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 #include <linux/threads.h>
26 #include <asm/kmap_types.h>
29 #define FIXADDR_TOP ((unsigned long)(-PAGE_SIZE))
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.
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.
46 * TLB entries of such buffers will not be flushed across
49 enum fixed_addresses
{
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,
55 __end_of_fixed_addresses
58 extern void __set_fixmap(enum fixed_addresses idx
,
59 phys_addr_t phys
, pgprot_t flags
);
61 #define set_fixmap(idx, phys) \
62 __set_fixmap(idx, phys, PAGE_KERNEL)
64 * Some hardware wants to get fixmapped without caching.
66 #define set_fixmap_nocache(idx, phys) \
67 __set_fixmap(idx, phys, PAGE_KERNEL_CI)
69 #define clear_fixmap(idx) \
70 __set_fixmap(idx, 0, __pgprot(0))
72 #define __FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
73 #define FIXADDR_START (FIXADDR_TOP - __FIXADDR_SIZE)
75 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
76 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
78 extern void __this_fixmap_does_not_exist(void);
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.
85 static __always_inline
unsigned long fix_to_virt(const unsigned int idx
)
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).
93 * If it doesn't get removed, the linker will complain
94 * loudly with a reasonably clear error message..
96 if (idx
>= __end_of_fixed_addresses
)
97 __this_fixmap_does_not_exist();
99 return __fix_to_virt(idx
);
102 static inline unsigned long virt_to_fix(const unsigned long vaddr
)
104 BUG_ON(vaddr
>= FIXADDR_TOP
|| vaddr
< FIXADDR_START
);
105 return __virt_to_fix(vaddr
);
108 #endif /* !__ASSEMBLY__ */