IntelFspPkg/FspSecCore/Ia32/Stacks.s

   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 ASM_GLOBAL ASM_PFX(SecSwitchStack)
  19
  20 #------------------------------------------------------------------------------
  21 # VOID
  22 # EFIAPI
  23 # SecSwitchStack (
  24 #   UINT32   TemporaryMemoryBase,
  25 #   UINT32   PermenentMemoryBase
  26 #   )
  27 #------------------------------------------------------------------------------
  28 ASM_GLOBAL ASM_PFX(SecSwitchStack)
  29 ASM_PFX(SecSwitchStack):
  30 #
  31 # Save three register: eax, ebx, ecx
  32 #
  33     push  %eax
  34     push  %ebx
  35     push  %ecx
  36     push  %edx
  37
  38 #
  39 # !!CAUTION!! this function address's is pushed into stack after
  40 # migration of whole temporary memory, so need save it to permenent
  41 # memory at first!
  42 #
  43
  44     movl  20(%esp), %ebx            # Save the first parameter
  45     movl  24(%esp), %ecx            # Save the second parameter
  46
  47 #
  48 # Save this function's return address into permenent memory at first.
  49 # Then, Fixup the esp point to permenent memory
  50 #
  51
  52     movl  %esp, %eax
  53     subl  %ebx, %eax
  54     addl  %ecx, %eax
  55     movl  (%esp), %edx                 # copy pushed register's value to permenent memory
  56     movl  %edx, (%eax)
  57     movl  4(%esp), %edx
  58     movl  %edx, 4(%eax)
  59     movl  8(%esp), %edx
  60     movl  %edx, 8(%eax)
  61     movl  12(%esp), %edx
  62     movl  %edx, 12(%eax)
  63     movl  16(%esp), %edx               # Update this function's return address into permenent memory
  64     movl  %edx, 16(%eax)
  65     movl  %eax, %esp                   # From now, esp is pointed to permenent memory
  66
  67 #
  68 # Fixup the ebp point to permenent memory
  69 #
  70
  71     movl   %ebp, %eax
  72     subl   %ebx, %eax
  73     addl   %ecx, %eax
  74     movl   %eax, %ebp                  # From now, ebp is pointed to permenent memory
  75
  76 #
  77 # Fixup callee's ebp point for PeiDispatch
  78 #
  79     movl   %ebp, %eax
  80     subl   %ebx, %eax
  81     addl   %ecx, %eax
  82     movl   %eax, %ebp                #  From now, ebp is pointed to permenent memory
  83
  84     pop   %edx
  85     pop   %ecx
  86     pop   %ebx
  87     pop   %eax
  88     ret