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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 | ||
11 | #ifndef _ASM_FIXMAP_H | |
12 | #define _ASM_FIXMAP_H | |
13 | ||
1da177e4 LT |
14 | #include <linux/kernel.h> |
15 | #include <asm/apicdef.h> | |
16 | #include <asm/page.h> | |
17 | #include <asm/vsyscall.h> | |
1da177e4 LT |
18 | |
19 | /* | |
20 | * Here we define all the compile-time 'special' virtual | |
21 | * addresses. The point is to have a constant address at | |
22 | * compile time, but to set the physical address only | |
23 | * in the boot process. | |
24 | * | |
25 | * these 'compile-time allocated' memory buffers are | |
26 | * fixed-size 4k pages. (or larger if used with an increment | |
27 | * highger than 1) use fixmap_set(idx,phys) to associate | |
28 | * physical memory with fixmap indices. | |
29 | * | |
30 | * TLB entries of such buffers will not be flushed across | |
31 | * task switches. | |
32 | */ | |
33 | ||
34 | enum fixed_addresses { | |
35 | VSYSCALL_LAST_PAGE, | |
36 | VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1, | |
37 | VSYSCALL_HPET, | |
18a8bd94 YL |
38 | FIX_DBGP_BASE, |
39 | FIX_EARLYCON_MEM_BASE, | |
1da177e4 | 40 | FIX_HPET_BASE, |
1da177e4 | 41 | FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */ |
1da177e4 LT |
42 | FIX_IO_APIC_BASE_0, |
43 | FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1, | |
1da177e4 LT |
44 | __end_of_fixed_addresses |
45 | }; | |
46 | ||
47 | extern void __set_fixmap (enum fixed_addresses idx, | |
48 | unsigned long phys, pgprot_t flags); | |
49 | ||
50 | #define set_fixmap(idx, phys) \ | |
51 | __set_fixmap(idx, phys, PAGE_KERNEL) | |
52 | /* | |
53 | * Some hardware wants to get fixmapped without caching. | |
54 | */ | |
55 | #define set_fixmap_nocache(idx, phys) \ | |
56 | __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) | |
57 | ||
58 | #define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE) | |
59 | #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) | |
60 | #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) | |
61 | ||
62 | /* Only covers 32bit vsyscalls currently. Need another set for 64bit. */ | |
63 | #define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL) | |
64 | #define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE) | |
65 | ||
66 | #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) | |
67 | ||
68 | extern void __this_fixmap_does_not_exist(void); | |
69 | ||
70 | /* | |
71 | * 'index to address' translation. If anyone tries to use the idx | |
72 | * directly without translation, we catch the bug with a NULL-deference | |
73 | * kernel oops. Illegal ranges of incoming indices are caught too. | |
74 | */ | |
652050ae | 75 | static __always_inline unsigned long fix_to_virt(const unsigned int idx) |
1da177e4 LT |
76 | { |
77 | /* | |
78 | * this branch gets completely eliminated after inlining, | |
79 | * except when someone tries to use fixaddr indices in an | |
80 | * illegal way. (such as mixing up address types or using | |
81 | * out-of-range indices). | |
82 | * | |
83 | * If it doesn't get removed, the linker will complain | |
84 | * loudly with a reasonably clear error message.. | |
85 | */ | |
86 | if (idx >= __end_of_fixed_addresses) | |
87 | __this_fixmap_does_not_exist(); | |
88 | ||
18a8bd94 | 89 | return __fix_to_virt(idx); |
1da177e4 LT |
90 | } |
91 | ||
92 | #endif |