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 "sigcontext.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  * For now, only selector 0x40 is handled here.
  26  */
  27 static WORD INSTR_ReplaceSelector( SIGCONTEXT *context, WORD sel)
  28 {
  29     if (sel == 0x40)
  30     {
  31         extern void SIGNAL_StartBIOSTimer(void);
  32         fprintf( stderr, "Direct access to segment 0x40 (cs:ip=%04x:%04lx).\n",
  33                  CS_sig(context), EIP_sig(context) );
  34         SIGNAL_StartBIOSTimer();
  35         return DOSMEM_BiosSeg;
  36     }
  37     return 0;  /* Can't replace selector */
  38 }
  39
  40
  41 /***********************************************************************
  42  *           INSTR_GetOperandAddr
  43  *
  44  * Return the address of an instruction operand (from the mod/rm byte).
  45  */
  46 static BYTE *INSTR_GetOperandAddr( SIGCONTEXT *context, BYTE *instr,
  47                                    int long_addr, int segprefix, int *len )
  48 {
  49     int mod, rm, base, index = 0, ss = 0, seg = 0, off;
  50
  51 #define GET_VAL(val,type) \
  52     { *val = *(type *)instr; instr += sizeof(type); *len += sizeof(type); }
  53
  54     *len = 0;
  55     GET_VAL( &mod, BYTE );
  56     rm = mod & 7;
  57     mod >>= 6;
  58
  59     if (mod == 3)
  60     {
  61         switch(rm)
  62         {
  63         case 0: return (BYTE *)&EAX_sig(context);
  64         case 1: return (BYTE *)&ECX_sig(context);
  65         case 2: return (BYTE *)&EDX_sig(context);
  66         case 3: return (BYTE *)&EBX_sig(context);
  67         case 4: return (BYTE *)&ESP_sig(context);
  68         case 5: return (BYTE *)&EBP_sig(context);
  69         case 6: return (BYTE *)&ESI_sig(context);
  70         case 7: return (BYTE *)&EDI_sig(context);
  71         }
  72     }
  73
  74     if (long_addr)
  75     {
  76         if (rm == 4)
  77         {
  78             BYTE sib;
  79             GET_VAL( &sib, BYTE );
  80             rm = sib & 7;
  81             ss = sib >> 6;
  82             switch(sib >> 3)
  83             {
  84             case 0: index = EAX_sig(context); break;
  85             case 1: index = ECX_sig(context); break;
  86             case 2: index = EDX_sig(context); break;
  87             case 3: index = EBX_sig(context); break;
  88             case 4: index = 0; break;
  89             case 5: index = EBP_sig(context); break;
  90             case 6: index = ESI_sig(context); break;
  91             case 7: index = EDI_sig(context); break;
  92             }
  93         }
  94
  95         switch(rm)
  96         {
  97         case 0: base = EAX_sig(context); seg = DS_sig(context); break;
  98         case 1: base = ECX_sig(context); seg = DS_sig(context); break;
  99         case 2: base = EDX_sig(context); seg = DS_sig(context); break;
 100         case 3: base = EBX_sig(context); seg = DS_sig(context); break;
 101         case 4: base = ESP_sig(context); seg = SS_sig(context); break;
 102         case 5: base = EBP_sig(context); seg = SS_sig(context); break;
 103         case 6: base = ESI_sig(context); seg = DS_sig(context); break;
 104         case 7: base = EDI_sig(context); seg = DS_sig(context); break;
 105         }
 106         switch (mod)
 107         {
 108         case 0:
 109             if (rm == 5)  /* special case: ds:(disp32) */
 110             {
 111                 GET_VAL( &base, DWORD );
 112                 seg = DS_sig(context);
 113             }
 114             break;
 115
 116         case 1:  /* 8-bit disp */
 117             GET_VAL( &off, BYTE );
 118             base += (signed char)off;
 119             break;
 120
 121         case 2:  /* 32-bit disp */
 122             GET_VAL( &off, DWORD );
 123             base += (signed long)off;
 124             break;
 125         }
 126     }
 127     else  /* short address */
 128     {
 129         switch(rm)
 130         {
 131         case 0:  /* ds:(bx,si) */
 132             base = BX_sig(context) + SI_sig(context);
 133             seg  = DS_sig(context);
 134             break;
 135         case 1:  /* ds:(bx,di) */
 136             base = BX_sig(context) + DI_sig(context);
 137             seg  = DS_sig(context);
 138             break;
 139         case 2:  /* ss:(bp,si) */
 140             base = BP_sig(context) + SI_sig(context);
 141             seg  = SS_sig(context);
 142             break;
 143         case 3:  /* ss:(bp,di) */
 144             base = BP_sig(context) + DI_sig(context);
 145             seg  = SS_sig(context);
 146             break;
 147         case 4:  /* ds:(si) */
 148             base = SI_sig(context);
 149             seg  = DS_sig(context);
 150             break;
 151         case 5:  /* ds:(di) */
 152             base = DI_sig(context);
 153             seg  = DS_sig(context);
 154             break;
 155         case 6:  /* ss:(bp) */
 156             base = BP_sig(context);
 157             seg  = SS_sig(context);
 158             break;
 159         case 7:  /* ds:(bx) */
 160             base = BX_sig(context);
 161             seg  = DS_sig(context);
 162             break;
 163         }
 164
 165         switch(mod)
 166         {
 167         case 0:
 168             if (rm == 6)  /* special case: ds:(disp16) */
 169             {
 170                 GET_VAL( &base, WORD );
 171                 seg  = DS_sig(context);
 172             }
 173             break;
 174
 175         case 1:  /* 8-bit disp */
 176             GET_VAL( &off, BYTE );
 177             base += (signed char)off;
 178             break;
 179
 180         case 2:  /* 16-bit disp */
 181             GET_VAL( &off, WORD );
 182             base += (signed short)off;
 183             break;
 184         }
 185         base &= 0xffff;
 186     }
 187     if (segprefix != -1) seg = segprefix;
 188
 189     /* FIXME: should check limit of the segment here */
 190     return (BYTE *)PTR_SEG_OFF_TO_LIN( seg, (base + (index << ss)) );
 191 #undef GET_VAL
 192 }
 193
 194
 195 /***********************************************************************
 196  *           INSTR_EmulateLDS
 197  *
 198  * Emulate the LDS (and LES,LFS,etc.) instruction.
 199  */
 200 static BOOL32 INSTR_EmulateLDS( SIGCONTEXT *context, BYTE *instr, int long_op,
 201                                 int long_addr, int segprefix, int *len )
 202 {
 203     WORD seg;
 204     BYTE *regmodrm = instr + 1 + (*instr == 0x0f);
 205     BYTE *addr = INSTR_GetOperandAddr( context, regmodrm,
 206                                        long_addr, segprefix, len );
 207     if (!addr)
 208         return FALSE;  /* Unable to emulate it */
 209     seg = *(WORD *)(addr + (long_op ? 4 : 2));
 210
 211     if (!(seg = INSTR_ReplaceSelector( context, seg )))
 212         return FALSE;  /* Unable to emulate it */
 213
 214     /* Now store the offset in the correct register */
 215
 216     switch((*regmodrm >> 3) & 7)
 217     {
 218     case 0:
 219         if (long_op) EAX_sig(context) = *(DWORD *)addr;
 220         else AX_sig(context) = *(WORD *)addr;
 221         break;
 222     case 1:
 223         if (long_op) ECX_sig(context) = *(DWORD *)addr;
 224         else CX_sig(context) = *(WORD *)addr;
 225         break;
 226     case 2:
 227         if (long_op) EDX_sig(context) = *(DWORD *)addr;
 228         else DX_sig(context) = *(WORD *)addr;
 229         break;
 230     case 3:
 231         if (long_op) EBX_sig(context) = *(DWORD *)addr;
 232         else BX_sig(context) = *(WORD *)addr;
 233         break;
 234     case 4:
 235         if (long_op) ESP_sig(context) = *(DWORD *)addr;
 236         else SP_sig(context) = *(WORD *)addr;
 237         break;
 238     case 5:
 239         if (long_op) EBP_sig(context) = *(DWORD *)addr;
 240         else BP_sig(context) = *(WORD *)addr;
 241         break;
 242     case 6:
 243         if (long_op) ESI_sig(context) = *(DWORD *)addr;
 244         else SI_sig(context) = *(WORD *)addr;
 245         break;
 246     case 7:
 247         if (long_op) EDI_sig(context) = *(DWORD *)addr;
 248         else DI_sig(context) = *(WORD *)addr;
 249         break;
 250     }
 251
 252     /* Store the correct segment in the segment register */
 253
 254     switch(*instr)
 255     {
 256     case 0xc4: ES_sig(context) = seg; break;  /* les */
 257     case 0xc5: DS_sig(context) = seg; break;  /* lds */
 258     case 0x0f: switch(instr[1])
 259                {
 260                case 0xb2: SS_sig(context) = seg; break;  /* lss */
 261 #ifdef FS_sig
 262                case 0xb4: FS_sig(context) = seg; break;  /* lfs */
 263 #endif
 264 #ifdef GS_sig
 265                case 0xb5: GS_sig(context) = seg; break;  /* lgs */
 266 #endif
 267                }
 268                break;
 269     }
 270
 271     /* Add the opcode size to the total length */
 272
 273     *len += 1 + (*instr == 0x0f);
 274     return TRUE;
 275 }
 276
 277
 278 /***********************************************************************
 279  *           INSTR_EmulateInstruction
 280  *
 281  * Emulate a priviledged instruction. Returns TRUE if emulation successful.
 282  */
 283 BOOL32 INSTR_EmulateInstruction( SIGCONTEXT *context )
 284 {
 285     int prefix, segprefix, prefixlen, len, repX, long_op, long_addr;
 286     BYTE *instr;
 287
 288     long_op = long_addr = (GET_SEL_FLAGS(CS_sig(context)) & LDT_FLAGS_32BIT) != 0;
 289     instr = (BYTE *) PTR_SEG_OFF_TO_LIN( CS_sig(context), EIP_sig(context) );
 290
 291     /* First handle any possible prefix */
 292
 293     segprefix = -1;  /* no prefix */
 294     prefix = 1;
 295     repX = 0;
 296     prefixlen = 0;
 297     while(prefix)
 298     {
 299         switch(*instr)
 300         {
 301         case 0x2e:
 302             segprefix = CS_sig(context);
 303             break;
 304         case 0x36:
 305             segprefix = SS_sig(context);
 306             break;
 307         case 0x3e:
 308             segprefix = DS_sig(context);
 309             break;
 310         case 0x26:
 311             segprefix = ES_sig(context);
 312             break;
 313 #ifdef FS_sig
 314         case 0x64:
 315             segprefix = FS_sig(context);
 316             break;
 317 #endif
 318 #ifdef GS_sig
 319         case 0x65:
 320             segprefix = GS_sig(context);
 321             break;
 322 #endif
 323         case 0x66:
 324             long_op = !long_op;  /* opcode size prefix */
 325             break;
 326         case 0x67:
 327             long_addr = !long_addr;  /* addr size prefix */
 328             break;
 329         case 0xf0:  /* lock */
 330             break;
 331         case 0xf2:  /* repne */
 332             repX = 1;
 333             break;
 334         case 0xf3:  /* repe */
 335             repX = 2;
 336             break;
 337         default:
 338             prefix = 0;  /* no more prefixes */
 339             break;
 340         }
 341         if (prefix)
 342         {
 343             instr++;
 344             prefixlen++;
 345         }
 346     }
 347
 348     /* Now look at the actual instruction */
 349
 350     switch(*instr)
 351     {
 352         case 0x07: /* pop es */
 353         case 0x17: /* pop ss */
 354         case 0x1f: /* pop ds */
 355             {
 356                 WORD seg = *(WORD *)STACK_PTR( context );
 357                 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 358                 {
 359                     switch(*instr)
 360                     {
 361                     case 0x07: ES_sig(context) = seg; break;
 362                     case 0x17: SS_sig(context) = seg; break;
 363                     case 0x1f: DS_sig(context) = seg; break;
 364                     }
 365                     STACK_sig(context) += long_op ? 4 : 2;
 366                     EIP_sig(context) += prefixlen + 1;
 367                     return TRUE;
 368                 }
 369             }
 370             break;  /* Unable to emulate it */
 371
 372         case 0x0f: /* extended instruction */
 373             switch(instr[1])
 374             {
 375 #ifdef FS_sig
 376             case 0xa1: /* pop fs */
 377                 {
 378                     WORD seg = *(WORD *)STACK_PTR( context );
 379                     if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 380                     {
 381                         FS_sig(context) = seg;
 382                         STACK_sig(context) += long_op ? 4 : 2;
 383                         EIP_sig(context) += prefixlen + 2;
 384                         return TRUE;
 385                     }
 386                 }
 387                 break;
 388 #endif  /* FS_sig */
 389
 390 #ifdef GS_sig
 391             case 0xa9: /* pop gs */
 392                 {
 393                     WORD seg = *(WORD *)STACK_PTR( context );
 394                     if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
 395                     {
 396                         GS_sig(context) = seg;
 397                         STACK_sig(context) += long_op ? 4 : 2;
 398                         EIP_sig(context) += prefixlen + 2;
 399                         return TRUE;
 400                     }
 401                 }
 402                 break;
 403 #endif  /* GS_sig */
 404
 405             case 0xb2: /* lss addr,reg */
 406 #ifdef FS_sig
 407             case 0xb4: /* lfs addr,reg */
 408 #endif
 409 #ifdef GS_sig
 410             case 0xb5: /* lgs addr,reg */
 411 #endif
 412                 if (INSTR_EmulateLDS( context, instr, long_op,
 413                                       long_addr, segprefix, &len ))
 414                 {
 415                     EIP_sig(context) += prefixlen + len;
 416                     return TRUE;
 417                 }
 418                 break;
 419             }
 420             break;  /* Unable to emulate it */
 421
 422         case 0x6c: /* insb     */
 423         case 0x6d: /* insw/d   */
 424         case 0x6e: /* outsb    */
 425         case 0x6f: /* outsw/d  */
 426             {
 427               int typ = *instr;  /* Just in case it's overwritten.  */
 428               int outp = (typ >= 0x6e);
 429               unsigned long count = repX ?
 430                           (long_addr ? ECX_sig(context) : CX_sig(context)) : 1;
 431               int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
 432               int step = (EFL_sig(context) & 0x400) ? -opsize : +opsize;
 433               int seg = outp ? DS_sig(context) : ES_sig(context);  /* FIXME: is this right? */
 434
 435               if (outp)
 436                 /* FIXME: Check segment readable.  */
 437                 (void)0;
 438               else
 439                 /* FIXME: Check segment writeable.  */
 440                 (void)0;
 441
 442               if (repX)
 443                 if (long_addr)
 444                   ECX_sig(context) = 0;
 445                 else
 446                   CX_sig(context) = 0;
 447
 448               while (count-- > 0)
 449                 {
 450                   void *data;
 451                   if (outp)
 452                   {
 453                       data = PTR_SEG_OFF_TO_LIN (seg,
 454                                long_addr ? ESI_sig(context) : SI_sig(context));
 455                       if (long_addr) ESI_sig(context) += step;
 456                       else SI_sig(context) += step;
 457                   }
 458                   else
 459                   {
 460                       data = PTR_SEG_OFF_TO_LIN (seg,
 461                                long_addr ? EDI_sig(context) : DI_sig(context));
 462                       if (long_addr) EDI_sig(context) += step;
 463                       else DI_sig(context) += step;
 464                   }
 465
 466                   switch (typ)
 467                   {
 468                     case 0x6c:
 469                       *((BYTE *)data) = IO_inport( DX_sig(context), 1);
 470                       break;
 471                     case 0x6d:
 472                       if (long_op)
 473                         *((DWORD *)data) = IO_inport( DX_sig(context), 4);
 474                       else
 475                         *((WORD *)data) = IO_inport( DX_sig(context), 2);
 476                       break;
 477                     case 0x6e:
 478                         IO_outport( DX_sig(context), 1, *((BYTE *)data));
 479                         break;
 480                     case 0x6f:
 481                         if (long_op)
 482                             IO_outport( DX_sig(context), 4, *((DWORD *)data));
 483                         else
 484                             IO_outport( DX_sig(context), 2, *((WORD *)data));
 485                         break;
 486                     }
 487                 }
 488               EIP_sig(context) += prefixlen + 1;
 489             }
 490             return TRUE;
 491
 492         case 0x8e: /* mov XX,segment_reg */
 493             {
 494                 WORD seg;
 495                 BYTE *addr = INSTR_GetOperandAddr(context, instr + 1,
 496                                                   long_addr, segprefix, &len );
 497                 if (!addr)
 498                     break;  /* Unable to emulate it */
 499                 seg = *(WORD *)addr;
 500                 if (!(seg = INSTR_ReplaceSelector( context, seg )))
 501                     break;  /* Unable to emulate it */
 502
 503                 switch((instr[1] >> 3) & 7)
 504                 {
 505                 case 0:
 506                     ES_sig(context) = seg;
 507                     EIP_sig(context) += prefixlen + len + 1;
 508                     return TRUE;
 509                 case 1:  /* cs */
 510                     break;
 511                 case 2:
 512                     SS_sig(context) = seg;
 513                     EIP_sig(context) += prefixlen + len + 1;
 514                     return TRUE;
 515                 case 3:
 516                     DS_sig(context) = seg;
 517                     EIP_sig(context) += prefixlen + len + 1;
 518                     return TRUE;
 519                 case 4:
 520 #ifdef FS_sig
 521                     FS_sig(context) = seg;
 522                     EIP_sig(context) += prefixlen + len + 1;
 523                     return TRUE;
 524 #endif
 525                 case 5:
 526 #ifdef GS_sig
 527                     GS_sig(context) = seg;
 528                     EIP_sig(context) += prefixlen + len + 1;
 529                     return TRUE;
 530 #endif
 531                 case 6:  /* unused */
 532                 case 7:  /* unused */
 533                     break;
 534                 }
 535             }
 536             break;  /* Unable to emulate it */
 537
 538         case 0xc4: /* les addr,reg */
 539         case 0xc5: /* lds addr,reg */
 540             if (INSTR_EmulateLDS( context, instr, long_op,
 541                                   long_addr, segprefix, &len ))
 542             {
 543                 EIP_sig(context) += prefixlen + len;
 544                 return TRUE;
 545             }
 546             break;  /* Unable to emulate it */
 547
 548         case 0xcd: /* int <XX> */
 549             if (long_op)
 550             {
 551                 fprintf(stderr, "int xx from 32-bit code is not supported.\n");
 552                 break;  /* Unable to emulate it */
 553             }
 554             else
 555             {
 556                 FARPROC16 addr = INT_GetHandler( instr[1] );
 557                 WORD *stack = (WORD *)STACK_PTR( context );
 558                 /* Push the flags and return address on the stack */
 559                 *(--stack) = FL_sig(context);
 560                 *(--stack) = CS_sig(context);
 561                 *(--stack) = IP_sig(context) + prefixlen + 2;
 562                 STACK_sig(context) -= 3 * sizeof(WORD);
 563                 /* Jump to the interrupt handler */
 564                 CS_sig(context)  = HIWORD(addr);
 565                 EIP_sig(context) = LOWORD(addr);
 566             }
 567             return TRUE;
 568
 569         case 0xcf: /* iret */
 570             if (long_op)
 571             {
 572                 DWORD *stack = (DWORD *)STACK_PTR( context );
 573                 EIP_sig(context) = *stack++;
 574                 CS_sig(context)  = *stack++;
 575                 EFL_sig(context) = *stack;
 576                 STACK_sig(context) += 3*sizeof(DWORD);  /* Pop the return address and flags */
 577             }
 578             else
 579             {
 580                 WORD *stack = (WORD *)STACK_PTR( context );
 581                 EIP_sig(context) = *stack++;
 582                 CS_sig(context)  = *stack++;
 583                 FL_sig(context)  = *stack;
 584                 STACK_sig(context) += 3*sizeof(WORD);  /* Pop the return address and flags */
 585             }
 586             return TRUE;
 587
 588         case 0xe4: /* inb al,XX */
 589             AL_sig(context) = IO_inport( instr[1], 1 );
 590             EIP_sig(context) += prefixlen + 2;
 591             return TRUE;
 592
 593         case 0xe5: /* in (e)ax,XX */
 594             if (long_op) EAX_sig(context) = IO_inport( instr[1], 4 );
 595             else AX_sig(context) = IO_inport( instr[1], 2 );
 596             EIP_sig(context) += prefixlen + 2;
 597             return TRUE;
 598
 599         case 0xe6: /* outb XX,al */
 600             IO_outport( instr[1], 1, AL_sig(context) );
 601             EIP_sig(context) += prefixlen + 2;
 602             return TRUE;
 603
 604         case 0xe7: /* out XX,(e)ax */
 605             if (long_op) IO_outport( instr[1], 4, EAX_sig(context) );
 606             else IO_outport( instr[1], 2, AX_sig(context) );
 607             EIP_sig(context) += prefixlen + 2;
 608             return TRUE;
 609
 610         case 0xec: /* inb al,dx */
 611             AL_sig(context) = IO_inport( DX_sig(context), 1 );
 612             EIP_sig(context) += prefixlen + 1;
 613             return TRUE;
 614
 615         case 0xed: /* in (e)ax,dx */
 616             if (long_op) EAX_sig(context) = IO_inport( DX_sig(context), 4 );
 617             else AX_sig(context) = IO_inport( DX_sig(context), 2 );
 618             EIP_sig(context) += prefixlen + 1;
 619             return TRUE;
 620
 621         case 0xee: /* outb dx,al */
 622             IO_outport( DX_sig(context), 1, AL_sig(context) );
 623             EIP_sig(context) += prefixlen + 1;
 624             return TRUE;
 625
 626         case 0xef: /* out dx,(e)ax */
 627             if (long_op) IO_outport( DX_sig(context), 4, EAX_sig(context) );
 628             else IO_outport( DX_sig(context), 2, AX_sig(context) );
 629             EIP_sig(context) += prefixlen + 1;
 630             return TRUE;
 631
 632         case 0xfa: /* cli, ignored */
 633             EIP_sig(context) += prefixlen + 1;
 634             return TRUE;
 635
 636         case 0xfb: /* sti, ignored */
 637             EIP_sig(context) += prefixlen + 1;
 638             return TRUE;
 639     }
 640     fprintf(stderr, "Unexpected Windows program segfault"
 641                     " - opcode = %x\n", *instr);
 642     return FALSE;  /* Unable to emulate it */
 643 }