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