1#ifndef _LINUX_HIGHMEM_H
2#define _LINUX_HIGHMEM_H
3
4#include <linux/config.h>
5#include <asm/pgalloc.h>
6
7#ifdef CONFIG_HIGHMEM
8
9extern struct page *highmem_start_page;
10
11#include <asm/highmem.h>
12
13/* declarations for linux/mm/highmem.c */
14unsigned int nr_free_highpages(void);
15
16extern struct buffer_head *create_bounce(int rw, struct buffer_head * bh_orig);
17
18static inline char *bh_kmap(struct buffer_head *bh)
19{
20	return kmap(bh->b_page) + bh_offset(bh);
21}
22
23static inline void bh_kunmap(struct buffer_head *bh)
24{
25	kunmap(bh->b_page);
26}
27
28/*
29 * remember to add offset! and never ever reenable interrupts between a
30 * bh_kmap_irq and bh_kunmap_irq!!
31 */
32static inline char *bh_kmap_irq(struct buffer_head *bh, unsigned long *flags)
33{
34	unsigned long addr;
35
36	__save_flags(*flags);
37
38	/*
39	 * could be low
40	 */
41	if (!PageHighMem(bh->b_page))
42		return bh->b_data;
43
44	/*
45	 * it's a highmem page
46	 */
47	__cli();
48	addr = (unsigned long) kmap_atomic(bh->b_page, KM_BH_IRQ);
49
50	if (addr & ~PAGE_MASK)
51		BUG();
52
53	return (char *) addr + bh_offset(bh);
54}
55
56static inline void bh_kunmap_irq(char *buffer, unsigned long *flags)
57{
58	unsigned long ptr = (unsigned long) buffer & PAGE_MASK;
59
60	kunmap_atomic((void *) ptr, KM_BH_IRQ);
61	__restore_flags(*flags);
62}
63
64#else /* CONFIG_HIGHMEM */
65
66static inline unsigned int nr_free_highpages(void) { return 0; }
67
68static inline void *kmap(struct page *page) { return page_address(page); }
69
70#define kunmap(page) do { } while (0)
71
72#define kmap_atomic(page,idx)		kmap(page)
73#define kunmap_atomic(page,idx)		kunmap(page)
74
75#define bh_kmap(bh)			((bh)->b_data)
76#define bh_kunmap(bh)			do { } while (0)
77#define bh_kmap_irq(bh, flags)		((bh)->b_data)
78#define bh_kunmap_irq(bh, flags)	do { *(flags) = 0; } while (0)
79
80#endif /* CONFIG_HIGHMEM */
81
82/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
83static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
84{
85	void *addr = kmap_atomic(page, KM_USER0);
86	clear_user_page(addr, vaddr);
87	kunmap_atomic(addr, KM_USER0);
88}
89
90static inline void clear_highpage(struct page *page)
91{
92	clear_page(kmap(page));
93	kunmap(page);
94}
95
96/*
97 * Same but also flushes aliased cache contents to RAM.
98 */
99static inline void memclear_highpage_flush(struct page *page, unsigned int offset, unsigned int size)
100{
101	char *kaddr;
102
103	if (offset + size > PAGE_SIZE)
104		out_of_line_bug();
105	kaddr = kmap(page);
106	memset(kaddr + offset, 0, size);
107	flush_dcache_page(page);
108	flush_page_to_ram(page);
109	kunmap(page);
110}
111
112static inline void copy_user_highpage(struct page *to, struct page *from, unsigned long vaddr)
113{
114	char *vfrom, *vto;
115
116	vfrom = kmap_atomic(from, KM_USER0);
117	vto = kmap_atomic(to, KM_USER1);
118	copy_user_page(vto, vfrom, vaddr);
119	kunmap_atomic(vfrom, KM_USER0);
120	kunmap_atomic(vto, KM_USER1);
121}
122
123#endif /* _LINUX_HIGHMEM_H */
124