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 <asm/page.h> 17 #ifdef CONFIG_HIGHMEM 18 #include <linux/threads.h> 19 #include <asm/kmap_types.h> 20 #endif 21 22 /* 23 * Here we define all the compile-time 'special' virtual 24 * addresses. The point is to have a constant address at 25 * compile time, but to set the physical address only 26 * in the boot process. We allocate these special addresses 27 * from the end of virtual memory (0xfffff000) backwards. 28 * Also this lets us do fail-safe vmalloc(), we 29 * can guarantee that these special addresses and 30 * vmalloc()-ed addresses never overlap. 31 * 32 * these 'compile-time allocated' memory buffers are 33 * fixed-size 4k pages. (or larger if used with an increment 34 * highger than 1) use fixmap_set(idx,phys) to associate 35 * physical memory with fixmap indices. 36 * 37 * TLB entries of such buffers will not be flushed across 38 * task switches. 39 */ 40 41 /* 42 * on UP currently we will have no trace of the fixmap mechanizm, 43 * no page table allocations, etc. This might change in the 44 * future, say framebuffers for the console driver(s) could be 45 * fix-mapped? 46 */ 47 enum fixed_addresses { 48 #define FIX_N_COLOURS 8 49 FIX_CMAP_BEGIN, 50 #ifdef CONFIG_MIPS_MT_SMTC 51 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS), 52 #else 53 FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS, 54 #endif 55 #ifdef CONFIG_HIGHMEM 56 /* reserved pte's for temporary kernel mappings */ 57 FIX_KMAP_BEGIN = FIX_CMAP_END + 1, 58 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, 59 #endif 60 __end_of_fixed_addresses 61 }; 62 63 /* 64 * used by vmalloc.c. 65 * 66 * Leave one empty page between vmalloc'ed areas and 67 * the start of the fixmap, and leave one page empty 68 * at the top of mem.. 69 */ 70 #if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX) 71 #define FIXADDR_TOP ((unsigned long)(long)(int)(0xff000000 - 0x20000)) 72 #else 73 #define FIXADDR_TOP ((unsigned long)(long)(int)0xfffe0000) 74 #endif 75 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 76 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 77 78 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 79 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 80 81 extern void __this_fixmap_does_not_exist(void); 82 83 /* 84 * 'index to address' translation. If anyone tries to use the idx 85 * directly without tranlation, we catch the bug with a NULL-deference 86 * kernel oops. Illegal ranges of incoming indices are caught too. 87 */ 88 static inline unsigned long fix_to_virt(const unsigned int idx) 89 { 90 /* 91 * this branch gets completely eliminated after inlining, 92 * except when someone tries to use fixaddr indices in an 93 * illegal way. (such as mixing up address types or using 94 * out-of-range indices). 95 * 96 * If it doesn't get removed, the linker will complain 97 * loudly with a reasonably clear error message.. 98 */ 99 if (idx >= __end_of_fixed_addresses) 100 __this_fixmap_does_not_exist(); 101 102 return __fix_to_virt(idx); 103 } 104 105 static inline unsigned long virt_to_fix(const unsigned long vaddr) 106 { 107 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 108 return __virt_to_fix(vaddr); 109 } 110 111 /* 112 * Called from pgtable_init() 113 */ 114 extern void fixrange_init(unsigned long start, unsigned long end, 115 pgd_t *pgd_base); 116 117 118 #endif 119
