2 * Emulation of priviledged instructions
4 * Copyright 1995 Alexandre Julliard
11 #include "registers.h"
14 #define STACK_reg(context) \
15 ((GET_SEL_FLAGS(SS_reg(context)) & LDT_FLAGS_32BIT) ? \
16 ESP_reg(context) : SP_reg(context))
18 #define STACK_PTR(context) \
19 (PTR_SEG_OFF_TO_LIN(SS_reg(context),STACK_reg(context)))
21 /***********************************************************************
22 * INSTR_ReplaceSelector
24 * Try to replace an invalid selector by a valid one.
25 * For now, only selector 0x40 is handled here.
27 static WORD INSTR_ReplaceSelector( struct sigcontext_struct *context, WORD sel)
31 fprintf( stderr, "Direct access to segment 0x40 (cs:ip=%04x:%04lx).\n",
32 CS_reg(context), EIP_reg(context) );
33 DOSMEM_Alarm(); /* Increment BIOS clock */
34 return DOSMEM_BiosSeg;
36 return 0; /* Can't replace selector */
40 /***********************************************************************
41 * INSTR_GetOperandAddr
43 * Return the address of an instruction operand (from the mod/rm byte).
45 static BYTE *INSTR_GetOperandAddr( struct sigcontext_struct *context,
46 BYTE *instr, int long_addr,
47 int segprefix, int *len )
49 int mod, rm, base, index = 0, ss = 0, seg = 0, off;
51 #define GET_VAL(val,type) \
52 { *val = *(type *)instr; instr += sizeof(type); *len += sizeof(type); }
55 GET_VAL( &mod, BYTE );
63 case 0: return (BYTE *)&EAX_reg(context);
64 case 1: return (BYTE *)&ECX_reg(context);
65 case 2: return (BYTE *)&EDX_reg(context);
66 case 3: return (BYTE *)&EBX_reg(context);
67 case 4: return (BYTE *)&ESP_reg(context);
68 case 5: return (BYTE *)&EBP_reg(context);
69 case 6: return (BYTE *)&ESI_reg(context);
70 case 7: return (BYTE *)&EDI_reg(context);
79 GET_VAL( &sib, BYTE );
84 case 0: index = EAX_reg(context); break;
85 case 1: index = ECX_reg(context); break;
86 case 2: index = EDX_reg(context); break;
87 case 3: index = EBX_reg(context); break;
88 case 4: index = 0; break;
89 case 5: index = EBP_reg(context); break;
90 case 6: index = ESI_reg(context); break;
91 case 7: index = EDI_reg(context); break;
97 case 0: base = EAX_reg(context); seg = DS_reg(context); break;
98 case 1: base = ECX_reg(context); seg = DS_reg(context); break;
99 case 2: base = EDX_reg(context); seg = DS_reg(context); break;
100 case 3: base = EBX_reg(context); seg = DS_reg(context); break;
101 case 4: base = ESP_reg(context); seg = SS_reg(context); break;
102 case 5: base = EBP_reg(context); seg = SS_reg(context); break;
103 case 6: base = ESI_reg(context); seg = DS_reg(context); break;
104 case 7: base = EDI_reg(context); seg = DS_reg(context); break;
109 if (rm == 5) /* special case: ds:(disp32) */
111 GET_VAL( &base, DWORD );
112 seg = DS_reg(context);
116 case 1: /* 8-bit disp */
117 GET_VAL( &off, BYTE );
118 base += (signed char)off;
121 case 2: /* 32-bit disp */
122 GET_VAL( &off, DWORD );
123 base += (signed long)off;
127 else /* short address */
131 case 0: /* ds:(bx,si) */
132 base = BX_reg(context) + SI_reg(context);
133 seg = DS_reg(context);
135 case 1: /* ds:(bx,di) */
136 base = BX_reg(context) + DI_reg(context);
137 seg = DS_reg(context);
139 case 2: /* ss:(bp,si) */
140 base = BP_reg(context) + SI_reg(context);
141 seg = SS_reg(context);
143 case 3: /* ss:(bp,di) */
144 base = BP_reg(context) + DI_reg(context);
145 seg = SS_reg(context);
147 case 4: /* ds:(si) */
148 base = SI_reg(context);
149 seg = DS_reg(context);
151 case 5: /* ds:(di) */
152 base = DI_reg(context);
153 seg = DS_reg(context);
155 case 6: /* ss:(bp) */
156 base = BP_reg(context);
157 seg = SS_reg(context);
159 case 7: /* ds:(bx) */
160 base = BX_reg(context);
161 seg = DS_reg(context);
168 if (rm == 6) /* special case: ds:(disp16) */
170 GET_VAL( &base, WORD );
171 seg = DS_reg(context);
175 case 1: /* 8-bit disp */
176 GET_VAL( &off, BYTE );
177 base += (signed char)off;
180 case 2: /* 16-bit disp */
181 GET_VAL( &off, WORD );
182 base += (signed short)off;
187 if (segprefix != -1) seg = segprefix;
189 /* FIXME: should check limit of the segment here */
190 return (BYTE *)PTR_SEG_OFF_TO_LIN( seg, (base + (index << ss)) );
194 /***********************************************************************
197 * Emulate the LDS (and LES,LFS,etc.) instruction.
199 static BOOL INSTR_EmulateLDS( struct sigcontext_struct *context,
200 BYTE *instr, int long_op, int long_addr,
201 int segprefix, int *len )
203 BYTE *regmodrm = instr + 1 + (*instr == 0x0f);
204 BYTE *addr = INSTR_GetOperandAddr( context, regmodrm,
205 long_addr, segprefix, len );
206 WORD seg = *(WORD *)(addr + (long_op ? 4 : 2));
208 if (!(seg = INSTR_ReplaceSelector( context, seg )))
209 return FALSE; /* Unable to emulate it */
211 /* Now store the offset in the correct register */
213 switch((*regmodrm >> 3) & 7)
216 if (long_op) EAX_reg(context) = *(DWORD *)addr;
217 else AX_reg(context) = *(WORD *)addr;
220 if (long_op) ECX_reg(context) = *(DWORD *)addr;
221 else CX_reg(context) = *(WORD *)addr;
224 if (long_op) EDX_reg(context) = *(DWORD *)addr;
225 else DX_reg(context) = *(WORD *)addr;
228 if (long_op) EBX_reg(context) = *(DWORD *)addr;
229 else BX_reg(context) = *(WORD *)addr;
232 if (long_op) ESP_reg(context) = *(DWORD *)addr;
233 else SP_reg(context) = *(WORD *)addr;
236 if (long_op) EBP_reg(context) = *(DWORD *)addr;
237 else BP_reg(context) = *(WORD *)addr;
240 if (long_op) ESI_reg(context) = *(DWORD *)addr;
241 else SI_reg(context) = *(WORD *)addr;
244 if (long_op) EDI_reg(context) = *(DWORD *)addr;
245 else DI_reg(context) = *(WORD *)addr;
249 /* Store the correct segment in the segment register */
253 case 0xc4: ES_reg(context) = seg; break; /* les */
254 case 0xc5: DS_reg(context) = seg; break; /* lds */
255 case 0x0f: switch(instr[1])
257 case 0xb2: SS_reg(context) = seg; break; /* lss */
259 case 0xb4: FS_reg(context) = seg; break; /* lfs */
262 case 0xb5: GS_reg(context) = seg; break; /* lgs */
268 /* Add the opcode size to the total length */
270 *len += 1 + (*instr == 0x0f);
275 /***********************************************************************
276 * INSTR_EmulateInstruction
278 * Emulate a priviledged instruction. Returns TRUE if emulation successful.
280 BOOL INSTR_EmulateInstruction( struct sigcontext_struct *context )
282 int prefix, segprefix, prefixlen, len, repX, long_op, long_addr;
285 long_op = long_addr = (GET_SEL_FLAGS(CS_reg(context)) & LDT_FLAGS_32BIT) != 0;
286 instr = (BYTE *) PTR_SEG_OFF_TO_LIN( CS_reg(context), EIP_reg(context) );
288 /* First handle any possible prefix */
290 segprefix = -1; /* no prefix */
299 segprefix = CS_reg(context);
302 segprefix = SS_reg(context);
305 segprefix = DS_reg(context);
308 segprefix = ES_reg(context);
312 segprefix = FS_reg(context);
317 segprefix = GS_reg(context);
321 long_op = !long_op; /* opcode size prefix */
324 long_addr = !long_addr; /* addr size prefix */
326 case 0xf0: /* lock */
328 case 0xf2: /* repne */
331 case 0xf3: /* repe */
335 prefix = 0; /* no more prefixes */
345 /* Now look at the actual instruction */
349 case 0x07: /* pop es */
350 case 0x17: /* pop ss */
351 case 0x1f: /* pop ds */
353 WORD seg = *(WORD *)STACK_PTR( context );
354 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
358 case 0x07: ES_reg(context) = seg; break;
359 case 0x17: SS_reg(context) = seg; break;
360 case 0x1f: DS_reg(context) = seg; break;
362 STACK_reg(context) += long_op ? 4 : 2;
363 EIP_reg(context) += prefixlen + 1;
367 break; /* Unable to emulate it */
369 case 0x0f: /* extended instruction */
373 case 0xa1: /* pop fs */
375 WORD seg = *(WORD *)STACK_PTR( context );
376 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
378 FS_reg(context) = seg;
379 STACK_reg(context) += long_op ? 4 : 2;
380 EIP_reg(context) += prefixlen + 2;
388 case 0xa9: /* pop gs */
390 WORD seg = *(WORD *)STACK_PTR( context );
391 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
393 GS_reg(context) = seg;
394 STACK_reg(context) += long_op ? 4 : 2;
395 EIP_reg(context) += prefixlen + 2;
402 case 0xb2: /* lss addr,reg */
404 case 0xb4: /* lfs addr,reg */
407 case 0xb5: /* lgs addr,reg */
409 if (INSTR_EmulateLDS( context, instr, long_op,
410 long_addr, segprefix, &len ))
412 EIP_reg(context) += prefixlen + len;
417 break; /* Unable to emulate it */
419 case 0x6c: /* insb */
420 case 0x6d: /* insw/d */
421 case 0x6e: /* outsb */
422 case 0x6f: /* outsw/d */
424 int typ = *instr; /* Just in case it's overwritten. */
425 int outp = (typ >= 0x6e);
426 unsigned long count = repX ?
427 (long_addr ? ECX_reg(context) : CX_reg(context)) : 1;
428 int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
429 int step = (EFL_reg(context) & 0x400) ? -opsize : +opsize;
430 int seg = outp ? DS_reg(context) : ES_reg(context); /* FIXME: is this right? */
433 /* FIXME: Check segment readable. */
436 /* FIXME: Check segment writeable. */
441 ECX_reg(context) = 0;
450 data = PTR_SEG_OFF_TO_LIN (seg,
451 long_addr ? ESI_reg(context) : SI_reg(context));
452 if (long_addr) ESI_reg(context) += step;
453 else SI_reg(context) += step;
457 data = PTR_SEG_OFF_TO_LIN (seg,
458 long_addr ? EDI_reg(context) : DI_reg(context));
459 if (long_addr) EDI_reg(context) += step;
460 else DI_reg(context) += step;
466 *((BYTE *)data) = inport( DX_reg(context), 1);
470 *((DWORD *)data) = inport( DX_reg(context), 4);
472 *((WORD *)data) = inport( DX_reg(context), 2);
475 outport( DX_reg(context), 1, *((BYTE *)data));
479 outport( DX_reg(context), 4, *((DWORD *)data));
481 outport( DX_reg(context), 2, *((WORD *)data));
485 EIP_reg(context) += prefixlen + 1;
489 case 0x8e: /* mov XX,segment_reg */
491 WORD seg = *(WORD *)INSTR_GetOperandAddr( context, instr + 1,
492 long_addr, segprefix, &len );
493 if (!(seg = INSTR_ReplaceSelector( context, seg )))
494 break; /* Unable to emulate it */
496 switch((instr[1] >> 3) & 7)
499 ES_reg(context) = seg;
500 EIP_reg(context) += prefixlen + len + 1;
505 SS_reg(context) = seg;
506 EIP_reg(context) += prefixlen + len + 1;
509 DS_reg(context) = seg;
510 EIP_reg(context) += prefixlen + len + 1;
514 FS_reg(context) = seg;
515 EIP_reg(context) += prefixlen + len + 1;
520 GS_reg(context) = seg;
521 EIP_reg(context) += prefixlen + len + 1;
529 break; /* Unable to emulate it */
531 case 0xc4: /* les addr,reg */
532 case 0xc5: /* lds addr,reg */
533 if (INSTR_EmulateLDS( context, instr, long_op,
534 long_addr, segprefix, &len ))
536 EIP_reg(context) += prefixlen + len;
539 break; /* Unable to emulate it */
541 case 0xcd: /* int <XX> */
544 fprintf(stderr, "int xx from 32-bit code is not supported.\n");
545 break; /* Unable to emulate it */
549 SEGPTR addr = INT_GetHandler( instr[1] );
550 WORD *stack = (WORD *)STACK_PTR( context );
551 /* Push the flags and return address on the stack */
552 *(--stack) = FL_reg(context);
553 *(--stack) = CS_reg(context);
554 *(--stack) = IP_reg(context) + prefixlen + 2;
555 STACK_reg(context) -= 3 * sizeof(WORD);
556 /* Jump to the interrupt handler */
557 CS_reg(context) = HIWORD(addr);
558 EIP_reg(context) = LOWORD(addr);
562 case 0xcf: /* iret */
565 DWORD *stack = (DWORD *)STACK_PTR( context );
566 EIP_reg(context) = *stack++;
567 CS_reg(context) = *stack++;
568 EFL_reg(context) = *stack;
569 STACK_reg(context) += 3*sizeof(DWORD); /* Pop the return address and flags */
573 WORD *stack = (WORD *)STACK_PTR( context );
574 EIP_reg(context) = *stack++;
575 CS_reg(context) = *stack++;
576 FL_reg(context) = *stack;
577 STACK_reg(context) += 3*sizeof(WORD); /* Pop the return address and flags */
581 case 0xe4: /* inb al,XX */
582 AL_reg(context) = inport( instr[1], 1 );
583 EIP_reg(context) += prefixlen + 2;
586 case 0xe5: /* in (e)ax,XX */
587 if (long_op) EAX_reg(context) = inport( instr[1], 4 );
588 else AX_reg(context) = inport( instr[1], 2 );
589 EIP_reg(context) += prefixlen + 2;
592 case 0xe6: /* outb XX,al */
593 outport( instr[1], 1, AL_reg(context) );
594 EIP_reg(context) += prefixlen + 2;
597 case 0xe7: /* out XX,(e)ax */
598 if (long_op) outport( instr[1], 4, EAX_reg(context) );
599 else outport( instr[1], 2, AX_reg(context) );
600 EIP_reg(context) += prefixlen + 2;
603 case 0xec: /* inb al,dx */
604 AL_reg(context) = inport( DX_reg(context), 1 );
605 EIP_reg(context) += prefixlen + 1;
608 case 0xed: /* in (e)ax,dx */
609 if (long_op) EAX_reg(context) = inport( DX_reg(context), 4 );
610 else AX_reg(context) = inport( DX_reg(context), 2 );
611 EIP_reg(context) += prefixlen + 1;
614 case 0xee: /* outb dx,al */
615 outport( DX_reg(context), 1, AL_reg(context) );
616 EIP_reg(context) += prefixlen + 1;
619 case 0xef: /* out dx,(e)ax */
620 if (long_op) outport( DX_reg(context), 4, EAX_reg(context) );
621 else outport( DX_reg(context), 2, AX_reg(context) );
622 EIP_reg(context) += prefixlen + 1;
625 case 0xfa: /* cli, ignored */
626 EIP_reg(context) += prefixlen + 1;
629 case 0xfb: /* sti, ignored */
630 EIP_reg(context) += prefixlen + 1;
633 fprintf(stderr, "Unexpected Windows program segfault"
634 " - opcode = %x\n", *instr);
635 return FALSE; /* Unable to emulate it */