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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., 51 Franklin Street - Fifth Floor, Boston,
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 *  MA 02110-1301, USA.
20
 */
21
#include <stdlib.h>
22
#include <stdio.h>
23
#include <stdarg.h>
24
#include <string.h>
25
#include <errno.h>
26
#include <unistd.h>
27

    
28
#include "qemu.h"
29

    
30
//#define DEBUG_VM86
31

    
32
#ifdef DEBUG_VM86
33
#  define LOG_VM86(...) fprintf(logfile, ## __VA_ARGS__);
34
#else
35
#  define LOG_VM86(...) do { } while (0)
36
#endif
37

    
38

    
39
#define set_flags(X,new,mask) \
40
((X) = ((X) & ~(mask)) | ((new) & (mask)))
41

    
42
#define SAFE_MASK        (0xDD5)
43
#define RETURN_MASK        (0xDFF)
44

    
45
static inline int is_revectored(int nr, struct target_revectored_struct *bitmap)
46
{
47
    return (((uint8_t *)bitmap)[nr >> 3] >> (nr & 7)) & 1;
48
}
49

    
50
static inline void vm_putw(uint32_t segptr, unsigned int reg16, unsigned int val)
51
{
52
    stw(segptr + (reg16 & 0xffff), val);
53
}
54

    
55
static inline void vm_putl(uint32_t segptr, unsigned int reg16, unsigned int val)
56
{
57
    stl(segptr + (reg16 & 0xffff), val);
58
}
59

    
60
static inline unsigned int vm_getb(uint32_t segptr, unsigned int reg16)
61
{
62
    return ldub(segptr + (reg16 & 0xffff));
63
}
64

    
65
static inline unsigned int vm_getw(uint32_t segptr, unsigned int reg16)
66
{
67
    return lduw(segptr + (reg16 & 0xffff));
68
}
69

    
70
static inline unsigned int vm_getl(uint32_t segptr, unsigned int reg16)
71
{
72
    return ldl(segptr + (reg16 & 0xffff));
73
}
74

    
75
void save_v86_state(CPUX86State *env)
76
{
77
    TaskState *ts = env->opaque;
78
    struct target_vm86plus_struct * target_v86;
79

    
80
    if (!lock_user_struct(VERIFY_WRITE, target_v86, ts->target_v86, 0))
81
        /* FIXME - should return an error */
82
        return;
83
    /* put the VM86 registers in the userspace register structure */
84
    target_v86->regs.eax = tswap32(env->regs[R_EAX]);
85
    target_v86->regs.ebx = tswap32(env->regs[R_EBX]);
86
    target_v86->regs.ecx = tswap32(env->regs[R_ECX]);
87
    target_v86->regs.edx = tswap32(env->regs[R_EDX]);
88
    target_v86->regs.esi = tswap32(env->regs[R_ESI]);
89
    target_v86->regs.edi = tswap32(env->regs[R_EDI]);
90
    target_v86->regs.ebp = tswap32(env->regs[R_EBP]);
91
    target_v86->regs.esp = tswap32(env->regs[R_ESP]);
92
    target_v86->regs.eip = tswap32(env->eip);
93
    target_v86->regs.cs = tswap16(env->segs[R_CS].selector);
94
    target_v86->regs.ss = tswap16(env->segs[R_SS].selector);
95
    target_v86->regs.ds = tswap16(env->segs[R_DS].selector);
96
    target_v86->regs.es = tswap16(env->segs[R_ES].selector);
97
    target_v86->regs.fs = tswap16(env->segs[R_FS].selector);
98
    target_v86->regs.gs = tswap16(env->segs[R_GS].selector);
99
    set_flags(env->eflags, ts->v86flags, VIF_MASK | ts->v86mask);
100
    target_v86->regs.eflags = tswap32(env->eflags);
101
    unlock_user_struct(target_v86, ts->target_v86, 1);
102
    LOG_VM86("save_v86_state: eflags=%08x cs:ip=%04x:%04x\n",
103
             env->eflags, env->segs[R_CS].selector, env->eip);
104

    
105
    /* restore 32 bit registers */
106
    env->regs[R_EAX] = ts->vm86_saved_regs.eax;
107
    env->regs[R_EBX] = ts->vm86_saved_regs.ebx;
108
    env->regs[R_ECX] = ts->vm86_saved_regs.ecx;
109
    env->regs[R_EDX] = ts->vm86_saved_regs.edx;
110
    env->regs[R_ESI] = ts->vm86_saved_regs.esi;
111
    env->regs[R_EDI] = ts->vm86_saved_regs.edi;
112
    env->regs[R_EBP] = ts->vm86_saved_regs.ebp;
113
    env->regs[R_ESP] = ts->vm86_saved_regs.esp;
114
    env->eflags = ts->vm86_saved_regs.eflags;
115
    env->eip = ts->vm86_saved_regs.eip;
116

    
117
    cpu_x86_load_seg(env, R_CS, ts->vm86_saved_regs.cs);
118
    cpu_x86_load_seg(env, R_SS, ts->vm86_saved_regs.ss);
119
    cpu_x86_load_seg(env, R_DS, ts->vm86_saved_regs.ds);
120
    cpu_x86_load_seg(env, R_ES, ts->vm86_saved_regs.es);
121
    cpu_x86_load_seg(env, R_FS, ts->vm86_saved_regs.fs);
122
    cpu_x86_load_seg(env, R_GS, ts->vm86_saved_regs.gs);
123
}
124

    
125
/* return from vm86 mode to 32 bit. The vm86() syscall will return
126
   'retval' */
127
static inline void return_to_32bit(CPUX86State *env, int retval)
128
{
129
    LOG_VM86("return_to_32bit: ret=0x%x\n", retval);
130
    save_v86_state(env);
131
    env->regs[R_EAX] = retval;
132
}
133

    
134
static inline int set_IF(CPUX86State *env)
135
{
136
    TaskState *ts = env->opaque;
137

    
138
    ts->v86flags |= VIF_MASK;
139
    if (ts->v86flags & VIP_MASK) {
140
        return_to_32bit(env, TARGET_VM86_STI);
141
        return 1;
142
    }
143
    return 0;
144
}
145

    
146
static inline void clear_IF(CPUX86State *env)
147
{
148
    TaskState *ts = env->opaque;
149

    
150
    ts->v86flags &= ~VIF_MASK;
151
}
152

    
153
static inline void clear_TF(CPUX86State *env)
154
{
155
    env->eflags &= ~TF_MASK;
156
}
157

    
158
static inline void clear_AC(CPUX86State *env)
159
{
160
    env->eflags &= ~AC_MASK;
161
}
162

    
163
static inline int set_vflags_long(unsigned long eflags, CPUX86State *env)
164
{
165
    TaskState *ts = env->opaque;
166

    
167
    set_flags(ts->v86flags, eflags, ts->v86mask);
168
    set_flags(env->eflags, eflags, SAFE_MASK);
169
    if (eflags & IF_MASK)
170
        return set_IF(env);
171
    else
172
        clear_IF(env);
173
    return 0;
174
}
175

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

    
180
    set_flags(ts->v86flags, flags, ts->v86mask & 0xffff);
181
    set_flags(env->eflags, flags, SAFE_MASK);
182
    if (flags & IF_MASK)
183
        return set_IF(env);
184
    else
185
        clear_IF(env);
186
    return 0;
187
}
188

    
189
static inline unsigned int get_vflags(CPUX86State *env)
190
{
191
    TaskState *ts = env->opaque;
192
    unsigned int flags;
193

    
194
    flags = env->eflags & RETURN_MASK;
195
    if (ts->v86flags & VIF_MASK)
196
        flags |= IF_MASK;
197
    flags |= IOPL_MASK;
198
    return flags | (ts->v86flags & ts->v86mask);
199
}
200

    
201
#define ADD16(reg, val) reg = (reg & ~0xffff) | ((reg + (val)) & 0xffff)
202

    
203
/* handle VM86 interrupt (NOTE: the CPU core currently does not
204
   support TSS interrupt revectoring, so this code is always executed) */
205
static void do_int(CPUX86State *env, int intno)
206
{
207
    TaskState *ts = env->opaque;
208
    uint32_t int_addr, segoffs, ssp;
209
    unsigned int sp;
210

    
211
    if (env->segs[R_CS].selector == TARGET_BIOSSEG)
212
        goto cannot_handle;
213
    if (is_revectored(intno, &ts->vm86plus.int_revectored))
214
        goto cannot_handle;
215
    if (intno == 0x21 && is_revectored((env->regs[R_EAX] >> 8) & 0xff,
216
                                       &ts->vm86plus.int21_revectored))
217
        goto cannot_handle;
218
    int_addr = (intno << 2);
219
    segoffs = ldl(int_addr);
220
    if ((segoffs >> 16) == TARGET_BIOSSEG)
221
        goto cannot_handle;
222
    LOG_VM86("VM86: emulating int 0x%x. CS:IP=%04x:%04x\n",
223
             intno, segoffs >> 16, segoffs & 0xffff);
224
    /* save old state */
225
    ssp = env->segs[R_SS].selector << 4;
226
    sp = env->regs[R_ESP] & 0xffff;
227
    vm_putw(ssp, sp - 2, get_vflags(env));
228
    vm_putw(ssp, sp - 4, env->segs[R_CS].selector);
229
    vm_putw(ssp, sp - 6, env->eip);
230
    ADD16(env->regs[R_ESP], -6);
231
    /* goto interrupt handler */
232
    env->eip = segoffs & 0xffff;
233
    cpu_x86_load_seg(env, R_CS, segoffs >> 16);
234
    clear_TF(env);
235
    clear_IF(env);
236
    clear_AC(env);
237
    return;
238
 cannot_handle:
239
    LOG_VM86("VM86: return to 32 bits int 0x%x\n", intno);
240
    return_to_32bit(env, TARGET_VM86_INTx | (intno << 8));
241
}
242

    
243
void handle_vm86_trap(CPUX86State *env, int trapno)
244
{
245
    if (trapno == 1 || trapno == 3) {
246
        return_to_32bit(env, TARGET_VM86_TRAP + (trapno << 8));
247
    } else {
248
        do_int(env, trapno);
249
    }
250
}
251

    
252
#define CHECK_IF_IN_TRAP() \
253
      if ((ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) && \
254
          (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_TFpendig)) \
255
                newflags |= TF_MASK
256

    
257
#define VM86_FAULT_RETURN \
258
        if ((ts->vm86plus.vm86plus.flags & TARGET_force_return_for_pic) && \
259
            (ts->v86flags & (IF_MASK | VIF_MASK))) \
260
            return_to_32bit(env, TARGET_VM86_PICRETURN); \
261
        return
262

    
263
void handle_vm86_fault(CPUX86State *env)
264
{
265
    TaskState *ts = env->opaque;
266
    uint32_t csp, ssp;
267
    unsigned int ip, sp, newflags, newip, newcs, opcode, intno;
268
    int data32, pref_done;
269

    
270
    csp = env->segs[R_CS].selector << 4;
271
    ip = env->eip & 0xffff;
272

    
273
    ssp = env->segs[R_SS].selector << 4;
274
    sp = env->regs[R_ESP] & 0xffff;
275

    
276
    LOG_VM86("VM86 exception %04x:%08x\n",
277
             env->segs[R_CS].selector, env->eip);
278

    
279
    data32 = 0;
280
    pref_done = 0;
281
    do {
282
        opcode = vm_getb(csp, ip);
283
        ADD16(ip, 1);
284
        switch (opcode) {
285
        case 0x66:      /* 32-bit data */     data32=1; break;
286
        case 0x67:      /* 32-bit address */  break;
287
        case 0x2e:      /* CS */              break;
288
        case 0x3e:      /* DS */              break;
289
        case 0x26:      /* ES */              break;
290
        case 0x36:      /* SS */              break;
291
        case 0x65:      /* GS */              break;
292
        case 0x64:      /* FS */              break;
293
        case 0xf2:      /* repnz */              break;
294
        case 0xf3:      /* rep */             break;
295
        default: pref_done = 1;
296
        }
297
    } while (!pref_done);
298

    
299
    /* VM86 mode */
300
    switch(opcode) {
301
    case 0x9c: /* pushf */
302
        if (data32) {
303
            vm_putl(ssp, sp - 4, get_vflags(env));
304
            ADD16(env->regs[R_ESP], -4);
305
        } else {
306
            vm_putw(ssp, sp - 2, get_vflags(env));
307
            ADD16(env->regs[R_ESP], -2);
308
        }
309
        env->eip = ip;
310
        VM86_FAULT_RETURN;
311

    
312
    case 0x9d: /* popf */
313
        if (data32) {
314
            newflags = vm_getl(ssp, sp);
315
            ADD16(env->regs[R_ESP], 4);
316
        } else {
317
            newflags = vm_getw(ssp, sp);
318
            ADD16(env->regs[R_ESP], 2);
319
        }
320
        env->eip = ip;
321
        CHECK_IF_IN_TRAP();
322
        if (data32) {
323
            if (set_vflags_long(newflags, env))
324
                return;
325
        } else {
326
            if (set_vflags_short(newflags, env))
327
                return;
328
        }
329
        VM86_FAULT_RETURN;
330

    
331
    case 0xcd: /* int */
332
        intno = vm_getb(csp, ip);
333
        ADD16(ip, 1);
334
        env->eip = ip;
335
        if (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) {
336
            if ( (ts->vm86plus.vm86plus.vm86dbg_intxxtab[intno >> 3] >>
337
                  (intno &7)) & 1) {
338
                return_to_32bit(env, TARGET_VM86_INTx + (intno << 8));
339
                return;
340
            }
341
        }
342
        do_int(env, intno);
343
        break;
344

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

    
369
    case 0xfa: /* cli */
370
        env->eip = ip;
371
        clear_IF(env);
372
        VM86_FAULT_RETURN;
373

    
374
    case 0xfb: /* sti */
375
        env->eip = ip;
376
        if (set_IF(env))
377
            return;
378
        VM86_FAULT_RETURN;
379

    
380
    default:
381
        /* real VM86 GPF exception */
382
        return_to_32bit(env, TARGET_VM86_UNKNOWN);
383
        break;
384
    }
385
}
386

    
387
int do_vm86(CPUX86State *env, long subfunction, abi_ulong vm86_addr)
388
{
389
    TaskState *ts = env->opaque;
390
    struct target_vm86plus_struct * target_v86;
391
    int ret;
392

    
393
    switch (subfunction) {
394
    case TARGET_VM86_REQUEST_IRQ:
395
    case TARGET_VM86_FREE_IRQ:
396
    case TARGET_VM86_GET_IRQ_BITS:
397
    case TARGET_VM86_GET_AND_RESET_IRQ:
398
        gemu_log("qemu: unsupported vm86 subfunction (%ld)\n", subfunction);
399
        ret = -TARGET_EINVAL;
400
        goto out;
401
    case TARGET_VM86_PLUS_INSTALL_CHECK:
402
        /* NOTE: on old vm86 stuff this will return the error
403
           from verify_area(), because the subfunction is
404
           interpreted as (invalid) address to vm86_struct.
405
           So the installation check works.
406
            */
407
        ret = 0;
408
        goto out;
409
    }
410

    
411
    /* save current CPU regs */
412
    ts->vm86_saved_regs.eax = 0; /* default vm86 syscall return code */
413
    ts->vm86_saved_regs.ebx = env->regs[R_EBX];
414
    ts->vm86_saved_regs.ecx = env->regs[R_ECX];
415
    ts->vm86_saved_regs.edx = env->regs[R_EDX];
416
    ts->vm86_saved_regs.esi = env->regs[R_ESI];
417
    ts->vm86_saved_regs.edi = env->regs[R_EDI];
418
    ts->vm86_saved_regs.ebp = env->regs[R_EBP];
419
    ts->vm86_saved_regs.esp = env->regs[R_ESP];
420
    ts->vm86_saved_regs.eflags = env->eflags;
421
    ts->vm86_saved_regs.eip  = env->eip;
422
    ts->vm86_saved_regs.cs = env->segs[R_CS].selector;
423
    ts->vm86_saved_regs.ss = env->segs[R_SS].selector;
424
    ts->vm86_saved_regs.ds = env->segs[R_DS].selector;
425
    ts->vm86_saved_regs.es = env->segs[R_ES].selector;
426
    ts->vm86_saved_regs.fs = env->segs[R_FS].selector;
427
    ts->vm86_saved_regs.gs = env->segs[R_GS].selector;
428

    
429
    ts->target_v86 = vm86_addr;
430
    if (!lock_user_struct(VERIFY_READ, target_v86, vm86_addr, 1))
431
        return -TARGET_EFAULT;
432
    /* build vm86 CPU state */
433
    ts->v86flags = tswap32(target_v86->regs.eflags);
434
    env->eflags = (env->eflags & ~SAFE_MASK) |
435
        (tswap32(target_v86->regs.eflags) & SAFE_MASK) | VM_MASK;
436

    
437
    ts->vm86plus.cpu_type = tswapl(target_v86->cpu_type);
438
    switch (ts->vm86plus.cpu_type) {
439
    case TARGET_CPU_286:
440
        ts->v86mask = 0;
441
        break;
442
    case TARGET_CPU_386:
443
        ts->v86mask = NT_MASK | IOPL_MASK;
444
        break;
445
    case TARGET_CPU_486:
446
        ts->v86mask = AC_MASK | NT_MASK | IOPL_MASK;
447
        break;
448
    default:
449
        ts->v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
450
        break;
451
    }
452

    
453
    env->regs[R_EBX] = tswap32(target_v86->regs.ebx);
454
    env->regs[R_ECX] = tswap32(target_v86->regs.ecx);
455
    env->regs[R_EDX] = tswap32(target_v86->regs.edx);
456
    env->regs[R_ESI] = tswap32(target_v86->regs.esi);
457
    env->regs[R_EDI] = tswap32(target_v86->regs.edi);
458
    env->regs[R_EBP] = tswap32(target_v86->regs.ebp);
459
    env->regs[R_ESP] = tswap32(target_v86->regs.esp);
460
    env->eip = tswap32(target_v86->regs.eip);
461
    cpu_x86_load_seg(env, R_CS, tswap16(target_v86->regs.cs));
462
    cpu_x86_load_seg(env, R_SS, tswap16(target_v86->regs.ss));
463
    cpu_x86_load_seg(env, R_DS, tswap16(target_v86->regs.ds));
464
    cpu_x86_load_seg(env, R_ES, tswap16(target_v86->regs.es));
465
    cpu_x86_load_seg(env, R_FS, tswap16(target_v86->regs.fs));
466
    cpu_x86_load_seg(env, R_GS, tswap16(target_v86->regs.gs));
467
    ret = tswap32(target_v86->regs.eax); /* eax will be restored at
468
                                            the end of the syscall */
469
    memcpy(&ts->vm86plus.int_revectored,
470
           &target_v86->int_revectored, 32);
471
    memcpy(&ts->vm86plus.int21_revectored,
472
           &target_v86->int21_revectored, 32);
473
    ts->vm86plus.vm86plus.flags = tswapl(target_v86->vm86plus.flags);
474
    memcpy(&ts->vm86plus.vm86plus.vm86dbg_intxxtab,
475
           target_v86->vm86plus.vm86dbg_intxxtab, 32);
476
    unlock_user_struct(target_v86, vm86_addr, 0);
477

    
478
    LOG_VM86("do_vm86: cs:ip=%04x:%04x\n",
479
             env->segs[R_CS].selector, env->eip);
480
    /* now the virtual CPU is ready for vm86 execution ! */
481
 out:
482
    return ret;
483
}