highmem.c

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/* highmem.c: arch-specific highmem stuff
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <linux/highmem.h>
#include <linux/module.h>

void *kmap(struct page *page)
{
    might_sleep();
    if (!PageHighMem(page))
        return page_address(page);
    return kmap_high(page);
}

EXPORT_SYMBOL(kmap);

void kunmap(struct page *page)
{
    if (in_interrupt())
        BUG();
    if (!PageHighMem(page))
        return;
    kunmap_high(page);
}

EXPORT_SYMBOL(kunmap);

struct page *kmap_atomic_to_page(void *ptr)
{
    return virt_to_page(ptr);
}

void *kmap_atomic(struct page *page)
{
    unsigned long paddr;
    int type;

    pagefault_disable();
    type = kmap_atomic_idx_push();
    paddr = page_to_phys(page);

    switch (type) {
    /*
     * The first 4 primary maps are reserved for architecture code
     */
    case 0:     return __kmap_atomic_primary(0, paddr, 6);
    case 1:     return __kmap_atomic_primary(0, paddr, 7);
    case 2:     return __kmap_atomic_primary(0, paddr, 8);
    case 3:     return __kmap_atomic_primary(0, paddr, 9);
    case 4:     return __kmap_atomic_primary(0, paddr, 10);

    case 5 ... 5 + NR_TLB_LINES - 1:
        return __kmap_atomic_secondary(type - 5, paddr);

    default:
        BUG();
        return NULL;
    }
}
EXPORT_SYMBOL(kmap_atomic);

void __kunmap_atomic(void *kvaddr)
{
    int type = kmap_atomic_idx();
    switch (type) {
    case 0:     __kunmap_atomic_primary(0, 6);  break;
    case 1:     __kunmap_atomic_primary(0, 7);  break;
    case 2:     __kunmap_atomic_primary(0, 8);  break;
    case 3:     __kunmap_atomic_primary(0, 9);  break;
    case 4:     __kunmap_atomic_primary(0, 10); break;

    case 5 ... 5 + NR_TLB_LINES - 1:
        __kunmap_atomic_secondary(type - 5, kvaddr);
        break;

    default:
        BUG();
    }
    kmap_atomic_idx_pop();
    pagefault_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);