page ,132 title VM ASSEMBLY LANGUAGE ROUTINES ;**************************************************************************** ;* ;* Copyright (c) 2006 - 2007, Intel Corporation ;* All rights reserved. This program and the accompanying materials ;* are licensed and made available under the terms and conditions of the BSD License ;* which accompanies this distribution. The full text of the license may be found at ;* http://opensource.org/licenses/bsd-license.php ;* ;* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, ;* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. ;* ;**************************************************************************** ;**************************************************************************** ; REV 1.0 ;**************************************************************************** ; ; Rev Date Description ; --- -------- ------------------------------------------------------------ ; 1.0 03/14/01 Initial creation of file. ; ;**************************************************************************** ;* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ; This code provides low level routines that support the Virtual Machine ; for option ROMs. ;* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ;--------------------------------------------------------------------------- ; Equate files needed. ;--------------------------------------------------------------------------- .XLIST .LIST ;--------------------------------------------------------------------------- ; Assembler options ;--------------------------------------------------------------------------- .686p .model flat .code ;--------------------------------------------------------------------------- ;;GenericPostSegment SEGMENT USE16 ;--------------------------------------------------------------------------- CopyMem PROTO C Destination:PTR DWORD, Source:PTR DWORD, Count:DWORD ;**************************************************************************** ; EbcLLCALLEXNative ; ; This function is called to execute an EBC CALLEX instruction ; to native code. ; This instruction requires that we thunk out to external native ; code. For IA32, we simply switch stacks and jump to the ; specified function. On return, we restore the stack pointer ; to its original location. ; ; Destroys no working registers. ;**************************************************************************** ; VOID EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr) _EbcLLCALLEXNative PROC NEAR PUBLIC push ebp push ebx mov ebp, esp ; standard function prolog ; Get function address in a register ; mov ecx, FuncAddr => mov ecx, dword ptr [FuncAddr] mov ecx, dword ptr [esp]+0Ch ; Set stack pointer to new value ; mov eax, NewStackPointer => mov eax, dword ptr [NewSp] mov eax, dword ptr [esp] + 14h mov edx, dword ptr [esp] + 10h sub eax, edx sub esp, eax mov ebx, esp push ecx push eax push edx push ebx call CopyMem pop eax pop eax pop eax pop ecx ; Now call the external routine call ecx ; ebp is preserved by the callee. In this function it ; equals the original esp, so set them equal mov esp, ebp ; Standard function epilog mov esp, ebp pop ebx pop ebp ret _EbcLLCALLEXNative ENDP ; UINTN EbcLLGetEbcEntryPoint(VOID); ; Routine Description: ; The VM thunk code stuffs an EBC entry point into a processor ; register. Since we can't use inline assembly to get it from ; the interpreter C code, stuff it into the return value ; register and return. ; ; Arguments: ; None. ; ; Returns: ; The contents of the register in which the entry point is passed. ; _EbcLLGetEbcEntryPoint PROC NEAR PUBLIC ret _EbcLLGetEbcEntryPoint ENDP ;/*++ ; ;Routine Description: ; ; Return the caller's value of the stack pointer. ; ;Arguments: ; ; None. ; ;Returns: ; ; The current value of the stack pointer for the caller. We ; adjust it by 4 here because when they called us, the return address ; is put on the stack, thereby lowering it by 4 bytes. ; ;--*/ ; UINTN EbcLLGetStackPointer() _EbcLLGetStackPointer PROC NEAR PUBLIC mov eax, esp ; get current stack pointer add eax, 4 ; stack adjusted by this much when we were called ret _EbcLLGetStackPointer ENDP ; UINT64 EbcLLGetReturnValue(VOID); ; Routine Description: ; When EBC calls native, on return the VM has to stuff the return ; value into a VM register. It's assumed here that the value is still ; in the register, so simply return and the caller should get the ; return result properly. ; ; Arguments: ; None. ; ; Returns: ; The unmodified value returned by the native code. ; _EbcLLGetReturnValue PROC NEAR PUBLIC ret _EbcLLGetReturnValue ENDP END