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 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
11 */
12
13#ifndef _ASM_FIXMAP_H
14#define _ASM_FIXMAP_H
15
16#include <asm/pgtable.h>
17#ifdef CONFIG_HIGHMEM
18#include <linux/threads.h>
19#include <asm/kmap_types.h>
20#endif
21
22/*
23 * Here we define all the compile-time 'special' virtual
24 * addresses. The point is to have a constant address at
25 * compile time, but to set the physical address only
26 * in the boot process. We allocate these special addresses
27 * from the start of the consistent memory region upwards.
28 * Also this lets us do fail-safe vmalloc(), we
29 * can guarantee that these special addresses and
30 * vmalloc()-ed addresses never overlap.
31 *
32 * these 'compile-time allocated' memory buffers are
33 * fixed-size 4k pages. (or larger if used with an increment
34 * higher than 1) use fixmap_set(idx,phys) to associate
35 * physical memory with fixmap indices.
36 */
37enum fixed_addresses {
38#ifdef CONFIG_HIGHMEM
39	/* reserved pte's for temporary kernel mappings */
40	FIX_KMAP_BEGIN,
41	FIX_KMAP_END = FIX_KMAP_BEGIN +
42		(KM_TYPE_NR * NR_CPUS * DCACHE_N_COLORS) - 1,
43#endif
44	__end_of_fixed_addresses
45};
46
47#define FIXADDR_TOP     (VMALLOC_START - PAGE_SIZE)
48#define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
49#define FIXADDR_START	((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
50
51#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
52#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
53
54#ifndef __ASSEMBLY__
55/*
56 * 'index to address' translation. If anyone tries to use the idx
57 * directly without translation, we catch the bug with a NULL-deference
58 * kernel oops. Illegal ranges of incoming indices are caught too.
59 */
60static __always_inline unsigned long fix_to_virt(const unsigned int idx)
61{
62	BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
63	return __fix_to_virt(idx);
64}
65
66static inline unsigned long virt_to_fix(const unsigned long vaddr)
67{
68	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
69	return __virt_to_fix(vaddr);
70}
71
72#endif
73
74#define kmap_get_fixmap_pte(vaddr) \
75	pte_offset_kernel( \
76		pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
77		(vaddr) \
78	)
79
80#endif
81