UefiCpuPkg/PiSmmCpuDxeSmm/X64/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 DEFAULT REL
  16 SECTION .text
  17
  18 global ASM_PFX(DisableCet)
  19 ASM_PFX(DisableCet):
  20
  21     ; Skip the pushed data for call
  22     mov     rax, 1
  23     INCSSP_RAX
  24
  25     mov     rax, cr4
  26     btr     eax, 23                      ; clear CET
  27     mov     cr4, rax
  28     ret
  29
  30 global ASM_PFX(EnableCet)
  31 ASM_PFX(EnableCet):
  32
  33     mov     rax, cr4
  34     bts     eax, 23                      ; set CET
  35     mov     cr4, rax
  36
  37     ; use jmp to skip the check for ret
  38     pop     rax
  39     jmp     rax
  40