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 */ 47enum 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 63extern void __set_fixmap (enum fixed_addresses idx, 64 unsigned long phys, pgprot_t flags); 65 66#define set_fixmap(idx, phys) \ 67 __set_fixmap(idx, phys, PAGE_KERNEL) 68/* 69 * Some hardware wants to get fixmapped without caching. 70 */ 71#define set_fixmap_nocache(idx, phys) \ 72 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) 73/* 74 * used by vmalloc.c. 75 * 76 * Leave one empty page between vmalloc'ed areas and 77 * the start of the fixmap, and leave one page empty 78 * at the top of mem.. 79 */ 80#if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX) 81#define FIXADDR_TOP ((unsigned long)(long)(int)(0xff000000 - 0x20000)) 82#elif defined(CONFIG_BCM47XX) 83#define FIXADDR_TOP ((unsigned long)(long)(int)0xf0000000) 84#else 85#define FIXADDR_TOP ((unsigned long)(long)(int)0xfffe0000) 86#endif 87#define FIXADDR_SIZE (__end_of_fixed_addresses << (VALIAS_PAGE_SHIFT)) 88#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 89 90#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 91#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 92 93/* macro to map the fixmaped vaddr, by trying to avoid 94 * vaddr's which potentially could cause Virtual Alias 95 */ 96static inline unsigned long fix_to_virt_noalias(const unsigned int x, unsigned long pfn) 97{ 98 unsigned long vaddr = __fix_to_virt(x); 99 unsigned long poffset = (pfn << PAGE_SHIFT) & VALIAS_PAGE_OFFSET_MASK; 100 unsigned long voffset = vaddr & VALIAS_PAGE_OFFSET_MASK; 101 102 return ((!voffset || (poffset >= voffset)) ? (vaddr | poffset):(vaddr | poffset | VALIAS_PAGE_SIZE)); 103} 104 105extern 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 */ 112static 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 129static 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} 134 135/* 136 * Called from pgtable_init() 137 */ 138extern void fixrange_init(unsigned long start, unsigned long end, 139 pgd_t *pgd_base); 140 141 142#endif 143