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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:17:27 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:17:27 +0000
commitf215e02bf85f68d3a6106c2a1f4f7f063f819064 (patch)
tree6bb5b92c046312c4e95ac2620b10ddf482d3fa8b /src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SelProtModeCodeToRealMode.asm
parentInitial commit. (diff)
downloadvirtualbox-f215e02bf85f68d3a6106c2a1f4f7f063f819064.tar.xz
virtualbox-f215e02bf85f68d3a6106c2a1f4f7f063f819064.zip
Adding upstream version 7.0.14-dfsg.upstream/7.0.14-dfsg
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SelProtModeCodeToRealMode.asm')
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diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SelProtModeCodeToRealMode.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-SelProtModeCodeToRealMode.asm
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+; $Id: bs3-cmn-SelProtModeCodeToRealMode.asm $
+;; @file
+; BS3Kit - Bs3SelProtModeCodeToRealMode.
+;
+
+;
+; Copyright (C) 2007-2023 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
+;
+
+%include "bs3kit-template-header.mac"
+
+;
+; Make sure we can get at all the segments.
+;
+BS3_BEGIN_TEXT16
+BS3_BEGIN_RMTEXT16
+BS3_BEGIN_X0TEXT16
+BS3_BEGIN_X1TEXT16
+TMPL_BEGIN_TEXT
+
+
+;;
+; @cproto BS3_CMN_PROTO(uint16_t, Bs3SelProtModeCodeToRealMode,(uint16_t uRealSel), false);
+; @uses ax (return register)
+;
+BS3_PROC_BEGIN_CMN Bs3SelProtModeCodeToRealMode, BS3_PBC_NEAR
+ BS3_CALL_CONV_PROLOG 1
+ push xBP
+ mov xBP, xSP
+
+ ; Load it and mask off the RPL.
+ mov ax, [xBP + xCB + cbCurRetAddr]
+ and ax, X86_SEL_MASK_OFF_RPL
+
+ ; We're allowed to use the real-mode segment value.
+ cmp ax, CGROUP16
+ je .bs3text16
+
+ ; Check for typical code segments.
+ cmp ax, BS3_SEL_R0_CS16
+ je .bs3text16
+ cmp ax, BS3_SEL_RMTEXT16_CS
+ je .bs3rmtext16
+ cmp ax, BS3_SEL_X0TEXT16_CS
+ je .bs3x0text16
+ cmp ax, BS3_SEL_X1TEXT16_CS
+ je .bs3x1text16
+
+ ; Check for less common BS3_SEL_R*_CS16_* values.
+ cmp ax, BS3_SEL_R0_FIRST
+ jb .panic
+ cmp ax, BS3_SEL_R3_FIRST + (1 << BS3_SEL_RING_SHIFT)
+ jae .panic
+
+ ; Since the relevant bits now are the lower 8 ones, we skip the
+ ; AND AX, BS3_SEL_RING_SHIFT
+ ; ADD AX, BS3_SEL_R0_FIRST
+ ; bits and compare AL with lower 8-bit of the BS3_SEL_R0_CS16* values.
+AssertCompile(BS3_SEL_RING_SHIFT == 8)
+ cmp al, BS3_SEL_R0_CS16 & 0xff
+ je .bs3text16
+ cmp al, BS3_SEL_R0_CS16_EO & 0xff
+ je .bs3text16
+ cmp ax, BS3_SEL_R0_CS16_CNF & 0xff
+ je .bs3text16
+ cmp ax, BS3_SEL_R0_CS16_CNF_EO & 0xff
+ je .bs3text16
+.panic:
+ extern BS3_CMN_NM(Bs3Panic)
+ call BS3_CMN_NM(Bs3Panic)
+ jmp .return
+
+.bs3x1text16:
+ mov ax, BS3GROUPX1TEXT16
+ jmp .return
+.bs3x0text16:
+ mov ax, BS3GROUPX0TEXT16
+ jmp .return
+.bs3rmtext16:
+ mov ax, BS3GROUPRMTEXT16
+ jmp .return
+.bs3text16:
+ mov ax, CGROUP16
+.return:
+ pop xBP
+ BS3_CALL_CONV_EPILOG 1
+ BS3_HYBRID_RET
+BS3_PROC_END_CMN Bs3SelProtModeCodeToRealMode
+
+;
+; We may be using the near code in some critical code paths, so don't
+; penalize it.
+;
+BS3_CMN_FAR_STUB Bs3SelProtModeCodeToRealMode, 2
+