UefiCpuPkg/PiSmmCpuDxeSmm/X64/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 DEFAULT REL
  10 SECTION .text
  11
  12 global ASM_PFX(DisableCet)
  13 ASM_PFX(DisableCet):
  14
  15     ; Skip the pushed data for call
  16     mov     rax, 1
  17     INCSSP_RAX
  18
  19     mov     rax, cr4
  20     btr     eax, 23                      ; clear CET
  21     mov     cr4, rax
  22     ret
  23
  24 global ASM_PFX(EnableCet)
  25 ASM_PFX(EnableCet):
  26
  27     mov     rax, cr4
  28     bts     eax, 23                      ; set CET
  29     mov     cr4, rax
  30
  31     ; use jmp to skip the check for ret
  32     pop     rax
  33     jmp     rax
  34