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/* $Id: bs3-cmn-RegCtxConvertToRingX.c $ */
/** @file
* BS3Kit - Bs3RegCtxConvertToRingX
*/
/*
* 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
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include "bs3kit-template-header.h"
/**
* Transforms a real mode segment into a protected mode selector.
*
* @returns Protected mode selector.
* @param uSeg The real mode segment.
* @param bRing The target ring.
*/
static uint16_t bs3RegCtxConvertRealSegToRingX(uint16_t uSeg, uint8_t bRing)
{
uint16_t uSel;
if ( uSeg == 0
|| uSeg == BS3_SEL_R0_SS16)
uSel = BS3_SEL_R0_SS16 + ((uint16_t)bRing << BS3_SEL_RING_SHIFT);
else if ( uSeg == (BS3_ADDR_BS3TEXT16 >> 4)
|| uSeg == BS3_SEL_R0_CS16)
uSel = BS3_SEL_R0_CS16 + ((uint16_t)bRing << BS3_SEL_RING_SHIFT);
else if ( uSeg == (BS3_ADDR_BS3DATA16 >> 4)
|| uSeg == BS3_SEL_R0_DS16)
uSel = BS3_SEL_R0_DS16 + ((uint16_t)bRing << BS3_SEL_RING_SHIFT);
else if (uSeg == (BS3_ADDR_BS3SYSTEM16 >> 4))
uSel = BS3_SEL_SYSTEM16;
else if (!(uSeg & 0xfff))
uSel = (uSeg >> (12 - X86_SEL_SHIFT)) + BS3_SEL_TILED;
else if (uSeg == BS3_SEL_R0_DS16)
uSel = (uSeg >> (12 - X86_SEL_SHIFT)) + BS3_SEL_TILED;
else
{
Bs3Printf("uSeg=%#x\n", uSeg);
BS3_ASSERT(0);
return 0;
}
uSel |= bRing;
return uSel;
}
/**
* Transforms a protected mode selector to a different ring.
*
* @returns Adjusted protected mode selector.
* @param uSel The current selector value.
* @param bRing The target ring.
* @param iReg Register index.
*/
static uint16_t bs3RegCtxConvertProtSelToRingX(uint16_t uSel, uint8_t bRing, uint8_t iReg)
{
if ( uSel > X86_SEL_RPL
&& !(uSel & X86_SEL_LDT) )
{
if (uSel >= BS3_SEL_R0_FIRST && uSel < BS3_SEL_R0_FIRST + (5 << BS3_SEL_RING_SHIFT))
{
/* Convert BS3_SEL_R*_XXX to the target ring. */
uSel &= BS3_SEL_RING_SUB_MASK;
uSel |= bRing;
uSel += BS3_SEL_R0_FIRST;
uSel += (uint16_t)bRing << BS3_SEL_RING_SHIFT;
}
else
{
/* Convert TEXT16 and DATA16 to BS3_SEL_R*_XXX. */
uint16_t const uSelRaw = uSel & X86_SEL_MASK_OFF_RPL;
if (uSelRaw == BS3_SEL_TEXT16)
uSel = (BS3_SEL_R0_CS16 | bRing) + ((uint16_t)bRing << BS3_SEL_RING_SHIFT);
else if (uSelRaw == BS3_SEL_DATA16)
uSel = (BS3_SEL_R0_DS16 | bRing) + ((uint16_t)bRing << BS3_SEL_RING_SHIFT);
/* CS and SS must have CPL == DPL. So, convert to standard selectors as we're
usually here because Bs3SwitchToRing0 was called to get out of a test situation. */
else if (iReg == X86_SREG_CS || iReg == X86_SREG_SS)
{
if ( Bs3Gdt[uSel >> X86_SEL_SHIFT].Gen.u1Long
&& BS3_MODE_IS_64BIT_SYS(g_bBs3CurrentMode) )
uSel = iReg == X86_SREG_CS ? BS3_SEL_R0_CS64 : BS3_SEL_R0_DS64;
else
{
uint32_t uFlat = Bs3SelFar32ToFlat32(0, uSel);
bool fDefBig = Bs3Gdt[uSel >> X86_SEL_SHIFT].Gen.u1DefBig;
if (!fDefBig && uFlat == BS3_ADDR_BS3TEXT16 && iReg == X86_SREG_CS)
uSel = BS3_SEL_R0_CS16;
else if (!fDefBig && uFlat == 0 && iReg == X86_SREG_SS)
uSel = BS3_SEL_R0_SS16;
else if (fDefBig && uFlat == 0)
uSel = iReg == X86_SREG_CS ? BS3_SEL_R0_CS32 : BS3_SEL_R0_SS32;
else
{
Bs3Printf("uSel=%#x iReg=%d\n", uSel, iReg);
BS3_ASSERT(0);
return uSel;
}
uSel |= bRing;
uSel += (uint16_t)bRing << BS3_SEL_RING_SHIFT;
}
}
/* Adjust the RPL on tiled and MMIO selectors. */
else if ( uSelRaw == BS3_SEL_VMMDEV_MMIO16
|| uSelRaw >= BS3_SEL_TILED)
uSel = uSelRaw | bRing;
}
}
return uSel;
}
/**
* Transforms a register context to a different ring.
*
* @param pRegCtx The register context.
* @param bRing The target ring (0..3).
*
* @note Do _NOT_ call this for creating real mode or v8086 contexts, because
* it will always output a protected mode context!
*/
#undef Bs3RegCtxConvertToRingX
BS3_CMN_DEF(void, Bs3RegCtxConvertToRingX,(PBS3REGCTX pRegCtx, uint8_t bRing))
{
if ( (pRegCtx->rflags.u32 & X86_EFL_VM)
|| pRegCtx->bMode == BS3_MODE_RM)
{
pRegCtx->rflags.u32 &= ~X86_EFL_VM;
pRegCtx->bMode &= ~BS3_MODE_CODE_MASK;
pRegCtx->bMode |= BS3_MODE_CODE_16;
pRegCtx->cs = bs3RegCtxConvertRealSegToRingX(pRegCtx->cs, bRing);
pRegCtx->ss = bs3RegCtxConvertRealSegToRingX(pRegCtx->ss, bRing);
pRegCtx->ds = bs3RegCtxConvertRealSegToRingX(pRegCtx->ds, bRing);
pRegCtx->es = bs3RegCtxConvertRealSegToRingX(pRegCtx->es, bRing);
pRegCtx->fs = bs3RegCtxConvertRealSegToRingX(pRegCtx->fs, bRing);
pRegCtx->gs = bs3RegCtxConvertRealSegToRingX(pRegCtx->gs, bRing);
}
else
{
pRegCtx->cs = bs3RegCtxConvertProtSelToRingX(pRegCtx->cs, bRing, X86_SREG_CS);
pRegCtx->ss = bs3RegCtxConvertProtSelToRingX(pRegCtx->ss, bRing, X86_SREG_SS);
pRegCtx->ds = bs3RegCtxConvertProtSelToRingX(pRegCtx->ds, bRing, X86_SREG_DS);
pRegCtx->es = bs3RegCtxConvertProtSelToRingX(pRegCtx->es, bRing, X86_SREG_ES);
pRegCtx->fs = bs3RegCtxConvertProtSelToRingX(pRegCtx->fs, bRing, X86_SREG_FS);
pRegCtx->gs = bs3RegCtxConvertProtSelToRingX(pRegCtx->gs, bRing, X86_SREG_GS);
}
pRegCtx->bCpl = bRing;
}
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