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 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
11 */
12
13#ifndef _ASM_FIXMAP_H
14#define _ASM_FIXMAP_H
15
16#include <linux/config.h>
17#include <linux/kernel.h>
18#include <asm/apicdef.h>
19#include <asm/page.h>
20#include <asm/vsyscall.h>
21
22/*
23 * Here we define all the compile-time 'special' virtual
24 * addresses. The point is to have a constant address at
25 * compile time, but to set the physical address only
26 * in the boot process.
27 *
28 * these 'compile-time allocated' memory buffers are
29 * fixed-size 4k pages. (or larger if used with an increment
30 * highger than 1) use fixmap_set(idx,phys) to associate
31 * physical memory with fixmap indices.
32 *
33 * TLB entries of such buffers will not be flushed across
34 * task switches.
35 */
36
37enum fixed_addresses {
38	VSYSCALL_LAST_PAGE,
39	VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
40	VSYSCALL_HPET,
41	FIX_HPET_BASE,
42#ifdef CONFIG_X86_LOCAL_APIC
43	FIX_APIC_BASE,	/* local (CPU) APIC) -- required for SMP or not */
44#endif
45#ifdef CONFIG_X86_IO_APIC
46	FIX_IO_APIC_BASE_0,
47	FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
48#endif
49	__end_of_fixed_addresses
50};
51
52extern void __set_fixmap (enum fixed_addresses idx,
53					unsigned long phys, pgprot_t flags);
54
55#define set_fixmap(idx, phys) \
56		__set_fixmap(idx, phys, PAGE_KERNEL)
57/*
58 * Some hardware wants to get fixmapped without caching.
59 */
60#define set_fixmap_nocache(idx, phys) \
61		__set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
62
63#define FIXADDR_TOP	(VSYSCALL_END-PAGE_SIZE)
64#define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
65#define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)
66
67#define __fix_to_virt(x)	(FIXADDR_TOP - ((x) << PAGE_SHIFT))
68
69extern void __this_fixmap_does_not_exist(void);
70
71/*
72 * 'index to address' translation. If anyone tries to use the idx
73 * directly without tranlation, we catch the bug with a NULL-deference
74 * kernel oops. Illegal ranges of incoming indices are caught too.
75 */
76extern inline unsigned long fix_to_virt(const unsigned int idx)
77{
78	/*
79	 * this branch gets completely eliminated after inlining,
80	 * except when someone tries to use fixaddr indices in an
81	 * illegal way. (such as mixing up address types or using
82	 * out-of-range indices).
83	 *
84	 * If it doesn't get removed, the linker will complain
85	 * loudly with a reasonably clear error message..
86	 */
87	if (idx >= __end_of_fixed_addresses)
88		__this_fixmap_does_not_exist();
89
90        return __fix_to_virt(idx);
91}
92
93#endif
94