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_DBGP_BASE,
  39         FIX_EARLYCON_MEM_BASE,
  40         FIX_HPET_BASE,
  41         FIX_APIC_BASE,  /* local (CPU) APIC) -- required for SMP or not */
  42         FIX_IO_APIC_BASE_0,
  43         FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
  44         __end_of_fixed_addresses
  45 };
  46
  47 extern void __set_fixmap (enum fixed_addresses idx,
  48                                         unsigned long phys, pgprot_t flags);
  49
  50 #define set_fixmap(idx, phys) \
  51                 __set_fixmap(idx, phys, PAGE_KERNEL)
  52 /*
  53  * Some hardware wants to get fixmapped without caching.
  54  */
  55 #define set_fixmap_nocache(idx, phys) \
  56                 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
  57
  58 #define FIXADDR_TOP     (VSYSCALL_END-PAGE_SIZE)
  59 #define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)
  60 #define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)
  61
  62 /* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
  63 #define FIXADDR_USER_START      ((unsigned long)VSYSCALL32_VSYSCALL)
  64 #define FIXADDR_USER_END        (FIXADDR_USER_START + PAGE_SIZE)
  65
  66 #define __fix_to_virt(x)        (FIXADDR_TOP - ((x) << PAGE_SHIFT))
  67
  68 extern void __this_fixmap_does_not_exist(void);
  69
  70 /*
  71  * 'index to address' translation. If anyone tries to use the idx
  72  * directly without translation, we catch the bug with a NULL-deference
  73  * kernel oops. Illegal ranges of incoming indices are caught too.
  74  */
  75 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
  76 {
  77         /*
  78          * this branch gets completely eliminated after inlining,
  79          * except when someone tries to use fixaddr indices in an
  80          * illegal way. (such as mixing up address types or using
  81          * out-of-range indices).
  82          *
  83          * If it doesn't get removed, the linker will complain
  84          * loudly with a reasonably clear error message..
  85          */
  86         if (idx >= __end_of_fixed_addresses)
  87                 __this_fixmap_does_not_exist();
  88
  89         return __fix_to_virt(idx);
  90 }
  91
  92 #endif