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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 | |
e4c2cfee | 28 | * from the end of P3 backwards. |
1da177e4 LT |
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 mechanizm, | |
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 { | |
8cf1a743 PM |
49 | #define FIX_N_COLOURS 16 |
50 | FIX_CMAP_BEGIN, | |
51 | FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS, | |
1da177e4 LT |
52 | #ifdef CONFIG_HIGHMEM |
53 | FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ | |
54 | FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, | |
55 | #endif | |
56 | __end_of_fixed_addresses | |
57 | }; | |
58 | ||
8cf1a743 PM |
59 | extern void __set_fixmap(enum fixed_addresses idx, |
60 | unsigned long phys, pgprot_t flags); | |
1da177e4 LT |
61 | |
62 | #define set_fixmap(idx, phys) \ | |
63 | __set_fixmap(idx, phys, PAGE_KERNEL) | |
64 | /* | |
65 | * Some hardware wants to get fixmapped without caching. | |
66 | */ | |
67 | #define set_fixmap_nocache(idx, phys) \ | |
68 | __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) | |
69 | /* | |
70 | * used by vmalloc.c. | |
71 | * | |
72 | * Leave one empty page between vmalloc'ed areas and | |
73 | * the start of the fixmap, and leave one page empty | |
74 | * at the top of mem.. | |
75 | */ | |
76 | #define FIXADDR_TOP (P4SEG - PAGE_SIZE) | |
77 | #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) | |
78 | #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) | |
79 | ||
80 | #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) | |
81 | #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) | |
82 | ||
83 | extern void __this_fixmap_does_not_exist(void); | |
84 | ||
85 | /* | |
86 | * 'index to address' translation. If anyone tries to use the idx | |
87 | * directly without tranlation, we catch the bug with a NULL-deference | |
88 | * kernel oops. Illegal ranges of incoming indices are caught too. | |
89 | */ | |
90 | static inline unsigned long fix_to_virt(const unsigned int idx) | |
91 | { | |
92 | /* | |
93 | * this branch gets completely eliminated after inlining, | |
94 | * except when someone tries to use fixaddr indices in an | |
95 | * illegal way. (such as mixing up address types or using | |
96 | * out-of-range indices). | |
97 | * | |
98 | * If it doesn't get removed, the linker will complain | |
99 | * loudly with a reasonably clear error message.. | |
100 | */ | |
101 | if (idx >= __end_of_fixed_addresses) | |
102 | __this_fixmap_does_not_exist(); | |
103 | ||
104 | return __fix_to_virt(idx); | |
105 | } | |
106 | ||
107 | static inline unsigned long virt_to_fix(const unsigned long vaddr) | |
108 | { | |
109 | BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); | |
110 | return __virt_to_fix(vaddr); | |
111 | } | |
1da177e4 | 112 | #endif |