| 1 | /* $Id: bs3-cmn-TrapRmV86Init.c 106061 2024-09-16 14:03:52Z vboxsync $ */
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| 2 | /** @file
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| 3 | * BS3Kit - Bs3TrapRmV86Init
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2007-2024 Oracle and/or its affiliates.
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| 8 | *
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| 9 | * This file is part of VirtualBox base platform packages, as
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| 10 | * available from https://www.virtualbox.org.
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| 11 | *
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| 12 | * This program is free software; you can redistribute it and/or
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| 13 | * modify it under the terms of the GNU General Public License
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| 14 | * as published by the Free Software Foundation, in version 3 of the
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| 15 | * License.
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| 16 | *
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| 17 | * This program is distributed in the hope that it will be useful, but
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| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | * General Public License for more details.
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| 21 | *
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| 22 | * You should have received a copy of the GNU General Public License
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| 23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | *
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| 25 | * The contents of this file may alternatively be used under the terms
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| 26 | * of the Common Development and Distribution License Version 1.0
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| 27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 28 | * in the VirtualBox distribution, in which case the provisions of the
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| 29 | * CDDL are applicable instead of those of the GPL.
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| 30 | *
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| 31 | * You may elect to license modified versions of this file under the
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| 32 | * terms and conditions of either the GPL or the CDDL or both.
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| 33 | *
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| 34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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| 35 | */
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| 36 |
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| 37 |
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| 38 | /*********************************************************************************************************************************
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| 39 | * Header Files *
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| 40 | *********************************************************************************************************************************/
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| 41 | #include "bs3kit-template-header.h"
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| 42 |
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| 43 |
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| 44 | /*********************************************************************************************************************************
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| 45 | * Global Variables *
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| 46 | *********************************************************************************************************************************/
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| 47 | /* We ASSUME that BS3CLASS16CODE is 64KB aligned, so the low 16-bit of the
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| 48 | flat address matches. Also, these symbols are defined both with
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| 49 | and without underscore prefixes. */
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| 50 | extern BS3_DECL(void) BS3_FAR_CODE Bs3TrapRmV86GenericEntries(void);
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| 51 |
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| 52 | /* These two are ugly. Need data access for patching purposes. */
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| 53 | extern uint8_t BS3_FAR_DATA bs3TrapRmV86GenericTrapOrInt[];
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| 54 |
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| 55 | /* bs3-cmn-TrapRmV86Data.c: */
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| 56 | #define g_fBs3RmIvtCopied BS3_DATA_NM(g_fBs3RmIvtCopied)
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| 57 | extern bool g_fBs3RmIvtCopied;
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| 58 |
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| 59 |
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| 60 | #undef Bs3TrapRmV86InitEx
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| 61 | BS3_CMN_DEF(void, Bs3TrapRmV86InitEx,(bool f386Plus))
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| 62 | {
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| 63 | RTFAR16 BS3_FAR *paIvt = Bs3XptrFlatToCurrent(0);
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| 64 | unsigned iIvt;
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| 65 |
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| 66 | /*
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| 67 | * Copy the real mode IVT the first time we are here.
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| 68 | */
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| 69 | if (!g_fBs3RmIvtCopied)
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| 70 | {
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| 71 | Bs3MemCpy(g_aBs3RmIvtOriginal, paIvt, sizeof(g_aBs3RmIvtOriginal));
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| 72 | g_fBs3RmIvtCopied = true;
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| 73 | }
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| 74 | /*
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| 75 | * The rest of the times, we copy back the original and modify it.
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| 76 | */
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| 77 | else
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| 78 | Bs3MemCpy(paIvt, g_aBs3RmIvtOriginal, sizeof(g_aBs3RmIvtOriginal));
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| 79 |
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| 80 |
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| 81 | /*
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| 82 | * If 386 or later, patch the trap handler code to not jump to the 80286
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| 83 | * code but continue with the next instruction (the 386+ code).
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| 84 | */
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| 85 | if (f386Plus)
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| 86 | {
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| 87 | uint8_t BS3_FAR_DATA *pbFunction = &bs3TrapRmV86GenericTrapOrInt[0];
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| 88 | #if ARCH_BITS == 16
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| 89 | if (g_bBs3CurrentMode != BS3_MODE_RM)
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| 90 | pbFunction = (uint8_t BS3_FAR_DATA *)BS3_FP_MAKE(BS3_SEL_TILED + 1, BS3_FP_OFF(pbFunction));
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| 91 | #endif
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| 92 | pbFunction[1] = 0;
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| 93 | pbFunction[2] = 0;
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| 94 | }
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| 95 |
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| 96 | /*
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| 97 | * Since we want to play with V86 mode as well as 8086 and 186 CPUs, we
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| 98 | * cannot move the IVT from its default location. So, modify it in place.
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| 99 | *
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| 100 | * Note! We must keep INT 10h working, which is easy since the CPU does
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| 101 | * use it (well, it's been reserved for 30+ years).
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| 102 | * Turns out we must not hook INT 6Dh either then, as some real VGA
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| 103 | * BIOS installs their INT 10h handler there as well, and seemingly
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| 104 | * must be using it internally or something.
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| 105 | *
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| 106 | * We also keep 15h working for memory interfaces (see bs3-mode-BiosInt15*).
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| 107 | */
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| 108 | for (iIvt = 0; iIvt < 256; iIvt++)
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| 109 | if (iIvt != 0x10 && iIvt != 0x15 && iIvt != 0x6d && iIvt != BS3_TRAP_SYSCALL)
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| 110 | {
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| 111 | paIvt[iIvt].off = (uint16_t)(uintptr_t)Bs3TrapRmV86GenericEntries + iIvt * 8;
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| 112 | paIvt[iIvt].sel = BS3_SEL_TEXT16;
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| 113 | }
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| 114 | }
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| 115 |
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| 116 |
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| 117 | #undef Bs3TrapRmV86Init
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| 118 | BS3_CMN_DEF(void, Bs3TrapRmV86Init,(void))
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| 119 | {
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| 120 | BS3_CMN_NM(Bs3TrapRmV86InitEx)((g_uBs3CpuDetected & BS3CPU_TYPE_MASK) >= BS3CPU_80386);
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| 121 | }
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| 122 |
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