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#include <asm/vsyscall.h> 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. 27 * 28 * these 'compile-time allocated' memory buffers are 29 * fixed-size 4k pages. (or larger if used with an increment 30 * highger than 1) use fixmap_set(idx,phys) to associate 31 * physical memory with fixmap indices. 32 * 33 * TLB entries of such buffers will not be flushed across 34 * task switches. 35 */ 36 37enum fixed_addresses { 38 VSYSCALL_LAST_PAGE, 39 VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1, 40 VSYSCALL_HPET, 41 FIX_HPET_BASE, 42#ifdef CONFIG_X86_LOCAL_APIC 43 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */ 44#endif 45#ifdef CONFIG_X86_IO_APIC 46 FIX_IO_APIC_BASE_0, 47 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1, 48#endif 49 __end_of_fixed_addresses 50}; 51 52extern void __set_fixmap (enum fixed_addresses idx, 53 unsigned long phys, pgprot_t flags); 54 55#define set_fixmap(idx, phys) \ 56 __set_fixmap(idx, phys, PAGE_KERNEL) 57/* 58 * Some hardware wants to get fixmapped without caching. 59 */ 60#define set_fixmap_nocache(idx, phys) \ 61 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) 62 63#define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE) 64#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 65#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 66 67#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 68 69extern void __this_fixmap_does_not_exist(void); 70 71/* 72 * 'index to address' translation. If anyone tries to use the idx 73 * directly without tranlation, we catch the bug with a NULL-deference 74 * kernel oops. Illegal ranges of incoming indices are caught too. 75 */ 76extern inline unsigned long fix_to_virt(const unsigned int idx) 77{ 78 /* 79 * this branch gets completely eliminated after inlining, 80 * except when someone tries to use fixaddr indices in an 81 * illegal way. (such as mixing up address types or using 82 * out-of-range indices). 83 * 84 * If it doesn't get removed, the linker will complain 85 * loudly with a reasonably clear error message.. 86 */ 87 if (idx >= __end_of_fixed_addresses) 88 __this_fixmap_does_not_exist(); 89 90 return __fix_to_virt(idx); 91} 92 93#endif 94