2 * fixmap.h: compile-time virtual memory allocation
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
8 * Copyright (C) 1998 Ingo Molnar
10 * Copyright 2008 Freescale Semiconductor Inc.
11 * Port to powerpc added by Kumar Gala
13 * Copyright 2011 Michal Simek <monstr@monstr.eu>
14 * Copyright 2011 PetaLogix Qld Pty Ltd
22 #include <linux/kernel.h>
25 #define FIXADDR_TOP ((unsigned long)(-PAGE_SIZE))
28 * Here we define all the compile-time 'special' virtual
29 * addresses. The point is to have a constant address at
30 * compile time, but to set the physical address only
31 * in the boot process. We allocate these special addresses
32 * from the end of virtual memory (0xfffff000) backwards.
33 * Also this lets us do fail-safe vmalloc(), we
34 * can guarantee that these special addresses and
35 * vmalloc()-ed addresses never overlap.
37 * these 'compile-time allocated' memory buffers are
38 * fixed-size 4k pages. (or larger if used with an increment
39 * highger than 1) use fixmap_set(idx,phys) to associate
40 * physical memory with fixmap indices.
42 * TLB entries of such buffers will not be flushed across
45 enum fixed_addresses
{
47 __end_of_fixed_addresses
50 extern void __set_fixmap(enum fixed_addresses idx
,
51 phys_addr_t phys
, pgprot_t flags
);
53 #define set_fixmap(idx, phys) \
54 __set_fixmap(idx, phys, PAGE_KERNEL)
56 * Some hardware wants to get fixmapped without caching.
58 #define set_fixmap_nocache(idx, phys) \
59 __set_fixmap(idx, phys, PAGE_KERNEL_CI)
61 #define clear_fixmap(idx) \
62 __set_fixmap(idx, 0, __pgprot(0))
64 #define __FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
65 #define FIXADDR_START (FIXADDR_TOP - __FIXADDR_SIZE)
67 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
68 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
70 extern void __this_fixmap_does_not_exist(void);
73 * 'index to address' translation. If anyone tries to use the idx
74 * directly without tranlation, we catch the bug with a NULL-deference
75 * kernel oops. Illegal ranges of incoming indices are caught too.
77 static __always_inline
unsigned long fix_to_virt(const unsigned int idx
)
80 * this branch gets completely eliminated after inlining,
81 * except when someone tries to use fixaddr indices in an
82 * illegal way. (such as mixing up address types or using
83 * out-of-range indices).
85 * If it doesn't get removed, the linker will complain
86 * loudly with a reasonably clear error message..
88 if (idx
>= __end_of_fixed_addresses
)
89 __this_fixmap_does_not_exist();
91 return __fix_to_virt(idx
);
94 static inline unsigned long virt_to_fix(const unsigned long vaddr
)
96 BUG_ON(vaddr
>= FIXADDR_TOP
|| vaddr
< FIXADDR_START
);
97 return __virt_to_fix(vaddr
);
100 #endif /* !__ASSEMBLY__ */
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