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2f2f371f MS |
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 | ||
27 | extern pte_t *kmap_pte; | |
28 | extern pgprot_t kmap_prot; | |
29 | extern 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 | extern void *kmap_high(struct page *page); | |
54 | extern void kunmap_high(struct page *page); | |
55 | extern void *kmap_atomic_prot(struct page *page, pgprot_t prot); | |
56 | extern void __kunmap_atomic(void *kvaddr); | |
57 | ||
58 | static 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 | ||
66 | static inline void kunmap(struct page *page) | |
67 | { | |
68 | BUG_ON(in_interrupt()); | |
69 | if (!PageHighMem(page)) | |
70 | return; | |
71 | kunmap_high(page); | |
72 | } | |
73 | ||
ffed2b4f | 74 | static inline void *kmap_atomic(struct page *page) |
2f2f371f MS |
75 | { |
76 | return kmap_atomic_prot(page, kmap_prot); | |
77 | } | |
78 | ||
79 | static 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 */ |