/*
 * Handle the memory map.
 * The functions here do the job until bootmem takes over.
 *
 *  Getting sanitize_e820_map() in sync with i386 version by applying change:
 *  -  Provisions for empty E820 memory regions (reported by certain BIOSes).
 *     Alex Achenbach <xela@slit.de>, December 2002.
 *  Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
 *
 */
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/crash_dump.h>
#include <linux/export.h>
#include <linux/bootmem.h>
#include <linux/pfn.h>
#include <linux/suspend.h>
#include <linux/acpi.h>
#include <linux/firmware-map.h>
#include <linux/memblock.h>
#include <linux/sort.h>

#include <asm/e820.h>
#include <asm/proto.h>
#include <asm/setup.h>

/*
 * The e820 map is the map that gets modified e.g. with command line parameters
 * and that is also registered with modifications in the kernel resource tree
 * with the iomem_resource as parent.
 *
 * The e820_saved is directly saved after the BIOS-provided memory map is
 * copied. It doesn't get modified afterwards. It's registered for the
 * /sys/firmware/memmap interface.
 *
 * That memory map is not modified and is used as base for kexec. The kexec'd
 * kernel should get the same memory map as the firmware provides. Then the
 * user can e.g. boot the original kernel with mem=1G while still booting the
 * next kernel with full memory.
 */
struct e820map e820;
struct e820map e820_saved;

/* For PCI or other memory-mapped resources */
unsigned long pci_mem_start = 0xaeedbabe;
#ifdef CONFIG_PCI
EXPORT_SYMBOL(pci_mem_start);
#endif

/*
 * 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++) {
                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(u64 start, u64 end, unsigned type)
{
        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;
        }
        return 0;
}

/*
 * Add a memory region to the kernel e820 map.
 */
static void __init __e820_add_region(struct e820map *e820x, u64 start, u64 size,
                                         int type)
{
        int x = e820x->nr_map;

        if (x >= ARRAY_SIZE(e820x->map)) {
                printk(KERN_ERR "e820: too many entries; ignoring [mem %#010llx-%#010llx]\n",
                       (unsigned long long) start,
                       (unsigned long long) (start + size - 1));
                return;
        }

        e820x->map[x].addr = start;
        e820x->map[x].size = size;
        e820x->map[x].type = type;
        e820x->nr_map++;
}

void __init e820_add_region(u64 start, u64 size, int type)
{
        __e820_add_region(&e820, start, size, type);
}

static void __init e820_print_type(u32 type)
{
        switch (type) {
        case E820_RAM:
        case E820_RESERVED_KERN:
                printk(KERN_CONT "usable");
                break;
        case E820_RESERVED:
                printk(KERN_CONT "reserved");
                break;
        case E820_ACPI:
                printk(KERN_CONT "ACPI data");
                break;
        case E820_NVS:
                printk(KERN_CONT "ACPI NVS");
                break;
        case E820_UNUSABLE:
                printk(KERN_CONT "unusable");
                break;
        default:
                printk(KERN_CONT "type %u", type);
                break;
        }
}

void __init e820_print_map(char *who)
{
        int i;

        for (i = 0; i < e820.nr_map; i++) {
                printk(KERN_INFO "%s: [mem %#018Lx-%#018Lx] ", who,
                       (unsigned long long) e820.map[i].addr,
                       (unsigned long long)
                       (e820.map[i].addr + e820.map[i].size - 1));
                e820_print_type(e820.map[i].type);
                printk(KERN_CONT "\n");
        }
}

/*
 * Sanitize the BIOS e820 map.
 *
 * Some e820 responses include overlapping entries. The following
 * replaces the original e820 map with a new one, removing overlaps,
 * and resolving conflicting memory types in favor of highest
 * numbered type.
 *
 * The input parameter biosmap points to an array of 'struct
 * e820entry' which on entry has elements in the range [0, *pnr_map)
 * valid, and which has space for up to max_nr_map entries.
 * On return, the resulting sanitized e820 map entries will be in
 * overwritten in the same location, starting at biosmap.
 *
 * The integer pointed to by pnr_map must be valid on entry (the
 * current number of valid entries located at biosmap). If the
 * sanitizing succeeds the *pnr_map will be updated with the new
 * number of valid entries (something no more than max_nr_map).
 *
 * The return value from sanitize_e820_map() is zero if it
 * successfully 'sanitized' the map entries passed in, and is -1
 * if it did nothing, which can happen if either of (1) it was
 * only passed one map entry, or (2) any of the input map entries
 * were invalid (start + size < start, meaning that the size was
 * so big the described memory range wrapped around through zero.)
 *
 *      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_
 */
struct change_member {
        struct e820entry *pbios; /* pointer to original bios entry */
        unsigned long long addr; /* address for this change point */
};

static int __init cpcompare(const void *a, const void *b)
{
        struct change_member * const *app = a, * const *bpp = b;
        const struct change_member *ap = *app, *bp = *bpp;

        /*
         * Inputs are pointers to two elements of change_point[].  If their
         * addresses are unequal, their difference dominates.  If the addresses
         * are equal, then consider one that represents the end of its region
         * to be greater than one that does not.
         */
        if (ap->addr != bp->addr)
                return ap->addr > bp->addr ? 1 : -1;

        return (ap->addr != ap->pbios->addr) - (bp->addr != bp->pbios->addr);
}

int __init sanitize_e820_map(struct e820entry *biosmap, int max_nr_map,
                             u32 *pnr_map)
{
        static struct change_member change_point_list[2*E820_X_MAX] __initdata;
        static struct change_member *change_point[2*E820_X_MAX] __initdata;
        static struct e820entry *overlap_list[E820_X_MAX] __initdata;
        static struct e820entry new_bios[E820_X_MAX] __initdata;
        unsigned long current_type, last_type;
        unsigned long long last_addr;
        int chgidx;
        int overlap_entries;
        int new_bios_entry;
        int old_nr, new_nr, chg_nr;
        int i;

        /* if there's only one memory region, don't bother */
        if (*pnr_map < 2)
                return -1;

        old_nr = *pnr_map;
        BUG_ON(old_nr > max_nr_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;

        /* sort change-point list by memory addresses (low -> high) */
        sort(change_point, chg_nr, sizeof *change_point, cpcompare, NULL);

        /* 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)
                                        /*
                                         * no more space left for new
                                         * bios entries ?
                                         */
                                        if (++new_bios_entry >= max_nr_map)
                                                break;
                        }
                        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;
                }
        }
        /* retain count for new bios entries */
        new_nr = new_bios_entry;

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

        return 0;
}

static int __init __append_e820_map(struct e820entry *biosmap, int nr_map)
{
        while (nr_map) {
                u64 start = biosmap->addr;
                u64 size = biosmap->size;
                u64 end = start + size;
                u32 type = biosmap->type;

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

                e820_add_region(start, size, type);

                biosmap++;
                nr_map--;
        }
        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.
 */
static int __init append_e820_map(struct e820entry *biosmap, int nr_map)
{
        /* Only one memory region (or negative)? Ignore it */
        if (nr_map < 2)
                return -1;

        return __append_e820_map(biosmap, nr_map);
}

static u64 __init __e820_update_range(struct e820map *e820x, u64 start,
                                        u64 size, unsigned old_type,
                                        unsigned new_type)
{
        u64 end;
        unsigned int i;
        u64 real_updated_size = 0;

        BUG_ON(old_type == new_type);

        if (size > (ULLONG_MAX - start))
                size = ULLONG_MAX - start;

        end = start + size;
        printk(KERN_DEBUG "e820: update [mem %#010Lx-%#010Lx] ",
               (unsigned long long) start, (unsigned long long) (end - 1));
        e820_print_type(old_type);
        printk(KERN_CONT " ==> ");
        e820_print_type(new_type);
        printk(KERN_CONT "\n");

        for (i = 0; i < e820x->nr_map; i++) {
                struct e820entry *ei = &e820x->map[i];
                u64 final_start, final_end;
                u64 ei_end;

                if (ei->type != old_type)
                        continue;

                ei_end = ei->addr + ei->size;
                /* totally covered by new range? */
                if (ei->addr >= start && ei_end <= end) {
                        ei->type = new_type;
                        real_updated_size += ei->size;
                        continue;
                }

                /* new range is totally covered? */
                if (ei->addr < start && ei_end > end) {
                        __e820_add_region(e820x, start, size, new_type);
                        __e820_add_region(e820x, end, ei_end - end, ei->type);
                        ei->size = start - ei->addr;
                        real_updated_size += size;
                        continue;
                }

                /* partially covered */
                final_start = max(start, ei->addr);
                final_end = min(end, ei_end);
                if (final_start >= final_end)
                        continue;

                __e820_add_region(e820x, final_start, final_end - final_start,
                                  new_type);

                real_updated_size += final_end - final_start;

                /*
                 * left range could be head or tail, so need to update
                 * size at first.
                 */
                ei->size -= final_end - final_start;
                if (ei->addr < final_start)
                        continue;
                ei->addr = final_end;
        }
        return real_updated_size;
}

u64 __init e820_update_range(u64 start, u64 size, unsigned old_type,
                             unsigned new_type)
{
        return __e820_update_range(&e820, start, size, old_type, new_type);
}

static u64 __init e820_update_range_saved(u64 start, u64 size,
                                          unsigned old_type, unsigned new_type)
{
        return __e820_update_range(&e820_saved, start, size, old_type,
                                     new_type);
}

/* make e820 not cover the range */
u64 __init e820_remove_range(u64 start, u64 size, unsigned old_type,
                             int checktype)
{
        int i;
        u64 end;
        u64 real_removed_size = 0;

        if (size > (ULLONG_MAX - start))
                size = ULLONG_MAX - start;

        end = start + size;
        printk(KERN_DEBUG "e820: remove [mem %#010Lx-%#010Lx] ",
               (unsigned long long) start, (unsigned long long) (end - 1));
        if (checktype)
                e820_print_type(old_type);
        printk(KERN_CONT "\n");

        for (i = 0; i < e820.nr_map; i++) {
                struct e820entry *ei = &e820.map[i];
                u64 final_start, final_end;
                u64 ei_end;

                if (checktype && ei->type != old_type)
                        continue;

                ei_end = ei->addr + ei->size;
                /* totally covered? */
                if (ei->addr >= start && ei_end <= end) {
                        real_removed_size += ei->size;
                        memset(ei, 0, sizeof(struct e820entry));
                        continue;
                }

                /* new range is totally covered? */
                if (ei->addr < start && ei_end > end) {
                        e820_add_region(end, ei_end - end, ei->type);
                        ei->size = start - ei->addr;
                        real_removed_size += size;
                        continue;
                }

                /* partially covered */
                final_start = max(start, ei->addr);
                final_end = min(end, ei_end);
                if (final_start >= final_end)
                        continue;
                real_removed_size += final_end - final_start;

                /*
                 * left range could be head or tail, so need to update
                 * size at first.
                 */
                ei->size -= final_end - final_start;
                if (ei->addr < final_start)
                        continue;
                ei->addr = final_end;
        }
        return real_removed_size;
}

void __init update_e820(void)
{
        if (sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map))
                return;
        printk(KERN_INFO "e820: modified physical RAM map:\n");
        e820_print_map("modified");
}
static void __init update_e820_saved(void)
{
        sanitize_e820_map(e820_saved.map, ARRAY_SIZE(e820_saved.map),
                                &e820_saved.nr_map);
}
#define MAX_GAP_END 0x100000000ull
/*
 * Search for a gap in the e820 memory space from start_addr to end_addr.
 */
__init int e820_search_gap(unsigned long *gapstart, unsigned long *gapsize,
                unsigned long start_addr, unsigned long long end_addr)
{
        unsigned long long last;
        int i = e820.nr_map;
        int found = 0;

        last = (end_addr && end_addr < MAX_GAP_END) ? end_addr : MAX_GAP_END;

        while (--i >= 0) {
                unsigned long long start = e820.map[i].addr;
                unsigned long long end = start + e820.map[i].size;

                if (end < start_addr)
                        continue;

                /*
                 * 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;
                                found = 1;
                        }
                }
                if (start < last)
                        last = start;
        }
        return found;
}

/*
 * Search for the biggest gap in the low 32 bits of the e820
 * memory space.  We pass this space to PCI to assign MMIO resources
 * for hotplug or unconfigured devices in.
 * Hopefully the BIOS let enough space left.
 */
__init void e820_setup_gap(void)
{
        unsigned long gapstart, gapsize;
        int found;

        gapstart = 0x10000000;
        gapsize = 0x400000;
        found  = e820_search_gap(&gapstart, &gapsize, 0, MAX_GAP_END);

#ifdef CONFIG_X86_64
        if (!found) {
                gapstart = (max_pfn << PAGE_SHIFT) + 1024*1024;
                printk(KERN_ERR
        "e820: cannot find a gap in the 32bit address range\n"
        "e820: PCI devices with unassigned 32bit BARs may break!\n");
        }
#endif

        /*
         * e820_reserve_resources_late protect stolen RAM already
         */
        pci_mem_start = gapstart;

        printk(KERN_INFO
               "e820: [mem %#010lx-%#010lx] available for PCI devices\n",
               gapstart, gapstart + gapsize - 1);
}

/**
 * Because of the size limitation of struct boot_params, only first
 * 128 E820 memory entries are passed to kernel via
 * boot_params.e820_map, others are passed via SETUP_E820_EXT node of
 * linked list of struct setup_data, which is parsed here.
 */
void __init parse_e820_ext(u64 phys_addr, u32 data_len)
{
        int entries;
        struct e820entry *extmap;
        struct setup_data *sdata;

        sdata = early_memremap(phys_addr, data_len);
        entries = sdata->len / sizeof(struct e820entry);
        extmap = (struct e820entry *)(sdata->data);
        __append_e820_map(extmap, entries);
        sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
        early_iounmap(sdata, data_len);
        printk(KERN_INFO "e820: extended physical RAM map:\n");
        e820_print_map("extended");
}

#if defined(CONFIG_X86_64) || \
        (defined(CONFIG_X86_32) && defined(CONFIG_HIBERNATION))
/**
 * Find the ranges of physical addresses that do not correspond to
 * e820 RAM areas and mark the corresponding pages as nosave for
 * hibernation (32 bit) or software suspend and suspend to RAM (64 bit).
 *
 * This function requires the e820 map to be sorted and without any
 * overlapping entries.
 */
void __init e820_mark_nosave_regions(unsigned long limit_pfn)
{
        int i;
        unsigned long pfn = 0;

        for (i = 0; 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 && ei->type != E820_RESERVED_KERN)
                        register_nosave_region(PFN_UP(ei->addr), pfn);

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

#ifdef CONFIG_ACPI
/**
 * Mark ACPI NVS memory region, so that we can save/restore it during
 * hibernation and the subsequent resume.
 */
static int __init e820_mark_nvs_memory(void)
{
        int i;

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

                if (ei->type == E820_NVS)
                        acpi_nvs_register(ei->addr, ei->size);
        }

        return 0;
}
core_initcall(e820_mark_nvs_memory);
#endif

/*
 * pre allocated 4k and reserved it in memblock and e820_saved
 */
u64 __init early_reserve_e820(u64 size, u64 align)
{
        u64 addr;

        addr = __memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ACCESSIBLE);
        if (addr) {
                e820_update_range_saved(addr, size, E820_RAM, E820_RESERVED);
                printk(KERN_INFO "e820: update e820_saved for early_reserve_e820\n");
                update_e820_saved();
        }

        return addr;
}

#ifdef CONFIG_X86_32
# ifdef CONFIG_X86_PAE
#  define MAX_ARCH_PFN          (1ULL<<(36-PAGE_SHIFT))
# else
#  define MAX_ARCH_PFN          (1ULL<<(32-PAGE_SHIFT))
# endif
#else /* CONFIG_X86_32 */
# define MAX_ARCH_PFN MAXMEM>>PAGE_SHIFT
#endif

/*
 * Find the highest page frame number we have available
 */
static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
{
        int i;
        unsigned long last_pfn = 0;
        unsigned long max_arch_pfn = MAX_ARCH_PFN;

        for (i = 0; i < e820.nr_map; i++) {
                struct e820entry *ei = &e820.map[i];
                unsigned long start_pfn;
                unsigned long end_pfn;

                if (ei->type != type)
                        continue;

                start_pfn = ei->addr >> PAGE_SHIFT;
                end_pfn = (ei->addr + ei->size) >> PAGE_SHIFT;

                if (start_pfn >= limit_pfn)
                        continue;
                if (end_pfn > limit_pfn) {
                        last_pfn = limit_pfn;
                        break;
                }
                if (end_pfn > last_pfn)
                        last_pfn = end_pfn;
        }

        if (last_pfn > max_arch_pfn)
                last_pfn = max_arch_pfn;

        printk(KERN_INFO "e820: last_pfn = %#lx max_arch_pfn = %#lx\n",
                         last_pfn, max_arch_pfn);
        return last_pfn;
}
unsigned long __init e820_end_of_ram_pfn(void)
{
        return e820_end_pfn(MAX_ARCH_PFN, E820_RAM);
}

unsigned long __init e820_end_of_low_ram_pfn(void)
{
        return e820_end_pfn(1UL<<(32 - PAGE_SHIFT), E820_RAM);
}

static void early_panic(char *msg)
{
        early_printk(msg);
        panic(msg);
}

static int userdef __initdata;

/* "mem=nopentium" disables the 4MB page tables. */
static int __init parse_memopt(char *p)
{
        u64 mem_size;

        if (!p)
                return -EINVAL;

        if (!strcmp(p, "nopentium")) {
#ifdef CONFIG_X86_32
                setup_clear_cpu_cap(X86_FEATURE_PSE);
                return 0;
#else
                printk(KERN_WARNING "mem=nopentium ignored! (only supported on x86_32)\n");
                return -EINVAL;
#endif
        }

        userdef = 1;
        mem_size = memparse(p, &p);
        /* don't remove all of memory when handling "mem={invalid}" param */
        if (mem_size == 0)
                return -EINVAL;
        e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);

        return 0;
}
early_param("mem", parse_memopt);

static int __init parse_memmap_one(char *p)
{
        char *oldp;
        u64 start_at, mem_size;

        if (!p)
                return -EINVAL;

        if (!strncmp(p, "exactmap", 8)) {
#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.
                 */
                saved_max_pfn = e820_end_of_ram_pfn();
#endif
                e820.nr_map = 0;
                userdef = 1;
                return 0;
        }

        oldp = p;
        mem_size = memparse(p, &p);
        if (p == oldp)
                return -EINVAL;

        userdef = 1;
        if (*p == '@') {
                start_at = memparse(p+1, &p);
                e820_add_region(start_at, mem_size, E820_RAM);
        } else if (*p == '#') {
                start_at = memparse(p+1, &p);
                e820_add_region(start_at, mem_size, E820_ACPI);
        } else if (*p == '$') {
                start_at = memparse(p+1, &p);
                e820_add_region(start_at, mem_size, E820_RESERVED);
        } else
                e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);

        return *p == '\0' ? 0 : -EINVAL;
}
static int __init parse_memmap_opt(char *str)
{
        while (str) {
                char *k = strchr(str, ',');

                if (k)
                        *k++ = 0;

                parse_memmap_one(str);
                str = k;
        }

        return 0;
}
early_param("memmap", parse_memmap_opt);

void __init finish_e820_parsing(void)
{
        if (userdef) {
                if (sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map),
                                        &e820.nr_map) < 0)
                        early_panic("Invalid user supplied memory map");

                printk(KERN_INFO "e820: user-defined physical RAM map:\n");
                e820_print_map("user");
        }
}

static inline const char *e820_type_to_string(int e820_type)
{
        switch (e820_type) {
        case E820_RESERVED_KERN:
        case E820_RAM:  return "System RAM";
        case E820_ACPI: return "ACPI Tables";
        case E820_NVS:  return "ACPI Non-volatile Storage";
        case E820_UNUSABLE:     return "Unusable memory";
        default:        return "reserved";
        }
}

/*
 * Mark e820 reserved areas as busy for the resource manager.
 */
static struct resource __initdata *e820_res;
void __init e820_reserve_resources(void)
{
        int i;
        struct resource *res;
        u64 end;

        res = alloc_bootmem(sizeof(struct resource) * e820.nr_map);
        e820_res = res;
        for (i = 0; i < e820.nr_map; i++) {
                end = e820.map[i].addr + e820.map[i].size - 1;
                if (end != (resource_size_t)end) {
                        res++;
                        continue;
                }
                res->name = e820_type_to_string(e820.map[i].type);
                res->start = e820.map[i].addr;
                res->end = end;

                res->flags = IORESOURCE_MEM;

                /*
                 * don't register the region that could be conflicted with
                 * pci device BAR resource and insert them later in
                 * pcibios_resource_survey()
                 */
                if (e820.map[i].type != E820_RESERVED || res->start < (1ULL<<20)) {
                        res->flags |= IORESOURCE_BUSY;
                        insert_resource(&iomem_resource, res);
                }
                res++;
        }

        for (i = 0; i < e820_saved.nr_map; i++) {
                struct e820entry *entry = &e820_saved.map[i];
                firmware_map_add_early(entry->addr,
                        entry->addr + entry->size,
                        e820_type_to_string(entry->type));
        }
}

/* How much should we pad RAM ending depending on where it is? */
static unsigned long ram_alignment(resource_size_t pos)
{
        unsigned long mb = pos >> 20;

        /* To 64kB in the first megabyte */
        if (!mb)
                return 64*1024;

        /* To 1MB in the first 16MB */
        if (mb < 16)
                return 1024*1024;

        /* To 64MB for anything above that */
        return 64*1024*1024;
}

#define MAX_RESOURCE_SIZE ((resource_size_t)-1)

void __init e820_reserve_resources_late(void)
{
        int i;
        struct resource *res;

        res = e820_res;
        for (i = 0; i < e820.nr_map; i++) {
                if (!res->parent && res->end)
                        insert_resource_expand_to_fit(&iomem_resource, res);
                res++;
        }

        /*
         * Try to bump up RAM regions to reasonable boundaries to
         * avoid stolen RAM:
         */
        for (i = 0; i < e820.nr_map; i++) {
                struct e820entry *entry = &e820.map[i];
                u64 start, end;

                if (entry->type != E820_RAM)
                        continue;
                start = entry->addr + entry->size;
                end = round_up(start, ram_alignment(start)) - 1;

                if (end > MAX_RESOURCE_SIZE)
                        end = MAX_RESOURCE_SIZE;
                if (start >= end)
                        continue;
                printk(KERN_DEBUG
                       "e820: reserve RAM buffer [mem %#010llx-%#010llx]\n",
                       start, end);
                reserve_region_with_split(&iomem_resource, start, end,
                                          "RAM buffer");
        }
}

char *__init default_machine_specific_memory_setup(void)
{
        char *who = "BIOS-e820";
        u32 new_nr;
        /*
         * Try to copy the BIOS-supplied E820-map.
         *
         * Otherwise fake a memory map; one section from 0k->640k,
         * the next section from 1mb->appropriate_mem_k
         */
        new_nr = boot_params.e820_entries;
        sanitize_e820_map(boot_params.e820_map,
                        ARRAY_SIZE(boot_params.e820_map),
                        &new_nr);
        boot_params.e820_entries = new_nr;
        if (append_e820_map(boot_params.e820_map, boot_params.e820_entries)
          < 0) {
                u64 mem_size;

                /* compare results from other methods and take the greater */
                if (boot_params.alt_mem_k
                    < boot_params.screen_info.ext_mem_k) {
                        mem_size = boot_params.screen_info.ext_mem_k;
                        who = "BIOS-88";
                } else {
                        mem_size = boot_params.alt_mem_k;
                        who = "BIOS-e801";
                }

                e820.nr_map = 0;
                e820_add_region(0, LOWMEMSIZE(), E820_RAM);
                e820_add_region(HIGH_MEMORY, mem_size << 10, E820_RAM);
        }

        /* In case someone cares... */
        return who;
}

void __init setup_memory_map(void)
{
        char *who;

        who = x86_init.resources.memory_setup();
        memcpy(&e820_saved, &e820, sizeof(struct e820map));
        printk(KERN_INFO "e820: BIOS-provided physical RAM map:\n");
        e820_print_map(who);
}

void __init memblock_x86_fill(void)
{
        int i;
        u64 end;

        /*
         * EFI may have more than 128 entries
         * We are safe to enable resizing, beause memblock_x86_fill()
         * is rather later for x86
         */
        memblock_allow_resize();

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

                end = ei->addr + ei->size;
                if (end != (resource_size_t)end)
                        continue;

                if (ei->type != E820_RAM && ei->type != E820_RESERVED_KERN)
                        continue;

                memblock_add(ei->addr, ei->size);
        }

        /* throw away partial pages */
        memblock_trim_memory(PAGE_SIZE);

        memblock_dump_all();
}

void __init memblock_find_dma_reserve(void)
{
#ifdef CONFIG_X86_64
        u64 nr_pages = 0, nr_free_pages = 0;
        unsigned long start_pfn, end_pfn;
        phys_addr_t start, end;
        int i;
        u64 u;

        /*
         * need to find out used area below MAX_DMA_PFN
         * need to use memblock to get free size in [0, MAX_DMA_PFN]
         * at first, and assume boot_mem will not take below MAX_DMA_PFN
         */
        for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
                start_pfn = min(start_pfn, MAX_DMA_PFN);
                end_pfn = min(end_pfn, MAX_DMA_PFN);
                nr_pages += end_pfn - start_pfn;
        }

        for_each_free_mem_range(u, NUMA_NO_NODE, &start, &end, NULL) {
                start_pfn = min_t(unsigned long, PFN_UP(start), MAX_DMA_PFN);
                end_pfn = min_t(unsigned long, PFN_DOWN(end), MAX_DMA_PFN);
                if (start_pfn < end_pfn)
                        nr_free_pages += end_pfn - start_pfn;
        }

        set_dma_reserve(nr_pages - nr_free_pages);
#endif
}