mirror of https://github.com/acidanthera/audk.git
146 lines
5.0 KiB
NASM
146 lines
5.0 KiB
NASM
page ,132
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title VM ASSEMBLY LANGUAGE ROUTINES
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;****************************************************************************
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;*
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;* Copyright (c) 2006, Intel Corporation
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;* All rights reserved. This program and the accompanying materials
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;* are licensed and made available under the terms and conditions of the BSD License
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;* which accompanies this distribution. The full text of the license may be found at
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;* http://opensource.org/licenses/bsd-license.php
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;*
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;* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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;* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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;*
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;****************************************************************************
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;****************************************************************************
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; REV 1.0
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;****************************************************************************
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;
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; Rev Date Description
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; --- -------- ------------------------------------------------------------
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; 1.0 05/09/12 Initial creation of file.
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;
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;****************************************************************************
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;* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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; This code provides low level routines that support the Virtual Machine
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; for option ROMs.
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;* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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;---------------------------------------------------------------------------
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; Equate files needed.
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;---------------------------------------------------------------------------
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text SEGMENT
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;---------------------------------------------------------------------------
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;;GenericPostSegment SEGMENT USE16
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;---------------------------------------------------------------------------
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;****************************************************************************
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; EbcLLCALLEX
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;
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; This function is called to execute an EBC CALLEX instruction.
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; This instruction requires that we thunk out to external native
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; code. For x64, we switch stacks, copy the arguments to the stack
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; and jump to the specified function.
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; On return, we restore the stack pointer to its original location.
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;
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; Destroys no working registers.
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;****************************************************************************
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; VOID EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr)
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EbcLLCALLEXNative PROC
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push rbp
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push rbx
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mov rbp, rsp
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; Function prolog
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; Copy FuncAddr to a preserved register.
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mov rbx, rcx
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; Set stack pointer to new value
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mov rsp, rdx
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; Considering the worst case, load 4 potiential arguments
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; into registers.
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mov rcx, qword ptr [rsp]
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mov rdx, qword ptr [rsp+8h]
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mov r8, qword ptr [rsp+10h]
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mov r9, qword ptr [rsp+18h]
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; Now call the external routine
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call rbx
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; Function epilog
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mov rsp, rbp
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pop rbx
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pop rbp
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ret
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EbcLLCALLEXNative ENDP
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; UINTN EbcLLGetEbcEntryPoint(VOID);
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; Routine Description:
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; The VM thunk code stuffs an EBC entry point into a processor
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; register. Since we can't use inline assembly to get it from
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; the interpreter C code, stuff it into the return value
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; register and return.
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;
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; Arguments:
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; None.
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;
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; Returns:
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; The contents of the register in which the entry point is passed.
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;
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EbcLLGetEbcEntryPoint PROC
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ret
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EbcLLGetEbcEntryPoint ENDP
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;/*++
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;
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;Routine Description:
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;
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; Return the caller's value of the stack pointer.
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;
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;Arguments:
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;
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; None.
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;
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;Returns:
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;
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; The current value of the stack pointer for the caller. We
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; adjust it by 4 here because when they called us, the return address
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; is put on the stack, thereby lowering it by 4 bytes.
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;
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;--*/
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; UINTN EbcLLGetStackPointer()
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EbcLLGetStackPointer PROC
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mov rax, rsp ; get current stack pointer
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; Stack adjusted by this much when we were called,
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; For this function, it's 4.
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add rax, 4
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ret
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EbcLLGetStackPointer ENDP
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; UINT64 EbcLLGetReturnValue(VOID);
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; Routine Description:
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; When EBC calls native, on return the VM has to stuff the return
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; value into a VM register. It's assumed here that the value is still
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; in the register, so simply return and the caller should get the
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; return result properly.
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;
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; Arguments:
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; None.
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;
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; Returns:
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; The unmodified value returned by the native code.
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;
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EbcLLGetReturnValue PROC
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ret
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EbcLLGetReturnValue ENDP
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text ENDS
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END
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