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 */
37 enum 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 (XCHAL_KSEG_CACHED_VADDR - 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 */
60 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
61 {
62 /* Check if this memory layout is broken because fixmap overlaps page
63 * table.
64 */
65 BUILD_BUG_ON(FIXADDR_START <
66 TLBTEMP_BASE_1 + TLBTEMP_SIZE);
67 BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
68 return __fix_to_virt(idx);
69 }
70
71 static inline unsigned long virt_to_fix(const unsigned long vaddr)
72 {
73 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
74 return __virt_to_fix(vaddr);
75 }
76
77 #endif
78
79 #define kmap_get_fixmap_pte(vaddr) \
80 pte_offset_kernel( \
81 pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
82 (vaddr) \
83 )
84
85 #endif