MdeModulePkg/Universal/EbcDxe/x64/EbcLowLevel.S

   1 ##/**@file
   2 # This code provides low level routines that support the Virtual Machine
   3 # for option ROMs.
   4 #
   5 # Copyright (c) 2007 - 2008, 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 #---------------------------------------------------------------------------
  17 # Equate files needed.
  18 #---------------------------------------------------------------------------
  19
  20 #---------------------------------------------------------------------------
  21 ##GenericPostSegment      SEGMENT USE16
  22 #---------------------------------------------------------------------------
  23
  24 #****************************************************************************
  25 # EbcLLCALLEX
  26 #
  27 # This function is called to execute an EBC CALLEX instruction.
  28 # This instruction requires that we thunk out to external native
  29 # code. For x64, we switch stacks, copy the arguments to the stack
  30 # and jump to the specified function.
  31 # On return, we restore the stack pointer to its original location.
  32 #
  33 # Destroys no working registers.
  34 #****************************************************************************
  35 .global _CopyMem;
  36
  37 # VOID EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr)
  38 .global _EbcLLCALLEXNative;
  39 _EbcLLCALLEXNative:
  40       push   %rbp
  41       push   %rbx
  42       mov    %rsp, %rbp
  43       # Function prolog
  44
  45       # Copy FuncAddr to a preserved register.
  46       mov    %rcx, %rbx
  47
  48       # Set stack pointer to new value
  49       sub    %r8,  %rdx
  50       sub    %rsp, %r8
  51       mov    %rsp, %rcx
  52       sub    %rsp, 0x20
  53       call   _CopyMem
  54       add    %rsp, 0x20
  55
  56       # Considering the worst case, load 4 potiential arguments
  57       # into registers.
  58       mov    (%rsp), %rcx
  59       mov    8(%rsp), %rdx
  60       mov    10(%rsp), %r8
  61       mov    18(%rsp), %r9
  62
  63       # Now call the external routine
  64       call  *%rbx
  65
  66       # Function epilog
  67       mov      %rbp, %rsp
  68       pop      %rbx
  69       pop      %rbp
  70       ret
  71
  72
  73 # UINTN EbcLLGetEbcEntryPoint(VOID);
  74 # Routine Description:
  75 #   The VM thunk code stuffs an EBC entry point into a processor
  76 #   register. Since we can't use inline assembly to get it from
  77 #   the interpreter C code, stuff it into the return value
  78 #   register and return.
  79 #
  80 # Arguments:
  81 #     None.
  82 #
  83 # Returns:
  84 #     The contents of the register in which the entry point is passed.
  85 #
  86 .global _EbcLLGetEbcEntryPoint;
  87 _EbcLLGetEbcEntryPoint:
  88     ret
  89
  90 #/*++
  91 #
  92 #Routine Description:
  93 #
  94 #  Return the caller's value of the stack pointer.
  95 #
  96 #Arguments:
  97 #
  98 #  None.
  99 #
 100 #Returns:
 101 #
 102 #  The current value of the stack pointer for the caller. We
 103 #  adjust it by 4 here because when they called us, the return address
 104 #  is put on the stack, thereby lowering it by 4 bytes.
 105 #
 106 #--*/
 107
 108 # UINTN EbcLLGetStackPointer()
 109 .global _EbcLLGetStackPointer;
 110 _EbcLLGetStackPointer:
 111     mov    %rsp, %rax
 112     # Stack adjusted by this much when we were called,
 113     # For this function, it's 4.
 114     add   $4, %rax
 115     ret
 116
 117 .global _EbcLLGetReturnValue;
 118 _EbcLLGetReturnValue:
 119 # UINT64 EbcLLGetReturnValue(VOID);
 120 # Routine Description:
 121 #   When EBC calls native, on return the VM has to stuff the return
 122 #   value into a VM register. It's assumed here that the value is still
 123 #    in the register, so simply return and the caller should get the
 124 #   return result properly.
 125 #
 126 # Arguments:
 127 #     None.
 128 #
 129 # Returns:
 130 #     The unmodified value returned by the native code.
 131 #
 132     ret