MdePkg/Library/BaseLib/Ia32/InternalSwitchStack.S

   1 #------------------------------------------------------------------------------
   2 #
   3 # Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
   4 # Portions copyright (c) 2011, Apple Inc. All rights reserved.<BR>
   5 # This program and the accompanying materials
   6 # are licensed and made available under the terms and conditions of the BSD License
   7 # which accompanies this distribution.  The full text of the license may be found at
   8 # http://opensource.org/licenses/bsd-license.php.
   9 #
  10 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12 #
  13 # Module Name:
  14 #
  15 #   InternalSwitchStack.S
  16 #
  17 # Abstract:
  18 #
  19 #   Implementation of a stack switch on IA-32.
  20 #
  21 #------------------------------------------------------------------------------
  22
  23 ASM_GLOBAL ASM_PFX(InternalSwitchStack)
  24
  25 #------------------------------------------------------------------------------
  26 # VOID
  27 # EFIAPI
  28 # InternalSwitchStack (
  29 #   IN      SWITCH_STACK_ENTRY_POINT  EntryPoint,
  30 #   IN      VOID                      *Context1,   OPTIONAL
  31 #   IN      VOID                      *Context2,   OPTIONAL
  32 #   IN      VOID                      *NewStack
  33 #   );
  34 #------------------------------------------------------------------------------
  35 ASM_PFX(InternalSwitchStack):
  36   pushl %ebp
  37         movl    %esp, %ebp
  38
  39         movl    20(%ebp), %esp      # switch stack
  40         subl    $8, %esp
  41
  42         movl    16(%ebp), %eax
  43         movl    %eax, 4(%esp)
  44         movl    12(%ebp), %eax
  45         movl    %eax, (%esp)
  46         pushl $0                  # keeps gdb from unwinding stack
  47         jmp   *8(%ebp)            # call and never return
  48