err.no Git - linux-2.6/blob - 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 struct arch_saveable_page {
  43         unsigned long start;
  44         unsigned long end;
  45         char *data;
  46         struct arch_saveable_page *next;
  47 };
  48 static struct arch_saveable_page *arch_pages;
  49
  50 int swsusp_add_arch_pages(unsigned long start, unsigned long end)
  51 {
  52         struct arch_saveable_page *tmp;
  53
  54         while (start < end) {
  55                 tmp = kzalloc(sizeof(struct arch_saveable_page), GFP_KERNEL);
  56                 if (!tmp)
  57                         return -ENOMEM;
  58                 tmp->start = start;
  59                 tmp->end = ((start >> PAGE_SHIFT) + 1) << PAGE_SHIFT;
  60                 if (tmp->end > end)
  61                         tmp->end = end;
  62                 tmp->next = arch_pages;
  63                 start = tmp->end;
  64                 arch_pages = tmp;
  65         }
  66         return 0;
  67 }
  68
  69 static unsigned int count_arch_pages(void)
  70 {
  71         unsigned int count = 0;
  72         struct arch_saveable_page *tmp = arch_pages;
  73         while (tmp) {
  74                 count++;
  75                 tmp = tmp->next;
  76         }
  77         return count;
  78 }
  79
  80 static int save_arch_mem(void)
  81 {
  82         char *kaddr;
  83         struct arch_saveable_page *tmp = arch_pages;
  84         int offset;
  85
  86         pr_debug("swsusp: Saving arch specific memory");
  87         while (tmp) {
  88                 tmp->data = (char *)__get_free_page(GFP_ATOMIC);
  89                 if (!tmp->data)
  90                         return -ENOMEM;
  91                 offset = tmp->start - (tmp->start & PAGE_MASK);
  92                 /* arch pages might haven't a 'struct page' */
  93                 kaddr = kmap_atomic_pfn(tmp->start >> PAGE_SHIFT, KM_USER0);
  94                 memcpy(tmp->data + offset, kaddr + offset,
  95                         tmp->end - tmp->start);
  96                 kunmap_atomic(kaddr, KM_USER0);
  97
  98                 tmp = tmp->next;
  99         }
 100         return 0;
 101 }
 102
 103 static int restore_arch_mem(void)
 104 {
 105         char *kaddr;
 106         struct arch_saveable_page *tmp = arch_pages;
 107         int offset;
 108
 109         while (tmp) {
 110                 if (!tmp->data)
 111                         continue;
 112                 offset = tmp->start - (tmp->start & PAGE_MASK);
 113                 kaddr = kmap_atomic_pfn(tmp->start >> PAGE_SHIFT, KM_USER0);
 114                 memcpy(kaddr + offset, tmp->data + offset,
 115                         tmp->end - tmp->start);
 116                 kunmap_atomic(kaddr, KM_USER0);
 117                 free_page((long)tmp->data);
 118                 tmp->data = NULL;
 119                 tmp = tmp->next;
 120         }
 121         return 0;
 122 }
 123
 124 #ifdef CONFIG_HIGHMEM
 125 static unsigned int count_highmem_pages(void)
 126 {
 127         struct zone *zone;
 128         unsigned long zone_pfn;
 129         unsigned int n = 0;
 130
 131         for_each_zone (zone)
 132                 if (is_highmem(zone)) {
 133                         mark_free_pages(zone);
 134                         for (zone_pfn = 0; zone_pfn < zone->spanned_pages; zone_pfn++) {
 135                                 struct page *page;
 136                                 unsigned long pfn = zone_pfn + zone->zone_start_pfn;
 137                                 if (!pfn_valid(pfn))
 138                                         continue;
 139                                 page = pfn_to_page(pfn);
 140                                 if (PageReserved(page))
 141                                         continue;
 142                                 if (PageNosaveFree(page))
 143                                         continue;
 144                                 n++;
 145                         }
 146                 }
 147         return n;
 148 }
 149
 150 struct highmem_page {
 151         char *data;
 152         struct page *page;
 153         struct highmem_page *next;
 154 };
 155
 156 static struct highmem_page *highmem_copy;
 157
 158 static int save_highmem_zone(struct zone *zone)
 159 {
 160         unsigned long zone_pfn;
 161         mark_free_pages(zone);
 162         for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
 163                 struct page *page;
 164                 struct highmem_page *save;
 165                 void *kaddr;
 166                 unsigned long pfn = zone_pfn + zone->zone_start_pfn;
 167
 168                 if (!(pfn%10000))
 169                         printk(".");
 170                 if (!pfn_valid(pfn))
 171                         continue;
 172                 page = pfn_to_page(pfn);
 173                 /*
 174                  * This condition results from rvmalloc() sans vmalloc_32()
 175                  * and architectural memory reservations. This should be
 176                  * corrected eventually when the cases giving rise to this
 177                  * are better understood.
 178                  */
 179                 if (PageReserved(page))
 180                         continue;
 181                 BUG_ON(PageNosave(page));
 182                 if (PageNosaveFree(page))
 183                         continue;
 184                 save = kmalloc(sizeof(struct highmem_page), GFP_ATOMIC);
 185                 if (!save)
 186                         return -ENOMEM;
 187                 save->next = highmem_copy;
 188                 save->page = page;
 189                 save->data = (void *) get_zeroed_page(GFP_ATOMIC);
 190                 if (!save->data) {
 191                         kfree(save);
 192                         return -ENOMEM;
 193                 }
 194                 kaddr = kmap_atomic(page, KM_USER0);
 195                 memcpy(save->data, kaddr, PAGE_SIZE);
 196                 kunmap_atomic(kaddr, KM_USER0);
 197                 highmem_copy = save;
 198         }
 199         return 0;
 200 }
 201
 202 static int save_highmem(void)
 203 {
 204         struct zone *zone;
 205         int res = 0;
 206
 207         pr_debug("swsusp: Saving Highmem");
 208         drain_local_pages();
 209         for_each_zone (zone) {
 210                 if (is_highmem(zone))
 211                         res = save_highmem_zone(zone);
 212                 if (res)
 213                         return res;
 214         }
 215         printk("\n");
 216         return 0;
 217 }
 218
 219 static int restore_highmem(void)
 220 {
 221         printk("swsusp: Restoring Highmem\n");
 222         while (highmem_copy) {
 223                 struct highmem_page *save = highmem_copy;
 224                 void *kaddr;
 225                 highmem_copy = save->next;
 226
 227                 kaddr = kmap_atomic(save->page, KM_USER0);
 228                 memcpy(kaddr, save->data, PAGE_SIZE);
 229                 kunmap_atomic(kaddr, KM_USER0);
 230                 free_page((long) save->data);
 231                 kfree(save);
 232         }
 233         return 0;
 234 }
 235 #else
 236 static inline unsigned int count_highmem_pages(void) {return 0;}
 237 static inline int save_highmem(void) {return 0;}
 238 static inline int restore_highmem(void) {return 0;}
 239 #endif
 240
 241 unsigned int count_special_pages(void)
 242 {
 243         return count_arch_pages() + count_highmem_pages();
 244 }
 245
 246 int save_special_mem(void)
 247 {
 248         int ret;
 249         ret = save_arch_mem();
 250         if (!ret)
 251                 ret = save_highmem();
 252         return ret;
 253 }
 254
 255 int restore_special_mem(void)
 256 {
 257         int ret;
 258         ret = restore_arch_mem();
 259         if (!ret)
 260                 ret = restore_highmem();
 261         return ret;
 262 }
 263
 264 static int pfn_is_nosave(unsigned long pfn)
 265 {
 266         unsigned long nosave_begin_pfn = __pa(&__nosave_begin) >> PAGE_SHIFT;
 267         unsigned long nosave_end_pfn = PAGE_ALIGN(__pa(&__nosave_end)) >> PAGE_SHIFT;
 268         return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
 269 }
 270
 271 /**
 272  *      saveable - Determine whether a page should be cloned or not.
 273  *      @pfn:   The page
 274  *
 275  *      We save a page if it's Reserved, and not in the range of pages
 276  *      statically defined as 'unsaveable', or if it isn't reserved, and
 277  *      isn't part of a free chunk of pages.
 278  */
 279
 280 static int saveable(struct zone *zone, unsigned long *zone_pfn)
 281 {
 282         unsigned long pfn = *zone_pfn + zone->zone_start_pfn;
 283         struct page *page;
 284
 285         if (!pfn_valid(pfn))
 286                 return 0;
 287
 288         page = pfn_to_page(pfn);
 289         if (PageNosave(page))
 290                 return 0;
 291         if (PageReserved(page) && pfn_is_nosave(pfn))
 292                 return 0;
 293         if (PageNosaveFree(page))
 294                 return 0;
 295
 296         return 1;
 297 }
 298
 299 unsigned int count_data_pages(void)
 300 {
 301         struct zone *zone;
 302         unsigned long zone_pfn;
 303         unsigned int n = 0;
 304
 305         for_each_zone (zone) {
 306                 if (is_highmem(zone))
 307                         continue;
 308                 mark_free_pages(zone);
 309                 for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
 310                         n += saveable(zone, &zone_pfn);
 311         }
 312         return n;
 313 }
 314
 315 static void copy_data_pages(struct pbe *pblist)
 316 {
 317         struct zone *zone;
 318         unsigned long zone_pfn;
 319         struct pbe *pbe, *p;
 320
 321         pbe = pblist;
 322         for_each_zone (zone) {
 323                 if (is_highmem(zone))
 324                         continue;
 325                 mark_free_pages(zone);
 326                 /* This is necessary for swsusp_free() */
 327                 for_each_pb_page (p, pblist)
 328                         SetPageNosaveFree(virt_to_page(p));
 329                 for_each_pbe (p, pblist)
 330                         SetPageNosaveFree(virt_to_page(p->address));
 331                 for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
 332                         if (saveable(zone, &zone_pfn)) {
 333                                 struct page *page;
 334                                 page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
 335                                 BUG_ON(!pbe);
 336                                 pbe->orig_address = (unsigned long)page_address(page);
 337                                 /* copy_page is not usable for copying task structs. */
 338                                 memcpy((void *)pbe->address, (void *)pbe->orig_address, PAGE_SIZE);
 339                                 pbe = pbe->next;
 340                         }
 341                 }
 342         }
 343         BUG_ON(pbe);
 344 }
 345
 346
 347 /**
 348  *      free_pagedir - free pages allocated with alloc_pagedir()
 349  */
 350
 351 static void free_pagedir(struct pbe *pblist, int clear_nosave_free)
 352 {
 353         struct pbe *pbe;
 354
 355         while (pblist) {
 356                 pbe = (pblist + PB_PAGE_SKIP)->next;
 357                 ClearPageNosave(virt_to_page(pblist));
 358                 if (clear_nosave_free)
 359                         ClearPageNosaveFree(virt_to_page(pblist));
 360                 free_page((unsigned long)pblist);
 361                 pblist = pbe;
 362         }
 363 }
 364
 365 /**
 366  *      fill_pb_page - Create a list of PBEs on a given memory page
 367  */
 368
 369 static inline void fill_pb_page(struct pbe *pbpage)
 370 {
 371         struct pbe *p;
 372
 373         p = pbpage;
 374         pbpage += PB_PAGE_SKIP;
 375         do
 376                 p->next = p + 1;
 377         while (++p < pbpage);
 378 }
 379
 380 /**
 381  *      create_pbe_list - Create a list of PBEs on top of a given chain
 382  *      of memory pages allocated with alloc_pagedir()
 383  */
 384
 385 static inline void create_pbe_list(struct pbe *pblist, unsigned int nr_pages)
 386 {
 387         struct pbe *pbpage, *p;
 388         unsigned int num = PBES_PER_PAGE;
 389
 390         for_each_pb_page (pbpage, pblist) {
 391                 if (num >= nr_pages)
 392                         break;
 393
 394                 fill_pb_page(pbpage);
 395                 num += PBES_PER_PAGE;
 396         }
 397         if (pbpage) {
 398                 for (num -= PBES_PER_PAGE - 1, p = pbpage; num < nr_pages; p++, num++)
 399                         p->next = p + 1;
 400                 p->next = NULL;
 401         }
 402 }
 403
 404 /**
 405  *      On resume it is necessary to trace and eventually free the unsafe
 406  *      pages that have been allocated, because they are needed for I/O
 407  *      (on x86-64 we likely will "eat" these pages once again while
 408  *      creating the temporary page translation tables)
 409  */
 410
 411 struct eaten_page {
 412         struct eaten_page *next;
 413         char padding[PAGE_SIZE - sizeof(void *)];
 414 };
 415
 416 static struct eaten_page *eaten_pages = NULL;
 417
 418 static void release_eaten_pages(void)
 419 {
 420         struct eaten_page *p, *q;
 421
 422         p = eaten_pages;
 423         while (p) {
 424                 q = p->next;
 425                 /* We don't want swsusp_free() to free this page again */
 426                 ClearPageNosave(virt_to_page(p));
 427                 free_page((unsigned long)p);
 428                 p = q;
 429         }
 430         eaten_pages = NULL;
 431 }
 432
 433 /**
 434  *      @safe_needed - on resume, for storing the PBE list and the image,
 435  *      we can only use memory pages that do not conflict with the pages
 436  *      which had been used before suspend.
 437  *
 438  *      The unsafe pages are marked with the PG_nosave_free flag
 439  *
 440  *      Allocated but unusable (ie eaten) memory pages should be marked
 441  *      so that swsusp_free() can release them
 442  */
 443
 444 static inline void *alloc_image_page(gfp_t gfp_mask, int safe_needed)
 445 {
 446         void *res;
 447
 448         if (safe_needed)
 449                 do {
 450                         res = (void *)get_zeroed_page(gfp_mask);
 451                         if (res && PageNosaveFree(virt_to_page(res))) {
 452                                 /* This is for swsusp_free() */
 453                                 SetPageNosave(virt_to_page(res));
 454                                 ((struct eaten_page *)res)->next = eaten_pages;
 455                                 eaten_pages = res;
 456                         }
 457                 } while (res && PageNosaveFree(virt_to_page(res)));
 458         else
 459                 res = (void *)get_zeroed_page(gfp_mask);
 460         if (res) {
 461                 SetPageNosave(virt_to_page(res));
 462                 SetPageNosaveFree(virt_to_page(res));
 463         }
 464         return res;
 465 }
 466
 467 unsigned long get_safe_page(gfp_t gfp_mask)
 468 {
 469         return (unsigned long)alloc_image_page(gfp_mask, 1);
 470 }
 471
 472 /**
 473  *      alloc_pagedir - Allocate the page directory.
 474  *
 475  *      First, determine exactly how many pages we need and
 476  *      allocate them.
 477  *
 478  *      We arrange the pages in a chain: each page is an array of PBES_PER_PAGE
 479  *      struct pbe elements (pbes) and the last element in the page points
 480  *      to the next page.
 481  *
 482  *      On each page we set up a list of struct_pbe elements.
 483  */
 484
 485 static struct pbe *alloc_pagedir(unsigned int nr_pages, gfp_t gfp_mask,
 486                                  int safe_needed)
 487 {
 488         unsigned int num;
 489         struct pbe *pblist, *pbe;
 490
 491         if (!nr_pages)
 492                 return NULL;
 493
 494         pblist = alloc_image_page(gfp_mask, safe_needed);
 495         /* FIXME: rewrite this ugly loop */
 496         for (pbe = pblist, num = PBES_PER_PAGE; pbe && num < nr_pages;
 497                         pbe = pbe->next, num += PBES_PER_PAGE) {
 498                 pbe += PB_PAGE_SKIP;
 499                 pbe->next = alloc_image_page(gfp_mask, safe_needed);
 500         }
 501         if (!pbe) { /* get_zeroed_page() failed */
 502                 free_pagedir(pblist, 1);
 503                 pblist = NULL;
 504         } else
 505                 create_pbe_list(pblist, nr_pages);
 506         return pblist;
 507 }
 508
 509 /**
 510  * Free pages we allocated for suspend. Suspend pages are alocated
 511  * before atomic copy, so we need to free them after resume.
 512  */
 513
 514 void swsusp_free(void)
 515 {
 516         struct zone *zone;
 517         unsigned long zone_pfn;
 518
 519         for_each_zone(zone) {
 520                 for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
 521                         if (pfn_valid(zone_pfn + zone->zone_start_pfn)) {
 522                                 struct page *page;
 523                                 page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
 524                                 if (PageNosave(page) && PageNosaveFree(page)) {
 525                                         ClearPageNosave(page);
 526                                         ClearPageNosaveFree(page);
 527                                         free_page((long) page_address(page));
 528                                 }
 529                         }
 530         }
 531         nr_copy_pages = 0;
 532         nr_meta_pages = 0;
 533         pagedir_nosave = NULL;
 534         buffer = NULL;
 535 }
 536
 537
 538 /**
 539  *      enough_free_mem - Make sure we enough free memory to snapshot.
 540  *
 541  *      Returns TRUE or FALSE after checking the number of available
 542  *      free pages.
 543  */
 544
 545 static int enough_free_mem(unsigned int nr_pages)
 546 {
 547         struct zone *zone;
 548         unsigned int n = 0;
 549
 550         for_each_zone (zone)
 551                 if (!is_highmem(zone))
 552                         n += zone->free_pages;
 553         pr_debug("swsusp: available memory: %u pages\n", n);
 554         return n > (nr_pages + PAGES_FOR_IO +
 555                 (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
 556 }
 557
 558 static int alloc_data_pages(struct pbe *pblist, gfp_t gfp_mask, int safe_needed)
 559 {
 560         struct pbe *p;
 561
 562         for_each_pbe (p, pblist) {
 563                 p->address = (unsigned long)alloc_image_page(gfp_mask, safe_needed);
 564                 if (!p->address)
 565                         return -ENOMEM;
 566         }
 567         return 0;
 568 }
 569
 570 static struct pbe *swsusp_alloc(unsigned int nr_pages)
 571 {
 572         struct pbe *pblist;
 573
 574         if (!(pblist = alloc_pagedir(nr_pages, GFP_ATOMIC | __GFP_COLD, 0))) {
 575                 printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
 576                 return NULL;
 577         }
 578
 579         if (alloc_data_pages(pblist, GFP_ATOMIC | __GFP_COLD, 0)) {
 580                 printk(KERN_ERR "suspend: Allocating image pages failed.\n");
 581                 swsusp_free();
 582                 return NULL;
 583         }
 584
 585         return pblist;
 586 }
 587
 588 asmlinkage int swsusp_save(void)
 589 {
 590         unsigned int nr_pages;
 591
 592         pr_debug("swsusp: critical section: \n");
 593
 594         drain_local_pages();
 595         nr_pages = count_data_pages();
 596         printk("swsusp: Need to copy %u pages\n", nr_pages);
 597
 598         pr_debug("swsusp: pages needed: %u + %lu + %u, free: %u\n",
 599                  nr_pages,
 600                  (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE,
 601                  PAGES_FOR_IO, nr_free_pages());
 602
 603         if (!enough_free_mem(nr_pages)) {
 604                 printk(KERN_ERR "swsusp: Not enough free memory\n");
 605                 return -ENOMEM;
 606         }
 607
 608         pagedir_nosave = swsusp_alloc(nr_pages);
 609         if (!pagedir_nosave)
 610                 return -ENOMEM;
 611
 612         /* During allocating of suspend pagedir, new cold pages may appear.
 613          * Kill them.
 614          */
 615         drain_local_pages();
 616         copy_data_pages(pagedir_nosave);
 617
 618         /*
 619          * End of critical section. From now on, we can write to memory,
 620          * but we should not touch disk. This specially means we must _not_
 621          * touch swap space! Except we must write out our image of course.
 622          */
 623
 624         nr_copy_pages = nr_pages;
 625         nr_meta_pages = (nr_pages * sizeof(long) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 626
 627         printk("swsusp: critical section/: done (%d pages copied)\n", nr_pages);
 628         return 0;
 629 }
 630
 631 static void init_header(struct swsusp_info *info)
 632 {
 633         memset(info, 0, sizeof(struct swsusp_info));
 634         info->version_code = LINUX_VERSION_CODE;
 635         info->num_physpages = num_physpages;
 636         memcpy(&info->uts, &system_utsname, sizeof(system_utsname));
 637         info->cpus = num_online_cpus();
 638         info->image_pages = nr_copy_pages;
 639         info->pages = nr_copy_pages + nr_meta_pages + 1;
 640         info->size = info->pages;
 641         info->size <<= PAGE_SHIFT;
 642 }
 643
 644 /**
 645  *      pack_orig_addresses - the .orig_address fields of the PBEs from the
 646  *      list starting at @pbe are stored in the array @buf[] (1 page)
 647  */
 648
 649 static inline struct pbe *pack_orig_addresses(unsigned long *buf, struct pbe *pbe)
 650 {
 651         int j;
 652
 653         for (j = 0; j < PAGE_SIZE / sizeof(long) && pbe; j++) {
 654                 buf[j] = pbe->orig_address;
 655                 pbe = pbe->next;
 656         }
 657         if (!pbe)
 658                 for (; j < PAGE_SIZE / sizeof(long); j++)
 659                         buf[j] = 0;
 660         return pbe;
 661 }
 662
 663 /**
 664  *      snapshot_read_next - used for reading the system memory snapshot.
 665  *
 666  *      On the first call to it @handle should point to a zeroed
 667  *      snapshot_handle structure.  The structure gets updated and a pointer
 668  *      to it should be passed to this function every next time.
 669  *
 670  *      The @count parameter should contain the number of bytes the caller
 671  *      wants to read from the snapshot.  It must not be zero.
 672  *
 673  *      On success the function returns a positive number.  Then, the caller
 674  *      is allowed to read up to the returned number of bytes from the memory
 675  *      location computed by the data_of() macro.  The number returned
 676  *      may be smaller than @count, but this only happens if the read would
 677  *      cross a page boundary otherwise.
 678  *
 679  *      The function returns 0 to indicate the end of data stream condition,
 680  *      and a negative number is returned on error.  In such cases the
 681  *      structure pointed to by @handle is not updated and should not be used
 682  *      any more.
 683  */
 684
 685 int snapshot_read_next(struct snapshot_handle *handle, size_t count)
 686 {
 687         if (handle->page > nr_meta_pages + nr_copy_pages)
 688                 return 0;
 689         if (!buffer) {
 690                 /* This makes the buffer be freed by swsusp_free() */
 691                 buffer = alloc_image_page(GFP_ATOMIC, 0);
 692                 if (!buffer)
 693                         return -ENOMEM;
 694         }
 695         if (!handle->offset) {
 696                 init_header((struct swsusp_info *)buffer);
 697                 handle->buffer = buffer;
 698                 handle->pbe = pagedir_nosave;
 699         }
 700         if (handle->prev < handle->page) {
 701                 if (handle->page <= nr_meta_pages) {
 702                         handle->pbe = pack_orig_addresses(buffer, handle->pbe);
 703                         if (!handle->pbe)
 704                                 handle->pbe = pagedir_nosave;
 705                 } else {
 706                         handle->buffer = (void *)handle->pbe->address;
 707                         handle->pbe = handle->pbe->next;
 708                 }
 709                 handle->prev = handle->page;
 710         }
 711         handle->buf_offset = handle->page_offset;
 712         if (handle->page_offset + count >= PAGE_SIZE) {
 713                 count = PAGE_SIZE - handle->page_offset;
 714                 handle->page_offset = 0;
 715                 handle->page++;
 716         } else {
 717                 handle->page_offset += count;
 718         }
 719         handle->offset += count;
 720         return count;
 721 }
 722
 723 /**
 724  *      mark_unsafe_pages - mark the pages that cannot be used for storing
 725  *      the image during resume, because they conflict with the pages that
 726  *      had been used before suspend
 727  */
 728
 729 static int mark_unsafe_pages(struct pbe *pblist)
 730 {
 731         struct zone *zone;
 732         unsigned long zone_pfn;
 733         struct pbe *p;
 734
 735         if (!pblist) /* a sanity check */
 736                 return -EINVAL;
 737
 738         /* Clear page flags */
 739         for_each_zone (zone) {
 740                 for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
 741                         if (pfn_valid(zone_pfn + zone->zone_start_pfn))
 742                                 ClearPageNosaveFree(pfn_to_page(zone_pfn +
 743                                         zone->zone_start_pfn));
 744         }
 745
 746         /* Mark orig addresses */
 747         for_each_pbe (p, pblist) {
 748                 if (virt_addr_valid(p->orig_address))
 749                         SetPageNosaveFree(virt_to_page(p->orig_address));
 750                 else
 751                         return -EFAULT;
 752         }
 753
 754         return 0;
 755 }
 756
 757 static void copy_page_backup_list(struct pbe *dst, struct pbe *src)
 758 {
 759         /* We assume both lists contain the same number of elements */
 760         while (src) {
 761                 dst->orig_address = src->orig_address;
 762                 dst = dst->next;
 763                 src = src->next;
 764         }
 765 }
 766
 767 static int check_header(struct swsusp_info *info)
 768 {
 769         char *reason = NULL;
 770
 771         if (info->version_code != LINUX_VERSION_CODE)
 772                 reason = "kernel version";
 773         if (info->num_physpages != num_physpages)
 774                 reason = "memory size";
 775         if (strcmp(info->uts.sysname,system_utsname.sysname))
 776                 reason = "system type";
 777         if (strcmp(info->uts.release,system_utsname.release))
 778                 reason = "kernel release";
 779         if (strcmp(info->uts.version,system_utsname.version))
 780                 reason = "version";
 781         if (strcmp(info->uts.machine,system_utsname.machine))
 782                 reason = "machine";
 783         if (reason) {
 784                 printk(KERN_ERR "swsusp: Resume mismatch: %s\n", reason);
 785                 return -EPERM;
 786         }
 787         return 0;
 788 }
 789
 790 /**
 791  *      load header - check the image header and copy data from it
 792  */
 793
 794 static int load_header(struct snapshot_handle *handle,
 795                               struct swsusp_info *info)
 796 {
 797         int error;
 798         struct pbe *pblist;
 799
 800         error = check_header(info);
 801         if (!error) {
 802                 pblist = alloc_pagedir(info->image_pages, GFP_ATOMIC, 0);
 803                 if (!pblist)
 804                         return -ENOMEM;
 805                 pagedir_nosave = pblist;
 806                 handle->pbe = pblist;
 807                 nr_copy_pages = info->image_pages;
 808                 nr_meta_pages = info->pages - info->image_pages - 1;
 809         }
 810         return error;
 811 }
 812
 813 /**
 814  *      unpack_orig_addresses - copy the elements of @buf[] (1 page) to
 815  *      the PBEs in the list starting at @pbe
 816  */
 817
 818 static inline struct pbe *unpack_orig_addresses(unsigned long *buf,
 819                                                 struct pbe *pbe)
 820 {
 821         int j;
 822
 823         for (j = 0; j < PAGE_SIZE / sizeof(long) && pbe; j++) {
 824                 pbe->orig_address = buf[j];
 825                 pbe = pbe->next;
 826         }
 827         return pbe;
 828 }
 829
 830 /**
 831  *      create_image - use metadata contained in the PBE list
 832  *      pointed to by pagedir_nosave to mark the pages that will
 833  *      be overwritten in the process of restoring the system
 834  *      memory state from the image and allocate memory for
 835  *      the image avoiding these pages
 836  */
 837
 838 static int create_image(struct snapshot_handle *handle)
 839 {
 840         int error = 0;
 841         struct pbe *p, *pblist;
 842
 843         p = pagedir_nosave;
 844         error = mark_unsafe_pages(p);
 845         if (!error) {
 846                 pblist = alloc_pagedir(nr_copy_pages, GFP_ATOMIC, 1);
 847                 if (pblist)
 848                         copy_page_backup_list(pblist, p);
 849                 free_pagedir(p, 0);
 850                 if (!pblist)
 851                         error = -ENOMEM;
 852         }
 853         if (!error)
 854                 error = alloc_data_pages(pblist, GFP_ATOMIC, 1);
 855         if (!error) {
 856                 release_eaten_pages();
 857                 pagedir_nosave = pblist;
 858         } else {
 859                 pagedir_nosave = NULL;
 860                 handle->pbe = NULL;
 861                 nr_copy_pages = 0;
 862                 nr_meta_pages = 0;
 863         }
 864         return error;
 865 }
 866
 867 /**
 868  *      snapshot_write_next - used for writing the system memory snapshot.
 869  *
 870  *      On the first call to it @handle should point to a zeroed
 871  *      snapshot_handle structure.  The structure gets updated and a pointer
 872  *      to it should be passed to this function every next time.
 873  *
 874  *      The @count parameter should contain the number of bytes the caller
 875  *      wants to write to the image.  It must not be zero.
 876  *
 877  *      On success the function returns a positive number.  Then, the caller
 878  *      is allowed to write up to the returned number of bytes to the memory
 879  *      location computed by the data_of() macro.  The number returned
 880  *      may be smaller than @count, but this only happens if the write would
 881  *      cross a page boundary otherwise.
 882  *
 883  *      The function returns 0 to indicate the "end of file" condition,
 884  *      and a negative number is returned on error.  In such cases the
 885  *      structure pointed to by @handle is not updated and should not be used
 886  *      any more.
 887  */
 888
 889 int snapshot_write_next(struct snapshot_handle *handle, size_t count)
 890 {
 891         int error = 0;
 892
 893         if (handle->prev && handle->page > nr_meta_pages + nr_copy_pages)
 894                 return 0;
 895         if (!buffer) {
 896                 /* This makes the buffer be freed by swsusp_free() */
 897                 buffer = alloc_image_page(GFP_ATOMIC, 0);
 898                 if (!buffer)
 899                         return -ENOMEM;
 900         }
 901         if (!handle->offset)
 902                 handle->buffer = buffer;
 903         if (handle->prev < handle->page) {
 904                 if (!handle->prev) {
 905                         error = load_header(handle, (struct swsusp_info *)buffer);
 906                         if (error)
 907                                 return error;
 908                 } else if (handle->prev <= nr_meta_pages) {
 909                         handle->pbe = unpack_orig_addresses(buffer, handle->pbe);
 910                         if (!handle->pbe) {
 911                                 error = create_image(handle);
 912                                 if (error)
 913                                         return error;
 914                                 handle->pbe = pagedir_nosave;
 915                                 handle->buffer = (void *)handle->pbe->address;
 916                         }
 917                 } else {
 918                         handle->pbe = handle->pbe->next;
 919                         handle->buffer = (void *)handle->pbe->address;
 920                 }
 921                 handle->prev = handle->page;
 922         }
 923         handle->buf_offset = handle->page_offset;
 924         if (handle->page_offset + count >= PAGE_SIZE) {
 925                 count = PAGE_SIZE - handle->page_offset;
 926                 handle->page_offset = 0;
 927                 handle->page++;
 928         } else {
 929                 handle->page_offset += count;
 930         }
 931         handle->offset += count;
 932         return count;
 933 }
 934
 935 int snapshot_image_loaded(struct snapshot_handle *handle)
 936 {
 937         return !(!handle->pbe || handle->pbe->next || !nr_copy_pages ||
 938                 handle->page <= nr_meta_pages + nr_copy_pages);
 939 }