diff options
Diffstat (limited to 'src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchToRingX.asm')
| -rw-r--r-- | src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchToRingX.asm | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchToRingX.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchToRingX.asm new file mode 100644 index 00000000..b683779c --- /dev/null +++ b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SwitchToRingX.asm @@ -0,0 +1,103 @@ +; $Id: bs3-cmn-SwitchToRingX.asm $ +;; @file +; BS3Kit - Bs3SwitchToRingX +; + +; +; Copyright (C) 2007-2022 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 +; + +%include "bs3kit-template-header.mac" + + +BS3_EXTERN_CMN Bs3Syscall +%if TMPL_BITS == 16 +BS3_EXTERN_DATA16 g_bBs3CurrentMode +%endif +TMPL_BEGIN_TEXT + + +;; +; @cproto BS3_DECL(void) Bs3SwitchToRingX(uint8_t bRing); +; +; @param bRing The target ring (0..3). +; @remarks Does not require 20h of parameter scratch space in 64-bit mode. +; +; @uses No GPRs. +; +BS3_PROC_BEGIN_CMN Bs3SwitchToRingX, BS3_PBC_HYBRID_SAFE + BS3_CALL_CONV_PROLOG 1 + push xBP + mov xBP, xSP + push xAX + +%if TMPL_BITS == 16 + ; Check the current mode. + mov al, [BS3_DATA16_WRT(g_bBs3CurrentMode)] + + ; If real mode: Nothing we can do, but we'll bitch if the request isn't for ring-0. + cmp al, BS3_MODE_RM + je .return_real_mode + + ; If V8086 mode: Always do syscall and add a lock prefix to make sure it gets to the VMM. + test al, BS3_MODE_CODE_V86 + jnz .just_do_it +%endif + + ; In protected mode: Check the CPL we're currently at skip syscall if ring-0 already. + mov ax, cs + and al, 3 + cmp al, byte [xBP + xCB + cbCurRetAddr] + je .return + +.just_do_it: + mov xAX, BS3_SYSCALL_TO_RING0 + add al, [xBP + xCB + cbCurRetAddr] + call Bs3Syscall + +%ifndef BS3_STRICT +.return_real_mode: +%endif +.return: + pop xAX + pop xBP + BS3_CALL_CONV_EPILOG 1 + BS3_HYBRID_RET + +%ifdef BS3_STRICT +; In real mode, only ring-0 makes any sense. +.return_real_mode: + cmp byte [xBP + xCB + cbCurRetAddr], 0 + je .return + int3 + jmp .return +%endif +BS3_PROC_END_CMN Bs3SwitchToRingX + |