1. 根目录:
2. arch
3. frv
4. mm
5. highmem.c

/* highmem.c: arch-specific highmem stuff
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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);

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

	preempt_disable();
	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();
	preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);