miscemu/instr.c

   1 /*
   2  * Emulation of priviledged instructions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  */
   6
   7 #include "windows.h"
   8 #include "ldt.h"
   9 #include "global.h"
  10 #include "module.h"
  11 #include "dosexe.h"
  12 #include "miscemu.h"
  13 #include "sig_context.h"
  14 #include "debug.h"
  15
  16
  17 #define IS_V86(context) (EFL_sig(context)&V86_FLAG)
  18 #define IS_SEL_32(context,seg) \
  19    (IS_V86(context) ? FALSE : IS_SELECTOR_32BIT(seg))
  20
  21 #define STACK_sig(context) \
  22    (IS_SEL_32(context,SS_sig(context)) ? ESP_sig(context) : SP_sig(context))
  23
  24 #define MAKE_PTR(seg,off) \
  25    (IS_SELECTOR_SYSTEM(seg) ? (void *)(off) : PTR_SEG_OFF_TO_LIN(seg,off))
  26
  27 #define MK_PTR(context,seg,off) \
  28    (IS_V86(context) ? DOSMEM_MapRealToLinear(MAKELONG(off,seg)) \
  29                     : MAKE_PTR(seg,off))
  30
  31 #define STACK_PTR(context) \
  32    (IS_V86(context) ? DOSMEM_MapRealToLinear(MAKELONG(SP_sig(context),SS_sig(context))) : \
  33     (IS_SELECTOR_SYSTEM(SS_sig(context)) ? (void *)ESP_sig(context) : \
  34      (PTR_SEG_OFF_TO_LIN(SS_sig(context),STACK_sig(context)))))
  35
  36
  37 /***********************************************************************
  38  *           INSTR_ReplaceSelector
  39  *
  40  * Try to replace an invalid selector by a valid one.
  41  * The only selector where it is allowed to do "mov ax,40;mov es,ax"
  42  * is the so called 'bimodal' selector 0x40, which points to the BIOS
  43  * data segment. Used by (at least) Borland products (and programs compiled
  44  * using Borland products).
  45  *
  46  * See Undocumented Windows, Chapter 5, __0040.
  47  */
  48 static WORD INSTR_ReplaceSelector( SIGCONTEXT *context, WORD sel)
  49 {
  50     if (sel == 0x40)
  51     {
  52         static WORD sys_timer = 0;
  53         if (!sys_timer)
  54             sys_timer = CreateSystemTimer( 55, (FARPROC16)DOSMEM_Tick );
  55         return DOSMEM_BiosSeg;
  56     }
  57     return 0;  /* Can't replace selector, crashdump */
  58 }
  59
  60
  61 /***********************************************************************
  62  *           INSTR_GetOperandAddr
  63  *
  64  * Return the address of an instruction operand (from the mod/rm byte).
  65  */
  66 static BYTE *INSTR_GetOperandAddr( SIGCONTEXT *context, BYTE *instr,
  67                                    int long_addr, int segprefix, int *len )
  68 {
  69     int mod, rm, base, index = 0, ss = 0, seg = 0, off;
  70
  71 #define GET_VAL(val,type) \
  72     { *val = *(type *)instr; instr += sizeof(type); *len += sizeof(type); }
  73
  74     *len = 0;
  75     GET_VAL( &mod, BYTE );
  76     rm = mod & 7;
  77     mod >>= 6;
  78
  79     if (mod == 3)
  80     {
  81         switch(rm)
  82         {
  83         case 0: return (BYTE *)&EAX_sig(context);
  84         case 1: return (BYTE *)&ECX_sig(context);
  85         case 2: return (BYTE *)&EDX_sig(context);
  86         case 3: return (BYTE *)&EBX_sig(context);
  87         case 4: return (BYTE *)&ESP_sig(context);
  88         case 5: return (BYTE *)&EBP_sig(context);
  89         case 6: return (BYTE *)&ESI_sig(context);
  90         case 7: return (BYTE *)&EDI_sig(context);
  91         }
  92     }
  93
  94     if (long_addr)
  95     {
  96         if (rm == 4)
  97         {
  98             BYTE sib;
  99             GET_VAL( &sib, BYTE );
 100             rm = sib & 7;
 101             ss = sib >> 6;
 102             switch(sib >> 3)
 103             {
 104             case 0: index = EAX_sig(context); break;
 105             case 1: index = ECX_sig(context); break;
 106             case 2: index = EDX_sig(context); break;
 107             case 3: index = EBX_sig(context); break;
 108             case 4: index = 0; break;
 109             case 5: index = EBP_sig(context); break;
 110             case 6: index = ESI_sig(context); break;
 111             case 7: index = EDI_sig(context); break;
 112             }
 113         }
 114
 115         switch(rm)
 116         {
 117         case 0: base = EAX_sig(context); seg = DS_sig(context); break;
 118         case 1: base = ECX_sig(context); seg = DS_sig(context); break;
 119         case 2: base = EDX_sig(context); seg = DS_sig(context); break;
 120         case 3: base = EBX_sig(context); seg = DS_sig(context); break;
 121         case 4: base = ESP_sig(context); seg = SS_sig(context); break;
 122         case 5: base = EBP_sig(context); seg = SS_sig(context); break;
 123         case 6: base = ESI_sig(context); seg = DS_sig(context); break;
 124         case 7: base = EDI_sig(context); seg = DS_sig(context); break;
 125         }
 126         switch (mod)
 127         {
 128         case 0:
 129             if (rm == 5)  /* special case: ds:(disp32) */
 130             {
 131                 GET_VAL( &base, DWORD );
 132                 seg = DS_sig(context);
 133             }
 134             break;
 135
 136         case 1:  /* 8-bit disp */
 137             GET_VAL( &off, BYTE );
 138             base += (signed char)off;
 139             break;
 140
 141         case 2:  /* 32-bit disp */
 142             GET_VAL( &off, DWORD );
 143             base += (signed long)off;
 144             break;
 145         }
 146     }
 147     else  /* short address */
 148     {
 149         switch(rm)
 150         {
 151         case 0:  /* ds:(bx,si) */
 152             base = BX_sig(context) + SI_sig(context);
 153             seg  = DS_sig(context);
 154             break;
 155         case 1:  /* ds:(bx,di) */
 156             base = BX_sig(context) + DI_sig(context);
 157             seg  = DS_sig(context);
 158             break;
 159         case 2:  /* ss:(bp,si) */
 160             base = BP_sig(context) + SI_sig(context);
 161             seg  = SS_sig(context);
 162             break;
 163         case 3:  /* ss:(bp,di) */
 164             base = BP_sig(context) + DI_sig(context);
 165             seg  = SS_sig(context);
 166             break;
 167         case 4:  /* ds:(si) */
 168             base = SI_sig(context);
 169             seg  = DS_sig(context);
 170             break;
 171         case 5:  /* ds:(di) */
 172             base = DI_sig(context);
 173             seg  = DS_sig(context);
 174             break;
 175         case 6:  /* ss:(bp) */
 176             base = BP_sig(context);
 177             seg  = SS_sig(context);
 178             break;
 179         case 7:  /* ds:(bx) */
 180             base = BX_sig(context);
 181             seg  = DS_sig(context);
 182             break;
 183         }
 184
 185         switch(mod)
 186         {
 187         case 0:
 188             if (rm == 6)  /* special case: ds:(disp16) */
 189             {
 190                 GET_VAL( &base, WORD );
 191                 seg  = DS_sig(context);
 192             }
 193             break;
 194
 195         case 1:  /* 8-bit disp */
 196             GET_VAL( &off, BYTE );
 197             base += (signed char)off;
 198             break;
 199
 200         case 2:  /* 16-bit disp */
 201             GET_VAL( &off, WORD );
 202             base += (signed short)off;
 203             break;
 204         }
 205         base &= 0xffff;
 206     }
 207     if (segprefix != -1) seg = segprefix;
 208
 209     /* Make sure the segment and offset are valid */
 210     if (IS_SELECTOR_SYSTEM(seg)) return (BYTE *)(base + (index << ss));
 211     if (((seg & 7) != 7) || IS_SELECTOR_FREE(seg)) return NULL;
 212     if (GET_SEL_LIMIT(seg) < (base + (index << ss))) return NULL;
 213     return (BYTE *)PTR_SEG_OFF_TO_LIN( seg, (base + (index << ss)) );
 214 #undef GET_VAL
 215 }
 216
 217
 218 /***********************************************************************
 219  *           INSTR_EmulateLDS
 220  *
 221  * Emulate the LDS (and LES,LFS,etc.) instruction.
 222  */
 223 static BOOL32 INSTR_EmulateLDS( SIGCONTEXT *context, BYTE *instr, int long_op,
 224                                 int long_addr, int segprefix, int *len )
 225 {
 226     WORD seg;
 227     BYTE *regmodrm = instr + 1 + (*instr == 0x0f);
 228     BYTE *addr = INSTR_GetOperandAddr( context, regmodrm,
 229                                        long_addr, segprefix, len );
 230     if (!addr)
 231         return FALSE;  /* Unable to emulate it */
 232     seg = *(WORD *)(addr + (long_op ? 4 : 2));
 233
 234     if (!(seg = INSTR_ReplaceSelector( context, seg )))
 235         return FALSE;  /* Unable to emulate it */
 236
 237     /* Now store the offset in the correct register */
 238
 239     switch((*regmodrm >> 3) & 7)
 240     {
 241     case 0:
 242         if (long_op) EAX_sig(context) = *(DWORD *)addr;
 243         else AX_sig(context) = *(WORD *)addr;
 244         break;
 245     case 1:
 246         if (long_op) ECX_sig(context) = *(DWORD *)addr;
 247         else CX_sig(context) = *(WORD *)addr;
 248         break;
 249     case 2:
 250         if (long_op) EDX_sig(context) = *(DWORD *)addr;
 251         else DX_sig(context) = *(WORD *)addr;
 252         break;
 253     case 3:
 254         if (long_op) EBX_sig(context) = *(DWORD *)addr;
 255         else BX_sig(context) = *(WORD *)addr;
 256         break;
 257     case 4:
 258         if (long_op) ESP_sig(context) = *(DWORD *)addr;
 259         else SP_sig(context) = *(WORD *)addr;
 260         break;
 261     case 5:
 262         if (long_op) EBP_sig(context) = *(DWORD *)addr;
 263         else BP_sig(context) = *(WORD *)addr;
 264         break;
 265     case 6:
 266         if (long_op) ESI_sig(context) = *(DWORD *)addr;
 267         else SI_sig(context) = *(WORD *)addr;
 268         break;
 269     case 7:
 270         if (long_op) EDI_sig(context) = *(DWORD *)addr;
 271         else DI_sig(context) = *(WORD *)addr;
 272         break;
 273     }
 274
 275     /* Store the correct segment in the segment register */
 276
 277     switch(*instr)
 278     {
 279     case 0xc4: ES_sig(context) = seg; break;  /* les */
 280     case 0xc5: DS_sig(context) = seg; break;  /* lds */
 281     case 0x0f: switch(instr[1])
 282                {
 283                case 0xb2: SS_sig(context) = seg; break;  /* lss */
 284 #ifdef FS_sig
 285                case 0xb4: FS_sig(context) = seg; break;  /* lfs */
 286 #endif
 287 #ifdef GS_sig
 288                case 0xb5: GS_sig(context) = seg; break;  /* lgs */
 289 #endif
 290                }
 291                break;
 292     }
 293
 294     /* Add the opcode size to the total length */
 295
 296     *len += 1 + (*instr == 0x0f);
 297     return TRUE;
 298 }
 299
 300
 301 /***********************************************************************
 302  *           INSTR_EmulateInstruction
 303  *
 304  * Emulate a priviledged instruction. Returns TRUE if emulation successful.
 305  */
 306 BOOL32 INSTR_EmulateInstruction( SIGCONTEXT *context )
 307 {
 308     int prefix, segprefix, prefixlen, len, repX, long_op, long_addr;
 309     SEGPTR gpHandler;
 310     BYTE *instr;
 311
 312     /* Check for page-fault */
 313
 314 #if defined(TRAP_sig) && defined(CR2_sig)
 315     if (TRAP_sig(context) == 0x0e
 316         && VIRTUAL_HandleFault( (LPVOID)CR2_sig(context) )) return TRUE;
 317 #endif
 318
 319     long_op = long_addr = IS_SEL_32(context,CS_sig(context));
 320     instr = (BYTE *)MK_PTR(context,CS_sig(context),EIP_sig(context));
 321     if (!instr) return FALSE;
 322
 323     /* First handle any possible prefix */
 324
 325     segprefix = -1;  /* no prefix */
 326     prefix = 1;
 327     repX = 0;
 328     prefixlen = 0;
 329     while(prefix)
 330     {
 331         switch(*instr)
 332         {
 333         case 0x2e:
 334             segprefix = CS_sig(context);
 335             break;
 336         case 0x36:
 337             segprefix = SS_sig(context);
 338             break;
 339         case 0x3e:
 340             segprefix = DS_sig(context);
 341             break;
 342         case 0x26:
 343             segprefix = ES_sig(context);
 344             break;
 345 #ifdef FS_sig
 346         case 0x64:
 347             segprefix = FS_sig(context);
 348             break;
 349 #endif
 350 #ifdef GS_sig
 351         case 0x65:
 352             segprefix = GS_sig(context);
 353             break;
 354 #endif
 355         case 0x66:
 356             long_op = !long_op;  /* opcode size prefix */
 357             break;
 358         case 0x67:
 359             long_addr = !long_addr;  /* addr size prefix */
 360             break;
 361         case 0xf0:  /* lock */
 362             break;
 363         case 0xf2:  /* repne */
 364             repX = 1;
 365             break;
 366         case 0xf3:  /* repe */
 367             repX = 2;
 368             break;
 369         default:
 370             prefix = 0;  /* no more prefixes */
 371             break;
 372         }
 373         if (prefix)
 374         {
 375             instr++;
 376             prefixlen++;
 377         }
 378     }
 379
 380     /* Now look at the actual instruction */
 381
 382     switch(*instr)
 383     {
 384         case 0x07: /* pop es */
 385         case 0x17: /* pop ss */
 386         case 0x1f: /* pop ds */
 387             {
 388                 WORD seg = *(WORD *)STACK_PTR( context );
 389                 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 390                 {
 391                     switch(*instr)
 392                     {
 393                     case 0x07: ES_sig(context) = seg; break;
 394                     case 0x17: SS_sig(context) = seg; break;
 395                     case 0x1f: DS_sig(context) = seg; break;
 396                     }
 397                     STACK_sig(context) += long_op ? 4 : 2;
 398                     EIP_sig(context) += prefixlen + 1;
 399                     return TRUE;
 400                 }
 401             }
 402             break;  /* Unable to emulate it */
 403
 404         case 0x0f: /* extended instruction */
 405             switch(instr[1])
 406             {
 407 #ifdef FS_sig
 408             case 0xa1: /* pop fs */
 409                 {
 410                     WORD seg = *(WORD *)STACK_PTR( context );
 411                     if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 412                     {
 413                         FS_sig(context) = seg;
 414                         STACK_sig(context) += long_op ? 4 : 2;
 415                         EIP_sig(context) += prefixlen + 2;
 416                         return TRUE;
 417                     }
 418                 }
 419                 break;
 420 #endif  /* FS_sig */
 421
 422 #ifdef GS_sig
 423             case 0xa9: /* pop gs */
 424                 {
 425                     WORD seg = *(WORD *)STACK_PTR( context );
 426                     if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 427                     {
 428                         GS_sig(context) = seg;
 429                         STACK_sig(context) += long_op ? 4 : 2;
 430                         EIP_sig(context) += prefixlen + 2;
 431                         return TRUE;
 432                     }
 433                 }
 434                 break;
 435 #endif  /* GS_sig */
 436
 437             case 0xb2: /* lss addr,reg */
 438 #ifdef FS_sig
 439             case 0xb4: /* lfs addr,reg */
 440 #endif
 441 #ifdef GS_sig
 442             case 0xb5: /* lgs addr,reg */
 443 #endif
 444                 if (INSTR_EmulateLDS( context, instr, long_op,
 445                                       long_addr, segprefix, &len ))
 446                 {
 447                     EIP_sig(context) += prefixlen + len;
 448                     return TRUE;
 449                 }
 450                 break;
 451             }
 452             break;  /* Unable to emulate it */
 453
 454         case 0x6c: /* insb     */
 455         case 0x6d: /* insw/d   */
 456         case 0x6e: /* outsb    */
 457         case 0x6f: /* outsw/d  */
 458             {
 459               int typ = *instr;  /* Just in case it's overwritten.  */
 460               int outp = (typ >= 0x6e);
 461               unsigned long count = repX ?
 462                           (long_addr ? ECX_sig(context) : CX_sig(context)) : 1;
 463               int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
 464               int step = (EFL_sig(context) & 0x400) ? -opsize : +opsize;
 465               int seg = outp ? DS_sig(context) : ES_sig(context);  /* FIXME: is this right? */
 466
 467               if (outp)
 468                 /* FIXME: Check segment readable.  */
 469                 (void)0;
 470               else
 471                 /* FIXME: Check segment writeable.  */
 472                 (void)0;
 473
 474               if (repX)
 475                 if (long_addr)
 476                   ECX_sig(context) = 0;
 477                 else
 478                   CX_sig(context) = 0;
 479
 480               while (count-- > 0)
 481                 {
 482                   void *data;
 483                   if (outp)
 484                   {
 485                       data = MAKE_PTR(seg,
 486                                long_addr ? ESI_sig(context) : SI_sig(context));
 487                       if (long_addr) ESI_sig(context) += step;
 488                       else SI_sig(context) += step;
 489                   }
 490                   else
 491                   {
 492                       data = MAKE_PTR(seg,
 493                                long_addr ? EDI_sig(context) : DI_sig(context));
 494                       if (long_addr) EDI_sig(context) += step;
 495                       else DI_sig(context) += step;
 496                   }
 497
 498                   switch (typ)
 499                   {
 500                     case 0x6c:
 501                       *((BYTE *)data) = IO_inport( DX_sig(context), 1);
 502                       TRACE(io, "0x%x < %02x @ %04x:%04x\n", DX_sig(context),
 503                         *((BYTE *)data), CS_sig(context), IP_sig(context));
 504                       break;
 505                     case 0x6d:
 506                       if (long_op)
 507                       {
 508                         *((DWORD *)data) = IO_inport( DX_sig(context), 4);
 509                         TRACE(io, "0x%x < %08lx @ %04x:%04x\n", DX_sig(context),
 510                           *((DWORD *)data), CS_sig(context), IP_sig(context));
 511                       }
 512                       else
 513                       {
 514                         *((WORD *)data) = IO_inport( DX_sig(context), 2);
 515                         TRACE(io, "0x%x < %04x @ %04x:%04x\n", DX_sig(context),
 516                           *((WORD *)data), CS_sig(context), IP_sig(context));
 517                       }
 518                       break;
 519                     case 0x6e:
 520                         IO_outport( DX_sig(context), 1, *((BYTE *)data));
 521                         TRACE(io, "0x%x > %02x @ %04x:%04x\n", DX_sig(context),
 522                           *((BYTE *)data), CS_sig(context), IP_sig(context));
 523                         break;
 524                     case 0x6f:
 525                         if (long_op)
 526                         {
 527                             IO_outport( DX_sig(context), 4, *((DWORD *)data));
 528                             TRACE(io, "0x%x > %08lx @ %04x:%04x\n", DX_sig(context),
 529                               *((DWORD *)data), CS_sig(context), IP_sig(context));
 530                         }
 531                         else
 532                         {
 533                             IO_outport( DX_sig(context), 2, *((WORD *)data));
 534                             TRACE(io, "0x%x > %04x @ %04x:%04x\n", DX_sig(context),
 535                               *((WORD *)data), CS_sig(context), IP_sig(context));
 536                         }
 537                         break;
 538                     }
 539                 }
 540               EIP_sig(context) += prefixlen + 1;
 541             }
 542             return TRUE;
 543
 544         case 0x8e: /* mov XX,segment_reg */
 545             {
 546                 WORD seg;
 547                 BYTE *addr = INSTR_GetOperandAddr(context, instr + 1,
 548                                                   long_addr, segprefix, &len );
 549                 if (!addr)
 550                     break;  /* Unable to emulate it */
 551                 seg = *(WORD *)addr;
 552                 if (!(seg = INSTR_ReplaceSelector( context, seg )))
 553                     break;  /* Unable to emulate it */
 554
 555                 switch((instr[1] >> 3) & 7)
 556                 {
 557                 case 0:
 558                     ES_sig(context) = seg;
 559                     EIP_sig(context) += prefixlen + len + 1;
 560                     return TRUE;
 561                 case 1:  /* cs */
 562                     break;
 563                 case 2:
 564                     SS_sig(context) = seg;
 565                     EIP_sig(context) += prefixlen + len + 1;
 566                     return TRUE;
 567                 case 3:
 568                     DS_sig(context) = seg;
 569                     EIP_sig(context) += prefixlen + len + 1;
 570                     return TRUE;
 571                 case 4:
 572 #ifdef FS_sig
 573                     FS_sig(context) = seg;
 574                     EIP_sig(context) += prefixlen + len + 1;
 575                     return TRUE;
 576 #endif
 577                 case 5:
 578 #ifdef GS_sig
 579                     GS_sig(context) = seg;
 580                     EIP_sig(context) += prefixlen + len + 1;
 581                     return TRUE;
 582 #endif
 583                 case 6:  /* unused */
 584                 case 7:  /* unused */
 585                     break;
 586                 }
 587             }
 588             break;  /* Unable to emulate it */
 589
 590         case 0xc4: /* les addr,reg */
 591         case 0xc5: /* lds addr,reg */
 592             if (INSTR_EmulateLDS( context, instr, long_op,
 593                                   long_addr, segprefix, &len ))
 594             {
 595                 EIP_sig(context) += prefixlen + len;
 596                 return TRUE;
 597             }
 598             break;  /* Unable to emulate it */
 599
 600         case 0xcd: /* int <XX> */
 601             if (long_op)
 602             {
 603                 ERR(int, "int xx from 32-bit code is not supported.\n");
 604                 break;  /* Unable to emulate it */
 605             }
 606             else
 607             {
 608                 FARPROC16 addr = INT_GetPMHandler( instr[1] );
 609                 WORD *stack = (WORD *)STACK_PTR( context );
 610                 /* Push the flags and return address on the stack */
 611                 *(--stack) = FL_sig(context);
 612                 *(--stack) = CS_sig(context);
 613                 *(--stack) = IP_sig(context) + prefixlen + 2;
 614                 STACK_sig(context) -= 3 * sizeof(WORD);
 615                 /* Jump to the interrupt handler */
 616                 CS_sig(context)  = HIWORD(addr);
 617                 EIP_sig(context) = LOWORD(addr);
 618             }
 619             return TRUE;
 620
 621         case 0xcf: /* iret */
 622             if (long_op)
 623             {
 624                 DWORD *stack = (DWORD *)STACK_PTR( context );
 625                 EIP_sig(context) = *stack++;
 626                 CS_sig(context)  = *stack++;
 627                 EFL_sig(context) = *stack;
 628                 STACK_sig(context) += 3*sizeof(DWORD);  /* Pop the return address and flags */
 629             }
 630             else
 631             {
 632                 WORD *stack = (WORD *)STACK_PTR( context );
 633                 EIP_sig(context) = *stack++;
 634                 CS_sig(context)  = *stack++;
 635                 FL_sig(context)  = *stack;
 636                 STACK_sig(context) += 3*sizeof(WORD);  /* Pop the return address and flags */
 637             }
 638             return TRUE;
 639
 640         case 0xe4: /* inb al,XX */
 641             AL_sig(context) = IO_inport( instr[1], 1 );
 642             TRACE(io, "0x%x < %02x @ %04x:%04x\n", instr[1],
 643                 AL_sig(context), CS_sig(context), IP_sig(context));
 644             EIP_sig(context) += prefixlen + 2;
 645             return TRUE;
 646
 647         case 0xe5: /* in (e)ax,XX */
 648             if (long_op)
 649             {
 650                 EAX_sig(context) = IO_inport( instr[1], 4 );
 651                 TRACE(io, "0x%x < %08lx @ %04x:%04x\n", instr[1],
 652                     EAX_sig(context), CS_sig(context), IP_sig(context));
 653             }
 654             else
 655             {
 656                 AX_sig(context) = IO_inport( instr[1], 2 );
 657                 TRACE(io, "0x%x < %04x @ %04x:%04x\n", instr[1],
 658                     AX_sig(context), CS_sig(context), IP_sig(context));
 659             }
 660             EIP_sig(context) += prefixlen + 2;
 661             return TRUE;
 662
 663         case 0xe6: /* outb XX,al */
 664             IO_outport( instr[1], 1, AL_sig(context) );
 665             TRACE(io, "0x%x > %02x @ %04x:%04x\n", instr[1],
 666                 AL_sig(context), CS_sig(context), IP_sig(context));
 667             EIP_sig(context) += prefixlen + 2;
 668             return TRUE;
 669
 670         case 0xe7: /* out XX,(e)ax */
 671             if (long_op)
 672             {
 673                 IO_outport( instr[1], 4, EAX_sig(context) );
 674                 TRACE(io, "0x%x > %08lx @ %04x:%04x\n", instr[1],
 675                     EAX_sig(context), CS_sig(context), IP_sig(context));
 676             }
 677             else
 678             {
 679                 IO_outport( instr[1], 2, AX_sig(context) );
 680                 TRACE(io, "0x%x > %04x @ %04x:%04x\n", instr[1],
 681                     AX_sig(context), CS_sig(context), IP_sig(context));
 682             }
 683             EIP_sig(context) += prefixlen + 2;
 684             return TRUE;
 685
 686         case 0xec: /* inb al,dx */
 687             AL_sig(context) = IO_inport( DX_sig(context), 1 );
 688             TRACE(io, "0x%x < %02x @ %04x:%04x\n", DX_sig(context),
 689                 AL_sig(context), CS_sig(context), IP_sig(context));
 690             EIP_sig(context) += prefixlen + 1;
 691             return TRUE;
 692
 693         case 0xed: /* in (e)ax,dx */
 694             if (long_op)
 695             {
 696                 EAX_sig(context) = IO_inport( DX_sig(context), 4 );
 697                 TRACE(io, "0x%x < %08lx @ %04x:%04x\n", DX_sig(context),
 698                     EAX_sig(context), CS_sig(context), IP_sig(context));
 699             }
 700             else
 701             {
 702                 AX_sig(context) = IO_inport( DX_sig(context), 2 );
 703                 TRACE(io, "0x%x < %04x @ %04x:%04x\n", DX_sig(context),
 704                     AX_sig(context), CS_sig(context), IP_sig(context));
 705             }
 706             EIP_sig(context) += prefixlen + 1;
 707             return TRUE;
 708
 709         case 0xee: /* outb dx,al */
 710             IO_outport( DX_sig(context), 1, AL_sig(context) );
 711             TRACE(io, "0x%x > %02x @ %04x:%04x\n", DX_sig(context),
 712                 AL_sig(context), CS_sig(context), IP_sig(context));
 713             EIP_sig(context) += prefixlen + 1;
 714             return TRUE;
 715
 716         case 0xef: /* out dx,(e)ax */
 717             if (long_op)
 718             {
 719                 IO_outport( DX_sig(context), 4, EAX_sig(context) );
 720                 TRACE(io, "0x%x > %08lx @ %04x:%04x\n", DX_sig(context),
 721                     EAX_sig(context), CS_sig(context), IP_sig(context));
 722             }
 723             else
 724             {
 725                 IO_outport( DX_sig(context), 2, AX_sig(context) );
 726                 TRACE(io, "0x%x > %04x @ %04x:%04x\n", DX_sig(context),
 727                     AX_sig(context), CS_sig(context), IP_sig(context));
 728             }
 729             EIP_sig(context) += prefixlen + 1;
 730             return TRUE;
 731
 732         case 0xfa: /* cli, ignored */
 733             EIP_sig(context) += prefixlen + 1;
 734             return TRUE;
 735
 736         case 0xfb: /* sti, ignored */
 737             EIP_sig(context) += prefixlen + 1;
 738             return TRUE;
 739     }
 740
 741
 742     /* Check for Win16 __GP handler */
 743     gpHandler = HasGPHandler( PTR_SEG_OFF_TO_SEGPTR( CS_sig(context),
 744                                                      EIP_sig(context) ) );
 745     if (gpHandler)
 746     {
 747         WORD *stack = (WORD *)STACK_PTR( context );
 748         *--stack = CS_sig(context);
 749         *--stack = EIP_sig(context);
 750         STACK_sig(context) -= 2*sizeof(WORD);
 751
 752         CS_sig(context) = SELECTOROF( gpHandler );
 753         EIP_sig(context) = OFFSETOF( gpHandler );
 754         return TRUE;
 755     }
 756
 757     MSG("Unexpected Windows program segfault"
 758                     " - opcode = %x\n", *instr);
 759     return FALSE;  /* Unable to emulate it */
 760 }