Merge branch 'linus' into x86/mm

[mirror_ubuntu-hirsute-kernel.git] / arch / x86 / kernel / e820.c

/*
 * 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/bootmem.h>
#include <linux/ioport.h>
#include <linux/string.h>
#include <linux/kexec.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/pfn.h>
#include <linux/suspend.h>
#include <linux/firmware-map.h>

#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/e820.h>
#include <asm/proto.h>
#include <asm/setup.h>
#include <asm/trampoline.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 "Ooops! Too many entries in the memory map!\n");
                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: %016Lx - %016Lx ", who,
                       (unsigned long long) e820.map[i].addr,
                       (unsigned long long)
                       (e820.map[i].addr + e820.map[i].size));
                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) and will
 * be updated on return, 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_
 */

int __init sanitize_e820_map(struct e820entry *biosmap, int max_nr_map,
                             u32 *pnr_map)
{
        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*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;
        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;

        /* 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) */
        still_changing = 1;
        while (still_changing)  {
                still_changing = 0;
                for (i = 1; i < chg_nr; i++)  {
                        unsigned long long curaddr, lastaddr;
                        unsigned long long curpbaddr, lastpbaddr;

                        curaddr = change_point[i]->addr;
                        lastaddr = change_point[i - 1]->addr;
                        curpbaddr = change_point[i]->pbios->addr;
                        lastpbaddr = change_point[i - 1]->pbios->addr;

                        /*
                         * swap entries, when:
                         *
                         * curaddr > lastaddr or
                         * curaddr == lastaddr and curaddr == curpbaddr and
                         * lastaddr != lastpbaddr
                         */
                        if (curaddr < lastaddr ||
                            (curaddr == lastaddr && curaddr == curpbaddr &&
                             lastaddr != lastpbaddr)) {
                                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)
                                        /*
                                         * 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 range: %016Lx - %016Lx ",
                       (unsigned long long) start,
                       (unsigned long long) end);
        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 range: %016Lx - %016Lx ",
                       (unsigned long long) start,
                       (unsigned long long) end);
        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;

                if (checktype && ei->type != old_type)
                        continue;
                /* totally covered? */
                if (ei->addr >= start &&
                    (ei->addr + ei->size) <= (start + size)) {
                        real_removed_size += ei->size;
                        memset(ei, 0, sizeof(struct e820entry));
                        continue;
                }
                /* partially covered */
                final_start = max(start, ei->addr);
                final_end = min(start + size, ei->addr + ei->size);
                if (final_start >= final_end)
                        continue;
                real_removed_size += final_end - final_start;

                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)
{
        u32 nr_map;

        nr_map = e820.nr_map;
        if (sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &nr_map))
                return;
        e820.nr_map = nr_map;
        printk(KERN_INFO "modified physical RAM map:\n");
        e820_print_map("modified");
}
static void __init update_e820_saved(void)
{
        u32 nr_map;

        nr_map = e820_saved.nr_map;
        if (sanitize_e820_map(e820_saved.map, ARRAY_SIZE(e820_saved.map), &nr_map))
                return;
        e820_saved.nr_map = 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
        "PCI: Warning: Cannot find a gap in the 32bit address range\n"
        "PCI: Unassigned devices with 32bit resource registers may break!\n");
        }
#endif

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

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

/**
 * 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(struct setup_data *sdata, unsigned long pa_data)
{
        u32 map_len;
        int entries;
        struct e820entry *extmap;

        entries = sdata->len / sizeof(struct e820entry);
        map_len = sdata->len + sizeof(struct setup_data);
        if (map_len > PAGE_SIZE)
                sdata = early_ioremap(pa_data, map_len);
        extmap = (struct e820entry *)(sdata->data);
        __append_e820_map(extmap, entries);
        sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
        if (map_len > PAGE_SIZE)
                early_iounmap(sdata, map_len);
        printk(KERN_INFO "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 and assumes the first e820 area to be RAM.
 */
void __init e820_mark_nosave_regions(unsigned long limit_pfn)
{
        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 && ei->type != E820_RESERVED_KERN)
                        register_nosave_region(PFN_UP(ei->addr), pfn);

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

#ifdef CONFIG_HIBERNATION
/**
 * 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)
                        hibernate_nvs_register(ei->addr, ei->size);
        }

        return 0;
}
core_initcall(e820_mark_nvs_memory);
#endif

/*
 * Early reserved memory areas.
 */
#define MAX_EARLY_RES 32

struct early_res {
        u64 start, end;
        char name[16];
        char overlap_ok;
};
static struct early_res early_res[MAX_EARLY_RES] __initdata = {
        { 0, PAGE_SIZE, "BIOS data page", 1 },  /* BIOS data page */
#if defined(CONFIG_X86_32) && defined(CONFIG_X86_TRAMPOLINE)
        /*
         * But first pinch a few for the stack/trampoline stuff
         * FIXME: Don't need the extra page at 4K, but need to fix
         * trampoline before removing it. (see the GDT stuff)
         */
        { PAGE_SIZE, PAGE_SIZE + PAGE_SIZE, "EX TRAMPOLINE", 1 },
#endif

        {}
};

static int __init find_overlapped_early(u64 start, u64 end)
{
        int i;
        struct early_res *r;

        for (i = 0; i < MAX_EARLY_RES && early_res[i].end; i++) {
                r = &early_res[i];
                if (end > r->start && start < r->end)
                        break;
        }

        return i;
}

/*
 * Drop the i-th range from the early reservation map,
 * by copying any higher ranges down one over it, and
 * clearing what had been the last slot.
 */
static void __init drop_range(int i)
{
        int j;

        for (j = i + 1; j < MAX_EARLY_RES && early_res[j].end; j++)
                ;

        memmove(&early_res[i], &early_res[i + 1],
               (j - 1 - i) * sizeof(struct early_res));

        early_res[j - 1].end = 0;
}

/*
 * Split any existing ranges that:
 *  1) are marked 'overlap_ok', and
 *  2) overlap with the stated range [start, end)
 * into whatever portion (if any) of the existing range is entirely
 * below or entirely above the stated range.  Drop the portion
 * of the existing range that overlaps with the stated range,
 * which will allow the caller of this routine to then add that
 * stated range without conflicting with any existing range.
 */
static void __init drop_overlaps_that_are_ok(u64 start, u64 end)
{
        int i;
        struct early_res *r;
        u64 lower_start, lower_end;
        u64 upper_start, upper_end;
        char name[16];

        for (i = 0; i < MAX_EARLY_RES && early_res[i].end; i++) {
                r = &early_res[i];

                /* Continue past non-overlapping ranges */
                if (end <= r->start || start >= r->end)
                        continue;

                /*
                 * Leave non-ok overlaps as is; let caller
                 * panic "Overlapping early reservations"
                 * when it hits this overlap.
                 */
                if (!r->overlap_ok)
                        return;

                /*
                 * We have an ok overlap.  We will drop it from the early
                 * reservation map, and add back in any non-overlapping
                 * portions (lower or upper) as separate, overlap_ok,
                 * non-overlapping ranges.
                 */

                /* 1. Note any non-overlapping (lower or upper) ranges. */
                strncpy(name, r->name, sizeof(name) - 1);

                lower_start = lower_end = 0;
                upper_start = upper_end = 0;
                if (r->start < start) {
                        lower_start = r->start;
                        lower_end = start;
                }
                if (r->end > end) {
                        upper_start = end;
                        upper_end = r->end;
                }

                /* 2. Drop the original ok overlapping range */
                drop_range(i);

                i--;            /* resume for-loop on copied down entry */

                /* 3. Add back in any non-overlapping ranges. */
                if (lower_end)
                        reserve_early_overlap_ok(lower_start, lower_end, name);
                if (upper_end)
                        reserve_early_overlap_ok(upper_start, upper_end, name);
        }
}

static void __init __reserve_early(u64 start, u64 end, char *name,
                                                int overlap_ok)
{
        int i;
        struct early_res *r;

        i = find_overlapped_early(start, end);
        if (i >= MAX_EARLY_RES)
                panic("Too many early reservations");
        r = &early_res[i];
        if (r->end)
                panic("Overlapping early reservations "
                      "%llx-%llx %s to %llx-%llx %s\n",
                      start, end - 1, name?name:"", r->start,
                      r->end - 1, r->name);
        r->start = start;
        r->end = end;
        r->overlap_ok = overlap_ok;
        if (name)
                strncpy(r->name, name, sizeof(r->name) - 1);
}

/*
 * A few early reservtations come here.
 *
 * The 'overlap_ok' in the name of this routine does -not- mean it
 * is ok for these reservations to overlap an earlier reservation.
 * Rather it means that it is ok for subsequent reservations to
 * overlap this one.
 *
 * Use this entry point to reserve early ranges when you are doing
 * so out of "Paranoia", reserving perhaps more memory than you need,
 * just in case, and don't mind a subsequent overlapping reservation
 * that is known to be needed.
 *
 * The drop_overlaps_that_are_ok() call here isn't really needed.
 * It would be needed if we had two colliding 'overlap_ok'
 * reservations, so that the second such would not panic on the
 * overlap with the first.  We don't have any such as of this
 * writing, but might as well tolerate such if it happens in
 * the future.
 */
void __init reserve_early_overlap_ok(u64 start, u64 end, char *name)
{
        drop_overlaps_that_are_ok(start, end);
        __reserve_early(start, end, name, 1);
}

/*
 * Most early reservations come here.
 *
 * We first have drop_overlaps_that_are_ok() drop any pre-existing
 * 'overlap_ok' ranges, so that we can then reserve this memory
 * range without risk of panic'ing on an overlapping overlap_ok
 * early reservation.
 */
void __init reserve_early(u64 start, u64 end, char *name)
{
        if (start >= end)
                return;

        drop_overlaps_that_are_ok(start, end);
        __reserve_early(start, end, name, 0);
}

void __init free_early(u64 start, u64 end)
{
        struct early_res *r;
        int i;

        i = find_overlapped_early(start, end);
        r = &early_res[i];
        if (i >= MAX_EARLY_RES || r->end != end || r->start != start)
                panic("free_early on not reserved area: %llx-%llx!",
                         start, end - 1);

        drop_range(i);
}

void __init early_res_to_bootmem(u64 start, u64 end)
{
        int i, count;
        u64 final_start, final_end;

        count  = 0;
        for (i = 0; i < MAX_EARLY_RES && early_res[i].end; i++)
                count++;

        printk(KERN_INFO "(%d early reservations) ==> bootmem [%010llx - %010llx]\n",
                         count, start, end);
        for (i = 0; i < count; i++) {
                struct early_res *r = &early_res[i];
                printk(KERN_INFO "  #%d [%010llx - %010llx] %16s", i,
                        r->start, r->end, r->name);
                final_start = max(start, r->start);
                final_end = min(end, r->end);
                if (final_start >= final_end) {
                        printk(KERN_CONT "\n");
                        continue;
                }
                printk(KERN_CONT " ==> [%010llx - %010llx]\n",
                        final_start, final_end);
                reserve_bootmem_generic(final_start, final_end - final_start,
                                BOOTMEM_DEFAULT);
        }
}

/* Check for already reserved areas */
static inline int __init bad_addr(u64 *addrp, u64 size, u64 align)
{
        int i;
        u64 addr = *addrp;
        int changed = 0;
        struct early_res *r;
again:
        i = find_overlapped_early(addr, addr + size);
        r = &early_res[i];
        if (i < MAX_EARLY_RES && r->end) {
                *addrp = addr = round_up(r->end, align);
                changed = 1;
                goto again;
        }
        return changed;
}

/* Check for already reserved areas */
static inline int __init bad_addr_size(u64 *addrp, u64 *sizep, u64 align)
{
        int i;
        u64 addr = *addrp, last;
        u64 size = *sizep;
        int changed = 0;
again:
        last = addr + size;
        for (i = 0; i < MAX_EARLY_RES && early_res[i].end; i++) {
                struct early_res *r = &early_res[i];
                if (last > r->start && addr < r->start) {
                        size = r->start - addr;
                        changed = 1;
                        goto again;
                }
                if (last > r->end && addr < r->end) {
                        addr = round_up(r->end, align);
                        size = last - addr;
                        changed = 1;
                        goto again;
                }
                if (last <= r->end && addr >= r->start) {
                        (*sizep)++;
                        return 0;
                }
        }
        if (changed) {
                *addrp = addr;
                *sizep = size;
        }
        return changed;
}

/*
 * Find a free area with specified alignment in a specific range.
 */
u64 __init find_e820_area(u64 start, u64 end, u64 size, u64 align)
{
        int i;

        for (i = 0; i < e820.nr_map; i++) {
                struct e820entry *ei = &e820.map[i];
                u64 addr, last;
                u64 ei_last;

                if (ei->type != E820_RAM)
                        continue;
                addr = round_up(ei->addr, align);
                ei_last = ei->addr + ei->size;
                if (addr < start)
                        addr = round_up(start, align);
                if (addr >= ei_last)
                        continue;
                while (bad_addr(&addr, size, align) && addr+size <= ei_last)
                        ;
                last = addr + size;
                if (last > ei_last)
                        continue;
                if (last > end)
                        continue;
                return addr;
        }
        return -1ULL;
}

/*
 * Find next free range after *start
 */
u64 __init find_e820_area_size(u64 start, u64 *sizep, u64 align)
{
        int i;

        for (i = 0; i < e820.nr_map; i++) {
                struct e820entry *ei = &e820.map[i];
                u64 addr, last;
                u64 ei_last;

                if (ei->type != E820_RAM)
                        continue;
                addr = round_up(ei->addr, align);
                ei_last = ei->addr + ei->size;
                if (addr < start)
                        addr = round_up(start, align);
                if (addr >= ei_last)
                        continue;
                *sizep = ei_last - addr;
                while (bad_addr_size(&addr, sizep, align) &&
                        addr + *sizep <= ei_last)
                        ;
                last = addr + *sizep;
                if (last > ei_last)
                        continue;
                return addr;
        }

        return -1ULL;
}

/*
 * pre allocated 4k and reserved it in e820
 */
u64 __init early_reserve_e820(u64 startt, u64 sizet, u64 align)
{
        u64 size = 0;
        u64 addr;
        u64 start;

        for (start = startt; ; start += size) {
                start = find_e820_area_size(start, &size, align);
                if (!(start + 1))
                        return 0;
                if (size >= sizet)
                        break;
        }

#ifdef CONFIG_X86_32
        if (start >= MAXMEM)
                return 0;
        if (start + size > MAXMEM)
                size = MAXMEM - start;
#endif

        addr = round_down(start + size - sizet, align);
        if (addr < start)
                return 0;
        e820_update_range(addr, sizet, E820_RAM, E820_RESERVED);
        e820_update_range_saved(addr, sizet, E820_RAM, E820_RESERVED);
        printk(KERN_INFO "update e820 for early_reserve_e820\n");
        update_e820();
        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 "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);
}
/*
 * Finds an active region in the address range from start_pfn to last_pfn and
 * returns its range in ei_startpfn and ei_endpfn for the e820 entry.
 */
int __init e820_find_active_region(const struct e820entry *ei,
                                  unsigned long start_pfn,
                                  unsigned long last_pfn,
                                  unsigned long *ei_startpfn,
                                  unsigned long *ei_endpfn)
{
        u64 align = PAGE_SIZE;

        *ei_startpfn = round_up(ei->addr, align) >> PAGE_SHIFT;
        *ei_endpfn = round_down(ei->addr + ei->size, align) >> PAGE_SHIFT;

        /* Skip map entries smaller than a page */
        if (*ei_startpfn >= *ei_endpfn)
                return 0;

        /* Skip if map is outside the node */
        if (ei->type != E820_RAM || *ei_endpfn <= start_pfn ||
                                    *ei_startpfn >= last_pfn)
                return 0;

        /* Check for overlaps */
        if (*ei_startpfn < start_pfn)
                *ei_startpfn = start_pfn;
        if (*ei_endpfn > last_pfn)
                *ei_endpfn = last_pfn;

        return 1;
}

/* Walk the e820 map and register active regions within a node */
void __init e820_register_active_regions(int nid, unsigned long start_pfn,
                                         unsigned long last_pfn)
{
        unsigned long ei_startpfn;
        unsigned long ei_endpfn;
        int i;

        for (i = 0; i < e820.nr_map; i++)
                if (e820_find_active_region(&e820.map[i],
                                            start_pfn, last_pfn,
                                            &ei_startpfn, &ei_endpfn))
                        add_active_range(nid, ei_startpfn, ei_endpfn);
}

/*
 * Find the hole size (in bytes) in the memory range.
 * @start: starting address of the memory range to scan
 * @end: ending address of the memory range to scan
 */
u64 __init e820_hole_size(u64 start, u64 end)
{
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long last_pfn = end >> PAGE_SHIFT;
        unsigned long ei_startpfn, ei_endpfn, ram = 0;
        int i;

        for (i = 0; i < e820.nr_map; i++) {
                if (e820_find_active_region(&e820.map[i],
                                            start_pfn, last_pfn,
                                            &ei_startpfn, &ei_endpfn))
                        ram += ei_endpfn - ei_startpfn;
        }
        return end - start - ((u64)ram << PAGE_SHIFT);
}

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;

#ifdef CONFIG_X86_32
        if (!strcmp(p, "nopentium")) {
                setup_clear_cpu_cap(X86_FEATURE_PSE);
                return 0;
        }
#endif

        userdef = 1;
        mem_size = memparse(p, &p);
        e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);

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

static int __init parse_memmap_opt(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;
}
early_param("memmap", parse_memmap_opt);

void __init finish_e820_parsing(void)
{
        if (userdef) {
                u32 nr = e820.nr_map;

                if (sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &nr) < 0)
                        early_panic("Invalid user supplied memory map");
                e820.nr_map = nr;

                printk(KERN_INFO "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 - 1,
                        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;
                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 "BIOS-provided physical RAM map:\n");
        e820_print_map(who);
}