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 return DOSMEM_BiosSeg;
35 return 0; /* Can't replace selector */
39 /***********************************************************************
40 * INSTR_GetOperandAddr
42 * Return the address of an instruction operand (from the mod/rm byte).
44 static BYTE *INSTR_GetOperandAddr( struct sigcontext_struct *context,
45 BYTE *instr, int long_addr,
46 int segprefix, int *len )
48 int mod, rm, base, index = 0, ss = 0, seg = 0, off;
50 #define GET_VAL(val,type) \
51 { *val = *(type *)instr; instr += sizeof(type); *len += sizeof(type); }
54 GET_VAL( &mod, BYTE );
62 case 0: return (BYTE *)&EAX_reg(context);
63 case 1: return (BYTE *)&ECX_reg(context);
64 case 2: return (BYTE *)&EDX_reg(context);
65 case 3: return (BYTE *)&EBX_reg(context);
66 case 4: return (BYTE *)&ESP_reg(context);
67 case 5: return (BYTE *)&EBP_reg(context);
68 case 6: return (BYTE *)&ESI_reg(context);
69 case 7: return (BYTE *)&EDI_reg(context);
78 GET_VAL( &sib, BYTE );
83 case 0: index = EAX_reg(context); break;
84 case 1: index = ECX_reg(context); break;
85 case 2: index = EDX_reg(context); break;
86 case 3: index = EBX_reg(context); break;
87 case 4: index = 0; break;
88 case 5: index = EBP_reg(context); break;
89 case 6: index = ESI_reg(context); break;
90 case 7: index = EDI_reg(context); break;
96 case 0: base = EAX_reg(context); seg = DS_reg(context); break;
97 case 1: base = ECX_reg(context); seg = DS_reg(context); break;
98 case 2: base = EDX_reg(context); seg = DS_reg(context); break;
99 case 3: base = EBX_reg(context); seg = DS_reg(context); break;
100 case 4: base = ESP_reg(context); seg = SS_reg(context); break;
101 case 5: base = EBP_reg(context); seg = SS_reg(context); break;
102 case 6: base = ESI_reg(context); seg = DS_reg(context); break;
103 case 7: base = EDI_reg(context); seg = DS_reg(context); break;
108 if (rm == 5) /* special case: ds:(disp32) */
110 GET_VAL( &base, DWORD );
111 seg = DS_reg(context);
115 case 1: /* 8-bit disp */
116 GET_VAL( &off, BYTE );
117 base += (signed char)off;
120 case 2: /* 32-bit disp */
121 GET_VAL( &off, DWORD );
122 base += (signed long)off;
126 else /* short address */
130 case 0: /* ds:(bx,si) */
131 base = BX_reg(context) + SI_reg(context);
132 seg = DS_reg(context);
134 case 1: /* ds:(bx,di) */
135 base = BX_reg(context) + DI_reg(context);
136 seg = DS_reg(context);
138 case 2: /* ss:(bp,si) */
139 base = BP_reg(context) + SI_reg(context);
140 seg = SS_reg(context);
142 case 3: /* ss:(bp,di) */
143 base = BP_reg(context) + DI_reg(context);
144 seg = SS_reg(context);
146 case 4: /* ds:(si) */
147 base = SI_reg(context);
148 seg = DS_reg(context);
150 case 5: /* ds:(di) */
151 base = DI_reg(context);
152 seg = DS_reg(context);
154 case 6: /* ss:(bp) */
155 base = BP_reg(context);
156 seg = SS_reg(context);
158 case 7: /* ds:(bx) */
159 base = BX_reg(context);
160 seg = DS_reg(context);
167 if (rm == 6) /* special case: ds:(disp16) */
169 GET_VAL( &base, WORD );
170 seg = DS_reg(context);
174 case 1: /* 8-bit disp */
175 GET_VAL( &off, BYTE );
176 base += (signed char)off;
179 case 2: /* 16-bit disp */
180 GET_VAL( &off, WORD );
181 base += (signed short)off;
186 if (segprefix != -1) seg = segprefix;
188 /* FIXME: should check limit of the segment here */
189 return (BYTE *)PTR_SEG_OFF_TO_LIN( seg, (base + (index << ss)) );
193 /***********************************************************************
196 * Emulate the LDS (and LES,LFS,etc.) instruction.
198 static BOOL INSTR_EmulateLDS( struct sigcontext_struct *context,
199 BYTE *instr, int long_op, int long_addr,
200 int segprefix, int *len )
202 BYTE *regmodrm = instr + 1 + (*instr == 0x0f);
203 BYTE *addr = INSTR_GetOperandAddr( context, regmodrm,
204 long_addr, segprefix, len );
205 WORD seg = *(WORD *)(addr + (long_op ? 4 : 2));
207 if (!(seg = INSTR_ReplaceSelector( context, seg )))
208 return FALSE; /* Unable to emulate it */
210 /* Now store the offset in the correct register */
212 switch((*regmodrm >> 3) & 7)
215 if (long_op) EAX_reg(context) = *(DWORD *)addr;
216 else AX_reg(context) = *(WORD *)addr;
219 if (long_op) ECX_reg(context) = *(DWORD *)addr;
220 else CX_reg(context) = *(WORD *)addr;
223 if (long_op) EDX_reg(context) = *(DWORD *)addr;
224 else DX_reg(context) = *(WORD *)addr;
227 if (long_op) EBX_reg(context) = *(DWORD *)addr;
228 else BX_reg(context) = *(WORD *)addr;
231 if (long_op) ESP_reg(context) = *(DWORD *)addr;
232 else SP_reg(context) = *(WORD *)addr;
235 if (long_op) EBP_reg(context) = *(DWORD *)addr;
236 else BP_reg(context) = *(WORD *)addr;
239 if (long_op) ESI_reg(context) = *(DWORD *)addr;
240 else SI_reg(context) = *(WORD *)addr;
243 if (long_op) EDI_reg(context) = *(DWORD *)addr;
244 else DI_reg(context) = *(WORD *)addr;
248 /* Store the correct segment in the segment register */
252 case 0xc4: ES_reg(context) = seg; break; /* les */
253 case 0xc5: DS_reg(context) = seg; break; /* lds */
254 case 0x0f: switch(instr[1])
256 case 0xb2: SS_reg(context) = seg; break; /* lss */
258 case 0xb4: FS_reg(context) = seg; break; /* lfs */
261 case 0xb5: GS_reg(context) = seg; break; /* lgs */
267 /* Add the opcode size to the total length */
269 *len += 1 + (*instr == 0x0f);
274 /***********************************************************************
275 * INSTR_EmulateInstruction
277 * Emulate a priviledged instruction. Returns TRUE if emulation successful.
279 BOOL INSTR_EmulateInstruction( struct sigcontext_struct *context )
281 int prefix, segprefix, prefixlen, len, repX, long_op, long_addr;
284 long_op = long_addr = (GET_SEL_FLAGS(CS_reg(context)) & LDT_FLAGS_32BIT) != 0;
285 instr = (BYTE *) PTR_SEG_OFF_TO_LIN( CS_reg(context), EIP_reg(context) );
287 /* First handle any possible prefix */
289 segprefix = -1; /* no prefix */
298 segprefix = CS_reg(context);
301 segprefix = SS_reg(context);
304 segprefix = DS_reg(context);
307 segprefix = ES_reg(context);
311 segprefix = FS_reg(context);
316 segprefix = GS_reg(context);
320 long_op = !long_op; /* opcode size prefix */
323 long_addr = !long_addr; /* addr size prefix */
325 case 0xf0: /* lock */
327 case 0xf2: /* repne */
330 case 0xf3: /* repe */
334 prefix = 0; /* no more prefixes */
344 /* Now look at the actual instruction */
348 case 0x07: /* pop es */
349 case 0x17: /* pop ss */
350 case 0x1f: /* pop ds */
352 WORD seg = *(WORD *)STACK_PTR( context );
353 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
357 case 0x07: ES_reg(context) = seg; break;
358 case 0x17: SS_reg(context) = seg; break;
359 case 0x1f: DS_reg(context) = seg; break;
361 STACK_reg(context) += long_op ? 4 : 2;
362 EIP_reg(context) += prefixlen + 1;
366 break; /* Unable to emulate it */
368 case 0x0f: /* extended instruction */
372 case 0xa1: /* pop fs */
374 WORD seg = *(WORD *)STACK_PTR( context );
375 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
377 FS_reg(context) = seg;
378 STACK_reg(context) += long_op ? 4 : 2;
379 EIP_reg(context) += prefixlen + 2;
387 case 0xa9: /* pop gs */
389 WORD seg = *(WORD *)STACK_PTR( context );
390 if ((seg = INSTR_ReplaceSelector( context, seg )) != 0)
392 GS_reg(context) = seg;
393 STACK_reg(context) += long_op ? 4 : 2;
394 EIP_reg(context) += prefixlen + 2;
401 case 0xb2: /* lss addr,reg */
403 case 0xb4: /* lfs addr,reg */
406 case 0xb5: /* lgs addr,reg */
408 if (INSTR_EmulateLDS( context, instr, long_op,
409 long_addr, segprefix, &len ))
411 EIP_reg(context) += prefixlen + len;
416 break; /* Unable to emulate it */
418 case 0x6c: /* insb */
419 case 0x6d: /* insw/d */
420 case 0x6e: /* outsb */
421 case 0x6f: /* outsw/d */
423 int typ = *instr; /* Just in case it's overwritten. */
424 int outp = (typ >= 0x6e);
425 unsigned long count = repX ?
426 (long_addr ? ECX_reg(context) : CX_reg(context)) : 1;
427 int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
428 int step = (EFL_reg(context) & 0x400) ? -opsize : +opsize;
429 int seg = outp ? DS_reg(context) : ES_reg(context); /* FIXME: is this right? */
432 /* FIXME: Check segment readable. */
435 /* FIXME: Check segment writeable. */
440 ECX_reg(context) = 0;
449 data = PTR_SEG_OFF_TO_LIN (seg,
450 long_addr ? ESI_reg(context) : SI_reg(context));
451 if (long_addr) ESI_reg(context) += step;
452 else SI_reg(context) += step;
456 data = PTR_SEG_OFF_TO_LIN (seg,
457 long_addr ? EDI_reg(context) : DI_reg(context));
458 if (long_addr) EDI_reg(context) += step;
459 else DI_reg(context) += step;
465 *((BYTE *)data) = inport( DX_reg(context), 1);
469 *((DWORD *)data) = inport( DX_reg(context), 4);
471 *((WORD *)data) = inport( DX_reg(context), 2);
474 outport( DX_reg(context), 1, *((BYTE *)data));
478 outport( DX_reg(context), 4, *((DWORD *)data));
480 outport( DX_reg(context), 2, *((WORD *)data));
484 EIP_reg(context) += prefixlen + 1;
488 case 0x8e: /* mov XX,segment_reg */
490 WORD seg = *(WORD *)INSTR_GetOperandAddr( context, instr + 1,
491 long_addr, segprefix, &len );
492 if (!(seg = INSTR_ReplaceSelector( context, seg )))
493 break; /* Unable to emulate it */
495 switch((instr[1] >> 3) & 7)
498 ES_reg(context) = seg;
499 EIP_reg(context) += prefixlen + len + 1;
504 SS_reg(context) = seg;
505 EIP_reg(context) += prefixlen + len + 1;
508 DS_reg(context) = seg;
509 EIP_reg(context) += prefixlen + len + 1;
513 FS_reg(context) = seg;
514 EIP_reg(context) += prefixlen + len + 1;
519 GS_reg(context) = seg;
520 EIP_reg(context) += prefixlen + len + 1;
528 break; /* Unable to emulate it */
530 case 0xc4: /* les addr,reg */
531 case 0xc5: /* lds addr,reg */
532 if (INSTR_EmulateLDS( context, instr, long_op,
533 long_addr, segprefix, &len ))
535 EIP_reg(context) += prefixlen + len;
538 break; /* Unable to emulate it */
540 case 0xcd: /* int <XX> */
543 fprintf(stderr, "int xx from 32-bit code is not supported.\n");
544 break; /* Unable to emulate it */
548 SEGPTR addr = INT_GetHandler( instr[1] );
549 WORD *stack = (WORD *)STACK_PTR( context );
550 /* Push the flags and return address on the stack */
551 *(--stack) = FL_reg(context);
552 *(--stack) = CS_reg(context);
553 *(--stack) = IP_reg(context) + prefixlen + 2;
554 STACK_reg(context) -= 3 * sizeof(WORD);
555 /* Jump to the interrupt handler */
556 CS_reg(context) = HIWORD(addr);
557 EIP_reg(context) = LOWORD(addr);
561 case 0xcf: /* iret */
564 DWORD *stack = (DWORD *)STACK_PTR( context );
565 EIP_reg(context) = *stack++;
566 CS_reg(context) = *stack++;
567 EFL_reg(context) = *stack;
568 STACK_reg(context) += 3*sizeof(DWORD); /* Pop the return address and flags */
572 WORD *stack = (WORD *)STACK_PTR( context );
573 EIP_reg(context) = *stack++;
574 CS_reg(context) = *stack++;
575 FL_reg(context) = *stack;
576 STACK_reg(context) += 3*sizeof(WORD); /* Pop the return address and flags */
580 case 0xe4: /* inb al,XX */
581 AL_reg(context) = inport( instr[1], 1 );
582 EIP_reg(context) += prefixlen + 2;
585 case 0xe5: /* in (e)ax,XX */
586 if (long_op) EAX_reg(context) = inport( instr[1], 4 );
587 else AX_reg(context) = inport( instr[1], 2 );
588 EIP_reg(context) += prefixlen + 2;
591 case 0xe6: /* outb XX,al */
592 outport( instr[1], 1, AL_reg(context) );
593 EIP_reg(context) += prefixlen + 2;
596 case 0xe7: /* out XX,(e)ax */
597 if (long_op) outport( instr[1], 4, EAX_reg(context) );
598 else outport( instr[1], 2, AX_reg(context) );
599 EIP_reg(context) += prefixlen + 2;
602 case 0xec: /* inb al,dx */
603 AL_reg(context) = inport( DX_reg(context), 1 );
604 EIP_reg(context) += prefixlen + 1;
607 case 0xed: /* in (e)ax,dx */
608 if (long_op) EAX_reg(context) = inport( DX_reg(context), 4 );
609 else AX_reg(context) = inport( DX_reg(context), 2 );
610 EIP_reg(context) += prefixlen + 1;
613 case 0xee: /* outb dx,al */
614 outport( DX_reg(context), 1, AL_reg(context) );
615 EIP_reg(context) += prefixlen + 1;
618 case 0xef: /* out dx,(e)ax */
619 if (long_op) outport( DX_reg(context), 4, EAX_reg(context) );
620 else outport( DX_reg(context), 2, AX_reg(context) );
621 EIP_reg(context) += prefixlen + 1;
624 case 0xfa: /* cli, ignored */
625 EIP_reg(context) += prefixlen + 1;
628 case 0xfb: /* sti, ignored */
629 EIP_reg(context) += prefixlen + 1;
632 fprintf(stderr, "Unexpected Windows program segfault"
633 " - opcode = %x\n", *instr);
634 return FALSE; /* Unable to emulate it */