1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * highmem.h: virtual kernel memory mappings for high memory
4 *
5 * Used in CONFIG_HIGHMEM systems for memory pages which
6 * are not addressable by direct kernel virtual addresses.
7 *
8 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
9 *		      Gerhard.Wichert@pdb.siemens.de
10 *
11 *
12 * Redesigned the x86 32-bit VM architecture to deal with
13 * up to 16 Terabyte physical memory. With current x86 CPUs
14 * we now support up to 64 Gigabytes physical RAM.
15 *
16 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
17 */
18#ifndef _ASM_HIGHMEM_H
19#define _ASM_HIGHMEM_H
20
21#ifdef __KERNEL__
22
23#include <linux/init.h>
24#include <linux/interrupt.h>
25#include <linux/uaccess.h>
26#include <asm/fixmap.h>
27
28extern pte_t *kmap_pte;
29extern pte_t *pkmap_page_table;
30
31/*
32 * Right now we initialize only a single pte table. It can be extended
33 * easily, subsequent pte tables have to be allocated in one physical
34 * chunk of RAM.
35 */
36/*
37 * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
38 * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
39 * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
40 * in case of 16K/64K/256K page sizes.
41 */
42
43#define PKMAP_ORDER	PTE_SHIFT
44#define LAST_PKMAP	(1 << PKMAP_ORDER)
45
46#define PKMAP_BASE	((FIXADDR_START - PAGE_SIZE * (LAST_PKMAP + 1)) \
47								& PMD_MASK)
48
49#define LAST_PKMAP_MASK	(LAST_PKMAP - 1)
50#define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
51#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
52
53#define flush_cache_kmaps()	{ flush_icache(); flush_dcache(); }
54
55#endif /* __KERNEL__ */
56
57#endif /* _ASM_HIGHMEM_H */
58