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1da177e4 LT |
1 | /* |
2 | * fixmap.h: compile-time virtual memory allocation | |
3 | * | |
4 | * This file is subject to the terms and conditions of the GNU General Public | |
5 | * License. See the file "COPYING" in the main directory of this archive | |
6 | * for more details. | |
7 | * | |
8 | * Copyright (C) 1998 Ingo Molnar | |
9 | * | |
10 | * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999 | |
11 | */ | |
12 | ||
13 | #ifndef _ASM_FIXMAP_H | |
14 | #define _ASM_FIXMAP_H | |
15 | ||
1da177e4 LT |
16 | #include <linux/kernel.h> |
17 | #include <asm/page.h> | |
18 | #ifdef CONFIG_HIGHMEM | |
19 | #include <linux/threads.h> | |
20 | #include <asm/kmap_types.h> | |
21 | #endif | |
22 | ||
23 | /* | |
24 | * Here we define all the compile-time 'special' virtual | |
25 | * addresses. The point is to have a constant address at | |
26 | * compile time, but to set the physical address only | |
27 | * in the boot process. We allocate these special addresses | |
28 | * from the top of unused virtual memory (0xfd000000 - 1 page) backwards. | |
29 | * Also this lets us do fail-safe vmalloc(), we | |
30 | * can guarantee that these special addresses and | |
31 | * vmalloc()-ed addresses never overlap. | |
32 | * | |
33 | * these 'compile-time allocated' memory buffers are | |
34 | * fixed-size 4k pages. (or larger if used with an increment | |
35 | * highger than 1) use fixmap_set(idx,phys) to associate | |
36 | * physical memory with fixmap indices. | |
37 | * | |
38 | * TLB entries of such buffers will not be flushed across | |
39 | * task switches. | |
40 | */ | |
41 | ||
42 | /* | |
43 | * on UP currently we will have no trace of the fixmap mechanism, | |
44 | * no page table allocations, etc. This might change in the | |
45 | * future, say framebuffers for the console driver(s) could be | |
46 | * fix-mapped? | |
47 | */ | |
48 | enum fixed_addresses { | |
49 | FIX_HOLE, | |
50 | #ifdef CONFIG_HIGHMEM | |
51 | FIX_KMAP_BEGIN, | |
52 | FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, | |
53 | #endif | |
54 | __end_of_fixed_addresses | |
55 | }; | |
56 | ||
57 | extern void __set_fixmap (enum fixed_addresses idx, | |
58 | unsigned long phys, pgprot_t flags); | |
59 | ||
60 | #define set_fixmap(idx, phys) \ | |
61 | __set_fixmap(idx, phys, PAGE_KERNEL) | |
62 | /* | |
63 | * Some hardware wants to get fixmapped without caching. | |
64 | */ | |
65 | #define set_fixmap_nocache(idx, phys) \ | |
66 | __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) | |
67 | /* | |
68 | * used by vmalloc.c. | |
69 | * | |
70 | * Leave one empty page between IO pages at 0xfd000000 and | |
71 | * the start of the fixmap. | |
72 | */ | |
73 | #define FIXADDR_TOP (0xfcfff000UL) | |
74 | #define FIXADDR_SIZE ((__end_of_fixed_addresses) << PAGE_SHIFT) | |
75 | #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) | |
76 | ||
77 | #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) | |
78 | #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) | |
79 | ||
80 | extern void __this_fixmap_does_not_exist(void); | |
81 | ||
82 | /* | |
83 | * 'index to address' translation. If anyone tries to use the idx | |
84 | * directly without tranlation, we catch the bug with a NULL-deference | |
85 | * kernel oops. Illegal ranges of incoming indices are caught too. | |
86 | */ | |
87 | static inline unsigned long fix_to_virt(const unsigned int idx) | |
88 | { | |
89 | /* | |
90 | * this branch gets completely eliminated after inlining, | |
91 | * except when someone tries to use fixaddr indices in an | |
92 | * illegal way. (such as mixing up address types or using | |
93 | * out-of-range indices). | |
94 | * | |
95 | * If it doesn't get removed, the linker will complain | |
96 | * loudly with a reasonably clear error message.. | |
97 | */ | |
98 | if (idx >= __end_of_fixed_addresses) | |
99 | __this_fixmap_does_not_exist(); | |
100 | ||
101 | return __fix_to_virt(idx); | |
102 | } | |
103 | ||
104 | static inline unsigned long virt_to_fix(const unsigned long vaddr) | |
105 | { | |
106 | BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); | |
107 | return __virt_to_fix(vaddr); | |
108 | } | |
109 | ||
110 | #endif |