IntelFsp2Pkg/Library/BaseFspSwitchStackLib/Ia32/Stack.nasm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
   4 ; This program and the accompanying materials
   5 ; are licensed and made available under the terms and conditions of the BSD License
   6 ; which accompanies this distribution.  The full text of the license may be found at
   7 ; http://opensource.org/licenses/bsd-license.php.
   8 ;
   9 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 ;
  12 ; Abstract:
  13 ;
  14 ;   Switch the stack from temporary memory to permenent memory.
  15 ;
  16 ;------------------------------------------------------------------------------
  17
  18     SECTION .text
  19
  20 extern ASM_PFX(SwapStack)
  21
  22 ;------------------------------------------------------------------------------
  23 ; UINT32
  24 ; EFIAPI
  25 ; Pei2LoaderSwitchStack (
  26 ;   VOID
  27 ;   )
  28 ;------------------------------------------------------------------------------
  29 global ASM_PFX(Pei2LoaderSwitchStack)
  30 ASM_PFX(Pei2LoaderSwitchStack):
  31     xor     eax, eax
  32     jmp     ASM_PFX(FspSwitchStack)
  33
  34 ;------------------------------------------------------------------------------
  35 ; UINT32
  36 ; EFIAPI
  37 ; Loader2PeiSwitchStack (
  38 ;   VOID
  39 ;   )
  40 ;------------------------------------------------------------------------------
  41 global ASM_PFX(Loader2PeiSwitchStack)
  42 ASM_PFX(Loader2PeiSwitchStack):
  43     jmp     ASM_PFX(FspSwitchStack)
  44
  45 ;------------------------------------------------------------------------------
  46 ; UINT32
  47 ; EFIAPI
  48 ; FspSwitchStack (
  49 ;   VOID
  50 ;   )
  51 ;------------------------------------------------------------------------------
  52 global ASM_PFX(FspSwitchStack)
  53 ASM_PFX(FspSwitchStack):
  54     ; Save current contexts
  55     push    eax
  56     pushfd
  57     cli
  58     pushad
  59     sub     esp, 8
  60     sidt    [esp]
  61
  62     ; Load new stack
  63     push    esp
  64     call    ASM_PFX(SwapStack)
  65     mov     esp, eax
  66
  67     ; Restore previous contexts
  68     lidt    [esp]
  69     add     esp, 8
  70     popad
  71     popfd
  72     add     esp, 4
  73     ret
  74