LIST_HEAD(list);
+
+	for_each_populated_zone(zone) {
+		unsigned long zone_start, zone_end;
+		struct mem_extent *ext, *cur, *aux;
+
+		zone_start = zone->zone_start_pfn;
+		zone_end = zone_end_pfn(zone);
+
+		list_for_each_entry(ext, list, hook)
+			if (zone_start <= ext->end)
+				break;
+
+		if (&ext->hook == list || zone_end < ext->start) {
+			/* New extent is necessary */
+			struct mem_extent *new_ext;
+
+			new_ext = kzalloc(sizeof(struct mem_extent), gfp_mask);
+			if (!new_ext) {
+				free_mem_extents(list);
+				return -ENOMEM;
+			}
+			new_ext->start = zone_start;
+			new_ext->end = zone_end;
+			list_add_tail(&new_ext->hook, &ext->hook);
+			continue;
+		}
+
+		/* Merge this zone's range of PFNs with the existing one */
+		if (zone_start < ext->start)
+			ext->start = zone_start;
+		if (zone_end > ext->end)
+			ext->end = zone_end;
+
+		/* More merging may be possible */
+		cur = ext;
+		list_for_each_entry_safe_continue(cur, aux, list, hook) {
+			if (zone_end < cur->start)
+				break;
+			if (zone_end < cur->end)
+				ext->end = cur->end;
+			list_del(&cur->hook);
+			kfree(cur);
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * memory_bm_create - Allocate memory for a memory bitmap.
+ */
+static int memory_bm_create(struct memory_bitmap *bm, gfp_t gfp_mask,
+			    int safe_needed)
+{
+	struct chain_allocator ca;
+	struct list_head mem_extents;
+	struct mem_extent *ext;
+	int error;
+
+	chain_init(&ca, gfp_mask, safe_needed);
+	INIT_LIST_HEAD(&bm->zones);
+
+	error = create_mem_extents(&mem_extents, gfp_mask);
+	if (error)
+		return error;
+
+	list_for_each_entry(ext, &mem_extents, hook) {
+		struct mem_zone_bm_rtree *zone;
+
+		zone = create_zone_bm_rtree(gfp_mask, safe_needed, &ca,
+					    ext->start, ext->end);
+		if (!zone) {
+			error = -ENOMEM;
+			goto Error;
+		}
+		list_add_tail(&zone->list, &bm->zones);
+	}
+
+	bm->p_list = ca.chain;
+	memory_bm_position_reset(bm);
+ Exit:
+	free_mem_extents(&mem_extents);
+	return error;
+
+ Error:
+	bm->p_list = ca.chain;
+	memory_bm_free(bm, PG_UNSAFE_CLEAR);
+	goto Exit;
+}
+
+/**
+ * memory_bm_free - Free memory occupied by the memory bitmap.
+ * @bm: Memory bitmap.
+ */
+static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free)
+{
+	struct mem_zone_bm_rtree *zone;
+
+	list_for_each_entry(zone, &bm->zones, list)
+		free_zone_bm_rtree(zone, clear_nosave_free);
+
+	free_list_of_pages(bm->p_list, clear_nosave_free);
+
+	INIT_LIST_HEAD(&bm->zones);
+}
+
+/**
+ * memory_bm_find_bit - Find the bit for a given PFN in a memory bitmap.
+ *
+ * Find the bit in memory bitmap @bm that corresponds to the given PFN.
+ * The cur.zone, cur.block and cur.node_pfn members of @bm are updated.
+ *
+ * Walk the radix tree to find the page containing the bit that represents @pfn
+ * and return the position of the bit in @addr and @bit_nr.
+ */
+static int memory_bm_find_bit(struct memory_bitmap *bm, unsigned long pfn,
+			      void **addr, unsigned int *bit_nr)
+{
+	struct mem_zone_bm_rtree *curr, *zone;
+	struct rtree_node *node;
+	int i, block_nr;
+
+	zone = bm->cur.zone;
+
+	if (pfn >= zone->start_pfn && pfn < zone->end_pfn)
+		goto zone_found;
+
+	zone = NULL;
+
+	/* Find the right zone */
+	list_for_each_entry(curr, &bm->zones, list) {
+		if (pfn >= curr->start_pfn && pfn < curr->end_pfn) {
+			zone = curr;
+			break;
+		}
+	}
+
+	if (!zone)
+		return -EFAULT;
+
+zone_found:
+	/*
+	 * We have found the zone. Now walk the radix tree to find the leaf node
+	 * for our PFN.
+	 */
+
+	/*
+	 * If the zone we wish to scan is the current zone and the
+	 * pfn falls into the current node then we do not need to walk
+	 * the tree.
+	 */
+	node = bm->cur.node;
+	if (zone == bm->cur.zone &&
+	    ((pfn - zone->start_pfn) & ~BM_BLOCK_MASK) == bm->cur.node_pfn)
+		goto node_found;
+
+	node      = zone->rtree;
+	block_nr  = (pfn - zone->start_pfn) >> BM_BLOCK_SHIFT;
+
+	for (i = zone->levels; i > 0; i--) {
+		int index;
+
+		index = block_nr >> ((i - 1) * BM_RTREE_LEVEL_SHIFT);
+		index &= BM_RTREE_LEVEL_MASK;
+		BUG_ON(node->data[index] == 0);
+		node = (struct rtree_node *)node->data[index];
+	}
+
+node_found:
+	/* Update last position */
+	bm->cur.zone = zone;
+	bm->cur.node = node;
+	bm->cur.node_pfn = (pfn - zone->start_pfn) & ~BM_BLOCK_MASK;
+
+	/* Set return values */
+	*addr = node->data;
+	*bit_nr = (pfn - zone->start_pfn) & BM_BLOCK_MASK;
+
+	return 0;
+}
+
+static void memory_bm_set_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);
+	set_bit(bit, addr);
+}
+
+static int mem_bm_set_bit_check(struct memory_bitmap *bm, unsigned long pfn)
+{
+	void *addr;
+	unsigned int bit;
+	int error;
+
+	error = memory_bm_find_bit(bm, pfn, &addr, &bit);
+	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 void memory_bm_clear_current(struct memory_bitmap *bm)
+{
+	int bit;
+
+	bit = max(bm->cur.node_bit - 1, 0);
+	clear_bit(bit, bm->cur.node->data);
+}
+
+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);
+}
+
+static bool memory_bm_pfn_present(struct memory_bitmap *bm, unsigned long pfn)
+{
+	void *addr;
+	unsigned int bit;
+
+	return !memory_bm_find_bit(bm, pfn, &addr, &bit);
+}
+
+/*
+ * rtree_next_node - Jump to the next leaf node.
+ *
+ * Set the position to the beginning of the next node in the
+ * memory bitmap. This is either the next node in the current
+ * zone's radix tree or the first node in the radix tree of the
+ * next zone.
+ *
+ * Return true if there is a next node, false otherwise.
+ */
+static bool rtree_next_node(struct memory_bitmap *bm)
+{
+	if (!list_is_last(&bm->cur.node->list, &bm->cur.zone->leaves)) {
+		bm->cur.node = list_entry(bm->cur.node->list.next,
+					  struct rtree_node, list);
+		bm->cur.node_pfn += BM_BITS_PER_BLOCK;
+		bm->cur.node_bit  = 0;
+		touch_softlockup_watchdog();
+		return true;
+	}
+
+	/* No more nodes, goto next zone */
+	if (!list_is_last(&bm->cur.zone->list, &bm->zones)) {
+		bm->cur.zone = list_entry(bm->cur.zone->list.next,
+				  struct mem_zone_bm_rtree, list);
+		bm->cur.node = list_entry(bm->cur.zone->leaves.next,
+					  struct rtree_node, list);
+		bm->cur.node_pfn = 0;
+		bm->cur.node_bit = 0;
+		return true;
+	}
+
+	/* No more zones */
+	return false;
+}
+
+/**
+ * memory_bm_next_pfn - Find the next set bit in a memory bitmap.
+ * @bm: Memory bitmap.
+ *
+ * Starting from the last returned position this function searches for the next
+ * set bit in @bm and returns the PFN represented by it.  If no more bits are
+ * set, BM_END_OF_MAP is returned.
+ *
+ * It is required to run memory_bm_position_reset() before the first call to
+ * this function for the given memory bitmap.
+ */
+static unsigned long memory_bm_next_pfn(struct memory_bitmap *bm)
+{
+	unsigned long bits, pfn, pages;
+	int bit;
+
+	do {
+		pages	  = bm->cur.zone->end_pfn - bm->cur.zone->start_pfn;
+		bits      = min(pages - bm->cur.node_pfn, BM_BITS_PER_BLOCK);
+		bit	  = find_next_bit(bm->cur.node->data, bits,
+					  bm->cur.node_bit);
+		if (bit < bits) {
+			pfn = bm->cur.zone->start_pfn + bm->cur.node_pfn + bit;
+			bm->cur.node_bit = bit + 1;
+			return pfn;
+		}
+	} while (rtree_next_node(bm));
+
+	return BM_END_OF_MAP;
+}
+
+/*
+ * This structure represents a range of page frames the contents of which
+ * should not be saved during hibernation.
+ */
+struct nosave_region {
+	struct list_head list;
+	unsigned long start_pfn;
+	unsigned long end_pfn;
+};
+
+static LIST_HEAD(nosave_regions);
+
+static void recycle_zone_bm_rtree(struct mem_zone_bm_rtree *zone)
+{
+	struct rtree_node *node;
+
+	list_for_each_entry(node, &zone->nodes, list)
+		recycle_safe_page(node->data);
+
+	list_for_each_entry(node, &zone->leaves, list)
+		recycle_safe_page(node->data);
+}
+
+static void memory_bm_recycle(struct memory_bitmap *bm)
+{
+	struct mem_zone_bm_rtree *zone;
+	struct linked_page *p_list;
+
+	list_for_each_entry(zone, &bm->zones, list)
+		recycle_zone_bm_rtree(zone);
+
+	p_list = bm->p_list;
+	while (p_list) {
+		struct linked_page *lp = p_list;
+
+		p_list = lp->next;
+		recycle_safe_page(lp);
+	}
+}
+
+/**
+ * register_nosave_region - Register a region of unsaveable memory.
+ *
+ * Register a range of page frames the contents of which should not be saved
+ * during hibernation (to be used in the early initialization code).
+ */
+void __init register_nosave_region(unsigned long start_pfn, unsigned long end_pfn)
+{
+	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;
+		}
+	}
+	/* This allocation cannot fail */
+	region = memblock_alloc(sizeof(struct nosave_region),
+				SMP_CACHE_BYTES);
+	if (!region)
+		panic("%s: Failed to allocate %zu bytes\n", __func__,
+		      sizeof(struct nosave_region));
+	region->start_pfn = start_pfn;
+	region->end_pfn = end_pfn;
+	list_add_tail(&region->list, &nosave_regions);
+ Report:
+	pr_info("Registered nosave memory: [mem %#010llx-%#010llx]\n",
+		(unsigned long long) start_pfn << PAGE_SHIFT,
+		((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
+}
+
+/*
+ * 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 - Mark pages that should not be saved.
+ * @bm: Memory bitmap.
+ *
+ * Set the bits in @bm that correspond to the page frames the contents of which
+ * should not be saved.
+ */
+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("Marking nosave pages: [mem %#010llx-%#010llx]\n",
+			 (unsigned long long) region->start_pfn << PAGE_SHIFT,
+			 ((unsigned long long) region->end_pfn << PAGE_SHIFT)
+				- 1);
+
+		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 to hold basic page information.
+ *
+ * Create bitmaps needed for marking page frames that should not be saved and
+ * free page frames.  The forbidden_pages_map and free_pages_map pointers are
+ * only modified if everything goes well, because we don't want the bits to be
+ * touched before both bitmaps are set up.
+ */
+int create_basic_memory_bitmaps(void)
+{
+	struct memory_bitmap *bm1, *bm2;
+	int error = 0;
+
+	if (forbidden_pages_map && free_pages_map)
+		return 0;
+	else
+		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("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 holding basic information.
+ *
+ * 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;
+
+	if (WARN_ON(!(forbidden_pages_map && free_pages_map)))
+		return;
+
+	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("Basic memory bitmaps freed\n");
+}
+
+static void clear_or_poison_free_page(struct page *page)
+{
+	if (page_poisoning_enabled_static())
+		__kernel_poison_pages(page, 1);
+	else if (want_init_on_free())
+		clear_highpage(page);
+}
+
+void clear_or_poison_free_pages(void)
+{
+	struct memory_bitmap *bm = free_pages_map;
+	unsigned long pfn;
+
+	if (WARN_ON(!(free_pages_map)))
+		return;
+
+	if (page_poisoning_enabled() || want_init_on_free()) {
+		memory_bm_position_reset(bm);
+		pfn = memory_bm_next_pfn(bm);
+		while (pfn != BM_END_OF_MAP) {
+			if (pfn_valid(pfn))
+				clear_or_poison_free_page(pfn_to_page(pfn));
+
+			pfn = memory_bm_next_pfn(bm);
+		}
+		memory_bm_position_reset(bm);
+		pr_info("free pages cleared after restore\n");
+	}
+}
+
+/**
+ * snapshot_additional_pages - Estimate the number of extra pages needed.
+ * @zone: Memory zone to carry out the computation for.
+ *
+ * Estimate the number of additional pages needed for setting up a hibernation
+ * image data structures for @zone (usually, the returned value is greater than
+ * the exact number).
+ */
+unsigned int snapshot_additional_pages(struct zone *zone)
+{
+	unsigned int rtree, nodes;
+
+	rtree = nodes = DIV_ROUND_UP(zone->spanned_pages, BM_BITS_PER_BLOCK);
+	rtree += DIV_ROUND_UP(rtree * sizeof(struct rtree_node),
+			      LINKED_PAGE_DATA_SIZE);
+	while (nodes > 1) {
+		nodes = DIV_ROUND_UP(nodes, BM_ENTRIES_PER_LEVEL);
+		rtree += nodes;
+	}
+
+	return 2 * rtree;
+}
+
+#ifdef CONFIG_HIGHMEM
+/**
+ * count_free_highmem_pages - Compute the total number of free highmem pages.
+ *
+ * The returned number is system-wide.
+ */
+static unsigned int count_free_highmem_pages(void)
+{
+	struct zone *zone;
+	unsigned int cnt = 0;
+
+	for_each_populated_zone(zone)
+		if (is_highmem(zone))
+			cnt += zone_page_state(zone, NR_FREE_PAGES);
+
+	return cnt;
+}
+
+/**
+ * saveable_highmem_page - Check if a highmem page is saveable.
+ *
+ * Determine whether a highmem page should be included in a hibernation image.
+ *
+ * We should save the page if it isn't Nosave or NosaveFree, or Reserved,
+ * and it isn't part of a free chunk of pages.
+ */
+static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
+{
+	struct page *page;
+
+	if (!pfn_valid(pfn))
+		return NULL;
+
+	page = pfn_to_online_page(pfn);
+	if (!page || page_zone(page) != zone)
+		return NULL;
+
+	BUG_ON(!PageHighMem(page));
+
+	if (swsusp_page_is_forbidden(page) ||  swsusp_page_is_free(page))
+		return NULL;
+
+	if (PageReserved(page) || PageOffline(page))
+		return NULL;
+
+	if (page_is_guard(page))
+		return NULL;
+
+	return page;
+}
+
+/**
+ * count_highmem_pages - Compute the total number of saveable highmem pages.
+ */
+static unsigned int count_highmem_pages(void)
+{
+	struct zone *zone;
+	unsigned int n = 0;
+
+	for_each_populated_zone(zone) {
+		unsigned long pfn, max_zone_pfn;
+
+		if (!is_highmem(zone))
+			continue;
+
+		mark_free_pages(zone);
+		max_zone_pfn = zone_end_pfn(zone);
+		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
+			if (saveable_highmem_page(zone, pfn))
+				n++;
+	}
+	return n;
+}
+#else
+static inline void *saveable_highmem_page(struct zone *z, unsigned long p)
+{
+	return NULL;
+}
+#endif /* CONFIG_HIGHMEM */
+
+/**
+ * saveable_page - Check if the given page is saveable.
+ *
+ * Determine whether a non-highmem page should be included in a hibernation
+ * 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 part of
+ * a free chunk of pages.
+ */
+static struct page *saveable_page(struct zone *zone, unsigned long pfn)
+{
+	struct page *page;
+
+	if (!pfn_valid(pfn))
+		return NULL;
+
+	page = pfn_to_online_page(pfn);
+	if (!page || page_zone(page) != zone)
+		return NULL;
+
+	BUG_ON(PageHighMem(page));
+
+	if (swsusp_page_is_forbidden(page) || swsusp_page_is_free(page))
+		return NULL;
+
+	if (PageOffline(page))
+		return NULL;
+
+	if (PageReserved(page)
+	    && (!kernel_page_present(page) || pfn_is_nosave(pfn)))
+		return NULL;
+
+	if (page_is_guard(page))
+		return NULL;
+
+	return page;
+}
+
+/**
+ * count_data_pages - Compute the total number of saveable non-highmem pages.
+ */
+static unsigned int count_data_pages(void)
+{
+	struct zone *zone;
+	unsigned long pfn, max_zone_pfn;
+	unsigned int n = 0;
+
+	for_each_populated_zone(zone) {
+		if (is_highmem(zone))
+			continue;
+
+		mark_free_pages(zone);
+		max_zone_pfn = zone_end_pfn(zone);
+		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
+			if (saveable_page(zone, 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 - Copy a page in a safe way.
+ *
+ * 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 or
+ * CONFIG_ARCH_HAS_SET_DIRECT_MAP is not set. 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 {
+		hibernate_map_page(s_page);
+		do_copy_page(dst, page_address(s_page));
+		hibernate_unmap_page(s_page);
+	}
+}
+
+#ifdef CONFIG_HIGHMEM
+static inline struct page *page_is_saveable(struct zone *zone, unsigned long pfn)
+{
+	return is_highmem(zone) ?
+		saveable_highmem_page(zone, pfn) : saveable_page(zone, 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);
+		dst = kmap_atomic(d_page);
+		do_copy_page(dst, src);
+		kunmap_atomic(dst);
+		kunmap_atomic(src);
+	} else {
+		if (PageHighMem(d_page)) {
+			/*
+			 * The page pointed to by src may contain some kernel
+			 * data modified by kmap_atomic()
+			 */
+			safe_copy_page(buffer, s_page);
+			dst = kmap_atomic(d_page);
+			copy_page(dst, buffer);
+			kunmap_atomic(dst);
+		} else {
+			safe_copy_page(page_address(d_page), s_page);
+		}
+	}
+}
+#else
+#define page_is_saveable(zone, pfn)	saveable_page(zone, 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)
+{
+	struct zone *zone;
+	unsigned long pfn;
+
+	for_each_populated_zone(zone) {
+		unsigned long max_zone_pfn;
+
+		mark_free_pages(zone);
+		max_zone_pfn = zone_end_pfn(zone);
+		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
+			if (page_is_saveable(zone, pfn))
+				memory_bm_set_bit(orig_bm, pfn);
+	}
+	memory_bm_position_reset(orig_bm);
+	memory_bm_position_reset(copy_bm);
+	for(;;) {
+		pfn = memory_bm_next_pfn(orig_bm);
+		if (unlikely(pfn == BM_END_OF_MAP))
+			break;
+		copy_data_page(memory_bm_next_pfn(copy_bm), pfn);
+	}
+}
+
+/* Total number of image pages */
+static unsigned int nr_copy_pages;
+/* Number of pages needed for saving the original pfns of the image pages */
+static unsigned int nr_meta_pages;
+/*
+ * Numbers of normal and highmem page frames allocated for hibernation image
+ * before suspending devices.
+ */
+static unsigned int alloc_normal, alloc_highmem;
+/*
+ * Memory bitmap used for marking saveable pages (during hibernation) or
+ * hibernation image pages (during restore)
+ */
+static struct memory_bitmap orig_bm;
+/*
+ * Memory bitmap used during hibernation for marking allocated page frames that
+ * will contain copies of saveable pages.  During restore it is initially used
+ * for marking hibernation image pages, but then the set bits from it are
+ * duplicated in @orig_bm and it is released.  On highmem systems it is next
+ * used for marking "safe" highmem pages, but it has to be reinitialized for
+ * this purpose.
+ */
+static struct memory_bitmap copy_bm;
+
+/**
+ * swsusp_free - Free pages allocated for hibernation image.
+ *
+ * Image pages are allocated before snapshot creation, so they need to be
+ * released after resume.
+ */
+void swsusp_free(void)
+{
+	unsigned long fb_pfn, fr_pfn;
+
+	if (!forbidden_pages_map || !free_pages_map)
+		goto out;
+
+	memory_bm_position_reset(forbidden_pages_map);
+	memory_bm_position_reset(free_pages_map);
+
+loop:
+	fr_pfn = memory_bm_next_pfn(free_pages_map);
+	fb_pfn = memory_bm_next_pfn(forbidden_pages_map);
+
+	/*
+	 * Find the next bit set in both bitmaps. This is guaranteed to
+	 * terminate when fb_pfn == fr_pfn == BM_END_OF_MAP.
+	 */
+	do {
+		if (fb_pfn < fr_pfn)
+			fb_pfn = memory_bm_next_pfn(forbidden_pages_map);
+		if (fr_pfn < fb_pfn)
+			fr_pfn = memory_bm_next_pfn(free_pages_map);
+	} while (fb_pfn != fr_pfn);
+
+	if (fr_pfn != BM_END_OF_MAP && pfn_valid(fr_pfn)) {
+		struct page *page = pfn_to_page(fr_pfn);
+
+		memory_bm_clear_current(forbidden_pages_map);
+		memory_bm_clear_current(free_pages_map);
+		hibernate_restore_unprotect_page(page_address(page));
+		__free_page(page);
+		goto loop;
+	}
+
+out:
+	nr_copy_pages = 0;
+	nr_meta_pages = 0;
+	restore_pblist = NULL;
+	buffer = NULL;
+	alloc_normal = 0;
+	alloc_highmem = 0;
+	hibernate_restore_protection_end();
+}
+
+/* Helper functions used for the shrinking of memory. */
+
+#define GFP_IMAGE	(GFP_KERNEL | __GFP_NOWARN)
+
+/**
+ * preallocate_image_pages - Allocate a number of pages for hibernation image.
+ * @nr_pages: Number of page frames to allocate.
+ * @mask: GFP flags to use for the allocation.
+ *
+ * Return value: Number of page frames actually allocated
+ */
+static unsigned long preallocate_image_pages(unsigned long nr_pages, gfp_t mask)
+{
+	unsigned long nr_alloc = 0;
+
+	while (nr_pages > 0) {
+		struct page *page;
+
+		page = alloc_image_page(mask);
+		if (!page)
+			break;
+		memory_bm_set_bit(&copy_bm, page_to_pfn(page));
+		if (PageHighMem(page))
+			alloc_highmem++;
+		else
+			alloc_normal++;
+		nr_pages--;
+		nr_alloc++;
+	}
+
+	return nr_alloc;
+}
+
+static unsigned long preallocate_image_memory(unsigned long nr_pages,
+					      unsigned long avail_normal)
+{
+	unsigned long alloc;
+
+	if (avail_normal <= alloc_normal)
+		return 0;
+
+	alloc = avail_normal - alloc_normal;
+	if (nr_pages < alloc)
+		alloc = nr_pages;
+
+	return preallocate_image_pages(alloc, GFP_IMAGE);
+}
+
+#ifdef CONFIG_HIGHMEM
+static unsigned long preallocate_image_highmem(unsigned long nr_pages)
+{
+	return preallocate_image_pages(nr_pages, GFP_IMAGE | __GFP_HIGHMEM);
+}
+
+/**
+ *  __fraction - Compute (an approximation of) x * (multiplier / base).
+ */
+static unsigned long __fraction(u64 x, u64 multiplier, u64 base)
+{
+	return div64_u64(x * multiplier, base);
+}
+
+static unsigned long preallocate_highmem_fraction(unsigned long nr_pages,
+						  unsigned long highmem,
+						  unsigned long total)
+{
+	unsigned long alloc = __fraction(nr_pages, highmem, total);
+
+	return preallocate_image_pages(alloc, GFP_IMAGE | __GFP_HIGHMEM);
+}
+#else /* CONFIG_HIGHMEM */
+static inline unsigned long preallocate_image_highmem(unsigned long nr_pages)
+{
+	return 0;
+}
+
+static inline unsigned long preallocate_highmem_fraction(unsigned long nr_pages,
+							 unsigned long highmem,
+							 unsigned long total)
+{
+	return 0;
+}
+#endif /* CONFIG_HIGHMEM */
+
+/**
+ * free_unnecessary_pages - Release preallocated pages not needed for the image.
+ */
+static unsigned long free_unnecessary_pages(void)
+{
+	unsigned long save, to_free_normal, to_free_highmem, free;
+
+	save = count_data_pages();
+	if (alloc_normal >= save) {
+		to_free_normal = alloc_normal - save;
+		save = 0;
+	} else {
+		to_free_normal = 0;
+		save -= alloc_normal;
+	}
+	save += count_highmem_pages();
+	if (alloc_highmem >= save) {
+		to_free_highmem = alloc_highmem - save;
+	} else {
+		to_free_highmem = 0;
+		save -= alloc_highmem;
+		if (to_free_normal > save)
+			to_free_normal -= save;
+		else
+			to_free_normal = 0;
+	}
+	free = to_free_normal + to_free_highmem;
+
+	memory_bm_position_reset(&copy_bm);
+
+	while (to_free_normal > 0 || to_free_highmem > 0) {
+		unsigned long pfn = memory_bm_next_pfn(&copy_bm);
+		struct page *page = pfn_to_page(pfn);
+
+		if (PageHighMem(page)) {
+			if (!to_free_highmem)
+				continue;
+			to_free_highmem--;
+			alloc_highmem--;
+		} else {
+			if (!to_free_normal)
+				continue;
+			to_free_normal--;
+			alloc_normal--;
+		}
+		memory_bm_clear_bit(&copy_bm, pfn);
+		swsusp_unset_page_forbidden(page);
+		swsusp_unset_page_free(page);
+		__free_page(page);
+	}
+
+	return free;
+}
+
+/**
+ * minimum_image_size - Estimate the minimum acceptable size of an image.
+ * @saveable: Number of saveable pages in the system.
+ *
+ * We want to avoid attempting to free too much memory too hard, so estimate the
+ * minimum acceptable size of a hibernation image to use as the lower limit for
+ * preallocating memory.
+ *
+ * We assume that the minimum image size should be proportional to
+ *
+ * [number of saveable pages] - [number of pages that can be freed in theory]
+ *
+ * where the second term is the sum of (1) reclaimable slab pages, (2) active
+ * and (3) inactive anonymous pages, (4) active and (5) inactive file pages.
+ */
+static unsigned long minimum_image_size(unsigned long saveable)
+{
+	unsigned long size;
+
+	size = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B)
+		+ global_node_page_state(NR_ACTIVE_ANON)
+		+ global_node_page_state(NR_INACTIVE_ANON)
+		+ global_node_page_state(NR_ACTIVE_FILE)
+		+ global_node_page_state(NR_INACTIVE_FILE);
+
+	return saveable <= size ? 0 : saveable - size;
+}
+
+/**
+ * hibernate_preallocate_memory - Preallocate memory for hibernation image.
+ *
+ * To create a hibernation image it is necessary to make a copy of every page
+ * frame in use.  We also need a number of page frames to be free during
+ * hibernation for allocations made while saving the image and for device
+ * drivers, in case they need to allocate memory from their hibernation
+ * callbacks (these two numbers are given by PAGES_FOR_IO (which is a rough
+ * estimate) and reserved_size divided by PAGE_SIZE (which is tunable through
+ * /sys/power/reserved_size, respectively).  To make this happen, we compute the
+ * total number of available page frames and allocate at least
+ *
+ * ([page frames total] - PAGES_FOR_IO - [metadata pages]) / 2
+ *  - 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE)
+ *
+ * of them, which corresponds to the maximum size of a hibernation image.
+ *
+ * If image_size is set below the number following from the above formula,
+ * the preallocation of memory is continued until the total number of saveable
+ * pages in the system is below the requested image size or the minimum
+ * acceptable image size returned by minimum_image_size(), whichever is greater.
+ */
+int hibernate_preallocate_memory(void)
+{
+	struct zone *zone;
+	unsigned long saveable, size, max_size, count, highmem, pages = 0;
+	unsigned long alloc, save_highmem, pages_highmem, avail_normal;
+	ktime_t start, stop;
+	int error;
+
+	pr_info("Preallocating image memory\n");
+	start = ktime_get();
+
+	error = memory_bm_create(&orig_bm, GFP_IMAGE, PG_ANY);
+	if (error) {
+		pr_err("Cannot allocate original bitmap\n");
+		goto err_out;
+	}
+
+	error = memory_bm_create(&copy_bm, GFP_IMAGE, PG_ANY);
+	if (error) {
+		pr_err("Cannot allocate copy bitmap\n");
+		goto err_out;
+	}
+
+	alloc_normal = 0;
+	alloc_highmem = 0;
+
+	/* Count the number of saveable data pages. */
+	save_highmem = count_highmem_pages();
+	saveable = count_data_pages();
+
+	/*
+	 * Compute the total number of page frames we can use (count) and the
+	 * number of pages needed for image metadata (size).
+	 */
+	count = saveable;
+	saveable += save_highmem;
+	highmem = save_highmem;
+	size = 0;
+	for_each_populated_zone(zone) {
+		size += snapshot_additional_pages(zone);
+		if (is_highmem(zone))
+			highmem += zone_page_state(zone, NR_FREE_PAGES);
+		else
+			count += zone_page_state(zone, NR_FREE_PAGES);
+	}
+	avail_normal = count;
+	count += highmem;
+	count -= totalreserve_pages;
+
+	/* Compute the maximum number of saveable pages to leave in memory. */
+	max_size = (count - (size + PAGES_FOR_IO)) / 2
+			- 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE);
+	/* Compute the desired number of image pages specified by image_size. */
+	size = DIV_ROUND_UP(image_size, PAGE_SIZE);
+	if (size > max_size)
+		size = max_size;
+	/*
+	 * If the desired number of image pages is at least as large as the
+	 * current number of saveable pages in memory, allocate page frames for
+	 * the image and we're done.
+	 */
+	if (size >= saveable) {
+		pages = preallocate_image_highmem(save_highmem);
+		pages += preallocate_image_memory(saveable - pages, avail_normal);
+		goto out;
+	}
+
+	/* Estimate the minimum size of the image. */
+	pages = minimum_image_size(saveable);
+	/*
+	 * To avoid excessive pressure on the normal zone, leave room in it to
+	 * accommodate an image of the minimum size (unless it's already too
+	 * small, in which case don't preallocate pages from it at all).
+	 */
+	if (avail_normal > pages)
+		avail_normal -= pages;
+	else
+		avail_normal = 0;
+	if (size < pages)
+		size = min_t(unsigned long, pages, max_size);
+
+	/*
+	 * Let the memory management subsystem know that we're going to need a
+	 * large number of page frames to allocate and make it free some memory.
+	 * NOTE: If this is not done, performance will be hurt badly in some
+	 * test cases.
+	 */
+	shrink_all_memory(saveable - size);
+
+	/*
+	 * The number of saveable pages in memory was too high, so apply some
+	 * pressure to decrease it.  First, make room for the largest possible
+	 * image and fail if that doesn't work.  Next, try to decrease the size
+	 * of the image as much as indicated by 'size' using allocations from
+	 * highmem and non-highmem zones separately.
+	 */
+	pages_highmem = preallocate_image_highmem(highmem / 2);
+	alloc = count - max_size;
+	if (alloc > pages_highmem)
+		alloc -= pages_highmem;
+	else
+		alloc = 0;
+	pages = preallocate_image_memory(alloc, avail_normal);
+	if (pages < alloc) {
+		/* We have exhausted non-highmem pages, try highmem. */
+		alloc -= pages;
+		pages += pages_highmem;
+		pages_highmem = preallocate_image_highmem(alloc);
+		if (pages_highmem < alloc) {
+			pr_err("Image allocation is %lu pages short\n",
+				alloc - pages_highmem);
+			goto err_out;
+		}
+		pages += pages_highmem;
+		/*
+		 * size is the desired number of saveable pages to leave in
+		 * memory, so try to preallocate (all memory - size) pages.
+		 */
+		alloc = (count - pages) - size;
+		pages += preallocate_image_highmem(alloc);
+	} else {
+		/*
+		 * There are approximately max_size saveable pages at this point
+		 * and we want to reduce this number down to size.
+		 */
+		alloc = max_size - size;
+		size = preallocate_highmem_fraction(alloc, highmem, count);
+		pages_highmem += size;
+		alloc -= size;
+		size = preallocate_image_memory(alloc, avail_normal);
+		pages_highmem += preallocate_image_highmem(alloc - size);
+		pages += pages_highmem + size;
+	}
+
+	/*
+	 * We only need as many page frames for the image as there are saveable
+	 * pages in memory, but we have allocated more.  Release the excessive
+	 * ones now.
+	 */
+	pages -= free_unnecessary_pages();
+
+ out:
+	stop = ktime_get();
+	pr_info("Allocated %lu pages for snapshot\n", pages);
+	swsusp_show_speed(start, stop, pages, "Allocated");
+
+	return 0;
+
+ err_out:
+	swsusp_free();
+	return -ENOMEM;
+}
+
+#ifdef CONFIG_HIGHMEM
+/**
+ * count_pages_for_highmem - Count non-highmem pages needed for copying highmem.
+ *
+ * Compute the number of non-highmem pages that will be necessary for creating
+ * copies of highmem pages.
+ */
+static unsigned int count_pages_for_highmem(unsigned int nr_highmem)
+{
+	unsigned int free_highmem = count_free_highmem_pages() + alloc_highmem;
+
+	if (free_highmem >= nr_highmem)
+		nr_highmem = 0;
+	else
+		nr_highmem -= free_highmem;
+
+	return nr_highmem;
+}
+#else
+static unsigned int count_pages_for_highmem(unsigned int nr_highmem) { return 0; }
+#endif /* CONFIG_HIGHMEM */
+
+/**
+ * enough_free_mem - Check if there is enough free memory for the image.
+ */
+static int enough_free_mem(unsigned int nr_pages, unsigned int nr_highmem)
+{
+	struct zone *zone;
+	unsigned int free = alloc_normal;
+
+	for_each_populated_zone(zone)
+		if (!is_highmem(zone))
+			free += zone_page_state(zone, NR_FREE_PAGES);
+
+	nr_pages += count_pages_for_highmem(nr_highmem);
+	pr_debug("Normal pages needed: %u + %u, available pages: %u\n",
+		 nr_pages, PAGES_FOR_IO, free);
+
+	return free > nr_pages + PAGES_FOR_IO;
+}
+
+#ifdef CONFIG_HIGHMEM
+/**
+ * get_highmem_buffer - Allocate a buffer for highmem pages.
+ *
+ * If there are some highmem pages in the hibernation image, we may need a
+ * buffer to copy them and/or load their data.
+ */
+static inline int get_highmem_buffer(int safe_needed)
+{
+	buffer = get_image_page(GFP_ATOMIC, safe_needed);
+	return buffer ? 0 : -ENOMEM;
+}
+
+/**
+ * alloc_highmem_pages - Allocate some highmem pages for the image.
+ *
+ * Try to allocate as many pages as needed, but if the number of free highmem
+ * pages is less than that, allocate them all.
+ */
+static inline unsigned int alloc_highmem_pages(struct memory_bitmap *bm,
+					       unsigned int nr_highmem)
+{
+	unsigned int to_alloc = count_free_highmem_pages();
+
+	if (to_alloc > nr_highmem)
+		to_alloc = nr_highmem;
+
+	nr_highmem -= to_alloc;
+	while (to_alloc-- > 0) {
+		struct page *page;
+
+		page = alloc_image_page(__GFP_HIGHMEM|__GFP_KSWAPD_RECLAIM);
+		memory_bm_set_bit(bm, page_to_pfn(page));
+	}
+	return nr_highmem;
+}
+#else
+static inline int get_highmem_buffer(int safe_needed) { return 0; }
+
+static inline unsigned int alloc_highmem_pages(struct memory_bitmap *bm,
+					       unsigned int n) { return 0; }
+#endif /* CONFIG_HIGHMEM */
+
+/**
+ * swsusp_alloc - Allocate memory for hibernation image.
+ *
+ * We first try to allocate as many highmem pages as there are
+ * saveable highmem pages in the system.  If that fails, we allocate
+ * non-highmem pages for the copies of the remaining highmem ones.
+ *
+ * In this approach it is likely that the copies of highmem pages will
+ * also be located in the high memory, because of the way in which
+ * copy_data_pages() works.
+ */
+static int swsusp_alloc(struct memory_bitmap *copy_bm,
+			unsigned int nr_pages, unsigned int nr_highmem)
+{
+	if (nr_highmem > 0) {
+		if (get_highmem_buffer(PG_ANY))
+			goto err_out;
+		if (nr_highmem > alloc_highmem) {
+			nr_highmem -= alloc_highmem;
+			nr_pages += alloc_highmem_pages(copy_bm, nr_highmem);
+		}
+	}
+	if (nr_pages > alloc_normal) {
+		nr_pages -= alloc_normal;
+		while (nr_pages-- > 0) {
+			struct page *page;
+
+			page = alloc_image_page(GFP_ATOMIC);
+			if (!page)
+				goto err_out;
+			memory_bm_set_bit(copy_bm, page_to_pfn(page));
+		}
+	}
+
+	return 0;
+
+ err_out:
+	swsusp_free();
+	return -ENOMEM;
+}
+
+asmlinkage __visible int swsusp_save(void)
+{
+	unsigned int nr_pages, nr_highmem;
+
+	pr_info("Creating image:\n");
+
+	drain_local_pages(NULL);
+	nr_pages = count_data_pages();
+	nr_highmem = count_highmem_pages();
+	pr_info("Need to copy %u pages\n", nr_pages + nr_highmem);
+
+	if (!enough_free_mem(nr_pages, nr_highmem)) {
+		pr_err("Not enough free memory\n");
+		return -ENOMEM;
+	}
+
+	if (swsusp_alloc(&copy_bm, nr_pages, nr_highmem)) {
+		pr_err("Memory allocation failed\n");
+		return -ENOMEM;
+	}
+
+	/*
+	 * During allocating of suspend pagedir, new cold pages may appear.
+	 * Kill them.
+	 */
+	drain_local_pages(NULL);
+	copy_data_pages(&copy_bm, &orig_bm);
+
+	/*
+	 * End of critical section. From now on, we can write to memory,
+	 * but we should not touch disk. This specially means we must _not_
+	 * touch swap space! Except we must write out our image of course.
+	 */
+
+	nr_pages += nr_highmem;
+	nr_copy_pages = nr_pages;
+	nr_meta_pages = DIV_ROUND_UP(nr_pages * sizeof(long), PAGE_SIZE);
+
+	pr_info("Image created (%d pages copied)\n", nr_pages);
+
+	return 0;
+}
+
+#ifndef CONFIG_ARCH_HIBERNATION_HEADER
+static int init_header_complete(struct swsusp_info *info)
+{
+	memcpy(&info->uts, init_utsname(), sizeof(struct new_utsname));
+	info->version_code = LINUX_VERSION_CODE;
+	return 0;
+}
+
+static const char *check_image_kernel(struct swsusp_info *info)
+{
+	if (info->version_code != LINUX_VERSION_CODE)
+		return "kernel version";
+	if (strcmp(info->uts.sysname,init_utsname()->sysname))
+		return "system type";
+	if (strcmp(info->uts.release,init_utsname()->release))
+		return "kernel release";
+	if (strcmp(info->uts.version,init_utsname()->version))
+		return "version";
+	if (strcmp(info->uts.machine,init_utsname()->machine))
+		return "machine";
+	return NULL;
+}
+#endif /* CONFIG_ARCH_HIBERNATION_HEADER */
+
+unsigned long snapshot_get_image_size(void)
+{
+	return nr_copy_pages + nr_meta_pages + 1;
+}
+
+static int init_header(struct swsusp_info *info)
+{
+	memset(info, 0, sizeof(struct swsusp_info));
+	info->num_physpages = get_num_physpages();
+	info->image_pages = nr_copy_pages;
+	info->pages = snapshot_get_image_size();
+	info->size = info->pages;
+	info->size <<= PAGE_SHIFT;
+	return init_header_complete(info);
+}
+
+/**
+ * pack_pfns - Prepare PFNs for saving.
+ * @bm: Memory bitmap.
+ * @buf: Memory buffer to store the PFNs in.
+ *
+ * PFNs corresponding to set bits in @bm are stored in the area of memory
+ * pointed to by @buf (1 page at a time).
+ */
+static inline void pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
+{
+	int j;
+
+	for (j = 0; j < PAGE_SIZE / sizeof(long); j++) {
+		buf[j] = memory_bm_next_pfn(bm);
+		if (unlikely(buf[j] == BM_END_OF_MAP))
+			break;
+	}
+}
+
+/**
+ * snapshot_read_next - Get the address to read the next image page from.
+ * @handle: Snapshot handle to be used for the reading.
+ *
+ * On the first call, @handle should point to a zeroed snapshot_handle
+ * structure.  The structure gets populated then and a pointer to it should be
+ * passed to this function every next time.
+ *
+ * On success, the function returns a positive number.  Then, the caller
+ * is allowed to read up to the returned number of bytes from the memory
+ * location computed by the data_of() macro.
+ *
+ * The function returns 0 to indicate the end of the data stream condition,
+ * and negative numbers are returned on errors.  If that happens, the structure
+ * pointed to by @handle is not updated and should not be used any more.
+ */
+int snapshot_read_next(struct snapshot_handle *handle)
+{
+	if (handle->cur > nr_meta_pages + nr_copy_pages)
+		return 0;
+
+	if (!buffer) {
+		/* This makes the buffer be freed by swsusp_free() */
+		buffer = get_image_page(GFP_ATOMIC, PG_ANY);
+		if (!buffer)
+			return -ENOMEM;
+	}
+	if (!handle->cur) {
+		int error;
+
+		error = init_header((struct swsusp_info *)buffer);
+		if (error)
+			return error;
+		handle->buffer = buffer;
+		memory_bm_position_reset(&orig_bm);
+		memory_bm_position_reset(&copy_bm);
+	} else if (handle->cur <= nr_meta_pages) {
+		clear_page(buffer);
+		pack_pfns(buffer, &orig_bm);
+	} else {
+		struct page *page;
+
+		page = pfn_to_page(memory_bm_next_pfn(&copy_bm));
+		if (PageHighMem(page)) {
+			/*
+			 * Highmem pages are copied to the buffer,
+			 * because we can't return with a kmapped
+			 * highmem page (we may not be called again).
+			 */
+			void *kaddr;
+
+			kaddr = kmap_atomic(page);
+			copy_page(buffer, kaddr);
+			kunmap_atomic(kaddr);
+			handle->buffer = buffer;
+		} else {
+			handle->buffer = page_address(page);
+		}
+	}
+	handle->cur++;
+	return PAGE_SIZE;
+}
+
+static void duplicate_memory_bitmap(struct memory_bitmap *dst,
+				    struct memory_bitmap *src)
+{
+	unsigned long pfn;
+
+	memory_bm_position_reset(src);
+	pfn = memory_bm_next_pfn(src);
+	while (pfn != BM_END_OF_MAP) {
+		memory_bm_set_bit(dst, pfn);
+		pfn = memory_bm_next_pfn(src);
+	}
+}
+
+/**
+ * mark_unsafe_pages - Mark pages that were used before hibernation.
+ *
+ * Mark the pages that cannot be used for storing the image during restoration,
+ * because they conflict with the pages that had been used before hibernation.
+ */
+static void mark_unsafe_pages(struct memory_bitmap *bm)
+{
+	unsigned long pfn;
+
+	/* Clear the "free"/"unsafe" bit for all PFNs */
+	memory_bm_position_reset(free_pages_map);
+	pfn = memory_bm_next_pfn(free_pages_map);
+	while (pfn != BM_END_OF_MAP) {
+		memory_bm_clear_current(free_pages_map);
+		pfn = memory_bm_next_pfn(free_pages_map);
+	}
+
+	/* Mark pages that correspond to the "original" PFNs as "unsafe" */
+	duplicate_memory_bitmap(free_pages_map, bm);
+
+	allocated_unsafe_pages = 0;
+}
+
+static int check_header(struct swsusp_info *info)
+{
+	const char *reason;
+
+	reason = check_image_kernel(info);
+	if (!reason && info->num_physpages != get_num_physpages())
+		reason = "memory size";
+	if (reason) {
+		pr_err("Image mismatch: %s\n", reason);
+		return -EPERM;
+	}
+	return 0;
+}
+
+/**
+ * load_header - Check the image header and copy the data from it.
+ */
+static int load_header(struct swsusp_info *info)
+{
+	int error;
+
+	restore_pblist = NULL;
+	error = check_header(info);
+	if (!error) {
+		nr_copy_pages = info->image_pages;
+		nr_meta_pages = info->pages - info->image_pages - 1;
+	}
+	return error;
+}
+
+/**
+ * unpack_orig_pfns - Set bits corresponding to given PFNs in a memory bitmap.
+ * @bm: Memory bitmap.
+ * @buf: Area of memory containing the PFNs.
+ *
+ * For each element of the array pointed to by @buf (1 page at a time), set the
+ * corresponding bit in @bm.
+ */
+static int unpack_orig_pfns(unsigned long *buf, struct memory_bitmap *bm)
+{
+	int j;
+
+	for (j = 0; j < PAGE_SIZE / sizeof(long); j++) {
+		if (unlikely(buf[j] == BM_END_OF_MAP))
+			break;
+
+		if (pfn_valid(buf[j]) && memory_bm_pfn_present(bm, buf[j]))
+			memory_bm_set_bit(bm, buf[j]);
+		else
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_HIGHMEM
+/*
+ * struct highmem_pbe is used for creating the list of highmem pages that
+ * should be restored atomically during the resume from disk, because the page
+ * frames they have occupied before the suspend are in use.
+ */
+struct highmem_pbe {
+	struct page *copy_page;	/* data is here now */
+	struct page *orig_page;	/* data was here before the suspend */
+	struct highmem_pbe *next;
+};
+
+/*
+ * List of highmem PBEs needed for restoring the highmem pages that were
+ * allocated before the suspend and included in the suspend image, but have
+ * also been allocated by the "resume" kernel, so their contents cannot be
+ * written directly to their "original" page frames.
+ */
+static struct highmem_pbe *highmem_pblist;
+
+/**
+ * count_highmem_image_pages - Compute the number of highmem pages in the image.
+ * @bm: Memory bitmap.
+ *
+ * The bits in @bm that correspond to image pages are assumed to be set.
+ */
+static unsigned int count_highmem_image_pages(struct memory_bitmap *bm)
+{
+	unsigned long pfn;
+	unsigned int cnt = 0;
+
+	memory_bm_position_reset(bm);
+	pfn = memory_bm_next_pfn(bm);
+	while (pfn != BM_END_OF_MAP) {
+		if (PageHighMem(pfn_to_page(pfn)))
+			cnt++;
+
+		pfn = memory_bm_next_pfn(bm);
+	}
+	return cnt;
+}
+
+static unsigned int safe_highmem_pages;
+
+static struct memory_bitmap *safe_highmem_bm;
+
+/**
+ * prepare_highmem_image - Allocate memory for loading highmem data from image.
+ * @bm: Pointer to an uninitialized memory bitmap structure.
+ * @nr_highmem_p: Pointer to the number of highmem image pages.
+ *
+ * Try to allocate as many highmem pages as there are highmem image pages
+ * (@nr_highmem_p points to the variable containing the number of highmem image
+ * pages).  The pages that are "safe" (ie. will not be overwritten when the
+ * hibernation image is restored entirely) have the corresponding bits set in
+ * @bm (it must be uninitialized).
+ *
+ * NOTE: This function should not be called if there are no highmem image pages.
+ */
+static int prepare_highmem_image(struct memory_bitmap *bm,
+				 unsigned int *nr_highmem_p)
+{
+	unsigned int to_alloc;
+
+	if (memory_bm_create(bm, GFP_ATOMIC, PG_SAFE))
+		return -ENOMEM;
+
+	if (get_highmem_buffer(PG_SAFE))
+		return -ENOMEM;
+
+	to_alloc = count_free_highmem_pages();
+	if (to_alloc > *nr_highmem_p)
+		to_alloc = *nr_highmem_p;
+	else
+		*nr_highmem_p = to_alloc;
+
+	safe_highmem_pages = 0;
+	while (to_alloc-- > 0) {
+		struct page *page;
+
+		page = alloc_page(__GFP_HIGHMEM);
+		if (!swsusp_page_is_free(page)) {
+			/* The page is "safe", set its bit the bitmap */
+			memory_bm_set_bit(bm, page_to_pfn(page));
+			safe_highmem_pages++;
+		}
+		/* Mark the page as allocated */
+		swsusp_set_page_forbidden(page);
+		swsusp_set_page_free(page);
+	}
+	memory_bm_position_reset(bm);
+	safe_highmem_bm = bm;
+	return 0;
+}
+
+static struct page *last_highmem_page;
+
+/**
+ * get_highmem_page_buffer - Prepare a buffer to store a highmem image page.
+ *
+ * For a given highmem image page get a buffer that suspend_write_next() should
+ * return to its caller to write to.
+ *
+ * If the page is to be saved to its "original" page frame or a copy of
+ * the page is to be made in the highmem, @buffer is returned.  Otherwise,
+ * the copy of the page is to be made in normal memory, so the address of
+ * the copy is returned.
+ *
+ * If @buffer is returned, the caller of suspend_write_next() will write
+ * the page's contents to @buffer, so they will have to be copied to the
+ * right location on the next call to suspend_write_next() and it is done
+ * with the help of copy_last_highmem_page().  For this purpose, if
+ * @buffer is returned, @last_highmem_page is set to the page to which
+ * the data will have to be copied from @buffer.
+ */
+static void *get_highmem_page_buffer(struct page *page,
+				     struct chain_allocator *ca)
+{
+	struct highmem_pbe *pbe;
+	void *kaddr;
+
+	if (swsusp_page_is_forbidden(page) && swsusp_page_is_free(page)) {
+		/*
+		 * We have allocated the "original" page frame and we can
+		 * use it directly to store the loaded page.
+		 */
+		last_highmem_page = page;
+		return buffer;
+	}
+	/*
+	 * The "original" page frame has not been allocated and we have to
+	 * use a "safe" page frame to store the loaded page.
+	 */
+	pbe = chain_alloc(ca, sizeof(struct highmem_pbe));
+	if (!pbe) {
+		swsusp_free();
+		return ERR_PTR(-ENOMEM);
+	}
+	pbe->orig_page = page;
+	if (safe_highmem_pages > 0) {
+		struct page *tmp;
+
+		/* Copy of the page will be stored in high memory */
+		kaddr = buffer;
+		tmp = pfn_to_page(memory_bm_next_pfn(safe_highmem_bm));
+		safe_highmem_pages--;
+		last_highmem_page = tmp;
+		pbe->copy_page = tmp;
+	} else {
+		/* Copy of the page will be stored in normal memory */
+		kaddr = __get_safe_page(ca->gfp_mask);
+		if (!kaddr)
+			return ERR_PTR(-ENOMEM);
+		pbe->copy_page = virt_to_page(kaddr);
+	}
+	pbe->next = highmem_pblist;
+	highmem_pblist = pbe;
+	return kaddr;
+}
+
+/**
+ * copy_last_highmem_page - Copy most the most recent highmem image page.
+ *
+ * Copy the contents of a highmem image from @buffer, where the caller of
+ * snapshot_write_next() has stored them, to the right location represented by
+ * @last_highmem_page .
+ */
+static void copy_last_highmem_page(void)
+{
+	if (last_highmem_page) {
+		void *dst;
+
+		dst = kmap_atomic(last_highmem_page);
+		copy_page(dst, buffer);
+		kunmap_atomic(dst);
+		last_highmem_page = NULL;
+	}
+}
+
+static inline int last_highmem_page_copied(void)
+{
+	return !last_highmem_page;
+}
+
+static inline void free_highmem_data(void)
+{
+	if (safe_highmem_bm)
+		memory_bm_free(safe_highmem_bm, PG_UNSAFE_CLEAR);
+
+	if (buffer)
+		free_image_page(buffer, PG_UNSAFE_CLEAR);
+}
+#else
+static unsigned int count_highmem_image_pages(struct memory_bitmap *bm) { return 0; }
+
+static inline int prepare_highmem_image(struct memory_bitmap *bm,
+					unsigned int *nr_highmem_p) { return 0; }
+
+static inline void *get_highmem_page_buffer(struct page *page,
+					    struct chain_allocator *ca)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline void copy_last_highmem_page(void) {}
+static inline int last_highmem_page_copied(void) { return 1; }
+static inline void free_highmem_data(void) {}
+#endif /* CONFIG_HIGHMEM */
+
+#define PBES_PER_LINKED_PAGE	(LINKED_PAGE_DATA_SIZE / sizeof(struct pbe))
+
+/**
+ * prepare_image - Make room for loading hibernation image.
+ * @new_bm: Uninitialized memory bitmap structure.
+ * @bm: Memory bitmap with unsafe pages marked.
+ *
+ * Use @bm to mark the pages that will be overwritten in the process of
+ * restoring the system memory state from the suspend image ("unsafe" pages)
+ * and allocate memory for the image.
+ *
+ * The idea is to allocate a new memory bitmap first and then allocate
+ * as many pages as needed for image data, but without specifying what those
+ * pages will be used for just yet.  Instead, we mark them all as allocated and
+ * create a lists of "safe" pages to be used later.  On systems with high
+ * memory a list of "safe" highmem pages is created too.
+ */
+static int prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
+{
+	unsigned int nr_pages, nr_highmem;
+	struct linked_page *lp;
+	int error;
+
+	/* If there is no highmem, the buffer will not be necessary */
+	free_image_page(buffer, PG_UNSAFE_CLEAR);
+	buffer = NULL;
+
+	nr_highmem = count_highmem_image_pages(bm);
+	mark_unsafe_pages(bm);
+
+	error = memory_bm_create(new_bm, GFP_ATOMIC, PG_SAFE);
+	if (error)
+		goto Free;
+
+	duplicate_memory_bitmap(new_bm, bm);
+	memory_bm_free(bm, PG_UNSAFE_KEEP);
+	if (nr_highmem > 0) {
+		error = prepare_highmem_image(bm, &nr_highmem);
+		if (error)
+			goto Free;
+	}
+	/*
+	 * Reserve some safe pages for potential later use.
+	 *
+	 * NOTE: This way we make sure there will be enough safe pages for the
+	 * chain_alloc() in get_buffer().  It is a bit wasteful, but
+	 * nr_copy_pages cannot be greater than 50% of the memory anyway.
+	 *
+	 * nr_copy_pages cannot be less than allocated_unsafe_pages too.
+	 */
+	nr_pages = nr_copy_pages - nr_highmem - allocated_unsafe_pages;
+	nr_pages = DIV_ROUND_UP(nr_pages, PBES_PER_LINKED_PAGE);
+	while (nr_pages > 0) {
+		lp = get_image_page(GFP_ATOMIC, PG_SAFE);
+		if (!lp) {
+			error = -ENOMEM;
+			goto Free;
+		}
+		lp->next = safe_pages_list;
+		safe_pages_list = lp;
+		nr_pages--;
+	}
+	/* Preallocate memory for the image */
+	nr_pages = nr_copy_pages - nr_highmem - allocated_unsafe_pages;
+	while (nr_pages > 0) {
+		lp = (struct linked_page *)get_zeroed_page(GFP_ATOMIC);
+		if (!lp) {
+			error = -ENOMEM;
+			goto Free;
+		}
+		if (!swsusp_page_is_free(virt_to_page(lp))) {
+			/* The page is "safe", add it to the list */
+			lp->next = safe_pages_list;
+			safe_pages_list = lp;
+		}
+		/* Mark the page as allocated */
+		swsusp_set_page_forbidden(virt_to_page(lp));
+		swsusp_set_page_free(virt_to_page(lp));
+		nr_pages--;
+	}
+	return 0;
+
+ Free:
+	swsusp_free();
+	return error;
+}
+
+/**
+ * get_buffer - Get the address to store the next image data page.
+ *
+ * Get the address that snapshot_write_next() should return to its caller to
+ * write to.
+ */
+static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
+{
+	struct pbe *pbe;
+	struct page *page;
+	unsigned long pfn = memory_bm_next_pfn(bm);
+
+	if (pfn == BM_END_OF_MAP)
+		return ERR_PTR(-EFAULT);
+
+	page = pfn_to_page(pfn);
+	if (PageHighMem(page))
+		return get_highmem_page_buffer(page, ca);
+
+	if (swsusp_page_is_forbidden(page) && swsusp_page_is_free(page))
+		/*
+		 * We have allocated the "original" page frame and we can
+		 * use it directly to store the loaded page.
+		 */
+		return page_address(page);
+
+	/*
+	 * The "original" page frame has not been allocated and we have to
+	 * use a "safe" page frame to store the loaded page.
+	 */
+	pbe = chain_alloc(ca, sizeof(struct pbe));
+	if (!pbe) {
+		swsusp_free();
+		return ERR_PTR(-ENOMEM);
+	}
+	pbe->orig_address = page_address(page);
+	pbe->address = __get_safe_page(ca->gfp_mask);
+	if (!pbe->address)
+		return ERR_PTR(-ENOMEM);
+	pbe->next = restore_pblist;
+	restore_pblist = pbe;
+	return pbe->address;
+}
+
+/**
+ * snapshot_write_next - Get the address to store the next image page.
+ * @handle: Snapshot handle structure to guide the writing.
+ *
+ * On the first call, @handle should point to a zeroed snapshot_handle
+ * structure.  The structure gets populated then and a pointer to it should be
+ * passed to this function every next time.
+ *
+ * On success, the function returns a positive number.  Then, the caller
+ * is allowed to write up to the returned number of bytes to the memory
+ * location computed by the data_of() macro.
+ *
+ * The function returns 0 to indicate the "end of file" condition.  Negative
+ * numbers are returned on errors, in which cases the structure pointed to by
+ * @handle is not updated and should not be used any more.
+ */
+int snapshot_write_next(struct snapshot_handle *handle)
+{
+	static struct chain_allocator ca;
+	int error = 0;
+
+	/* Check if we have already loaded the entire image */
+	if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages)
+		return 0;
+
+	if (!handle->cur) {
+		if (!buffer)
+			/* This makes the buffer be freed by swsusp_free() */
+			buffer = get_image_page(GFP_ATOMIC, PG_ANY);
+
+		if (!buffer)
+			return -ENOMEM;
+
+		handle->buffer = buffer;
+	} else if (handle->cur == 1) {
+		error = load_header(buffer);
+		if (error)
+			return error;
+
+		safe_pages_list = NULL;
+
+		error = memory_bm_create(&copy_bm, GFP_ATOMIC, PG_ANY);
+		if (error)
+			return error;
+
+		hibernate_restore_protection_begin();
+	} else if (handle->cur <= nr_meta_pages + 1) {
+		error = unpack_orig_pfns(buffer, &copy_bm);
+		if (error)
+			return error;
+
+		if (handle->cur == nr_meta_pages + 1) {
+			error = prepare_image(&orig_bm, &copy_bm);
+			if (error)
+				return error;
+
+			chain_init(&ca, GFP_ATOMIC, PG_SAFE);
+			memory_bm_position_reset(&orig_bm);
+			restore_pblist = NULL;
+			handle->buffer = get_buffer(&orig_bm, &ca);
+			if (IS_ERR(handle->buffer))
+				return PTR_ERR(handle->buffer);
+		}
+	} else {
+		copy_last_highmem_page();
+		hibernate_restore_protect_page(handle->buffer);
+		handle->buffer = get_buffer(&orig_bm, &ca);
+		if (IS_ERR(handle->buffer))
+			return PTR_ERR(handle->buffer);
+	}
+	handle->sync_read = (handle->buffer == buffer);
+	handle->cur++;
+	return PAGE_SIZE;
+}
+
+/**
+ * snapshot_write_finalize - Complete the loading of a hibernation image.
+ *
+ * Must be called after the last call to snapshot_write_next() in case the last
+ * page in the image happens to be a highmem page and its contents should be
+ * stored in highmem.  Additionally, it recycles bitmap memory that's not
+ * necessary any more.
+ */
+void snapshot_write_finalize(struct snapshot_handle *handle)
+{
+	copy_last_highmem_page();
+	hibernate_restore_protect_page(handle->buffer);
+	/* Do that only if we have loaded the image entirely */
+	if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages) {
+		memory_bm_recycle(&orig_bm);
+		free_highmem_data();
+	}
+}
+
+int snapshot_image_loaded(struct snapshot_handle *handle)
+{
+	return !(!nr_copy_pages || !last_highmem_page_copied() ||
+			handle->cur <= nr_meta_pages + nr_copy_pages);
+}
+
+#ifdef CONFIG_HIGHMEM
+/* Assumes that @buf is ready and points to a "safe" page */
+static inline void swap_two_pages_data(struct page *p1, struct page *p2,
+				       void *buf)
+{
+	void *kaddr1, *kaddr2;
+
+	kaddr1 = kmap_atomic(p1);
+	kaddr2 = kmap_atomic(p2);
+	copy_page(buf, kaddr1);
+	copy_page(kaddr1, kaddr2);
+	copy_page(kaddr2, buf);
+	kunmap_atomic(kaddr2);
+	kunmap_atomic(kaddr1);
+}
+
+/**
+ * restore_highmem - Put highmem image pages into their original locations.
+ *
+ * For each highmem page that was in use before hibernation and is included in
+ * the image, and also has been allocated by the "restore" kernel, swap its
+ * current contents with the previous (ie. "before hibernation") ones.
+ *
+ * If the restore eventually fails, we can call this function once again and
+ * restore the highmem state as seen by the restore kernel.
+ */
+int restore_highmem(void)
+{
+	struct highmem_pbe *pbe = highmem_pblist;
+	void *buf;
+
+	if (!pbe)
+		return 0;
+
+	buf = get_image_page(GFP_ATOMIC, PG_SAFE);
+	if (!buf)
+		return -ENOMEM;
+
+	while (pbe) {
+		swap_two_pages_data(pbe->copy_page, pbe->orig_page, buf);
+		pbe = pbe->next;
+	}
+	free_image_page(buf, PG_UNSAFE_CLEAR);
+	return 0;
+}
+#endif /* CONFIG_HIGHMEM */