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 #include <spaces.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 28 * from the end of virtual memory (0xfffff000) 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 #ifdef CONFIG_MIPS_MT_SMTC 52 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS * 2), 53 #else 54 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * 2), 55 #endif 56 #ifdef CONFIG_HIGHMEM 57 /* reserved pte's for temporary kernel mappings */ 58 FIX_KMAP_BEGIN = FIX_CMAP_END + 1, 59 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, 60 #endif 61 __end_of_fixed_addresses 62 }; 63 64 /* 65 * used by vmalloc.c. 66 * 67 * Leave one empty page between vmalloc'ed areas and 68 * the start of the fixmap, and leave one page empty 69 * at the top of mem.. 70 */ 71 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 72 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 73 74 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 75 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 76 77 extern void __this_fixmap_does_not_exist(void); 78 79 /* 80 * 'index to address' translation. If anyone tries to use the idx 81 * directly without tranlation, we catch the bug with a NULL-deference 82 * kernel oops. Illegal ranges of incoming indices are caught too. 83 */ 84 static inline unsigned long fix_to_virt(const unsigned int idx) 85 { 86 /* 87 * this branch gets completely eliminated after inlining, 88 * except when someone tries to use fixaddr indices in an 89 * illegal way. (such as mixing up address types or using 90 * out-of-range indices). 91 * 92 * If it doesn't get removed, the linker will complain 93 * loudly with a reasonably clear error message.. 94 */ 95 if (idx >= __end_of_fixed_addresses) 96 __this_fixmap_does_not_exist(); 97 98 return __fix_to_virt(idx); 99 } 100 101 static inline unsigned long virt_to_fix(const unsigned long vaddr) 102 { 103 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 104 return __virt_to_fix(vaddr); 105 } 106 107 #define kmap_get_fixmap_pte(vaddr) \ 108 pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), (vaddr)) 109 110 /* 111 * Called from pgtable_init() 112 */ 113 extern void fixrange_init(unsigned long start, unsigned long end, 114 pgd_t *pgd_base); 115 116 117 #endif 118