; $Id: guard-vcc.asm $
;; @file
; IPRT - Control Flow Guard related Visual C++ support routines.
;

;
; Copyright (C) 2022-2023 Oracle and/or its affiliates.
;
; This file is part of VirtualBox base platform packages, as
; available from https://www.virtualbox.org.
;
; This program is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation, in version 3 of the
; License.
;
; This program is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
; General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, see <https://www.gnu.org/licenses>.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
; in the VirtualBox distribution, in which case the provisions of the
; CDDL are applicable instead of those of the GPL.
;
; You may elect to license modified versions of this file under the
; terms and conditions of either the GPL or the CDDL or both.
;
; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
;



;*********************************************************************************************************************************
;*      Header Files                                                                                                             *
;*********************************************************************************************************************************
%include "iprt/asmdefs.mac"
%include "iprt/x86.mac"



;*********************************************************************************************************************************
;*  Global Variables                                                                                                             *
;*********************************************************************************************************************************

;
; Points to a NOP icall checker by default.
; The loader will replace this when we start advertising it in the load config.
;
section .0000cfg rdata align=8

GLOBALNAME __guard_check_icall_fptr
        RTCCPTR_DEF     NAME(__guard_check_icall_nop)

%ifdef RT_ARCH_AMD64
GLOBALNAME __guard_dispatch_icall_fptr
        RTCCPTR_DEF     __guard_dispatch_icall_nop

; xfg stuff (haven't seen it generated or used yet).
GLOBALNAME __guard_xfg_check_icall_fptr
        RTCCPTR_DEF     __guard_check_icall_nop

GLOBALNAME __guard_xfg_dispatch_icall_fptr
        RTCCPTR_DEF     __guard_xfg_dispatch_icall_nop

GLOBALNAME __guard_xfg_table_dispatch_icall_fptr
        RTCCPTR_DEF     __guard_xfg_dispatch_icall_nop

%endif


BEGINCODE
;;
; Check that doesn't do anything.
;
; This is for older windows versions which doesn't support call flow guard stuff.
;
BEGINPROC __guard_check_icall_nop
        ret
ENDPROC   __guard_check_icall_nop

%ifdef RT_ARCH_AMD64
;;
; Target function in RAX
;
; This is for older windows versions which doesn't support call flow guard stuff.
;
BEGINPROC __guard_dispatch_icall_nop
        jmp     rax
ENDPROC   __guard_dispatch_icall_nop
%endif

%ifdef RT_ARCH_AMD64
;;
; Target function in RAX
;
; This is for windows versions which doesn't support extended call flow guard stuff.
;
BEGINPROC __guard_xfg_dispatch_icall_nop
        jmp     [__guard_dispatch_icall_nop wrt RIP]
ENDPROC   __guard_xfg_dispatch_icall_nop
%endif