UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/Cet.nasm

   1 ;------------------------------------------------------------------------------ ;
   2 ; Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
   3 ; This program and the accompanying materials
   4 ; are licensed and made available under the terms and conditions of the BSD License
   5 ; which accompanies this distribution.  The full text of the license may be found at
   6 ; http://opensource.org/licenses/bsd-license.php.
   7 ;
   8 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
   9 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  10 ;
  11 ;-------------------------------------------------------------------------------
  12
  13 %include "Nasm.inc"
  14
  15 SECTION .text
  16
  17 global ASM_PFX(DisableCet)
  18 ASM_PFX(DisableCet):
  19
  20     ; Skip the pushed data for call
  21     mov     eax, 1
  22     INCSSP_EAX
  23
  24     mov     eax, cr4
  25     btr     eax, 23                      ; clear CET
  26     mov     cr4, eax
  27     ret
  28
  29 global ASM_PFX(EnableCet)
  30 ASM_PFX(EnableCet):
  31
  32     mov     eax, cr4
  33     bts     eax, 23                      ; set CET
  34     mov     cr4, eax
  35
  36     ; use jmp to skip the check for ret
  37     pop     eax
  38     jmp     eax
  39