summaryrefslogtreecommitdiff
path: root/MdePkg/Library/BaseLib/Ia32/ReadDr5.asm
blob: 58b4ac26da763cf9b99749e62b64cff8f6733e88 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
;------------------------------------------------------------------------------
;
; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
; This program and the accompanying materials
; are licensed and made available under the terms and conditions of the BSD License
; which accompanies this distribution.  The full text of the license may be found at
; http://opensource.org/licenses/bsd-license.php.
;
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
;
; Module Name:
;
;   ReadDr5.Asm
;
; Abstract:
;
;   AsmReadDr5 function
;
; Notes:
;
;------------------------------------------------------------------------------

    .586p
    .model  flat,C
    .code

;------------------------------------------------------------------------------
; UINTN
; EFIAPI
; AsmReadDr5 (
;   VOID
;   );
;------------------------------------------------------------------------------
AsmReadDr5  PROC
    ;
    ; DR5 is alias to DR7 only if DE (in CR4) is cleared. Otherwise, reading
    ; this register will cause a #UD exception.
    ;
    ; MS assembler doesn't support this instruction since no one would use it
    ; under normal circustances. Here opcode is used.
    ;
    DB      0fh, 21h, 0e8h
    ret
AsmReadDr5  ENDP

    END