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
37 enum 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
52 extern 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
69 extern 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 */
fix_to_virt(const unsigned int idx)76 extern 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