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