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