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 /* 50 * The FIX_CMAP entries are used by kmap_coherent() to get virtual 51 * addresses which are of a known color, and so their values are 52 * important. __fix_to_virt(FIX_CMAP_END - n) must give an address 53 * which is the same color as a page (n<<PAGE_SHIFT). 54 */ 55 #define FIX_N_COLOURS 8 56 FIX_CMAP_BEGIN, 57 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1, 58 59 #ifdef CONFIG_HIGHMEM 60 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ 61 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, 62 #endif 63 64 /* 65 * FIX_IOREMAP entries are useful for mapping physical address 66 * space before ioremap() is useable, e.g. really early in boot 67 * before kmalloc() is working. 68 */ 69 #define FIX_N_IOREMAPS 32 70 FIX_IOREMAP_BEGIN, 71 FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS, 72 73 __end_of_fixed_addresses 74 }; 75 76 extern void __set_fixmap(enum fixed_addresses idx, 77 unsigned long phys, pgprot_t flags); 78 extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags); 79 80 #define set_fixmap(idx, phys) \ 81 __set_fixmap(idx, phys, PAGE_KERNEL) 82 /* 83 * Some hardware wants to get fixmapped without caching. 84 */ 85 #define set_fixmap_nocache(idx, phys) \ 86 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) 87 /* 88 * used by vmalloc.c. 89 * 90 * Leave one empty page between vmalloc'ed areas and 91 * the start of the fixmap, and leave one page empty 92 * at the top of mem.. 93 */ 94 #ifdef CONFIG_SUPERH32 95 #define FIXADDR_TOP (P4SEG - PAGE_SIZE) 96 #else 97 #define FIXADDR_TOP (0xff000000 - PAGE_SIZE) 98 #endif 99 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 100 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 101 102 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 103 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 104 105 extern void __this_fixmap_does_not_exist(void); 106 107 /* 108 * 'index to address' translation. If anyone tries to use the idx 109 * directly without tranlation, we catch the bug with a NULL-deference 110 * kernel oops. Illegal ranges of incoming indices are caught too. 111 */ 112 static inline unsigned long fix_to_virt(const unsigned int idx) 113 { 114 /* 115 * this branch gets completely eliminated after inlining, 116 * except when someone tries to use fixaddr indices in an 117 * illegal way. (such as mixing up address types or using 118 * out-of-range indices). 119 * 120 * If it doesn't get removed, the linker will complain 121 * loudly with a reasonably clear error message.. 122 */ 123 if (idx >= __end_of_fixed_addresses) 124 __this_fixmap_does_not_exist(); 125 126 return __fix_to_virt(idx); 127 } 128 129 static inline unsigned long virt_to_fix(const unsigned long vaddr) 130 { 131 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 132 return __virt_to_fix(vaddr); 133 } 134 #endif 135