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 * 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 <asm/page.h>
17#ifdef CONFIG_HIGHMEM
18#include <linux/threads.h>
19#include <asm/kmap_types.h>
20#endif
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. We allocate these special addresses
27 * from the end of virtual memory (0xfffff000) backwards.
28 * Also this lets us do fail-safe vmalloc(), we
29 * can guarantee that these special addresses and
30 * vmalloc()-ed addresses never overlap.
31 *
32 * these 'compile-time allocated' memory buffers are
33 * fixed-size 4k pages. (or larger if used with an increment
34 * highger than 1) use fixmap_set(idx,phys) to associate
35 * physical memory with fixmap indices.
36 *
37 * TLB entries of such buffers will not be flushed across
38 * task switches.
39 */
40
41/*
42 * on UP currently we will have no trace of the fixmap mechanizm,
43 * no page table allocations, etc. This might change in the
44 * future, say framebuffers for the console driver(s) could be
45 * fix-mapped?
46 */
47enum fixed_addresses {
48#define FIX_N_COLOURS 8
49 FIX_CMAP_BEGIN,
50#ifdef CONFIG_MIPS_MT_SMTC
51 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS),
52#else
53 FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS,
54#endif
55#ifdef CONFIG_HIGHMEM
56 /* reserved pte's for temporary kernel mappings */
57 FIX_KMAP_BEGIN = FIX_CMAP_END + 1,
58 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
59#endif
60 __end_of_fixed_addresses
61};
62
63extern void __set_fixmap (enum fixed_addresses idx,
64 unsigned long phys, pgprot_t flags);
65
66#define set_fixmap(idx, phys) \
67 __set_fixmap(idx, phys, PAGE_KERNEL)
68/*
69 * Some hardware wants to get fixmapped without caching.
70 */
71#define set_fixmap_nocache(idx, phys) \
72 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
73/*
74 * used by vmalloc.c.
75 *
76 * Leave one empty page between vmalloc'ed areas and
77 * the start of the fixmap, and leave one page empty
78 * at the top of mem..
79 */
80#if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX)
81#define FIXADDR_TOP ((unsigned long)(long)(int)(0xff000000 - 0x20000))
82#else
83#define FIXADDR_TOP ((unsigned long)(long)(int)0xfffe0000)
84#endif
85#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
86#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
87
88#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
89#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
90
91extern void __this_fixmap_does_not_exist(void);
92
93/*
94 * 'index to address' translation. If anyone tries to use the idx
95 * directly without tranlation, we catch the bug with a NULL-deference
96 * kernel oops. Illegal ranges of incoming indices are caught too.
97 */
98static inline unsigned long fix_to_virt(const unsigned int idx)
99{
100 /*
101 * this branch gets completely eliminated after inlining,
102 * except when someone tries to use fixaddr indices in an
103 * illegal way. (such as mixing up address types or using
104 * out-of-range indices).
105 *
106 * If it doesn't get removed, the linker will complain
107 * loudly with a reasonably clear error message..
108 */
109 if (idx >= __end_of_fixed_addresses)
110 __this_fixmap_does_not_exist();
111
112 return __fix_to_virt(idx);
113}
114
115static inline unsigned long virt_to_fix(const unsigned long vaddr)
116{
117 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
118 return __virt_to_fix(vaddr);
119}
120
121/*
122 * Called from pgtable_init()
123 */
124extern void fixrange_init(unsigned long start, unsigned long end,
125 pgd_t *pgd_base);
126
127
128#endif