1/*
 2 * highmem.h: virtual kernel memory mappings for high memory
 3 *
 4 * Used in CONFIG_HIGHMEM systems for memory pages which
 5 * are not addressable by direct kernel virtual addresses.
 6 *
 7 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
 8 *		      Gerhard.Wichert@pdb.siemens.de
 9 *
10 *
11 * Redesigned the x86 32-bit VM architecture to deal with
12 * up to 16 Terabyte physical memory. With current x86 CPUs
13 * we now support up to 64 Gigabytes physical RAM.
14 *
15 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
16 */
17#ifndef _ASM_HIGHMEM_H
18#define _ASM_HIGHMEM_H
19
20#ifdef __KERNEL__
21
22#include <linux/init.h>
23#include <linux/interrupt.h>
24#include <linux/uaccess.h>
25#include <asm/fixmap.h>
26
27extern pte_t *kmap_pte;
28extern pgprot_t kmap_prot;
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
53extern void *kmap_high(struct page *page);
54extern void kunmap_high(struct page *page);
55extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
56extern void __kunmap_atomic(void *kvaddr);
57
58static inline void *kmap(struct page *page)
59{
60	might_sleep();
61	if (!PageHighMem(page))
62		return page_address(page);
63	return kmap_high(page);
64}
65
66static inline void kunmap(struct page *page)
67{
68	BUG_ON(in_interrupt());
69	if (!PageHighMem(page))
70		return;
71	kunmap_high(page);
72}
73
74static inline void *__kmap_atomic(struct page *page)
75{
76	return kmap_atomic_prot(page, kmap_prot);
77}
78
79static inline struct page *kmap_atomic_to_page(void *ptr)
80{
81	unsigned long idx, vaddr = (unsigned long) ptr;
82	pte_t *pte;
83
84	if (vaddr < FIXADDR_START)
85		return virt_to_page(ptr);
86
87	idx = virt_to_fix(vaddr);
88	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
89	return pte_page(*pte);
90}
91
92#define flush_cache_kmaps()	{ flush_icache(); flush_dcache(); }
93
94#endif /* __KERNEL__ */
95
96#endif /* _ASM_HIGHMEM_H */