miscemu/instr.c

   1 /*
   2  * Emulation of priviledged instructions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  */
   6
   7 #include "wine/winuser16.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 "selectors.h"
  15 #include "debug.h"
  16
  17
  18 #define IS_V86(context) (EFL_sig(context)&V86_FLAG)
  19 #define IS_SEL_32(context,seg) \
  20    (IS_V86(context) ? FALSE : IS_SELECTOR_32BIT(seg))
  21
  22 #define STACK_sig(context) \
  23    (IS_SEL_32(context,SS_sig(context)) ? ESP_sig(context) : SP_sig(context))
  24
  25 #define MAKE_PTR(seg,off) \
  26    (IS_SELECTOR_SYSTEM(seg) ? (void *)(off) : PTR_SEG_OFF_TO_LIN(seg,off))
  27
  28 #define MK_PTR(context,seg,off) \
  29    (IS_V86(context) ? DOSMEM_MapRealToLinear(MAKELONG(off,seg)) \
  30                     : MAKE_PTR(seg,off))
  31
  32 #define STACK_PTR(context) \
  33    (IS_V86(context) ? DOSMEM_MapRealToLinear(MAKELONG(SP_sig(context),SS_sig(context))) : \
  34     (IS_SELECTOR_SYSTEM(SS_sig(context)) ? (void *)ESP_sig(context) : \
  35      (PTR_SEG_OFF_TO_LIN(SS_sig(context),STACK_sig(context)))))
  36
  37 /* For invalid registers fixup */
  38 extern DWORD CallFrom16_Start,CallFrom16_End;
  39
  40
  41 /***********************************************************************
  42  *           INSTR_ReplaceSelector
  43  *
  44  * Try to replace an invalid selector by a valid one.
  45  * The only selector where it is allowed to do "mov ax,40;mov es,ax"
  46  * is the so called 'bimodal' selector 0x40, which points to the BIOS
  47  * data segment. Used by (at least) Borland products (and programs compiled
  48  * using Borland products).
  49  *
  50  * See Undocumented Windows, Chapter 5, __0040.
  51  */
  52 static BOOL INSTR_ReplaceSelector( SIGCONTEXT *context, WORD *sel )
  53 {
  54     if (IS_SELECTOR_SYSTEM(CS_sig(context)) &&
  55         (EIP_sig(context) >= (DWORD)&CallFrom16_Start) &&
  56         (EIP_sig(context) < (DWORD)&CallFrom16_End))
  57     {
  58         /* Saved selector may have become invalid when the relay code */
  59         /* tries to restore it. We simply clear it. */
  60         *sel = 0;
  61         return TRUE;
  62     }
  63     if (*sel == 0x40)
  64     {
  65         static WORD sys_timer = 0;
  66         if (!sys_timer)
  67             sys_timer = CreateSystemTimer( 55, DOSMEM_Tick );
  68         *sel = DOSMEM_BiosDataSeg;
  69         return TRUE;
  70     }
  71     return FALSE;  /* Can't replace selector, crashdump */
  72 }
  73
  74
  75 /***********************************************************************
  76  *           INSTR_GetOperandAddr
  77  *
  78  * Return the address of an instruction operand (from the mod/rm byte).
  79  */
  80 static BYTE *INSTR_GetOperandAddr( SIGCONTEXT *context, BYTE *instr,
  81                                    int long_addr, int segprefix, int *len )
  82 {
  83     int mod, rm, base, index = 0, ss = 0, seg = 0, off;
  84
  85 #define GET_VAL(val,type) \
  86     { *val = *(type *)instr; instr += sizeof(type); *len += sizeof(type); }
  87
  88     *len = 0;
  89     GET_VAL( &mod, BYTE );
  90     rm = mod & 7;
  91     mod >>= 6;
  92
  93     if (mod == 3)
  94     {
  95         switch(rm)
  96         {
  97         case 0: return (BYTE *)&EAX_sig(context);
  98         case 1: return (BYTE *)&ECX_sig(context);
  99         case 2: return (BYTE *)&EDX_sig(context);
 100         case 3: return (BYTE *)&EBX_sig(context);
 101         case 4: return (BYTE *)&ESP_sig(context);
 102         case 5: return (BYTE *)&EBP_sig(context);
 103         case 6: return (BYTE *)&ESI_sig(context);
 104         case 7: return (BYTE *)&EDI_sig(context);
 105         }
 106     }
 107
 108     if (long_addr)
 109     {
 110         if (rm == 4)
 111         {
 112             BYTE sib;
 113             GET_VAL( &sib, BYTE );
 114             rm = sib & 7;
 115             ss = sib >> 6;
 116             switch(sib >> 3)
 117             {
 118             case 0: index = EAX_sig(context); break;
 119             case 1: index = ECX_sig(context); break;
 120             case 2: index = EDX_sig(context); break;
 121             case 3: index = EBX_sig(context); break;
 122             case 4: index = 0; break;
 123             case 5: index = EBP_sig(context); break;
 124             case 6: index = ESI_sig(context); break;
 125             case 7: index = EDI_sig(context); break;
 126             }
 127         }
 128
 129         switch(rm)
 130         {
 131         case 0: base = EAX_sig(context); seg = DS_sig(context); break;
 132         case 1: base = ECX_sig(context); seg = DS_sig(context); break;
 133         case 2: base = EDX_sig(context); seg = DS_sig(context); break;
 134         case 3: base = EBX_sig(context); seg = DS_sig(context); break;
 135         case 4: base = ESP_sig(context); seg = SS_sig(context); break;
 136         case 5: base = EBP_sig(context); seg = SS_sig(context); break;
 137         case 6: base = ESI_sig(context); seg = DS_sig(context); break;
 138         case 7: base = EDI_sig(context); seg = DS_sig(context); break;
 139         }
 140         switch (mod)
 141         {
 142         case 0:
 143             if (rm == 5)  /* special case: ds:(disp32) */
 144             {
 145                 GET_VAL( &base, DWORD );
 146                 seg = DS_sig(context);
 147             }
 148             break;
 149
 150         case 1:  /* 8-bit disp */
 151             GET_VAL( &off, BYTE );
 152             base += (signed char)off;
 153             break;
 154
 155         case 2:  /* 32-bit disp */
 156             GET_VAL( &off, DWORD );
 157             base += (signed long)off;
 158             break;
 159         }
 160     }
 161     else  /* short address */
 162     {
 163         switch(rm)
 164         {
 165         case 0:  /* ds:(bx,si) */
 166             base = BX_sig(context) + SI_sig(context);
 167             seg  = DS_sig(context);
 168             break;
 169         case 1:  /* ds:(bx,di) */
 170             base = BX_sig(context) + DI_sig(context);
 171             seg  = DS_sig(context);
 172             break;
 173         case 2:  /* ss:(bp,si) */
 174             base = BP_sig(context) + SI_sig(context);
 175             seg  = SS_sig(context);
 176             break;
 177         case 3:  /* ss:(bp,di) */
 178             base = BP_sig(context) + DI_sig(context);
 179             seg  = SS_sig(context);
 180             break;
 181         case 4:  /* ds:(si) */
 182             base = SI_sig(context);
 183             seg  = DS_sig(context);
 184             break;
 185         case 5:  /* ds:(di) */
 186             base = DI_sig(context);
 187             seg  = DS_sig(context);
 188             break;
 189         case 6:  /* ss:(bp) */
 190             base = BP_sig(context);
 191             seg  = SS_sig(context);
 192             break;
 193         case 7:  /* ds:(bx) */
 194             base = BX_sig(context);
 195             seg  = DS_sig(context);
 196             break;
 197         }
 198
 199         switch(mod)
 200         {
 201         case 0:
 202             if (rm == 6)  /* special case: ds:(disp16) */
 203             {
 204                 GET_VAL( &base, WORD );
 205                 seg  = DS_sig(context);
 206             }
 207             break;
 208
 209         case 1:  /* 8-bit disp */
 210             GET_VAL( &off, BYTE );
 211             base += (signed char)off;
 212             break;
 213
 214         case 2:  /* 16-bit disp */
 215             GET_VAL( &off, WORD );
 216             base += (signed short)off;
 217             break;
 218         }
 219         base &= 0xffff;
 220     }
 221     if (segprefix != -1) seg = segprefix;
 222
 223     /* Make sure the segment and offset are valid */
 224     if (IS_SELECTOR_SYSTEM(seg)) return (BYTE *)(base + (index << ss));
 225     if (((seg & 7) != 7) || IS_SELECTOR_FREE(seg)) return NULL;
 226     if (GET_SEL_LIMIT(seg) < (base + (index << ss))) return NULL;
 227     return (BYTE *)PTR_SEG_OFF_TO_LIN( seg, (base + (index << ss)) );
 228 #undef GET_VAL
 229 }
 230
 231
 232 /***********************************************************************
 233  *           INSTR_EmulateLDS
 234  *
 235  * Emulate the LDS (and LES,LFS,etc.) instruction.
 236  */
 237 static BOOL INSTR_EmulateLDS( SIGCONTEXT *context, BYTE *instr, int long_op,
 238                                 int long_addr, int segprefix, int *len )
 239 {
 240     WORD seg;
 241     BYTE *regmodrm = instr + 1 + (*instr == 0x0f);
 242     BYTE *addr = INSTR_GetOperandAddr( context, regmodrm,
 243                                        long_addr, segprefix, len );
 244     if (!addr)
 245         return FALSE;  /* Unable to emulate it */
 246     seg = *(WORD *)(addr + (long_op ? 4 : 2));
 247
 248     if (!INSTR_ReplaceSelector( context, &seg ))
 249         return FALSE;  /* Unable to emulate it */
 250
 251     /* Now store the offset in the correct register */
 252
 253     switch((*regmodrm >> 3) & 7)
 254     {
 255     case 0:
 256         if (long_op) EAX_sig(context) = *(DWORD *)addr;
 257         else AX_sig(context) = *(WORD *)addr;
 258         break;
 259     case 1:
 260         if (long_op) ECX_sig(context) = *(DWORD *)addr;
 261         else CX_sig(context) = *(WORD *)addr;
 262         break;
 263     case 2:
 264         if (long_op) EDX_sig(context) = *(DWORD *)addr;
 265         else DX_sig(context) = *(WORD *)addr;
 266         break;
 267     case 3:
 268         if (long_op) EBX_sig(context) = *(DWORD *)addr;
 269         else BX_sig(context) = *(WORD *)addr;
 270         break;
 271     case 4:
 272         if (long_op) ESP_sig(context) = *(DWORD *)addr;
 273         else SP_sig(context) = *(WORD *)addr;
 274         break;
 275     case 5:
 276         if (long_op) EBP_sig(context) = *(DWORD *)addr;
 277         else BP_sig(context) = *(WORD *)addr;
 278         break;
 279     case 6:
 280         if (long_op) ESI_sig(context) = *(DWORD *)addr;
 281         else SI_sig(context) = *(WORD *)addr;
 282         break;
 283     case 7:
 284         if (long_op) EDI_sig(context) = *(DWORD *)addr;
 285         else DI_sig(context) = *(WORD *)addr;
 286         break;
 287     }
 288
 289     /* Store the correct segment in the segment register */
 290
 291     switch(*instr)
 292     {
 293     case 0xc4: ES_sig(context) = seg; break;  /* les */
 294     case 0xc5: DS_sig(context) = seg; break;  /* lds */
 295     case 0x0f: switch(instr[1])
 296                {
 297                case 0xb2: SS_sig(context) = seg; break;  /* lss */
 298 #ifdef FS_sig
 299                case 0xb4: FS_sig(context) = seg; break;  /* lfs */
 300 #endif
 301 #ifdef GS_sig
 302                case 0xb5: GS_sig(context) = seg; break;  /* lgs */
 303 #endif
 304                }
 305                break;
 306     }
 307
 308     /* Add the opcode size to the total length */
 309
 310     *len += 1 + (*instr == 0x0f);
 311     return TRUE;
 312 }
 313
 314
 315 /***********************************************************************
 316  *           INSTR_EmulateInstruction
 317  *
 318  * Emulate a priviledged instruction. Returns TRUE if emulation successful.
 319  */
 320 BOOL INSTR_EmulateInstruction( SIGCONTEXT *context )
 321 {
 322     int prefix, segprefix, prefixlen, len, repX, long_op, long_addr;
 323     SEGPTR gpHandler;
 324     BYTE *instr;
 325
 326     long_op = long_addr = IS_SEL_32(context,CS_sig(context));
 327     instr = (BYTE *)MK_PTR(context,CS_sig(context),EIP_sig(context));
 328     if (!instr) return FALSE;
 329
 330     /* First handle any possible prefix */
 331
 332     segprefix = -1;  /* no prefix */
 333     prefix = 1;
 334     repX = 0;
 335     prefixlen = 0;
 336     while(prefix)
 337     {
 338         switch(*instr)
 339         {
 340         case 0x2e:
 341             segprefix = CS_sig(context);
 342             break;
 343         case 0x36:
 344             segprefix = SS_sig(context);
 345             break;
 346         case 0x3e:
 347             segprefix = DS_sig(context);
 348             break;
 349         case 0x26:
 350             segprefix = ES_sig(context);
 351             break;
 352 #ifdef FS_sig
 353         case 0x64:
 354             segprefix = FS_sig(context);
 355             break;
 356 #endif
 357 #ifdef GS_sig
 358         case 0x65:
 359             segprefix = GS_sig(context);
 360             break;
 361 #endif
 362         case 0x66:
 363             long_op = !long_op;  /* opcode size prefix */
 364             break;
 365         case 0x67:
 366             long_addr = !long_addr;  /* addr size prefix */
 367             break;
 368         case 0xf0:  /* lock */
 369             break;
 370         case 0xf2:  /* repne */
 371             repX = 1;
 372             break;
 373         case 0xf3:  /* repe */
 374             repX = 2;
 375             break;
 376         default:
 377             prefix = 0;  /* no more prefixes */
 378             break;
 379         }
 380         if (prefix)
 381         {
 382             instr++;
 383             prefixlen++;
 384         }
 385     }
 386
 387     /* Now look at the actual instruction */
 388
 389     switch(*instr)
 390     {
 391         case 0x07: /* pop es */
 392         case 0x17: /* pop ss */
 393         case 0x1f: /* pop ds */
 394             {
 395                 WORD seg = *(WORD *)STACK_PTR( context );
 396                 if (INSTR_ReplaceSelector( context, &seg ))
 397                 {
 398                     switch(*instr)
 399                     {
 400                     case 0x07: ES_sig(context) = seg; break;
 401                     case 0x17: SS_sig(context) = seg; break;
 402                     case 0x1f: DS_sig(context) = seg; break;
 403                     }
 404                     STACK_sig(context) += long_op ? 4 : 2;
 405                     EIP_sig(context) += prefixlen + 1;
 406                     return TRUE;
 407                 }
 408             }
 409             break;  /* Unable to emulate it */
 410
 411         case 0x0f: /* extended instruction */
 412             switch(instr[1])
 413             {
 414             case 0x22: /* mov eax, crX */
 415                 switch (instr[2]) {
 416                 case 0xc0:
 417                         fprintf(stderr,"mov eax,cr0 at 0x%08lx, EAX=0x%08lx\n",
 418                                 EIP_sig(context),EAX_sig(context)
 419                         );
 420                         EIP_sig(context) += prefixlen+3;
 421                         return TRUE;
 422                 default:
 423                         break; /*fallthrough to bad instruction handling */
 424                 }
 425                 break; /*fallthrough to bad instruction handling */
 426             case 0x20: /* mov crX, eax */
 427                 switch (instr[2]) {
 428                 case 0xe0: /* mov cr4, eax */
 429                     /* CR4 register . See linux/arch/i386/mm/init.c, X86_CR4_ defs
 430                      * bit 0: VME       Virtual Mode Exception ?
 431                      * bit 1: PVI       Protected mode Virtual Interrupt
 432                      * bit 2: TSD       Timestamp disable
 433                      * bit 3: DE        Debugging extensions
 434                      * bit 4: PSE       Page size extensions
 435                      * bit 5: PAE   Physical address extension
 436                      * bit 6: MCE       Machine check enable
 437                      * bit 7: PGE   Enable global pages
 438                      * bit 8: PCE       Enable performance counters at IPL3
 439                      */
 440                     fprintf(stderr,"mov cr4,eax at 0x%08lx\n",EIP_sig(context));
 441                     EAX_sig(context) = 0;
 442                     EIP_sig(context) += prefixlen+3;
 443                     return TRUE;
 444                 case 0xc0: /* mov cr0, eax */
 445                     fprintf(stderr,"mov cr0,eax at 0x%08lx\n",EIP_sig(context));
 446                     EAX_sig(context) = 0x10; /* FIXME: set more bits ? */
 447                     EIP_sig(context) += prefixlen+3;
 448                     return TRUE;
 449                 default: /* fallthrough to illegal instruction */
 450                     break;
 451                 }
 452                 /* fallthrough to illegal instruction */
 453                 break;
 454 #ifdef FS_sig
 455             case 0xa1: /* pop fs */
 456                 {
 457                     WORD seg = *(WORD *)STACK_PTR( context );
 458                     if (INSTR_ReplaceSelector( context, &seg ))
 459                     {
 460                         FS_sig(context) = seg;
 461                         STACK_sig(context) += long_op ? 4 : 2;
 462                         EIP_sig(context) += prefixlen + 2;
 463                         return TRUE;
 464                     }
 465                 }
 466                 break;
 467 #endif  /* FS_sig */
 468
 469 #ifdef GS_sig
 470             case 0xa9: /* pop gs */
 471                 {
 472                     WORD seg = *(WORD *)STACK_PTR( context );
 473                     if (INSTR_ReplaceSelector( context, &seg ))
 474                     {
 475                         GS_sig(context) = seg;
 476                         STACK_sig(context) += long_op ? 4 : 2;
 477                         EIP_sig(context) += prefixlen + 2;
 478                         return TRUE;
 479                     }
 480                 }
 481                 break;
 482 #endif  /* GS_sig */
 483
 484             case 0xb2: /* lss addr,reg */
 485 #ifdef FS_sig
 486             case 0xb4: /* lfs addr,reg */
 487 #endif
 488 #ifdef GS_sig
 489             case 0xb5: /* lgs addr,reg */
 490 #endif
 491                 if (INSTR_EmulateLDS( context, instr, long_op,
 492                                       long_addr, segprefix, &len ))
 493                 {
 494                     EIP_sig(context) += prefixlen + len;
 495                     return TRUE;
 496                 }
 497                 break;
 498             }
 499             break;  /* Unable to emulate it */
 500
 501         case 0x6c: /* insb     */
 502         case 0x6d: /* insw/d   */
 503         case 0x6e: /* outsb    */
 504         case 0x6f: /* outsw/d  */
 505             {
 506               int typ = *instr;  /* Just in case it's overwritten.  */
 507               int outp = (typ >= 0x6e);
 508               unsigned long count = repX ?
 509                           (long_addr ? ECX_sig(context) : CX_sig(context)) : 1;
 510               int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
 511               int step = (EFL_sig(context) & 0x400) ? -opsize : +opsize;
 512               int seg = outp ? DS_sig(context) : ES_sig(context);  /* FIXME: is this right? */
 513
 514               if (outp)
 515                 /* FIXME: Check segment readable.  */
 516                 (void)0;
 517               else
 518                 /* FIXME: Check segment writeable.  */
 519                 (void)0;
 520
 521               if (repX)
 522               {
 523                 if (long_addr)
 524                   ECX_sig(context) = 0;
 525                 else
 526                   CX_sig(context) = 0;
 527               }
 528
 529               while (count-- > 0)
 530                 {
 531                   void *data;
 532                   if (outp)
 533                   {
 534                       data = MK_PTR(context, seg,
 535                                long_addr ? ESI_sig(context) : SI_sig(context));
 536                       if (long_addr) ESI_sig(context) += step;
 537                       else SI_sig(context) += step;
 538                   }
 539                   else
 540                   {
 541                       data = MK_PTR(context, seg,
 542                                long_addr ? EDI_sig(context) : DI_sig(context));
 543                       if (long_addr) EDI_sig(context) += step;
 544                       else DI_sig(context) += step;
 545                   }
 546
 547                   switch (typ)
 548                   {
 549                     case 0x6c:
 550                       *((BYTE *)data) = IO_inport( DX_sig(context), 1);
 551                       TRACE(io, "0x%x < %02x @ %04x:%04x\n", DX_sig(context),
 552                         *((BYTE *)data), CS_sig(context), IP_sig(context));
 553                       break;
 554                     case 0x6d:
 555                       if (long_op)
 556                       {
 557                         *((DWORD *)data) = IO_inport( DX_sig(context), 4);
 558                         TRACE(io, "0x%x < %08lx @ %04x:%04x\n", DX_sig(context),
 559                           *((DWORD *)data), CS_sig(context), IP_sig(context));
 560                       }
 561                       else
 562                       {
 563                         *((WORD *)data) = IO_inport( DX_sig(context), 2);
 564                         TRACE(io, "0x%x < %04x @ %04x:%04x\n", DX_sig(context),
 565                           *((WORD *)data), CS_sig(context), IP_sig(context));
 566                       }
 567                       break;
 568                     case 0x6e:
 569                         IO_outport( DX_sig(context), 1, *((BYTE *)data));
 570                         TRACE(io, "0x%x > %02x @ %04x:%04x\n", DX_sig(context),
 571                           *((BYTE *)data), CS_sig(context), IP_sig(context));
 572                         break;
 573                     case 0x6f:
 574                         if (long_op)
 575                         {
 576                             IO_outport( DX_sig(context), 4, *((DWORD *)data));
 577                             TRACE(io, "0x%x > %08lx @ %04x:%04x\n", DX_sig(context),
 578                               *((DWORD *)data), CS_sig(context), IP_sig(context));
 579                         }
 580                         else
 581                         {
 582                             IO_outport( DX_sig(context), 2, *((WORD *)data));
 583                             TRACE(io, "0x%x > %04x @ %04x:%04x\n", DX_sig(context),
 584                               *((WORD *)data), CS_sig(context), IP_sig(context));
 585                         }
 586                         break;
 587                     }
 588                 }
 589               EIP_sig(context) += prefixlen + 1;
 590             }
 591             return TRUE;
 592
 593         case 0x8e: /* mov XX,segment_reg */
 594             {
 595                 WORD seg;
 596                 BYTE *addr = INSTR_GetOperandAddr(context, instr + 1,
 597                                                   long_addr, segprefix, &len );
 598                 if (!addr)
 599                     break;  /* Unable to emulate it */
 600                 seg = *(WORD *)addr;
 601                 if (!INSTR_ReplaceSelector( context, &seg ))
 602                     break;  /* Unable to emulate it */
 603
 604                 switch((instr[1] >> 3) & 7)
 605                 {
 606                 case 0:
 607                     ES_sig(context) = seg;
 608                     EIP_sig(context) += prefixlen + len + 1;
 609                     return TRUE;
 610                 case 1:  /* cs */
 611                     break;
 612                 case 2:
 613                     SS_sig(context) = seg;
 614                     EIP_sig(context) += prefixlen + len + 1;
 615                     return TRUE;
 616                 case 3:
 617                     DS_sig(context) = seg;
 618                     EIP_sig(context) += prefixlen + len + 1;
 619                     return TRUE;
 620                 case 4:
 621 #ifdef FS_sig
 622                     FS_sig(context) = seg;
 623                     EIP_sig(context) += prefixlen + len + 1;
 624                     return TRUE;
 625 #endif
 626                 case 5:
 627 #ifdef GS_sig
 628                     GS_sig(context) = seg;
 629                     EIP_sig(context) += prefixlen + len + 1;
 630                     return TRUE;
 631 #endif
 632                 case 6:  /* unused */
 633                 case 7:  /* unused */
 634                     break;
 635                 }
 636             }
 637             break;  /* Unable to emulate it */
 638
 639         case 0xc4: /* les addr,reg */
 640         case 0xc5: /* lds addr,reg */
 641             if (INSTR_EmulateLDS( context, instr, long_op,
 642                                   long_addr, segprefix, &len ))
 643             {
 644                 EIP_sig(context) += prefixlen + len;
 645                 return TRUE;
 646             }
 647             break;  /* Unable to emulate it */
 648
 649         case 0xcd: /* int <XX> */
 650             if (long_op)
 651             {
 652                 ERR(int, "int xx from 32-bit code is not supported.\n");
 653                 break;  /* Unable to emulate it */
 654             }
 655             else
 656             {
 657                 FARPROC16 addr = INT_GetPMHandler( instr[1] );
 658                 WORD *stack = (WORD *)STACK_PTR( context );
 659                 /* Push the flags and return address on the stack */
 660                 *(--stack) = FL_sig(context);
 661                 *(--stack) = CS_sig(context);
 662                 *(--stack) = IP_sig(context) + prefixlen + 2;
 663                 STACK_sig(context) -= 3 * sizeof(WORD);
 664                 /* Jump to the interrupt handler */
 665                 CS_sig(context)  = HIWORD(addr);
 666                 EIP_sig(context) = LOWORD(addr);
 667             }
 668             return TRUE;
 669
 670         case 0xcf: /* iret */
 671             if (long_op)
 672             {
 673                 DWORD *stack = (DWORD *)STACK_PTR( context );
 674                 EIP_sig(context) = *stack++;
 675                 CS_sig(context)  = *stack++;
 676                 EFL_sig(context) = *stack;
 677                 STACK_sig(context) += 3*sizeof(DWORD);  /* Pop the return address and flags */
 678             }
 679             else
 680             {
 681                 WORD *stack = (WORD *)STACK_PTR( context );
 682                 EIP_sig(context) = *stack++;
 683                 CS_sig(context)  = *stack++;
 684                 FL_sig(context)  = *stack;
 685                 STACK_sig(context) += 3*sizeof(WORD);  /* Pop the return address and flags */
 686             }
 687             return TRUE;
 688
 689         case 0xe4: /* inb al,XX */
 690             AL_sig(context) = IO_inport( instr[1], 1 );
 691             TRACE(io, "0x%x < %02x @ %04x:%04x\n", instr[1],
 692                 AL_sig(context), CS_sig(context), IP_sig(context));
 693             EIP_sig(context) += prefixlen + 2;
 694             return TRUE;
 695
 696         case 0xe5: /* in (e)ax,XX */
 697             if (long_op)
 698             {
 699                 EAX_sig(context) = IO_inport( instr[1], 4 );
 700                 TRACE(io, "0x%x < %08lx @ %04x:%04x\n", instr[1],
 701                     EAX_sig(context), CS_sig(context), IP_sig(context));
 702             }
 703             else
 704             {
 705                 AX_sig(context) = IO_inport( instr[1], 2 );
 706                 TRACE(io, "0x%x < %04x @ %04x:%04x\n", instr[1],
 707                     AX_sig(context), CS_sig(context), IP_sig(context));
 708             }
 709             EIP_sig(context) += prefixlen + 2;
 710             return TRUE;
 711
 712         case 0xe6: /* outb XX,al */
 713             IO_outport( instr[1], 1, AL_sig(context) );
 714             TRACE(io, "0x%x > %02x @ %04x:%04x\n", instr[1],
 715                 AL_sig(context), CS_sig(context), IP_sig(context));
 716             EIP_sig(context) += prefixlen + 2;
 717             return TRUE;
 718
 719         case 0xe7: /* out XX,(e)ax */
 720             if (long_op)
 721             {
 722                 IO_outport( instr[1], 4, EAX_sig(context) );
 723                 TRACE(io, "0x%x > %08lx @ %04x:%04x\n", instr[1],
 724                     EAX_sig(context), CS_sig(context), IP_sig(context));
 725             }
 726             else
 727             {
 728                 IO_outport( instr[1], 2, AX_sig(context) );
 729                 TRACE(io, "0x%x > %04x @ %04x:%04x\n", instr[1],
 730                     AX_sig(context), CS_sig(context), IP_sig(context));
 731             }
 732             EIP_sig(context) += prefixlen + 2;
 733             return TRUE;
 734
 735         case 0xec: /* inb al,dx */
 736             AL_sig(context) = IO_inport( DX_sig(context), 1 );
 737             TRACE(io, "0x%x < %02x @ %04x:%04x\n", DX_sig(context),
 738                 AL_sig(context), CS_sig(context), IP_sig(context));
 739             EIP_sig(context) += prefixlen + 1;
 740             return TRUE;
 741
 742         case 0xed: /* in (e)ax,dx */
 743             if (long_op)
 744             {
 745                 EAX_sig(context) = IO_inport( DX_sig(context), 4 );
 746                 TRACE(io, "0x%x < %08lx @ %04x:%04x\n", DX_sig(context),
 747                     EAX_sig(context), CS_sig(context), IP_sig(context));
 748             }
 749             else
 750             {
 751                 AX_sig(context) = IO_inport( DX_sig(context), 2 );
 752                 TRACE(io, "0x%x < %04x @ %04x:%04x\n", DX_sig(context),
 753                     AX_sig(context), CS_sig(context), IP_sig(context));
 754             }
 755             EIP_sig(context) += prefixlen + 1;
 756             return TRUE;
 757
 758         case 0xee: /* outb dx,al */
 759             IO_outport( DX_sig(context), 1, AL_sig(context) );
 760             TRACE(io, "0x%x > %02x @ %04x:%04x\n", DX_sig(context),
 761                 AL_sig(context), CS_sig(context), IP_sig(context));
 762             EIP_sig(context) += prefixlen + 1;
 763             return TRUE;
 764
 765         case 0xef: /* out dx,(e)ax */
 766             if (long_op)
 767             {
 768                 IO_outport( DX_sig(context), 4, EAX_sig(context) );
 769                 TRACE(io, "0x%x > %08lx @ %04x:%04x\n", DX_sig(context),
 770                     EAX_sig(context), CS_sig(context), IP_sig(context));
 771             }
 772             else
 773             {
 774                 IO_outport( DX_sig(context), 2, AX_sig(context) );
 775                 TRACE(io, "0x%x > %04x @ %04x:%04x\n", DX_sig(context),
 776                     AX_sig(context), CS_sig(context), IP_sig(context));
 777             }
 778             EIP_sig(context) += prefixlen + 1;
 779             return TRUE;
 780
 781         case 0xfa: /* cli, ignored */
 782             EIP_sig(context) += prefixlen + 1;
 783             return TRUE;
 784
 785         case 0xfb: /* sti, ignored */
 786             EIP_sig(context) += prefixlen + 1;
 787             return TRUE;
 788     }
 789
 790
 791     /* Check for Win16 __GP handler */
 792     gpHandler = HasGPHandler16( PTR_SEG_OFF_TO_SEGPTR( CS_sig(context),
 793                                                      EIP_sig(context) ) );
 794     if (gpHandler)
 795     {
 796         WORD *stack = (WORD *)STACK_PTR( context );
 797         *--stack = CS_sig(context);
 798         *--stack = EIP_sig(context);
 799         STACK_sig(context) -= 2*sizeof(WORD);
 800
 801         CS_sig(context) = SELECTOROF( gpHandler );
 802         EIP_sig(context) = OFFSETOF( gpHandler );
 803         return TRUE;
 804     }
 805
 806     MSG("Unexpected Windows program segfault"
 807                     " - opcode = %x\n", *instr);
 808     return FALSE;  /* Unable to emulate it */
 809 }