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 */
47 enum 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
63 /*
64 * used by vmalloc.c.
65 *
66 * Leave one empty page between vmalloc'ed areas and
67 * the start of the fixmap, and leave one page empty
68 * at the top of mem..
69 */
70 #if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX)
71 #define FIXADDR_TOP ((unsigned long)(long)(int)(0xff000000 - 0x20000))
72 #else
73 #define FIXADDR_TOP ((unsigned long)(long)(int)0xfffe0000)
74 #endif
75 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
76 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
77
78 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
79 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
80
81 extern void __this_fixmap_does_not_exist(void);
82
83 /*
84 * 'index to address' translation. If anyone tries to use the idx
85 * directly without tranlation, we catch the bug with a NULL-deference
86 * kernel oops. Illegal ranges of incoming indices are caught too.
87 */
fix_to_virt(const unsigned int idx)88 static inline unsigned long fix_to_virt(const unsigned int idx)
89 {
90 /*
91 * this branch gets completely eliminated after inlining,
92 * except when someone tries to use fixaddr indices in an
93 * illegal way. (such as mixing up address types or using
94 * out-of-range indices).
95 *
96 * If it doesn't get removed, the linker will complain
97 * loudly with a reasonably clear error message..
98 */
99 if (idx >= __end_of_fixed_addresses)
100 __this_fixmap_does_not_exist();
101
102 return __fix_to_virt(idx);
103 }
104
virt_to_fix(const unsigned long vaddr)105 static inline unsigned long virt_to_fix(const unsigned long vaddr)
106 {
107 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
108 return __virt_to_fix(vaddr);
109 }
110
111 /*
112 * Called from pgtable_init()
113 */
114 extern void fixrange_init(unsigned long start, unsigned long end,
115 pgd_t *pgd_base);
116
117
118 #endif
119