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 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   6 ;
   7 ; Module Name:
   8 ;
   9 ;   InternalSwitchStack.nasm
  10 ;
  11 ; Abstract:
  12 ;
  13 ;   Implementation of a stack switch on IA-32.
  14 ;
  15 ;------------------------------------------------------------------------------
  16
  17     SECTION .text
  18
  19 ;------------------------------------------------------------------------------
  20 ; VOID
  21 ; EFIAPI
  22 ; InternalSwitchStack (
  23 ;   IN      SWITCH_STACK_ENTRY_POINT  EntryPoint,
  24 ;   IN      VOID                      *Context1,   OPTIONAL
  25 ;   IN      VOID                      *Context2,   OPTIONAL
  26 ;   IN      VOID                      *NewStack
  27 ;   );
  28 ;------------------------------------------------------------------------------
  29 global ASM_PFX(InternalSwitchStack)
  30 ASM_PFX(InternalSwitchStack):
  31   push  ebp
  32   mov   ebp, esp
  33
  34   mov   esp, [ebp + 20]    ; switch stack
  35   sub   esp, 8
  36   mov   eax, [ebp + 16]
  37   mov   [esp + 4], eax
  38   mov   eax, [ebp + 12]
  39   mov   [esp], eax
  40   push  0                  ; keeps gdb from unwinding stack
  41   jmp   dword [ebp + 8]    ; call and never return