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-rw-r--r--include/asm-um/fixmap.h97
1 files changed, 97 insertions, 0 deletions
diff --git a/include/asm-um/fixmap.h b/include/asm-um/fixmap.h
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1#ifndef __UM_FIXMAP_H
2#define __UM_FIXMAP_H
3
4#include <linux/config.h>
5#include <asm/kmap_types.h>
6#include <asm/archparam.h>
7
8/*
9 * Here we define all the compile-time 'special' virtual
10 * addresses. The point is to have a constant address at
11 * compile time, but to set the physical address only
12 * in the boot process. We allocate these special addresses
13 * from the end of virtual memory (0xfffff000) backwards.
14 * Also this lets us do fail-safe vmalloc(), we
15 * can guarantee that these special addresses and
16 * vmalloc()-ed addresses never overlap.
17 *
18 * these 'compile-time allocated' memory buffers are
19 * fixed-size 4k pages. (or larger if used with an increment
20 * highger than 1) use fixmap_set(idx,phys) to associate
21 * physical memory with fixmap indices.
22 *
23 * TLB entries of such buffers will not be flushed across
24 * task switches.
25 */
26
27/*
28 * on UP currently we will have no trace of the fixmap mechanizm,
29 * no page table allocations, etc. This might change in the
30 * future, say framebuffers for the console driver(s) could be
31 * fix-mapped?
32 */
33enum fixed_addresses {
34#ifdef CONFIG_HIGHMEM
35 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
36 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
37#endif
38 __end_of_fixed_addresses
39};
40
41extern void __set_fixmap (enum fixed_addresses idx,
42 unsigned long phys, pgprot_t flags);
43
44#define set_fixmap(idx, phys) \
45 __set_fixmap(idx, phys, PAGE_KERNEL)
46/*
47 * Some hardware wants to get fixmapped without caching.
48 */
49#define set_fixmap_nocache(idx, phys) \
50 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
51/*
52 * used by vmalloc.c.
53 *
54 * Leave one empty page between vmalloc'ed areas and
55 * the start of the fixmap, and leave one page empty
56 * at the top of mem..
57 */
58extern unsigned long get_kmem_end(void);
59
60#define FIXADDR_TOP (get_kmem_end() - 0x2000)
61#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
62#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
63
64#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
65#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
66
67extern void __this_fixmap_does_not_exist(void);
68
69/*
70 * 'index to address' translation. If anyone tries to use the idx
71 * directly without tranlation, we catch the bug with a NULL-deference
72 * kernel oops. Illegal ranges of incoming indices are caught too.
73 */
74static inline unsigned long fix_to_virt(const unsigned int idx)
75{
76 /*
77 * this branch gets completely eliminated after inlining,
78 * except when someone tries to use fixaddr indices in an
79 * illegal way. (such as mixing up address types or using
80 * out-of-range indices).
81 *
82 * If it doesn't get removed, the linker will complain
83 * loudly with a reasonably clear error message..
84 */
85 if (idx >= __end_of_fixed_addresses)
86 __this_fixmap_does_not_exist();
87
88 return __fix_to_virt(idx);
89}
90
91static inline unsigned long virt_to_fix(const unsigned long vaddr)
92{
93 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
94 return __virt_to_fix(vaddr);
95}
96
97#endif