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Linux/kernel/power/snapshot.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * linux/kernel/power/snapshot.c
  4  *
  5  * This file provides system snapshot/restore functionality for swsusp.
  6  *
  7  * Copyright (C) 1998-2005 Pavel Machek <pavel@ucw.cz>
  8  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
  9  */
 10 
 11 #define pr_fmt(fmt) "PM: hibernation: " fmt
 12 
 13 #include <linux/version.h>
 14 #include <linux/module.h>
 15 #include <linux/mm.h>
 16 #include <linux/suspend.h>
 17 #include <linux/delay.h>
 18 #include <linux/bitops.h>
 19 #include <linux/spinlock.h>
 20 #include <linux/kernel.h>
 21 #include <linux/pm.h>
 22 #include <linux/device.h>
 23 #include <linux/init.h>
 24 #include <linux/memblock.h>
 25 #include <linux/nmi.h>
 26 #include <linux/syscalls.h>
 27 #include <linux/console.h>
 28 #include <linux/highmem.h>
 29 #include <linux/list.h>
 30 #include <linux/slab.h>
 31 #include <linux/compiler.h>
 32 #include <linux/ktime.h>
 33 #include <linux/set_memory.h>
 34 
 35 #include <linux/uaccess.h>
 36 #include <asm/mmu_context.h>
 37 #include <asm/tlbflush.h>
 38 #include <asm/io.h>
 39 
 40 #include "power.h"
 41 
 42 #if defined(CONFIG_STRICT_KERNEL_RWX) && defined(CONFIG_ARCH_HAS_SET_MEMORY)
 43 static bool hibernate_restore_protection;
 44 static bool hibernate_restore_protection_active;
 45 
 46 void enable_restore_image_protection(void)
 47 {
 48         hibernate_restore_protection = true;
 49 }
 50 
 51 static inline void hibernate_restore_protection_begin(void)
 52 {
 53         hibernate_restore_protection_active = hibernate_restore_protection;
 54 }
 55 
 56 static inline void hibernate_restore_protection_end(void)
 57 {
 58         hibernate_restore_protection_active = false;
 59 }
 60 
 61 static inline void hibernate_restore_protect_page(void *page_address)
 62 {
 63         if (hibernate_restore_protection_active)
 64                 set_memory_ro((unsigned long)page_address, 1);
 65 }
 66 
 67 static inline void hibernate_restore_unprotect_page(void *page_address)
 68 {
 69         if (hibernate_restore_protection_active)
 70                 set_memory_rw((unsigned long)page_address, 1);
 71 }
 72 #else
 73 static inline void hibernate_restore_protection_begin(void) {}
 74 static inline void hibernate_restore_protection_end(void) {}
 75 static inline void hibernate_restore_protect_page(void *page_address) {}
 76 static inline void hibernate_restore_unprotect_page(void *page_address) {}
 77 #endif /* CONFIG_STRICT_KERNEL_RWX  && CONFIG_ARCH_HAS_SET_MEMORY */
 78 
 79 
 80 /*
 81  * The calls to set_direct_map_*() should not fail because remapping a page
 82  * here means that we only update protection bits in an existing PTE.
 83  * It is still worth to have a warning here if something changes and this
 84  * will no longer be the case.
 85  */
 86 static inline void hibernate_map_page(struct page *page)
 87 {
 88         if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
 89                 int ret = set_direct_map_default_noflush(page);
 90 
 91                 if (ret)
 92                         pr_warn_once("Failed to remap page\n");
 93         } else {
 94                 debug_pagealloc_map_pages(page, 1);
 95         }
 96 }
 97 
 98 static inline void hibernate_unmap_page(struct page *page)
 99 {
100         if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
101                 unsigned long addr = (unsigned long)page_address(page);
102                 int ret  = set_direct_map_invalid_noflush(page);
103 
104                 if (ret)
105                         pr_warn_once("Failed to remap page\n");
106 
107                 flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
108         } else {
109                 debug_pagealloc_unmap_pages(page, 1);
110         }
111 }
112 
113 static int swsusp_page_is_free(struct page *);
114 static void swsusp_set_page_forbidden(struct page *);
115 static void swsusp_unset_page_forbidden(struct page *);
116 
117 /*
118  * Number of bytes to reserve for memory allocations made by device drivers
119  * from their ->freeze() and ->freeze_noirq() callbacks so that they don't
120  * cause image creation to fail (tunable via /sys/power/reserved_size).
121  */
122 unsigned long reserved_size;
123 
124 void __init hibernate_reserved_size_init(void)
125 {
126         reserved_size = SPARE_PAGES * PAGE_SIZE;
127 }
128 
129 /*
130  * Preferred image size in bytes (tunable via /sys/power/image_size).
131  * When it is set to N, swsusp will do its best to ensure the image
132  * size will not exceed N bytes, but if that is impossible, it will
133  * try to create the smallest image possible.
134  */
135 unsigned long image_size;
136 
137 void __init hibernate_image_size_init(void)
138 {
139         image_size = ((totalram_pages() * 2) / 5) * PAGE_SIZE;
140 }
141 
142 /*
143  * List of PBEs needed for restoring the pages that were allocated before
144  * the suspend and included in the suspend image, but have also been
145  * allocated by the "resume" kernel, so their contents cannot be written
146  * directly to their "original" page frames.
147  */
148 struct pbe *restore_pblist;
149 
150 /* struct linked_page is used to build chains of pages */
151 
152 #define LINKED_PAGE_DATA_SIZE   (PAGE_SIZE - sizeof(void *))
153 
154 struct linked_page {
155         struct linked_page *next;
156         char data[LINKED_PAGE_DATA_SIZE];
157 } __packed;
158 
159 /*
160  * List of "safe" pages (ie. pages that were not used by the image kernel
161  * before hibernation) that may be used as temporary storage for image kernel
162  * memory contents.
163  */
164 static struct linked_page *safe_pages_list;
165 
166 /* Pointer to an auxiliary buffer (1 page) */
167 static void *buffer;
168 
169 #define PG_ANY          0
170 #define PG_SAFE         1
171 #define PG_UNSAFE_CLEAR 1
172 #define PG_UNSAFE_KEEP  0
173 
174 static unsigned int allocated_unsafe_pages;
175 
176 /**
177  * get_image_page - Allocate a page for a hibernation image.
178  * @gfp_mask: GFP mask for the allocation.
179  * @safe_needed: Get pages that were not used before hibernation (restore only)
180  *
181  * During image restoration, for storing the PBE list and the image data, we can
182  * only use memory pages that do not conflict with the pages used before
183  * hibernation.  The "unsafe" pages have PageNosaveFree set and we count them
184  * using allocated_unsafe_pages.
185  *
186  * Each allocated image page is marked as PageNosave and PageNosaveFree so that
187  * swsusp_free() can release it.
188  */
189 static void *get_image_page(gfp_t gfp_mask, int safe_needed)
190 {
191         void *res;
192 
193         res = (void *)get_zeroed_page(gfp_mask);
194         if (safe_needed)
195                 while (res && swsusp_page_is_free(virt_to_page(res))) {
196                         /* The page is unsafe, mark it for swsusp_free() */
197                         swsusp_set_page_forbidden(virt_to_page(res));
198                         allocated_unsafe_pages++;
199                         res = (void *)get_zeroed_page(gfp_mask);
200                 }
201         if (res) {
202                 swsusp_set_page_forbidden(virt_to_page(res));
203                 swsusp_set_page_free(virt_to_page(res));
204         }
205         return res;
206 }
207 
208 static void *__get_safe_page(gfp_t gfp_mask)
209 {
210         if (safe_pages_list) {
211                 void *ret = safe_pages_list;
212 
213                 safe_pages_list = safe_pages_list->next;
214                 memset(ret, 0, PAGE_SIZE);
215                 return ret;
216         }
217         return get_image_page(gfp_mask, PG_SAFE);
218 }
219 
220 unsigned long get_safe_page(gfp_t gfp_mask)
221 {
222         return (unsigned long)__get_safe_page(gfp_mask);
223 }
224 
225 static struct page *alloc_image_page(gfp_t gfp_mask)
226 {
227         struct page *page;
228 
229         page = alloc_page(gfp_mask);
230         if (page) {
231                 swsusp_set_page_forbidden(page);
232                 swsusp_set_page_free(page);
233         }
234         return page;
235 }
236 
237 static void recycle_safe_page(void *page_address)
238 {
239         struct linked_page *lp = page_address;
240 
241         lp->next = safe_pages_list;
242         safe_pages_list = lp;
243 }
244 
245 /**
246  * free_image_page - Free a page allocated for hibernation image.
247  * @addr: Address of the page to free.
248  * @clear_nosave_free: If set, clear the PageNosaveFree bit for the page.
249  *
250  * The page to free should have been allocated by get_image_page() (page flags
251  * set by it are affected).
252  */
253 static inline void free_image_page(void *addr, int clear_nosave_free)
254 {
255         struct page *page;
256 
257         BUG_ON(!virt_addr_valid(addr));
258 
259         page = virt_to_page(addr);
260 
261         swsusp_unset_page_forbidden(page);
262         if (clear_nosave_free)
263                 swsusp_unset_page_free(page);
264 
265         __free_page(page);
266 }
267 
268 static inline void free_list_of_pages(struct linked_page *list,
269                                       int clear_page_nosave)
270 {
271         while (list) {
272                 struct linked_page *lp = list->next;
273 
274                 free_image_page(list, clear_page_nosave);
275                 list = lp;
276         }
277 }
278 
279 /*
280  * struct chain_allocator is used for allocating small objects out of
281  * a linked list of pages called 'the chain'.
282  *
283  * The chain grows each time when there is no room for a new object in
284  * the current page.  The allocated objects cannot be freed individually.
285  * It is only possible to free them all at once, by freeing the entire
286  * chain.
287  *
288  * NOTE: The chain allocator may be inefficient if the allocated objects
289  * are not much smaller than PAGE_SIZE.
290  */
291 struct chain_allocator {
292         struct linked_page *chain;      /* the chain */
293         unsigned int used_space;        /* total size of objects allocated out
294                                            of the current page */
295         gfp_t gfp_mask;         /* mask for allocating pages */
296         int safe_needed;        /* if set, only "safe" pages are allocated */
297 };
298 
299 static void chain_init(struct chain_allocator *ca, gfp_t gfp_mask,
300                        int safe_needed)
301 {
302         ca->chain = NULL;
303         ca->used_space = LINKED_PAGE_DATA_SIZE;
304         ca->gfp_mask = gfp_mask;
305         ca->safe_needed = safe_needed;
306 }
307 
308 static void *chain_alloc(struct chain_allocator *ca, unsigned int size)
309 {
310         void *ret;
311 
312         if (LINKED_PAGE_DATA_SIZE - ca->used_space < size) {
313                 struct linked_page *lp;
314 
315                 lp = ca->safe_needed ? __get_safe_page(ca->gfp_mask) :
316                                         get_image_page(ca->gfp_mask, PG_ANY);
317                 if (!lp)
318                         return NULL;
319 
320                 lp->next = ca->chain;
321                 ca->chain = lp;
322                 ca->used_space = 0;
323         }
324         ret = ca->chain->data + ca->used_space;
325         ca->used_space += size;
326         return ret;
327 }
328 
329 /**
330  * Data types related to memory bitmaps.
331  *
332  * Memory bitmap is a structure consisting of many linked lists of
333  * objects.  The main list's elements are of type struct zone_bitmap
334  * and each of them corresonds to one zone.  For each zone bitmap
335  * object there is a list of objects of type struct bm_block that
336  * represent each blocks of bitmap in which information is stored.
337  *
338  * struct memory_bitmap contains a pointer to the main list of zone
339  * bitmap objects, a struct bm_position used for browsing the bitmap,
340  * and a pointer to the list of pages used for allocating all of the
341  * zone bitmap objects and bitmap block objects.
342  *
343  * NOTE: It has to be possible to lay out the bitmap in memory
344  * using only allocations of order 0.  Additionally, the bitmap is
345  * designed to work with arbitrary number of zones (this is over the
346  * top for now, but let's avoid making unnecessary assumptions ;-).
347  *
348  * struct zone_bitmap contains a pointer to a list of bitmap block
349  * objects and a pointer to the bitmap block object that has been
350  * most recently used for setting bits.  Additionally, it contains the
351  * PFNs that correspond to the start and end of the represented zone.
352  *
353  * struct bm_block contains a pointer to the memory page in which
354  * information is stored (in the form of a block of bitmap)
355  * It also contains the pfns that correspond to the start and end of
356  * the represented memory area.
357  *
358  * The memory bitmap is organized as a radix tree to guarantee fast random
359  * access to the bits. There is one radix tree for each zone (as returned
360  * from create_mem_extents).
361  *
362  * One radix tree is represented by one struct mem_zone_bm_rtree. There are
363  * two linked lists for the nodes of the tree, one for the inner nodes and
364  * one for the leave nodes. The linked leave nodes are used for fast linear
365  * access of the memory bitmap.
366  *
367  * The struct rtree_node represents one node of the radix tree.
368  */
369 
370 #define BM_END_OF_MAP   (~0UL)
371 
372 #define BM_BITS_PER_BLOCK       (PAGE_SIZE * BITS_PER_BYTE)
373 #define BM_BLOCK_SHIFT          (PAGE_SHIFT + 3)
374 #define BM_BLOCK_MASK           ((1UL << BM_BLOCK_SHIFT) - 1)
375 
376 /*
377  * struct rtree_node is a wrapper struct to link the nodes
378  * of the rtree together for easy linear iteration over
379  * bits and easy freeing
380  */
381 struct rtree_node {
382         struct list_head list;
383         unsigned long *data;
384 };
385 
386 /*
387  * struct mem_zone_bm_rtree represents a bitmap used for one
388  * populated memory zone.
389  */
390 struct mem_zone_bm_rtree {
391         struct list_head list;          /* Link Zones together         */
392         struct list_head nodes;         /* Radix Tree inner nodes      */
393         struct list_head leaves;        /* Radix Tree leaves           */
394         unsigned long start_pfn;        /* Zone start page frame       */
395         unsigned long end_pfn;          /* Zone end page frame + 1     */
396         struct rtree_node *rtree;       /* Radix Tree Root             */
397         int levels;                     /* Number of Radix Tree Levels */
398         unsigned int blocks;            /* Number of Bitmap Blocks     */
399 };
400 
401 /* strcut bm_position is used for browsing memory bitmaps */
402 
403 struct bm_position {
404         struct mem_zone_bm_rtree *zone;
405         struct rtree_node *node;
406         unsigned long node_pfn;
407         int node_bit;
408 };
409 
410 struct memory_bitmap {
411         struct list_head zones;
412         struct linked_page *p_list;     /* list of pages used to store zone
413                                            bitmap objects and bitmap block
414                                            objects */
415         struct bm_position cur; /* most recently used bit position */
416 };
417 
418 /* Functions that operate on memory bitmaps */
419 
420 #define BM_ENTRIES_PER_LEVEL    (PAGE_SIZE / sizeof(unsigned long))
421 #if BITS_PER_LONG == 32
422 #define BM_RTREE_LEVEL_SHIFT    (PAGE_SHIFT - 2)
423 #else
424 #define BM_RTREE_LEVEL_SHIFT    (PAGE_SHIFT - 3)
425 #endif
426 #define BM_RTREE_LEVEL_MASK     ((1UL << BM_RTREE_LEVEL_SHIFT) - 1)
427 
428 /**
429  * alloc_rtree_node - Allocate a new node and add it to the radix tree.
430  *
431  * This function is used to allocate inner nodes as well as the
432  * leave nodes of the radix tree. It also adds the node to the
433  * corresponding linked list passed in by the *list parameter.
434  */
435 static struct rtree_node *alloc_rtree_node(gfp_t gfp_mask, int safe_needed,
436                                            struct chain_allocator *ca,
437                                            struct list_head *list)
438 {
439         struct rtree_node *node;
440 
441         node = chain_alloc(ca, sizeof(struct rtree_node));
442         if (!node)
443                 return NULL;
444 
445         node->data = get_image_page(gfp_mask, safe_needed);
446         if (!node->data)
447                 return NULL;
448 
449         list_add_tail(&node->list, list);
450 
451         return node;
452 }
453 
454 /**
455  * add_rtree_block - Add a new leave node to the radix tree.
456  *
457  * The leave nodes need to be allocated in order to keep the leaves
458  * linked list in order. This is guaranteed by the zone->blocks
459  * counter.
460  */
461 static int add_rtree_block(struct mem_zone_bm_rtree *zone, gfp_t gfp_mask,
462                            int safe_needed, struct chain_allocator *ca)
463 {
464         struct rtree_node *node, *block, **dst;
465         unsigned int levels_needed, block_nr;
466         int i;
467 
468         block_nr = zone->blocks;
469         levels_needed = 0;
470 
471         /* How many levels do we need for this block nr? */
472         while (block_nr) {
473                 levels_needed += 1;
474                 block_nr >>= BM_RTREE_LEVEL_SHIFT;
475         }
476 
477         /* Make sure the rtree has enough levels */
478         for (i = zone->levels; i < levels_needed; i++) {
479                 node = alloc_rtree_node(gfp_mask, safe_needed, ca,
480                                         &zone->nodes);
481                 if (!node)
482                         return -ENOMEM;
483 
484                 node->data[0] = (unsigned long)zone->rtree;
485                 zone->rtree = node;
486                 zone->levels += 1;
487         }
488 
489         /* Allocate new block */
490         block = alloc_rtree_node(gfp_mask, safe_needed, ca, &zone->leaves);
491         if (!block)
492                 return -ENOMEM;
493 
494         /* Now walk the rtree to insert the block */
495         node = zone->rtree;
496         dst = &zone->rtree;
497         block_nr = zone->blocks;
498         for (i = zone->levels; i > 0; i--) {
499                 int index;
500 
501                 if (!node) {
502                         node = alloc_rtree_node(gfp_mask, safe_needed, ca,
503                                                 &zone->nodes);
504                         if (!node)
505                                 return -ENOMEM;
506                         *dst = node;
507                 }
508 
509                 index = block_nr >> ((i - 1) * BM_RTREE_LEVEL_SHIFT);
510                 index &= BM_RTREE_LEVEL_MASK;
511                 dst = (struct rtree_node **)&((*dst)->data[index]);
512                 node = *dst;
513         }
514 
515         zone->blocks += 1;
516         *dst = block;
517 
518         return 0;
519 }
520 
521 static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
522                                int clear_nosave_free);
523 
524 /**
525  * create_zone_bm_rtree - Create a radix tree for one zone.
526  *
527  * Allocated the mem_zone_bm_rtree structure and initializes it.
528  * This function also allocated and builds the radix tree for the
529  * zone.
530  */
531 static struct mem_zone_bm_rtree *create_zone_bm_rtree(gfp_t gfp_mask,
532                                                       int safe_needed,
533                                                       struct chain_allocator *ca,
534                                                       unsigned long start,
535                                                       unsigned long end)
536 {
537         struct mem_zone_bm_rtree *zone;
538         unsigned int i, nr_blocks;
539         unsigned long pages;
540 
541         pages = end - start;
542         zone  = chain_alloc(ca, sizeof(struct mem_zone_bm_rtree));
543         if (!zone)
544                 return NULL;
545 
546         INIT_LIST_HEAD(&zone->nodes);
547         INIT_LIST_HEAD(&zone->leaves);
548         zone->start_pfn = start;
549         zone->end_pfn = end;
550         nr_blocks = DIV_ROUND_UP(pages, BM_BITS_PER_BLOCK);
551 
552         for (i = 0; i < nr_blocks; i++) {
553                 if (add_rtree_block(zone, gfp_mask, safe_needed, ca)) {
554                         free_zone_bm_rtree(zone, PG_UNSAFE_CLEAR);
555                         return NULL;
556                 }
557         }
558 
559         return zone;
560 }
561 
562 /**
563  * free_zone_bm_rtree - Free the memory of the radix tree.
564  *
565  * Free all node pages of the radix tree. The mem_zone_bm_rtree
566  * structure itself is not freed here nor are the rtree_node
567  * structs.
568  */
569 static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
570                                int clear_nosave_free)
571 {
572         struct rtree_node *node;
573 
574         list_for_each_entry(node, &zone->nodes, list)
575                 free_image_page(node->data, clear_nosave_free);
576 
577         list_for_each_entry(node, &zone->leaves, list)
578                 free_image_page(node->data, clear_nosave_free);
579 }
580 
581 static void memory_bm_position_reset(struct memory_bitmap *bm)
582 {
583         bm->cur.zone = list_entry(bm->zones.next, struct mem_zone_bm_rtree,
584                                   list);
585         bm->cur.node = list_entry(bm->cur.zone->leaves.next,
586                                   struct rtree_node, list);
587         bm->cur.node_pfn = 0;
588         bm->cur.node_bit = 0;
589 }
590 
591 static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free);
592 
593 struct mem_extent {
594         struct list_head hook;
595         unsigned long start;
596         unsigned long end;
597 };
598 
599 /**
600  * free_mem_extents - Free a list of memory extents.
601  * @list: List of extents to free.
602  */
603 static void free_mem_extents(struct list_head *list)
604 {
605         struct mem_extent *ext, *aux;
606 
607         list_for_each_entry_safe(ext, aux, list, hook) {
608                 list_del(&ext->hook);
609                 kfree(ext);
610         }
611 }
612 
613 /**
614  * create_mem_extents - Create a list of memory extents.
615  * @list: List to put the extents into.
616  * @gfp_mask: Mask to use for memory allocations.
617  *
618  * The extents represent contiguous ranges of PFNs.
619  */
620 static int create_mem_extents(struct list_head *list, gfp_t gfp_mask)
621 {
622         struct zone *zone;
623 
624         INIT_LIST_HEAD(list);
625 
626         for_each_populated_zone(zone) {
627                 unsigned long zone_start, zone_end;
628                 struct mem_extent *ext, *cur, *aux;
629 
630                 zone_start = zone->zone_start_pfn;
631                 zone_end = zone_end_pfn(zone);
632 
633                 list_for_each_entry(ext, list, hook)
634                         if (zone_start <= ext->end)
635                                 break;
636 
637                 if (&ext->hook == list || zone_end < ext->start) {
638                         /* New extent is necessary */
639                         struct mem_extent *new_ext;
640 
641                         new_ext = kzalloc(sizeof(struct mem_extent), gfp_mask);
642                         if (!new_ext) {
643                                 free_mem_extents(list);
644                                 return -ENOMEM;
645                         }
646                         new_ext->start = zone_start;
647                         new_ext->end = zone_end;
648                         list_add_tail(&new_ext->hook, &ext->hook);
649                         continue;
650                 }
651 
652                 /* Merge this zone's range of PFNs with the existing one */
653                 if (zone_start < ext->start)
654                         ext->start = zone_start;
655                 if (zone_end > ext->end)
656                         ext->end = zone_end;
657 
658                 /* More merging may be possible */
659                 cur = ext;
660                 list_for_each_entry_safe_continue(cur, aux, list, hook) {
661                         if (zone_end < cur->start)
662                                 break;
663                         if (zone_end < cur->end)
664                                 ext->end = cur->end;
665                         list_del(&cur->hook);
666                         kfree(cur);
667                 }
668         }
669 
670         return 0;
671 }
672 
673 /**
674  * memory_bm_create - Allocate memory for a memory bitmap.
675  */
676 static int memory_bm_create(struct memory_bitmap *bm, gfp_t gfp_mask,
677                             int safe_needed)
678 {
679         struct chain_allocator ca;
680         struct list_head mem_extents;
681         struct mem_extent *ext;
682         int error;
683 
684         chain_init(&ca, gfp_mask, safe_needed);
685         INIT_LIST_HEAD(&bm->zones);
686 
687         error = create_mem_extents(&mem_extents, gfp_mask);
688         if (error)
689                 return error;
690 
691         list_for_each_entry(ext, &mem_extents, hook) {
692                 struct mem_zone_bm_rtree *zone;
693 
694                 zone = create_zone_bm_rtree(gfp_mask, safe_needed, &ca,
695                                             ext->start, ext->end);
696                 if (!zone) {
697                         error = -ENOMEM;
698                         goto Error;
699                 }
700                 list_add_tail(&zone->list, &bm->zones);
701         }
702 
703         bm->p_list = ca.chain;
704         memory_bm_position_reset(bm);
705  Exit:
706         free_mem_extents(&mem_extents);
707         return error;
708 
709  Error:
710         bm->p_list = ca.chain;
711         memory_bm_free(bm, PG_UNSAFE_CLEAR);
712         goto Exit;
713 }
714 
715 /**
716  * memory_bm_free - Free memory occupied by the memory bitmap.
717  * @bm: Memory bitmap.
718  */
719 static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free)
720 {
721         struct mem_zone_bm_rtree *zone;
722 
723         list_for_each_entry(zone, &bm->zones, list)
724                 free_zone_bm_rtree(zone, clear_nosave_free);
725 
726         free_list_of_pages(bm->p_list, clear_nosave_free);
727 
728         INIT_LIST_HEAD(&bm->zones);
729 }
730 
731 /**
732  * memory_bm_find_bit - Find the bit for a given PFN in a memory bitmap.
733  *
734  * Find the bit in memory bitmap @bm that corresponds to the given PFN.
735  * The cur.zone, cur.block and cur.node_pfn members of @bm are updated.
736  *
737  * Walk the radix tree to find the page containing the bit that represents @pfn
738  * and return the position of the bit in @addr and @bit_nr.
739  */
740 static int memory_bm_find_bit(struct memory_bitmap *bm, unsigned long pfn,
741                               void **addr, unsigned int *bit_nr)
742 {
743         struct mem_zone_bm_rtree *curr, *zone;
744         struct rtree_node *node;
745         int i, block_nr;
746 
747         zone = bm->cur.zone;
748 
749         if (pfn >= zone->start_pfn && pfn < zone->end_pfn)
750                 goto zone_found;
751 
752         zone = NULL;
753 
754         /* Find the right zone */
755         list_for_each_entry(curr, &bm->zones, list) {
756                 if (pfn >= curr->start_pfn && pfn < curr->end_pfn) {
757                         zone = curr;
758                         break;
759                 }
760         }
761 
762         if (!zone)
763                 return -EFAULT;
764 
765 zone_found:
766         /*
767          * We have found the zone. Now walk the radix tree to find the leaf node
768          * for our PFN.
769          */
770 
771         /*
772          * If the zone we wish to scan is the current zone and the
773          * pfn falls into the current node then we do not need to walk
774          * the tree.
775          */
776         node = bm->cur.node;
777         if (zone == bm->cur.zone &&
778             ((pfn - zone->start_pfn) & ~BM_BLOCK_MASK) == bm->cur.node_pfn)
779                 goto node_found;
780 
781         node      = zone->rtree;
782         block_nr  = (pfn - zone->start_pfn) >> BM_BLOCK_SHIFT;
783 
784         for (i = zone->levels; i > 0; i--) {
785                 int index;
786 
787                 index = block_nr >> ((i - 1) * BM_RTREE_LEVEL_SHIFT);
788                 index &= BM_RTREE_LEVEL_MASK;
789                 BUG_ON(node->data[index] == 0);
790                 node = (struct rtree_node *)node->data[index];
791         }
792 
793 node_found:
794         /* Update last position */
795         bm->cur.zone = zone;
796         bm->cur.node = node;
797         bm->cur.node_pfn = (pfn - zone->start_pfn) & ~BM_BLOCK_MASK;
798 
799         /* Set return values */
800         *addr = node->data;
801         *bit_nr = (pfn - zone->start_pfn) & BM_BLOCK_MASK;
802 
803         return 0;
804 }
805 
806 static void memory_bm_set_bit(struct memory_bitmap *bm, unsigned long pfn)
807 {
808         void *addr;
809         unsigned int bit;
810         int error;
811 
812         error = memory_bm_find_bit(bm, pfn, &addr, &bit);
813         BUG_ON(error);
814         set_bit(bit, addr);
815 }
816 
817 static int mem_bm_set_bit_check(struct memory_bitmap *bm, unsigned long pfn)
818 {
819         void *addr;
820         unsigned int bit;
821         int error;
822 
823         error = memory_bm_find_bit(bm, pfn, &addr, &bit);
824         if (!error)
825                 set_bit(bit, addr);
826 
827         return error;
828 }
829 
830 static void memory_bm_clear_bit(struct memory_bitmap *bm, unsigned long pfn)
831 {
832         void *addr;
833         unsigned int bit;
834         int error;
835 
836         error = memory_bm_find_bit(bm, pfn, &addr, &bit);
837         BUG_ON(error);
838         clear_bit(bit, addr);
839 }
840 
841 static void memory_bm_clear_current(struct memory_bitmap *bm)
842 {
843         int bit;
844 
845         bit = max(bm->cur.node_bit - 1, 0);
846         clear_bit(bit, bm->cur.node->data);
847 }
848 
849 static int memory_bm_test_bit(struct memory_bitmap *bm, unsigned long pfn)
850 {
851         void *addr;
852         unsigned int bit;
853         int error;
854 
855         error = memory_bm_find_bit(bm, pfn, &addr, &bit);
856         BUG_ON(error);
857         return test_bit(bit, addr);
858 }
859 
860 static bool memory_bm_pfn_present(struct memory_bitmap *bm, unsigned long pfn)
861 {
862         void *addr;
863         unsigned int bit;
864 
865         return !memory_bm_find_bit(bm, pfn, &addr, &bit);
866 }
867 
868 /*
869  * rtree_next_node - Jump to the next leaf node.
870  *
871  * Set the position to the beginning of the next node in the
872  * memory bitmap. This is either the next node in the current
873  * zone's radix tree or the first node in the radix tree of the
874  * next zone.
875  *
876  * Return true if there is a next node, false otherwise.
877  */
878 static bool rtree_next_node(struct memory_bitmap *bm)
879 {
880         if (!list_is_last(&bm->cur.node->list, &bm->cur.zone->leaves)) {
881                 bm->cur.node = list_entry(bm->cur.node->list.next,
882                                           struct rtree_node, list);
883                 bm->cur.node_pfn += BM_BITS_PER_BLOCK;
884                 bm->cur.node_bit  = 0;
885                 touch_softlockup_watchdog();
886                 return true;
887         }
888 
889         /* No more nodes, goto next zone */
890         if (!list_is_last(&bm->cur.zone->list, &bm->zones)) {
891                 bm->cur.zone = list_entry(bm->cur.zone->list.next,
892                                   struct mem_zone_bm_rtree, list);
893                 bm->cur.node = list_entry(bm->cur.zone->leaves.next,
894                                           struct rtree_node, list);
895                 bm->cur.node_pfn = 0;
896                 bm->cur.node_bit = 0;
897                 return true;
898         }
899 
900         /* No more zones */
901         return false;
902 }
903 
904 /**
905  * memory_bm_rtree_next_pfn - Find the next set bit in a memory bitmap.
906  * @bm: Memory bitmap.
907  *
908  * Starting from the last returned position this function searches for the next
909  * set bit in @bm and returns the PFN represented by it.  If no more bits are
910  * set, BM_END_OF_MAP is returned.
911  *
912  * It is required to run memory_bm_position_reset() before the first call to
913  * this function for the given memory bitmap.
914  */
915 static unsigned long memory_bm_next_pfn(struct memory_bitmap *bm)
916 {
917         unsigned long bits, pfn, pages;
918         int bit;
919 
920         do {
921                 pages     = bm->cur.zone->end_pfn - bm->cur.zone->start_pfn;
922                 bits      = min(pages - bm->cur.node_pfn, BM_BITS_PER_BLOCK);
923                 bit       = find_next_bit(bm->cur.node->data, bits,
924                                           bm->cur.node_bit);
925                 if (bit < bits) {
926                         pfn = bm->cur.zone->start_pfn + bm->cur.node_pfn + bit;
927                         bm->cur.node_bit = bit + 1;
928                         return pfn;
929                 }
930         } while (rtree_next_node(bm));
931 
932         return BM_END_OF_MAP;
933 }
934 
935 /*
936  * This structure represents a range of page frames the contents of which
937  * should not be saved during hibernation.
938  */
939 struct nosave_region {
940         struct list_head list;
941         unsigned long start_pfn;
942         unsigned long end_pfn;
943 };
944 
945 static LIST_HEAD(nosave_regions);
946 
947 static void recycle_zone_bm_rtree(struct mem_zone_bm_rtree *zone)
948 {
949         struct rtree_node *node;
950 
951         list_for_each_entry(node, &zone->nodes, list)
952                 recycle_safe_page(node->data);
953 
954         list_for_each_entry(node, &zone->leaves, list)
955                 recycle_safe_page(node->data);
956 }
957 
958 static void memory_bm_recycle(struct memory_bitmap *bm)
959 {
960         struct mem_zone_bm_rtree *zone;
961         struct linked_page *p_list;
962 
963         list_for_each_entry(zone, &bm->zones, list)
964                 recycle_zone_bm_rtree(zone);
965 
966         p_list = bm->p_list;
967         while (p_list) {
968                 struct linked_page *lp = p_list;
969 
970                 p_list = lp->next;
971                 recycle_safe_page(lp);
972         }
973 }
974 
975 /**
976  * register_nosave_region - Register a region of unsaveable memory.
977  *
978  * Register a range of page frames the contents of which should not be saved
979  * during hibernation (to be used in the early initialization code).
980  */
981 void __init __register_nosave_region(unsigned long start_pfn,
982                                      unsigned long end_pfn, int use_kmalloc)
983 {
984         struct nosave_region *region;
985 
986         if (start_pfn >= end_pfn)
987                 return;
988 
989         if (!list_empty(&nosave_regions)) {
990                 /* Try to extend the previous region (they should be sorted) */
991                 region = list_entry(nosave_regions.prev,
992                                         struct nosave_region, list);
993                 if (region->end_pfn == start_pfn) {
994                         region->end_pfn = end_pfn;
995                         goto Report;
996                 }
997         }
998         if (use_kmalloc) {
999                 /* During init, this shouldn't fail */
1000                 region = kmalloc(sizeof(struct nosave_region), GFP_KERNEL);
1001                 BUG_ON(!region);
1002         } else {
1003                 /* This allocation cannot fail */
1004                 region = memblock_alloc(sizeof(struct nosave_region),
1005                                         SMP_CACHE_BYTES);
1006                 if (!region)
1007                         panic("%s: Failed to allocate %zu bytes\n", __func__,
1008                               sizeof(struct nosave_region));
1009         }
1010         region->start_pfn = start_pfn;
1011         region->end_pfn = end_pfn;
1012         list_add_tail(&region->list, &nosave_regions);
1013  Report:
1014         pr_info("Registered nosave memory: [mem %#010llx-%#010llx]\n",
1015                 (unsigned long long) start_pfn << PAGE_SHIFT,
1016                 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
1017 }
1018 
1019 /*
1020  * Set bits in this map correspond to the page frames the contents of which
1021  * should not be saved during the suspend.
1022  */
1023 static struct memory_bitmap *forbidden_pages_map;
1024 
1025 /* Set bits in this map correspond to free page frames. */
1026 static struct memory_bitmap *free_pages_map;
1027 
1028 /*
1029  * Each page frame allocated for creating the image is marked by setting the
1030  * corresponding bits in forbidden_pages_map and free_pages_map simultaneously
1031  */
1032 
1033 void swsusp_set_page_free(struct page *page)
1034 {
1035         if (free_pages_map)
1036                 memory_bm_set_bit(free_pages_map, page_to_pfn(page));
1037 }
1038 
1039 static int swsusp_page_is_free(struct page *page)
1040 {
1041         return free_pages_map ?
1042                 memory_bm_test_bit(free_pages_map, page_to_pfn(page)) : 0;
1043 }
1044 
1045 void swsusp_unset_page_free(struct page *page)
1046 {
1047         if (free_pages_map)
1048                 memory_bm_clear_bit(free_pages_map, page_to_pfn(page));
1049 }
1050 
1051 static void swsusp_set_page_forbidden(struct page *page)
1052 {
1053         if (forbidden_pages_map)
1054                 memory_bm_set_bit(forbidden_pages_map, page_to_pfn(page));
1055 }
1056 
1057 int swsusp_page_is_forbidden(struct page *page)
1058 {
1059         return forbidden_pages_map ?
1060                 memory_bm_test_bit(forbidden_pages_map, page_to_pfn(page)) : 0;
1061 }
1062 
1063 static void swsusp_unset_page_forbidden(struct page *page)
1064 {
1065         if (forbidden_pages_map)
1066                 memory_bm_clear_bit(forbidden_pages_map, page_to_pfn(page));
1067 }
1068 
1069 /**
1070  * mark_nosave_pages - Mark pages that should not be saved.
1071  * @bm: Memory bitmap.
1072  *
1073  * Set the bits in @bm that correspond to the page frames the contents of which
1074  * should not be saved.
1075  */
1076 static void mark_nosave_pages(struct memory_bitmap *bm)
1077 {
1078         struct nosave_region *region;
1079 
1080         if (list_empty(&nosave_regions))
1081                 return;
1082 
1083         list_for_each_entry(region, &nosave_regions, list) {
1084                 unsigned long pfn;
1085 
1086                 pr_debug("Marking nosave pages: [mem %#010llx-%#010llx]\n",
1087                          (unsigned long long) region->start_pfn << PAGE_SHIFT,
1088                          ((unsigned long long) region->end_pfn << PAGE_SHIFT)
1089                                 - 1);
1090 
1091                 for (pfn = region->start_pfn; pfn < region->end_pfn; pfn++)
1092                         if (pfn_valid(pfn)) {
1093                                 /*
1094                                  * It is safe to ignore the result of
1095                                  * mem_bm_set_bit_check() here, since we won't
1096                                  * touch the PFNs for which the error is
1097                                  * returned anyway.
1098                                  */
1099                                 mem_bm_set_bit_check(bm, pfn);
1100                         }
1101         }
1102 }
1103 
1104 /**
1105  * create_basic_memory_bitmaps - Create bitmaps to hold basic page information.
1106  *
1107  * Create bitmaps needed for marking page frames that should not be saved and
1108  * free page frames.  The forbidden_pages_map and free_pages_map pointers are
1109  * only modified if everything goes well, because we don't want the bits to be
1110  * touched before both bitmaps are set up.
1111  */
1112 int create_basic_memory_bitmaps(void)
1113 {
1114         struct memory_bitmap *bm1, *bm2;
1115         int error = 0;
1116 
1117         if (forbidden_pages_map && free_pages_map)
1118                 return 0;
1119         else
1120                 BUG_ON(forbidden_pages_map || free_pages_map);
1121 
1122         bm1 = kzalloc(sizeof(struct memory_bitmap), GFP_KERNEL);
1123         if (!bm1)
1124                 return -ENOMEM;
1125 
1126         error = memory_bm_create(bm1, GFP_KERNEL, PG_ANY);
1127         if (error)
1128                 goto Free_first_object;
1129 
1130         bm2 = kzalloc(sizeof(struct memory_bitmap), GFP_KERNEL);
1131         if (!bm2)
1132                 goto Free_first_bitmap;
1133 
1134         error = memory_bm_create(bm2, GFP_KERNEL, PG_ANY);
1135         if (error)
1136                 goto Free_second_object;
1137 
1138         forbidden_pages_map = bm1;
1139         free_pages_map = bm2;
1140         mark_nosave_pages(forbidden_pages_map);
1141 
1142         pr_debug("Basic memory bitmaps created\n");
1143 
1144         return 0;
1145 
1146  Free_second_object:
1147         kfree(bm2);
1148  Free_first_bitmap:
1149         memory_bm_free(bm1, PG_UNSAFE_CLEAR);
1150  Free_first_object:
1151         kfree(bm1);
1152         return -ENOMEM;
1153 }
1154 
1155 /**
1156  * free_basic_memory_bitmaps - Free memory bitmaps holding basic information.
1157  *
1158  * Free memory bitmaps allocated by create_basic_memory_bitmaps().  The
1159  * auxiliary pointers are necessary so that the bitmaps themselves are not
1160  * referred to while they are being freed.
1161  */
1162 void free_basic_memory_bitmaps(void)
1163 {
1164         struct memory_bitmap *bm1, *bm2;
1165 
1166         if (WARN_ON(!(forbidden_pages_map && free_pages_map)))
1167                 return;
1168 
1169         bm1 = forbidden_pages_map;
1170         bm2 = free_pages_map;
1171         forbidden_pages_map = NULL;
1172         free_pages_map = NULL;
1173         memory_bm_free(bm1, PG_UNSAFE_CLEAR);
1174         kfree(bm1);
1175         memory_bm_free(bm2, PG_UNSAFE_CLEAR);
1176         kfree(bm2);
1177 
1178         pr_debug("Basic memory bitmaps freed\n");
1179 }
1180 
1181 static void clear_or_poison_free_page(struct page *page)
1182 {
1183         if (page_poisoning_enabled_static())
1184                 __kernel_poison_pages(page, 1);
1185         else if (want_init_on_free())
1186                 clear_highpage(page);
1187 }
1188 
1189 void clear_or_poison_free_pages(void)
1190 {
1191         struct memory_bitmap *bm = free_pages_map;
1192         unsigned long pfn;
1193 
1194         if (WARN_ON(!(free_pages_map)))
1195                 return;
1196 
1197         if (page_poisoning_enabled() || want_init_on_free()) {
1198                 memory_bm_position_reset(bm);
1199                 pfn = memory_bm_next_pfn(bm);
1200                 while (pfn != BM_END_OF_MAP) {
1201                         if (pfn_valid(pfn))
1202                                 clear_or_poison_free_page(pfn_to_page(pfn));
1203 
1204                         pfn = memory_bm_next_pfn(bm);
1205                 }
1206                 memory_bm_position_reset(bm);
1207                 pr_info("free pages cleared after restore\n");
1208         }
1209 }
1210 
1211 /**
1212  * snapshot_additional_pages - Estimate the number of extra pages needed.
1213  * @zone: Memory zone to carry out the computation for.
1214  *
1215  * Estimate the number of additional pages needed for setting up a hibernation
1216  * image data structures for @zone (usually, the returned value is greater than
1217  * the exact number).
1218  */
1219 unsigned int snapshot_additional_pages(struct zone *zone)
1220 {
1221         unsigned int rtree, nodes;
1222 
1223         rtree = nodes = DIV_ROUND_UP(zone->spanned_pages, BM_BITS_PER_BLOCK);
1224         rtree += DIV_ROUND_UP(rtree * sizeof(struct rtree_node),
1225                               LINKED_PAGE_DATA_SIZE);
1226         while (nodes > 1) {
1227                 nodes = DIV_ROUND_UP(nodes, BM_ENTRIES_PER_LEVEL);
1228                 rtree += nodes;
1229         }
1230 
1231         return 2 * rtree;
1232 }
1233 
1234 #ifdef CONFIG_HIGHMEM
1235 /**
1236  * count_free_highmem_pages - Compute the total number of free highmem pages.
1237  *
1238  * The returned number is system-wide.
1239  */
1240 static unsigned int count_free_highmem_pages(void)
1241 {
1242         struct zone *zone;
1243         unsigned int cnt = 0;
1244 
1245         for_each_populated_zone(zone)
1246                 if (is_highmem(zone))
1247                         cnt += zone_page_state(zone, NR_FREE_PAGES);
1248 
1249         return cnt;
1250 }
1251 
1252 /**
1253  * saveable_highmem_page - Check if a highmem page is saveable.
1254  *
1255  * Determine whether a highmem page should be included in a hibernation image.
1256  *
1257  * We should save the page if it isn't Nosave or NosaveFree, or Reserved,
1258  * and it isn't part of a free chunk of pages.
1259  */
1260 static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
1261 {
1262         struct page *page;
1263 
1264         if (!pfn_valid(pfn))
1265                 return NULL;
1266 
1267         page = pfn_to_online_page(pfn);
1268         if (!page || page_zone(page) != zone)
1269                 return NULL;
1270 
1271         BUG_ON(!PageHighMem(page));
1272 
1273         if (swsusp_page_is_forbidden(page) ||  swsusp_page_is_free(page))
1274                 return NULL;
1275 
1276         if (PageReserved(page) || PageOffline(page))
1277                 return NULL;
1278 
1279         if (page_is_guard(page))
1280                 return NULL;
1281 
1282         return page;
1283 }
1284 
1285 /**
1286  * count_highmem_pages - Compute the total number of saveable highmem pages.
1287  */
1288 static unsigned int count_highmem_pages(void)
1289 {
1290         struct zone *zone;
1291         unsigned int n = 0;
1292 
1293         for_each_populated_zone(zone) {
1294                 unsigned long pfn, max_zone_pfn;
1295 
1296                 if (!is_highmem(zone))
1297                         continue;
1298 
1299                 mark_free_pages(zone);
1300                 max_zone_pfn = zone_end_pfn(zone);
1301                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
1302                         if (saveable_highmem_page(zone, pfn))
1303                                 n++;
1304         }
1305         return n;
1306 }
1307 #else
1308 static inline void *saveable_highmem_page(struct zone *z, unsigned long p)
1309 {
1310         return NULL;
1311 }
1312 #endif /* CONFIG_HIGHMEM */
1313 
1314 /**
1315  * saveable_page - Check if the given page is saveable.
1316  *
1317  * Determine whether a non-highmem page should be included in a hibernation
1318  * image.
1319  *
1320  * We should save the page if it isn't Nosave, and is not in the range
1321  * of pages statically defined as 'unsaveable', and it isn't part of
1322  * a free chunk of pages.
1323  */
1324 static struct page *saveable_page(struct zone *zone, unsigned long pfn)
1325 {
1326         struct page *page;
1327 
1328         if (!pfn_valid(pfn))
1329                 return NULL;
1330 
1331         page = pfn_to_online_page(pfn);
1332         if (!page || page_zone(page) != zone)
1333                 return NULL;
1334 
1335         BUG_ON(PageHighMem(page));
1336 
1337         if (swsusp_page_is_forbidden(page) || swsusp_page_is_free(page))
1338                 return NULL;
1339 
1340         if (PageOffline(page))
1341                 return NULL;
1342 
1343         if (PageReserved(page)
1344             && (!kernel_page_present(page) || pfn_is_nosave(pfn)))
1345                 return NULL;
1346 
1347         if (page_is_guard(page))
1348                 return NULL;
1349 
1350         return page;
1351 }
1352 
1353 /**
1354  * count_data_pages - Compute the total number of saveable non-highmem pages.
1355  */
1356 static unsigned int count_data_pages(void)
1357 {
1358         struct zone *zone;
1359         unsigned long pfn, max_zone_pfn;
1360         unsigned int n = 0;
1361 
1362         for_each_populated_zone(zone) {
1363                 if (is_highmem(zone))
1364                         continue;
1365 
1366                 mark_free_pages(zone);
1367                 max_zone_pfn = zone_end_pfn(zone);
1368                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
1369                         if (saveable_page(zone, pfn))
1370                                 n++;
1371         }
1372         return n;
1373 }
1374 
1375 /*
1376  * This is needed, because copy_page and memcpy are not usable for copying
1377  * task structs.
1378  */
1379 static inline void do_copy_page(long *dst, long *src)
1380 {
1381         int n;
1382 
1383         for (n = PAGE_SIZE / sizeof(long); n; n--)
1384                 *dst++ = *src++;
1385 }
1386 
1387 /**
1388  * safe_copy_page - Copy a page in a safe way.
1389  *
1390  * Check if the page we are going to copy is marked as present in the kernel
1391  * page tables. This always is the case if CONFIG_DEBUG_PAGEALLOC or
1392  * CONFIG_ARCH_HAS_SET_DIRECT_MAP is not set. In that case kernel_page_present()
1393  * always returns 'true'.
1394  */
1395 static void safe_copy_page(void *dst, struct page *s_page)
1396 {
1397         if (kernel_page_present(s_page)) {
1398                 do_copy_page(dst, page_address(s_page));
1399         } else {
1400                 hibernate_map_page(s_page);
1401                 do_copy_page(dst, page_address(s_page));
1402                 hibernate_unmap_page(s_page);
1403         }
1404 }
1405 
1406 #ifdef CONFIG_HIGHMEM
1407 static inline struct page *page_is_saveable(struct zone *zone, unsigned long pfn)
1408 {
1409         return is_highmem(zone) ?
1410                 saveable_highmem_page(zone, pfn) : saveable_page(zone, pfn);
1411 }
1412 
1413 static void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
1414 {
1415         struct page *s_page, *d_page;
1416         void *src, *dst;
1417 
1418         s_page = pfn_to_page(src_pfn);
1419         d_page = pfn_to_page(dst_pfn);
1420         if (PageHighMem(s_page)) {
1421                 src = kmap_atomic(s_page);
1422                 dst = kmap_atomic(d_page);
1423                 do_copy_page(dst, src);
1424                 kunmap_atomic(dst);
1425                 kunmap_atomic(src);
1426         } else {
1427                 if (PageHighMem(d_page)) {
1428                         /*
1429                          * The page pointed to by src may contain some kernel
1430                          * data modified by kmap_atomic()
1431                          */
1432                         safe_copy_page(buffer, s_page);
1433                         dst = kmap_atomic(d_page);
1434                         copy_page(dst, buffer);
1435                         kunmap_atomic(dst);
1436                 } else {
1437                         safe_copy_page(page_address(d_page), s_page);
1438                 }
1439         }
1440 }
1441 #else
1442 #define page_is_saveable(zone, pfn)     saveable_page(zone, pfn)
1443 
1444 static inline void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
1445 {
1446         safe_copy_page(page_address(pfn_to_page(dst_pfn)),
1447                                 pfn_to_page(src_pfn));
1448 }
1449 #endif /* CONFIG_HIGHMEM */
1450 
1451 static void copy_data_pages(struct memory_bitmap *copy_bm,
1452                             struct memory_bitmap *orig_bm)
1453 {
1454         struct zone *zone;
1455         unsigned long pfn;
1456 
1457         for_each_populated_zone(zone) {
1458                 unsigned long max_zone_pfn;
1459 
1460                 mark_free_pages(zone);
1461                 max_zone_pfn = zone_end_pfn(zone);
1462                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
1463                         if (page_is_saveable(zone, pfn))
1464                                 memory_bm_set_bit(orig_bm, pfn);
1465         }
1466         memory_bm_position_reset(orig_bm);
1467         memory_bm_position_reset(copy_bm);
1468         for(;;) {
1469                 pfn = memory_bm_next_pfn(orig_bm);
1470                 if (unlikely(pfn == BM_END_OF_MAP))
1471                         break;
1472                 copy_data_page(memory_bm_next_pfn(copy_bm), pfn);
1473         }
1474 }
1475 
1476 /* Total number of image pages */
1477 static unsigned int nr_copy_pages;
1478 /* Number of pages needed for saving the original pfns of the image pages */
1479 static unsigned int nr_meta_pages;
1480 /*
1481  * Numbers of normal and highmem page frames allocated for hibernation image
1482  * before suspending devices.
1483  */
1484 static unsigned int alloc_normal, alloc_highmem;
1485 /*
1486  * Memory bitmap used for marking saveable pages (during hibernation) or
1487  * hibernation image pages (during restore)
1488  */
1489 static struct memory_bitmap orig_bm;
1490 /*
1491  * Memory bitmap used during hibernation for marking allocated page frames that
1492  * will contain copies of saveable pages.  During restore it is initially used
1493  * for marking hibernation image pages, but then the set bits from it are
1494  * duplicated in @orig_bm and it is released.  On highmem systems it is next
1495  * used for marking "safe" highmem pages, but it has to be reinitialized for
1496  * this purpose.
1497  */
1498 static struct memory_bitmap copy_bm;
1499 
1500 /**
1501  * swsusp_free - Free pages allocated for hibernation image.
1502  *
1503  * Image pages are alocated before snapshot creation, so they need to be
1504  * released after resume.
1505  */
1506 void swsusp_free(void)
1507 {
1508         unsigned long fb_pfn, fr_pfn;
1509 
1510         if (!forbidden_pages_map || !free_pages_map)
1511                 goto out;
1512 
1513         memory_bm_position_reset(forbidden_pages_map);
1514         memory_bm_position_reset(free_pages_map);
1515 
1516 loop:
1517         fr_pfn = memory_bm_next_pfn(free_pages_map);
1518         fb_pfn = memory_bm_next_pfn(forbidden_pages_map);
1519 
1520         /*
1521          * Find the next bit set in both bitmaps. This is guaranteed to
1522          * terminate when fb_pfn == fr_pfn == BM_END_OF_MAP.
1523          */
1524         do {
1525                 if (fb_pfn < fr_pfn)
1526                         fb_pfn = memory_bm_next_pfn(forbidden_pages_map);
1527                 if (fr_pfn < fb_pfn)
1528                         fr_pfn = memory_bm_next_pfn(free_pages_map);
1529         } while (fb_pfn != fr_pfn);
1530 
1531         if (fr_pfn != BM_END_OF_MAP && pfn_valid(fr_pfn)) {
1532                 struct page *page = pfn_to_page(fr_pfn);
1533 
1534                 memory_bm_clear_current(forbidden_pages_map);
1535                 memory_bm_clear_current(free_pages_map);
1536                 hibernate_restore_unprotect_page(page_address(page));
1537                 __free_page(page);
1538                 goto loop;
1539         }
1540 
1541 out:
1542         nr_copy_pages = 0;
1543         nr_meta_pages = 0;
1544         restore_pblist = NULL;
1545         buffer = NULL;
1546         alloc_normal = 0;
1547         alloc_highmem = 0;
1548         hibernate_restore_protection_end();
1549 }
1550 
1551 /* Helper functions used for the shrinking of memory. */
1552 
1553 #define GFP_IMAGE       (GFP_KERNEL | __GFP_NOWARN)
1554 
1555 /**
1556  * preallocate_image_pages - Allocate a number of pages for hibernation image.
1557  * @nr_pages: Number of page frames to allocate.
1558  * @mask: GFP flags to use for the allocation.
1559  *
1560  * Return value: Number of page frames actually allocated
1561  */
1562 static unsigned long preallocate_image_pages(unsigned long nr_pages, gfp_t mask)
1563 {
1564         unsigned long nr_alloc = 0;
1565 
1566         while (nr_pages > 0) {
1567                 struct page *page;
1568 
1569                 page = alloc_image_page(mask);
1570                 if (!page)
1571                         break;
1572                 memory_bm_set_bit(&copy_bm, page_to_pfn(page));
1573                 if (PageHighMem(page))
1574                         alloc_highmem++;
1575                 else
1576                         alloc_normal++;
1577                 nr_pages--;
1578                 nr_alloc++;
1579         }
1580 
1581         return nr_alloc;
1582 }
1583 
1584 static unsigned long preallocate_image_memory(unsigned long nr_pages,
1585                                               unsigned long avail_normal)
1586 {
1587         unsigned long alloc;
1588 
1589         if (avail_normal <= alloc_normal)
1590                 return 0;
1591 
1592         alloc = avail_normal - alloc_normal;
1593         if (nr_pages < alloc)
1594                 alloc = nr_pages;
1595 
1596         return preallocate_image_pages(alloc, GFP_IMAGE);
1597 }
1598 
1599 #ifdef CONFIG_HIGHMEM
1600 static unsigned long preallocate_image_highmem(unsigned long nr_pages)
1601 {
1602         return preallocate_image_pages(nr_pages, GFP_IMAGE | __GFP_HIGHMEM);
1603 }
1604 
1605 /**
1606  *  __fraction - Compute (an approximation of) x * (multiplier / base).
1607  */
1608 static unsigned long __fraction(u64 x, u64 multiplier, u64 base)
1609 {
1610         return div64_u64(x * multiplier, base);
1611 }
1612 
1613 static unsigned long preallocate_highmem_fraction(unsigned long nr_pages,
1614                                                   unsigned long highmem,
1615                                                   unsigned long total)
1616 {
1617         unsigned long alloc = __fraction(nr_pages, highmem, total);
1618 
1619         return preallocate_image_pages(alloc, GFP_IMAGE | __GFP_HIGHMEM);
1620 }
1621 #else /* CONFIG_HIGHMEM */
1622 static inline unsigned long preallocate_image_highmem(unsigned long nr_pages)
1623 {
1624         return 0;
1625 }
1626 
1627 static inline unsigned long preallocate_highmem_fraction(unsigned long nr_pages,
1628                                                          unsigned long highmem,
1629                                                          unsigned long total)
1630 {
1631         return 0;
1632 }
1633 #endif /* CONFIG_HIGHMEM */
1634 
1635 /**
1636  * free_unnecessary_pages - Release preallocated pages not needed for the image.
1637  */
1638 static unsigned long free_unnecessary_pages(void)
1639 {
1640         unsigned long save, to_free_normal, to_free_highmem, free;
1641 
1642         save = count_data_pages();
1643         if (alloc_normal >= save) {
1644                 to_free_normal = alloc_normal - save;
1645                 save = 0;
1646         } else {
1647                 to_free_normal = 0;
1648                 save -= alloc_normal;
1649         }
1650         save += count_highmem_pages();
1651         if (alloc_highmem >= save) {
1652                 to_free_highmem = alloc_highmem - save;
1653         } else {
1654                 to_free_highmem = 0;
1655                 save -= alloc_highmem;
1656                 if (to_free_normal > save)
1657                         to_free_normal -= save;
1658                 else
1659                         to_free_normal = 0;
1660         }
1661         free = to_free_normal + to_free_highmem;
1662 
1663         memory_bm_position_reset(&copy_bm);
1664 
1665         while (to_free_normal > 0 || to_free_highmem > 0) {
1666                 unsigned long pfn = memory_bm_next_pfn(&copy_bm);
1667                 struct page *page = pfn_to_page(pfn);
1668 
1669                 if (PageHighMem(page)) {
1670                         if (!to_free_highmem)
1671                                 continue;
1672                         to_free_highmem--;
1673                         alloc_highmem--;
1674                 } else {
1675                         if (!to_free_normal)
1676                                 continue;
1677                         to_free_normal--;
1678                         alloc_normal--;
1679                 }
1680                 memory_bm_clear_bit(&copy_bm, pfn);
1681                 swsusp_unset_page_forbidden(page);
1682                 swsusp_unset_page_free(page);
1683                 __free_page(page);
1684         }
1685 
1686         return free;
1687 }
1688 
1689 /**
1690  * minimum_image_size - Estimate the minimum acceptable size of an image.
1691  * @saveable: Number of saveable pages in the system.
1692  *
1693  * We want to avoid attempting to free too much memory too hard, so estimate the
1694  * minimum acceptable size of a hibernation image to use as the lower limit for
1695  * preallocating memory.
1696  *
1697  * We assume that the minimum image size should be proportional to
1698  *
1699  * [number of saveable pages] - [number of pages that can be freed in theory]
1700  *
1701  * where the second term is the sum of (1) reclaimable slab pages, (2) active
1702  * and (3) inactive anonymous pages, (4) active and (5) inactive file pages.
1703  */
1704 static unsigned long minimum_image_size(unsigned long saveable)
1705 {
1706         unsigned long size;
1707 
1708         size = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B)
1709                 + global_node_page_state(NR_ACTIVE_ANON)
1710                 + global_node_page_state(NR_INACTIVE_ANON)
1711                 + global_node_page_state(NR_ACTIVE_FILE)
1712                 + global_node_page_state(NR_INACTIVE_FILE);
1713 
1714         return saveable <= size ? 0 : saveable - size;
1715 }
1716 
1717 /**
1718  * hibernate_preallocate_memory - Preallocate memory for hibernation image.
1719  *
1720  * To create a hibernation image it is necessary to make a copy of every page
1721  * frame in use.  We also need a number of page frames to be free during
1722  * hibernation for allocations made while saving the image and for device
1723  * drivers, in case they need to allocate memory from their hibernation
1724  * callbacks (these two numbers are given by PAGES_FOR_IO (which is a rough
1725  * estimate) and reserved_size divided by PAGE_SIZE (which is tunable through
1726  * /sys/power/reserved_size, respectively).  To make this happen, we compute the
1727  * total number of available page frames and allocate at least
1728  *
1729  * ([page frames total] + PAGES_FOR_IO + [metadata pages]) / 2
1730  *  + 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE)
1731  *
1732  * of them, which corresponds to the maximum size of a hibernation image.
1733  *
1734  * If image_size is set below the number following from the above formula,
1735  * the preallocation of memory is continued until the total number of saveable
1736  * pages in the system is below the requested image size or the minimum
1737  * acceptable image size returned by minimum_image_size(), whichever is greater.
1738  */
1739 int hibernate_preallocate_memory(void)
1740 {
1741         struct zone *zone;
1742         unsigned long saveable, size, max_size, count, highmem, pages = 0;
1743         unsigned long alloc, save_highmem, pages_highmem, avail_normal;
1744         ktime_t start, stop;
1745         int error;
1746 
1747         pr_info("Preallocating image memory\n");
1748         start = ktime_get();
1749 
1750         error = memory_bm_create(&orig_bm, GFP_IMAGE, PG_ANY);
1751         if (error) {
1752                 pr_err("Cannot allocate original bitmap\n");
1753                 goto err_out;
1754         }
1755 
1756         error = memory_bm_create(&copy_bm, GFP_IMAGE, PG_ANY);
1757         if (error) {
1758                 pr_err("Cannot allocate copy bitmap\n");
1759                 goto err_out;
1760         }
1761 
1762         alloc_normal = 0;
1763         alloc_highmem = 0;
1764 
1765         /* Count the number of saveable data pages. */
1766         save_highmem = count_highmem_pages();
1767         saveable = count_data_pages();
1768 
1769         /*
1770          * Compute the total number of page frames we can use (count) and the
1771          * number of pages needed for image metadata (size).
1772          */
1773         count = saveable;
1774         saveable += save_highmem;
1775         highmem = save_highmem;
1776         size = 0;
1777         for_each_populated_zone(zone) {
1778                 size += snapshot_additional_pages(zone);
1779                 if (is_highmem(zone))
1780                         highmem += zone_page_state(zone, NR_FREE_PAGES);
1781                 else
1782                         count += zone_page_state(zone, NR_FREE_PAGES);
1783         }
1784         avail_normal = count;
1785         count += highmem;
1786         count -= totalreserve_pages;
1787 
1788         /* Compute the maximum number of saveable pages to leave in memory. */
1789         max_size = (count - (size + PAGES_FOR_IO)) / 2
1790                         - 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE);
1791         /* Compute the desired number of image pages specified by image_size. */
1792         size = DIV_ROUND_UP(image_size, PAGE_SIZE);
1793         if (size > max_size)
1794                 size = max_size;
1795         /*
1796          * If the desired number of image pages is at least as large as the
1797          * current number of saveable pages in memory, allocate page frames for
1798          * the image and we're done.
1799          */
1800         if (size >= saveable) {
1801                 pages = preallocate_image_highmem(save_highmem);
1802                 pages += preallocate_image_memory(saveable - pages, avail_normal);
1803                 goto out;
1804         }
1805 
1806         /* Estimate the minimum size of the image. */
1807         pages = minimum_image_size(saveable);
1808         /*
1809          * To avoid excessive pressure on the normal zone, leave room in it to
1810          * accommodate an image of the minimum size (unless it's already too
1811          * small, in which case don't preallocate pages from it at all).
1812          */
1813         if (avail_normal > pages)
1814                 avail_normal -= pages;
1815         else
1816                 avail_normal = 0;
1817         if (size < pages)
1818                 size = min_t(unsigned long, pages, max_size);
1819 
1820         /*
1821          * Let the memory management subsystem know that we're going to need a
1822          * large number of page frames to allocate and make it free some memory.
1823          * NOTE: If this is not done, performance will be hurt badly in some
1824          * test cases.
1825          */
1826         shrink_all_memory(saveable - size);
1827 
1828         /*
1829          * The number of saveable pages in memory was too high, so apply some
1830          * pressure to decrease it.  First, make room for the largest possible
1831          * image and fail if that doesn't work.  Next, try to decrease the size
1832          * of the image as much as indicated by 'size' using allocations from
1833          * highmem and non-highmem zones separately.
1834          */
1835         pages_highmem = preallocate_image_highmem(highmem / 2);
1836         alloc = count - max_size;
1837         if (alloc > pages_highmem)
1838                 alloc -= pages_highmem;
1839         else
1840                 alloc = 0;
1841         pages = preallocate_image_memory(alloc, avail_normal);
1842         if (pages < alloc) {
1843                 /* We have exhausted non-highmem pages, try highmem. */
1844                 alloc -= pages;
1845                 pages += pages_highmem;
1846                 pages_highmem = preallocate_image_highmem(alloc);
1847                 if (pages_highmem < alloc) {
1848                         pr_err("Image allocation is %lu pages short\n",
1849                                 alloc - pages_highmem);
1850                         goto err_out;
1851                 }
1852                 pages += pages_highmem;
1853                 /*
1854                  * size is the desired number of saveable pages to leave in
1855                  * memory, so try to preallocate (all memory - size) pages.
1856                  */
1857                 alloc = (count - pages) - size;
1858                 pages += preallocate_image_highmem(alloc);
1859         } else {
1860                 /*
1861                  * There are approximately max_size saveable pages at this point
1862                  * and we want to reduce this number down to size.
1863                  */
1864                 alloc = max_size - size;
1865                 size = preallocate_highmem_fraction(alloc, highmem, count);
1866                 pages_highmem += size;
1867                 alloc -= size;
1868                 size = preallocate_image_memory(alloc, avail_normal);
1869                 pages_highmem += preallocate_image_highmem(alloc - size);
1870                 pages += pages_highmem + size;
1871         }
1872 
1873         /*
1874          * We only need as many page frames for the image as there are saveable
1875          * pages in memory, but we have allocated more.  Release the excessive
1876          * ones now.
1877          */
1878         pages -= free_unnecessary_pages();
1879 
1880  out:
1881         stop = ktime_get();
1882         pr_info("Allocated %lu pages for snapshot\n", pages);
1883         swsusp_show_speed(start, stop, pages, "Allocated");
1884 
1885         return 0;
1886 
1887  err_out:
1888         swsusp_free();
1889         return -ENOMEM;
1890 }
1891 
1892 #ifdef CONFIG_HIGHMEM
1893 /**
1894  * count_pages_for_highmem - Count non-highmem pages needed for copying highmem.
1895  *
1896  * Compute the number of non-highmem pages that will be necessary for creating
1897  * copies of highmem pages.
1898  */
1899 static unsigned int count_pages_for_highmem(unsigned int nr_highmem)
1900 {
1901         unsigned int free_highmem = count_free_highmem_pages() + alloc_highmem;
1902 
1903         if (free_highmem >= nr_highmem)
1904                 nr_highmem = 0;
1905         else
1906                 nr_highmem -= free_highmem;
1907 
1908         return nr_highmem;
1909 }
1910 #else
1911 static unsigned int count_pages_for_highmem(unsigned int nr_highmem) { return 0; }
1912 #endif /* CONFIG_HIGHMEM */
1913 
1914 /**
1915  * enough_free_mem - Check if there is enough free memory for the image.
1916  */
1917 static int enough_free_mem(unsigned int nr_pages, unsigned int nr_highmem)
1918 {
1919         struct zone *zone;
1920         unsigned int free = alloc_normal;
1921 
1922         for_each_populated_zone(zone)
1923                 if (!is_highmem(zone))
1924                         free += zone_page_state(zone, NR_FREE_PAGES);
1925 
1926         nr_pages += count_pages_for_highmem(nr_highmem);
1927         pr_debug("Normal pages needed: %u + %u, available pages: %u\n",
1928                  nr_pages, PAGES_FOR_IO, free);
1929 
1930         return free > nr_pages + PAGES_FOR_IO;
1931 }
1932 
1933 #ifdef CONFIG_HIGHMEM
1934 /**
1935  * get_highmem_buffer - Allocate a buffer for highmem pages.
1936  *
1937  * If there are some highmem pages in the hibernation image, we may need a
1938  * buffer to copy them and/or load their data.
1939  */
1940 static inline int get_highmem_buffer(int safe_needed)
1941 {
1942         buffer = get_image_page(GFP_ATOMIC, safe_needed);
1943         return buffer ? 0 : -ENOMEM;
1944 }
1945 
1946 /**
1947  * alloc_highmem_image_pages - Allocate some highmem pages for the image.
1948  *
1949  * Try to allocate as many pages as needed, but if the number of free highmem
1950  * pages is less than that, allocate them all.
1951  */
1952 static inline unsigned int alloc_highmem_pages(struct memory_bitmap *bm,
1953                                                unsigned int nr_highmem)
1954 {
1955         unsigned int to_alloc = count_free_highmem_pages();
1956 
1957         if (to_alloc > nr_highmem)
1958                 to_alloc = nr_highmem;
1959 
1960         nr_highmem -= to_alloc;
1961         while (to_alloc-- > 0) {
1962                 struct page *page;
1963 
1964                 page = alloc_image_page(__GFP_HIGHMEM|__GFP_KSWAPD_RECLAIM);
1965                 memory_bm_set_bit(bm, page_to_pfn(page));
1966         }
1967         return nr_highmem;
1968 }
1969 #else
1970 static inline int get_highmem_buffer(int safe_needed) { return 0; }
1971 
1972 static inline unsigned int alloc_highmem_pages(struct memory_bitmap *bm,
1973                                                unsigned int n) { return 0; }
1974 #endif /* CONFIG_HIGHMEM */
1975 
1976 /**
1977  * swsusp_alloc - Allocate memory for hibernation image.
1978  *
1979  * We first try to allocate as many highmem pages as there are
1980  * saveable highmem pages in the system.  If that fails, we allocate
1981  * non-highmem pages for the copies of the remaining highmem ones.
1982  *
1983  * In this approach it is likely that the copies of highmem pages will
1984  * also be located in the high memory, because of the way in which
1985  * copy_data_pages() works.
1986  */
1987 static int swsusp_alloc(struct memory_bitmap *copy_bm,
1988                         unsigned int nr_pages, unsigned int nr_highmem)
1989 {
1990         if (nr_highmem > 0) {
1991                 if (get_highmem_buffer(PG_ANY))
1992                         goto err_out;
1993                 if (nr_highmem > alloc_highmem) {
1994                         nr_highmem -= alloc_highmem;
1995                         nr_pages += alloc_highmem_pages(copy_bm, nr_highmem);
1996                 }
1997         }
1998         if (nr_pages > alloc_normal) {
1999                 nr_pages -= alloc_normal;
2000                 while (nr_pages-- > 0) {
2001                         struct page *page;
2002 
2003                         page = alloc_image_page(GFP_ATOMIC);
2004                         if (!page)
2005                                 goto err_out;
2006                         memory_bm_set_bit(copy_bm, page_to_pfn(page));
2007                 }
2008         }
2009 
2010         return 0;
2011 
2012  err_out:
2013         swsusp_free();
2014         return -ENOMEM;
2015 }
2016 
2017 asmlinkage __visible int swsusp_save(void)
2018 {
2019         unsigned int nr_pages, nr_highmem;
2020 
2021         pr_info("Creating image:\n");
2022 
2023         drain_local_pages(NULL);
2024         nr_pages = count_data_pages();
2025         nr_highmem = count_highmem_pages();
2026         pr_info("Need to copy %u pages\n", nr_pages + nr_highmem);
2027 
2028         if (!enough_free_mem(nr_pages, nr_highmem)) {
2029                 pr_err("Not enough free memory\n");
2030                 return -ENOMEM;
2031         }
2032 
2033         if (swsusp_alloc(&copy_bm, nr_pages, nr_highmem)) {
2034                 pr_err("Memory allocation failed\n");
2035                 return -ENOMEM;
2036         }
2037 
2038         /*
2039          * During allocating of suspend pagedir, new cold pages may appear.
2040          * Kill them.
2041          */
2042         drain_local_pages(NULL);
2043         copy_data_pages(&copy_bm, &orig_bm);
2044 
2045         /*
2046          * End of critical section. From now on, we can write to memory,
2047          * but we should not touch disk. This specially means we must _not_
2048          * touch swap space! Except we must write out our image of course.
2049          */
2050 
2051         nr_pages += nr_highmem;
2052         nr_copy_pages = nr_pages;
2053         nr_meta_pages = DIV_ROUND_UP(nr_pages * sizeof(long), PAGE_SIZE);
2054 
2055         pr_info("Image created (%d pages copied)\n", nr_pages);
2056 
2057         return 0;
2058 }
2059 
2060 #ifndef CONFIG_ARCH_HIBERNATION_HEADER
2061 static int init_header_complete(struct swsusp_info *info)
2062 {
2063         memcpy(&info->uts, init_utsname(), sizeof(struct new_utsname));
2064         info->version_code = LINUX_VERSION_CODE;
2065         return 0;
2066 }
2067 
2068 static const char *check_image_kernel(struct swsusp_info *info)
2069 {
2070         if (info->version_code != LINUX_VERSION_CODE)
2071                 return "kernel version";
2072         if (strcmp(info->uts.sysname,init_utsname()->sysname))
2073                 return "system type";
2074         if (strcmp(info->uts.release,init_utsname()->release))
2075                 return "kernel release";
2076         if (strcmp(info->uts.version,init_utsname()->version))
2077                 return "version";
2078         if (strcmp(info->uts.machine,init_utsname()->machine))
2079                 return "machine";
2080         return NULL;
2081 }
2082 #endif /* CONFIG_ARCH_HIBERNATION_HEADER */
2083 
2084 unsigned long snapshot_get_image_size(void)
2085 {
2086         return nr_copy_pages + nr_meta_pages + 1;
2087 }
2088 
2089 static int init_header(struct swsusp_info *info)
2090 {
2091         memset(info, 0, sizeof(struct swsusp_info));
2092         info->num_physpages = get_num_physpages();
2093         info->image_pages = nr_copy_pages;
2094         info->pages = snapshot_get_image_size();
2095         info->size = info->pages;
2096         info->size <<= PAGE_SHIFT;
2097         return init_header_complete(info);
2098 }
2099 
2100 /**
2101  * pack_pfns - Prepare PFNs for saving.
2102  * @bm: Memory bitmap.
2103  * @buf: Memory buffer to store the PFNs in.
2104  *
2105  * PFNs corresponding to set bits in @bm are stored in the area of memory
2106  * pointed to by @buf (1 page at a time).
2107  */
2108 static inline void pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
2109 {
2110         int j;
2111 
2112         for (j = 0; j < PAGE_SIZE / sizeof(long); j++) {
2113                 buf[j] = memory_bm_next_pfn(bm);
2114                 if (unlikely(buf[j] == BM_END_OF_MAP))
2115                         break;
2116         }
2117 }
2118 
2119 /**
2120  * snapshot_read_next - Get the address to read the next image page from.
2121  * @handle: Snapshot handle to be used for the reading.
2122  *
2123  * On the first call, @handle should point to a zeroed snapshot_handle
2124  * structure.  The structure gets populated then and a pointer to it should be
2125  * passed to this function every next time.
2126  *
2127  * On success, the function returns a positive number.  Then, the caller
2128  * is allowed to read up to the returned number of bytes from the memory
2129  * location computed by the data_of() macro.
2130  *
2131  * The function returns 0 to indicate the end of the data stream condition,
2132  * and negative numbers are returned on errors.  If that happens, the structure
2133  * pointed to by @handle is not updated and should not be used any more.
2134  */
2135 int snapshot_read_next(struct snapshot_handle *handle)
2136 {
2137         if (handle->cur > nr_meta_pages + nr_copy_pages)
2138                 return 0;
2139 
2140         if (!buffer) {
2141                 /* This makes the buffer be freed by swsusp_free() */
2142                 buffer = get_image_page(GFP_ATOMIC, PG_ANY);
2143                 if (!buffer)
2144                         return -ENOMEM;
2145         }
2146         if (!handle->cur) {
2147                 int error;
2148 
2149                 error = init_header((struct swsusp_info *)buffer);
2150                 if (error)
2151                         return error;
2152                 handle->buffer = buffer;
2153                 memory_bm_position_reset(&orig_bm);
2154                 memory_bm_position_reset(&copy_bm);
2155         } else if (handle->cur <= nr_meta_pages) {
2156                 clear_page(buffer);
2157                 pack_pfns(buffer, &orig_bm);
2158         } else {
2159                 struct page *page;
2160 
2161                 page = pfn_to_page(memory_bm_next_pfn(&copy_bm));
2162                 if (PageHighMem(page)) {
2163                         /*
2164                          * Highmem pages are copied to the buffer,
2165                          * because we can't return with a kmapped
2166                          * highmem page (we may not be called again).
2167                          */
2168                         void *kaddr;
2169 
2170                         kaddr = kmap_atomic(page);
2171                         copy_page(buffer, kaddr);
2172                         kunmap_atomic(kaddr);
2173                         handle->buffer = buffer;
2174                 } else {
2175                         handle->buffer = page_address(page);
2176                 }
2177         }
2178         handle->cur++;
2179         return PAGE_SIZE;
2180 }
2181 
2182 static void duplicate_memory_bitmap(struct memory_bitmap *dst,
2183                                     struct memory_bitmap *src)
2184 {
2185         unsigned long pfn;
2186 
2187         memory_bm_position_reset(src);
2188         pfn = memory_bm_next_pfn(src);
2189         while (pfn != BM_END_OF_MAP) {
2190                 memory_bm_set_bit(dst, pfn);
2191                 pfn = memory_bm_next_pfn(src);
2192         }
2193 }
2194 
2195 /**
2196  * mark_unsafe_pages - Mark pages that were used before hibernation.
2197  *
2198  * Mark the pages that cannot be used for storing the image during restoration,
2199  * because they conflict with the pages that had been used before hibernation.
2200  */
2201 static void mark_unsafe_pages(struct memory_bitmap *bm)
2202 {
2203         unsigned long pfn;
2204 
2205         /* Clear the "free"/"unsafe" bit for all PFNs */
2206         memory_bm_position_reset(free_pages_map);
2207         pfn = memory_bm_next_pfn(free_pages_map);
2208         while (pfn != BM_END_OF_MAP) {
2209                 memory_bm_clear_current(free_pages_map);
2210                 pfn = memory_bm_next_pfn(free_pages_map);
2211         }
2212 
2213         /* Mark pages that correspond to the "original" PFNs as "unsafe" */
2214         duplicate_memory_bitmap(free_pages_map, bm);
2215 
2216         allocated_unsafe_pages = 0;
2217 }
2218 
2219 static int check_header(struct swsusp_info *info)
2220 {
2221         const char *reason;
2222 
2223         reason = check_image_kernel(info);
2224         if (!reason && info->num_physpages != get_num_physpages())
2225                 reason = "memory size";
2226         if (reason) {
2227                 pr_err("Image mismatch: %s\n", reason);
2228                 return -EPERM;
2229         }
2230         return 0;
2231 }
2232 
2233 /**
2234  * load header - Check the image header and copy the data from it.
2235  */
2236 static int load_header(struct swsusp_info *info)
2237 {
2238         int error;
2239 
2240         restore_pblist = NULL;
2241         error = check_header(info);
2242         if (!error) {
2243                 nr_copy_pages = info->image_pages;
2244                 nr_meta_pages = info->pages - info->image_pages - 1;
2245         }
2246         return error;
2247 }
2248 
2249 /**
2250  * unpack_orig_pfns - Set bits corresponding to given PFNs in a memory bitmap.
2251  * @bm: Memory bitmap.
2252  * @buf: Area of memory containing the PFNs.
2253  *
2254  * For each element of the array pointed to by @buf (1 page at a time), set the
2255  * corresponding bit in @bm.
2256  */
2257 static int unpack_orig_pfns(unsigned long *buf, struct memory_bitmap *bm)
2258 {
2259         int j;
2260 
2261         for (j = 0; j < PAGE_SIZE / sizeof(long); j++) {
2262                 if (unlikely(buf[j] == BM_END_OF_MAP))
2263                         break;
2264 
2265                 if (pfn_valid(buf[j]) && memory_bm_pfn_present(bm, buf[j]))
2266                         memory_bm_set_bit(bm, buf[j]);
2267                 else
2268                         return -EFAULT;
2269         }
2270 
2271         return 0;
2272 }
2273 
2274 #ifdef CONFIG_HIGHMEM
2275 /*
2276  * struct highmem_pbe is used for creating the list of highmem pages that
2277  * should be restored atomically during the resume from disk, because the page
2278  * frames they have occupied before the suspend are in use.
2279  */
2280 struct highmem_pbe {
2281         struct page *copy_page; /* data is here now */
2282         struct page *orig_page; /* data was here before the suspend */
2283         struct highmem_pbe *next;
2284 };
2285 
2286 /*
2287  * List of highmem PBEs needed for restoring the highmem pages that were
2288  * allocated before the suspend and included in the suspend image, but have
2289  * also been allocated by the "resume" kernel, so their contents cannot be
2290  * written directly to their "original" page frames.
2291  */
2292 static struct highmem_pbe *highmem_pblist;
2293 
2294 /**
2295  * count_highmem_image_pages - Compute the number of highmem pages in the image.
2296  * @bm: Memory bitmap.
2297  *
2298  * The bits in @bm that correspond to image pages are assumed to be set.
2299  */
2300 static unsigned int count_highmem_image_pages(struct memory_bitmap *bm)
2301 {
2302         unsigned long pfn;
2303         unsigned int cnt = 0;
2304 
2305         memory_bm_position_reset(bm);
2306         pfn = memory_bm_next_pfn(bm);
2307         while (pfn != BM_END_OF_MAP) {
2308                 if (PageHighMem(pfn_to_page(pfn)))
2309                         cnt++;
2310 
2311                 pfn = memory_bm_next_pfn(bm);
2312         }
2313         return cnt;
2314 }
2315 
2316 static unsigned int safe_highmem_pages;
2317 
2318 static struct memory_bitmap *safe_highmem_bm;
2319 
2320 /**
2321  * prepare_highmem_image - Allocate memory for loading highmem data from image.
2322  * @bm: Pointer to an uninitialized memory bitmap structure.
2323  * @nr_highmem_p: Pointer to the number of highmem image pages.
2324  *
2325  * Try to allocate as many highmem pages as there are highmem image pages
2326  * (@nr_highmem_p points to the variable containing the number of highmem image
2327  * pages).  The pages that are "safe" (ie. will not be overwritten when the
2328  * hibernation image is restored entirely) have the corresponding bits set in
2329  * @bm (it must be unitialized).
2330  *
2331  * NOTE: This function should not be called if there are no highmem image pages.
2332  */
2333 static int prepare_highmem_image(struct memory_bitmap *bm,
2334                                  unsigned int *nr_highmem_p)
2335 {
2336         unsigned int to_alloc;
2337 
2338         if (memory_bm_create(bm, GFP_ATOMIC, PG_SAFE))
2339                 return -ENOMEM;
2340 
2341         if (get_highmem_buffer(PG_SAFE))
2342                 return -ENOMEM;
2343 
2344         to_alloc = count_free_highmem_pages();
2345         if (to_alloc > *nr_highmem_p)
2346                 to_alloc = *nr_highmem_p;
2347         else
2348                 *nr_highmem_p = to_alloc;
2349 
2350         safe_highmem_pages = 0;
2351         while (to_alloc-- > 0) {
2352                 struct page *page;
2353 
2354                 page = alloc_page(__GFP_HIGHMEM);
2355                 if (!swsusp_page_is_free(page)) {
2356                         /* The page is "safe", set its bit the bitmap */
2357                         memory_bm_set_bit(bm, page_to_pfn(page));
2358                         safe_highmem_pages++;
2359                 }
2360                 /* Mark the page as allocated */
2361                 swsusp_set_page_forbidden(page);
2362                 swsusp_set_page_free(page);
2363         }
2364         memory_bm_position_reset(bm);
2365         safe_highmem_bm = bm;
2366         return 0;
2367 }
2368 
2369 static struct page *last_highmem_page;
2370 
2371 /**
2372  * get_highmem_page_buffer - Prepare a buffer to store a highmem image page.
2373  *
2374  * For a given highmem image page get a buffer that suspend_write_next() should
2375  * return to its caller to write to.
2376  *
2377  * If the page is to be saved to its "original" page frame or a copy of
2378  * the page is to be made in the highmem, @buffer is returned.  Otherwise,
2379  * the copy of the page is to be made in normal memory, so the address of
2380  * the copy is returned.
2381  *
2382  * If @buffer is returned, the caller of suspend_write_next() will write
2383  * the page's contents to @buffer, so they will have to be copied to the
2384  * right location on the next call to suspend_write_next() and it is done
2385  * with the help of copy_last_highmem_page().  For this purpose, if
2386  * @buffer is returned, @last_highmem_page is set to the page to which
2387  * the data will have to be copied from @buffer.
2388  */
2389 static void *get_highmem_page_buffer(struct page *page,
2390                                      struct chain_allocator *ca)
2391 {
2392         struct highmem_pbe *pbe;
2393         void *kaddr;
2394 
2395         if (swsusp_page_is_forbidden(page) && swsusp_page_is_free(page)) {
2396                 /*
2397                  * We have allocated the "original" page frame and we can
2398                  * use it directly to store the loaded page.
2399                  */
2400                 last_highmem_page = page;
2401                 return buffer;
2402         }
2403         /*
2404          * The "original" page frame has not been allocated and we have to
2405          * use a "safe" page frame to store the loaded page.
2406          */
2407         pbe = chain_alloc(ca, sizeof(struct highmem_pbe));
2408         if (!pbe) {
2409                 swsusp_free();
2410                 return ERR_PTR(-ENOMEM);
2411         }
2412         pbe->orig_page = page;
2413         if (safe_highmem_pages > 0) {
2414                 struct page *tmp;
2415 
2416                 /* Copy of the page will be stored in high memory */
2417                 kaddr = buffer;
2418                 tmp = pfn_to_page(memory_bm_next_pfn(safe_highmem_bm));
2419                 safe_highmem_pages--;
2420                 last_highmem_page = tmp;
2421                 pbe->copy_page = tmp;
2422         } else {
2423                 /* Copy of the page will be stored in normal memory */
2424                 kaddr = safe_pages_list;
2425                 safe_pages_list = safe_pages_list->next;
2426                 pbe->copy_page = virt_to_page(kaddr);
2427         }
2428         pbe->next = highmem_pblist;
2429         highmem_pblist = pbe;
2430         return kaddr;
2431 }
2432 
2433 /**
2434  * copy_last_highmem_page - Copy most the most recent highmem image page.
2435  *
2436  * Copy the contents of a highmem image from @buffer, where the caller of
2437  * snapshot_write_next() has stored them, to the right location represented by
2438  * @last_highmem_page .
2439  */
2440 static void copy_last_highmem_page(void)
2441 {
2442         if (last_highmem_page) {
2443                 void *dst;
2444 
2445                 dst = kmap_atomic(last_highmem_page);
2446                 copy_page(dst, buffer);
2447                 kunmap_atomic(dst);
2448                 last_highmem_page = NULL;
2449         }
2450 }
2451 
2452 static inline int last_highmem_page_copied(void)
2453 {
2454         return !last_highmem_page;
2455 }
2456 
2457 static inline void free_highmem_data(void)
2458 {
2459         if (safe_highmem_bm)
2460                 memory_bm_free(safe_highmem_bm, PG_UNSAFE_CLEAR);
2461 
2462         if (buffer)
2463                 free_image_page(buffer, PG_UNSAFE_CLEAR);
2464 }
2465 #else
2466 static unsigned int count_highmem_image_pages(struct memory_bitmap *bm) { return 0; }
2467 
2468 static inline int prepare_highmem_image(struct memory_bitmap *bm,
2469                                         unsigned int *nr_highmem_p) { return 0; }
2470 
2471 static inline void *get_highmem_page_buffer(struct page *page,
2472                                             struct chain_allocator *ca)
2473 {
2474         return ERR_PTR(-EINVAL);
2475 }
2476 
2477 static inline void copy_last_highmem_page(void) {}
2478 static inline int last_highmem_page_copied(void) { return 1; }
2479 static inline void free_highmem_data(void) {}
2480 #endif /* CONFIG_HIGHMEM */
2481 
2482 #define PBES_PER_LINKED_PAGE    (LINKED_PAGE_DATA_SIZE / sizeof(struct pbe))
2483 
2484 /**
2485  * prepare_image - Make room for loading hibernation image.
2486  * @new_bm: Unitialized memory bitmap structure.
2487  * @bm: Memory bitmap with unsafe pages marked.
2488  *
2489  * Use @bm to mark the pages that will be overwritten in the process of
2490  * restoring the system memory state from the suspend image ("unsafe" pages)
2491  * and allocate memory for the image.
2492  *
2493  * The idea is to allocate a new memory bitmap first and then allocate
2494  * as many pages as needed for image data, but without specifying what those
2495  * pages will be used for just yet.  Instead, we mark them all as allocated and
2496  * create a lists of "safe" pages to be used later.  On systems with high
2497  * memory a list of "safe" highmem pages is created too.
2498  */
2499 static int prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
2500 {
2501         unsigned int nr_pages, nr_highmem;
2502         struct linked_page *lp;
2503         int error;
2504 
2505         /* If there is no highmem, the buffer will not be necessary */
2506         free_image_page(buffer, PG_UNSAFE_CLEAR);
2507         buffer = NULL;
2508 
2509         nr_highmem = count_highmem_image_pages(bm);
2510         mark_unsafe_pages(bm);
2511 
2512         error = memory_bm_create(new_bm, GFP_ATOMIC, PG_SAFE);
2513         if (error)
2514                 goto Free;
2515 
2516         duplicate_memory_bitmap(new_bm, bm);
2517         memory_bm_free(bm, PG_UNSAFE_KEEP);
2518         if (nr_highmem > 0) {
2519                 error = prepare_highmem_image(bm, &nr_highmem);
2520                 if (error)
2521                         goto Free;
2522         }
2523         /*
2524          * Reserve some safe pages for potential later use.
2525          *
2526          * NOTE: This way we make sure there will be enough safe pages for the
2527          * chain_alloc() in get_buffer().  It is a bit wasteful, but
2528          * nr_copy_pages cannot be greater than 50% of the memory anyway.
2529          *
2530          * nr_copy_pages cannot be less than allocated_unsafe_pages too.
2531          */
2532         nr_pages = nr_copy_pages - nr_highmem - allocated_unsafe_pages;
2533         nr_pages = DIV_ROUND_UP(nr_pages, PBES_PER_LINKED_PAGE);
2534         while (nr_pages > 0) {
2535                 lp = get_image_page(GFP_ATOMIC, PG_SAFE);
2536                 if (!lp) {
2537                         error = -ENOMEM;
2538                         goto Free;
2539                 }
2540                 lp->next = safe_pages_list;
2541                 safe_pages_list = lp;
2542                 nr_pages--;
2543         }
2544         /* Preallocate memory for the image */
2545         nr_pages = nr_copy_pages - nr_highmem - allocated_unsafe_pages;
2546         while (nr_pages > 0) {
2547                 lp = (struct linked_page *)get_zeroed_page(GFP_ATOMIC);
2548                 if (!lp) {
2549                         error = -ENOMEM;
2550                         goto Free;
2551                 }
2552                 if (!swsusp_page_is_free(virt_to_page(lp))) {
2553                         /* The page is "safe", add it to the list */
2554                         lp->next = safe_pages_list;
2555                         safe_pages_list = lp;
2556                 }
2557                 /* Mark the page as allocated */
2558                 swsusp_set_page_forbidden(virt_to_page(lp));
2559                 swsusp_set_page_free(virt_to_page(lp));
2560                 nr_pages--;
2561         }
2562         return 0;
2563 
2564  Free:
2565         swsusp_free();
2566         return error;
2567 }
2568 
2569 /**
2570  * get_buffer - Get the address to store the next image data page.
2571  *
2572  * Get the address that snapshot_write_next() should return to its caller to
2573  * write to.
2574  */
2575 static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
2576 {
2577         struct pbe *pbe;
2578         struct page *page;
2579         unsigned long pfn = memory_bm_next_pfn(bm);
2580 
2581         if (pfn == BM_END_OF_MAP)
2582                 return ERR_PTR(-EFAULT);
2583 
2584         page = pfn_to_page(pfn);
2585         if (PageHighMem(page))
2586                 return get_highmem_page_buffer(page, ca);
2587 
2588         if (swsusp_page_is_forbidden(page) && swsusp_page_is_free(page))
2589                 /*
2590                  * We have allocated the "original" page frame and we can
2591                  * use it directly to store the loaded page.
2592                  */
2593                 return page_address(page);
2594 
2595         /*
2596          * The "original" page frame has not been allocated and we have to
2597          * use a "safe" page frame to store the loaded page.
2598          */
2599         pbe = chain_alloc(ca, sizeof(struct pbe));
2600         if (!pbe) {
2601                 swsusp_free();
2602                 return ERR_PTR(-ENOMEM);
2603         }
2604         pbe->orig_address = page_address(page);
2605         pbe->address = safe_pages_list;
2606         safe_pages_list = safe_pages_list->next;
2607         pbe->next = restore_pblist;
2608         restore_pblist = pbe;
2609         return pbe->address;
2610 }
2611 
2612 /**
2613  * snapshot_write_next - Get the address to store the next image page.
2614  * @handle: Snapshot handle structure to guide the writing.
2615  *
2616  * On the first call, @handle should point to a zeroed snapshot_handle
2617  * structure.  The structure gets populated then and a pointer to it should be
2618  * passed to this function every next time.
2619  *
2620  * On success, the function returns a positive number.  Then, the caller
2621  * is allowed to write up to the returned number of bytes to the memory
2622  * location computed by the data_of() macro.
2623  *
2624  * The function returns 0 to indicate the "end of file" condition.  Negative
2625  * numbers are returned on errors, in which cases the structure pointed to by
2626  * @handle is not updated and should not be used any more.
2627  */
2628 int snapshot_write_next(struct snapshot_handle *handle)
2629 {
2630         static struct chain_allocator ca;
2631         int error = 0;
2632 
2633         /* Check if we have already loaded the entire image */
2634         if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages)
2635                 return 0;
2636 
2637         handle->sync_read = 1;
2638 
2639         if (!handle->cur) {
2640                 if (!buffer)
2641                         /* This makes the buffer be freed by swsusp_free() */
2642                         buffer = get_image_page(GFP_ATOMIC, PG_ANY);
2643 
2644                 if (!buffer)
2645                         return -ENOMEM;
2646 
2647                 handle->buffer = buffer;
2648         } else if (handle->cur == 1) {
2649                 error = load_header(buffer);
2650                 if (error)
2651                         return error;
2652 
2653                 safe_pages_list = NULL;
2654 
2655                 error = memory_bm_create(&copy_bm, GFP_ATOMIC, PG_ANY);
2656                 if (error)
2657                         return error;
2658 
2659                 hibernate_restore_protection_begin();
2660         } else if (handle->cur <= nr_meta_pages + 1) {
2661                 error = unpack_orig_pfns(buffer, &copy_bm);
2662                 if (error)
2663                         return error;
2664 
2665                 if (handle->cur == nr_meta_pages + 1) {
2666                         error = prepare_image(&orig_bm, &copy_bm);
2667                         if (error)
2668                                 return error;
2669 
2670                         chain_init(&ca, GFP_ATOMIC, PG_SAFE);
2671                         memory_bm_position_reset(&orig_bm);
2672                         restore_pblist = NULL;
2673                         handle->buffer = get_buffer(&orig_bm, &ca);
2674                         handle->sync_read = 0;
2675                         if (IS_ERR(handle->buffer))
2676                                 return PTR_ERR(handle->buffer);
2677                 }
2678         } else {
2679                 copy_last_highmem_page();
2680                 hibernate_restore_protect_page(handle->buffer);
2681                 handle->buffer = get_buffer(&orig_bm, &ca);
2682                 if (IS_ERR(handle->buffer))
2683                         return PTR_ERR(handle->buffer);
2684                 if (handle->buffer != buffer)
2685                         handle->sync_read = 0;
2686         }
2687         handle->cur++;
2688         return PAGE_SIZE;
2689 }
2690 
2691 /**
2692  * snapshot_write_finalize - Complete the loading of a hibernation image.
2693  *
2694  * Must be called after the last call to snapshot_write_next() in case the last
2695  * page in the image happens to be a highmem page and its contents should be
2696  * stored in highmem.  Additionally, it recycles bitmap memory that's not
2697  * necessary any more.
2698  */
2699 void snapshot_write_finalize(struct snapshot_handle *handle)
2700 {
2701         copy_last_highmem_page();
2702         hibernate_restore_protect_page(handle->buffer);
2703         /* Do that only if we have loaded the image entirely */
2704         if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages) {
2705                 memory_bm_recycle(&orig_bm);
2706                 free_highmem_data();
2707         }
2708 }
2709 
2710 int snapshot_image_loaded(struct snapshot_handle *handle)
2711 {
2712         return !(!nr_copy_pages || !last_highmem_page_copied() ||
2713                         handle->cur <= nr_meta_pages + nr_copy_pages);
2714 }
2715 
2716 #ifdef CONFIG_HIGHMEM
2717 /* Assumes that @buf is ready and points to a "safe" page */
2718 static inline void swap_two_pages_data(struct page *p1, struct page *p2,
2719                                        void *buf)
2720 {
2721         void *kaddr1, *kaddr2;
2722 
2723         kaddr1 = kmap_atomic(p1);
2724         kaddr2 = kmap_atomic(p2);
2725         copy_page(buf, kaddr1);
2726         copy_page(kaddr1, kaddr2);
2727         copy_page(kaddr2, buf);
2728         kunmap_atomic(kaddr2);
2729         kunmap_atomic(kaddr1);
2730 }
2731 
2732 /**
2733  * restore_highmem - Put highmem image pages into their original locations.
2734  *
2735  * For each highmem page that was in use before hibernation and is included in
2736  * the image, and also has been allocated by the "restore" kernel, swap its
2737  * current contents with the previous (ie. "before hibernation") ones.
2738  *
2739  * If the restore eventually fails, we can call this function once again and
2740  * restore the highmem state as seen by the restore kernel.
2741  */
2742 int restore_highmem(void)
2743 {
2744         struct highmem_pbe *pbe = highmem_pblist;
2745         void *buf;
2746 
2747         if (!pbe)
2748                 return 0;
2749 
2750         buf = get_image_page(GFP_ATOMIC, PG_SAFE);
2751         if (!buf)
2752                 return -ENOMEM;
2753 
2754         while (pbe) {
2755                 swap_two_pages_data(pbe->copy_page, pbe->orig_page, buf);
2756                 pbe = pbe->next;
2757         }
2758         free_image_page(buf, PG_UNSAFE_CLEAR);
2759         return 0;
2760 }
2761 #endif /* CONFIG_HIGHMEM */
2762 

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