MdePkg/Library/BaseLib/Ia32/InternalSwitchStack.nasm

   1 ;------------------------------------------------------------------------------
   2 ;
   3 ; Copyright (c) 2016, 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.nasm
  16 ;
  17 ; Abstract:
  18 ;
  19 ;   Implementation of a stack switch on IA-32.
  20 ;
  21 ;------------------------------------------------------------------------------
  22
  23     SECTION .text
  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 global ASM_PFX(InternalSwitchStack)
  36 ASM_PFX(InternalSwitchStack):
  37   push  ebp
  38   mov   ebp, esp
  39
  40   mov   esp, [ebp + 20]    ; switch stack
  41   sub   esp, 8
  42   mov   eax, [ebp + 16]
  43   mov   [esp + 4], eax
  44   mov   eax, [ebp + 12]
  45   mov   [esp], eax
  46   push  0                  ; keeps gdb from unwinding stack
  47   jmp   dword [ebp + 8]    ; call and never return