highmem.h revision 850f6ac316cf84bba63fdb775c897834eccbfaa3 
1/*
2 * highmem.h: virtual kernel memory mappings for high memory
3 *
4 * PowerPC version, stolen from the i386 version.
5 *
6 * Used in CONFIG_HIGHMEM systems for memory pages which
7 * are not addressable by direct kernel virtual addresses.
8 *
9 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
10 *		      Gerhard.Wichert@pdb.siemens.de
11 *
12 *
13 * Redesigned the x86 32-bit VM architecture to deal with
14 * up to 16 Terrabyte physical memory. With current x86 CPUs
15 * we now support up to 64 Gigabytes physical RAM.
16 *
17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
18 */
19
20#ifndef _ASM_HIGHMEM_H
21#define _ASM_HIGHMEM_H
22
23#ifdef __KERNEL__
24
25#include <linux/interrupt.h>
26#include <asm/kmap_types.h>
27#include <asm/tlbflush.h>
28#include <asm/page.h>
29#include <asm/fixmap.h>
30
31extern pte_t *kmap_pte;
32extern pgprot_t kmap_prot;
33extern pte_t *pkmap_page_table;
34
35/*
36 * Right now we initialize only a single pte table. It can be extended
37 * easily, subsequent pte tables have to be allocated in one physical
38 * chunk of RAM.
39 */
40/*
41 * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte
42 * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP
43 * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP
44 * in case of 16K/64K/256K page sizes.
45 */
46#ifdef CONFIG_PPC_4K_PAGES
47#define PKMAP_ORDER	PTE_SHIFT
48#else
49#define PKMAP_ORDER	9
50#endif
51#define LAST_PKMAP	(1 << PKMAP_ORDER)
52#ifndef CONFIG_PPC_4K_PAGES
53#define PKMAP_BASE	(FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
54#else
55#define PKMAP_BASE	((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
56#endif
57#define LAST_PKMAP_MASK	(LAST_PKMAP-1)
58#define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
59#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
60
61extern void *kmap_high(struct page *page);
62extern void kunmap_high(struct page *page);
63extern void *kmap_atomic_prot(struct page *page, enum km_type type,
64			      pgprot_t prot);
65extern void kunmap_atomic(void *kvaddr, enum km_type type);
66
67static inline void *kmap(struct page *page)
68{
69	might_sleep();
70	if (!PageHighMem(page))
71		return page_address(page);
72	return kmap_high(page);
73}
74
75static inline void kunmap(struct page *page)
76{
77	BUG_ON(in_interrupt());
78	if (!PageHighMem(page))
79		return;
80	kunmap_high(page);
81}
82
83static inline void *kmap_atomic(struct page *page, enum km_type type)
84{
85	return kmap_atomic_prot(page, type, kmap_prot);
86}
87
88static inline struct page *kmap_atomic_to_page(void *ptr)
89{
90	unsigned long idx, vaddr = (unsigned long) ptr;
91	pte_t *pte;
92
93	if (vaddr < FIXADDR_START)
94		return virt_to_page(ptr);
95
96	idx = virt_to_fix(vaddr);
97	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
98	return pte_page(*pte);
99}
100
101
102#define flush_cache_kmaps()	flush_cache_all()
103
104#endif /* __KERNEL__ */
105
106#endif /* _ASM_HIGHMEM_H */
107