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1da177e4 LT |
1 | #ifndef __UM_FIXMAP_H |
2 | #define __UM_FIXMAP_H | |
3 | ||
4 | #include <linux/config.h> | |
5 | #include <asm/kmap_types.h> | |
6 | #include <asm/archparam.h> | |
7 | ||
8 | /* | |
9 | * Here we define all the compile-time 'special' virtual | |
10 | * addresses. The point is to have a constant address at | |
11 | * compile time, but to set the physical address only | |
12 | * in the boot process. We allocate these special addresses | |
13 | * from the end of virtual memory (0xfffff000) backwards. | |
14 | * Also this lets us do fail-safe vmalloc(), we | |
15 | * can guarantee that these special addresses and | |
16 | * vmalloc()-ed addresses never overlap. | |
17 | * | |
18 | * these 'compile-time allocated' memory buffers are | |
19 | * fixed-size 4k pages. (or larger if used with an increment | |
20 | * highger than 1) use fixmap_set(idx,phys) to associate | |
21 | * physical memory with fixmap indices. | |
22 | * | |
23 | * TLB entries of such buffers will not be flushed across | |
24 | * task switches. | |
25 | */ | |
26 | ||
27 | /* | |
28 | * on UP currently we will have no trace of the fixmap mechanizm, | |
29 | * no page table allocations, etc. This might change in the | |
30 | * future, say framebuffers for the console driver(s) could be | |
31 | * fix-mapped? | |
32 | */ | |
33 | enum fixed_addresses { | |
34 | #ifdef CONFIG_HIGHMEM | |
35 | FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ | |
36 | FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, | |
37 | #endif | |
38 | __end_of_fixed_addresses | |
39 | }; | |
40 | ||
41 | extern void __set_fixmap (enum fixed_addresses idx, | |
42 | unsigned long phys, pgprot_t flags); | |
43 | ||
44 | #define set_fixmap(idx, phys) \ | |
45 | __set_fixmap(idx, phys, PAGE_KERNEL) | |
46 | /* | |
47 | * Some hardware wants to get fixmapped without caching. | |
48 | */ | |
49 | #define set_fixmap_nocache(idx, phys) \ | |
50 | __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) | |
51 | /* | |
52 | * used by vmalloc.c. | |
53 | * | |
54 | * Leave one empty page between vmalloc'ed areas and | |
55 | * the start of the fixmap, and leave one page empty | |
56 | * at the top of mem.. | |
57 | */ | |
58 | extern unsigned long get_kmem_end(void); | |
59 | ||
60 | #define FIXADDR_TOP (get_kmem_end() - 0x2000) | |
61 | #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) | |
62 | #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) | |
63 | ||
64 | #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) | |
65 | #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) | |
66 | ||
67 | extern void __this_fixmap_does_not_exist(void); | |
68 | ||
69 | /* | |
70 | * 'index to address' translation. If anyone tries to use the idx | |
71 | * directly without tranlation, we catch the bug with a NULL-deference | |
72 | * kernel oops. Illegal ranges of incoming indices are caught too. | |
73 | */ | |
74 | static inline unsigned long fix_to_virt(const unsigned int idx) | |
75 | { | |
76 | /* | |
77 | * this branch gets completely eliminated after inlining, | |
78 | * except when someone tries to use fixaddr indices in an | |
79 | * illegal way. (such as mixing up address types or using | |
80 | * out-of-range indices). | |
81 | * | |
82 | * If it doesn't get removed, the linker will complain | |
83 | * loudly with a reasonably clear error message.. | |
84 | */ | |
85 | if (idx >= __end_of_fixed_addresses) | |
86 | __this_fixmap_does_not_exist(); | |
87 | ||
88 | return __fix_to_virt(idx); | |
89 | } | |
90 | ||
91 | static inline unsigned long virt_to_fix(const unsigned long vaddr) | |
92 | { | |
93 | BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); | |
94 | return __virt_to_fix(vaddr); | |
95 | } | |
96 | ||
97 | #endif |