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/config.h> 17#include <linux/kernel.h> 18#include <asm/apicdef.h> 19#include <asm/page.h> 20#ifdef CONFIG_HIGHMEM 21#include <linux/threads.h> 22#include <asm/kmap_types.h> 23#endif 24 25/* 26 * Here we define all the compile-time 'special' virtual 27 * addresses. The point is to have a constant address at 28 * compile time, but to set the physical address only 29 * in the boot process. We allocate these special addresses 30 * from the end of virtual memory (0xfffff000) backwards. 31 * Also this lets us do fail-safe vmalloc(), we 32 * can guarantee that these special addresses and 33 * vmalloc()-ed addresses never overlap. 34 * 35 * these 'compile-time allocated' memory buffers are 36 * fixed-size 4k pages. (or larger if used with an increment 37 * highger than 1) use fixmap_set(idx,phys) to associate 38 * physical memory with fixmap indices. 39 * 40 * TLB entries of such buffers will not be flushed across 41 * task switches. 42 */ 43 44/* 45 * on UP currently we will have no trace of the fixmap mechanizm, 46 * no page table allocations, etc. This might change in the 47 * future, say framebuffers for the console driver(s) could be 48 * fix-mapped? 49 */ 50enum fixed_addresses { 51#ifdef CONFIG_X86_LOCAL_APIC 52 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */ 53#endif 54#ifdef CONFIG_X86_IO_APIC 55 FIX_IO_APIC_BASE_0, 56 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1, 57#endif 58#ifdef CONFIG_X86_VISWS_APIC 59 FIX_CO_CPU, /* Cobalt timer */ 60 FIX_CO_APIC, /* Cobalt APIC Redirection Table */ 61 FIX_LI_PCIA, /* Lithium PCI Bridge A */ 62 FIX_LI_PCIB, /* Lithium PCI Bridge B */ 63#endif 64#ifdef CONFIG_HIGHMEM 65 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ 66 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, 67#endif 68 __end_of_fixed_addresses 69}; 70 71extern void __set_fixmap (enum fixed_addresses idx, 72 unsigned long phys, pgprot_t flags); 73 74#define set_fixmap(idx, phys) \ 75 __set_fixmap(idx, phys, PAGE_KERNEL) 76/* 77 * Some hardware wants to get fixmapped without caching. 78 */ 79#define set_fixmap_nocache(idx, phys) \ 80 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) 81/* 82 * used by vmalloc.c. 83 * 84 * Leave one empty page between vmalloc'ed areas and 85 * the start of the fixmap, and leave one page empty 86 * at the top of mem.. 87 */ 88#define FIXADDR_TOP (0xffffe000UL) 89#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 90#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 91 92#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 93 94extern void __this_fixmap_does_not_exist(void); 95 96/* 97 * 'index to address' translation. If anyone tries to use the idx 98 * directly without tranlation, we catch the bug with a NULL-deference 99 * kernel oops. Illegal ranges of incoming indices are caught too. 100 */ 101extern inline unsigned long fix_to_virt(const unsigned int idx) 102{ 103 /* 104 * this branch gets completely eliminated after inlining, 105 * except when someone tries to use fixaddr indices in an 106 * illegal way. (such as mixing up address types or using 107 * out-of-range indices). 108 * 109 * If it doesn't get removed, the linker will complain 110 * loudly with a reasonably clear error message.. 111 */ 112 if (idx >= __end_of_fixed_addresses) 113 __this_fixmap_does_not_exist(); 114 115 return __fix_to_virt(idx); 116} 117 118#endif 119