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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/config.h>
15#include <linux/kernel.h>
16#include <asm/apicdef.h>
17#include <asm/page.h>
18#include <asm/vsyscall.h>
19#include <asm/vsyscall32.h>
20
21/*
22 * Here we define all the compile-time 'special' virtual
23 * addresses. The point is to have a constant address at
24 * compile time, but to set the physical address only
25 * in the boot process.
26 *
27 * these 'compile-time allocated' memory buffers are
28 * fixed-size 4k pages. (or larger if used with an increment
29 * highger than 1) use fixmap_set(idx,phys) to associate
30 * physical memory with fixmap indices.
31 *
32 * TLB entries of such buffers will not be flushed across
33 * task switches.
34 */
35
36enum fixed_addresses {
37 VSYSCALL_LAST_PAGE,
38 VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
39 VSYSCALL_HPET,
40 FIX_HPET_BASE,
41#ifdef CONFIG_X86_LOCAL_APIC
42 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
43#endif
44#ifdef CONFIG_X86_IO_APIC
45 FIX_IO_APIC_BASE_0,
46 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
47#endif
48 __end_of_fixed_addresses
49};
50
51extern void __set_fixmap (enum fixed_addresses idx,
52 unsigned long phys, pgprot_t flags);
53
54#define set_fixmap(idx, phys) \
55 __set_fixmap(idx, phys, PAGE_KERNEL)
56/*
57 * Some hardware wants to get fixmapped without caching.
58 */
59#define set_fixmap_nocache(idx, phys) \
60 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
61
62#define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE)
63#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
64#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
65
66/* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
67#define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL)
68#define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
69
70#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
71
72extern void __this_fixmap_does_not_exist(void);
73
74/*
75 * 'index to address' translation. If anyone tries to use the idx
76 * directly without translation, we catch the bug with a NULL-deference
77 * kernel oops. Illegal ranges of incoming indices are caught too.
78 */
79extern inline unsigned long fix_to_virt(const unsigned int idx)
80{
81 /*
82 * this branch gets completely eliminated after inlining,
83 * except when someone tries to use fixaddr indices in an
84 * illegal way. (such as mixing up address types or using
85 * out-of-range indices).
86 *
87 * If it doesn't get removed, the linker will complain
88 * loudly with a reasonably clear error message..
89 */
90 if (idx >= __end_of_fixed_addresses)
91 __this_fixmap_does_not_exist();
92
93 return __fix_to_virt(idx);
94}
95
96#endif