miscemu/instr.c

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