miscemu/instr.c

   1 /*
   2  * Emulation of priviledged instructions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  */
   6
   7 #include <stdio.h>
   8 #include "windows.h"
   9 #include "ldt.h"
  10 #include "miscemu.h"
  11 #include "sig_context.h"
  12
  13
  14 #define STACK_sig(context) \
  15    ((GET_SEL_FLAGS(SS_sig(context)) & LDT_FLAGS_32BIT) ? \
  16                    ESP_sig(context) : SP_sig(context))
  17
  18 #define STACK_PTR(context) \
  19     (PTR_SEG_OFF_TO_LIN(SS_sig(context),STACK_sig(context)))
  20
  21 /***********************************************************************
  22  *           INSTR_ReplaceSelector
  23  *
  24  * Try to replace an invalid selector by a valid one.
  25  * The only selector where it is allowed to do "mov ax,40;mov es,ax"
  26  * is the so called 'bimodal' selector 0x40, which points to the BIOS
  27  * data segment. Used by (at least) Borland products (and programs compiled
  28  * using Borland products).
  29  *
  30  * See Undocumented Windows, Chapter 5, __0040.
  31  */
  32 static WORD INSTR_ReplaceSelector( SIGCONTEXT *context, WORD sel)
  33 {
  34     if (sel == 0x40)
  35     {
  36         static WORD sys_timer = 0;
  37         if (!sys_timer)
  38             sys_timer = CreateSystemTimer( 55, (FARPROC16)DOSMEM_Tick );
  39         return DOSMEM_BiosSeg;
  40     }
  41     return 0;  /* Can't replace selector, crashdump */
  42 }
  43
  44
  45 /***********************************************************************
  46  *           INSTR_GetOperandAddr
  47  *
  48  * Return the address of an instruction operand (from the mod/rm byte).
  49  */
  50 static BYTE *INSTR_GetOperandAddr( SIGCONTEXT *context, BYTE *instr,
  51                                    int long_addr, int segprefix, int *len )
  52 {
  53     int mod, rm, base, index = 0, ss = 0, seg = 0, off;
  54
  55 #define GET_VAL(val,type) \
  56     { *val = *(type *)instr; instr += sizeof(type); *len += sizeof(type); }
  57
  58     *len = 0;
  59     GET_VAL( &mod, BYTE );
  60     rm = mod & 7;
  61     mod >>= 6;
  62
  63     if (mod == 3)
  64     {
  65         switch(rm)
  66         {
  67         case 0: return (BYTE *)&EAX_sig(context);
  68         case 1: return (BYTE *)&ECX_sig(context);
  69         case 2: return (BYTE *)&EDX_sig(context);
  70         case 3: return (BYTE *)&EBX_sig(context);
  71         case 4: return (BYTE *)&ESP_sig(context);
  72         case 5: return (BYTE *)&EBP_sig(context);
  73         case 6: return (BYTE *)&ESI_sig(context);
  74         case 7: return (BYTE *)&EDI_sig(context);
  75         }
  76     }
  77
  78     if (long_addr)
  79     {
  80         if (rm == 4)
  81         {
  82             BYTE sib;
  83             GET_VAL( &sib, BYTE );
  84             rm = sib & 7;
  85             ss = sib >> 6;
  86             switch(sib >> 3)
  87             {
  88             case 0: index = EAX_sig(context); break;
  89             case 1: index = ECX_sig(context); break;
  90             case 2: index = EDX_sig(context); break;
  91             case 3: index = EBX_sig(context); break;
  92             case 4: index = 0; break;
  93             case 5: index = EBP_sig(context); break;
  94             case 6: index = ESI_sig(context); break;
  95             case 7: index = EDI_sig(context); break;
  96             }
  97         }
  98
  99         switch(rm)
 100         {
 101         case 0: base = EAX_sig(context); seg = DS_sig(context); break;
 102         case 1: base = ECX_sig(context); seg = DS_sig(context); break;
 103         case 2: base = EDX_sig(context); seg = DS_sig(context); break;
 104         case 3: base = EBX_sig(context); seg = DS_sig(context); break;
 105         case 4: base = ESP_sig(context); seg = SS_sig(context); break;
 106         case 5: base = EBP_sig(context); seg = SS_sig(context); break;
 107         case 6: base = ESI_sig(context); seg = DS_sig(context); break;
 108         case 7: base = EDI_sig(context); seg = DS_sig(context); break;
 109         }
 110         switch (mod)
 111         {
 112         case 0:
 113             if (rm == 5)  /* special case: ds:(disp32) */
 114             {
 115                 GET_VAL( &base, DWORD );
 116                 seg = DS_sig(context);
 117             }
 118             break;
 119
 120         case 1:  /* 8-bit disp */
 121             GET_VAL( &off, BYTE );
 122             base += (signed char)off;
 123             break;
 124
 125         case 2:  /* 32-bit disp */
 126             GET_VAL( &off, DWORD );
 127             base += (signed long)off;
 128             break;
 129         }
 130     }
 131     else  /* short address */
 132     {
 133         switch(rm)
 134         {
 135         case 0:  /* ds:(bx,si) */
 136             base = BX_sig(context) + SI_sig(context);
 137             seg  = DS_sig(context);
 138             break;
 139         case 1:  /* ds:(bx,di) */
 140             base = BX_sig(context) + DI_sig(context);
 141             seg  = DS_sig(context);
 142             break;
 143         case 2:  /* ss:(bp,si) */
 144             base = BP_sig(context) + SI_sig(context);
 145             seg  = SS_sig(context);
 146             break;
 147         case 3:  /* ss:(bp,di) */
 148             base = BP_sig(context) + DI_sig(context);
 149             seg  = SS_sig(context);
 150             break;
 151         case 4:  /* ds:(si) */
 152             base = SI_sig(context);
 153             seg  = DS_sig(context);
 154             break;
 155         case 5:  /* ds:(di) */
 156             base = DI_sig(context);
 157             seg  = DS_sig(context);
 158             break;
 159         case 6:  /* ss:(bp) */
 160             base = BP_sig(context);
 161             seg  = SS_sig(context);
 162             break;
 163         case 7:  /* ds:(bx) */
 164             base = BX_sig(context);
 165             seg  = DS_sig(context);
 166             break;
 167         }
 168
 169         switch(mod)
 170         {
 171         case 0:
 172             if (rm == 6)  /* special case: ds:(disp16) */
 173             {
 174                 GET_VAL( &base, WORD );
 175                 seg  = DS_sig(context);
 176             }
 177             break;
 178
 179         case 1:  /* 8-bit disp */
 180             GET_VAL( &off, BYTE );
 181             base += (signed char)off;
 182             break;
 183
 184         case 2:  /* 16-bit disp */
 185             GET_VAL( &off, WORD );
 186             base += (signed short)off;
 187             break;
 188         }
 189         base &= 0xffff;
 190     }
 191     if (segprefix != -1) seg = segprefix;
 192
 193     /* Make sure the segment and offset are valid */
 194     if (((seg & 7) != 7) || IS_SELECTOR_FREE(seg)) return NULL;
 195     if (GET_SEL_LIMIT(seg) < (base + (index << ss))) return NULL;
 196     return (BYTE *)PTR_SEG_OFF_TO_LIN( seg, (base + (index << ss)) );
 197 #undef GET_VAL
 198 }
 199
 200
 201 /***********************************************************************
 202  *           INSTR_EmulateLDS
 203  *
 204  * Emulate the LDS (and LES,LFS,etc.) instruction.
 205  */
 206 static BOOL32 INSTR_EmulateLDS( SIGCONTEXT *context, BYTE *instr, int long_op,
 207                                 int long_addr, int segprefix, int *len )
 208 {
 209     WORD seg;
 210     BYTE *regmodrm = instr + 1 + (*instr == 0x0f);
 211     BYTE *addr = INSTR_GetOperandAddr( context, regmodrm,
 212                                        long_addr, segprefix, len );
 213     if (!addr)
 214         return FALSE;  /* Unable to emulate it */
 215     seg = *(WORD *)(addr + (long_op ? 4 : 2));
 216
 217     if (!(seg = INSTR_ReplaceSelector( context, seg )))
 218         return FALSE;  /* Unable to emulate it */
 219
 220     /* Now store the offset in the correct register */
 221
 222     switch((*regmodrm >> 3) & 7)
 223     {
 224     case 0:
 225         if (long_op) EAX_sig(context) = *(DWORD *)addr;
 226         else AX_sig(context) = *(WORD *)addr;
 227         break;
 228     case 1:
 229         if (long_op) ECX_sig(context) = *(DWORD *)addr;
 230         else CX_sig(context) = *(WORD *)addr;
 231         break;
 232     case 2:
 233         if (long_op) EDX_sig(context) = *(DWORD *)addr;
 234         else DX_sig(context) = *(WORD *)addr;
 235         break;
 236     case 3:
 237         if (long_op) EBX_sig(context) = *(DWORD *)addr;
 238         else BX_sig(context) = *(WORD *)addr;
 239         break;
 240     case 4:
 241         if (long_op) ESP_sig(context) = *(DWORD *)addr;
 242         else SP_sig(context) = *(WORD *)addr;
 243         break;
 244     case 5:
 245         if (long_op) EBP_sig(context) = *(DWORD *)addr;
 246         else BP_sig(context) = *(WORD *)addr;
 247         break;
 248     case 6:
 249         if (long_op) ESI_sig(context) = *(DWORD *)addr;
 250         else SI_sig(context) = *(WORD *)addr;
 251         break;
 252     case 7:
 253         if (long_op) EDI_sig(context) = *(DWORD *)addr;
 254         else DI_sig(context) = *(WORD *)addr;
 255         break;
 256     }
 257
 258     /* Store the correct segment in the segment register */
 259
 260     switch(*instr)
 261     {
 262     case 0xc4: ES_sig(context) = seg; break;  /* les */
 263     case 0xc5: DS_sig(context) = seg; break;  /* lds */
 264     case 0x0f: switch(instr[1])
 265                {
 266                case 0xb2: SS_sig(context) = seg; break;  /* lss */
 267 #ifdef FS_sig
 268                case 0xb4: FS_sig(context) = seg; break;  /* lfs */
 269 #endif
 270 #ifdef GS_sig
 271                case 0xb5: GS_sig(context) = seg; break;  /* lgs */
 272 #endif
 273                }
 274                break;
 275     }
 276
 277     /* Add the opcode size to the total length */
 278
 279     *len += 1 + (*instr == 0x0f);
 280     return TRUE;
 281 }
 282
 283
 284 /***********************************************************************
 285  *           INSTR_EmulateInstruction
 286  *
 287  * Emulate a priviledged instruction. Returns TRUE if emulation successful.
 288  */
 289 BOOL32 INSTR_EmulateInstruction( SIGCONTEXT *context )
 290 {
 291     int prefix, segprefix, prefixlen, len, repX, long_op, long_addr;
 292     BYTE *instr;
 293
 294     long_op = long_addr = (GET_SEL_FLAGS(CS_sig(context)) & LDT_FLAGS_32BIT) != 0;
 295     instr = (BYTE *) PTR_SEG_OFF_TO_LIN( CS_sig(context), EIP_sig(context) );
 296
 297     /* First handle any possible prefix */
 298
 299     segprefix = -1;  /* no prefix */
 300     prefix = 1;
 301     repX = 0;
 302     prefixlen = 0;
 303     while(prefix)
 304     {
 305         switch(*instr)
 306         {
 307         case 0x2e:
 308             segprefix = CS_sig(context);
 309             break;
 310         case 0x36:
 311             segprefix = SS_sig(context);
 312             break;
 313         case 0x3e:
 314             segprefix = DS_sig(context);
 315             break;
 316         case 0x26:
 317             segprefix = ES_sig(context);
 318             break;
 319 #ifdef FS_sig
 320         case 0x64:
 321             segprefix = FS_sig(context);
 322             break;
 323 #endif
 324 #ifdef GS_sig
 325         case 0x65:
 326             segprefix = GS_sig(context);
 327             break;
 328 #endif
 329         case 0x66:
 330             long_op = !long_op;  /* opcode size prefix */
 331             break;
 332         case 0x67:
 333             long_addr = !long_addr;  /* addr size prefix */
 334             break;
 335         case 0xf0:  /* lock */
 336             break;
 337         case 0xf2:  /* repne */
 338             repX = 1;
 339             break;
 340         case 0xf3:  /* repe */
 341             repX = 2;
 342             break;
 343         default:
 344             prefix = 0;  /* no more prefixes */
 345             break;
 346         }
 347         if (prefix)
 348         {
 349             instr++;
 350             prefixlen++;
 351         }
 352     }
 353
 354     /* Now look at the actual instruction */
 355
 356     switch(*instr)
 357     {
 358         case 0x07: /* pop es */
 359         case 0x17: /* pop ss */
 360         case 0x1f: /* pop ds */
 361             {
 362                 WORD seg = *(WORD *)STACK_PTR( context );
 363                 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 364                 {
 365                     switch(*instr)
 366                     {
 367                     case 0x07: ES_sig(context) = seg; break;
 368                     case 0x17: SS_sig(context) = seg; break;
 369                     case 0x1f: DS_sig(context) = seg; break;
 370                     }
 371                     STACK_sig(context) += long_op ? 4 : 2;
 372                     EIP_sig(context) += prefixlen + 1;
 373                     return TRUE;
 374                 }
 375             }
 376             break;  /* Unable to emulate it */
 377
 378         case 0x0f: /* extended instruction */
 379             switch(instr[1])
 380             {
 381 #ifdef FS_sig
 382             case 0xa1: /* pop fs */
 383                 {
 384                     WORD seg = *(WORD *)STACK_PTR( context );
 385                     if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 386                     {
 387                         FS_sig(context) = seg;
 388                         STACK_sig(context) += long_op ? 4 : 2;
 389                         EIP_sig(context) += prefixlen + 2;
 390                         return TRUE;
 391                     }
 392                 }
 393                 break;
 394 #endif  /* FS_sig */
 395
 396 #ifdef GS_sig
 397             case 0xa9: /* pop gs */
 398                 {
 399                     WORD seg = *(WORD *)STACK_PTR( context );
 400                     if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 401                     {
 402                         GS_sig(context) = seg;
 403                         STACK_sig(context) += long_op ? 4 : 2;
 404                         EIP_sig(context) += prefixlen + 2;
 405                         return TRUE;
 406                     }
 407                 }
 408                 break;
 409 #endif  /* GS_sig */
 410
 411             case 0xb2: /* lss addr,reg */
 412 #ifdef FS_sig
 413             case 0xb4: /* lfs addr,reg */
 414 #endif
 415 #ifdef GS_sig
 416             case 0xb5: /* lgs addr,reg */
 417 #endif
 418                 if (INSTR_EmulateLDS( context, instr, long_op,
 419                                       long_addr, segprefix, &len ))
 420                 {
 421                     EIP_sig(context) += prefixlen + len;
 422                     return TRUE;
 423                 }
 424                 break;
 425             }
 426             break;  /* Unable to emulate it */
 427
 428         case 0x6c: /* insb     */
 429         case 0x6d: /* insw/d   */
 430         case 0x6e: /* outsb    */
 431         case 0x6f: /* outsw/d  */
 432             {
 433               int typ = *instr;  /* Just in case it's overwritten.  */
 434               int outp = (typ >= 0x6e);
 435               unsigned long count = repX ?
 436                           (long_addr ? ECX_sig(context) : CX_sig(context)) : 1;
 437               int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
 438               int step = (EFL_sig(context) & 0x400) ? -opsize : +opsize;
 439               int seg = outp ? DS_sig(context) : ES_sig(context);  /* FIXME: is this right? */
 440
 441               if (outp)
 442                 /* FIXME: Check segment readable.  */
 443                 (void)0;
 444               else
 445                 /* FIXME: Check segment writeable.  */
 446                 (void)0;
 447
 448               if (repX)
 449                 if (long_addr)
 450                   ECX_sig(context) = 0;
 451                 else
 452                   CX_sig(context) = 0;
 453
 454               while (count-- > 0)
 455                 {
 456                   void *data;
 457                   if (outp)
 458                   {
 459                       data = PTR_SEG_OFF_TO_LIN (seg,
 460                                long_addr ? ESI_sig(context) : SI_sig(context));
 461                       if (long_addr) ESI_sig(context) += step;
 462                       else SI_sig(context) += step;
 463                   }
 464                   else
 465                   {
 466                       data = PTR_SEG_OFF_TO_LIN (seg,
 467                                long_addr ? EDI_sig(context) : DI_sig(context));
 468                       if (long_addr) EDI_sig(context) += step;
 469                       else DI_sig(context) += step;
 470                   }
 471
 472                   switch (typ)
 473                   {
 474                     case 0x6c:
 475                       *((BYTE *)data) = IO_inport( DX_sig(context), 1);
 476                       break;
 477                     case 0x6d:
 478                       if (long_op)
 479                         *((DWORD *)data) = IO_inport( DX_sig(context), 4);
 480                       else
 481                         *((WORD *)data) = IO_inport( DX_sig(context), 2);
 482                       break;
 483                     case 0x6e:
 484                         IO_outport( DX_sig(context), 1, *((BYTE *)data));
 485                         break;
 486                     case 0x6f:
 487                         if (long_op)
 488                             IO_outport( DX_sig(context), 4, *((DWORD *)data));
 489                         else
 490                             IO_outport( DX_sig(context), 2, *((WORD *)data));
 491                         break;
 492                     }
 493                 }
 494               EIP_sig(context) += prefixlen + 1;
 495             }
 496             return TRUE;
 497
 498         case 0x8e: /* mov XX,segment_reg */
 499             {
 500                 WORD seg;
 501                 BYTE *addr = INSTR_GetOperandAddr(context, instr + 1,
 502                                                   long_addr, segprefix, &len );
 503                 if (!addr)
 504                     break;  /* Unable to emulate it */
 505                 seg = *(WORD *)addr;
 506                 if (!(seg = INSTR_ReplaceSelector( context, seg )))
 507                     break;  /* Unable to emulate it */
 508
 509                 switch((instr[1] >> 3) & 7)
 510                 {
 511                 case 0:
 512                     ES_sig(context) = seg;
 513                     EIP_sig(context) += prefixlen + len + 1;
 514                     return TRUE;
 515                 case 1:  /* cs */
 516                     break;
 517                 case 2:
 518                     SS_sig(context) = seg;
 519                     EIP_sig(context) += prefixlen + len + 1;
 520                     return TRUE;
 521                 case 3:
 522                     DS_sig(context) = seg;
 523                     EIP_sig(context) += prefixlen + len + 1;
 524                     return TRUE;
 525                 case 4:
 526 #ifdef FS_sig
 527                     FS_sig(context) = seg;
 528                     EIP_sig(context) += prefixlen + len + 1;
 529                     return TRUE;
 530 #endif
 531                 case 5:
 532 #ifdef GS_sig
 533                     GS_sig(context) = seg;
 534                     EIP_sig(context) += prefixlen + len + 1;
 535                     return TRUE;
 536 #endif
 537                 case 6:  /* unused */
 538                 case 7:  /* unused */
 539                     break;
 540                 }
 541             }
 542             break;  /* Unable to emulate it */
 543
 544         case 0xc4: /* les addr,reg */
 545         case 0xc5: /* lds addr,reg */
 546             if (INSTR_EmulateLDS( context, instr, long_op,
 547                                   long_addr, segprefix, &len ))
 548             {
 549                 EIP_sig(context) += prefixlen + len;
 550                 return TRUE;
 551             }
 552             break;  /* Unable to emulate it */
 553
 554         case 0xcd: /* int <XX> */
 555             if (long_op)
 556             {
 557                 fprintf(stderr, "int xx from 32-bit code is not supported.\n");
 558                 break;  /* Unable to emulate it */
 559             }
 560             else
 561             {
 562                 FARPROC16 addr = INT_GetHandler( instr[1] );
 563                 WORD *stack = (WORD *)STACK_PTR( context );
 564                 /* Push the flags and return address on the stack */
 565                 *(--stack) = FL_sig(context);
 566                 *(--stack) = CS_sig(context);
 567                 *(--stack) = IP_sig(context) + prefixlen + 2;
 568                 STACK_sig(context) -= 3 * sizeof(WORD);
 569                 /* Jump to the interrupt handler */
 570                 CS_sig(context)  = HIWORD(addr);
 571                 EIP_sig(context) = LOWORD(addr);
 572             }
 573             return TRUE;
 574
 575         case 0xcf: /* iret */
 576             if (long_op)
 577             {
 578                 DWORD *stack = (DWORD *)STACK_PTR( context );
 579                 EIP_sig(context) = *stack++;
 580                 CS_sig(context)  = *stack++;
 581                 EFL_sig(context) = *stack;
 582                 STACK_sig(context) += 3*sizeof(DWORD);  /* Pop the return address and flags */
 583             }
 584             else
 585             {
 586                 WORD *stack = (WORD *)STACK_PTR( context );
 587                 EIP_sig(context) = *stack++;
 588                 CS_sig(context)  = *stack++;
 589                 FL_sig(context)  = *stack;
 590                 STACK_sig(context) += 3*sizeof(WORD);  /* Pop the return address and flags */
 591             }
 592             return TRUE;
 593
 594         case 0xe4: /* inb al,XX */
 595             AL_sig(context) = IO_inport( instr[1], 1 );
 596             EIP_sig(context) += prefixlen + 2;
 597             return TRUE;
 598
 599         case 0xe5: /* in (e)ax,XX */
 600             if (long_op) EAX_sig(context) = IO_inport( instr[1], 4 );
 601             else AX_sig(context) = IO_inport( instr[1], 2 );
 602             EIP_sig(context) += prefixlen + 2;
 603             return TRUE;
 604
 605         case 0xe6: /* outb XX,al */
 606             IO_outport( instr[1], 1, AL_sig(context) );
 607             EIP_sig(context) += prefixlen + 2;
 608             return TRUE;
 609
 610         case 0xe7: /* out XX,(e)ax */
 611             if (long_op) IO_outport( instr[1], 4, EAX_sig(context) );
 612             else IO_outport( instr[1], 2, AX_sig(context) );
 613             EIP_sig(context) += prefixlen + 2;
 614             return TRUE;
 615
 616         case 0xec: /* inb al,dx */
 617             AL_sig(context) = IO_inport( DX_sig(context), 1 );
 618             EIP_sig(context) += prefixlen + 1;
 619             return TRUE;
 620
 621         case 0xed: /* in (e)ax,dx */
 622             if (long_op) EAX_sig(context) = IO_inport( DX_sig(context), 4 );
 623             else AX_sig(context) = IO_inport( DX_sig(context), 2 );
 624             EIP_sig(context) += prefixlen + 1;
 625             return TRUE;
 626
 627         case 0xee: /* outb dx,al */
 628             IO_outport( DX_sig(context), 1, AL_sig(context) );
 629             EIP_sig(context) += prefixlen + 1;
 630             return TRUE;
 631
 632         case 0xef: /* out dx,(e)ax */
 633             if (long_op) IO_outport( DX_sig(context), 4, EAX_sig(context) );
 634             else IO_outport( DX_sig(context), 2, AX_sig(context) );
 635             EIP_sig(context) += prefixlen + 1;
 636             return TRUE;
 637
 638         case 0xfa: /* cli, ignored */
 639             EIP_sig(context) += prefixlen + 1;
 640             return TRUE;
 641
 642         case 0xfb: /* sti, ignored */
 643             EIP_sig(context) += prefixlen + 1;
 644             return TRUE;
 645     }
 646     fprintf(stderr, "Unexpected Windows program segfault"
 647                     " - opcode = %x\n", *instr);
 648     return FALSE;  /* Unable to emulate it */
 649 }