kernel/power/snapshot.c

   1 /*
   2  * linux/kernel/power/snapshot.c
   3  *
   4  * This file provide system snapshot/restore functionality.
   5  *
   6  * Copyright (C) 1998-2005 Pavel Machek <pavel@suse.cz>
   7  *
   8  * This file is released under the GPLv2, and is based on swsusp.c.
   9  *
  10  */
  11
  12
  13 #include <linux/version.h>
  14 #include <linux/module.h>
  15 #include <linux/mm.h>
  16 #include <linux/suspend.h>
  17 #include <linux/smp_lock.h>
  18 #include <linux/delay.h>
  19 #include <linux/bitops.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/kernel.h>
  22 #include <linux/pm.h>
  23 #include <linux/device.h>
  24 #include <linux/bootmem.h>
  25 #include <linux/syscalls.h>
  26 #include <linux/console.h>
  27 #include <linux/highmem.h>
  28
  29 #include <asm/uaccess.h>
  30 #include <asm/mmu_context.h>
  31 #include <asm/pgtable.h>
  32 #include <asm/tlbflush.h>
  33 #include <asm/io.h>
  34
  35 #include "power.h"
  36
  37 struct pbe *pagedir_nosave;
  38 static unsigned int nr_copy_pages;
  39 static unsigned int nr_meta_pages;
  40 static unsigned long *buffer;
  41
  42 #ifdef CONFIG_HIGHMEM
  43 unsigned int count_highmem_pages(void)
  44 {
  45         struct zone *zone;
  46         unsigned long zone_pfn;
  47         unsigned int n = 0;
  48
  49         for_each_zone (zone)
  50                 if (is_highmem(zone)) {
  51                         mark_free_pages(zone);
  52                         for (zone_pfn = 0; zone_pfn < zone->spanned_pages; zone_pfn++) {
  53                                 struct page *page;
  54                                 unsigned long pfn = zone_pfn + zone->zone_start_pfn;
  55                                 if (!pfn_valid(pfn))
  56                                         continue;
  57                                 page = pfn_to_page(pfn);
  58                                 if (PageReserved(page))
  59                                         continue;
  60                                 if (PageNosaveFree(page))
  61                                         continue;
  62                                 n++;
  63                         }
  64                 }
  65         return n;
  66 }
  67
  68 struct highmem_page {
  69         char *data;
  70         struct page *page;
  71         struct highmem_page *next;
  72 };
  73
  74 static struct highmem_page *highmem_copy;
  75
  76 static int save_highmem_zone(struct zone *zone)
  77 {
  78         unsigned long zone_pfn;
  79         mark_free_pages(zone);
  80         for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
  81                 struct page *page;
  82                 struct highmem_page *save;
  83                 void *kaddr;
  84                 unsigned long pfn = zone_pfn + zone->zone_start_pfn;
  85
  86                 if (!(pfn%10000))
  87                         printk(".");
  88                 if (!pfn_valid(pfn))
  89                         continue;
  90                 page = pfn_to_page(pfn);
  91                 /*
  92                  * This condition results from rvmalloc() sans vmalloc_32()
  93                  * and architectural memory reservations. This should be
  94                  * corrected eventually when the cases giving rise to this
  95                  * are better understood.
  96                  */
  97                 if (PageReserved(page))
  98                         continue;
  99                 BUG_ON(PageNosave(page));
 100                 if (PageNosaveFree(page))
 101                         continue;
 102                 save = kmalloc(sizeof(struct highmem_page), GFP_ATOMIC);
 103                 if (!save)
 104                         return -ENOMEM;
 105                 save->next = highmem_copy;
 106                 save->page = page;
 107                 save->data = (void *) get_zeroed_page(GFP_ATOMIC);
 108                 if (!save->data) {
 109                         kfree(save);
 110                         return -ENOMEM;
 111                 }
 112                 kaddr = kmap_atomic(page, KM_USER0);
 113                 memcpy(save->data, kaddr, PAGE_SIZE);
 114                 kunmap_atomic(kaddr, KM_USER0);
 115                 highmem_copy = save;
 116         }
 117         return 0;
 118 }
 119
 120 int save_highmem(void)
 121 {
 122         struct zone *zone;
 123         int res = 0;
 124
 125         pr_debug("swsusp: Saving Highmem");
 126         drain_local_pages();
 127         for_each_zone (zone) {
 128                 if (is_highmem(zone))
 129                         res = save_highmem_zone(zone);
 130                 if (res)
 131                         return res;
 132         }
 133         printk("\n");
 134         return 0;
 135 }
 136
 137 int restore_highmem(void)
 138 {
 139         printk("swsusp: Restoring Highmem\n");
 140         while (highmem_copy) {
 141                 struct highmem_page *save = highmem_copy;
 142                 void *kaddr;
 143                 highmem_copy = save->next;
 144
 145                 kaddr = kmap_atomic(save->page, KM_USER0);
 146                 memcpy(kaddr, save->data, PAGE_SIZE);
 147                 kunmap_atomic(kaddr, KM_USER0);
 148                 free_page((long) save->data);
 149                 kfree(save);
 150         }
 151         return 0;
 152 }
 153 #endif
 154
 155 static int pfn_is_nosave(unsigned long pfn)
 156 {
 157         unsigned long nosave_begin_pfn = __pa(&__nosave_begin) >> PAGE_SHIFT;
 158         unsigned long nosave_end_pfn = PAGE_ALIGN(__pa(&__nosave_end)) >> PAGE_SHIFT;
 159         return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
 160 }
 161
 162 /**
 163  *      saveable - Determine whether a page should be cloned or not.
 164  *      @pfn:   The page
 165  *
 166  *      We save a page if it's Reserved, and not in the range of pages
 167  *      statically defined as 'unsaveable', or if it isn't reserved, and
 168  *      isn't part of a free chunk of pages.
 169  */
 170
 171 static int saveable(struct zone *zone, unsigned long *zone_pfn)
 172 {
 173         unsigned long pfn = *zone_pfn + zone->zone_start_pfn;
 174         struct page *page;
 175
 176         if (!pfn_valid(pfn))
 177                 return 0;
 178
 179         page = pfn_to_page(pfn);
 180         BUG_ON(PageReserved(page) && PageNosave(page));
 181         if (PageNosave(page))
 182                 return 0;
 183         if (PageReserved(page) && pfn_is_nosave(pfn))
 184                 return 0;
 185         if (PageNosaveFree(page))
 186                 return 0;
 187
 188         return 1;
 189 }
 190
 191 unsigned int count_data_pages(void)
 192 {
 193         struct zone *zone;
 194         unsigned long zone_pfn;
 195         unsigned int n = 0;
 196
 197         for_each_zone (zone) {
 198                 if (is_highmem(zone))
 199                         continue;
 200                 mark_free_pages(zone);
 201                 for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
 202                         n += saveable(zone, &zone_pfn);
 203         }
 204         return n;
 205 }
 206
 207 static void copy_data_pages(struct pbe *pblist)
 208 {
 209         struct zone *zone;
 210         unsigned long zone_pfn;
 211         struct pbe *pbe, *p;
 212
 213         pbe = pblist;
 214         for_each_zone (zone) {
 215                 if (is_highmem(zone))
 216                         continue;
 217                 mark_free_pages(zone);
 218                 /* This is necessary for swsusp_free() */
 219                 for_each_pb_page (p, pblist)
 220                         SetPageNosaveFree(virt_to_page(p));
 221                 for_each_pbe (p, pblist)
 222                         SetPageNosaveFree(virt_to_page(p->address));
 223                 for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
 224                         if (saveable(zone, &zone_pfn)) {
 225                                 struct page *page;
 226                                 page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
 227                                 BUG_ON(!pbe);
 228                                 pbe->orig_address = (unsigned long)page_address(page);
 229                                 /* copy_page is not usable for copying task structs. */
 230                                 memcpy((void *)pbe->address, (void *)pbe->orig_address, PAGE_SIZE);
 231                                 pbe = pbe->next;
 232                         }
 233                 }
 234         }
 235         BUG_ON(pbe);
 236 }
 237
 238
 239 /**
 240  *      free_pagedir - free pages allocated with alloc_pagedir()
 241  */
 242
 243 static void free_pagedir(struct pbe *pblist)
 244 {
 245         struct pbe *pbe;
 246
 247         while (pblist) {
 248                 pbe = (pblist + PB_PAGE_SKIP)->next;
 249                 ClearPageNosave(virt_to_page(pblist));
 250                 ClearPageNosaveFree(virt_to_page(pblist));
 251                 free_page((unsigned long)pblist);
 252                 pblist = pbe;
 253         }
 254 }
 255
 256 /**
 257  *      fill_pb_page - Create a list of PBEs on a given memory page
 258  */
 259
 260 static inline void fill_pb_page(struct pbe *pbpage)
 261 {
 262         struct pbe *p;
 263
 264         p = pbpage;
 265         pbpage += PB_PAGE_SKIP;
 266         do
 267                 p->next = p + 1;
 268         while (++p < pbpage);
 269 }
 270
 271 /**
 272  *      create_pbe_list - Create a list of PBEs on top of a given chain
 273  *      of memory pages allocated with alloc_pagedir()
 274  */
 275
 276 static inline void create_pbe_list(struct pbe *pblist, unsigned int nr_pages)
 277 {
 278         struct pbe *pbpage, *p;
 279         unsigned int num = PBES_PER_PAGE;
 280
 281         for_each_pb_page (pbpage, pblist) {
 282                 if (num >= nr_pages)
 283                         break;
 284
 285                 fill_pb_page(pbpage);
 286                 num += PBES_PER_PAGE;
 287         }
 288         if (pbpage) {
 289                 for (num -= PBES_PER_PAGE - 1, p = pbpage; num < nr_pages; p++, num++)
 290                         p->next = p + 1;
 291                 p->next = NULL;
 292         }
 293 }
 294
 295 /**
 296  *      On resume it is necessary to trace and eventually free the unsafe
 297  *      pages that have been allocated, because they are needed for I/O
 298  *      (on x86-64 we likely will "eat" these pages once again while
 299  *      creating the temporary page translation tables)
 300  */
 301
 302 struct eaten_page {
 303         struct eaten_page *next;
 304         char padding[PAGE_SIZE - sizeof(void *)];
 305 };
 306
 307 static struct eaten_page *eaten_pages = NULL;
 308
 309 static void release_eaten_pages(void)
 310 {
 311         struct eaten_page *p, *q;
 312
 313         p = eaten_pages;
 314         while (p) {
 315                 q = p->next;
 316                 /* We don't want swsusp_free() to free this page again */
 317                 ClearPageNosave(virt_to_page(p));
 318                 free_page((unsigned long)p);
 319                 p = q;
 320         }
 321         eaten_pages = NULL;
 322 }
 323
 324 /**
 325  *      @safe_needed - on resume, for storing the PBE list and the image,
 326  *      we can only use memory pages that do not conflict with the pages
 327  *      which had been used before suspend.
 328  *
 329  *      The unsafe pages are marked with the PG_nosave_free flag
 330  *
 331  *      Allocated but unusable (ie eaten) memory pages should be marked
 332  *      so that swsusp_free() can release them
 333  */
 334
 335 static inline void *alloc_image_page(gfp_t gfp_mask, int safe_needed)
 336 {
 337         void *res;
 338
 339         if (safe_needed)
 340                 do {
 341                         res = (void *)get_zeroed_page(gfp_mask);
 342                         if (res && PageNosaveFree(virt_to_page(res))) {
 343                                 /* This is for swsusp_free() */
 344                                 SetPageNosave(virt_to_page(res));
 345                                 ((struct eaten_page *)res)->next = eaten_pages;
 346                                 eaten_pages = res;
 347                         }
 348                 } while (res && PageNosaveFree(virt_to_page(res)));
 349         else
 350                 res = (void *)get_zeroed_page(gfp_mask);
 351         if (res) {
 352                 SetPageNosave(virt_to_page(res));
 353                 SetPageNosaveFree(virt_to_page(res));
 354         }
 355         return res;
 356 }
 357
 358 unsigned long get_safe_page(gfp_t gfp_mask)
 359 {
 360         return (unsigned long)alloc_image_page(gfp_mask, 1);
 361 }
 362
 363 /**
 364  *      alloc_pagedir - Allocate the page directory.
 365  *
 366  *      First, determine exactly how many pages we need and
 367  *      allocate them.
 368  *
 369  *      We arrange the pages in a chain: each page is an array of PBES_PER_PAGE
 370  *      struct pbe elements (pbes) and the last element in the page points
 371  *      to the next page.
 372  *
 373  *      On each page we set up a list of struct_pbe elements.
 374  */
 375
 376 struct pbe *alloc_pagedir(unsigned int nr_pages, gfp_t gfp_mask, int safe_needed)
 377 {
 378         unsigned int num;
 379         struct pbe *pblist, *pbe;
 380
 381         if (!nr_pages)
 382                 return NULL;
 383
 384         pblist = alloc_image_page(gfp_mask, safe_needed);
 385         /* FIXME: rewrite this ugly loop */
 386         for (pbe = pblist, num = PBES_PER_PAGE; pbe && num < nr_pages;
 387                         pbe = pbe->next, num += PBES_PER_PAGE) {
 388                 pbe += PB_PAGE_SKIP;
 389                 pbe->next = alloc_image_page(gfp_mask, safe_needed);
 390         }
 391         if (!pbe) { /* get_zeroed_page() failed */
 392                 free_pagedir(pblist);
 393                 pblist = NULL;
 394         } else
 395                 create_pbe_list(pblist, nr_pages);
 396         return pblist;
 397 }
 398
 399 /**
 400  * Free pages we allocated for suspend. Suspend pages are alocated
 401  * before atomic copy, so we need to free them after resume.
 402  */
 403
 404 void swsusp_free(void)
 405 {
 406         struct zone *zone;
 407         unsigned long zone_pfn;
 408
 409         for_each_zone(zone) {
 410                 for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
 411                         if (pfn_valid(zone_pfn + zone->zone_start_pfn)) {
 412                                 struct page *page;
 413                                 page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
 414                                 if (PageNosave(page) && PageNosaveFree(page)) {
 415                                         ClearPageNosave(page);
 416                                         ClearPageNosaveFree(page);
 417                                         free_page((long) page_address(page));
 418                                 }
 419                         }
 420         }
 421         nr_copy_pages = 0;
 422         nr_meta_pages = 0;
 423         pagedir_nosave = NULL;
 424         buffer = NULL;
 425 }
 426
 427
 428 /**
 429  *      enough_free_mem - Make sure we enough free memory to snapshot.
 430  *
 431  *      Returns TRUE or FALSE after checking the number of available
 432  *      free pages.
 433  */
 434
 435 static int enough_free_mem(unsigned int nr_pages)
 436 {
 437         struct zone *zone;
 438         unsigned int n = 0;
 439
 440         for_each_zone (zone)
 441                 if (!is_highmem(zone))
 442                         n += zone->free_pages;
 443         pr_debug("swsusp: available memory: %u pages\n", n);
 444         return n > (nr_pages + PAGES_FOR_IO +
 445                 (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
 446 }
 447
 448 static int alloc_data_pages(struct pbe *pblist, gfp_t gfp_mask, int safe_needed)
 449 {
 450         struct pbe *p;
 451
 452         for_each_pbe (p, pblist) {
 453                 p->address = (unsigned long)alloc_image_page(gfp_mask, safe_needed);
 454                 if (!p->address)
 455                         return -ENOMEM;
 456         }
 457         return 0;
 458 }
 459
 460 static struct pbe *swsusp_alloc(unsigned int nr_pages)
 461 {
 462         struct pbe *pblist;
 463
 464         if (!(pblist = alloc_pagedir(nr_pages, GFP_ATOMIC | __GFP_COLD, 0))) {
 465                 printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
 466                 return NULL;
 467         }
 468
 469         if (alloc_data_pages(pblist, GFP_ATOMIC | __GFP_COLD, 0)) {
 470                 printk(KERN_ERR "suspend: Allocating image pages failed.\n");
 471                 swsusp_free();
 472                 return NULL;
 473         }
 474
 475         return pblist;
 476 }
 477
 478 asmlinkage int swsusp_save(void)
 479 {
 480         unsigned int nr_pages;
 481
 482         pr_debug("swsusp: critical section: \n");
 483
 484         drain_local_pages();
 485         nr_pages = count_data_pages();
 486         printk("swsusp: Need to copy %u pages\n", nr_pages);
 487
 488         pr_debug("swsusp: pages needed: %u + %lu + %u, free: %u\n",
 489                  nr_pages,
 490                  (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE,
 491                  PAGES_FOR_IO, nr_free_pages());
 492
 493         if (!enough_free_mem(nr_pages)) {
 494                 printk(KERN_ERR "swsusp: Not enough free memory\n");
 495                 return -ENOMEM;
 496         }
 497
 498         pagedir_nosave = swsusp_alloc(nr_pages);
 499         if (!pagedir_nosave)
 500                 return -ENOMEM;
 501
 502         /* During allocating of suspend pagedir, new cold pages may appear.
 503          * Kill them.
 504          */
 505         drain_local_pages();
 506         copy_data_pages(pagedir_nosave);
 507
 508         /*
 509          * End of critical section. From now on, we can write to memory,
 510          * but we should not touch disk. This specially means we must _not_
 511          * touch swap space! Except we must write out our image of course.
 512          */
 513
 514         nr_copy_pages = nr_pages;
 515         nr_meta_pages = (nr_pages * sizeof(long) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 516
 517         printk("swsusp: critical section/: done (%d pages copied)\n", nr_pages);
 518         return 0;
 519 }
 520
 521 static void init_header(struct swsusp_info *info)
 522 {
 523         memset(info, 0, sizeof(struct swsusp_info));
 524         info->version_code = LINUX_VERSION_CODE;
 525         info->num_physpages = num_physpages;
 526         memcpy(&info->uts, &system_utsname, sizeof(system_utsname));
 527         info->cpus = num_online_cpus();
 528         info->image_pages = nr_copy_pages;
 529         info->pages = nr_copy_pages + nr_meta_pages + 1;
 530         info->size = info->pages;
 531         info->size <<= PAGE_SHIFT;
 532 }
 533
 534 /**
 535  *      pack_orig_addresses - the .orig_address fields of the PBEs from the
 536  *      list starting at @pbe are stored in the array @buf[] (1 page)
 537  */
 538
 539 static inline struct pbe *pack_orig_addresses(unsigned long *buf, struct pbe *pbe)
 540 {
 541         int j;
 542
 543         for (j = 0; j < PAGE_SIZE / sizeof(long) && pbe; j++) {
 544                 buf[j] = pbe->orig_address;
 545                 pbe = pbe->next;
 546         }
 547         if (!pbe)
 548                 for (; j < PAGE_SIZE / sizeof(long); j++)
 549                         buf[j] = 0;
 550         return pbe;
 551 }
 552
 553 /**
 554  *      snapshot_read_next - used for reading the system memory snapshot.
 555  *
 556  *      On the first call to it @handle should point to a zeroed
 557  *      snapshot_handle structure.  The structure gets updated and a pointer
 558  *      to it should be passed to this function every next time.
 559  *
 560  *      The @count parameter should contain the number of bytes the caller
 561  *      wants to read from the snapshot.  It must not be zero.
 562  *
 563  *      On success the function returns a positive number.  Then, the caller
 564  *      is allowed to read up to the returned number of bytes from the memory
 565  *      location computed by the data_of() macro.  The number returned
 566  *      may be smaller than @count, but this only happens if the read would
 567  *      cross a page boundary otherwise.
 568  *
 569  *      The function returns 0 to indicate the end of data stream condition,
 570  *      and a negative number is returned on error.  In such cases the
 571  *      structure pointed to by @handle is not updated and should not be used
 572  *      any more.
 573  */
 574
 575 int snapshot_read_next(struct snapshot_handle *handle, size_t count)
 576 {
 577         if (handle->page > nr_meta_pages + nr_copy_pages)
 578                 return 0;
 579         if (!buffer) {
 580                 /* This makes the buffer be freed by swsusp_free() */
 581                 buffer = alloc_image_page(GFP_ATOMIC, 0);
 582                 if (!buffer)
 583                         return -ENOMEM;
 584         }
 585         if (!handle->offset) {
 586                 init_header((struct swsusp_info *)buffer);
 587                 handle->buffer = buffer;
 588                 handle->pbe = pagedir_nosave;
 589         }
 590         if (handle->prev < handle->page) {
 591                 if (handle->page <= nr_meta_pages) {
 592                         handle->pbe = pack_orig_addresses(buffer, handle->pbe);
 593                         if (!handle->pbe)
 594                                 handle->pbe = pagedir_nosave;
 595                 } else {
 596                         handle->buffer = (void *)handle->pbe->address;
 597                         handle->pbe = handle->pbe->next;
 598                 }
 599                 handle->prev = handle->page;
 600         }
 601         handle->buf_offset = handle->page_offset;
 602         if (handle->page_offset + count >= PAGE_SIZE) {
 603                 count = PAGE_SIZE - handle->page_offset;
 604                 handle->page_offset = 0;
 605                 handle->page++;
 606         } else {
 607                 handle->page_offset += count;
 608         }
 609         handle->offset += count;
 610         return count;
 611 }
 612
 613 /**
 614  *      mark_unsafe_pages - mark the pages that cannot be used for storing
 615  *      the image during resume, because they conflict with the pages that
 616  *      had been used before suspend
 617  */
 618
 619 static int mark_unsafe_pages(struct pbe *pblist)
 620 {
 621         struct zone *zone;
 622         unsigned long zone_pfn;
 623         struct pbe *p;
 624
 625         if (!pblist) /* a sanity check */
 626                 return -EINVAL;
 627
 628         /* Clear page flags */
 629         for_each_zone (zone) {
 630                 for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
 631                         if (pfn_valid(zone_pfn + zone->zone_start_pfn))
 632                                 ClearPageNosaveFree(pfn_to_page(zone_pfn +
 633                                         zone->zone_start_pfn));
 634         }
 635
 636         /* Mark orig addresses */
 637         for_each_pbe (p, pblist) {
 638                 if (virt_addr_valid(p->orig_address))
 639                         SetPageNosaveFree(virt_to_page(p->orig_address));
 640                 else
 641                         return -EFAULT;
 642         }
 643
 644         return 0;
 645 }
 646
 647 static void copy_page_backup_list(struct pbe *dst, struct pbe *src)
 648 {
 649         /* We assume both lists contain the same number of elements */
 650         while (src) {
 651                 dst->orig_address = src->orig_address;
 652                 dst = dst->next;
 653                 src = src->next;
 654         }
 655 }
 656
 657 static int check_header(struct swsusp_info *info)
 658 {
 659         char *reason = NULL;
 660
 661         if (info->version_code != LINUX_VERSION_CODE)
 662                 reason = "kernel version";
 663         if (info->num_physpages != num_physpages)
 664                 reason = "memory size";
 665         if (strcmp(info->uts.sysname,system_utsname.sysname))
 666                 reason = "system type";
 667         if (strcmp(info->uts.release,system_utsname.release))
 668                 reason = "kernel release";
 669         if (strcmp(info->uts.version,system_utsname.version))
 670                 reason = "version";
 671         if (strcmp(info->uts.machine,system_utsname.machine))
 672                 reason = "machine";
 673         if (reason) {
 674                 printk(KERN_ERR "swsusp: Resume mismatch: %s\n", reason);
 675                 return -EPERM;
 676         }
 677         return 0;
 678 }
 679
 680 /**
 681  *      load header - check the image header and copy data from it
 682  */
 683
 684 static int load_header(struct snapshot_handle *handle,
 685                               struct swsusp_info *info)
 686 {
 687         int error;
 688         struct pbe *pblist;
 689
 690         error = check_header(info);
 691         if (!error) {
 692                 pblist = alloc_pagedir(info->image_pages, GFP_ATOMIC, 0);
 693                 if (!pblist)
 694                         return -ENOMEM;
 695                 pagedir_nosave = pblist;
 696                 handle->pbe = pblist;
 697                 nr_copy_pages = info->image_pages;
 698                 nr_meta_pages = info->pages - info->image_pages - 1;
 699         }
 700         return error;
 701 }
 702
 703 /**
 704  *      unpack_orig_addresses - copy the elements of @buf[] (1 page) to
 705  *      the PBEs in the list starting at @pbe
 706  */
 707
 708 static inline struct pbe *unpack_orig_addresses(unsigned long *buf,
 709                                                 struct pbe *pbe)
 710 {
 711         int j;
 712
 713         for (j = 0; j < PAGE_SIZE / sizeof(long) && pbe; j++) {
 714                 pbe->orig_address = buf[j];
 715                 pbe = pbe->next;
 716         }
 717         return pbe;
 718 }
 719
 720 /**
 721  *      create_image - use metadata contained in the PBE list
 722  *      pointed to by pagedir_nosave to mark the pages that will
 723  *      be overwritten in the process of restoring the system
 724  *      memory state from the image and allocate memory for
 725  *      the image avoiding these pages
 726  */
 727
 728 static int create_image(struct snapshot_handle *handle)
 729 {
 730         int error = 0;
 731         struct pbe *p, *pblist;
 732
 733         p = pagedir_nosave;
 734         error = mark_unsafe_pages(p);
 735         if (!error) {
 736                 pblist = alloc_pagedir(nr_copy_pages, GFP_ATOMIC, 1);
 737                 if (pblist)
 738                         copy_page_backup_list(pblist, p);
 739                 free_pagedir(p);
 740                 if (!pblist)
 741                         error = -ENOMEM;
 742         }
 743         if (!error)
 744                 error = alloc_data_pages(pblist, GFP_ATOMIC, 1);
 745         if (!error) {
 746                 release_eaten_pages();
 747                 pagedir_nosave = pblist;
 748         } else {
 749                 pagedir_nosave = NULL;
 750                 handle->pbe = NULL;
 751                 nr_copy_pages = 0;
 752                 nr_meta_pages = 0;
 753         }
 754         return error;
 755 }
 756
 757 /**
 758  *      snapshot_write_next - used for writing the system memory snapshot.
 759  *
 760  *      On the first call to it @handle should point to a zeroed
 761  *      snapshot_handle structure.  The structure gets updated and a pointer
 762  *      to it should be passed to this function every next time.
 763  *
 764  *      The @count parameter should contain the number of bytes the caller
 765  *      wants to write to the image.  It must not be zero.
 766  *
 767  *      On success the function returns a positive number.  Then, the caller
 768  *      is allowed to write up to the returned number of bytes to the memory
 769  *      location computed by the data_of() macro.  The number returned
 770  *      may be smaller than @count, but this only happens if the write would
 771  *      cross a page boundary otherwise.
 772  *
 773  *      The function returns 0 to indicate the "end of file" condition,
 774  *      and a negative number is returned on error.  In such cases the
 775  *      structure pointed to by @handle is not updated and should not be used
 776  *      any more.
 777  */
 778
 779 int snapshot_write_next(struct snapshot_handle *handle, size_t count)
 780 {
 781         int error = 0;
 782
 783         if (handle->prev && handle->page > nr_meta_pages + nr_copy_pages)
 784                 return 0;
 785         if (!buffer) {
 786                 /* This makes the buffer be freed by swsusp_free() */
 787                 buffer = alloc_image_page(GFP_ATOMIC, 0);
 788                 if (!buffer)
 789                         return -ENOMEM;
 790         }
 791         if (!handle->offset)
 792                 handle->buffer = buffer;
 793         if (handle->prev < handle->page) {
 794                 if (!handle->prev) {
 795                         error = load_header(handle, (struct swsusp_info *)buffer);
 796                         if (error)
 797                                 return error;
 798                 } else if (handle->prev <= nr_meta_pages) {
 799                         handle->pbe = unpack_orig_addresses(buffer, handle->pbe);
 800                         if (!handle->pbe) {
 801                                 error = create_image(handle);
 802                                 if (error)
 803                                         return error;
 804                                 handle->pbe = pagedir_nosave;
 805                                 handle->buffer = (void *)handle->pbe->address;
 806                         }
 807                 } else {
 808                         handle->pbe = handle->pbe->next;
 809                         handle->buffer = (void *)handle->pbe->address;
 810                 }
 811                 handle->prev = handle->page;
 812         }
 813         handle->buf_offset = handle->page_offset;
 814         if (handle->page_offset + count >= PAGE_SIZE) {
 815                 count = PAGE_SIZE - handle->page_offset;
 816                 handle->page_offset = 0;
 817                 handle->page++;
 818         } else {
 819                 handle->page_offset += count;
 820         }
 821         handle->offset += count;
 822         return count;
 823 }
 824
 825 int snapshot_image_loaded(struct snapshot_handle *handle)
 826 {
 827         return !(!handle->pbe || handle->pbe->next || !nr_copy_pages ||
 828                 handle->page <= nr_meta_pages + nr_copy_pages);
 829 }