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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 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
11 */
12
13#ifndef _ASM_FIXMAP_H
14#define _ASM_FIXMAP_H
15
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/kernel.h>
17#include <asm/page.h>
18#ifdef CONFIG_HIGHMEM
19#include <linux/threads.h>
20#include <asm/kmap_types.h>
21#endif
22
23/*
24 * Here we define all the compile-time 'special' virtual
25 * addresses. The point is to have a constant address at
26 * compile time, but to set the physical address only
27 * in the boot process. We allocate these special addresses
Paul Mundte4c2cfe2006-09-27 12:31:01 +090028 * from the end of P3 backwards.
Linus Torvalds1da177e2005-04-16 15:20:36 -070029 * Also this lets us do fail-safe vmalloc(), we
30 * can guarantee that these special addresses and
31 * vmalloc()-ed addresses never overlap.
32 *
33 * these 'compile-time allocated' memory buffers are
34 * fixed-size 4k pages. (or larger if used with an increment
35 * highger than 1) use fixmap_set(idx,phys) to associate
36 * physical memory with fixmap indices.
37 *
38 * TLB entries of such buffers will not be flushed across
39 * task switches.
40 */
41
42/*
43 * on UP currently we will have no trace of the fixmap mechanizm,
44 * no page table allocations, etc. This might change in the
45 * future, say framebuffers for the console driver(s) could be
46 * fix-mapped?
47 */
48enum fixed_addresses {
Paul Mundt8cf1a742007-07-24 13:28:26 +090049#define FIX_N_COLOURS 16
50 FIX_CMAP_BEGIN,
51 FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS,
Stuart Menefycbaa1182007-11-30 17:06:36 +090052 FIX_UNCACHED,
Linus Torvalds1da177e2005-04-16 15:20:36 -070053#ifdef CONFIG_HIGHMEM
54 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
55 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
56#endif
57 __end_of_fixed_addresses
58};
59
Paul Mundt8cf1a742007-07-24 13:28:26 +090060extern void __set_fixmap(enum fixed_addresses idx,
61 unsigned long phys, pgprot_t flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
63#define set_fixmap(idx, phys) \
64 __set_fixmap(idx, phys, PAGE_KERNEL)
65/*
66 * Some hardware wants to get fixmapped without caching.
67 */
68#define set_fixmap_nocache(idx, phys) \
69 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
70/*
71 * used by vmalloc.c.
72 *
73 * Leave one empty page between vmalloc'ed areas and
74 * the start of the fixmap, and leave one page empty
75 * at the top of mem..
76 */
Paul Mundt5a4a5bd2007-11-08 18:55:39 +090077#ifdef CONFIG_SUPERH32
Linus Torvalds1da177e2005-04-16 15:20:36 -070078#define FIXADDR_TOP (P4SEG - PAGE_SIZE)
Paul Mundt5a4a5bd2007-11-08 18:55:39 +090079#else
80#define FIXADDR_TOP (0xff000000 - PAGE_SIZE)
81#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070082#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
83#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
84
85#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
86#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
87
88extern void __this_fixmap_does_not_exist(void);
89
90/*
91 * 'index to address' translation. If anyone tries to use the idx
92 * directly without tranlation, we catch the bug with a NULL-deference
93 * kernel oops. Illegal ranges of incoming indices are caught too.
94 */
95static inline unsigned long fix_to_virt(const unsigned int idx)
96{
97 /*
98 * this branch gets completely eliminated after inlining,
99 * except when someone tries to use fixaddr indices in an
100 * illegal way. (such as mixing up address types or using
101 * out-of-range indices).
102 *
103 * If it doesn't get removed, the linker will complain
104 * loudly with a reasonably clear error message..
105 */
106 if (idx >= __end_of_fixed_addresses)
107 __this_fixmap_does_not_exist();
108
109 return __fix_to_virt(idx);
110}
111
112static inline unsigned long virt_to_fix(const unsigned long vaddr)
113{
114 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
115 return __virt_to_fix(vaddr);
116}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117#endif