| 1 | /*
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| 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 <linux/config.h>
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| 17 | #include <linux/kernel.h>
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| 18 | #include <asm/apic.h>
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| 19 | #include <asm/page.h>
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| 20 | #ifdef CONFIG_HIGHMEM
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| 21 | #include <linux/threads.h>
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| 22 | #include <asm/kmap_types.h>
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| 23 | #endif
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| 24 |
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| 25 | /*
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| 26 | * Here we define all the compile-time 'special' virtual
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| 27 | * addresses. The point is to have a constant address at
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| 28 | * compile time, but to set the physical address only
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| 29 | * in the boot process. We allocate these special addresses
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| 30 | * from the end of virtual memory (0xfffff000) backwards.
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| 31 | * Also this lets us do fail-safe vmalloc(), we
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| 32 | * can guarantee that these special addresses and
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| 33 | * vmalloc()-ed addresses never overlap.
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| 34 | *
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| 35 | * these 'compile-time allocated' memory buffers are
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| 36 | * fixed-size 4k pages. (or larger if used with an increment
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| 37 | * highger than 1) use fixmap_set(idx,phys) to associate
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| 38 | * physical memory with fixmap indices.
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| 39 | *
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| 40 | * TLB entries of such buffers will not be flushed across
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| 41 | * task switches.
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| 42 | */
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| 43 |
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| 44 | /*
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| 45 | * on UP currently we will have no trace of the fixmap mechanizm,
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| 46 | * no page table allocations, etc. This might change in the
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| 47 | * future, say framebuffers for the console driver(s) could be
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| 48 | * fix-mapped?
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| 49 | */
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| 50 | enum fixed_addresses {
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| 51 | #ifdef CONFIG_X86_LOCAL_APIC
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| 52 | FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
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| 53 | #endif
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| 54 | #ifdef CONFIG_X86_IO_APIC
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| 55 | FIX_IO_APIC_BASE_0,
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| 56 | FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
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| 57 | #endif
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| 58 | #ifdef CONFIG_X86_VISWS_APIC
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| 59 | FIX_CO_CPU, /* Cobalt timer */
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| 60 | FIX_CO_APIC, /* Cobalt APIC Redirection Table */
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| 61 | FIX_LI_PCIA, /* Lithium PCI Bridge A */
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| 62 | FIX_LI_PCIB, /* Lithium PCI Bridge B */
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| 63 | #endif
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| 64 | #ifdef CONFIG_HIGHMEM
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| 65 | FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
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| 66 | FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
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| 67 | #endif
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| 68 | __end_of_fixed_addresses
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| 69 | };
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| 70 |
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| 71 | extern void set_fixmap (enum fixed_addresses idx, unsigned long phys);
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| 72 |
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| 73 | /*
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| 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 | #define FIXADDR_TOP (0xffffe000UL)
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| 81 | #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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| 82 | #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
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| 83 |
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| 84 | #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
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| 85 |
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| 86 | extern void __this_fixmap_does_not_exist(void);
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| 87 |
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| 88 | #if 0
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| 89 | /*
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| 90 | * 'index to address' translation. If anyone tries to use the idx
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| 91 | * directly without tranlation, we catch the bug with a NULL-deference
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| 92 | * kernel oops. Illegal ranges of incoming indices are caught too.
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| 93 | */
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| 94 | extern inline unsigned long fix_to_virt(const unsigned int idx)
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| 95 | {
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| 96 | /*
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| 97 | * this branch gets completely eliminated after inlining,
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| 98 | * except when someone tries to use fixaddr indices in an
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| 99 | * illegal way. (such as mixing up address types or using
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| 100 | * out-of-range indices).
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| 101 | *
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| 102 | * If it doesn't get removed, the linker will complain
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| 103 | * loudly with a reasonably clear error message..
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| 104 | */
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| 105 | if (idx >= __end_of_fixed_addresses)
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| 106 | __this_fixmap_does_not_exist();
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| 107 |
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| 108 | return __fix_to_virt(idx);
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| 109 | }
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| 110 | #endif
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| 111 |
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| 112 | #endif
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