memory/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 "selectors.h"
  14 #include "debugtools.h"
  15
  16 DECLARE_DEBUG_CHANNEL(int)
  17 DECLARE_DEBUG_CHANNEL(io)
  18
  19 #ifdef __i386__
  20
  21 #define IS_SEL_32(context,seg) \
  22    (ISV86(context) ? FALSE : IS_SELECTOR_32BIT(seg))
  23
  24 #define STACK_reg(context) \
  25    (IS_SEL_32(context,SS_reg(context)) ? ESP_reg(context) : (DWORD)LOWORD(ESP_reg(context)))
  26
  27 #define ADD_STACK_reg(context,offset) \
  28    do { if (IS_SEL_32(context,SS_reg(context))) ESP_reg(context) += (offset); \
  29         else ADD_LOWORD(ESP_reg(context),(offset)); } while(0)
  30
  31 #define MAKE_PTR(seg,off) \
  32    (IS_SELECTOR_SYSTEM(seg) ? (void *)(off) : PTR_SEG_OFF_TO_LIN(seg,off))
  33
  34 #define MK_PTR(context,seg,off) \
  35    (ISV86(context) ? DOSMEM_MapRealToLinear(MAKELONG(off,seg)) \
  36                    : MAKE_PTR(seg,off))
  37
  38 #define STACK_PTR(context) \
  39    (ISV86(context) ? \
  40     DOSMEM_MapRealToLinear(MAKELONG(LOWORD(ESP_reg(context)),SS_reg(context))) : \
  41     (IS_SELECTOR_SYSTEM(SS_reg(context)) ? (void *)ESP_reg(context) : \
  42      (PTR_SEG_OFF_TO_LIN(SS_reg(context),STACK_reg(context)))))
  43
  44 /***********************************************************************
  45  *           INSTR_ReplaceSelector
  46  *
  47  * Try to replace an invalid selector by a valid one.
  48  * The only selector where it is allowed to do "mov ax,40;mov es,ax"
  49  * is the so called 'bimodal' selector 0x40, which points to the BIOS
  50  * data segment. Used by (at least) Borland products (and programs compiled
  51  * using Borland products).
  52  *
  53  * See Undocumented Windows, Chapter 5, __0040.
  54  */
  55 static BOOL INSTR_ReplaceSelector( CONTEXT86 *context, WORD *sel )
  56 {
  57     extern char Call16_Start, Call16_End;
  58
  59     if (IS_SELECTOR_SYSTEM(CS_reg(context)))
  60         if (    (char *)EIP_reg(context) >= &Call16_Start
  61              && (char *)EIP_reg(context) <  &Call16_End   )
  62         {
  63             /* Saved selector may have become invalid when the relay code */
  64             /* tries to restore it. We simply clear it. */
  65             *sel = 0;
  66             return TRUE;
  67         }
  68
  69     if (*sel == 0x40)
  70     {
  71         static WORD sys_timer = 0;
  72         if (!sys_timer)
  73             sys_timer = CreateSystemTimer( 55, DOSMEM_Tick );
  74         *sel = DOSMEM_BiosDataSeg;
  75         return TRUE;
  76     }
  77     if (!IS_SELECTOR_SYSTEM(*sel) && !IS_SELECTOR_FREE(*sel))
  78         ERR_(int)("Got protection fault on valid selector, maybe your kernel is too old?\n" );
  79     return FALSE;  /* Can't replace selector, crashdump */
  80 }
  81
  82
  83 /***********************************************************************
  84  *           INSTR_GetOperandAddr
  85  *
  86  * Return the address of an instruction operand (from the mod/rm byte).
  87  */
  88 static BYTE *INSTR_GetOperandAddr( CONTEXT86 *context, BYTE *instr,
  89                                    int long_addr, int segprefix, int *len )
  90 {
  91     int mod, rm, base, index = 0, ss = 0, seg = 0, off;
  92
  93 #define GET_VAL(val,type) \
  94     { *val = *(type *)instr; instr += sizeof(type); *len += sizeof(type); }
  95
  96     *len = 0;
  97     GET_VAL( &mod, BYTE );
  98     rm = mod & 7;
  99     mod >>= 6;
 100
 101     if (mod == 3)
 102     {
 103         switch(rm)
 104         {
 105         case 0: return (BYTE *)&EAX_reg(context);
 106         case 1: return (BYTE *)&ECX_reg(context);
 107         case 2: return (BYTE *)&EDX_reg(context);
 108         case 3: return (BYTE *)&EBX_reg(context);
 109         case 4: return (BYTE *)&ESP_reg(context);
 110         case 5: return (BYTE *)&EBP_reg(context);
 111         case 6: return (BYTE *)&ESI_reg(context);
 112         case 7: return (BYTE *)&EDI_reg(context);
 113         }
 114     }
 115
 116     if (long_addr)
 117     {
 118         if (rm == 4)
 119         {
 120             BYTE sib;
 121             GET_VAL( &sib, BYTE );
 122             rm = sib & 7;
 123             ss = sib >> 6;
 124             switch(sib >> 3)
 125             {
 126             case 0: index = EAX_reg(context); break;
 127             case 1: index = ECX_reg(context); break;
 128             case 2: index = EDX_reg(context); break;
 129             case 3: index = EBX_reg(context); break;
 130             case 4: index = 0; break;
 131             case 5: index = EBP_reg(context); break;
 132             case 6: index = ESI_reg(context); break;
 133             case 7: index = EDI_reg(context); break;
 134             }
 135         }
 136
 137         switch(rm)
 138         {
 139         case 0: base = EAX_reg(context); seg = DS_reg(context); break;
 140         case 1: base = ECX_reg(context); seg = DS_reg(context); break;
 141         case 2: base = EDX_reg(context); seg = DS_reg(context); break;
 142         case 3: base = EBX_reg(context); seg = DS_reg(context); break;
 143         case 4: base = ESP_reg(context); seg = SS_reg(context); break;
 144         case 5: base = EBP_reg(context); seg = SS_reg(context); break;
 145         case 6: base = ESI_reg(context); seg = DS_reg(context); break;
 146         case 7: base = EDI_reg(context); seg = DS_reg(context); break;
 147         }
 148         switch (mod)
 149         {
 150         case 0:
 151             if (rm == 5)  /* special case: ds:(disp32) */
 152             {
 153                 GET_VAL( &base, DWORD );
 154                 seg = DS_reg(context);
 155             }
 156             break;
 157
 158         case 1:  /* 8-bit disp */
 159             GET_VAL( &off, BYTE );
 160             base += (signed char)off;
 161             break;
 162
 163         case 2:  /* 32-bit disp */
 164             GET_VAL( &off, DWORD );
 165             base += (signed long)off;
 166             break;
 167         }
 168     }
 169     else  /* short address */
 170     {
 171         switch(rm)
 172         {
 173         case 0:  /* ds:(bx,si) */
 174             base = LOWORD(EBX_reg(context)) + LOWORD(ESI_reg(context));
 175             seg  = DS_reg(context);
 176             break;
 177         case 1:  /* ds:(bx,di) */
 178             base = LOWORD(EBX_reg(context)) + LOWORD(EDI_reg(context));
 179             seg  = DS_reg(context);
 180             break;
 181         case 2:  /* ss:(bp,si) */
 182             base = LOWORD(EBP_reg(context)) + LOWORD(ESI_reg(context));
 183             seg  = SS_reg(context);
 184             break;
 185         case 3:  /* ss:(bp,di) */
 186             base = LOWORD(EBP_reg(context)) + LOWORD(EDI_reg(context));
 187             seg  = SS_reg(context);
 188             break;
 189         case 4:  /* ds:(si) */
 190             base = LOWORD(ESI_reg(context));
 191             seg  = DS_reg(context);
 192             break;
 193         case 5:  /* ds:(di) */
 194             base = LOWORD(EDI_reg(context));
 195             seg  = DS_reg(context);
 196             break;
 197         case 6:  /* ss:(bp) */
 198             base = LOWORD(EBP_reg(context));
 199             seg  = SS_reg(context);
 200             break;
 201         case 7:  /* ds:(bx) */
 202             base = LOWORD(EBX_reg(context));
 203             seg  = DS_reg(context);
 204             break;
 205         }
 206
 207         switch(mod)
 208         {
 209         case 0:
 210             if (rm == 6)  /* special case: ds:(disp16) */
 211             {
 212                 GET_VAL( &base, WORD );
 213                 seg  = DS_reg(context);
 214             }
 215             break;
 216
 217         case 1:  /* 8-bit disp */
 218             GET_VAL( &off, BYTE );
 219             base += (signed char)off;
 220             break;
 221
 222         case 2:  /* 16-bit disp */
 223             GET_VAL( &off, WORD );
 224             base += (signed short)off;
 225             break;
 226         }
 227         base &= 0xffff;
 228     }
 229     if (segprefix != -1) seg = segprefix;
 230
 231     /* Make sure the segment and offset are valid */
 232     if (IS_SELECTOR_SYSTEM(seg)) return (BYTE *)(base + (index << ss));
 233     if (((seg & 7) != 7) || IS_SELECTOR_FREE(seg)) return NULL;
 234     if (GET_SEL_LIMIT(seg) < (base + (index << ss))) return NULL;
 235     return (BYTE *)PTR_SEG_OFF_TO_LIN( seg, (base + (index << ss)) );
 236 #undef GET_VAL
 237 }
 238
 239
 240 /***********************************************************************
 241  *           INSTR_EmulateLDS
 242  *
 243  * Emulate the LDS (and LES,LFS,etc.) instruction.
 244  */
 245 static BOOL INSTR_EmulateLDS( CONTEXT86 *context, BYTE *instr, int long_op,
 246                               int long_addr, int segprefix, int *len )
 247 {
 248     WORD seg;
 249     BYTE *regmodrm = instr + 1 + (*instr == 0x0f);
 250     BYTE *addr = INSTR_GetOperandAddr( context, regmodrm,
 251                                        long_addr, segprefix, len );
 252     if (!addr)
 253         return FALSE;  /* Unable to emulate it */
 254     seg = *(WORD *)(addr + (long_op ? 4 : 2));
 255
 256     if (!INSTR_ReplaceSelector( context, &seg ))
 257         return FALSE;  /* Unable to emulate it */
 258
 259     /* Now store the offset in the correct register */
 260
 261     switch((*regmodrm >> 3) & 7)
 262     {
 263     case 0:
 264         if (long_op) EAX_reg(context) = *(DWORD *)addr;
 265         else SET_LOWORD(EAX_reg(context),*(WORD *)addr);
 266         break;
 267     case 1:
 268         if (long_op) ECX_reg(context) = *(DWORD *)addr;
 269         else SET_LOWORD(ECX_reg(context),*(WORD *)addr);
 270         break;
 271     case 2:
 272         if (long_op) EDX_reg(context) = *(DWORD *)addr;
 273         else SET_LOWORD(EDX_reg(context),*(WORD *)addr);
 274         break;
 275     case 3:
 276         if (long_op) EBX_reg(context) = *(DWORD *)addr;
 277         else SET_LOWORD(EBX_reg(context),*(WORD *)addr);
 278         break;
 279     case 4:
 280         if (long_op) ESP_reg(context) = *(DWORD *)addr;
 281         else SET_LOWORD(ESP_reg(context),*(WORD *)addr);
 282         break;
 283     case 5:
 284         if (long_op) EBP_reg(context) = *(DWORD *)addr;
 285         else SET_LOWORD(EBP_reg(context),*(WORD *)addr);
 286         break;
 287     case 6:
 288         if (long_op) ESI_reg(context) = *(DWORD *)addr;
 289         else SET_LOWORD(ESI_reg(context),*(WORD *)addr);
 290         break;
 291     case 7:
 292         if (long_op) EDI_reg(context) = *(DWORD *)addr;
 293         else SET_LOWORD(EDI_reg(context),*(WORD *)addr);
 294         break;
 295     }
 296
 297     /* Store the correct segment in the segment register */
 298
 299     switch(*instr)
 300     {
 301     case 0xc4: ES_reg(context) = seg; break;  /* les */
 302     case 0xc5: DS_reg(context) = seg; break;  /* lds */
 303     case 0x0f: switch(instr[1])
 304                {
 305                case 0xb2: SS_reg(context) = seg; break;  /* lss */
 306                case 0xb4: FS_reg(context) = seg; break;  /* lfs */
 307                case 0xb5: GS_reg(context) = seg; break;  /* lgs */
 308                }
 309                break;
 310     }
 311
 312     /* Add the opcode size to the total length */
 313
 314     *len += 1 + (*instr == 0x0f);
 315     return TRUE;
 316 }
 317
 318 /***********************************************************************
 319  *           INSTR_inport
 320  *
 321  * input on a I/O port
 322  */
 323 static DWORD INSTR_inport( WORD port, int size, CONTEXT86 *context )
 324 {
 325     DWORD res = IO_inport( port, size );
 326     if (TRACE_ON(io))
 327     {
 328         switch(size)
 329         {
 330         case 1:
 331             DPRINTF( "0x%x < %02x @ %04x:%04x\n", port, LOBYTE(res),
 332                      (WORD)CS_reg(context), LOWORD(EIP_reg(context)));
 333             break;
 334         case 2:
 335             DPRINTF( "0x%x < %04x @ %04x:%04x\n", port, LOWORD(res),
 336                      (WORD)CS_reg(context), LOWORD(EIP_reg(context)));
 337             break;
 338         case 4:
 339             DPRINTF( "0x%x < %08lx @ %04x:%04x\n", port, res,
 340                      (WORD)CS_reg(context), LOWORD(EIP_reg(context)));
 341             break;
 342         }
 343     }
 344     return res;
 345 }
 346
 347
 348 /***********************************************************************
 349  *           INSTR_outport
 350  *
 351  * output on a I/O port
 352  */
 353 static void INSTR_outport( WORD port, int size, DWORD val, CONTEXT86 *context )
 354 {
 355     IO_outport( port, size, val );
 356     if (TRACE_ON(io))
 357     {
 358         switch(size)
 359         {
 360         case 1:
 361             DPRINTF("0x%x > %02x @ %04x:%04x\n", port, LOBYTE(val),
 362                     (WORD)CS_reg(context), LOWORD(EIP_reg(context)));
 363             break;
 364         case 2:
 365             DPRINTF("0x%x > %04x @ %04x:%04x\n", port, LOWORD(val),
 366                     (WORD)CS_reg(context), LOWORD(EIP_reg(context)));
 367             break;
 368         case 4:
 369             DPRINTF("0x%x > %08lx @ %04x:%04x\n", port, val,
 370                     (WORD)CS_reg(context), LOWORD(EIP_reg(context)));
 371             break;
 372         }
 373     }
 374 }
 375
 376
 377 /***********************************************************************
 378  *           INSTR_EmulateInstruction
 379  *
 380  * Emulate a priviledged instruction. Returns TRUE if emulation successful.
 381  */
 382 BOOL INSTR_EmulateInstruction( CONTEXT86 *context )
 383 {
 384     int prefix, segprefix, prefixlen, len, repX, long_op, long_addr;
 385     SEGPTR gpHandler;
 386     BYTE *instr;
 387
 388     long_op = long_addr = IS_SEL_32(context,CS_reg(context));
 389     instr = (BYTE *)MK_PTR(context,CS_reg(context),EIP_reg(context));
 390     if (!instr) return FALSE;
 391
 392     /* First handle any possible prefix */
 393
 394     segprefix = -1;  /* no prefix */
 395     prefix = 1;
 396     repX = 0;
 397     prefixlen = 0;
 398     while(prefix)
 399     {
 400         switch(*instr)
 401         {
 402         case 0x2e:
 403             segprefix = CS_reg(context);
 404             break;
 405         case 0x36:
 406             segprefix = SS_reg(context);
 407             break;
 408         case 0x3e:
 409             segprefix = DS_reg(context);
 410             break;
 411         case 0x26:
 412             segprefix = ES_reg(context);
 413             break;
 414         case 0x64:
 415             segprefix = FS_reg(context);
 416             break;
 417         case 0x65:
 418             segprefix = GS_reg(context);
 419             break;
 420         case 0x66:
 421             long_op = !long_op;  /* opcode size prefix */
 422             break;
 423         case 0x67:
 424             long_addr = !long_addr;  /* addr size prefix */
 425             break;
 426         case 0xf0:  /* lock */
 427             break;
 428         case 0xf2:  /* repne */
 429             repX = 1;
 430             break;
 431         case 0xf3:  /* repe */
 432             repX = 2;
 433             break;
 434         default:
 435             prefix = 0;  /* no more prefixes */
 436             break;
 437         }
 438         if (prefix)
 439         {
 440             instr++;
 441             prefixlen++;
 442         }
 443     }
 444
 445     /* Now look at the actual instruction */
 446
 447     switch(*instr)
 448     {
 449         case 0x07: /* pop es */
 450         case 0x17: /* pop ss */
 451         case 0x1f: /* pop ds */
 452             {
 453                 WORD seg = *(WORD *)STACK_PTR( context );
 454                 if (INSTR_ReplaceSelector( context, &seg ))
 455                 {
 456                     switch(*instr)
 457                     {
 458                     case 0x07: ES_reg(context) = seg; break;
 459                     case 0x17: SS_reg(context) = seg; break;
 460                     case 0x1f: DS_reg(context) = seg; break;
 461                     }
 462                     ADD_STACK_reg(context, long_op ? 4 : 2);
 463                     EIP_reg(context) += prefixlen + 1;
 464                     return TRUE;
 465                 }
 466             }
 467             break;  /* Unable to emulate it */
 468
 469         case 0x0f: /* extended instruction */
 470             switch(instr[1])
 471             {
 472             case 0x22: /* mov eax, crX */
 473                 switch (instr[2]) {
 474                 case 0xc0:
 475                         fprintf(stderr,"mov eax,cr0 at 0x%08lx, EAX=0x%08lx\n",
 476                                 EIP_reg(context),EAX_reg(context)
 477                         );
 478                         EIP_reg(context) += prefixlen+3;
 479                         return TRUE;
 480                 default:
 481                         break; /*fallthrough to bad instruction handling */
 482                 }
 483                 break; /*fallthrough to bad instruction handling */
 484             case 0x20: /* mov crX, eax */
 485                 switch (instr[2]) {
 486                 case 0xe0: /* mov cr4, eax */
 487                     /* CR4 register . See linux/arch/i386/mm/init.c, X86_CR4_ defs
 488                      * bit 0: VME       Virtual Mode Exception ?
 489                      * bit 1: PVI       Protected mode Virtual Interrupt
 490                      * bit 2: TSD       Timestamp disable
 491                      * bit 3: DE        Debugging extensions
 492                      * bit 4: PSE       Page size extensions
 493                      * bit 5: PAE   Physical address extension
 494                      * bit 6: MCE       Machine check enable
 495                      * bit 7: PGE   Enable global pages
 496                      * bit 8: PCE       Enable performance counters at IPL3
 497                      */
 498                     fprintf(stderr,"mov cr4,eax at 0x%08lx\n",EIP_reg(context));
 499                     EAX_reg(context) = 0;
 500                     EIP_reg(context) += prefixlen+3;
 501                     return TRUE;
 502                 case 0xc0: /* mov cr0, eax */
 503                     fprintf(stderr,"mov cr0,eax at 0x%08lx\n",EIP_reg(context));
 504                     EAX_reg(context) = 0x10; /* FIXME: set more bits ? */
 505                     EIP_reg(context) += prefixlen+3;
 506                     return TRUE;
 507                 default: /* fallthrough to illegal instruction */
 508                     break;
 509                 }
 510                 /* fallthrough to illegal instruction */
 511                 break;
 512             case 0xa1: /* pop fs */
 513                 {
 514                     WORD seg = *(WORD *)STACK_PTR( context );
 515                     if (INSTR_ReplaceSelector( context, &seg ))
 516                     {
 517                         FS_reg(context) = seg;
 518                         ADD_STACK_reg(context, long_op ? 4 : 2);
 519                         EIP_reg(context) += prefixlen + 2;
 520                         return TRUE;
 521                     }
 522                 }
 523                 break;
 524             case 0xa9: /* pop gs */
 525                 {
 526                     WORD seg = *(WORD *)STACK_PTR( context );
 527                     if (INSTR_ReplaceSelector( context, &seg ))
 528                     {
 529                         GS_reg(context) = seg;
 530                         ADD_STACK_reg(context, long_op ? 4 : 2);
 531                         EIP_reg(context) += prefixlen + 2;
 532                         return TRUE;
 533                     }
 534                 }
 535                 break;
 536             case 0xb2: /* lss addr,reg */
 537             case 0xb4: /* lfs addr,reg */
 538             case 0xb5: /* lgs addr,reg */
 539                 if (INSTR_EmulateLDS( context, instr, long_op,
 540                                       long_addr, segprefix, &len ))
 541                 {
 542                     EIP_reg(context) += prefixlen + len;
 543                     return TRUE;
 544                 }
 545                 break;
 546             }
 547             break;  /* Unable to emulate it */
 548
 549         case 0x6c: /* insb     */
 550         case 0x6d: /* insw/d   */
 551         case 0x6e: /* outsb    */
 552         case 0x6f: /* outsw/d  */
 553             {
 554               int typ = *instr;  /* Just in case it's overwritten.  */
 555               int outp = (typ >= 0x6e);
 556               unsigned long count = repX ?
 557                           (long_addr ? ECX_reg(context) : LOWORD(ECX_reg(context))) : 1;
 558               int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
 559               int step = (EFL_reg(context) & 0x400) ? -opsize : +opsize;
 560               int seg = outp ? DS_reg(context) : ES_reg(context);  /* FIXME: is this right? */
 561
 562               if (outp)
 563                 /* FIXME: Check segment readable.  */
 564                 (void)0;
 565               else
 566                 /* FIXME: Check segment writeable.  */
 567                 (void)0;
 568
 569               if (repX)
 570               {
 571                 if (long_addr) ECX_reg(context) = 0;
 572                 else SET_LOWORD(ECX_reg(context),0);
 573               }
 574
 575               while (count-- > 0)
 576                 {
 577                   void *data;
 578                   WORD dx = LOWORD(EDX_reg(context));
 579                   if (outp)
 580                   {
 581                       data = MK_PTR(context, seg,
 582                                     long_addr ? ESI_reg(context) : LOWORD(ESI_reg(context)));
 583                       if (long_addr) ESI_reg(context) += step;
 584                       else ADD_LOWORD(ESI_reg(context),step);
 585                   }
 586                   else
 587                   {
 588                       data = MK_PTR(context, seg,
 589                                     long_addr ? EDI_reg(context) : LOWORD(EDI_reg(context)));
 590                       if (long_addr) EDI_reg(context) += step;
 591                       else ADD_LOWORD(EDI_reg(context),step);
 592                   }
 593
 594                   switch (typ)
 595                   {
 596                     case 0x6c:
 597                       *(BYTE *)data = INSTR_inport( dx, 1, context );
 598                       break;
 599                     case 0x6d:
 600                       if (long_op)
 601                           *(DWORD *)data = INSTR_inport( dx, 4, context );
 602                       else
 603                           *(WORD *)data = INSTR_inport( dx, 2, context );
 604                       break;
 605                     case 0x6e:
 606                         INSTR_outport( dx, 1, *(BYTE *)data, context );
 607                         break;
 608                     case 0x6f:
 609                         if (long_op)
 610                             INSTR_outport( dx, 4, *(DWORD *)data, context );
 611                         else
 612                             INSTR_outport( dx, 2, *(WORD *)data, context );
 613                         break;
 614                     }
 615                 }
 616               EIP_reg(context) += prefixlen + 1;
 617             }
 618             return TRUE;
 619
 620         case 0x8e: /* mov XX,segment_reg */
 621             {
 622                 WORD seg;
 623                 BYTE *addr = INSTR_GetOperandAddr(context, instr + 1,
 624                                                   long_addr, segprefix, &len );
 625                 if (!addr)
 626                     break;  /* Unable to emulate it */
 627                 seg = *(WORD *)addr;
 628                 if (!INSTR_ReplaceSelector( context, &seg ))
 629                     break;  /* Unable to emulate it */
 630
 631                 switch((instr[1] >> 3) & 7)
 632                 {
 633                 case 0:
 634                     ES_reg(context) = seg;
 635                     EIP_reg(context) += prefixlen + len + 1;
 636                     return TRUE;
 637                 case 1:  /* cs */
 638                     break;
 639                 case 2:
 640                     SS_reg(context) = seg;
 641                     EIP_reg(context) += prefixlen + len + 1;
 642                     return TRUE;
 643                 case 3:
 644                     DS_reg(context) = seg;
 645                     EIP_reg(context) += prefixlen + len + 1;
 646                     return TRUE;
 647                 case 4:
 648                     FS_reg(context) = seg;
 649                     EIP_reg(context) += prefixlen + len + 1;
 650                     return TRUE;
 651                 case 5:
 652                     GS_reg(context) = seg;
 653                     EIP_reg(context) += prefixlen + len + 1;
 654                     return TRUE;
 655                 case 6:  /* unused */
 656                 case 7:  /* unused */
 657                     break;
 658                 }
 659             }
 660             break;  /* Unable to emulate it */
 661
 662         case 0xc4: /* les addr,reg */
 663         case 0xc5: /* lds addr,reg */
 664             if (INSTR_EmulateLDS( context, instr, long_op,
 665                                   long_addr, segprefix, &len ))
 666             {
 667                 EIP_reg(context) += prefixlen + len;
 668                 return TRUE;
 669             }
 670             break;  /* Unable to emulate it */
 671
 672         case 0xcd: /* int <XX> */
 673             if (long_op)
 674             {
 675                 ERR_(int)("int xx from 32-bit code is not supported.\n");
 676                 break;  /* Unable to emulate it */
 677             }
 678             else
 679             {
 680                 FARPROC16 addr = INT_GetPMHandler( instr[1] );
 681                 WORD *stack = (WORD *)STACK_PTR( context );
 682                 /* Push the flags and return address on the stack */
 683                 *(--stack) = LOWORD(EFL_reg(context));
 684                 *(--stack) = CS_reg(context);
 685                 *(--stack) = LOWORD(EIP_reg(context)) + prefixlen + 2;
 686                 ADD_STACK_reg(context, -3 * sizeof(WORD));
 687                 /* Jump to the interrupt handler */
 688                 CS_reg(context)  = HIWORD(addr);
 689                 EIP_reg(context) = LOWORD(addr);
 690             }
 691             return TRUE;
 692
 693         case 0xcf: /* iret */
 694             if (long_op)
 695             {
 696                 DWORD *stack = (DWORD *)STACK_PTR( context );
 697                 EIP_reg(context) = *stack++;
 698                 CS_reg(context)  = *stack++;
 699                 EFL_reg(context) = *stack;
 700                 ADD_STACK_reg(context, 3*sizeof(DWORD));  /* Pop the return address and flags */
 701             }
 702             else
 703             {
 704                 WORD *stack = (WORD *)STACK_PTR( context );
 705                 EIP_reg(context) = *stack++;
 706                 CS_reg(context)  = *stack++;
 707                 SET_LOWORD(EFL_reg(context),*stack);
 708                 ADD_STACK_reg(context, 3*sizeof(WORD));  /* Pop the return address and flags */
 709             }
 710             return TRUE;
 711
 712         case 0xe4: /* inb al,XX */
 713             SET_LOBYTE(EAX_reg(context),INSTR_inport( instr[1], 1, context ));
 714             EIP_reg(context) += prefixlen + 2;
 715             return TRUE;
 716
 717         case 0xe5: /* in (e)ax,XX */
 718             if (long_op)
 719                 EAX_reg(context) = INSTR_inport( instr[1], 4, context );
 720             else
 721                 SET_LOWORD(EAX_reg(context), INSTR_inport( instr[1], 2, context ));
 722             EIP_reg(context) += prefixlen + 2;
 723             return TRUE;
 724
 725         case 0xe6: /* outb XX,al */
 726             INSTR_outport( instr[1], 1, LOBYTE(EAX_reg(context)), context );
 727             EIP_reg(context) += prefixlen + 2;
 728             return TRUE;
 729
 730         case 0xe7: /* out XX,(e)ax */
 731             if (long_op)
 732                 INSTR_outport( instr[1], 4, EAX_reg(context), context );
 733             else
 734                 INSTR_outport( instr[1], 2, LOWORD(EAX_reg(context)), context );
 735             EIP_reg(context) += prefixlen + 2;
 736             return TRUE;
 737
 738         case 0xec: /* inb al,dx */
 739             SET_LOBYTE(EAX_reg(context), INSTR_inport( LOWORD(EDX_reg(context)), 1, context ) );
 740             EIP_reg(context) += prefixlen + 1;
 741             return TRUE;
 742
 743         case 0xed: /* in (e)ax,dx */
 744             if (long_op)
 745                 EAX_reg(context) = INSTR_inport( LOWORD(EDX_reg(context)), 4, context );
 746             else
 747                 SET_LOWORD(EAX_reg(context), INSTR_inport( LOWORD(EDX_reg(context)), 2, context ));
 748             EIP_reg(context) += prefixlen + 1;
 749             return TRUE;
 750
 751         case 0xee: /* outb dx,al */
 752             INSTR_outport( LOWORD(EDX_reg(context)), 1, LOBYTE(EAX_reg(context)), context );
 753             EIP_reg(context) += prefixlen + 1;
 754             return TRUE;
 755
 756         case 0xef: /* out dx,(e)ax */
 757             if (long_op)
 758                 INSTR_outport( LOWORD(EDX_reg(context)), 4, EAX_reg(context), context );
 759             else
 760                 INSTR_outport( LOWORD(EDX_reg(context)), 2, LOWORD(EAX_reg(context)), context );
 761             EIP_reg(context) += prefixlen + 1;
 762             return TRUE;
 763
 764         case 0xfa: /* cli, ignored */
 765             EIP_reg(context) += prefixlen + 1;
 766             return TRUE;
 767
 768         case 0xfb: /* sti, ignored */
 769             EIP_reg(context) += prefixlen + 1;
 770             return TRUE;
 771     }
 772
 773
 774     /* Check for Win16 __GP handler */
 775     gpHandler = HasGPHandler16( PTR_SEG_OFF_TO_SEGPTR( CS_reg(context),
 776                                                        EIP_reg(context) ) );
 777     if (gpHandler)
 778     {
 779         WORD *stack = (WORD *)STACK_PTR( context );
 780         *--stack = CS_reg(context);
 781         *--stack = EIP_reg(context);
 782         ADD_STACK_reg(context, -2*sizeof(WORD));
 783
 784         CS_reg(context) = SELECTOROF( gpHandler );
 785         EIP_reg(context) = OFFSETOF( gpHandler );
 786         return TRUE;
 787     }
 788     return FALSE;  /* Unable to emulate it */
 789 }
 790
 791 #endif  /* __i386__ */