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qemu/linux-user/vm86.c
pbrook 53a5960aad Avoid accessing guest memory directly in usermode emulation. 
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1790 c046a42c-6fe2-441c-8c8c-71466251a162
2006-03-25 19:31:22 +00:00

483 lines
15 KiB
C
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/*
* vm86 linux syscall support
*
* Copyright (c) 2003 Fabrice Bellard
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include "qemu.h"
//#define DEBUG_VM86
#define set_flags(X,new,mask) \
((X) = ((X) & ~(mask)) | ((new) & (mask)))
#define SAFE_MASK (0xDD5)
#define RETURN_MASK (0xDFF)
static inline int is_revectored(int nr, struct target_revectored_struct *bitmap)
{
return (((uint8_t *)bitmap)[nr >> 3] >> (nr & 7)) & 1;
}
static inline void vm_putw(uint8_t *segptr, unsigned int reg16, unsigned int val)
{
stw(segptr + (reg16 & 0xffff), val);
}
static inline void vm_putl(uint8_t *segptr, unsigned int reg16, unsigned int val)
{
stl(segptr + (reg16 & 0xffff), val);
}
static inline unsigned int vm_getw(uint8_t *segptr, unsigned int reg16)
{
return lduw(segptr + (reg16 & 0xffff));
}
static inline unsigned int vm_getl(uint8_t *segptr, unsigned int reg16)
{
return ldl(segptr + (reg16 & 0xffff));
}
void save_v86_state(CPUX86State *env)
{
TaskState *ts = env->opaque;
struct target_vm86plus_struct * target_v86;
lock_user_struct(target_v86, ts->target_v86, 0);
/* put the VM86 registers in the userspace register structure */
target_v86->regs.eax = tswap32(env->regs[R_EAX]);
target_v86->regs.ebx = tswap32(env->regs[R_EBX]);
target_v86->regs.ecx = tswap32(env->regs[R_ECX]);
target_v86->regs.edx = tswap32(env->regs[R_EDX]);
target_v86->regs.esi = tswap32(env->regs[R_ESI]);
target_v86->regs.edi = tswap32(env->regs[R_EDI]);
target_v86->regs.ebp = tswap32(env->regs[R_EBP]);
target_v86->regs.esp = tswap32(env->regs[R_ESP]);
target_v86->regs.eip = tswap32(env->eip);
target_v86->regs.cs = tswap16(env->segs[R_CS].selector);
target_v86->regs.ss = tswap16(env->segs[R_SS].selector);
target_v86->regs.ds = tswap16(env->segs[R_DS].selector);
target_v86->regs.es = tswap16(env->segs[R_ES].selector);
target_v86->regs.fs = tswap16(env->segs[R_FS].selector);
target_v86->regs.gs = tswap16(env->segs[R_GS].selector);
set_flags(env->eflags, ts->v86flags, VIF_MASK | ts->v86mask);
target_v86->regs.eflags = tswap32(env->eflags);
unlock_user_struct(target_v86, ts->target_v86, 1);
#ifdef DEBUG_VM86
fprintf(logfile, "save_v86_state: eflags=%08x cs:ip=%04x:%04x\n",
env->eflags, env->segs[R_CS].selector, env->eip);
#endif
/* restore 32 bit registers */
env->regs[R_EAX] = ts->vm86_saved_regs.eax;
env->regs[R_EBX] = ts->vm86_saved_regs.ebx;
env->regs[R_ECX] = ts->vm86_saved_regs.ecx;
env->regs[R_EDX] = ts->vm86_saved_regs.edx;
env->regs[R_ESI] = ts->vm86_saved_regs.esi;
env->regs[R_EDI] = ts->vm86_saved_regs.edi;
env->regs[R_EBP] = ts->vm86_saved_regs.ebp;
env->regs[R_ESP] = ts->vm86_saved_regs.esp;
env->eflags = ts->vm86_saved_regs.eflags;
env->eip = ts->vm86_saved_regs.eip;
cpu_x86_load_seg(env, R_CS, ts->vm86_saved_regs.cs);
cpu_x86_load_seg(env, R_SS, ts->vm86_saved_regs.ss);
cpu_x86_load_seg(env, R_DS, ts->vm86_saved_regs.ds);
cpu_x86_load_seg(env, R_ES, ts->vm86_saved_regs.es);
cpu_x86_load_seg(env, R_FS, ts->vm86_saved_regs.fs);
cpu_x86_load_seg(env, R_GS, ts->vm86_saved_regs.gs);
}
/* return from vm86 mode to 32 bit. The vm86() syscall will return
'retval' */
static inline void return_to_32bit(CPUX86State *env, int retval)
{
#ifdef DEBUG_VM86
fprintf(logfile, "return_to_32bit: ret=0x%x\n", retval);
#endif
save_v86_state(env);
env->regs[R_EAX] = retval;
}
static inline int set_IF(CPUX86State *env)
{
TaskState *ts = env->opaque;
ts->v86flags |= VIF_MASK;
if (ts->v86flags & VIP_MASK) {
return_to_32bit(env, TARGET_VM86_STI);
return 1;
}
return 0;
}
static inline void clear_IF(CPUX86State *env)
{
TaskState *ts = env->opaque;
ts->v86flags &= ~VIF_MASK;
}
static inline void clear_TF(CPUX86State *env)
{
env->eflags &= ~TF_MASK;
}
static inline void clear_AC(CPUX86State *env)
{
env->eflags &= ~AC_MASK;
}
static inline int set_vflags_long(unsigned long eflags, CPUX86State *env)
{
TaskState *ts = env->opaque;
set_flags(ts->v86flags, eflags, ts->v86mask);
set_flags(env->eflags, eflags, SAFE_MASK);
if (eflags & IF_MASK)
return set_IF(env);
else
clear_IF(env);
return 0;
}
static inline int set_vflags_short(unsigned short flags, CPUX86State *env)
{
TaskState *ts = env->opaque;
set_flags(ts->v86flags, flags, ts->v86mask & 0xffff);
set_flags(env->eflags, flags, SAFE_MASK);
if (flags & IF_MASK)
return set_IF(env);
else
clear_IF(env);
return 0;
}
static inline unsigned int get_vflags(CPUX86State *env)
{
TaskState *ts = env->opaque;
unsigned int flags;
flags = env->eflags & RETURN_MASK;
if (ts->v86flags & VIF_MASK)
flags |= IF_MASK;
flags |= IOPL_MASK;
return flags | (ts->v86flags & ts->v86mask);
}
#define ADD16(reg, val) reg = (reg & ~0xffff) | ((reg + (val)) & 0xffff)
/* handle VM86 interrupt (NOTE: the CPU core currently does not
support TSS interrupt revectoring, so this code is always executed) */
static void do_int(CPUX86State *env, int intno)
{
TaskState *ts = env->opaque;
uint32_t *int_ptr, segoffs;
uint8_t *ssp;
unsigned int sp;
if (env->segs[R_CS].selector == TARGET_BIOSSEG)
goto cannot_handle;
if (is_revectored(intno, &ts->vm86plus.int_revectored))
goto cannot_handle;
if (intno == 0x21 && is_revectored((env->regs[R_EAX] >> 8) & 0xff,
&ts->vm86plus.int21_revectored))
goto cannot_handle;
int_ptr = (uint32_t *)(intno << 2);
segoffs = tswap32(*int_ptr);
if ((segoffs >> 16) == TARGET_BIOSSEG)
goto cannot_handle;
#if defined(DEBUG_VM86)
fprintf(logfile, "VM86: emulating int 0x%x. CS:IP=%04x:%04x\n",
intno, segoffs >> 16, segoffs & 0xffff);
#endif
/* save old state */
ssp = (uint8_t *)(env->segs[R_SS].selector << 4);
sp = env->regs[R_ESP] & 0xffff;
vm_putw(ssp, sp - 2, get_vflags(env));
vm_putw(ssp, sp - 4, env->segs[R_CS].selector);
vm_putw(ssp, sp - 6, env->eip);
ADD16(env->regs[R_ESP], -6);
/* goto interrupt handler */
env->eip = segoffs & 0xffff;
cpu_x86_load_seg(env, R_CS, segoffs >> 16);
clear_TF(env);
clear_IF(env);
clear_AC(env);
return;
cannot_handle:
#if defined(DEBUG_VM86)
fprintf(logfile, "VM86: return to 32 bits int 0x%x\n", intno);
#endif
return_to_32bit(env, TARGET_VM86_INTx | (intno << 8));
}
void handle_vm86_trap(CPUX86State *env, int trapno)
{
if (trapno == 1 || trapno == 3) {
return_to_32bit(env, TARGET_VM86_TRAP + (trapno << 8));
} else {
do_int(env, trapno);
}
}
#define CHECK_IF_IN_TRAP() \
if ((ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) && \
(ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_TFpendig)) \
newflags |= TF_MASK
#define VM86_FAULT_RETURN \
if ((ts->vm86plus.vm86plus.flags & TARGET_force_return_for_pic) && \
(ts->v86flags & (IF_MASK | VIF_MASK))) \
return_to_32bit(env, TARGET_VM86_PICRETURN); \
return
void handle_vm86_fault(CPUX86State *env)
{
TaskState *ts = env->opaque;
uint8_t *csp, *pc, *ssp;
unsigned int ip, sp, newflags, newip, newcs, opcode, intno;
int data32, pref_done;
csp = (uint8_t *)(env->segs[R_CS].selector << 4);
ip = env->eip & 0xffff;
pc = csp + ip;
ssp = (uint8_t *)(env->segs[R_SS].selector << 4);
sp = env->regs[R_ESP] & 0xffff;
#if defined(DEBUG_VM86)
fprintf(logfile, "VM86 exception %04x:%08x %02x %02x\n",
env->segs[R_CS].selector, env->eip, pc[0], pc[1]);
#endif
data32 = 0;
pref_done = 0;
do {
opcode = csp[ip];
ADD16(ip, 1);
switch (opcode) {
case 0x66: /* 32-bit data */ data32=1; break;
case 0x67: /* 32-bit address */ break;
case 0x2e: /* CS */ break;
case 0x3e: /* DS */ break;
case 0x26: /* ES */ break;
case 0x36: /* SS */ break;
case 0x65: /* GS */ break;
case 0x64: /* FS */ break;
case 0xf2: /* repnz */ break;
case 0xf3: /* rep */ break;
default: pref_done = 1;
}
} while (!pref_done);
/* VM86 mode */
switch(opcode) {
case 0x9c: /* pushf */
if (data32) {
vm_putl(ssp, sp - 4, get_vflags(env));
ADD16(env->regs[R_ESP], -4);
} else {
vm_putw(ssp, sp - 2, get_vflags(env));
ADD16(env->regs[R_ESP], -2);
}
env->eip = ip;
VM86_FAULT_RETURN;
case 0x9d: /* popf */
if (data32) {
newflags = vm_getl(ssp, sp);
ADD16(env->regs[R_ESP], 4);
} else {
newflags = vm_getw(ssp, sp);
ADD16(env->regs[R_ESP], 2);
}
env->eip = ip;
CHECK_IF_IN_TRAP();
if (data32) {
if (set_vflags_long(newflags, env))
return;
} else {
if (set_vflags_short(newflags, env))
return;
}
VM86_FAULT_RETURN;
case 0xcd: /* int */
intno = csp[ip];
ADD16(ip, 1);
env->eip = ip;
if (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) {
if ( (ts->vm86plus.vm86plus.vm86dbg_intxxtab[intno >> 3] >>
(intno &7)) & 1) {
return_to_32bit(env, TARGET_VM86_INTx + (intno << 8));
return;
}
}
do_int(env, intno);
break;
case 0xcf: /* iret */
if (data32) {
newip = vm_getl(ssp, sp) & 0xffff;
newcs = vm_getl(ssp, sp + 4) & 0xffff;
newflags = vm_getl(ssp, sp + 8);
ADD16(env->regs[R_ESP], 12);
} else {
newip = vm_getw(ssp, sp);
newcs = vm_getw(ssp, sp + 2);
newflags = vm_getw(ssp, sp + 4);
ADD16(env->regs[R_ESP], 6);
}
env->eip = newip;
cpu_x86_load_seg(env, R_CS, newcs);
CHECK_IF_IN_TRAP();
if (data32) {
if (set_vflags_long(newflags, env))
return;
} else {
if (set_vflags_short(newflags, env))
return;
}
VM86_FAULT_RETURN;
case 0xfa: /* cli */
env->eip = ip;
clear_IF(env);
VM86_FAULT_RETURN;
case 0xfb: /* sti */
env->eip = ip;
if (set_IF(env))
return;
VM86_FAULT_RETURN;
default:
/* real VM86 GPF exception */
return_to_32bit(env, TARGET_VM86_UNKNOWN);
break;
}
}
int do_vm86(CPUX86State *env, long subfunction, target_ulong vm86_addr)
{
TaskState *ts = env->opaque;
struct target_vm86plus_struct * target_v86;
int ret;
switch (subfunction) {
case TARGET_VM86_REQUEST_IRQ:
case TARGET_VM86_FREE_IRQ:
case TARGET_VM86_GET_IRQ_BITS:
case TARGET_VM86_GET_AND_RESET_IRQ:
gemu_log("qemu: unsupported vm86 subfunction (%ld)\n", subfunction);
ret = -EINVAL;
goto out;
case TARGET_VM86_PLUS_INSTALL_CHECK:
/* NOTE: on old vm86 stuff this will return the error
from verify_area(), because the subfunction is
interpreted as (invalid) address to vm86_struct.
So the installation check works.
*/
ret = 0;
goto out;
}
/* save current CPU regs */
ts->vm86_saved_regs.eax = 0; /* default vm86 syscall return code */
ts->vm86_saved_regs.ebx = env->regs[R_EBX];
ts->vm86_saved_regs.ecx = env->regs[R_ECX];
ts->vm86_saved_regs.edx = env->regs[R_EDX];
ts->vm86_saved_regs.esi = env->regs[R_ESI];
ts->vm86_saved_regs.edi = env->regs[R_EDI];
ts->vm86_saved_regs.ebp = env->regs[R_EBP];
ts->vm86_saved_regs.esp = env->regs[R_ESP];
ts->vm86_saved_regs.eflags = env->eflags;
ts->vm86_saved_regs.eip = env->eip;
ts->vm86_saved_regs.cs = env->segs[R_CS].selector;
ts->vm86_saved_regs.ss = env->segs[R_SS].selector;
ts->vm86_saved_regs.ds = env->segs[R_DS].selector;
ts->vm86_saved_regs.es = env->segs[R_ES].selector;
ts->vm86_saved_regs.fs = env->segs[R_FS].selector;
ts->vm86_saved_regs.gs = env->segs[R_GS].selector;
ts->target_v86 = vm86_addr;
lock_user_struct(target_v86, vm86_addr, 1);
/* build vm86 CPU state */
ts->v86flags = tswap32(target_v86->regs.eflags);
env->eflags = (env->eflags & ~SAFE_MASK) |
(tswap32(target_v86->regs.eflags) & SAFE_MASK) | VM_MASK;
ts->vm86plus.cpu_type = tswapl(target_v86->cpu_type);
switch (ts->vm86plus.cpu_type) {
case TARGET_CPU_286:
ts->v86mask = 0;
break;
case TARGET_CPU_386:
ts->v86mask = NT_MASK | IOPL_MASK;
break;
case TARGET_CPU_486:
ts->v86mask = AC_MASK | NT_MASK | IOPL_MASK;
break;
default:
ts->v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
break;
}
env->regs[R_EBX] = tswap32(target_v86->regs.ebx);
env->regs[R_ECX] = tswap32(target_v86->regs.ecx);
env->regs[R_EDX] = tswap32(target_v86->regs.edx);
env->regs[R_ESI] = tswap32(target_v86->regs.esi);
env->regs[R_EDI] = tswap32(target_v86->regs.edi);
env->regs[R_EBP] = tswap32(target_v86->regs.ebp);
env->regs[R_ESP] = tswap32(target_v86->regs.esp);
env->eip = tswap32(target_v86->regs.eip);
cpu_x86_load_seg(env, R_CS, tswap16(target_v86->regs.cs));
cpu_x86_load_seg(env, R_SS, tswap16(target_v86->regs.ss));
cpu_x86_load_seg(env, R_DS, tswap16(target_v86->regs.ds));
cpu_x86_load_seg(env, R_ES, tswap16(target_v86->regs.es));
cpu_x86_load_seg(env, R_FS, tswap16(target_v86->regs.fs));
cpu_x86_load_seg(env, R_GS, tswap16(target_v86->regs.gs));
ret = tswap32(target_v86->regs.eax); /* eax will be restored at
the end of the syscall */
memcpy(&ts->vm86plus.int_revectored,
&target_v86->int_revectored, 32);
memcpy(&ts->vm86plus.int21_revectored,
&target_v86->int21_revectored, 32);
ts->vm86plus.vm86plus.flags = tswapl(target_v86->vm86plus.flags);
memcpy(&ts->vm86plus.vm86plus.vm86dbg_intxxtab,
target_v86->vm86plus.vm86dbg_intxxtab, 32);
unlock_user_struct(target_v86, vm86_addr, 0);
#ifdef DEBUG_VM86
fprintf(logfile, "do_vm86: cs:ip=%04x:%04x\n",
env->segs[R_CS].selector, env->eip);
#endif
/* now the virtual CPU is ready for vm86 execution ! */
out:
return ret;
}
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