include/asm-x86_64/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
  11 #ifndef _ASM_FIXMAP_H
  12 #define _ASM_FIXMAP_H
  13
  14 #include <linux/kernel.h>
  15 #include <asm/apicdef.h>
  16 #include <asm/page.h>
  17 #include <asm/vsyscall.h>
  18
  19 /*
  20  * Here we define all the compile-time 'special' virtual
  21  * addresses. The point is to have a constant address at
  22  * compile time, but to set the physical address only
  23  * in the boot process.
  24  *
  25  * these 'compile-time allocated' memory buffers are
  26  * fixed-size 4k pages. (or larger if used with an increment
  27  * highger than 1) use fixmap_set(idx,phys) to associate
  28  * physical memory with fixmap indices.
  29  *
  30  * TLB entries of such buffers will not be flushed across
  31  * task switches.
  32  */
  33
  34 enum fixed_addresses {
  35         VSYSCALL_LAST_PAGE,
  36         VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
  37         VSYSCALL_HPET,
  38         FIX_HPET_BASE,
  39         FIX_APIC_BASE,  /* local (CPU) APIC) -- required for SMP or not */
  40         FIX_IO_APIC_BASE_0,
  41         FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
  42         __end_of_fixed_addresses
  43 };
  44
  45 extern void __set_fixmap (enum fixed_addresses idx,
  46                                         unsigned long phys, pgprot_t flags);
  47
  48 #define set_fixmap(idx, phys) \
  49                 __set_fixmap(idx, phys, PAGE_KERNEL)
  50 /*
  51  * Some hardware wants to get fixmapped without caching.
  52  */
  53 #define set_fixmap_nocache(idx, phys) \
  54                 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
  55
  56 #define FIXADDR_TOP     (VSYSCALL_END-PAGE_SIZE)
  57 #define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  58 #define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)
  59
  60 /* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
  61 #define FIXADDR_USER_START      ((unsigned long)VSYSCALL32_VSYSCALL)
  62 #define FIXADDR_USER_END        (FIXADDR_USER_START + PAGE_SIZE)
  63
  64 #define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  65
  66 extern void __this_fixmap_does_not_exist(void);
  67
  68 /*
  69  * 'index to address' translation. If anyone tries to use the idx
  70  * directly without translation, we catch the bug with a NULL-deference
  71  * kernel oops. Illegal ranges of incoming indices are caught too.
  72  */
  73 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
  74 {
  75         /*
  76          * this branch gets completely eliminated after inlining,
  77          * except when someone tries to use fixaddr indices in an
  78          * illegal way. (such as mixing up address types or using
  79          * out-of-range indices).
  80          *
  81          * If it doesn't get removed, the linker will complain
  82          * loudly with a reasonably clear error message..
  83          */
  84         if (idx >= __end_of_fixed_addresses)
  85                 __this_fixmap_does_not_exist();
  86
  87         return __fix_to_virt(idx);
  88 }
  89
  90 #endif