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 #ifdef CONFIG_IOREMAP_FIXED 65 /* 66 * FIX_IOREMAP entries are useful for mapping physical address 67 * space before ioremap() is useable, e.g. really early in boot 68 * before kmalloc() is working. 69 */ 70 #define FIX_N_IOREMAPS 32 71 FIX_IOREMAP_BEGIN, 72 FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1, 73 #endif 74 75 __end_of_fixed_addresses 76 }; 77 78 extern void __set_fixmap(enum fixed_addresses idx, 79 unsigned long phys, pgprot_t flags); 80 extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags); 81 82 #define set_fixmap(idx, phys) \ 83 __set_fixmap(idx, phys, PAGE_KERNEL) 84 /* 85 * Some hardware wants to get fixmapped without caching. 86 */ 87 #define set_fixmap_nocache(idx, phys) \ 88 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) 89 /* 90 * used by vmalloc.c. 91 * 92 * Leave one empty page between vmalloc'ed areas and 93 * the start of the fixmap, and leave one page empty 94 * at the top of mem.. 95 */ 96 #ifdef CONFIG_SUPERH32 97 #define FIXADDR_TOP (P4SEG - PAGE_SIZE) 98 #else 99 #define FIXADDR_TOP ((unsigned long)(-PAGE_SIZE)) 100 #endif 101 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 102 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 103 104 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 105 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 106 107 extern void __this_fixmap_does_not_exist(void); 108 109 /* 110 * 'index to address' translation. If anyone tries to use the idx 111 * directly without tranlation, we catch the bug with a NULL-deference 112 * kernel oops. Illegal ranges of incoming indices are caught too. 113 */ 114 static inline unsigned long fix_to_virt(const unsigned int idx) 115 { 116 /* 117 * this branch gets completely eliminated after inlining, 118 * except when someone tries to use fixaddr indices in an 119 * illegal way. (such as mixing up address types or using 120 * out-of-range indices). 121 * 122 * If it doesn't get removed, the linker will complain 123 * loudly with a reasonably clear error message.. 124 */ 125 if (idx >= __end_of_fixed_addresses) 126 __this_fixmap_does_not_exist(); 127 128 return __fix_to_virt(idx); 129 } 130 131 static inline unsigned long virt_to_fix(const unsigned long vaddr) 132 { 133 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 134 return __virt_to_fix(vaddr); 135 } 136 #endif 137