MdeModulePkg/Universal/EbcDxe/Ia32/EbcLowLevel.asm

   1   page    ,132
   2   title   VM ASSEMBLY LANGUAGE ROUTINES
   3 ;****************************************************************************
   4 ;*
   5 ;*  Copyright (c) 2006 - 2007, Intel Corporation
   6 ;*  All rights reserved. This program and the accompanying materials
   7 ;*  are licensed and made available under the terms and conditions of the BSD License
   8 ;*  which accompanies this distribution.  The full text of the license may be found at
   9 ;*  http://opensource.org/licenses/bsd-license.php
  10 ;*
  11 ;*  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12 ;*  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 ;*
  14 ;****************************************************************************
  15 ;****************************************************************************
  16 ;                                   REV 1.0
  17 ;****************************************************************************
  18 ;
  19 ; Rev  Date      Description
  20 ; ---  --------  ------------------------------------------------------------
  21 ; 1.0  03/14/01  Initial creation of file.
  22 ;
  23 ;****************************************************************************
  24
  25 ;* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  26 ; This code provides low level routines that support the Virtual Machine
  27 ; for option ROMs.
  28 ;* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
  29
  30 ;---------------------------------------------------------------------------
  31 ; Equate files needed.
  32 ;---------------------------------------------------------------------------
  33
  34 .XLIST
  35
  36 .LIST
  37
  38 ;---------------------------------------------------------------------------
  39 ; Assembler options
  40 ;---------------------------------------------------------------------------
  41
  42 .686p
  43 .model  flat
  44 .code
  45 ;---------------------------------------------------------------------------
  46 ;;GenericPostSegment      SEGMENT USE16
  47 ;---------------------------------------------------------------------------
  48 CopyMem  PROTO  C Destination:PTR DWORD, Source:PTR DWORD, Count:DWORD
  49
  50 ;****************************************************************************
  51 ; EbcLLCALLEXNative
  52 ;
  53 ; This function is called to execute an EBC CALLEX instruction
  54 ; to native code.
  55 ; This instruction requires that we thunk out to external native
  56 ; code. For IA32, we simply switch stacks and jump to the
  57 ; specified function. On return, we restore the stack pointer
  58 ; to its original location.
  59 ;
  60 ; Destroys no working registers.
  61 ;****************************************************************************
  62 ; VOID EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr)
  63 _EbcLLCALLEXNative        PROC    NEAR    PUBLIC
  64       push   ebp
  65       push   ebx
  66       mov    ebp, esp              ; standard function prolog
  67
  68       ; Get function address in a register
  69       ; mov ecx, FuncAddr => mov ecx, dword ptr [FuncAddr]
  70       mov    ecx, dword ptr [esp]+0Ch
  71
  72       ; Set stack pointer to new value
  73       ; mov eax, NewStackPointer => mov eax, dword ptr [NewSp]
  74       mov    eax, dword ptr [esp] + 14h
  75       mov    edx, dword ptr [esp] + 10h
  76       sub    eax, edx
  77       sub    esp, eax
  78       mov    ebx, esp
  79       push   ecx
  80       push   eax
  81       push   edx
  82       push   ebx
  83       call   CopyMem
  84       pop    eax
  85       pop    eax
  86       pop    eax
  87       pop    ecx
  88
  89       ; Now call the external routine
  90       call  ecx
  91
  92       ; ebp is preserved by the callee. In this function it
  93       ; equals the original esp, so set them equal
  94       mov    esp, ebp
  95
  96       ; Standard function epilog
  97       mov      esp, ebp
  98       pop      ebx
  99       pop      ebp
 100       ret
 101 _EbcLLCALLEXNative    ENDP
 102
 103
 104 ; UINTN EbcLLGetEbcEntryPoint(VOID);
 105 ; Routine Description:
 106 ;   The VM thunk code stuffs an EBC entry point into a processor
 107 ;   register. Since we can't use inline assembly to get it from
 108 ;   the interpreter C code, stuff it into the return value
 109 ;   register and return.
 110 ;
 111 ; Arguments:
 112 ;     None.
 113 ;
 114 ; Returns:
 115 ;     The contents of the register in which the entry point is passed.
 116 ;
 117 _EbcLLGetEbcEntryPoint        PROC    NEAR    PUBLIC
 118     ret
 119 _EbcLLGetEbcEntryPoint    ENDP
 120
 121 ;/*++
 122 ;
 123 ;Routine Description:
 124 ;
 125 ;  Return the caller's value of the stack pointer.
 126 ;
 127 ;Arguments:
 128 ;
 129 ;  None.
 130 ;
 131 ;Returns:
 132 ;
 133 ;  The current value of the stack pointer for the caller. We
 134 ;  adjust it by 4 here because when they called us, the return address
 135 ;  is put on the stack, thereby lowering it by 4 bytes.
 136 ;
 137 ;--*/
 138
 139 ; UINTN EbcLLGetStackPointer()
 140 _EbcLLGetStackPointer        PROC    NEAR    PUBLIC
 141     mov    eax, esp      ; get current stack pointer
 142     add   eax, 4        ; stack adjusted by this much when we were called
 143     ret
 144 _EbcLLGetStackPointer    ENDP
 145
 146 ; UINT64 EbcLLGetReturnValue(VOID);
 147 ; Routine Description:
 148 ;   When EBC calls native, on return the VM has to stuff the return
 149 ;   value into a VM register. It's assumed here that the value is still
 150 ;    in the register, so simply return and the caller should get the
 151 ;   return result properly.
 152 ;
 153 ; Arguments:
 154 ;     None.
 155 ;
 156 ; Returns:
 157 ;     The unmodified value returned by the native code.
 158 ;
 159 _EbcLLGetReturnValue   PROC    NEAR    PUBLIC
 160     ret
 161 _EbcLLGetReturnValue    ENDP
 162
 163 END