memory/instr.c

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