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 11#ifndef _ASM_FIXMAP_H 12#define _ASM_FIXMAP_H 13 14#include <linux/kernel.h> 15#include <asm/apicdef.h> 16#include <asm/page.h> 17#include <asm/vsyscall.h> 18 19/* 20 * Here we define all the compile-time 'special' virtual 21 * addresses. The point is to have a constant address at 22 * compile time, but to set the physical address only 23 * in the boot process. 24 * 25 * these 'compile-time allocated' memory buffers are 26 * fixed-size 4k pages. (or larger if used with an increment 27 * highger than 1) use fixmap_set(idx,phys) to associate 28 * physical memory with fixmap indices. 29 * 30 * TLB entries of such buffers will not be flushed across 31 * task switches. 32 */ 33 34enum fixed_addresses { 35 VSYSCALL_LAST_PAGE, 36 VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1, 37 VSYSCALL_HPET, 38 FIX_HPET_BASE, 39 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */ 40 FIX_IO_APIC_BASE_0, 41 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1, 42 __end_of_fixed_addresses 43}; 44 45extern void __set_fixmap (enum fixed_addresses idx, 46 unsigned long phys, pgprot_t flags); 47 48#define set_fixmap(idx, phys) \ 49 __set_fixmap(idx, phys, PAGE_KERNEL) 50/* 51 * Some hardware wants to get fixmapped without caching. 52 */ 53#define set_fixmap_nocache(idx, phys) \ 54 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) 55 56#define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE) 57#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 58#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 59 60/* Only covers 32bit vsyscalls currently. Need another set for 64bit. */ 61#define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL) 62#define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE) 63 64#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 65 66extern void __this_fixmap_does_not_exist(void); 67 68/* 69 * 'index to address' translation. If anyone tries to use the idx 70 * directly without translation, we catch the bug with a NULL-deference 71 * kernel oops. Illegal ranges of incoming indices are caught too. 72 */ 73static __always_inline unsigned long fix_to_virt(const unsigned int idx) 74{ 75 /* 76 * this branch gets completely eliminated after inlining, 77 * except when someone tries to use fixaddr indices in an 78 * illegal way. (such as mixing up address types or using 79 * out-of-range indices). 80 * 81 * If it doesn't get removed, the linker will complain 82 * loudly with a reasonably clear error message.. 83 */ 84 if (idx >= __end_of_fixed_addresses) 85 __this_fixmap_does_not_exist(); 86 87 return __fix_to_virt(idx); 88} 89 90#endif 91