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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, see <http://www.gnu.org/licenses/>.
18
 */
19
#include <stdlib.h>
20
#include <stdio.h>
21
#include <stdarg.h>
22
#include <string.h>
23
#include <errno.h>
24
#include <unistd.h>
25

    
26
#include "qemu.h"
27

    
28
//#define DEBUG_VM86
29

    
30
#ifdef DEBUG_VM86
31
#  define LOG_VM86(...) qemu_log(__VA_ARGS__);
32
#else
33
#  define LOG_VM86(...) do { } while (0)
34
#endif
35

    
36

    
37
#define set_flags(X,new,mask) \
38
((X) = ((X) & ~(mask)) | ((new) & (mask)))
39

    
40
#define SAFE_MASK        (0xDD5)
41
#define RETURN_MASK        (0xDFF)
42

    
43
static inline int is_revectored(int nr, struct target_revectored_struct *bitmap)
44
{
45
    return (((uint8_t *)bitmap)[nr >> 3] >> (nr & 7)) & 1;
46
}
47

    
48
static inline void vm_putw(uint32_t segptr, unsigned int reg16, unsigned int val)
49
{
50
    stw(segptr + (reg16 & 0xffff), val);
51
}
52

    
53
static inline void vm_putl(uint32_t segptr, unsigned int reg16, unsigned int val)
54
{
55
    stl(segptr + (reg16 & 0xffff), val);
56
}
57

    
58
static inline unsigned int vm_getb(uint32_t segptr, unsigned int reg16)
59
{
60
    return ldub(segptr + (reg16 & 0xffff));
61
}
62

    
63
static inline unsigned int vm_getw(uint32_t segptr, unsigned int reg16)
64
{
65
    return lduw(segptr + (reg16 & 0xffff));
66
}
67

    
68
static inline unsigned int vm_getl(uint32_t segptr, unsigned int reg16)
69
{
70
    return ldl(segptr + (reg16 & 0xffff));
71
}
72

    
73
void save_v86_state(CPUX86State *env)
74
{
75
    TaskState *ts = env->opaque;
76
    struct target_vm86plus_struct * target_v86;
77

    
78
    if (!lock_user_struct(VERIFY_WRITE, target_v86, ts->target_v86, 0))
79
        /* FIXME - should return an error */
80
        return;
81
    /* put the VM86 registers in the userspace register structure */
82
    target_v86->regs.eax = tswap32(env->regs[R_EAX]);
83
    target_v86->regs.ebx = tswap32(env->regs[R_EBX]);
84
    target_v86->regs.ecx = tswap32(env->regs[R_ECX]);
85
    target_v86->regs.edx = tswap32(env->regs[R_EDX]);
86
    target_v86->regs.esi = tswap32(env->regs[R_ESI]);
87
    target_v86->regs.edi = tswap32(env->regs[R_EDI]);
88
    target_v86->regs.ebp = tswap32(env->regs[R_EBP]);
89
    target_v86->regs.esp = tswap32(env->regs[R_ESP]);
90
    target_v86->regs.eip = tswap32(env->eip);
91
    target_v86->regs.cs = tswap16(env->segs[R_CS].selector);
92
    target_v86->regs.ss = tswap16(env->segs[R_SS].selector);
93
    target_v86->regs.ds = tswap16(env->segs[R_DS].selector);
94
    target_v86->regs.es = tswap16(env->segs[R_ES].selector);
95
    target_v86->regs.fs = tswap16(env->segs[R_FS].selector);
96
    target_v86->regs.gs = tswap16(env->segs[R_GS].selector);
97
    set_flags(env->eflags, ts->v86flags, VIF_MASK | ts->v86mask);
98
    target_v86->regs.eflags = tswap32(env->eflags);
99
    unlock_user_struct(target_v86, ts->target_v86, 1);
100
    LOG_VM86("save_v86_state: eflags=%08x cs:ip=%04x:%04x\n",
101
             env->eflags, env->segs[R_CS].selector, env->eip);
102

    
103
    /* restore 32 bit registers */
104
    env->regs[R_EAX] = ts->vm86_saved_regs.eax;
105
    env->regs[R_EBX] = ts->vm86_saved_regs.ebx;
106
    env->regs[R_ECX] = ts->vm86_saved_regs.ecx;
107
    env->regs[R_EDX] = ts->vm86_saved_regs.edx;
108
    env->regs[R_ESI] = ts->vm86_saved_regs.esi;
109
    env->regs[R_EDI] = ts->vm86_saved_regs.edi;
110
    env->regs[R_EBP] = ts->vm86_saved_regs.ebp;
111
    env->regs[R_ESP] = ts->vm86_saved_regs.esp;
112
    env->eflags = ts->vm86_saved_regs.eflags;
113
    env->eip = ts->vm86_saved_regs.eip;
114

    
115
    cpu_x86_load_seg(env, R_CS, ts->vm86_saved_regs.cs);
116
    cpu_x86_load_seg(env, R_SS, ts->vm86_saved_regs.ss);
117
    cpu_x86_load_seg(env, R_DS, ts->vm86_saved_regs.ds);
118
    cpu_x86_load_seg(env, R_ES, ts->vm86_saved_regs.es);
119
    cpu_x86_load_seg(env, R_FS, ts->vm86_saved_regs.fs);
120
    cpu_x86_load_seg(env, R_GS, ts->vm86_saved_regs.gs);
121
}
122

    
123
/* return from vm86 mode to 32 bit. The vm86() syscall will return
124
   'retval' */
125
static inline void return_to_32bit(CPUX86State *env, int retval)
126
{
127
    LOG_VM86("return_to_32bit: ret=0x%x\n", retval);
128
    save_v86_state(env);
129
    env->regs[R_EAX] = retval;
130
}
131

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

    
136
    ts->v86flags |= VIF_MASK;
137
    if (ts->v86flags & VIP_MASK) {
138
        return_to_32bit(env, TARGET_VM86_STI);
139
        return 1;
140
    }
141
    return 0;
142
}
143

    
144
static inline void clear_IF(CPUX86State *env)
145
{
146
    TaskState *ts = env->opaque;
147

    
148
    ts->v86flags &= ~VIF_MASK;
149
}
150

    
151
static inline void clear_TF(CPUX86State *env)
152
{
153
    env->eflags &= ~TF_MASK;
154
}
155

    
156
static inline void clear_AC(CPUX86State *env)
157
{
158
    env->eflags &= ~AC_MASK;
159
}
160

    
161
static inline int set_vflags_long(unsigned long eflags, CPUX86State *env)
162
{
163
    TaskState *ts = env->opaque;
164

    
165
    set_flags(ts->v86flags, eflags, ts->v86mask);
166
    set_flags(env->eflags, eflags, SAFE_MASK);
167
    if (eflags & IF_MASK)
168
        return set_IF(env);
169
    else
170
        clear_IF(env);
171
    return 0;
172
}
173

    
174
static inline int set_vflags_short(unsigned short flags, CPUX86State *env)
175
{
176
    TaskState *ts = env->opaque;
177

    
178
    set_flags(ts->v86flags, flags, ts->v86mask & 0xffff);
179
    set_flags(env->eflags, flags, SAFE_MASK);
180
    if (flags & IF_MASK)
181
        return set_IF(env);
182
    else
183
        clear_IF(env);
184
    return 0;
185
}
186

    
187
static inline unsigned int get_vflags(CPUX86State *env)
188
{
189
    TaskState *ts = env->opaque;
190
    unsigned int flags;
191

    
192
    flags = env->eflags & RETURN_MASK;
193
    if (ts->v86flags & VIF_MASK)
194
        flags |= IF_MASK;
195
    flags |= IOPL_MASK;
196
    return flags | (ts->v86flags & ts->v86mask);
197
}
198

    
199
#define ADD16(reg, val) reg = (reg & ~0xffff) | ((reg + (val)) & 0xffff)
200

    
201
/* handle VM86 interrupt (NOTE: the CPU core currently does not
202
   support TSS interrupt revectoring, so this code is always executed) */
203
static void do_int(CPUX86State *env, int intno)
204
{
205
    TaskState *ts = env->opaque;
206
    uint32_t int_addr, segoffs, ssp;
207
    unsigned int sp;
208

    
209
    if (env->segs[R_CS].selector == TARGET_BIOSSEG)
210
        goto cannot_handle;
211
    if (is_revectored(intno, &ts->vm86plus.int_revectored))
212
        goto cannot_handle;
213
    if (intno == 0x21 && is_revectored((env->regs[R_EAX] >> 8) & 0xff,
214
                                       &ts->vm86plus.int21_revectored))
215
        goto cannot_handle;
216
    int_addr = (intno << 2);
217
    segoffs = ldl(int_addr);
218
    if ((segoffs >> 16) == TARGET_BIOSSEG)
219
        goto cannot_handle;
220
    LOG_VM86("VM86: emulating int 0x%x. CS:IP=%04x:%04x\n",
221
             intno, segoffs >> 16, segoffs & 0xffff);
222
    /* save old state */
223
    ssp = env->segs[R_SS].selector << 4;
224
    sp = env->regs[R_ESP] & 0xffff;
225
    vm_putw(ssp, sp - 2, get_vflags(env));
226
    vm_putw(ssp, sp - 4, env->segs[R_CS].selector);
227
    vm_putw(ssp, sp - 6, env->eip);
228
    ADD16(env->regs[R_ESP], -6);
229
    /* goto interrupt handler */
230
    env->eip = segoffs & 0xffff;
231
    cpu_x86_load_seg(env, R_CS, segoffs >> 16);
232
    clear_TF(env);
233
    clear_IF(env);
234
    clear_AC(env);
235
    return;
236
 cannot_handle:
237
    LOG_VM86("VM86: return to 32 bits int 0x%x\n", intno);
238
    return_to_32bit(env, TARGET_VM86_INTx | (intno << 8));
239
}
240

    
241
void handle_vm86_trap(CPUX86State *env, int trapno)
242
{
243
    if (trapno == 1 || trapno == 3) {
244
        return_to_32bit(env, TARGET_VM86_TRAP + (trapno << 8));
245
    } else {
246
        do_int(env, trapno);
247
    }
248
}
249

    
250
#define CHECK_IF_IN_TRAP() \
251
      if ((ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) && \
252
          (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_TFpendig)) \
253
                newflags |= TF_MASK
254

    
255
#define VM86_FAULT_RETURN \
256
        if ((ts->vm86plus.vm86plus.flags & TARGET_force_return_for_pic) && \
257
            (ts->v86flags & (IF_MASK | VIF_MASK))) \
258
            return_to_32bit(env, TARGET_VM86_PICRETURN); \
259
        return
260

    
261
void handle_vm86_fault(CPUX86State *env)
262
{
263
    TaskState *ts = env->opaque;
264
    uint32_t csp, ssp;
265
    unsigned int ip, sp, newflags, newip, newcs, opcode, intno;
266
    int data32, pref_done;
267

    
268
    csp = env->segs[R_CS].selector << 4;
269
    ip = env->eip & 0xffff;
270

    
271
    ssp = env->segs[R_SS].selector << 4;
272
    sp = env->regs[R_ESP] & 0xffff;
273

    
274
    LOG_VM86("VM86 exception %04x:%08x\n",
275
             env->segs[R_CS].selector, env->eip);
276

    
277
    data32 = 0;
278
    pref_done = 0;
279
    do {
280
        opcode = vm_getb(csp, ip);
281
        ADD16(ip, 1);
282
        switch (opcode) {
283
        case 0x66:      /* 32-bit data */     data32=1; break;
284
        case 0x67:      /* 32-bit address */  break;
285
        case 0x2e:      /* CS */              break;
286
        case 0x3e:      /* DS */              break;
287
        case 0x26:      /* ES */              break;
288
        case 0x36:      /* SS */              break;
289
        case 0x65:      /* GS */              break;
290
        case 0x64:      /* FS */              break;
291
        case 0xf2:      /* repnz */              break;
292
        case 0xf3:      /* rep */             break;
293
        default: pref_done = 1;
294
        }
295
    } while (!pref_done);
296

    
297
    /* VM86 mode */
298
    switch(opcode) {
299
    case 0x9c: /* pushf */
300
        if (data32) {
301
            vm_putl(ssp, sp - 4, get_vflags(env));
302
            ADD16(env->regs[R_ESP], -4);
303
        } else {
304
            vm_putw(ssp, sp - 2, get_vflags(env));
305
            ADD16(env->regs[R_ESP], -2);
306
        }
307
        env->eip = ip;
308
        VM86_FAULT_RETURN;
309

    
310
    case 0x9d: /* popf */
311
        if (data32) {
312
            newflags = vm_getl(ssp, sp);
313
            ADD16(env->regs[R_ESP], 4);
314
        } else {
315
            newflags = vm_getw(ssp, sp);
316
            ADD16(env->regs[R_ESP], 2);
317
        }
318
        env->eip = ip;
319
        CHECK_IF_IN_TRAP();
320
        if (data32) {
321
            if (set_vflags_long(newflags, env))
322
                return;
323
        } else {
324
            if (set_vflags_short(newflags, env))
325
                return;
326
        }
327
        VM86_FAULT_RETURN;
328

    
329
    case 0xcd: /* int */
330
        intno = vm_getb(csp, ip);
331
        ADD16(ip, 1);
332
        env->eip = ip;
333
        if (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) {
334
            if ( (ts->vm86plus.vm86plus.vm86dbg_intxxtab[intno >> 3] >>
335
                  (intno &7)) & 1) {
336
                return_to_32bit(env, TARGET_VM86_INTx + (intno << 8));
337
                return;
338
            }
339
        }
340
        do_int(env, intno);
341
        break;
342

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

    
367
    case 0xfa: /* cli */
368
        env->eip = ip;
369
        clear_IF(env);
370
        VM86_FAULT_RETURN;
371

    
372
    case 0xfb: /* sti */
373
        env->eip = ip;
374
        if (set_IF(env))
375
            return;
376
        VM86_FAULT_RETURN;
377

    
378
    default:
379
        /* real VM86 GPF exception */
380
        return_to_32bit(env, TARGET_VM86_UNKNOWN);
381
        break;
382
    }
383
}
384

    
385
int do_vm86(CPUX86State *env, long subfunction, abi_ulong vm86_addr)
386
{
387
    TaskState *ts = env->opaque;
388
    struct target_vm86plus_struct * target_v86;
389
    int ret;
390

    
391
    switch (subfunction) {
392
    case TARGET_VM86_REQUEST_IRQ:
393
    case TARGET_VM86_FREE_IRQ:
394
    case TARGET_VM86_GET_IRQ_BITS:
395
    case TARGET_VM86_GET_AND_RESET_IRQ:
396
        gemu_log("qemu: unsupported vm86 subfunction (%ld)\n", subfunction);
397
        ret = -TARGET_EINVAL;
398
        goto out;
399
    case TARGET_VM86_PLUS_INSTALL_CHECK:
400
        /* NOTE: on old vm86 stuff this will return the error
401
           from verify_area(), because the subfunction is
402
           interpreted as (invalid) address to vm86_struct.
403
           So the installation check works.
404
            */
405
        ret = 0;
406
        goto out;
407
    }
408

    
409
    /* save current CPU regs */
410
    ts->vm86_saved_regs.eax = 0; /* default vm86 syscall return code */
411
    ts->vm86_saved_regs.ebx = env->regs[R_EBX];
412
    ts->vm86_saved_regs.ecx = env->regs[R_ECX];
413
    ts->vm86_saved_regs.edx = env->regs[R_EDX];
414
    ts->vm86_saved_regs.esi = env->regs[R_ESI];
415
    ts->vm86_saved_regs.edi = env->regs[R_EDI];
416
    ts->vm86_saved_regs.ebp = env->regs[R_EBP];
417
    ts->vm86_saved_regs.esp = env->regs[R_ESP];
418
    ts->vm86_saved_regs.eflags = env->eflags;
419
    ts->vm86_saved_regs.eip  = env->eip;
420
    ts->vm86_saved_regs.cs = env->segs[R_CS].selector;
421
    ts->vm86_saved_regs.ss = env->segs[R_SS].selector;
422
    ts->vm86_saved_regs.ds = env->segs[R_DS].selector;
423
    ts->vm86_saved_regs.es = env->segs[R_ES].selector;
424
    ts->vm86_saved_regs.fs = env->segs[R_FS].selector;
425
    ts->vm86_saved_regs.gs = env->segs[R_GS].selector;
426

    
427
    ts->target_v86 = vm86_addr;
428
    if (!lock_user_struct(VERIFY_READ, target_v86, vm86_addr, 1))
429
        return -TARGET_EFAULT;
430
    /* build vm86 CPU state */
431
    ts->v86flags = tswap32(target_v86->regs.eflags);
432
    env->eflags = (env->eflags & ~SAFE_MASK) |
433
        (tswap32(target_v86->regs.eflags) & SAFE_MASK) | VM_MASK;
434

    
435
    ts->vm86plus.cpu_type = tswapl(target_v86->cpu_type);
436
    switch (ts->vm86plus.cpu_type) {
437
    case TARGET_CPU_286:
438
        ts->v86mask = 0;
439
        break;
440
    case TARGET_CPU_386:
441
        ts->v86mask = NT_MASK | IOPL_MASK;
442
        break;
443
    case TARGET_CPU_486:
444
        ts->v86mask = AC_MASK | NT_MASK | IOPL_MASK;
445
        break;
446
    default:
447
        ts->v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
448
        break;
449
    }
450

    
451
    env->regs[R_EBX] = tswap32(target_v86->regs.ebx);
452
    env->regs[R_ECX] = tswap32(target_v86->regs.ecx);
453
    env->regs[R_EDX] = tswap32(target_v86->regs.edx);
454
    env->regs[R_ESI] = tswap32(target_v86->regs.esi);
455
    env->regs[R_EDI] = tswap32(target_v86->regs.edi);
456
    env->regs[R_EBP] = tswap32(target_v86->regs.ebp);
457
    env->regs[R_ESP] = tswap32(target_v86->regs.esp);
458
    env->eip = tswap32(target_v86->regs.eip);
459
    cpu_x86_load_seg(env, R_CS, tswap16(target_v86->regs.cs));
460
    cpu_x86_load_seg(env, R_SS, tswap16(target_v86->regs.ss));
461
    cpu_x86_load_seg(env, R_DS, tswap16(target_v86->regs.ds));
462
    cpu_x86_load_seg(env, R_ES, tswap16(target_v86->regs.es));
463
    cpu_x86_load_seg(env, R_FS, tswap16(target_v86->regs.fs));
464
    cpu_x86_load_seg(env, R_GS, tswap16(target_v86->regs.gs));
465
    ret = tswap32(target_v86->regs.eax); /* eax will be restored at
466
                                            the end of the syscall */
467
    memcpy(&ts->vm86plus.int_revectored,
468
           &target_v86->int_revectored, 32);
469
    memcpy(&ts->vm86plus.int21_revectored,
470
           &target_v86->int21_revectored, 32);
471
    ts->vm86plus.vm86plus.flags = tswapl(target_v86->vm86plus.flags);
472
    memcpy(&ts->vm86plus.vm86plus.vm86dbg_intxxtab,
473
           target_v86->vm86plus.vm86dbg_intxxtab, 32);
474
    unlock_user_struct(target_v86, vm86_addr, 0);
475

    
476
    LOG_VM86("do_vm86: cs:ip=%04x:%04x\n",
477
             env->segs[R_CS].selector, env->eip);
478
    /* now the virtual CPU is ready for vm86 execution ! */
479
 out:
480
    return ret;
481
}