LXR linux-old/include/asm-i386/fixmap.h

   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 <linux/config.h>
  17#include <linux/kernel.h>
  18#include <asm/apicdef.h>
  19#include <asm/page.h>
  20#ifdef CONFIG_HIGHMEM
  21#include <linux/threads.h>
  22#include <asm/kmap_types.h>
  23#endif
  24
  25/*
  26 * Here we define all the compile-time 'special' virtual
  27 * addresses. The point is to have a constant address at
  28 * compile time, but to set the physical address only
  29 * in the boot process. We allocate these special  addresses
  30 * from the end of virtual memory (0xfffff000) backwards.
  31 * Also this lets us do fail-safe vmalloc(), we
  32 * can guarantee that these special addresses and
  33 * vmalloc()-ed addresses never overlap.
  34 *
  35 * these 'compile-time allocated' memory buffers are
  36 * fixed-size 4k pages. (or larger if used with an increment
  37 * highger than 1) use fixmap_set(idx,phys) to associate
  38 * physical memory with fixmap indices.
  39 *
  40 * TLB entries of such buffers will not be flushed across
  41 * task switches.
  42 */
  43
  44/*
  45 * on UP currently we will have no trace of the fixmap mechanizm,
  46 * no page table allocations, etc. This might change in the
  47 * future, say framebuffers for the console driver(s) could be
  48 * fix-mapped?
  49 */
  50enum fixed_addresses {
  51#ifdef CONFIG_X86_LOCAL_APIC
  52        FIX_APIC_BASE,  /* local (CPU) APIC) -- required for SMP or not */
  53#endif
  54#ifdef CONFIG_X86_IO_APIC
  55        FIX_IO_APIC_BASE_0,
  56        FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
  57#endif
  58#ifdef CONFIG_X86_VISWS_APIC
  59        FIX_CO_CPU,     /* Cobalt timer */
  60        FIX_CO_APIC,    /* Cobalt APIC Redirection Table */ 
  61        FIX_LI_PCIA,    /* Lithium PCI Bridge A */
  62        FIX_LI_PCIB,    /* Lithium PCI Bridge B */
  63#endif
  64#ifndef CONFIG_X86_F00F_WORKS_OK
  65        FIX_F00F,
  66#endif
  67#ifdef CONFIG_X86_SUMMIT
  68        FIX_CYCLONE_TIMER, /*cyclone timer register*/
  69#endif 
  70#ifdef CONFIG_HIGHMEM
  71        FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
  72        FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  73#endif
  74        __end_of_permanent_fixed_addresses,
  75        /* temporary boot-time mappings, used before ioremap() is functional */
  76#define NR_FIX_BTMAPS   16
  77        FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
  78        FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS - 1,
  79        __end_of_fixed_addresses
  80};
  81
  82extern void __set_fixmap (enum fixed_addresses idx,
  83                                        unsigned long phys, pgprot_t flags);
  84
  85#define set_fixmap(idx, phys) \
  86                __set_fixmap(idx, phys, PAGE_KERNEL)
  87/*
  88 * Some hardware wants to get fixmapped without caching.
  89 */
  90#define set_fixmap_nocache(idx, phys) \
  91                __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
  92/*
  93 * used by vmalloc.c.
  94 *
  95 * Leave one empty page between vmalloc'ed areas and
  96 * the start of the fixmap, and leave one page empty
  97 * at the top of mem..
  98 */
  99#define FIXADDR_TOP     (0xffffe000UL)
 100#define __FIXADDR_SIZE  (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
 101#define FIXADDR_START   (FIXADDR_TOP - __FIXADDR_SIZE)
 102
 103#define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
 104
 105extern void __this_fixmap_does_not_exist(void);
 106
 107/*
 108 * 'index to address' translation. If anyone tries to use the idx
 109 * directly without tranlation, we catch the bug with a NULL-deference
 110 * kernel oops. Illegal ranges of incoming indices are caught too.
 111 */
 112static inline unsigned long fix_to_virt(const unsigned int idx)
 113{
 114        /*
 115         * this branch gets completely eliminated after inlining,
 116         * except when someone tries to use fixaddr indices in an
 117         * illegal way. (such as mixing up address types or using
 118         * out-of-range indices).
 119         *
 120         * If it doesn't get removed, the linker will complain
 121         * loudly with a reasonably clear error message..
 122         */
 123        if (idx >= __end_of_fixed_addresses)
 124                __this_fixmap_does_not_exist();
 125
 126        return __fix_to_virt(idx);
 127}
 128
 129#endif
 130