| 1 | |
| 2 | * fixmap.h: compile-time virtual memory allocation
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| 3 | *
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| 4 | * This file is subject to the terms and conditions of the GNU General Public
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| 5 | * License. See the file "COPYING" in the main directory of this archive
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| 6 | * for more details.
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| 7 | *
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| 8 | * Copyright (C) 1998 Ingo Molnar
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| 9 | *
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| 10 | * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
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| 11 |
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| 12 |
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| 13 | #ifndef _ASM_FIXMAP_H
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| 14 | #define _ASM_FIXMAP_H
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| 15 |
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| 16 | #include <asm/page.h>
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| 17 | #ifdef CONFIG_HIGHMEM
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| 18 | #include <linux/threads.h>
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| 19 | #include <asm/kmap_types.h>
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| 20 | #endif
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| 21 |
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| 22 | |
| 23 | * Here we define all the compile-time 'special' virtual
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| 24 | * addresses. The point is to have a constant address at
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| 25 | * compile time, but to set the physical address only
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| 26 | * in the boot process. We allocate these special addresses
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| 27 | * from the end of virtual memory (0xfffff000) backwards.
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| 28 | * Also this lets us do fail-safe vmalloc(), we
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| 29 | * can guarantee that these special addresses and
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| 30 | * vmalloc()-ed addresses never overlap.
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| 31 | *
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| 32 | * these 'compile-time allocated' memory buffers are
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| 33 | * fixed-size 4k pages. (or larger if used with an increment
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| 34 | * highger than 1) use fixmap_set(idx,phys) to associate
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| 35 | * physical memory with fixmap indices.
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| 36 | *
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| 37 | * TLB entries of such buffers will not be flushed across
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| 38 | * task switches.
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| 39 |
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| 40 |
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| 41 | |
| 42 | * on UP currently we will have no trace of the fixmap mechanizm,
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| 43 | * no page table allocations, etc. This might change in the
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| 44 | * future, say framebuffers for the console driver(s) could be
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| 45 | * fix-mapped?
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| 46 |
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| 47 | enum fixed_addresses {
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| 48 | #define FIX_N_COLOURS 8
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| 49 | FIX_CMAP_BEGIN,
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| 50 | #ifdef CONFIG_MIPS_MT_SMTC
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| 51 | FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS),
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| 52 | #else
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| 53 | FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS,
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| 54 | #endif
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| 55 | #ifdef CONFIG_HIGHMEM
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| 56 |
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| 57 | FIX_KMAP_BEGIN = FIX_CMAP_END + 1,
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| 58 | FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
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| 59 | #endif
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| 60 | __end_of_fixed_addresses
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| 61 | };
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| 62 |
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| 63 | extern void __set_fixmap (enum fixed_addresses idx,
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| 64 | unsigned long phys, pgprot_t flags);
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| 65 |
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| 66 | #define set_fixmap(idx, phys) \
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| 67 | __set_fixmap(idx, phys, PAGE_KERNEL)
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| 68 | |
| 69 | * Some hardware wants to get fixmapped without caching.
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| 70 |
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| 71 | #define set_fixmap_nocache(idx, phys) \
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| 72 | __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
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| 73 | |
| 74 | * used by vmalloc.c.
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| 75 | *
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| 76 | * Leave one empty page between vmalloc'ed areas and
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| 77 | * the start of the fixmap, and leave one page empty
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| 78 | * at the top of mem..
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| 79 |
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| 80 | #if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX)
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| 81 | #define FIXADDR_TOP ((unsigned long)(long)(int)(0xff000000 - 0x20000))
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| 82 | #else
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| 83 | #define FIXADDR_TOP ((unsigned long)(long)(int)0xfffe0000)
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| 84 | #endif
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| 85 | #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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| 86 | #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
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| 87 |
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| 88 | #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
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| 89 | #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
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| 90 |
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| 91 | extern void __this_fixmap_does_not_exist(void);
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| 92 |
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| 93 | |
| 94 | * 'index to address' translation. If anyone tries to use the idx
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| 95 | * directly without tranlation, we catch the bug with a NULL-deference
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| 96 | * kernel oops. Illegal ranges of incoming indices are caught too.
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| 97 |
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| 98 | static inline unsigned long fix_to_virt(const unsigned int idx)
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| 99 | {
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| 100 | |
| 101 | * this branch gets completely eliminated after inlining,
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| 102 | * except when someone tries to use fixaddr indices in an
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| 103 | * illegal way. (such as mixing up address types or using
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| 104 | * out-of-range indices).
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| 105 | *
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| 106 | * If it doesn't get removed, the linker will complain
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| 107 | * loudly with a reasonably clear error message..
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| 108 |
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| 109 | if (idx >= __end_of_fixed_addresses)
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| 110 | __this_fixmap_does_not_exist();
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| 111 |
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| 112 | return __fix_to_virt(idx);
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| 113 | }
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| 114 |
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| 115 | static inline unsigned long virt_to_fix(const unsigned long vaddr)
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| 116 | {
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| 117 | BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
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| 118 | return __virt_to_fix(vaddr);
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| 119 | }
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| 120 |
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| 121 | |
| 122 | * Called from pgtable_init()
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| 123 |
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| 124 | extern void fixrange_init(unsigned long start, unsigned long end,
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| 125 | pgd_t *pgd_base);
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| 126 |
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| 127 |
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| 128 | #endif
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