linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * High memory handling common code and variables.

 *

 * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de

 *          Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de

 *

 *

 * Redesigned the x86 32-bit VM architecture to deal with

 * 64-bit physical space. With current x86 CPUs this

 * means up to 64 Gigabytes physical RAM.

 *

 * Rewrote high memory support to move the page cache into

 * high memory. Implemented permanent (schedulable) kmaps

 * based on Linus' idea.

 *

 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>

 */

​

#include <linux/mm.h>

#include <linux/export.h>

#include <linux/swap.h>

#include <linux/bio.h>

#include <linux/pagemap.h>

#include <linux/mempool.h>

#include <linux/blkdev.h>

#include <linux/init.h>

#include <linux/hash.h>

#include <linux/highmem.h>

#include <linux/kgdb.h>

#include <asm/tlbflush.h>

​

​

#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)

DEFINE_PER_CPU(int, __kmap_atomic_idx);

#endif

​

/*

 * Virtual_count is not a pure "count".

 *  0 means that it is not mapped, and has not been mapped

 *    since a TLB flush - it is usable.

 *  1 means that there are no users, but it has been mapped

 *    since the last TLB flush - so we can't use it.

 *  n means that there are (n-1) current users of it.

 */

#ifdef CONFIG_HIGHMEM

​

/*

 * Architecture with aliasing data cache may define the following family of

 * helper functions in its asm/highmem.h to control cache color of virtual

 * addresses where physical memory pages are mapped by kmap.

 */

#ifndef get_pkmap_color

​

/*

 * Determine color of virtual address where the page should be mapped.

 */

static inline unsigned int get_pkmap_color(struct page *page)

{

    return 0;

}

#define get_pkmap_color get_pkmap_color

​

/*

 * Get next index for mapping inside PKMAP region for page with given color.

 */

static inline unsigned int get_next_pkmap_nr(unsigned int color)

{

    static unsigned int last_pkmap_nr;

​

    last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;

    return last_pkmap_nr;

}

​

/*

 * Determine if page index inside PKMAP region (pkmap_nr) of given color

 * has wrapped around PKMAP region end. When this happens an attempt to

 * flush all unused PKMAP slots is made.

 */

static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)

{

    return pkmap_nr == 0;

}

​

/*

 * Get the number of PKMAP entries of the given color. If no free slot is

 * found after checking that many entries, kmap will sleep waiting for

 * someone to call kunmap and free PKMAP slot.

 */

static inline int get_pkmap_entries_count(unsigned int color)

{

    return LAST_PKMAP;