IntelFspPkg/Library/BaseFspSwitchStackLib/Ia32/Stack.s

   1 #------------------------------------------------------------------------------
   2 #
   3 # Copyright (c) 2014 - 2015, 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
  19 #------------------------------------------------------------------------------
  20 # UINT32
  21 # EFIAPI
  22 # Pei2LoaderSwitchStack (
  23 #   VOID
  24 #   )
  25 #------------------------------------------------------------------------------
  26 ASM_GLOBAL ASM_PFX(Pei2LoaderSwitchStack)
  27 ASM_PFX(Pei2LoaderSwitchStack):
  28     xorl    %eax, %eax
  29     jmp     ASM_PFX(FspSwitchStack)
  30
  31 #------------------------------------------------------------------------------
  32 # UINT32
  33 # EFIAPI
  34 # Loader2PeiSwitchStack (
  35 #   VOID
  36 #   )
  37 #------------------------------------------------------------------------------
  38 ASM_GLOBAL ASM_PFX(Loader2PeiSwitchStack)
  39 ASM_PFX(Loader2PeiSwitchStack):
  40     jmp     ASM_PFX(FspSwitchStack)
  41
  42 #------------------------------------------------------------------------------
  43 # UINT32
  44 # EFIAPI
  45 # FspSwitchStack (
  46 #   VOID
  47 #   )
  48 #------------------------------------------------------------------------------
  49 ASM_GLOBAL ASM_PFX(FspSwitchStack)
  50 ASM_PFX(FspSwitchStack):
  51     #
  52     #Save current contexts
  53     #
  54     push    %eax
  55     pushf
  56     cli
  57     pusha
  58     sub     $0x08, %esp
  59     sidt    (%esp)
  60
  61     #
  62     # Load new stack
  63     #
  64     push   %esp
  65     call   ASM_PFX(SwapStack)
  66     movl   %eax, %esp
  67
  68     #
  69     # Restore previous contexts
  70     #
  71     lidt    (%esp)
  72     add     $0x08,%esp
  73     popa
  74     popf
  75     add     $0x04,%esp
  76     ret
  77
  78