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/*
* plex86: run multiple x86 operating systems concurrently
* Copyright (C) 1999-2001 Kevin P. Lawton
*
* segment-mon.c: access memory using virtual (seg:offset) ptr
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "plex86.h"
#define IN_MONITOR_SPACE
#include "monitor.h"
// xxx Could add code for REP string ops
void
copyGuestDescToMon(vm_t *vm, unsigned sreg)
{
// xxx What checks prevent CS: for writes?
// xxx CS writable in RM
// xxx Could optimize reload of seg if same desc as before
// xxx Maybe we should check valid/p bits.
/* If seg is CS, convert to data descriptor. */
{
/* This stuff needs to be done with interrupts off, otherwise
* interrupts will cause monitor->host->monitor switches, will
* reload a partially initialized descriptor!
*/
asm volatile ( "cli\n\t" );
vm->guest.addr.gdt[4+sreg] = vm->guest_cpu.desc_cache[sreg].desc;
vm->guest.addr.gdt[4+sreg].dpl = 3;
if (sreg==SRegCS) {
/* When the guest CS descriptor cache is loaded, load the FS
* descriptor with the virtualized descriptor.
*/
vm->guest.addr.gdt[4+sreg].type = D_DATA | D_WRITE | D_ACCESSED;
asm volatile ("movl %0, %%fs \n\t"
:
: "r" (Selector(4+sreg,0,RPL3))
);
}
else {
vm->guest.addr.gdt[4+sreg].type =
vm->guest_cpu.desc_cache[sreg].desc.type;
}
asm volatile ( "sti\n\t" );
}
}
/* NOTE: I make use of the fact that GCC caller-saves certain registers,
* so we are free to clobber them here. This eliminates extra push/pop
* instructions.
*/
/* Fetch routines. Stack:
* offset32
* [return address]
*/
asm (
".globl __fetchCheckNative \n\t"
"__fetchCheckNative: \n\t"
"movl 4(%esp), %eax \n\t" /* Guest offset. */
".globl __fetchCheckAttempt \n\t"
"__fetchCheckAttempt: \n\t"
"fs; movb (%eax), %al \n\t" /* Read byte using seg:offset. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
);
/* Read routines. Stack:
* data pointer
* offset32
* selector
* [return address]
*/
asm (
".globl __readByteNative \n\t"
"__readByteNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Ptr to store result. */
".globl __readByteAttempt \n\t"
"__readByteAttempt: \n\t"
"gs; movb (%eax), %al \n\t" /* Read byte using seg:offset. */
"movb %al, (%edx) \n\t" /* Store byte using ptr. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
".globl __readError \n\t"
"__readError: \n\t"
"movl $0, %eax \n\t" /* Return Error. */
"ret \n\t"
);
asm (
".globl __readWordNative \n\t"
"__readWordNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Ptr to store result. */
".globl __readWordAttempt \n\t"
"__readWordAttempt: \n\t"
"gs; movw (%eax), %ax \n\t" /* Read word using seg:offset. */
"movw %ax, (%edx) \n\t" /* Store word using ptr. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
);
asm (
".globl __readDWordNative \n\t"
"__readDWordNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Ptr to store result. */
".globl __readDWordAttempt \n\t"
"__readDWordAttempt: \n\t"
"gs; movl (%eax), %eax \n\t" /* Read dword using seg:offset. */
"movl %eax, (%edx) \n\t" /* Store dword using ptr. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
);
/* Read-Modify-Write versions of native read functions. */
asm (
".globl __readRMWByteNative \n\t"
"__readRMWByteNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Ptr to store result. */
".globl __readRMWByteAttempt \n\t"
"__readRMWByteAttempt: \n\t"
"gs; orb $0, (%eax) \n\t" /* Test writability of data area. */
"gs; movb (%eax), %al \n\t" /* Read byte using seg:offset. */
"movb %al, (%edx) \n\t" /* Store byte using ptr. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
);
asm (
".globl __readRMWWordNative \n\t"
"__readRMWWordNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Ptr to store result. */
".globl __readRMWWordAttempt \n\t"
"__readRMWWordAttempt: \n\t"
"gs; orw $0, (%eax) \n\t" /* Test writability of data area. */
"gs; movw (%eax), %ax \n\t" /* Read word using seg:offset. */
"movw %ax, (%edx) \n\t" /* Store word using ptr. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
);
asm (
".globl __readRMWDWordNative \n\t"
"__readRMWDWordNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Ptr to store result. */
".globl __readRMWDWordAttempt \n\t"
"__readRMWDWordAttempt: \n\t"
"gs; orl $0, (%eax) \n\t" /* Test writability of data area. */
"gs; movl (%eax), %eax \n\t" /* Read dword using seg:offset. */
"movl %eax, (%edx) \n\t" /* Store dword using ptr. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
);
/* Write routines. */
asm (
".globl __writeByteNative \n\t"
"__writeByteNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Data ptr. */
"movb (%edx), %dl \n\t" /* Get byte using data ptr. */
".globl __writeByteAttempt \n\t"
"__writeByteAttempt: \n\t"
"gs; movb %dl, (%eax) \n\t" /* Write byte using seg:offset. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
".globl __writeError \n\t"
"__writeError: \n\t"
"movl $0, %eax \n\t" /* Return Error. */
"ret \n\t"
);
asm (
".globl __writeWordNative \n\t"
"__writeWordNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Data ptr. */
"movw (%edx), %dx \n\t" /* Get word using data ptr. */
".globl __writeWordAttempt \n\t"
"__writeWordAttempt: \n\t"
"gs; movw %dx, (%eax) \n\t" /* Write word using seg:offset. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
);
asm (
".globl __writeDWordNative \n\t"
"__writeDWordNative: \n\t"
"movl 4(%esp), %gs \n\t"
"movl 8(%esp), %eax \n\t" /* Guest offset. */
"movl 12(%esp), %edx \n\t" /* Data ptr. */
"movl (%edx), %edx \n\t" /* Get dword using data ptr. */
".globl __writeDWordAttempt \n\t"
"__writeDWordAttempt: \n\t"
"gs; movl %edx, (%eax) \n\t" /* Write dword using seg:offset. */
"movl $1, %eax \n\t" /* Return OK. */
"ret \n\t"
);
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