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1
/*
2
 *  vm86 linux syscall support
3
 * 
4
 *  Copyright (c) 2003 Fabrice Bellard
5
 *
6
 *  This program is free software; you can redistribute it and/or modify
7
 *  it under the terms of the GNU General Public License as published by
8
 *  the Free Software Foundation; either version 2 of the License, or
9
 *  (at your option) any later version.
10
 *
11
 *  This program is distributed in the hope that it will be useful,
12
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14
 *  GNU General Public License for more details.
15
 *
16
 *  You should have received a copy of the GNU General Public License
17
 *  along with this program; if not, write to the Free Software
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 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19
 */
20
#include <stdlib.h>
21
#include <stdio.h>
22
#include <stdarg.h>
23
#include <string.h>
24
#include <errno.h>
25
#include <unistd.h>
26

    
27
#include "qemu.h"
28

    
29
//#define DEBUG_VM86
30

    
31
#define set_flags(X,new,mask) \
32
((X) = ((X) & ~(mask)) | ((new) & (mask)))
33

    
34
#define SAFE_MASK        (0xDD5)
35
#define RETURN_MASK        (0xDFF)
36

    
37
static inline int is_revectored(int nr, struct target_revectored_struct *bitmap)
38
{
39
    return (((uint8_t *)bitmap)[nr >> 3] >> (nr & 7)) & 1;
40
}
41

    
42
static inline void vm_putw(uint8_t *segptr, unsigned int reg16, unsigned int val)
43
{
44
    *(uint16_t *)(segptr + (reg16 & 0xffff)) = tswap16(val);
45
}
46

    
47
static inline void vm_putl(uint8_t *segptr, unsigned int reg16, unsigned int val)
48
{
49
    *(uint32_t *)(segptr + (reg16 & 0xffff)) = tswap32(val);
50
}
51

    
52
static inline unsigned int vm_getw(uint8_t *segptr, unsigned int reg16)
53
{
54
    return tswap16(*(uint16_t *)(segptr + (reg16 & 0xffff)));
55
}
56

    
57
static inline unsigned int vm_getl(uint8_t *segptr, unsigned int reg16)
58
{
59
    return tswap32(*(uint16_t *)(segptr + (reg16 & 0xffff)));
60
}
61

    
62
void save_v86_state(CPUX86State *env)
63
{
64
    TaskState *ts = env->opaque;
65

    
66
    /* put the VM86 registers in the userspace register structure */
67
    ts->target_v86->regs.eax = tswap32(env->regs[R_EAX]);
68
    ts->target_v86->regs.ebx = tswap32(env->regs[R_EBX]);
69
    ts->target_v86->regs.ecx = tswap32(env->regs[R_ECX]);
70
    ts->target_v86->regs.edx = tswap32(env->regs[R_EDX]);
71
    ts->target_v86->regs.esi = tswap32(env->regs[R_ESI]);
72
    ts->target_v86->regs.edi = tswap32(env->regs[R_EDI]);
73
    ts->target_v86->regs.ebp = tswap32(env->regs[R_EBP]);
74
    ts->target_v86->regs.esp = tswap32(env->regs[R_ESP]);
75
    ts->target_v86->regs.eip = tswap32(env->eip);
76
    ts->target_v86->regs.cs = tswap16(env->segs[R_CS]);
77
    ts->target_v86->regs.ss = tswap16(env->segs[R_SS]);
78
    ts->target_v86->regs.ds = tswap16(env->segs[R_DS]);
79
    ts->target_v86->regs.es = tswap16(env->segs[R_ES]);
80
    ts->target_v86->regs.fs = tswap16(env->segs[R_FS]);
81
    ts->target_v86->regs.gs = tswap16(env->segs[R_GS]);
82
    set_flags(env->eflags, ts->v86flags, VIF_MASK | ts->v86mask);
83
    ts->target_v86->regs.eflags = tswap32(env->eflags);
84
#ifdef DEBUG_VM86
85
    fprintf(logfile, "save_v86_state: eflags=%08x cs:ip=%04x:%04x\n", 
86
            env->eflags, env->segs[R_CS], env->eip);
87
#endif
88

    
89
    /* restore 32 bit registers */
90
    env->regs[R_EAX] = ts->vm86_saved_regs.eax;
91
    env->regs[R_EBX] = ts->vm86_saved_regs.ebx;
92
    env->regs[R_ECX] = ts->vm86_saved_regs.ecx;
93
    env->regs[R_EDX] = ts->vm86_saved_regs.edx;
94
    env->regs[R_ESI] = ts->vm86_saved_regs.esi;
95
    env->regs[R_EDI] = ts->vm86_saved_regs.edi;
96
    env->regs[R_EBP] = ts->vm86_saved_regs.ebp;
97
    env->regs[R_ESP] = ts->vm86_saved_regs.esp;
98
    env->eflags = ts->vm86_saved_regs.eflags;
99
    env->eip = ts->vm86_saved_regs.eip;
100

    
101
    cpu_x86_load_seg(env, R_CS, ts->vm86_saved_regs.cs);
102
    cpu_x86_load_seg(env, R_SS, ts->vm86_saved_regs.ss);
103
    cpu_x86_load_seg(env, R_DS, ts->vm86_saved_regs.ds);
104
    cpu_x86_load_seg(env, R_ES, ts->vm86_saved_regs.es);
105
    cpu_x86_load_seg(env, R_FS, ts->vm86_saved_regs.fs);
106
    cpu_x86_load_seg(env, R_GS, ts->vm86_saved_regs.gs);
107
}
108

    
109
/* return from vm86 mode to 32 bit. The vm86() syscall will return
110
   'retval' */
111
static inline void return_to_32bit(CPUX86State *env, int retval)
112
{
113
#ifdef DEBUG_VM86
114
    fprintf(logfile, "return_to_32bit: ret=0x%x\n", retval);
115
#endif
116
    save_v86_state(env);
117
    env->regs[R_EAX] = retval;
118
}
119

    
120
static inline int set_IF(CPUX86State *env)
121
{
122
    TaskState *ts = env->opaque;
123
    
124
    ts->v86flags |= VIF_MASK;
125
    if (ts->v86flags & VIP_MASK) {
126
        return_to_32bit(env, TARGET_VM86_STI);
127
        return 1;
128
    }
129
    return 0;
130
}
131

    
132
static inline void clear_IF(CPUX86State *env)
133
{
134
    TaskState *ts = env->opaque;
135

    
136
    ts->v86flags &= ~VIF_MASK;
137
}
138

    
139
static inline void clear_TF(CPUX86State *env)
140
{
141
    env->eflags &= ~TF_MASK;
142
}
143

    
144
static inline void clear_AC(CPUX86State *env)
145
{
146
    env->eflags &= ~AC_MASK;
147
}
148

    
149
static inline int set_vflags_long(unsigned long eflags, CPUX86State *env)
150
{
151
    TaskState *ts = env->opaque;
152

    
153
    set_flags(ts->v86flags, eflags, ts->v86mask);
154
    set_flags(env->eflags, eflags, SAFE_MASK);
155
    if (eflags & IF_MASK)
156
        return set_IF(env);
157
    else
158
        clear_IF(env);
159
    return 0;
160
}
161

    
162
static inline int set_vflags_short(unsigned short flags, CPUX86State *env)
163
{
164
    TaskState *ts = env->opaque;
165

    
166
    set_flags(ts->v86flags, flags, ts->v86mask & 0xffff);
167
    set_flags(env->eflags, flags, SAFE_MASK);
168
    if (flags & IF_MASK)
169
        return set_IF(env);
170
    else
171
        clear_IF(env);
172
    return 0;
173
}
174

    
175
static inline unsigned int get_vflags(CPUX86State *env)
176
{
177
    TaskState *ts = env->opaque;
178
    unsigned int flags;
179

    
180
    flags = env->eflags & RETURN_MASK;
181
    if (ts->v86flags & VIF_MASK)
182
        flags |= IF_MASK;
183
    return flags | (ts->v86flags & ts->v86mask);
184
}
185

    
186
#define ADD16(reg, val) reg = (reg & ~0xffff) | ((reg + (val)) & 0xffff)
187

    
188
/* handle VM86 interrupt (NOTE: the CPU core currently does not
189
   support TSS interrupt revectoring, so this code is always executed) */
190
static void do_int(CPUX86State *env, int intno)
191
{
192
    TaskState *ts = env->opaque;
193
    uint32_t *int_ptr, segoffs;
194
    uint8_t *ssp;
195
    unsigned int sp;
196

    
197
    if (env->segs[R_CS] == TARGET_BIOSSEG)
198
        goto cannot_handle;
199
    if (is_revectored(intno, &ts->vm86plus.int_revectored))
200
        goto cannot_handle;
201
    if (intno == 0x21 && is_revectored((env->regs[R_EAX] >> 8) & 0xff, 
202
                                       &ts->vm86plus.int21_revectored))
203
        goto cannot_handle;
204
    int_ptr = (uint32_t *)(intno << 2);
205
    segoffs = tswap32(*int_ptr);
206
    if ((segoffs >> 16) == TARGET_BIOSSEG)
207
        goto cannot_handle;
208
#if defined(DEBUG_VM86)
209
    fprintf(logfile, "VM86: emulating int 0x%x. CS:IP=%04x:%04x\n", 
210
            intno, segoffs >> 16, segoffs & 0xffff);
211
#endif
212
    /* save old state */
213
    ssp = (uint8_t *)(env->segs[R_SS] << 4);
214
    sp = env->regs[R_ESP] & 0xffff;
215
    vm_putw(ssp, sp - 2, get_vflags(env));
216
    vm_putw(ssp, sp - 4, env->segs[R_CS]);
217
    vm_putw(ssp, sp - 6, env->eip);
218
    ADD16(env->regs[R_ESP], -6);
219
    /* goto interrupt handler */
220
    env->eip = segoffs & 0xffff;
221
    cpu_x86_load_seg(env, R_CS, segoffs >> 16);
222
    clear_TF(env);
223
    clear_IF(env);
224
    clear_AC(env);
225
    return;
226
 cannot_handle:
227
#if defined(DEBUG_VM86)
228
    fprintf(logfile, "VM86: return to 32 bits int 0x%x\n", intno);
229
#endif
230
    return_to_32bit(env, TARGET_VM86_INTx | (intno << 8));
231
}
232

    
233
void handle_vm86_trap(CPUX86State *env, int trapno)
234
{
235
    if (trapno == 1 || trapno == 3) {
236
        return_to_32bit(env, TARGET_VM86_TRAP + (trapno << 8));
237
    } else {
238
        do_int(env, trapno);
239
    }
240
}
241

    
242
#define CHECK_IF_IN_TRAP() \
243
      if ((ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) && \
244
          (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_TFpendig)) \
245
                newflags |= TF_MASK
246

    
247
#define VM86_FAULT_RETURN \
248
        if ((ts->vm86plus.vm86plus.flags & TARGET_force_return_for_pic) && \
249
            (ts->v86flags & (IF_MASK | VIF_MASK))) \
250
            return_to_32bit(env, TARGET_VM86_PICRETURN); \
251
        return
252

    
253
void handle_vm86_fault(CPUX86State *env)
254
{
255
    TaskState *ts = env->opaque;
256
    uint8_t *csp, *pc, *ssp;
257
    unsigned int ip, sp, newflags, newip, newcs, opcode, intno;
258
    int data32, pref_done;
259

    
260
    csp = (uint8_t *)(env->segs[R_CS] << 4);
261
    ip = env->eip & 0xffff;
262
    pc = csp + ip;
263
    
264
    ssp = (uint8_t *)(env->segs[R_SS] << 4);
265
    sp = env->regs[R_ESP] & 0xffff;
266

    
267
#if defined(DEBUG_VM86)
268
    fprintf(logfile, "VM86 exception %04x:%08x %02x %02x\n",
269
            env->segs[R_CS], env->eip, pc[0], pc[1]);
270
#endif
271

    
272
    data32 = 0;
273
    pref_done = 0;
274
    do {
275
        opcode = csp[ip];
276
        ADD16(ip, 1);
277
        switch (opcode) {
278
        case 0x66:      /* 32-bit data */     data32=1; break;
279
        case 0x67:      /* 32-bit address */  break;
280
        case 0x2e:      /* CS */              break;
281
        case 0x3e:      /* DS */              break;
282
        case 0x26:      /* ES */              break;
283
        case 0x36:      /* SS */              break;
284
        case 0x65:      /* GS */              break;
285
        case 0x64:      /* FS */              break;
286
        case 0xf2:      /* repnz */              break;
287
        case 0xf3:      /* rep */             break;
288
        default: pref_done = 1;
289
        }
290
    } while (!pref_done);
291

    
292
    /* VM86 mode */
293
    switch(opcode) {
294
    case 0x9c: /* pushf */
295
        ADD16(env->eip, 2);
296
        if (data32) {
297
            vm_putl(ssp, sp - 4, get_vflags(env));
298
            ADD16(env->regs[R_ESP], -4);
299
        } else {
300
            vm_putw(ssp, sp - 2, get_vflags(env));
301
            ADD16(env->regs[R_ESP], -2);
302
        }
303
        env->eip = ip;
304
        VM86_FAULT_RETURN;
305

    
306
    case 0x9d: /* popf */
307
        if (data32) {
308
            newflags = vm_getl(ssp, sp);
309
            ADD16(env->regs[R_ESP], 4);
310
        } else {
311
            newflags = vm_getw(ssp, sp);
312
            ADD16(env->regs[R_ESP], 2);
313
        }
314
        env->eip = ip;
315
        CHECK_IF_IN_TRAP();
316
        if (data32) {
317
            if (set_vflags_long(newflags, env))
318
                return;
319
        } else {
320
            if (set_vflags_short(newflags, env))
321
                return;
322
        }
323
        VM86_FAULT_RETURN;
324

    
325
    case 0xcd: /* int */
326
        intno = csp[ip];
327
        ADD16(ip, 1);
328
        env->eip = ip;
329
        if (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) {
330
            if ( (ts->vm86plus.vm86plus.vm86dbg_intxxtab[intno >> 3] >> 
331
                  (intno &7)) & 1) {
332
                return_to_32bit(env, TARGET_VM86_INTx + (intno << 8));
333
                return;
334
            }
335
        }
336
        do_int(env, intno);
337
        break;
338

    
339
    case 0xcf: /* iret */
340
        if (data32) {
341
            newip = vm_getl(ssp, sp) & 0xffff;
342
            newcs = vm_getl(ssp, sp + 4) & 0xffff;
343
            newflags = vm_getl(ssp, sp + 8);
344
            ADD16(env->regs[R_ESP], 12);
345
        } else {
346
            newip = vm_getw(ssp, sp);
347
            newcs = vm_getw(ssp, sp + 2);
348
            newflags = vm_getw(ssp, sp + 4);
349
            ADD16(env->regs[R_ESP], 6);
350
        }
351
        env->eip = newip;
352
        cpu_x86_load_seg(env, R_CS, newcs);
353
        CHECK_IF_IN_TRAP();
354
        if (data32) {
355
            if (set_vflags_long(newflags, env))
356
                return;
357
        } else {
358
            if (set_vflags_short(newflags, env))
359
                return;
360
        }
361
        VM86_FAULT_RETURN;
362
        
363
    case 0xfa: /* cli */
364
        env->eip = ip;
365
        clear_IF(env);
366
        VM86_FAULT_RETURN;
367
        
368
    case 0xfb: /* sti */
369
        env->eip = ip;
370
        if (set_IF(env))
371
            return;
372
        VM86_FAULT_RETURN;
373

    
374
    default:
375
        /* real VM86 GPF exception */
376
        return_to_32bit(env, TARGET_VM86_UNKNOWN);
377
        break;
378
    }
379
}
380

    
381
int do_vm86(CPUX86State *env, long subfunction, 
382
            struct target_vm86plus_struct * target_v86)
383
{
384
    TaskState *ts = env->opaque;
385
    int ret;
386
    
387
    switch (subfunction) {
388
    case TARGET_VM86_REQUEST_IRQ:
389
    case TARGET_VM86_FREE_IRQ:
390
    case TARGET_VM86_GET_IRQ_BITS:
391
    case TARGET_VM86_GET_AND_RESET_IRQ:
392
        gemu_log("qemu: unsupported vm86 subfunction (%ld)\n", subfunction);
393
        ret = -EINVAL;
394
        goto out;
395
    case TARGET_VM86_PLUS_INSTALL_CHECK:
396
        /* NOTE: on old vm86 stuff this will return the error
397
           from verify_area(), because the subfunction is
398
           interpreted as (invalid) address to vm86_struct.
399
           So the installation check works.
400
            */
401
        ret = 0;
402
        goto out;
403
    }
404

    
405
    ts->target_v86 = target_v86;
406
    /* save current CPU regs */
407
    ts->vm86_saved_regs.eax = 0; /* default vm86 syscall return code */
408
    ts->vm86_saved_regs.ebx = env->regs[R_EBX];
409
    ts->vm86_saved_regs.ecx = env->regs[R_ECX];
410
    ts->vm86_saved_regs.edx = env->regs[R_EDX];
411
    ts->vm86_saved_regs.esi = env->regs[R_ESI];
412
    ts->vm86_saved_regs.edi = env->regs[R_EDI];
413
    ts->vm86_saved_regs.ebp = env->regs[R_EBP];
414
    ts->vm86_saved_regs.esp = env->regs[R_ESP];
415
    ts->vm86_saved_regs.eflags = env->eflags;
416
    ts->vm86_saved_regs.eip  = env->eip;
417
    ts->vm86_saved_regs.cs = env->segs[R_CS];
418
    ts->vm86_saved_regs.ss = env->segs[R_SS];
419
    ts->vm86_saved_regs.ds = env->segs[R_DS];
420
    ts->vm86_saved_regs.es = env->segs[R_ES];
421
    ts->vm86_saved_regs.fs = env->segs[R_FS];
422
    ts->vm86_saved_regs.gs = env->segs[R_GS];
423

    
424
    /* build vm86 CPU state */
425
    ts->v86flags = tswap32(target_v86->regs.eflags);
426
    env->eflags = (env->eflags & ~SAFE_MASK) | 
427
        (tswap32(target_v86->regs.eflags) & SAFE_MASK) | VM_MASK;
428

    
429
    ts->vm86plus.cpu_type = tswapl(target_v86->cpu_type);
430
    switch (ts->vm86plus.cpu_type) {
431
    case TARGET_CPU_286:
432
        ts->v86mask = 0;
433
        break;
434
    case TARGET_CPU_386:
435
        ts->v86mask = NT_MASK | IOPL_MASK;
436
        break;
437
    case TARGET_CPU_486:
438
        ts->v86mask = AC_MASK | NT_MASK | IOPL_MASK;
439
        break;
440
    default:
441
        ts->v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
442
        break;
443
    }
444

    
445
    env->regs[R_EBX] = tswap32(target_v86->regs.ebx);
446
    env->regs[R_ECX] = tswap32(target_v86->regs.ecx);
447
    env->regs[R_EDX] = tswap32(target_v86->regs.edx);
448
    env->regs[R_ESI] = tswap32(target_v86->regs.esi);
449
    env->regs[R_EDI] = tswap32(target_v86->regs.edi);
450
    env->regs[R_EBP] = tswap32(target_v86->regs.ebp);
451
    env->regs[R_ESP] = tswap32(target_v86->regs.esp);
452
    env->eip = tswap32(target_v86->regs.eip);
453
    cpu_x86_load_seg(env, R_CS, tswap16(target_v86->regs.cs));
454
    cpu_x86_load_seg(env, R_SS, tswap16(target_v86->regs.ss));
455
    cpu_x86_load_seg(env, R_DS, tswap16(target_v86->regs.ds));
456
    cpu_x86_load_seg(env, R_ES, tswap16(target_v86->regs.es));
457
    cpu_x86_load_seg(env, R_FS, tswap16(target_v86->regs.fs));
458
    cpu_x86_load_seg(env, R_GS, tswap16(target_v86->regs.gs));
459
    ret = tswap32(target_v86->regs.eax); /* eax will be restored at
460
                                            the end of the syscall */
461
    memcpy(&ts->vm86plus.int_revectored, 
462
           &target_v86->int_revectored, 32);
463
    memcpy(&ts->vm86plus.int21_revectored, 
464
           &target_v86->int21_revectored, 32);
465
    ts->vm86plus.vm86plus.flags = tswapl(target_v86->vm86plus.flags);
466
    memcpy(&ts->vm86plus.vm86plus.vm86dbg_intxxtab, 
467
           target_v86->vm86plus.vm86dbg_intxxtab, 32);
468
    
469
#ifdef DEBUG_VM86
470
    fprintf(logfile, "do_vm86: cs:ip=%04x:%04x\n", env->segs[R_CS], env->eip);
471
#endif
472
    /* now the virtual CPU is ready for vm86 execution ! */
473
 out:
474
    return ret;
475
}
476