EdkModulePkg/Universal/Ebc/Dxe/x64/EbcLowLevel.asm

   1   page    ,132
   2   title   VM ASSEMBLY LANGUAGE ROUTINES
   3 ;****************************************************************************
   4 ;*
   5 ;*  Copyright (c) 2006, 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  05/09/12  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 text SEGMENT
  35
  36 ;---------------------------------------------------------------------------
  37 ;;GenericPostSegment      SEGMENT USE16
  38 ;---------------------------------------------------------------------------
  39
  40 ;****************************************************************************
  41 ; EbcLLCALLEX
  42 ;
  43 ; This function is called to execute an EBC CALLEX instruction.
  44 ; This instruction requires that we thunk out to external native
  45 ; code. For x64, we switch stacks, copy the arguments to the stack
  46 ; and jump to the specified function.
  47 ; On return, we restore the stack pointer to its original location.
  48 ;
  49 ; Destroys no working registers.
  50 ;****************************************************************************
  51 ; VOID EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr)
  52 EbcLLCALLEXNative        PROC
  53       push   rbp
  54       push   rbx
  55       mov    rbp, rsp
  56       ; Function prolog
  57
  58       ; Copy FuncAddr to a preserved register.
  59       mov    rbx, rcx
  60
  61       ; Set stack pointer to new value
  62       mov    rsp, rdx
  63
  64       ; Considering the worst case, load 4 potiential arguments
  65       ; into registers.
  66       mov    rcx, qword ptr [rsp]
  67       mov    rdx, qword ptr [rsp+8h]
  68       mov    r8,  qword ptr [rsp+10h]
  69       mov    r9,  qword ptr [rsp+18h]
  70
  71       ; Now call the external routine
  72       call  rbx
  73
  74       ; Function epilog
  75       mov      rsp, rbp
  76       pop      rbx
  77       pop      rbp
  78       ret
  79 EbcLLCALLEXNative    ENDP
  80
  81
  82 ; UINTN EbcLLGetEbcEntryPoint(VOID);
  83 ; Routine Description:
  84 ;   The VM thunk code stuffs an EBC entry point into a processor
  85 ;   register. Since we can't use inline assembly to get it from
  86 ;   the interpreter C code, stuff it into the return value
  87 ;   register and return.
  88 ;
  89 ; Arguments:
  90 ;     None.
  91 ;
  92 ; Returns:
  93 ;     The contents of the register in which the entry point is passed.
  94 ;
  95 EbcLLGetEbcEntryPoint        PROC
  96     ret
  97 EbcLLGetEbcEntryPoint    ENDP
  98
  99 ;/*++
 100 ;
 101 ;Routine Description:
 102 ;
 103 ;  Return the caller's value of the stack pointer.
 104 ;
 105 ;Arguments:
 106 ;
 107 ;  None.
 108 ;
 109 ;Returns:
 110 ;
 111 ;  The current value of the stack pointer for the caller. We
 112 ;  adjust it by 4 here because when they called us, the return address
 113 ;  is put on the stack, thereby lowering it by 4 bytes.
 114 ;
 115 ;--*/
 116
 117 ; UINTN EbcLLGetStackPointer()
 118 EbcLLGetStackPointer        PROC
 119     mov    rax, rsp      ; get current stack pointer
 120     ; Stack adjusted by this much when we were called,
 121     ; For this function, it's 4.
 122     add   rax, 4
 123     ret
 124 EbcLLGetStackPointer    ENDP
 125
 126 ; UINT64 EbcLLGetReturnValue(VOID);
 127 ; Routine Description:
 128 ;   When EBC calls native, on return the VM has to stuff the return
 129 ;   value into a VM register. It's assumed here that the value is still
 130 ;    in the register, so simply return and the caller should get the
 131 ;   return result properly.
 132 ;
 133 ; Arguments:
 134 ;     None.
 135 ;
 136 ; Returns:
 137 ;     The unmodified value returned by the native code.
 138 ;
 139 EbcLLGetReturnValue   PROC
 140     ret
 141 EbcLLGetReturnValue    ENDP
 142
 143 text  ENDS
 144 END
 145