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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/efi.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 * higher than 1). Use set_fixmap(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_DBGP_BASE,
40 FIX_EARLYCON_MEM_BASE,
41 FIX_HPET_BASE,
42 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
43 FIX_IO_APIC_BASE_0,
44 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
45 FIX_EFI_IO_MAP_LAST_PAGE,
46 FIX_EFI_IO_MAP_FIRST_PAGE = FIX_EFI_IO_MAP_LAST_PAGE+MAX_EFI_IO_PAGES-1,
47#ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
48 FIX_OHCI1394_BASE,
49#endif
50 __end_of_fixed_addresses
51};
52
53extern void __set_fixmap (enum fixed_addresses idx,
54 unsigned long phys, pgprot_t flags);
55
56#define set_fixmap(idx, phys) \
57 __set_fixmap(idx, phys, PAGE_KERNEL)
58/*
59 * Some hardware wants to get fixmapped without caching.
60 */
61#define set_fixmap_nocache(idx, phys) \
62 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
63
64#define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE)
65#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
66#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
67
68/* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
69#define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL)
70#define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
71
72#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
73
74extern void __this_fixmap_does_not_exist(void);
75
76/*
77 * 'index to address' translation. If anyone tries to use the idx
78 * directly without translation, we catch the bug with a NULL-deference
79 * kernel oops. Illegal ranges of incoming indices are caught too.
80 */
81static __always_inline unsigned long fix_to_virt(const unsigned int idx)
82{
83 /*
84 * this branch gets completely eliminated after inlining,
85 * except when someone tries to use fixaddr indices in an
86 * illegal way. (such as mixing up address types or using
87 * out-of-range indices).
88 *
89 * If it doesn't get removed, the linker will complain
90 * loudly with a reasonably clear error message..
91 */
92 if (idx >= __end_of_fixed_addresses)
93 __this_fixmap_does_not_exist();
94
95 return __fix_to_virt(idx);
96}
97
98#endif