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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/kernel.h>
15#include <asm/apicdef.h>
16#include <asm/page.h>
17#include <asm/vsyscall.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018
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 *
Jiri Kosinabdb345a2007-07-21 17:11:21 +020025 * These 'compile-time allocated' memory buffers are
26 * fixed-size 4k pages (or larger if used with an increment
27 * higher than 1). Use set_fixmap(idx,phys) to associate
Linus Torvalds1da177e2005-04-16 15:20:36 -070028 * 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,
Yinghai Lu18a8bd92007-07-15 23:37:59 -070038 FIX_DBGP_BASE,
39 FIX_EARLYCON_MEM_BASE,
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 FIX_HPET_BASE,
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
Linus Torvalds1da177e2005-04-16 15:20:36 -070042 FIX_IO_APIC_BASE_0,
43 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 __end_of_fixed_addresses
45};
46
47extern void __set_fixmap (enum fixed_addresses idx,
48 unsigned long phys, pgprot_t flags);
49
50#define set_fixmap(idx, phys) \
51 __set_fixmap(idx, phys, PAGE_KERNEL)
52/*
53 * Some hardware wants to get fixmapped without caching.
54 */
55#define set_fixmap_nocache(idx, phys) \
56 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
57
58#define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE)
59#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
60#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
61
62/* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
63#define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL)
64#define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
65
66#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
67
68extern void __this_fixmap_does_not_exist(void);
69
70/*
71 * 'index to address' translation. If anyone tries to use the idx
72 * directly without translation, we catch the bug with a NULL-deference
73 * kernel oops. Illegal ranges of incoming indices are caught too.
74 */
Ingo Molnar652050a2006-01-14 13:21:30 -080075static __always_inline unsigned long fix_to_virt(const unsigned int idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -070076{
77 /*
78 * this branch gets completely eliminated after inlining,
79 * except when someone tries to use fixaddr indices in an
80 * illegal way. (such as mixing up address types or using
81 * out-of-range indices).
82 *
83 * If it doesn't get removed, the linker will complain
84 * loudly with a reasonably clear error message..
85 */
86 if (idx >= __end_of_fixed_addresses)
87 __this_fixmap_does_not_exist();
88
Yinghai Lu18a8bd92007-07-15 23:37:59 -070089 return __fix_to_virt(idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -070090}
91
92#endif