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e820_32.c

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/ioport.h>
#include <linux/string.h>
#include <linux/kexec.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/efi.h>
#include <linux/pfn.h>
#include <linux/uaccess.h>
#include <linux/suspend.h>

#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/e820.h>
#include <asm/setup.h>

#ifdef CONFIG_EFI
int efi_enabled = 0;
EXPORT_SYMBOL(efi_enabled);
#endif

struct e820map e820;
struct change_member {
      struct e820entry *pbios; /* pointer to original bios entry */
      unsigned long long addr; /* address for this change point */
};
static struct change_member change_point_list[2*E820MAX] __initdata;
static struct change_member *change_point[2*E820MAX] __initdata;
static struct e820entry *overlap_list[E820MAX] __initdata;
static struct e820entry new_bios[E820MAX] __initdata;
/* For PCI or other memory-mapped resources */
unsigned long pci_mem_start = 0x10000000;
#ifdef CONFIG_PCI
EXPORT_SYMBOL(pci_mem_start);
#endif
extern int user_defined_memmap;
struct resource data_resource = {
      .name = "Kernel data",
      .start      = 0,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_MEM
};

struct resource code_resource = {
      .name = "Kernel code",
      .start      = 0,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_MEM
};

struct resource bss_resource = {
      .name = "Kernel bss",
      .start      = 0,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_MEM
};

static struct resource system_rom_resource = {
      .name = "System ROM",
      .start      = 0xf0000,
      .end  = 0xfffff,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

static struct resource extension_rom_resource = {
      .name = "Extension ROM",
      .start      = 0xe0000,
      .end  = 0xeffff,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

static struct resource adapter_rom_resources[] = { {
      .name       = "Adapter ROM",
      .start      = 0xc8000,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
      .name       = "Adapter ROM",
      .start      = 0,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
      .name       = "Adapter ROM",
      .start      = 0,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
      .name       = "Adapter ROM",
      .start      = 0,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
      .name       = "Adapter ROM",
      .start      = 0,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
      .name       = "Adapter ROM",
      .start      = 0,
      .end  = 0,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
} };

static struct resource video_rom_resource = {
      .name       = "Video ROM",
      .start      = 0xc0000,
      .end  = 0xc7fff,
      .flags      = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};

static struct resource video_ram_resource = {
      .name = "Video RAM area",
      .start      = 0xa0000,
      .end  = 0xbffff,
      .flags      = IORESOURCE_BUSY | IORESOURCE_MEM
};

static struct resource standard_io_resources[] = { {
      .name = "dma1",
      .start      = 0x0000,
      .end  = 0x001f,
      .flags      = IORESOURCE_BUSY | IORESOURCE_IO
}, {
      .name = "pic1",
      .start      = 0x0020,
      .end  = 0x0021,
      .flags      = IORESOURCE_BUSY | IORESOURCE_IO
}, {
      .name   = "timer0",
      .start      = 0x0040,
      .end    = 0x0043,
      .flags  = IORESOURCE_BUSY | IORESOURCE_IO
}, {
      .name   = "timer1",
      .start  = 0x0050,
      .end    = 0x0053,
      .flags      = IORESOURCE_BUSY | IORESOURCE_IO
}, {
      .name = "keyboard",
      .start      = 0x0060,
      .end  = 0x006f,
      .flags      = IORESOURCE_BUSY | IORESOURCE_IO
}, {
      .name = "dma page reg",
      .start      = 0x0080,
      .end  = 0x008f,
      .flags      = IORESOURCE_BUSY | IORESOURCE_IO
}, {
      .name = "pic2",
      .start      = 0x00a0,
      .end  = 0x00a1,
      .flags      = IORESOURCE_BUSY | IORESOURCE_IO
}, {
      .name = "dma2",
      .start      = 0x00c0,
      .end  = 0x00df,
      .flags      = IORESOURCE_BUSY | IORESOURCE_IO
}, {
      .name = "fpu",
      .start      = 0x00f0,
      .end  = 0x00ff,
      .flags      = IORESOURCE_BUSY | IORESOURCE_IO
} };

#define ROMSIGNATURE 0xaa55

static int __init romsignature(const unsigned char *rom)
{
      const unsigned short * const ptr = (const unsigned short *)rom;
      unsigned short sig;

      return probe_kernel_address(ptr, sig) == 0 && sig == ROMSIGNATURE;
}

static int __init romchecksum(const unsigned char *rom, unsigned long length)
{
      unsigned char sum, c;

      for (sum = 0; length && probe_kernel_address(rom++, c) == 0; length--)
            sum += c;
      return !length && !sum;
}

static void __init probe_roms(void)
{
      const unsigned char *rom;
      unsigned long start, length, upper;
      unsigned char c;
      int i;

      /* video rom */
      upper = adapter_rom_resources[0].start;
      for (start = video_rom_resource.start; start < upper; start += 2048) {
            rom = isa_bus_to_virt(start);
            if (!romsignature(rom))
                  continue;

            video_rom_resource.start = start;

            if (probe_kernel_address(rom + 2, c) != 0)
                  continue;

            /* 0 < length <= 0x7f * 512, historically */
            length = c * 512;

            /* if checksum okay, trust length byte */
            if (length && romchecksum(rom, length))
                  video_rom_resource.end = start + length - 1;

            request_resource(&iomem_resource, &video_rom_resource);
            break;
      }

      start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
      if (start < upper)
            start = upper;

      /* system rom */
      request_resource(&iomem_resource, &system_rom_resource);
      upper = system_rom_resource.start;

      /* check for extension rom (ignore length byte!) */
      rom = isa_bus_to_virt(extension_rom_resource.start);
      if (romsignature(rom)) {
            length = extension_rom_resource.end - extension_rom_resource.start + 1;
            if (romchecksum(rom, length)) {
                  request_resource(&iomem_resource, &extension_rom_resource);
                  upper = extension_rom_resource.start;
            }
      }

      /* check for adapter roms on 2k boundaries */
      for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
            rom = isa_bus_to_virt(start);
            if (!romsignature(rom))
                  continue;

            if (probe_kernel_address(rom + 2, c) != 0)
                  continue;

            /* 0 < length <= 0x7f * 512, historically */
            length = c * 512;

            /* but accept any length that fits if checksum okay */
            if (!length || start + length > upper || !romchecksum(rom, length))
                  continue;

            adapter_rom_resources[i].start = start;
            adapter_rom_resources[i].end = start + length - 1;
            request_resource(&iomem_resource, &adapter_rom_resources[i]);

            start = adapter_rom_resources[i++].end & ~2047UL;
      }
}

/*
 * Request address space for all standard RAM and ROM resources
 * and also for regions reported as reserved by the e820.
 */
static void __init
legacy_init_iomem_resources(struct resource *code_resource,
                      struct resource *data_resource,
                      struct resource *bss_resource)
{
      int i;

      probe_roms();
      for (i = 0; i < e820.nr_map; i++) {
            struct resource *res;
#ifndef CONFIG_RESOURCES_64BIT
            if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
                  continue;
#endif
            res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
            switch (e820.map[i].type) {
            case E820_RAM:    res->name = "System RAM"; break;
            case E820_ACPI:   res->name = "ACPI Tables"; break;
            case E820_NVS:    res->name = "ACPI Non-volatile Storage"; break;
            default:    res->name = "reserved";
            }
            res->start = e820.map[i].addr;
            res->end = res->start + e820.map[i].size - 1;
            res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
            if (request_resource(&iomem_resource, res)) {
                  kfree(res);
                  continue;
            }
            if (e820.map[i].type == E820_RAM) {
                  /*
                   *  We don't know which RAM region contains kernel data,
                   *  so we try it repeatedly and let the resource manager
                   *  test it.
                   */
                  request_resource(res, code_resource);
                  request_resource(res, data_resource);
                  request_resource(res, bss_resource);
#ifdef CONFIG_KEXEC
                  if (crashk_res.start != crashk_res.end)
                        request_resource(res, &crashk_res);
#endif
            }
      }
}

/*
 * Request address space for all standard resources
 *
 * This is called just before pcibios_init(), which is also a
 * subsys_initcall, but is linked in later (in arch/i386/pci/common.c).
 */
static int __init request_standard_resources(void)
{
      int i;

      printk("Setting up standard PCI resources\n");
      if (efi_enabled)
            efi_initialize_iomem_resources(&code_resource,
                        &data_resource, &bss_resource);
      else
            legacy_init_iomem_resources(&code_resource,
                        &data_resource, &bss_resource);

      /* EFI systems may still have VGA */
      request_resource(&iomem_resource, &video_ram_resource);

      /* request I/O space for devices used on all i[345]86 PCs */
      for (i = 0; i < ARRAY_SIZE(standard_io_resources); i++)
            request_resource(&ioport_resource, &standard_io_resources[i]);
      return 0;
}

subsys_initcall(request_standard_resources);

#if defined(CONFIG_PM) && defined(CONFIG_HIBERNATION)
/**
 * e820_mark_nosave_regions - Find the ranges of physical addresses that do not
 * correspond to e820 RAM areas and mark the corresponding pages as nosave for
 * hibernation.
 *
 * This function requires the e820 map to be sorted and without any
 * overlapping entries and assumes the first e820 area to be RAM.
 */
void __init e820_mark_nosave_regions(void)
{
      int i;
      unsigned long pfn;

      pfn = PFN_DOWN(e820.map[0].addr + e820.map[0].size);
      for (i = 1; i < e820.nr_map; i++) {
            struct e820entry *ei = &e820.map[i];

            if (pfn < PFN_UP(ei->addr))
                  register_nosave_region(pfn, PFN_UP(ei->addr));

            pfn = PFN_DOWN(ei->addr + ei->size);
            if (ei->type != E820_RAM)
                  register_nosave_region(PFN_UP(ei->addr), pfn);

            if (pfn >= max_low_pfn)
                  break;
      }
}
#endif

void __init add_memory_region(unsigned long long start,
                        unsigned long long size, int type)
{
      int x;

      if (!efi_enabled) {
                  x = e820.nr_map;

            if (x == E820MAX) {
                printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
                return;
            }

            e820.map[x].addr = start;
            e820.map[x].size = size;
            e820.map[x].type = type;
            e820.nr_map++;
      }
} /* add_memory_region */

/*
 * Sanitize the BIOS e820 map.
 *
 * Some e820 responses include overlapping entries.  The following
 * replaces the original e820 map with a new one, removing overlaps.
 *
 */
int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
{
      struct change_member *change_tmp;
      unsigned long current_type, last_type;
      unsigned long long last_addr;
      int chgidx, still_changing;
      int overlap_entries;
      int new_bios_entry;
      int old_nr, new_nr, chg_nr;
      int i;

      /*
            Visually we're performing the following (1,2,3,4 = memory types)...

            Sample memory map (w/overlaps):
               ____22__________________
               ______________________4_
               ____1111________________
               _44_____________________
               11111111________________
               ____________________33__
               ___________44___________
               __________33333_________
               ______________22________
               ___________________2222_
               _________111111111______
               _____________________11_
               _________________4______

            Sanitized equivalent (no overlap):
               1_______________________
               _44_____________________
               ___1____________________
               ____22__________________
               ______11________________
               _________1______________
               __________3_____________
               ___________44___________
               _____________33_________
               _______________2________
               ________________1_______
               _________________4______
               ___________________2____
               ____________________33__
               ______________________4_
      */
      /* if there's only one memory region, don't bother */
      if (*pnr_map < 2) {
            return -1;
      }

      old_nr = *pnr_map;

      /* bail out if we find any unreasonable addresses in bios map */
      for (i=0; i<old_nr; i++)
            if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr) {
                  return -1;
            }

      /* create pointers for initial change-point information (for sorting) */
      for (i=0; i < 2*old_nr; i++)
            change_point[i] = &change_point_list[i];

      /* record all known change-points (starting and ending addresses),
         omitting those that are for empty memory regions */
      chgidx = 0;
      for (i=0; i < old_nr; i++)    {
            if (biosmap[i].size != 0) {
                  change_point[chgidx]->addr = biosmap[i].addr;
                  change_point[chgidx++]->pbios = &biosmap[i];
                  change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
                  change_point[chgidx++]->pbios = &biosmap[i];
            }
      }
      chg_nr = chgidx;        /* true number of change-points */

      /* sort change-point list by memory addresses (low -> high) */
      still_changing = 1;
      while (still_changing)  {
            still_changing = 0;
            for (i=1; i < chg_nr; i++)  {
                  /* if <current_addr> > <last_addr>, swap */
                  /* or, if current=<start_addr> & last=<end_addr>, swap */
                  if ((change_point[i]->addr < change_point[i-1]->addr) ||
                        ((change_point[i]->addr == change_point[i-1]->addr) &&
                         (change_point[i]->addr == change_point[i]->pbios->addr) &&
                         (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
                     )
                  {
                        change_tmp = change_point[i];
                        change_point[i] = change_point[i-1];
                        change_point[i-1] = change_tmp;
                        still_changing=1;
                  }
            }
      }

      /* create a new bios memory map, removing overlaps */
      overlap_entries=0;       /* number of entries in the overlap table */
      new_bios_entry=0;  /* index for creating new bios map entries */
      last_type = 0;           /* start with undefined memory type */
      last_addr = 0;           /* start with 0 as last starting address */
      /* loop through change-points, determining affect on the new bios map */
      for (chgidx=0; chgidx < chg_nr; chgidx++)
      {
            /* keep track of all overlapping bios entries */
            if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
            {
                  /* add map entry to overlap list (> 1 entry implies an overlap) */
                  overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
            }
            else
            {
                  /* remove entry from list (order independent, so swap with last) */
                  for (i=0; i<overlap_entries; i++)
                  {
                        if (overlap_list[i] == change_point[chgidx]->pbios)
                              overlap_list[i] = overlap_list[overlap_entries-1];
                  }
                  overlap_entries--;
            }
            /* if there are overlapping entries, decide which "type" to use */
            /* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
            current_type = 0;
            for (i=0; i<overlap_entries; i++)
                  if (overlap_list[i]->type > current_type)
                        current_type = overlap_list[i]->type;
            /* continue building up new bios map based on this information */
            if (current_type != last_type)      {
                  if (last_type != 0)      {
                        new_bios[new_bios_entry].size =
                              change_point[chgidx]->addr - last_addr;
                        /* move forward only if the new size was non-zero */
                        if (new_bios[new_bios_entry].size != 0)
                              if (++new_bios_entry >= E820MAX)
                                    break;      /* no more space left for new bios entries */
                  }
                  if (current_type != 0)  {
                        new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
                        new_bios[new_bios_entry].type = current_type;
                        last_addr=change_point[chgidx]->addr;
                  }
                  last_type = current_type;
            }
      }
      new_nr = new_bios_entry;   /* retain count for new bios entries */

      /* copy new bios mapping into original location */
      memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
      *pnr_map = new_nr;

      return 0;
}

/*
 * Copy the BIOS e820 map into a safe place.
 *
 * Sanity-check it while we're at it..
 *
 * If we're lucky and live on a modern system, the setup code
 * will have given us a memory map that we can use to properly
 * set up memory.  If we aren't, we'll fake a memory map.
 *
 * We check to see that the memory map contains at least 2 elements
 * before we'll use it, because the detection code in setup.S may
 * not be perfect and most every PC known to man has two memory
 * regions: one from 0 to 640k, and one from 1mb up.  (The IBM
 * thinkpad 560x, for example, does not cooperate with the memory
 * detection code.)
 */
int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
{
      /* Only one memory region (or negative)? Ignore it */
      if (nr_map < 2)
            return -1;

      do {
            unsigned long long start = biosmap->addr;
            unsigned long long size = biosmap->size;
            unsigned long long end = start + size;
            unsigned long type = biosmap->type;

            /* Overflow in 64 bits? Ignore the memory map. */
            if (start > end)
                  return -1;

            /*
             * Some BIOSes claim RAM in the 640k - 1M region.
             * Not right. Fix it up.
             */
            if (type == E820_RAM) {
                  if (start < 0x100000ULL && end > 0xA0000ULL) {
                        if (start < 0xA0000ULL)
                              add_memory_region(start, 0xA0000ULL-start, type);
                        if (end <= 0x100000ULL)
                              continue;
                        start = 0x100000ULL;
                        size = end - start;
                  }
            }
            add_memory_region(start, size, type);
      } while (biosmap++,--nr_map);
      return 0;
}

/*
 * Callback for efi_memory_walk.
 */
static int __init
efi_find_max_pfn(unsigned long start, unsigned long end, void *arg)
{
      unsigned long *max_pfn = arg, pfn;

      if (start < end) {
            pfn = PFN_UP(end -1);
            if (pfn > *max_pfn)
                  *max_pfn = pfn;
      }
      return 0;
}

static int __init
efi_memory_present_wrapper(unsigned long start, unsigned long end, void *arg)
{
      memory_present(0, PFN_UP(start), PFN_DOWN(end));
      return 0;
}

/*
 * Find the highest page frame number we have available
 */
void __init find_max_pfn(void)
{
      int i;

      max_pfn = 0;
      if (efi_enabled) {
            efi_memmap_walk(efi_find_max_pfn, &max_pfn);
            efi_memmap_walk(efi_memory_present_wrapper, NULL);
            return;
      }

      for (i = 0; i < e820.nr_map; i++) {
            unsigned long start, end;
            /* RAM? */
            if (e820.map[i].type != E820_RAM)
                  continue;
            start = PFN_UP(e820.map[i].addr);
            end = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
            if (start >= end)
                  continue;
            if (end > max_pfn)
                  max_pfn = end;
            memory_present(0, start, end);
      }
}

/*
 * Free all available memory for boot time allocation.  Used
 * as a callback function by efi_memory_walk()
 */

static int __init
free_available_memory(unsigned long start, unsigned long end, void *arg)
{
      /* check max_low_pfn */
      if (start >= (max_low_pfn << PAGE_SHIFT))
            return 0;
      if (end >= (max_low_pfn << PAGE_SHIFT))
            end = max_low_pfn << PAGE_SHIFT;
      if (start < end)
            free_bootmem(start, end - start);

      return 0;
}
/*
 * Register fully available low RAM pages with the bootmem allocator.
 */
void __init register_bootmem_low_pages(unsigned long max_low_pfn)
{
      int i;

      if (efi_enabled) {
            efi_memmap_walk(free_available_memory, NULL);
            return;
      }
      for (i = 0; i < e820.nr_map; i++) {
            unsigned long curr_pfn, last_pfn, size;
            /*
             * Reserve usable low memory
             */
            if (e820.map[i].type != E820_RAM)
                  continue;
            /*
             * We are rounding up the start address of usable memory:
             */
            curr_pfn = PFN_UP(e820.map[i].addr);
            if (curr_pfn >= max_low_pfn)
                  continue;
            /*
             * ... and at the end of the usable range downwards:
             */
            last_pfn = PFN_DOWN(e820.map[i].addr + e820.map[i].size);

            if (last_pfn > max_low_pfn)
                  last_pfn = max_low_pfn;

            /*
             * .. finally, did all the rounding and playing
             * around just make the area go away?
             */
            if (last_pfn <= curr_pfn)
                  continue;

            size = last_pfn - curr_pfn;
            free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
      }
}

void __init e820_register_memory(void)
{
      unsigned long gapstart, gapsize, round;
      unsigned long long last;
      int i;

      /*
       * Search for the biggest gap in the low 32 bits of the e820
       * memory space.
       */
      last = 0x100000000ull;
      gapstart = 0x10000000;
      gapsize = 0x400000;
      i = e820.nr_map;
      while (--i >= 0) {
            unsigned long long start = e820.map[i].addr;
            unsigned long long end = start + e820.map[i].size;

            /*
             * Since "last" is at most 4GB, we know we'll
             * fit in 32 bits if this condition is true
             */
            if (last > end) {
                  unsigned long gap = last - end;

                  if (gap > gapsize) {
                        gapsize = gap;
                        gapstart = end;
                  }
            }
            if (start < last)
                  last = start;
      }

      /*
       * See how much we want to round up: start off with
       * rounding to the next 1MB area.
       */
      round = 0x100000;
      while ((gapsize >> 4) > round)
            round += round;
      /* Fun with two's complement */
      pci_mem_start = (gapstart + round) & -round;

      printk("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
            pci_mem_start, gapstart, gapsize);
}

void __init print_memory_map(char *who)
{
      int i;

      for (i = 0; i < e820.nr_map; i++) {
            printk(" %s: %016Lx - %016Lx ", who,
                  e820.map[i].addr,
                  e820.map[i].addr + e820.map[i].size);
            switch (e820.map[i].type) {
            case E820_RAM:    printk("(usable)\n");
                        break;
            case E820_RESERVED:
                        printk("(reserved)\n");
                        break;
            case E820_ACPI:
                        printk("(ACPI data)\n");
                        break;
            case E820_NVS:
                        printk("(ACPI NVS)\n");
                        break;
            default:    printk("type %u\n", e820.map[i].type);
                        break;
            }
      }
}

static __init __always_inline void efi_limit_regions(unsigned long long size)
{
      unsigned long long current_addr = 0;
      efi_memory_desc_t *md, *next_md;
      void *p, *p1;
      int i, j;

      j = 0;
      p1 = memmap.map;
      for (p = p1, i = 0; p < memmap.map_end; p += memmap.desc_size, i++) {
            md = p;
            next_md = p1;
            current_addr = md->phys_addr +
                  PFN_PHYS(md->num_pages);
            if (is_available_memory(md)) {
                  if (md->phys_addr >= size) continue;
                  memcpy(next_md, md, memmap.desc_size);
                  if (current_addr >= size) {
                        next_md->num_pages -=
                              PFN_UP(current_addr-size);
                  }
                  p1 += memmap.desc_size;
                  next_md = p1;
                  j++;
            } else if ((md->attribute & EFI_MEMORY_RUNTIME) ==
                     EFI_MEMORY_RUNTIME) {
                  /* In order to make runtime services
                   * available we have to include runtime
                   * memory regions in memory map */
                  memcpy(next_md, md, memmap.desc_size);
                  p1 += memmap.desc_size;
                  next_md = p1;
                  j++;
            }
      }
      memmap.nr_map = j;
      memmap.map_end = memmap.map +
            (memmap.nr_map * memmap.desc_size);
}

void __init limit_regions(unsigned long long size)
{
      unsigned long long current_addr;
      int i;

      print_memory_map("limit_regions start");
      if (efi_enabled) {
            efi_limit_regions(size);
            return;
      }
      for (i = 0; i < e820.nr_map; i++) {
            current_addr = e820.map[i].addr + e820.map[i].size;
            if (current_addr < size)
                  continue;

            if (e820.map[i].type != E820_RAM)
                  continue;

            if (e820.map[i].addr >= size) {
                  /*
                   * This region starts past the end of the
                   * requested size, skip it completely.
                   */
                  e820.nr_map = i;
            } else {
                  e820.nr_map = i + 1;
                  e820.map[i].size -= current_addr - size;
            }
            print_memory_map("limit_regions endfor");
            return;
      }
      print_memory_map("limit_regions endfunc");
}

/*
 * This function checks if any part of the range <start,end> is mapped
 * with type.
 */
int
e820_any_mapped(u64 start, u64 end, unsigned type)
{
      int i;
      for (i = 0; i < e820.nr_map; i++) {
            const struct e820entry *ei = &e820.map[i];
            if (type && ei->type != type)
                  continue;
            if (ei->addr >= end || ei->addr + ei->size <= start)
                  continue;
            return 1;
      }
      return 0;
}
EXPORT_SYMBOL_GPL(e820_any_mapped);

 /*
  * This function checks if the entire range <start,end> is mapped with type.
  *
  * Note: this function only works correct if the e820 table is sorted and
  * not-overlapping, which is the case
  */
int __init
e820_all_mapped(unsigned long s, unsigned long e, unsigned type)
{
      u64 start = s;
      u64 end = e;
      int i;
      for (i = 0; i < e820.nr_map; i++) {
            struct e820entry *ei = &e820.map[i];
            if (type && ei->type != type)
                  continue;
            /* is the region (part) in overlap with the current region ?*/
            if (ei->addr >= end || ei->addr + ei->size <= start)
                  continue;
            /* if the region is at the beginning of <start,end> we move
             * start to the end of the region since it's ok until there
             */
            if (ei->addr <= start)
                  start = ei->addr + ei->size;
            /* if start is now at or beyond end, we're done, full
             * coverage */
            if (start >= end)
                  return 1; /* we're done */
      }
      return 0;
}

static int __init parse_memmap(char *arg)
{
      if (!arg)
            return -EINVAL;

      if (strcmp(arg, "exactmap") == 0) {
#ifdef CONFIG_CRASH_DUMP
            /* If we are doing a crash dump, we
             * still need to know the real mem
             * size before original memory map is
             * reset.
             */
            find_max_pfn();
            saved_max_pfn = max_pfn;
#endif
            e820.nr_map = 0;
            user_defined_memmap = 1;
      } else {
            /* If the user specifies memory size, we
             * limit the BIOS-provided memory map to
             * that size. exactmap can be used to specify
             * the exact map. mem=number can be used to
             * trim the existing memory map.
             */
            unsigned long long start_at, mem_size;

            mem_size = memparse(arg, &arg);
            if (*arg == '@') {
                  start_at = memparse(arg+1, &arg);
                  add_memory_region(start_at, mem_size, E820_RAM);
            } else if (*arg == '#') {
                  start_at = memparse(arg+1, &arg);
                  add_memory_region(start_at, mem_size, E820_ACPI);
            } else if (*arg == '$') {
                  start_at = memparse(arg+1, &arg);
                  add_memory_region(start_at, mem_size, E820_RESERVED);
            } else {
                  limit_regions(mem_size);
                  user_defined_memmap = 1;
            }
      }
      return 0;
}
early_param("memmap", parse_memmap);

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