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 #else
 154 static inline unsigned int count_highmem_pages(void) {return 0;}
 155 static inline int save_highmem(void) {return 0;}
 156 static inline int restore_highmem(void) {return 0;}
 157 #endif
 158
 159 static inline int pfn_is_nosave(unsigned long pfn)
 160 {
 161         unsigned long nosave_begin_pfn = __pa(&__nosave_begin) >> PAGE_SHIFT;
 162         unsigned long nosave_end_pfn = PAGE_ALIGN(__pa(&__nosave_end)) >> PAGE_SHIFT;
 163         return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
 164 }
 165
 166 /**
 167  *      saveable - Determine whether a page should be cloned or not.
 168  *      @pfn:   The page
 169  *
 170  *      We save a page if it isn't Nosave, and is not in the range of pages
 171  *      statically defined as 'unsaveable', and it
 172  *      isn't a part of a free chunk of pages.
 173  */
 174
 175 static struct page *saveable_page(unsigned long pfn)
 176 {
 177         struct page *page;
 178
 179         if (!pfn_valid(pfn))
 180                 return NULL;
 181
 182         page = pfn_to_page(pfn);
 183
 184         if (PageNosave(page))
 185                 return NULL;
 186         if (PageReserved(page) && pfn_is_nosave(pfn))
 187                 return NULL;
 188         if (PageNosaveFree(page))
 189                 return NULL;
 190
 191         return page;
 192 }
 193
 194 unsigned int count_data_pages(void)
 195 {
 196         struct zone *zone;
 197         unsigned long pfn, max_zone_pfn;
 198         unsigned int n = 0;
 199
 200         for_each_zone (zone) {
 201                 if (is_highmem(zone))
 202                         continue;
 203                 mark_free_pages(zone);
 204                 max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
 205                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
 206                         n += !!saveable_page(pfn);
 207         }
 208         return n;
 209 }
 210
 211 static void copy_data_pages(struct pbe *pblist)
 212 {
 213         struct zone *zone;
 214         unsigned long pfn, max_zone_pfn;
 215         struct pbe *pbe, *p;
 216
 217         pbe = pblist;
 218         for_each_zone (zone) {
 219                 if (is_highmem(zone))
 220                         continue;
 221                 mark_free_pages(zone);
 222                 /* This is necessary for swsusp_free() */
 223                 for_each_pb_page (p, pblist)
 224                         SetPageNosaveFree(virt_to_page(p));
 225                 for_each_pbe (p, pblist)
 226                         SetPageNosaveFree(virt_to_page(p->address));
 227                 max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
 228                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
 229                         struct page *page = saveable_page(pfn);
 230
 231                         if (page) {
 232                                 long *src, *dst;
 233                                 int n;
 234
 235                                 BUG_ON(!pbe);
 236                                 pbe->orig_address = (unsigned long)page_address(page);
 237                                 /* copy_page and memcpy are not usable for copying task structs. */
 238                                 dst = (long *)pbe->address;
 239                                 src = (long *)pbe->orig_address;
 240                                 for (n = PAGE_SIZE / sizeof(long); n; n--)
 241                                         *dst++ = *src++;
 242                                 pbe = pbe->next;
 243                         }
 244                 }
 245         }
 246         BUG_ON(pbe);
 247 }
 248
 249
 250 /**
 251  *      free_pagedir - free pages allocated with alloc_pagedir()
 252  */
 253
 254 static void free_pagedir(struct pbe *pblist, int clear_nosave_free)
 255 {
 256         struct pbe *pbe;
 257
 258         while (pblist) {
 259                 pbe = (pblist + PB_PAGE_SKIP)->next;
 260                 ClearPageNosave(virt_to_page(pblist));
 261                 if (clear_nosave_free)
 262                         ClearPageNosaveFree(virt_to_page(pblist));
 263                 free_page((unsigned long)pblist);
 264                 pblist = pbe;
 265         }
 266 }
 267
 268 /**
 269  *      fill_pb_page - Create a list of PBEs on a given memory page
 270  */
 271
 272 static inline void fill_pb_page(struct pbe *pbpage)
 273 {
 274         struct pbe *p;
 275
 276         p = pbpage;
 277         pbpage += PB_PAGE_SKIP;
 278         do
 279                 p->next = p + 1;
 280         while (++p < pbpage);
 281 }
 282
 283 /**
 284  *      create_pbe_list - Create a list of PBEs on top of a given chain
 285  *      of memory pages allocated with alloc_pagedir()
 286  */
 287
 288 static inline void create_pbe_list(struct pbe *pblist, unsigned int nr_pages)
 289 {
 290         struct pbe *pbpage, *p;
 291         unsigned int num = PBES_PER_PAGE;
 292
 293         for_each_pb_page (pbpage, pblist) {
 294                 if (num >= nr_pages)
 295                         break;
 296
 297                 fill_pb_page(pbpage);
 298                 num += PBES_PER_PAGE;
 299         }
 300         if (pbpage) {
 301                 for (num -= PBES_PER_PAGE - 1, p = pbpage; num < nr_pages; p++, num++)
 302                         p->next = p + 1;
 303                 p->next = NULL;
 304         }
 305 }
 306
 307 static unsigned int unsafe_pages;
 308
 309 /**
 310  *      @safe_needed - on resume, for storing the PBE list and the image,
 311  *      we can only use memory pages that do not conflict with the pages
 312  *      used before suspend.
 313  *
 314  *      The unsafe pages are marked with the PG_nosave_free flag
 315  *      and we count them using unsafe_pages
 316  */
 317
 318 static void *alloc_image_page(gfp_t gfp_mask, int safe_needed)
 319 {
 320         void *res;
 321
 322         res = (void *)get_zeroed_page(gfp_mask);
 323         if (safe_needed)
 324                 while (res && PageNosaveFree(virt_to_page(res))) {
 325                         /* The page is unsafe, mark it for swsusp_free() */
 326                         SetPageNosave(virt_to_page(res));
 327                         unsafe_pages++;
 328                         res = (void *)get_zeroed_page(gfp_mask);
 329                 }
 330         if (res) {
 331                 SetPageNosave(virt_to_page(res));
 332                 SetPageNosaveFree(virt_to_page(res));
 333         }
 334         return res;
 335 }
 336
 337 unsigned long get_safe_page(gfp_t gfp_mask)
 338 {
 339         return (unsigned long)alloc_image_page(gfp_mask, 1);
 340 }
 341
 342 /**
 343  *      alloc_pagedir - Allocate the page directory.
 344  *
 345  *      First, determine exactly how many pages we need and
 346  *      allocate them.
 347  *
 348  *      We arrange the pages in a chain: each page is an array of PBES_PER_PAGE
 349  *      struct pbe elements (pbes) and the last element in the page points
 350  *      to the next page.
 351  *
 352  *      On each page we set up a list of struct_pbe elements.
 353  */
 354
 355 static struct pbe *alloc_pagedir(unsigned int nr_pages, gfp_t gfp_mask,
 356                                  int safe_needed)
 357 {
 358         unsigned int num;
 359         struct pbe *pblist, *pbe;
 360
 361         if (!nr_pages)
 362                 return NULL;
 363
 364         pblist = alloc_image_page(gfp_mask, safe_needed);
 365         /* FIXME: rewrite this ugly loop */
 366         for (pbe = pblist, num = PBES_PER_PAGE; pbe && num < nr_pages;
 367                         pbe = pbe->next, num += PBES_PER_PAGE) {
 368                 pbe += PB_PAGE_SKIP;
 369                 pbe->next = alloc_image_page(gfp_mask, safe_needed);
 370         }
 371         if (!pbe) { /* get_zeroed_page() failed */
 372                 free_pagedir(pblist, 1);
 373                 pblist = NULL;
 374         } else
 375                 create_pbe_list(pblist, nr_pages);
 376         return pblist;
 377 }
 378
 379 /**
 380  * Free pages we allocated for suspend. Suspend pages are alocated
 381  * before atomic copy, so we need to free them after resume.
 382  */
 383
 384 void swsusp_free(void)
 385 {
 386         struct zone *zone;
 387         unsigned long pfn, max_zone_pfn;
 388
 389         for_each_zone(zone) {
 390                 max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
 391                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
 392                         if (pfn_valid(pfn)) {
 393                                 struct page *page = pfn_to_page(pfn);
 394
 395                                 if (PageNosave(page) && PageNosaveFree(page)) {
 396                                         ClearPageNosave(page);
 397                                         ClearPageNosaveFree(page);
 398                                         free_page((long) page_address(page));
 399                                 }
 400                         }
 401         }
 402         nr_copy_pages = 0;
 403         nr_meta_pages = 0;
 404         pagedir_nosave = NULL;
 405         buffer = NULL;
 406 }
 407
 408
 409 /**
 410  *      enough_free_mem - Make sure we enough free memory to snapshot.
 411  *
 412  *      Returns TRUE or FALSE after checking the number of available
 413  *      free pages.
 414  */
 415
 416 static int enough_free_mem(unsigned int nr_pages)
 417 {
 418         struct zone *zone;
 419         unsigned int n = 0;
 420
 421         for_each_zone (zone)
 422                 if (!is_highmem(zone))
 423                         n += zone->free_pages;
 424         pr_debug("swsusp: available memory: %u pages\n", n);
 425         return n > (nr_pages + PAGES_FOR_IO +
 426                 (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
 427 }
 428
 429 static int alloc_data_pages(struct pbe *pblist, gfp_t gfp_mask, int safe_needed)
 430 {
 431         struct pbe *p;
 432
 433         for_each_pbe (p, pblist) {
 434                 p->address = (unsigned long)alloc_image_page(gfp_mask, safe_needed);
 435                 if (!p->address)
 436                         return -ENOMEM;
 437         }
 438         return 0;
 439 }
 440
 441 static struct pbe *swsusp_alloc(unsigned int nr_pages)
 442 {
 443         struct pbe *pblist;
 444
 445         if (!(pblist = alloc_pagedir(nr_pages, GFP_ATOMIC | __GFP_COLD, 0))) {
 446                 printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
 447                 return NULL;
 448         }
 449
 450         if (alloc_data_pages(pblist, GFP_ATOMIC | __GFP_COLD, 0)) {
 451                 printk(KERN_ERR "suspend: Allocating image pages failed.\n");
 452                 swsusp_free();
 453                 return NULL;
 454         }
 455
 456         return pblist;
 457 }
 458
 459 asmlinkage int swsusp_save(void)
 460 {
 461         unsigned int nr_pages;
 462
 463         pr_debug("swsusp: critical section: \n");
 464
 465         drain_local_pages();
 466         nr_pages = count_data_pages();
 467         printk("swsusp: Need to copy %u pages\n", nr_pages);
 468
 469         pr_debug("swsusp: pages needed: %u + %lu + %u, free: %u\n",
 470                  nr_pages,
 471                  (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE,
 472                  PAGES_FOR_IO, nr_free_pages());
 473
 474         if (!enough_free_mem(nr_pages)) {
 475                 printk(KERN_ERR "swsusp: Not enough free memory\n");
 476                 return -ENOMEM;
 477         }
 478
 479         pagedir_nosave = swsusp_alloc(nr_pages);
 480         if (!pagedir_nosave)
 481                 return -ENOMEM;
 482
 483         /* During allocating of suspend pagedir, new cold pages may appear.
 484          * Kill them.
 485          */
 486         drain_local_pages();
 487         copy_data_pages(pagedir_nosave);
 488
 489         /*
 490          * End of critical section. From now on, we can write to memory,
 491          * but we should not touch disk. This specially means we must _not_
 492          * touch swap space! Except we must write out our image of course.
 493          */
 494
 495         nr_copy_pages = nr_pages;
 496         nr_meta_pages = (nr_pages * sizeof(long) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 497
 498         printk("swsusp: critical section/: done (%d pages copied)\n", nr_pages);
 499         return 0;
 500 }
 501
 502 static void init_header(struct swsusp_info *info)
 503 {
 504         memset(info, 0, sizeof(struct swsusp_info));
 505         info->version_code = LINUX_VERSION_CODE;
 506         info->num_physpages = num_physpages;
 507         memcpy(&info->uts, &system_utsname, sizeof(system_utsname));
 508         info->cpus = num_online_cpus();
 509         info->image_pages = nr_copy_pages;
 510         info->pages = nr_copy_pages + nr_meta_pages + 1;
 511         info->size = info->pages;
 512         info->size <<= PAGE_SHIFT;
 513 }
 514
 515 /**
 516  *      pack_orig_addresses - the .orig_address fields of the PBEs from the
 517  *      list starting at @pbe are stored in the array @buf[] (1 page)
 518  */
 519
 520 static inline struct pbe *pack_orig_addresses(unsigned long *buf, struct pbe *pbe)
 521 {
 522         int j;
 523
 524         for (j = 0; j < PAGE_SIZE / sizeof(long) && pbe; j++) {
 525                 buf[j] = pbe->orig_address;
 526                 pbe = pbe->next;
 527         }
 528         if (!pbe)
 529                 for (; j < PAGE_SIZE / sizeof(long); j++)
 530                         buf[j] = 0;
 531         return pbe;
 532 }
 533
 534 /**
 535  *      snapshot_read_next - used for reading the system memory snapshot.
 536  *
 537  *      On the first call to it @handle should point to a zeroed
 538  *      snapshot_handle structure.  The structure gets updated and a pointer
 539  *      to it should be passed to this function every next time.
 540  *
 541  *      The @count parameter should contain the number of bytes the caller
 542  *      wants to read from the snapshot.  It must not be zero.
 543  *
 544  *      On success the function returns a positive number.  Then, the caller
 545  *      is allowed to read up to the returned number of bytes from the memory
 546  *      location computed by the data_of() macro.  The number returned
 547  *      may be smaller than @count, but this only happens if the read would
 548  *      cross a page boundary otherwise.
 549  *
 550  *      The function returns 0 to indicate the end of data stream condition,
 551  *      and a negative number is returned on error.  In such cases the
 552  *      structure pointed to by @handle is not updated and should not be used
 553  *      any more.
 554  */
 555
 556 int snapshot_read_next(struct snapshot_handle *handle, size_t count)
 557 {
 558         if (handle->cur > nr_meta_pages + nr_copy_pages)
 559                 return 0;
 560         if (!buffer) {
 561                 /* This makes the buffer be freed by swsusp_free() */
 562                 buffer = alloc_image_page(GFP_ATOMIC, 0);
 563                 if (!buffer)
 564                         return -ENOMEM;
 565         }
 566         if (!handle->offset) {
 567                 init_header((struct swsusp_info *)buffer);
 568                 handle->buffer = buffer;
 569                 handle->pbe = pagedir_nosave;
 570         }
 571         if (handle->prev < handle->cur) {
 572                 if (handle->cur <= nr_meta_pages) {
 573                         handle->pbe = pack_orig_addresses(buffer, handle->pbe);
 574                         if (!handle->pbe)
 575                                 handle->pbe = pagedir_nosave;
 576                 } else {
 577                         handle->buffer = (void *)handle->pbe->address;
 578                         handle->pbe = handle->pbe->next;
 579                 }
 580                 handle->prev = handle->cur;
 581         }
 582         handle->buf_offset = handle->cur_offset;
 583         if (handle->cur_offset + count >= PAGE_SIZE) {
 584                 count = PAGE_SIZE - handle->cur_offset;
 585                 handle->cur_offset = 0;
 586                 handle->cur++;
 587         } else {
 588                 handle->cur_offset += count;
 589         }
 590         handle->offset += count;
 591         return count;
 592 }
 593
 594 /**
 595  *      mark_unsafe_pages - mark the pages that cannot be used for storing
 596  *      the image during resume, because they conflict with the pages that
 597  *      had been used before suspend
 598  */
 599
 600 static int mark_unsafe_pages(struct pbe *pblist)
 601 {
 602         struct zone *zone;
 603         unsigned long pfn, max_zone_pfn;
 604         struct pbe *p;
 605
 606         if (!pblist) /* a sanity check */
 607                 return -EINVAL;
 608
 609         /* Clear page flags */
 610         for_each_zone (zone) {
 611                 max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
 612                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
 613                         if (pfn_valid(pfn))
 614                                 ClearPageNosaveFree(pfn_to_page(pfn));
 615         }
 616
 617         /* Mark orig addresses */
 618         for_each_pbe (p, pblist) {
 619                 if (virt_addr_valid(p->orig_address))
 620                         SetPageNosaveFree(virt_to_page(p->orig_address));
 621                 else
 622                         return -EFAULT;
 623         }
 624
 625         unsafe_pages = 0;
 626
 627         return 0;
 628 }
 629
 630 static void copy_page_backup_list(struct pbe *dst, struct pbe *src)
 631 {
 632         /* We assume both lists contain the same number of elements */
 633         while (src) {
 634                 dst->orig_address = src->orig_address;
 635                 dst = dst->next;
 636                 src = src->next;
 637         }
 638 }
 639
 640 static int check_header(struct swsusp_info *info)
 641 {
 642         char *reason = NULL;
 643
 644         if (info->version_code != LINUX_VERSION_CODE)
 645                 reason = "kernel version";
 646         if (info->num_physpages != num_physpages)
 647                 reason = "memory size";
 648         if (strcmp(info->uts.sysname,system_utsname.sysname))
 649                 reason = "system type";
 650         if (strcmp(info->uts.release,system_utsname.release))
 651                 reason = "kernel release";
 652         if (strcmp(info->uts.version,system_utsname.version))
 653                 reason = "version";
 654         if (strcmp(info->uts.machine,system_utsname.machine))
 655                 reason = "machine";
 656         if (reason) {
 657                 printk(KERN_ERR "swsusp: Resume mismatch: %s\n", reason);
 658                 return -EPERM;
 659         }
 660         return 0;
 661 }
 662
 663 /**
 664  *      load header - check the image header and copy data from it
 665  */
 666
 667 static int load_header(struct snapshot_handle *handle,
 668                               struct swsusp_info *info)
 669 {
 670         int error;
 671         struct pbe *pblist;
 672
 673         error = check_header(info);
 674         if (!error) {
 675                 pblist = alloc_pagedir(info->image_pages, GFP_ATOMIC, 0);
 676                 if (!pblist)
 677                         return -ENOMEM;
 678                 pagedir_nosave = pblist;
 679                 handle->pbe = pblist;
 680                 nr_copy_pages = info->image_pages;
 681                 nr_meta_pages = info->pages - info->image_pages - 1;
 682         }
 683         return error;
 684 }
 685
 686 /**
 687  *      unpack_orig_addresses - copy the elements of @buf[] (1 page) to
 688  *      the PBEs in the list starting at @pbe
 689  */
 690
 691 static inline struct pbe *unpack_orig_addresses(unsigned long *buf,
 692                                                 struct pbe *pbe)
 693 {
 694         int j;
 695
 696         for (j = 0; j < PAGE_SIZE / sizeof(long) && pbe; j++) {
 697                 pbe->orig_address = buf[j];
 698                 pbe = pbe->next;
 699         }
 700         return pbe;
 701 }
 702
 703 /**
 704  *      prepare_image - use metadata contained in the PBE list
 705  *      pointed to by pagedir_nosave to mark the pages that will
 706  *      be overwritten in the process of restoring the system
 707  *      memory state from the image ("unsafe" pages) and allocate
 708  *      memory for the image
 709  *
 710  *      The idea is to allocate the PBE list first and then
 711  *      allocate as many pages as it's needed for the image data,
 712  *      but not to assign these pages to the PBEs initially.
 713  *      Instead, we just mark them as allocated and create a list
 714  *      of "safe" which will be used later
 715  */
 716
 717 struct safe_page {
 718         struct safe_page *next;
 719         char padding[PAGE_SIZE - sizeof(void *)];
 720 };
 721
 722 static struct safe_page *safe_pages;
 723
 724 static int prepare_image(struct snapshot_handle *handle)
 725 {
 726         int error = 0;
 727         unsigned int nr_pages = nr_copy_pages;
 728         struct pbe *p, *pblist = NULL;
 729
 730         p = pagedir_nosave;
 731         error = mark_unsafe_pages(p);
 732         if (!error) {
 733                 pblist = alloc_pagedir(nr_pages, GFP_ATOMIC, 1);
 734                 if (pblist)
 735                         copy_page_backup_list(pblist, p);
 736                 free_pagedir(p, 0);
 737                 if (!pblist)
 738                         error = -ENOMEM;
 739         }
 740         safe_pages = NULL;
 741         if (!error && nr_pages > unsafe_pages) {
 742                 nr_pages -= unsafe_pages;
 743                 while (nr_pages--) {
 744                         struct safe_page *ptr;
 745
 746                         ptr = (struct safe_page *)get_zeroed_page(GFP_ATOMIC);
 747                         if (!ptr) {
 748                                 error = -ENOMEM;
 749                                 break;
 750                         }
 751                         if (!PageNosaveFree(virt_to_page(ptr))) {
 752                                 /* The page is "safe", add it to the list */
 753                                 ptr->next = safe_pages;
 754                                 safe_pages = ptr;
 755                         }
 756                         /* Mark the page as allocated */
 757                         SetPageNosave(virt_to_page(ptr));
 758                         SetPageNosaveFree(virt_to_page(ptr));
 759                 }
 760         }
 761         if (!error) {
 762                 pagedir_nosave = pblist;
 763         } else {
 764                 handle->pbe = NULL;
 765                 swsusp_free();
 766         }
 767         return error;
 768 }
 769
 770 static void *get_buffer(struct snapshot_handle *handle)
 771 {
 772         struct pbe *pbe = handle->pbe, *last = handle->last_pbe;
 773         struct page *page = virt_to_page(pbe->orig_address);
 774
 775         if (PageNosave(page) && PageNosaveFree(page)) {
 776                 /*
 777                  * We have allocated the "original" page frame and we can
 778                  * use it directly to store the read page
 779                  */
 780                 pbe->address = 0;
 781                 if (last && last->next)
 782                         last->next = NULL;
 783                 return (void *)pbe->orig_address;
 784         }
 785         /*
 786          * The "original" page frame has not been allocated and we have to
 787          * use a "safe" page frame to store the read page
 788          */
 789         pbe->address = (unsigned long)safe_pages;
 790         safe_pages = safe_pages->next;
 791         if (last)
 792                 last->next = pbe;
 793         handle->last_pbe = pbe;
 794         return (void *)pbe->address;
 795 }
 796
 797 /**
 798  *      snapshot_write_next - used for writing the system memory snapshot.
 799  *
 800  *      On the first call to it @handle should point to a zeroed
 801  *      snapshot_handle structure.  The structure gets updated and a pointer
 802  *      to it should be passed to this function every next time.
 803  *
 804  *      The @count parameter should contain the number of bytes the caller
 805  *      wants to write to the image.  It must not be zero.
 806  *
 807  *      On success the function returns a positive number.  Then, the caller
 808  *      is allowed to write up to the returned number of bytes to the memory
 809  *      location computed by the data_of() macro.  The number returned
 810  *      may be smaller than @count, but this only happens if the write would
 811  *      cross a page boundary otherwise.
 812  *
 813  *      The function returns 0 to indicate the "end of file" condition,
 814  *      and a negative number is returned on error.  In such cases the
 815  *      structure pointed to by @handle is not updated and should not be used
 816  *      any more.
 817  */
 818
 819 int snapshot_write_next(struct snapshot_handle *handle, size_t count)
 820 {
 821         int error = 0;
 822
 823         if (handle->prev && handle->cur > nr_meta_pages + nr_copy_pages)
 824                 return 0;
 825         if (!buffer) {
 826                 /* This makes the buffer be freed by swsusp_free() */
 827                 buffer = alloc_image_page(GFP_ATOMIC, 0);
 828                 if (!buffer)
 829                         return -ENOMEM;
 830         }
 831         if (!handle->offset)
 832                 handle->buffer = buffer;
 833         handle->sync_read = 1;
 834         if (handle->prev < handle->cur) {
 835                 if (!handle->prev) {
 836                         error = load_header(handle,
 837                                         (struct swsusp_info *)buffer);
 838                         if (error)
 839                                 return error;
 840                 } else if (handle->prev <= nr_meta_pages) {
 841                         handle->pbe = unpack_orig_addresses(buffer,
 842                                                         handle->pbe);
 843                         if (!handle->pbe) {
 844                                 error = prepare_image(handle);
 845                                 if (error)
 846                                         return error;
 847                                 handle->pbe = pagedir_nosave;
 848                                 handle->last_pbe = NULL;
 849                                 handle->buffer = get_buffer(handle);
 850                                 handle->sync_read = 0;
 851                         }
 852                 } else {
 853                         handle->pbe = handle->pbe->next;
 854                         handle->buffer = get_buffer(handle);
 855                         handle->sync_read = 0;
 856                 }
 857                 handle->prev = handle->cur;
 858         }
 859         handle->buf_offset = handle->cur_offset;
 860         if (handle->cur_offset + count >= PAGE_SIZE) {
 861                 count = PAGE_SIZE - handle->cur_offset;
 862                 handle->cur_offset = 0;
 863                 handle->cur++;
 864         } else {
 865                 handle->cur_offset += count;
 866         }
 867         handle->offset += count;
 868         return count;
 869 }
 870
 871 int snapshot_image_loaded(struct snapshot_handle *handle)
 872 {
 873         return !(!handle->pbe || handle->pbe->next || !nr_copy_pages ||
 874                 handle->cur <= nr_meta_pages + nr_copy_pages);
 875 }