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fixmap.h
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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  * Copyright 2008 Freescale Semiconductor Inc.
11  * Port to powerpc added by Kumar Gala
12  *
13  * Copyright 2011 Michal Simek <[email protected]>
14  * Copyright 2011 PetaLogix Qld Pty Ltd
15  * Port to Microblaze
16  */
17 
18 #ifndef _ASM_FIXMAP_H
19 #define _ASM_FIXMAP_H
20 
21 #ifndef __ASSEMBLY__
22 #include <linux/kernel.h>
23 #include <asm/page.h>
24 #ifdef CONFIG_HIGHMEM
25 #include <linux/threads.h>
26 #include <asm/kmap_types.h>
27 #endif
28 
29 #define FIXADDR_TOP ((unsigned long)(-PAGE_SIZE))
30 
31 /*
32  * Here we define all the compile-time 'special' virtual
33  * addresses. The point is to have a constant address at
34  * compile time, but to set the physical address only
35  * in the boot process. We allocate these special addresses
36  * from the end of virtual memory (0xfffff000) backwards.
37  * Also this lets us do fail-safe vmalloc(), we
38  * can guarantee that these special addresses and
39  * vmalloc()-ed addresses never overlap.
40  *
41  * these 'compile-time allocated' memory buffers are
42  * fixed-size 4k pages. (or larger if used with an increment
43  * highger than 1) use fixmap_set(idx,phys) to associate
44  * physical memory with fixmap indices.
45  *
46  * TLB entries of such buffers will not be flushed across
47  * task switches.
48  */
51 #ifdef CONFIG_HIGHMEM
52  FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
53  FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * num_possible_cpus()) - 1,
54 #endif
56 };
57 
58 extern void __set_fixmap(enum fixed_addresses idx,
60 
61 #define set_fixmap(idx, phys) \
62  __set_fixmap(idx, phys, PAGE_KERNEL)
63 /*
64  * Some hardware wants to get fixmapped without caching.
65  */
66 #define set_fixmap_nocache(idx, phys) \
67  __set_fixmap(idx, phys, PAGE_KERNEL_CI)
68 
69 #define clear_fixmap(idx) \
70  __set_fixmap(idx, 0, __pgprot(0))
71 
72 #define __FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
73 #define FIXADDR_START (FIXADDR_TOP - __FIXADDR_SIZE)
74 
75 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
76 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
77 
78 extern void __this_fixmap_does_not_exist(void);
79 
80 /*
81  * 'index to address' translation. If anyone tries to use the idx
82  * directly without tranlation, we catch the bug with a NULL-deference
83  * kernel oops. Illegal ranges of incoming indices are caught too.
84  */
85 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
86 {
87  /*
88  * this branch gets completely eliminated after inlining,
89  * except when someone tries to use fixaddr indices in an
90  * illegal way. (such as mixing up address types or using
91  * out-of-range indices).
92  *
93  * If it doesn't get removed, the linker will complain
94  * loudly with a reasonably clear error message..
95  */
96  if (idx >= __end_of_fixed_addresses)
98 
99  return __fix_to_virt(idx);
100 }
101 
102 static inline unsigned long virt_to_fix(const unsigned long vaddr)
103 {
104  BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
105  return __virt_to_fix(vaddr);
106 }
107 
108 #endif /* !__ASSEMBLY__ */
109 #endif