;/** @file

;

; This code provides low level routines that support the Virtual Machine.

; for option ROMs.

;

; Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>

; 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.

;

;**/

page ,132

title VM ASSEMBLY LANGUAGE ROUTINES

;---------------------------------------------------------------------------

; Equate files needed.

;---------------------------------------------------------------------------

.CODE

CopyMem PROTO Destination:PTR DWORD, Source:PTR DWORD, Count:DWORD

EbcInterpret PROTO

ExecuteEbcImageEntryPoint PROTO

;****************************************************************************

; EbcLLCALLEX

;

; This function is called to execute an EBC CALLEX instruction.

; This instruction requires that we thunk out to external native

; code. For x64, we switch stacks, copy the arguments to the stack

; and jump to the specified function.

; On return, we restore the stack pointer to its original location.

;

; Destroys no working registers.

;****************************************************************************

; INT64 EbcLLCALLEXNative(UINTN FuncAddr, UINTN NewStackPointer, VOID *FramePtr)

EbcLLCALLEXNative PROC PUBLIC

push rbp

push rbx

mov rbp, rsp

; Function prolog

; Copy FuncAddr to a preserved register.

mov rbx, rcx

; Set stack pointer to new value

sub r8, rdx

sub rsp, r8

mov rcx, rsp

sub rsp, 20h

call CopyMem

add rsp, 20h

; Considering the worst case, load 4 potiential arguments

; into registers.

mov rcx, qword ptr [rsp]

mov rdx, qword ptr [rsp+8h]

mov r8, qword ptr [rsp+10h]

mov r9, qword ptr [rsp+18h]

; Now call the external routine

call rbx

; Function epilog

mov rsp, rbp

pop rbx

pop rbp

ret

EbcLLCALLEXNative ENDP

;****************************************************************************

; EbcLLEbcInterpret

;

; Begin executing an EBC image.

;****************************************************************************

; UINT64 EbcLLEbcInterpret(VOID)

EbcLLEbcInterpret PROC PUBLIC

;

;; mov rax, ca112ebccall2ebch

;; mov r10, EbcEntryPoint

;; mov r11, EbcLLEbcInterpret

;; jmp r11

;

; Caller uses above instruction to jump here

; The stack is below:

; +-----------+

; | RetAddr |

; +-----------+

; |EntryPoint | (R10)

; +-----------+

; | Arg1 | <- RDI

; +-----------+

; | Arg2 |

; +-----------+

; | ... |

; +-----------+

; | Arg16 |

; +-----------+

; | Dummy |

; +-----------+

; | RDI |

; +-----------+

; | RSI |

; +-----------+

; | RBP | <- RBP

; +-----------+

; | RetAddr | <- RSP is here

; +-----------+

; | Scratch1 | (RCX) <- RSI

; +-----------+

; | Scratch2 | (RDX)

; +-----------+

; | Scratch3 | (R8)

; +-----------+

; | Scratch4 | (R9)

; +-----------+

; | Arg5 |

; +-----------+

; | Arg6 |

; +-----------+

; | ... |

; +-----------+

; | Arg16 |

; +-----------+

;

; save old parameter to stack

mov [rsp + 08h], rcx

mov [rsp + 10h], rdx

mov [rsp + 18h], r8

mov [rsp + 20h], r9

; Construct new stack

push rbp

mov rbp, rsp

push rsi

push rdi

push rbx

sub rsp, 80h

push r10

mov rsi, rbp

add rsi, 10h

mov rdi, rsp

add rdi, 8

mov rcx, 16

rep movsq

; build new paramater calling convention

mov r9, [rsp + 18h]

mov r8, [rsp + 10h]

mov rdx, [rsp + 08h]

mov rcx, r10

; call C-code

call EbcInterpret

add rsp, 88h

pop rbx

pop rdi

pop rsi

pop rbp

ret

EbcLLEbcInterpret ENDP

;****************************************************************************

; EbcLLExecuteEbcImageEntryPoint

;

; Begin executing an EBC image.

;****************************************************************************

; UINT64 EbcLLExecuteEbcImageEntryPoint(VOID)

EbcLLExecuteEbcImageEntryPoint PROC PUBLIC

;

;; mov rax, ca112ebccall2ebch

;; mov r10, EbcEntryPoint

;; mov r11, EbcLLExecuteEbcImageEntryPoint

;; jmp r11

;

; Caller uses above instruction to jump here

; The stack is below:

; +-----------+

; | RetAddr |

; +-----------+

; |EntryPoint | (R10)

; +-----------+

; |ImageHandle|

; +-----------+

; |SystemTable|

; +-----------+

; | Dummy |

; +-----------+

; | Dummy |

; +-----------+

; | RetAddr | <- RSP is here

; +-----------+

; |ImageHandle| (RCX)

; +-----------+

; |SystemTable| (RDX)

; +-----------+

;

; build new paramater calling convention

mov r8, rdx

mov rdx, rcx

mov rcx, r10

; call C-code

sub rsp, 28h

call ExecuteEbcImageEntryPoint

add rsp, 28h

ret

EbcLLExecuteEbcImageEntryPoint ENDP

END