MdeModulePkg/Universal/EbcDxe/x64/EbcLowLevel.asm

   1 ;/** @file
   2 ;
   3 ;    This code provides low level routines that support the Virtual Machine.
   4 ;    for option ROMs.
   5 ;
   6 ;  Copyright (c) 2006 - 2008, Intel Corporation. <BR>
   7 ;  All rights reserved. This program and the accompanying materials
   8 ;  are licensed and made available under the terms and conditions of the BSD License
   9 ;  which accompanies this distribution.  The full text of the license may be found at
  10 ;  http://opensource.org/licenses/bsd-license.php
  11 ;
  12 ;  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  13 ;  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  14 ;
  15 ;**/
  16
  17   page    ,132
  18   title   VM ASSEMBLY LANGUAGE ROUTINES
  19
  20 ;---------------------------------------------------------------------------
  21 ; Equate files needed.
  22 ;---------------------------------------------------------------------------
  23
  24 text SEGMENT
  25
  26 ;---------------------------------------------------------------------------
  27 ;;GenericPostSegment      SEGMENT USE16
  28 ;---------------------------------------------------------------------------
  29
  30 ;****************************************************************************
  31 ; EbcLLCALLEX
  32 ;
  33 ; This function is called to execute an EBC CALLEX instruction.
  34 ; This instruction requires that we thunk out to external native
  35 ; code. For x64, we switch stacks, copy the arguments to the stack
  36 ; and jump to the specified function.
  37 ; On return, we restore the stack pointer to its original location.
  38 ;
  39 ; Destroys no working registers.
  40 ;****************************************************************************
  41 ; VOID EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr)
  42
  43 CopyMem  PROTO  Destination:PTR DWORD, Source:PTR DWORD, Count:DWORD
  44
  45
  46 EbcLLCALLEXNative        PROC    PUBLIC
  47       push   rbp
  48       push   rbx
  49       mov    rbp, rsp
  50       ; Function prolog
  51
  52       ; Copy FuncAddr to a preserved register.
  53       mov    rbx, rcx
  54
  55       ; Set stack pointer to new value
  56       sub    r8,  rdx
  57       sub    rsp, r8
  58       mov    rcx, rsp
  59       sub    rsp, 20h
  60       call   CopyMem
  61       add    rsp, 20h
  62
  63       ; Considering the worst case, load 4 potiential arguments
  64       ; into registers.
  65       mov    rcx, qword ptr [rsp]
  66       mov    rdx, qword ptr [rsp+8h]
  67       mov    r8,  qword ptr [rsp+10h]
  68       mov    r9,  qword ptr [rsp+18h]
  69
  70       ; Now call the external routine
  71       call  rbx
  72
  73       ; Function epilog
  74       mov      rsp, rbp
  75       pop      rbx
  76       pop      rbp
  77       ret
  78 EbcLLCALLEXNative    ENDP
  79
  80
  81 ; UINTN EbcLLGetEbcEntryPoint(VOID);
  82 ; Routine Description:
  83 ;   The VM thunk code stuffs an EBC entry point into a processor
  84 ;   register. Since we can't use inline assembly to get it from
  85 ;   the interpreter C code, stuff it into the return value
  86 ;   register and return.
  87 ;
  88 ; Arguments:
  89 ;     None.
  90 ;
  91 ; Returns:
  92 ;     The contents of the register in which the entry point is passed.
  93 ;
  94 EbcLLGetEbcEntryPoint        PROC    PUBLIC
  95     ret
  96 EbcLLGetEbcEntryPoint    ENDP
  97
  98 ;/*++
  99 ;
 100 ;Routine Description:
 101 ;
 102 ;  Return the caller's value of the stack pointer.
 103 ;
 104 ;Arguments:
 105 ;
 106 ;  None.
 107 ;
 108 ;Returns:
 109 ;
 110 ;  The current value of the stack pointer for the caller. We
 111 ;  adjust it by 4 here because when they called us, the return address
 112 ;  is put on the stack, thereby lowering it by 4 bytes.
 113 ;
 114 ;--*/
 115
 116 ; UINTN EbcLLGetStackPointer()
 117 EbcLLGetStackPointer        PROC    PUBLIC
 118     mov    rax, rsp      ; get current stack pointer
 119     ; Stack adjusted by this much when we were called,
 120     ; For this function, it's 4.
 121     add   rax, 4
 122     ret
 123 EbcLLGetStackPointer    ENDP
 124
 125 ; UINT64 EbcLLGetReturnValue(VOID);
 126 ; Routine Description:
 127 ;   When EBC calls native, on return the VM has to stuff the return
 128 ;   value into a VM register. It's assumed here that the value is still
 129 ;    in the register, so simply return and the caller should get the
 130 ;   return result properly.
 131 ;
 132 ; Arguments:
 133 ;     None.
 134 ;
 135 ; Returns:
 136 ;     The unmodified value returned by the native code.
 137 ;
 138 EbcLLGetReturnValue   PROC    PUBLIC
 139     ret
 140 EbcLLGetReturnValue    ENDP
 141
 142 text  ENDS
 143 END
 144