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/*

 *  linux/mm/bootmem.c

 *

 *  Copyright (C) 1999 Ingo Molnar

 *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999

 *

 *  simple boot-time physical memory area allocator and

 *  free memory collector. It's used to deal with reserved

 *  system memory and memory holes as well.

 */

#include <linux/mm.h>

#include <linux/kernel_stat.h>

#include <linux/swap.h>

#include <linux/swapctl.h>

#include <linux/interrupt.h>

#include <linux/init.h>

#include <linux/bootmem.h>

#include <linux/mmzone.h>

#include <asm/dma.h>

#include <asm/io.h>

/*

 * Access to this subsystem has to be serialized externally. (this is

 * true for the boot process anyway)

 */

unsigned long max_low_pfn;

unsigned long min_low_pfn;

unsigned long max_pfn;

/* return the number of _pages_ that will be allocated for the boot bitmap */

unsigned long __init bootmem_bootmap_pages (unsigned long pages)

{

        unsigned long mapsize;

        mapsize = (pages+7)/8;

        mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;

        mapsize >>= PAGE_SHIFT;

        return mapsize;

}

/*

 * Called once to set up the allocator itself.

 */

static unsigned long __init init_bootmem_core (pg_data_t *pgdat,

        unsigned long mapstart, unsigned long start, unsigned long end)

{

        bootmem_data_t *bdata = pgdat->bdata;

        unsigned long mapsize = ((end - start)+7)/8;

        pgdat->node_next = pgdat_list;

        pgdat_list = pgdat;

        mapsize = (mapsize + (sizeof(long) - 1UL)) & ~(sizeof(long) - 1UL);

        bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);

        bdata->node_boot_start = (start << PAGE_SHIFT);

        bdata->node_low_pfn = end;

        /*

         * Initially all pages are reserved - setup_arch() has to

         * register free RAM areas explicitly.

         */

        memset(bdata->node_bootmem_map, 0xff, mapsize);

        return mapsize;

}

/*

 * Marks a particular physical memory range as unallocatable. Usable RAM

 * might be used for boot-time allocations - or it might get added

 * to the free page pool later on.

 */

static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)

{

        unsigned long i;

        /*

         * round up, partially reserved pages are considered

         * fully reserved.

         */

        unsigned long sidx = (addr - bdata->node_boot_start)/PAGE_SIZE;

        unsigned long eidx = (addr + size - bdata->node_boot_start +

                                                        PAGE_SIZE-1)/PAGE_SIZE;

        unsigned long end = (addr + size + PAGE_SIZE-1)/PAGE_SIZE;

        if (!size) BUG();

        if (sidx < 0)

                BUG();

        if (eidx < 0)

                BUG();

        if (sidx >= eidx)

                BUG();

        if ((addr >> PAGE_SHIFT) >= bdata->node_low_pfn)

                BUG();

        if (end > bdata->node_low_pfn)

                BUG();

        for (i = sidx; i < eidx; i++)

                if (test_and_set_bit(i, bdata->node_bootmem_map))

                        printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);

}

static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)

{

        unsigned long i;

        unsigned long start;

        /*

         * round down end of usable mem, partially free pages are

         * considered reserved.

         */

        unsigned long sidx;

        unsigned long eidx = (addr + size - bdata->node_boot_start)/PAGE_SIZE;

        unsigned long end = (addr + size)/PAGE_SIZE;

        if (!size) BUG();

        if (end > bdata->node_low_pfn)

                BUG();

        /*

         * Round up the beginning of the address.

         */

        start = (addr + PAGE_SIZE-1) / PAGE_SIZE;

        sidx = start - (bdata->node_boot_start/PAGE_SIZE);

        for (i = sidx; i < eidx; i++) {

                if (!test_and_clear_bit(i, bdata->node_bootmem_map))

                        BUG();

        }

}

/*

 * We 'merge' subsequent allocations to save space. We might 'lose'

 * some fraction of a page if allocations cannot be satisfied due to

 * size constraints on boxes where there is physical RAM space

 * fragmentation - in these cases * (mostly large memory boxes) this

 * is not a problem.

 *

 * On low memory boxes we get it right in 100% of the cases.

 */

/*

 * alignment has to be a power of 2 value.

 */

static void * __init __alloc_bootmem_core (bootmem_data_t *bdata,

        unsigned long size, unsigned long align, unsigned long goal)

{

        unsigned long i, start = 0;

        void *ret;

        unsigned long offset, remaining_size;

        unsigned long areasize, preferred, incr;

        unsigned long eidx = bdata->node_low_pfn - (bdata->node_boot_start >>

                                                        PAGE_SHIFT);

        if (!size) BUG();

        if (align & (align-1))

                BUG();

        offset = 0;

        if (align &&

            (bdata->node_boot_start & (align - 1UL)) != 0)

                offset = (align - (bdata->node_boot_start & (align - 1UL)));

        offset >>= PAGE_SHIFT;

        /*

         * We try to allocate bootmem pages above 'goal'

         * first, then we try to allocate lower pages.

         */

        if (goal && (goal >= bdata->node_boot_start) &&

                        ((goal >> PAGE_SHIFT) < bdata->node_low_pfn)) {

                preferred = goal - bdata->node_boot_start;

        } else

                preferred = 0;

        preferred = ((preferred + align - 1) & ~(align - 1)) >> PAGE_SHIFT;

        preferred += offset;

        areasize = (size+PAGE_SIZE-1)/PAGE_SIZE;

        incr = align >> PAGE_SHIFT ? : 1;

restart_scan:

        for (i = preferred; i < eidx; i += incr) {

                unsigned long j;

                if (test_bit(i, bdata->node_bootmem_map))

                        continue;

                for (j = i + 1; j < i + areasize; ++j) {

                        if (j >= eidx)

                                goto fail_block;

                        if (test_bit (j, bdata->node_bootmem_map))

                                goto fail_block;

                }

                start = i;

                goto found;

        fail_block:;

        }

        if (preferred) {

                preferred = offset;

                goto restart_scan;

        }

        return NULL;

found:

        if (start >= eidx)

                BUG();

        /*

         * Is the next page of the previous allocation-end the start

         * of this allocation's buffer? If yes then we can 'merge'

         * the previous partial page with this allocation.

         */

        if (align <= PAGE_SIZE

            && bdata->last_offset && bdata->last_pos+1 == start) {

                offset = (bdata->last_offset+align-1) & ~(align-1);

                if (offset > PAGE_SIZE)

                        BUG();

                remaining_size = PAGE_SIZE-offset;

                if (size < remaining_size) {

                        areasize = 0;

                        // last_pos unchanged

                        bdata->last_offset = offset+size;

                        ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +

                                                bdata->node_boot_start);

                } else {

                        remaining_size = size - remaining_size;

                        areasize = (remaining_size+PAGE_SIZE-1)/PAGE_SIZE;

                        ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +

                                                bdata->node_boot_start);

                        bdata->last_pos = start+areasize-1;

                        bdata->last_offset = remaining_size;

                }

                bdata->last_offset &= ~PAGE_MASK;

        } else {

                bdata->last_pos = start + areasize - 1;

                bdata->last_offset = size & ~PAGE_MASK;

                ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);

        }

        /*

         * Reserve the area now:

         */

        for (i = start; i < start+areasize; i++)

                if (test_and_set_bit(i, bdata->node_bootmem_map))

                        BUG();

        memset(ret, 0, size);

        return ret;

}

static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)

{

        struct page *page = pgdat->node_mem_map;

        bootmem_data_t *bdata = pgdat->bdata;

        unsigned long i, count, total = 0;

        unsigned long idx;

        if (!bdata->node_bootmem_map) BUG();

        count = 0;

        idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);

        for (i = 0; i < idx; i++, page++) {

                if (!test_bit(i, bdata->node_bootmem_map)) {

                        count++;

                        ClearPageReserved(page);

                        set_page_count(page, 1);

                        __free_page(page);

                }

        }

        total += count;

        /*

         * Now free the allocator bitmap itself, it's not

         * needed anymore:

         */

        page = virt_to_page(bdata->node_bootmem_map);

        count = 0;

        for (i = 0; i < ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE-1)/PAGE_SIZE; i++,page++) {

                count++;

                ClearPageReserved(page);

                set_page_count(page, 1);

                __free_page(page);

        }

        total += count;

        bdata->node_bootmem_map = NULL;

        return total;

}

unsigned long __init init_bootmem_node (pg_data_t *pgdat, unsigned long freepfn, unsigned long startpfn, unsigned long endpfn)

{

        return(init_bootmem_core(pgdat, freepfn, startpfn, endpfn));

}

void __init reserve_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)

{

        reserve_bootmem_core(pgdat->bdata, physaddr, size);

}

void __init free_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)

{

        return(free_bootmem_core(pgdat->bdata, physaddr, size));

}

unsigned long __init free_all_bootmem_node (pg_data_t *pgdat)

{

        return(free_all_bootmem_core(pgdat));

}

unsigned long __init init_bootmem (unsigned long start, unsigned long pages)

{

        max_low_pfn = pages;

        min_low_pfn = start;

        return(init_bootmem_core(&contig_page_data, start, 0, pages));

}

void __init reserve_bootmem (unsigned long addr, unsigned long size)

{

        reserve_bootmem_core(contig_page_data.bdata, addr, size);

}

void __init free_bootmem (unsigned long addr, unsigned long size)

{

        return(free_bootmem_core(contig_page_data.bdata, addr, size));

}

unsigned long __init free_all_bootmem (void)

{

        return(free_all_bootmem_core(&contig_page_data));

}

void * __init __alloc_bootmem (unsigned long size, unsigned long align, unsigned long goal)

{

        pg_data_t *pgdat;

        void *ptr;

        for_each_pgdat(pgdat)

                if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,

                                                align, goal)))

                        return(ptr);

        /*

         * Whoops, we cannot satisfy the allocation request.

         */

        printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);

        panic("Out of memory");

        return NULL;

}

void * __init __alloc_bootmem_node (pg_data_t *pgdat, unsigned long size, unsigned long align, unsigned long goal)

{

        void *ptr;

        ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal);

        if (ptr)

                return (ptr);

        /*

         * Whoops, we cannot satisfy the allocation request.

         */

        printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);

        panic("Out of memory");

        return NULL;

}