memory/instr.c

   1 /*
   2  * Emulation of privileged instructions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "windef.h"
  22 #include "wingdi.h"
  23 #include "wine/winuser16.h"
  24 #include "module.h"
  25 #include "miscemu.h"
  26 #include "selectors.h"
  27 #include "wine/debug.h"
  28 #include "callback.h"
  29 #include "thread.h"
  30 #include "wine/exception.h"
  31
  32 WINE_DEFAULT_DEBUG_CHANNEL(int);
  33 WINE_DECLARE_DEBUG_CHANNEL(io);
  34
  35 #ifdef __i386__
  36
  37 /* macros to set parts of a DWORD */
  38 #define SET_LOWORD(dw,val)  ((dw) = ((dw) & 0xffff0000) | LOWORD(val))
  39 #define SET_LOBYTE(dw,val)  ((dw) = ((dw) & 0xffffff00) | LOBYTE(val))
  40 #define ADD_LOWORD(dw,val)  ((dw) = ((dw) & 0xffff0000) | LOWORD((DWORD)(dw)+(val)))
  41
  42 inline static void add_stack( CONTEXT86 *context, int offset )
  43 {
  44     if (ISV86(context) || !IS_SELECTOR_32BIT(context->SegSs))
  45         ADD_LOWORD( context->Esp, offset );
  46     else
  47         context->Esp += offset;
  48 }
  49
  50 inline static void *make_ptr( CONTEXT86 *context, DWORD seg, DWORD off, int long_addr )
  51 {
  52     if (ISV86(context)) return PTR_REAL_TO_LIN( seg, off );
  53     if (IS_SELECTOR_SYSTEM(seg)) return (void *)off;
  54     if (!long_addr) off = LOWORD(off);
  55     return (char *) MapSL( MAKESEGPTR( seg, 0 ) ) + off;
  56 }
  57
  58 inline static void *get_stack( CONTEXT86 *context )
  59 {
  60     if (ISV86(context)) return PTR_REAL_TO_LIN( context->SegSs, context->Esp );
  61     return wine_ldt_get_ptr( context->SegSs, context->Esp );
  62 }
  63
  64
  65 /***********************************************************************
  66  *           timer_thread
  67  */
  68 static DWORD CALLBACK timer_thread( void *dummy )
  69 {
  70     for (;;)
  71     {
  72         Sleep(55);
  73         DOSMEM_Tick( 0 );
  74     }
  75 }
  76
  77 /***********************************************************************
  78  *           INSTR_ReplaceSelector
  79  *
  80  * Try to replace an invalid selector by a valid one.
  81  * The only selector where it is allowed to do "mov ax,40;mov es,ax"
  82  * is the so called 'bimodal' selector 0x40, which points to the BIOS
  83  * data segment. Used by (at least) Borland products (and programs compiled
  84  * using Borland products).
  85  *
  86  * See Undocumented Windows, Chapter 5, __0040.
  87  */
  88 static BOOL INSTR_ReplaceSelector( CONTEXT86 *context, WORD *sel )
  89 {
  90     extern char Call16_Start, Call16_End;
  91
  92     if (IS_SELECTOR_SYSTEM(context->SegCs))
  93         if (    (char *)context->Eip >= &Call16_Start
  94              && (char *)context->Eip <  &Call16_End   )
  95         {
  96             /* Saved selector may have become invalid when the relay code */
  97             /* tries to restore it. We simply clear it. */
  98             *sel = 0;
  99             return TRUE;
 100         }
 101
 102     if (*sel == 0x40)
 103     {
 104 #if 0  /* hack until this is moved to kernel */
 105         static WORD sys_timer = 0;
 106         if (!sys_timer)
 107             sys_timer = CreateSystemTimer( 55, DOSMEM_Tick );
 108 #endif
 109         static HANDLE sys_thread;
 110         if (!sys_thread) sys_thread = CreateThread( NULL, 0, timer_thread, NULL, 0, NULL );
 111         *sel = DOSMEM_BiosDataSeg;
 112         return TRUE;
 113     }
 114     return FALSE;  /* Can't replace selector, crashdump */
 115 }
 116
 117
 118 /***********************************************************************
 119  *           INSTR_GetOperandAddr
 120  *
 121  * Return the address of an instruction operand (from the mod/rm byte).
 122  */
 123 static BYTE *INSTR_GetOperandAddr( CONTEXT86 *context, BYTE *instr,
 124                                    int long_addr, int segprefix, int *len )
 125 {
 126     int mod, rm, base, index = 0, ss = 0, seg = 0, off;
 127     LDT_ENTRY entry;
 128
 129 #define GET_VAL(val,type) \
 130     { *val = *(type *)instr; instr += sizeof(type); *len += sizeof(type); }
 131
 132     *len = 0;
 133     GET_VAL( &mod, BYTE );
 134     rm = mod & 7;
 135     mod >>= 6;
 136
 137     if (mod == 3)
 138     {
 139         switch(rm)
 140         {
 141         case 0: return (BYTE *)&context->Eax;
 142         case 1: return (BYTE *)&context->Ecx;
 143         case 2: return (BYTE *)&context->Edx;
 144         case 3: return (BYTE *)&context->Ebx;
 145         case 4: return (BYTE *)&context->Esp;
 146         case 5: return (BYTE *)&context->Ebp;
 147         case 6: return (BYTE *)&context->Esi;
 148         case 7: return (BYTE *)&context->Edi;
 149         }
 150     }
 151
 152     if (long_addr)
 153     {
 154         if (rm == 4)
 155         {
 156             BYTE sib;
 157             GET_VAL( &sib, BYTE );
 158             rm = sib & 7;
 159             ss = sib >> 6;
 160             switch(sib >> 3)
 161             {
 162             case 0: index = context->Eax; break;
 163             case 1: index = context->Ecx; break;
 164             case 2: index = context->Edx; break;
 165             case 3: index = context->Ebx; break;
 166             case 4: index = 0; break;
 167             case 5: index = context->Ebp; break;
 168             case 6: index = context->Esi; break;
 169             case 7: index = context->Edi; break;
 170             }
 171         }
 172
 173         switch(rm)
 174         {
 175         case 0: base = context->Eax; seg = context->SegDs; break;
 176         case 1: base = context->Ecx; seg = context->SegDs; break;
 177         case 2: base = context->Edx; seg = context->SegDs; break;
 178         case 3: base = context->Ebx; seg = context->SegDs; break;
 179         case 4: base = context->Esp; seg = context->SegSs; break;
 180         case 5: base = context->Ebp; seg = context->SegSs; break;
 181         case 6: base = context->Esi; seg = context->SegDs; break;
 182         case 7: base = context->Edi; seg = context->SegDs; break;
 183         }
 184         switch (mod)
 185         {
 186         case 0:
 187             if (rm == 5)  /* special case: ds:(disp32) */
 188             {
 189                 GET_VAL( &base, DWORD );
 190                 seg = context->SegDs;
 191             }
 192             break;
 193
 194         case 1:  /* 8-bit disp */
 195             GET_VAL( &off, BYTE );
 196             base += (signed char)off;
 197             break;
 198
 199         case 2:  /* 32-bit disp */
 200             GET_VAL( &off, DWORD );
 201             base += (signed long)off;
 202             break;
 203         }
 204     }
 205     else  /* short address */
 206     {
 207         switch(rm)
 208         {
 209         case 0:  /* ds:(bx,si) */
 210             base = LOWORD(context->Ebx) + LOWORD(context->Esi);
 211             seg  = context->SegDs;
 212             break;
 213         case 1:  /* ds:(bx,di) */
 214             base = LOWORD(context->Ebx) + LOWORD(context->Edi);
 215             seg  = context->SegDs;
 216             break;
 217         case 2:  /* ss:(bp,si) */
 218             base = LOWORD(context->Ebp) + LOWORD(context->Esi);
 219             seg  = context->SegSs;
 220             break;
 221         case 3:  /* ss:(bp,di) */
 222             base = LOWORD(context->Ebp) + LOWORD(context->Edi);
 223             seg  = context->SegSs;
 224             break;
 225         case 4:  /* ds:(si) */
 226             base = LOWORD(context->Esi);
 227             seg  = context->SegDs;
 228             break;
 229         case 5:  /* ds:(di) */
 230             base = LOWORD(context->Edi);
 231             seg  = context->SegDs;
 232             break;
 233         case 6:  /* ss:(bp) */
 234             base = LOWORD(context->Ebp);
 235             seg  = context->SegSs;
 236             break;
 237         case 7:  /* ds:(bx) */
 238             base = LOWORD(context->Ebx);
 239             seg  = context->SegDs;
 240             break;
 241         }
 242
 243         switch(mod)
 244         {
 245         case 0:
 246             if (rm == 6)  /* special case: ds:(disp16) */
 247             {
 248                 GET_VAL( &base, WORD );
 249                 seg  = context->SegDs;
 250             }
 251             break;
 252
 253         case 1:  /* 8-bit disp */
 254             GET_VAL( &off, BYTE );
 255             base += (signed char)off;
 256             break;
 257
 258         case 2:  /* 16-bit disp */
 259             GET_VAL( &off, WORD );
 260             base += (signed short)off;
 261             break;
 262         }
 263         base &= 0xffff;
 264     }
 265     if (segprefix != -1) seg = segprefix;
 266
 267     /* Make sure the segment and offset are valid */
 268     if (IS_SELECTOR_SYSTEM(seg)) return (BYTE *)(base + (index << ss));
 269     if ((seg & 7) != 7) return NULL;
 270     wine_ldt_get_entry( seg, &entry );
 271     if (wine_ldt_is_empty( &entry )) return NULL;
 272     if (wine_ldt_get_limit(&entry) < (base + (index << ss))) return NULL;
 273     return (char *)wine_ldt_get_base(&entry) + base + (index << ss);
 274 #undef GET_VAL
 275 }
 276
 277
 278 /***********************************************************************
 279  *           INSTR_EmulateLDS
 280  *
 281  * Emulate the LDS (and LES,LFS,etc.) instruction.
 282  */
 283 static BOOL INSTR_EmulateLDS( CONTEXT86 *context, BYTE *instr, int long_op,
 284                               int long_addr, int segprefix, int *len )
 285 {
 286     WORD seg;
 287     BYTE *regmodrm = instr + 1 + (*instr == 0x0f);
 288     BYTE *addr = INSTR_GetOperandAddr( context, regmodrm,
 289                                        long_addr, segprefix, len );
 290     if (!addr)
 291         return FALSE;  /* Unable to emulate it */
 292     seg = *(WORD *)(addr + (long_op ? 4 : 2));
 293
 294     if (!INSTR_ReplaceSelector( context, &seg ))
 295         return FALSE;  /* Unable to emulate it */
 296
 297     /* Now store the offset in the correct register */
 298
 299     switch((*regmodrm >> 3) & 7)
 300     {
 301     case 0:
 302         if (long_op) context->Eax = *(DWORD *)addr;
 303         else SET_LOWORD(context->Eax,*(WORD *)addr);
 304         break;
 305     case 1:
 306         if (long_op) context->Ecx = *(DWORD *)addr;
 307         else SET_LOWORD(context->Ecx,*(WORD *)addr);
 308         break;
 309     case 2:
 310         if (long_op) context->Edx = *(DWORD *)addr;
 311         else SET_LOWORD(context->Edx,*(WORD *)addr);
 312         break;
 313     case 3:
 314         if (long_op) context->Ebx = *(DWORD *)addr;
 315         else SET_LOWORD(context->Ebx,*(WORD *)addr);
 316         break;
 317     case 4:
 318         if (long_op) context->Esp = *(DWORD *)addr;
 319         else SET_LOWORD(context->Esp,*(WORD *)addr);
 320         break;
 321     case 5:
 322         if (long_op) context->Ebp = *(DWORD *)addr;
 323         else SET_LOWORD(context->Ebp,*(WORD *)addr);
 324         break;
 325     case 6:
 326         if (long_op) context->Esi = *(DWORD *)addr;
 327         else SET_LOWORD(context->Esi,*(WORD *)addr);
 328         break;
 329     case 7:
 330         if (long_op) context->Edi = *(DWORD *)addr;
 331         else SET_LOWORD(context->Edi,*(WORD *)addr);
 332         break;
 333     }
 334
 335     /* Store the correct segment in the segment register */
 336
 337     switch(*instr)
 338     {
 339     case 0xc4: context->SegEs = seg; break;  /* les */
 340     case 0xc5: context->SegDs = seg; break;  /* lds */
 341     case 0x0f: switch(instr[1])
 342                {
 343                case 0xb2: context->SegSs = seg; break;  /* lss */
 344                case 0xb4: context->SegFs = seg; break;  /* lfs */
 345                case 0xb5: context->SegGs = seg; break;  /* lgs */
 346                }
 347                break;
 348     }
 349
 350     /* Add the opcode size to the total length */
 351
 352     *len += 1 + (*instr == 0x0f);
 353     return TRUE;
 354 }
 355
 356 /***********************************************************************
 357  *           INSTR_inport
 358  *
 359  * input on a I/O port
 360  */
 361 static DWORD INSTR_inport( WORD port, int size, CONTEXT86 *context )
 362 {
 363     DWORD res = IO_inport( port, size );
 364     if (TRACE_ON(io))
 365     {
 366         switch(size)
 367         {
 368         case 1:
 369             DPRINTF( "0x%x < %02x @ %04x:%04x\n", port, LOBYTE(res),
 370                      (WORD)context->SegCs, LOWORD(context->Eip));
 371             break;
 372         case 2:
 373             DPRINTF( "0x%x < %04x @ %04x:%04x\n", port, LOWORD(res),
 374                      (WORD)context->SegCs, LOWORD(context->Eip));
 375             break;
 376         case 4:
 377             DPRINTF( "0x%x < %08lx @ %04x:%04x\n", port, res,
 378                      (WORD)context->SegCs, LOWORD(context->Eip));
 379             break;
 380         }
 381     }
 382     return res;
 383 }
 384
 385
 386 /***********************************************************************
 387  *           INSTR_outport
 388  *
 389  * output on a I/O port
 390  */
 391 static void INSTR_outport( WORD port, int size, DWORD val, CONTEXT86 *context )
 392 {
 393     IO_outport( port, size, val );
 394     if (TRACE_ON(io))
 395     {
 396         switch(size)
 397         {
 398         case 1:
 399             DPRINTF("0x%x > %02x @ %04x:%04x\n", port, LOBYTE(val),
 400                     (WORD)context->SegCs, LOWORD(context->Eip));
 401             break;
 402         case 2:
 403             DPRINTF("0x%x > %04x @ %04x:%04x\n", port, LOWORD(val),
 404                     (WORD)context->SegCs, LOWORD(context->Eip));
 405             break;
 406         case 4:
 407             DPRINTF("0x%x > %08lx @ %04x:%04x\n", port, val,
 408                     (WORD)context->SegCs, LOWORD(context->Eip));
 409             break;
 410         }
 411     }
 412 }
 413
 414
 415 /***********************************************************************
 416  *           INSTR_EmulateInstruction
 417  *
 418  * Emulate a privileged instruction.
 419  * Returns exception code, or 0 if emulation successful.
 420  */
 421 DWORD INSTR_EmulateInstruction( CONTEXT86 *context )
 422 {
 423     int prefix, segprefix, prefixlen, len, repX, long_op, long_addr;
 424     BYTE *instr;
 425     DWORD ret = EXCEPTION_PRIV_INSTRUCTION;
 426
 427     long_op = long_addr = (!ISV86(context) && IS_SELECTOR_32BIT(context->SegCs));
 428     instr = make_ptr( context, context->SegCs, context->Eip, TRUE );
 429     if (!instr) return ret;
 430
 431     /* First handle any possible prefix */
 432
 433     segprefix = -1;  /* no prefix */
 434     prefix = 1;
 435     repX = 0;
 436     prefixlen = 0;
 437     while(prefix)
 438     {
 439         switch(*instr)
 440         {
 441         case 0x2e:
 442             segprefix = context->SegCs;
 443             break;
 444         case 0x36:
 445             segprefix = context->SegSs;
 446             break;
 447         case 0x3e:
 448             segprefix = context->SegDs;
 449             break;
 450         case 0x26:
 451             segprefix = context->SegEs;
 452             break;
 453         case 0x64:
 454             segprefix = context->SegFs;
 455             break;
 456         case 0x65:
 457             segprefix = context->SegGs;
 458             break;
 459         case 0x66:
 460             long_op = !long_op;  /* opcode size prefix */
 461             break;
 462         case 0x67:
 463             long_addr = !long_addr;  /* addr size prefix */
 464             break;
 465         case 0xf0:  /* lock */
 466             break;
 467         case 0xf2:  /* repne */
 468             repX = 1;
 469             break;
 470         case 0xf3:  /* repe */
 471             repX = 2;
 472             break;
 473         default:
 474             prefix = 0;  /* no more prefixes */
 475             break;
 476         }
 477         if (prefix)
 478         {
 479             instr++;
 480             prefixlen++;
 481         }
 482     }
 483
 484     /* Now look at the actual instruction */
 485
 486     switch(*instr)
 487     {
 488         case 0x07: /* pop es */
 489         case 0x17: /* pop ss */
 490         case 0x1f: /* pop ds */
 491             {
 492                 WORD seg = *(WORD *)get_stack( context );
 493                 if (INSTR_ReplaceSelector( context, &seg ))
 494                 {
 495                     switch(*instr)
 496                     {
 497                     case 0x07: context->SegEs = seg; break;
 498                     case 0x17: context->SegSs = seg; break;
 499                     case 0x1f: context->SegDs = seg; break;
 500                     }
 501                     add_stack(context, long_op ? 4 : 2);
 502                     context->Eip += prefixlen + 1;
 503                     return 0;
 504                 }
 505             }
 506             break;  /* Unable to emulate it */
 507
 508         case 0x0f: /* extended instruction */
 509             switch(instr[1])
 510             {
 511             case 0x22: /* mov eax, crX */
 512                 switch (instr[2]) {
 513                 case 0xc0:
 514                         ERR("mov eax,cr0 at 0x%08lx, EAX=0x%08lx\n",
 515                             context->Eip,context->Eax );
 516                         context->Eip += prefixlen+3;
 517                         return 0;
 518                 default:
 519                         break; /*fallthrough to bad instruction handling */
 520                 }
 521                 break; /*fallthrough to bad instruction handling */
 522             case 0x20: /* mov crX, eax */
 523                 switch (instr[2]) {
 524                 case 0xe0: /* mov cr4, eax */
 525                     /* CR4 register . See linux/arch/i386/mm/init.c, X86_CR4_ defs
 526                      * bit 0: VME       Virtual Mode Exception ?
 527                      * bit 1: PVI       Protected mode Virtual Interrupt
 528                      * bit 2: TSD       Timestamp disable
 529                      * bit 3: DE        Debugging extensions
 530                      * bit 4: PSE       Page size extensions
 531                      * bit 5: PAE   Physical address extension
 532                      * bit 6: MCE       Machine check enable
 533                      * bit 7: PGE   Enable global pages
 534                      * bit 8: PCE       Enable performance counters at IPL3
 535                      */
 536                     ERR("mov cr4,eax at 0x%08lx\n",context->Eip);
 537                     context->Eax = 0;
 538                     context->Eip += prefixlen+3;
 539                     return 0;
 540                 case 0xc0: /* mov cr0, eax */
 541                     ERR("mov cr0,eax at 0x%08lx\n",context->Eip);
 542                     context->Eax = 0x10; /* FIXME: set more bits ? */
 543                     context->Eip += prefixlen+3;
 544                     return 0;
 545                 default: /* fallthrough to illegal instruction */
 546                     break;
 547                 }
 548                 /* fallthrough to illegal instruction */
 549                 break;
 550             case 0xa1: /* pop fs */
 551                 {
 552                     WORD seg = *(WORD *)get_stack( context );
 553                     if (INSTR_ReplaceSelector( context, &seg ))
 554                     {
 555                         context->SegFs = seg;
 556                         add_stack(context, long_op ? 4 : 2);
 557                         context->Eip += prefixlen + 2;
 558                         return 0;
 559                     }
 560                 }
 561                 break;
 562             case 0xa9: /* pop gs */
 563                 {
 564                     WORD seg = *(WORD *)get_stack( context );
 565                     if (INSTR_ReplaceSelector( context, &seg ))
 566                     {
 567                         context->SegGs = seg;
 568                         add_stack(context, long_op ? 4 : 2);
 569                         context->Eip += prefixlen + 2;
 570                         return 0;
 571                     }
 572                 }
 573                 break;
 574             case 0xb2: /* lss addr,reg */
 575             case 0xb4: /* lfs addr,reg */
 576             case 0xb5: /* lgs addr,reg */
 577                 if (INSTR_EmulateLDS( context, instr, long_op,
 578                                       long_addr, segprefix, &len ))
 579                 {
 580                     context->Eip += prefixlen + len;
 581                     return 0;
 582                 }
 583                 break;
 584             }
 585             break;  /* Unable to emulate it */
 586
 587         case 0x6c: /* insb     */
 588         case 0x6d: /* insw/d   */
 589         case 0x6e: /* outsb    */
 590         case 0x6f: /* outsw/d  */
 591             {
 592               int typ = *instr;  /* Just in case it's overwritten.  */
 593               int outp = (typ >= 0x6e);
 594               unsigned long count = repX ?
 595                           (long_addr ? context->Ecx : LOWORD(context->Ecx)) : 1;
 596               int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
 597               int step = (context->EFlags & 0x400) ? -opsize : +opsize;
 598               int seg = outp ? context->SegDs : context->SegEs;  /* FIXME: is this right? */
 599
 600               if (outp)
 601                 /* FIXME: Check segment readable.  */
 602                 (void)0;
 603               else
 604                 /* FIXME: Check segment writeable.  */
 605                 (void)0;
 606
 607               if (repX)
 608               {
 609                 if (long_addr) context->Ecx = 0;
 610                 else SET_LOWORD(context->Ecx,0);
 611               }
 612
 613               while (count-- > 0)
 614                 {
 615                   void *data;
 616                   WORD dx = LOWORD(context->Edx);
 617                   if (outp)
 618                   {
 619                       data = make_ptr( context, seg, context->Esi, long_addr );
 620                       if (long_addr) context->Esi += step;
 621                       else ADD_LOWORD(context->Esi,step);
 622                   }
 623                   else
 624                   {
 625                       data = make_ptr( context, seg, context->Edi, long_addr );
 626                       if (long_addr) context->Edi += step;
 627                       else ADD_LOWORD(context->Edi,step);
 628                   }
 629
 630                   switch (typ)
 631                   {
 632                     case 0x6c:
 633                       *(BYTE *)data = INSTR_inport( dx, 1, context );
 634                       break;
 635                     case 0x6d:
 636                       if (long_op)
 637                           *(DWORD *)data = INSTR_inport( dx, 4, context );
 638                       else
 639                           *(WORD *)data = INSTR_inport( dx, 2, context );
 640                       break;
 641                     case 0x6e:
 642                         INSTR_outport( dx, 1, *(BYTE *)data, context );
 643                         break;
 644                     case 0x6f:
 645                         if (long_op)
 646                             INSTR_outport( dx, 4, *(DWORD *)data, context );
 647                         else
 648                             INSTR_outport( dx, 2, *(WORD *)data, context );
 649                         break;
 650                     }
 651                 }
 652               context->Eip += prefixlen + 1;
 653             }
 654             return 0;
 655
 656         case 0x8e: /* mov XX,segment_reg */
 657             {
 658                 WORD seg;
 659                 BYTE *addr = INSTR_GetOperandAddr(context, instr + 1,
 660                                                   long_addr, segprefix, &len );
 661                 if (!addr)
 662                     break;  /* Unable to emulate it */
 663                 seg = *(WORD *)addr;
 664                 if (!INSTR_ReplaceSelector( context, &seg ))
 665                     break;  /* Unable to emulate it */
 666
 667                 switch((instr[1] >> 3) & 7)
 668                 {
 669                 case 0:
 670                     context->SegEs = seg;
 671                     context->Eip += prefixlen + len + 1;
 672                     return 0;
 673                 case 1:  /* cs */
 674                     break;
 675                 case 2:
 676                     context->SegSs = seg;
 677                     context->Eip += prefixlen + len + 1;
 678                     return 0;
 679                 case 3:
 680                     context->SegDs = seg;
 681                     context->Eip += prefixlen + len + 1;
 682                     return 0;
 683                 case 4:
 684                     context->SegFs = seg;
 685                     context->Eip += prefixlen + len + 1;
 686                     return 0;
 687                 case 5:
 688                     context->SegGs = seg;
 689                     context->Eip += prefixlen + len + 1;
 690                     return 0;
 691                 case 6:  /* unused */
 692                 case 7:  /* unused */
 693                     break;
 694                 }
 695             }
 696             break;  /* Unable to emulate it */
 697
 698         case 0xc4: /* les addr,reg */
 699         case 0xc5: /* lds addr,reg */
 700             if (INSTR_EmulateLDS( context, instr, long_op,
 701                                   long_addr, segprefix, &len ))
 702             {
 703                 context->Eip += prefixlen + len;
 704                 return 0;
 705             }
 706             break;  /* Unable to emulate it */
 707
 708         case 0xcd: /* int <XX> */
 709             if (IS_SELECTOR_SYSTEM(context->SegCs))
 710             {
 711                 /* Win32 applications cannot use interrupts */
 712                 ret = EXCEPTION_ACCESS_VIOLATION;
 713                 break;
 714             }
 715             else if (!Dosvm.EmulateInterruptPM && !DPMI_LoadDosSystem())
 716             {
 717                 ERR("could not initialize interrupt handling\n");
 718             }
 719             else
 720             {
 721                 context->Eip += prefixlen + 2;
 722                 Dosvm.EmulateInterruptPM( context, instr[1] );
 723                 return 0;
 724             }
 725             break;  /* Unable to emulate it */
 726
 727         case 0xcf: /* iret */
 728             if (long_op)
 729             {
 730                 DWORD *stack = get_stack( context );
 731                 context->Eip = *stack++;
 732                 context->SegCs  = *stack++;
 733                 context->EFlags = *stack;
 734                 add_stack(context, 3*sizeof(DWORD));  /* Pop the return address and flags */
 735             }
 736             else
 737             {
 738                 WORD *stack = get_stack( context );
 739                 context->Eip = *stack++;
 740                 context->SegCs  = *stack++;
 741                 SET_LOWORD(context->EFlags,*stack);
 742                 add_stack(context, 3*sizeof(WORD));  /* Pop the return address and flags */
 743             }
 744             return 0;
 745
 746         case 0xe4: /* inb al,XX */
 747             SET_LOBYTE(context->Eax,INSTR_inport( instr[1], 1, context ));
 748             context->Eip += prefixlen + 2;
 749             return 0;
 750
 751         case 0xe5: /* in (e)ax,XX */
 752             if (long_op)
 753                 context->Eax = INSTR_inport( instr[1], 4, context );
 754             else
 755                 SET_LOWORD(context->Eax, INSTR_inport( instr[1], 2, context ));
 756             context->Eip += prefixlen + 2;
 757             return 0;
 758
 759         case 0xe6: /* outb XX,al */
 760             INSTR_outport( instr[1], 1, LOBYTE(context->Eax), context );
 761             context->Eip += prefixlen + 2;
 762             return 0;
 763
 764         case 0xe7: /* out XX,(e)ax */
 765             if (long_op)
 766                 INSTR_outport( instr[1], 4, context->Eax, context );
 767             else
 768                 INSTR_outport( instr[1], 2, LOWORD(context->Eax), context );
 769             context->Eip += prefixlen + 2;
 770             return 0;
 771
 772         case 0xec: /* inb al,dx */
 773             SET_LOBYTE(context->Eax, INSTR_inport( LOWORD(context->Edx), 1, context ) );
 774             context->Eip += prefixlen + 1;
 775             return 0;
 776
 777         case 0xed: /* in (e)ax,dx */
 778             if (long_op)
 779                 context->Eax = INSTR_inport( LOWORD(context->Edx), 4, context );
 780             else
 781                 SET_LOWORD(context->Eax, INSTR_inport( LOWORD(context->Edx), 2, context ));
 782             context->Eip += prefixlen + 1;
 783             return 0;
 784
 785         case 0xee: /* outb dx,al */
 786             INSTR_outport( LOWORD(context->Edx), 1, LOBYTE(context->Eax), context );
 787             context->Eip += prefixlen + 1;
 788             return 0;
 789
 790         case 0xef: /* out dx,(e)ax */
 791             if (long_op)
 792                 INSTR_outport( LOWORD(context->Edx), 4, context->Eax, context );
 793             else
 794                 INSTR_outport( LOWORD(context->Edx), 2, LOWORD(context->Eax), context );
 795             context->Eip += prefixlen + 1;
 796             return 0;
 797
 798         case 0xfa: /* cli */
 799             NtCurrentTeb()->dpmi_vif = 0;
 800             context->Eip += prefixlen + 1;
 801             return 0;
 802
 803         case 0xfb: /* sti */
 804             NtCurrentTeb()->dpmi_vif = 1;
 805             context->Eip += prefixlen + 1;
 806             if (NtCurrentTeb()->vm86_pending)
 807             {
 808                 NtCurrentTeb()->vm86_pending = 0;
 809                 return EXCEPTION_VM86_STI;
 810             }
 811             return 0;
 812     }
 813
 814
 815     /* Check for Win16 __GP handler */
 816     if (!IS_SELECTOR_SYSTEM(context->SegCs))
 817     {
 818         SEGPTR gpHandler = HasGPHandler16( MAKESEGPTR( context->SegCs, context->Eip ) );
 819         if (gpHandler)
 820         {
 821             WORD *stack = get_stack( context );
 822             *--stack = context->SegCs;
 823             *--stack = context->Eip;
 824             add_stack(context, -2*sizeof(WORD));
 825
 826             context->SegCs = SELECTOROF( gpHandler );
 827             context->Eip   = OFFSETOF( gpHandler );
 828             return 0;
 829         }
 830     }
 831     return ret;  /* Unable to emulate it */
 832 }
 833
 834 #endif  /* __i386__ */