MdePkg/Library/BaseLib/Ia32/WriteDr5.asm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2006, Intel Corporation
   4 ; All rights reserved. This program and the accompanying materials
   5 ; are licensed and made available under the terms and conditions of the BSD License
   6 ; which accompanies this distribution.  The full text of the license may be found at
   7 ; http://opensource.org/licenses/bsd-license.php
   8 ;
   9 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 ;
  12 ; Module Name:
  13 ;
  14 ;   WriteDr5.Asm
  15 ;
  16 ; Abstract:
  17 ;
  18 ;   AsmWriteDr5 function
  19 ;
  20 ; Notes:
  21 ;
  22 ;------------------------------------------------------------------------------
  23
  24     .586p
  25     .model  flat,C
  26     .code
  27
  28 ;------------------------------------------------------------------------------
  29 ; UINTN
  30 ; EFIAPI
  31 ; AsmWriteDr5 (
  32 ;   IN UINTN Value
  33 ;   );
  34 ;------------------------------------------------------------------------------
  35 AsmWriteDr5 PROC
  36     mov     eax, [esp + 4]
  37     ;
  38     ; DR5 is alias to DR7 only if DE (in CR4) is cleared. Otherwise, writing to
  39     ; this register will cause a #UD exception.
  40     ;
  41     ; MS assembler doesn't support this instruction since no one would use it
  42     ; under normal circustances. Here opcode is used.
  43     ;
  44     DB      0fh, 23h, 0e8h
  45     ret
  46 AsmWriteDr5 ENDP
  47
  48     END