Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 |
Paul Mundt | e4c2cfe | 2006-09-27 12:31:01 +0900 | [diff] [blame] | 28 | * from the end of P3 backwards. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 { |
Paul Mundt | 8cf1a74 | 2007-07-24 13:28:26 +0900 | [diff] [blame] | 49 | #define FIX_N_COLOURS 16 |
| 50 | FIX_CMAP_BEGIN, |
| 51 | FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Paul Mundt | 8cf1a74 | 2007-07-24 13:28:26 +0900 | [diff] [blame] | 59 | extern void __set_fixmap(enum fixed_addresses idx, |
| 60 | unsigned long phys, pgprot_t flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | #endif |