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 16 #include <linux/kernel.h> 17 #include <linux/threads.h> 18 #include <asm/page.h> 19 #ifdef CONFIG_HIGHMEM 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 end of P3 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 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 { 49 #define FIX_N_COLOURS 8 50 FIX_CMAP_BEGIN, 51 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS), 52 FIX_UNCACHED, 53 #ifdef CONFIG_HIGHMEM 54 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ 55 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, 56 #endif 57 __end_of_fixed_addresses 58 }; 59 60 extern void __set_fixmap(enum fixed_addresses idx, 61 unsigned long phys, pgprot_t flags); 62 63 #define set_fixmap(idx, phys) \ 64 __set_fixmap(idx, phys, PAGE_KERNEL) 65 /* 66 * Some hardware wants to get fixmapped without caching. 67 */ 68 #define set_fixmap_nocache(idx, phys) \ 69 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) 70 /* 71 * used by vmalloc.c. 72 * 73 * Leave one empty page between vmalloc'ed areas and 74 * the start of the fixmap, and leave one page empty 75 * at the top of mem.. 76 */ 77 #ifdef CONFIG_SUPERH32 78 #define FIXADDR_TOP (P4SEG - PAGE_SIZE) 79 #else 80 #define FIXADDR_TOP (0xff000000 - PAGE_SIZE) 81 #endif 82 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 83 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 84 85 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 86 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 87 88 extern void __this_fixmap_does_not_exist(void); 89 90 /* 91 * 'index to address' translation. If anyone tries to use the idx 92 * directly without tranlation, we catch the bug with a NULL-deference 93 * kernel oops. Illegal ranges of incoming indices are caught too. 94 */ 95 static inline unsigned long fix_to_virt(const unsigned int idx) 96 { 97 /* 98 * this branch gets completely eliminated after inlining, 99 * except when someone tries to use fixaddr indices in an 100 * illegal way. (such as mixing up address types or using 101 * out-of-range indices). 102 * 103 * If it doesn't get removed, the linker will complain 104 * loudly with a reasonably clear error message.. 105 */ 106 if (idx >= __end_of_fixed_addresses) 107 __this_fixmap_does_not_exist(); 108 109 return __fix_to_virt(idx); 110 } 111 112 static inline unsigned long virt_to_fix(const unsigned long vaddr) 113 { 114 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 115 return __virt_to_fix(vaddr); 116 } 117 #endif 118