EmulatorPkg/Sec/Ia32/SwitchRam.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # Copyright (c) 2007, 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 # Module Name:
  13 #
  14 #   Stack.asm
  15 #
  16 # Abstract:
  17 #
  18 #   Switch the stack from temporary memory to permenent memory.
  19 #
  20 #------------------------------------------------------------------------------
  21
  22  .text
  23
  24
  25 //------------------------------------------------------------------------------
  26 // VOID
  27 // EFIAPI
  28 // SecSwitchStack (
  29 //   UINT32   TemporaryMemoryBase,
  30 //   UINT32   PermenentMemoryBase
  31 //   )//
  32 //------------------------------------------------------------------------------
  33 ASM_GLOBAL ASM_PFX(SecSwitchStack)
  34 ASM_PFX(SecSwitchStack):
  35 #
  36 # Save three register: eax, ebx, ecx
  37 #
  38     push  %eax
  39     push  %ebx
  40     push  %ecx
  41     push  %edx
  42
  43 #
  44 # !!CAUTION!! this function address's is pushed into stack after
  45 # migration of whole temporary memory, so need save it to permenent
  46 # memory at first!
  47 #
  48
  49     movl  20(%esp), %ebx            # Save the first parameter
  50     movl  24(%esp), %ecx            # Save the second parameter
  51
  52 #
  53 # Save this function's return address into permenent memory at first.
  54 # Then, Fixup the esp point to permenent memory
  55 #
  56
  57     movl  %esp, %eax
  58     subl  %ebx, %eax
  59     addl  %ecx, %eax
  60     movl  (%esp), %edx                 # copy pushed register's value to permenent memory
  61     movl  %edx, (%eax)
  62     movl  4(%esp), %edx
  63     movl  %edx, 4(%eax)
  64     movl  8(%esp), %edx
  65     movl  %edx, 8(%eax)
  66     movl  12(%esp), %edx
  67     movl  %edx, 12(%eax)
  68     movl  16(%esp), %edx
  69     movl  %edx, 16(%eax)
  70     movl  %eax, %esp                   # From now, esp is pointed to permenent memory
  71
  72 #
  73 # Fixup the ebp point to permenent memory
  74 #
  75 #ifndef __APPLE__
  76     movl   %ebp, %eax
  77     subl   %ebx, %eax
  78     addl   %ecx, %eax
  79     movl   %eax, %ebp                  # From now, ebp is pointed to permenent memory
  80
  81 #
  82 # Fixup callee's ebp point for PeiDispatch
  83 #
  84     movl   (%ebp), %eax
  85     subl   %ebx, %eax
  86     addl   %ecx, %eax
  87     movl   %eax, (%ebp)                # From now, Temporary's PPI caller's stack is in permenent memory
  88 #endif
  89
  90     pop   %edx
  91     pop   %ecx
  92     pop   %ebx
  93     pop   %eax
  94     ret
  95