Vlv2TbltDevicePkg/FspSupport/Library/SecFspPlatformSecLibVlv2/Ia32/Stack.asm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2014, 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     .586p
  19     .model  flat,C
  20     .code
  21
  22 ;------------------------------------------------------------------------------
  23 ; VOID
  24 ; EFIAPI
  25 ; SecSwitchStack (
  26 ;   UINT32   TemporaryMemoryBase,
  27 ;   UINT32   PermenentMemoryBase
  28 ;   );
  29 ;------------------------------------------------------------------------------
  30 SecSwitchStack   PROC
  31     ;
  32     ; Save three register: eax, ebx, ecx
  33     ;
  34     push  eax
  35     push  ebx
  36     push  ecx
  37     push  edx
  38
  39     ;
  40     ; !!CAUTION!! this function address's is pushed into stack after
  41     ; migration of whole temporary memory, so need save it to permenent
  42     ; memory at first!
  43     ;
  44
  45     mov   ebx, [esp + 20]          ; Save the first parameter
  46     mov   ecx, [esp + 24]          ; Save the second parameter
  47
  48     ;
  49     ; Save this function's return address into permenent memory at first.
  50     ; Then, Fixup the esp point to permenent memory
  51     ;
  52     mov   eax, esp
  53     sub   eax, ebx
  54     add   eax, ecx
  55     mov   edx, dword ptr [esp]         ; copy pushed register's value to permenent memory
  56     mov   dword ptr [eax], edx
  57     mov   edx, dword ptr [esp + 4]
  58     mov   dword ptr [eax + 4], edx
  59     mov   edx, dword ptr [esp + 8]
  60     mov   dword ptr [eax + 8], edx
  61     mov   edx, dword ptr [esp + 12]
  62     mov   dword ptr [eax + 12], edx
  63     mov   edx, dword ptr [esp + 16]    ; Update this function's return address into permenent memory
  64     mov   dword ptr [eax + 16], edx
  65     mov   esp, eax                     ; From now, esp is pointed to permenent memory
  66
  67     ;
  68     ; Fixup the ebp point to permenent memory
  69     ;
  70     mov   eax, ebp
  71     sub   eax, ebx
  72     add   eax, ecx
  73     mov   ebp, eax                ; From now, ebp is pointed to permenent memory
  74
  75     pop   edx
  76     pop   ecx
  77     pop   ebx
  78     pop   eax
  79     ret
  80 SecSwitchStack   ENDP
  81
  82     END