UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/Cet.nasm

   1 ;------------------------------------------------------------------------------ ;
   2 ; Copyright (c) 2019, Intel Corporation. All rights reserved.<BR>
   3 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   4 ;
   5 ;-------------------------------------------------------------------------------
   6
   7 %include "Nasm.inc"
   8
   9 SECTION .text
  10
  11 global ASM_PFX(DisableCet)
  12 ASM_PFX(DisableCet):
  13
  14     ; Skip the pushed data for call
  15     mov     eax, 1
  16     INCSSP_EAX
  17
  18     mov     eax, cr4
  19     btr     eax, 23                      ; clear CET
  20     mov     cr4, eax
  21     ret
  22
  23 global ASM_PFX(EnableCet)
  24 ASM_PFX(EnableCet):
  25
  26     mov     eax, cr4
  27     bts     eax, 23                      ; set CET
  28     mov     cr4, eax
  29
  30     ; use jmp to skip the check for ret
  31     pop     eax
  32     jmp     eax
  33