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