IntelFspPkg/FspSecCore/Ia32/Stack.asm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2014, Intel Corporation. All rights reserved.<BR>
   4 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   5 ;
   6 ; Abstract:
   7 ;
   8 ;   Switch the stack from temporary memory to permenent memory.
   9 ;
  10 ;------------------------------------------------------------------------------
  11
  12     .586p
  13     .model  flat,C
  14     .code
  15
  16 ;------------------------------------------------------------------------------
  17 ; VOID
  18 ; EFIAPI
  19 ; SecSwitchStack (
  20 ;   UINT32   TemporaryMemoryBase,
  21 ;   UINT32   PermenentMemoryBase
  22 ;   );
  23 ;------------------------------------------------------------------------------
  24 SecSwitchStack   PROC
  25     ;
  26     ; Save three register: eax, ebx, ecx
  27     ;
  28     push  eax
  29     push  ebx
  30     push  ecx
  31     push  edx
  32
  33     ;
  34     ; !!CAUTION!! this function address's is pushed into stack after
  35     ; migration of whole temporary memory, so need save it to permenent
  36     ; memory at first!
  37     ;
  38
  39     mov   ebx, [esp + 20]          ; Save the first parameter
  40     mov   ecx, [esp + 24]          ; Save the second parameter
  41
  42     ;
  43     ; Save this function's return address into permenent memory at first.
  44     ; Then, Fixup the esp point to permenent memory
  45     ;
  46     mov   eax, esp
  47     sub   eax, ebx
  48     add   eax, ecx
  49     mov   edx, dword ptr [esp]         ; copy pushed register's value to permenent memory
  50     mov   dword ptr [eax], edx
  51     mov   edx, dword ptr [esp + 4]
  52     mov   dword ptr [eax + 4], edx
  53     mov   edx, dword ptr [esp + 8]
  54     mov   dword ptr [eax + 8], edx
  55     mov   edx, dword ptr [esp + 12]
  56     mov   dword ptr [eax + 12], edx
  57     mov   edx, dword ptr [esp + 16]    ; Update this function's return address into permenent memory
  58     mov   dword ptr [eax + 16], edx
  59     mov   esp, eax                     ; From now, esp is pointed to permenent memory
  60
  61     ;
  62     ; Fixup the ebp point to permenent memory
  63     ;
  64     mov   eax, ebp
  65     sub   eax, ebx
  66     add   eax, ecx
  67     mov   ebp, eax                ; From now, ebp is pointed to permenent memory
  68
  69     pop   edx
  70     pop   ecx
  71     pop   ebx
  72     pop   eax
  73     ret
  74 SecSwitchStack   ENDP
  75
  76     END