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bt: avoid unintended sign extension
[qemu.git] / linux-user / vm86.c
blob22a4eb9625443b81a43a71979e4b854d23db3e95
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(CPUX86State *env, uint32_t segptr,
49 unsigned int reg16, unsigned int val)
50 {
51 cpu_stw_data(env, segptr + (reg16 & 0xffff), val);
52 }
53
54 static inline void vm_putl(CPUX86State *env, uint32_t segptr,
55 unsigned int reg16, unsigned int val)
56 {
57 cpu_stl_data(env, segptr + (reg16 & 0xffff), val);
58 }
59
60 static inline unsigned int vm_getb(CPUX86State *env,
61 uint32_t segptr, unsigned int reg16)
62 {
63 return cpu_ldub_data(env, segptr + (reg16 & 0xffff));
64 }
65
66 static inline unsigned int vm_getw(CPUX86State *env,
67 uint32_t segptr, unsigned int reg16)
68 {
69 return cpu_lduw_data(env, segptr + (reg16 & 0xffff));
70 }
71
72 static inline unsigned int vm_getl(CPUX86State *env,
73 uint32_t segptr, unsigned int reg16)
74 {
75 return cpu_ldl_data(env, segptr + (reg16 & 0xffff));
76 }
77
78 void save_v86_state(CPUX86State *env)
79 {
80 CPUState *cs = CPU(x86_env_get_cpu(env));
81 TaskState *ts = cs->opaque;
82 struct target_vm86plus_struct * target_v86;
83
84 if (!lock_user_struct(VERIFY_WRITE, target_v86, ts->target_v86, 0))
85 /* FIXME - should return an error */
86 return;
87 /* put the VM86 registers in the userspace register structure */
88 target_v86->regs.eax = tswap32(env->regs[R_EAX]);
89 target_v86->regs.ebx = tswap32(env->regs[R_EBX]);
90 target_v86->regs.ecx = tswap32(env->regs[R_ECX]);
91 target_v86->regs.edx = tswap32(env->regs[R_EDX]);
92 target_v86->regs.esi = tswap32(env->regs[R_ESI]);
93 target_v86->regs.edi = tswap32(env->regs[R_EDI]);
94 target_v86->regs.ebp = tswap32(env->regs[R_EBP]);
95 target_v86->regs.esp = tswap32(env->regs[R_ESP]);
96 target_v86->regs.eip = tswap32(env->eip);
97 target_v86->regs.cs = tswap16(env->segs[R_CS].selector);
98 target_v86->regs.ss = tswap16(env->segs[R_SS].selector);
99 target_v86->regs.ds = tswap16(env->segs[R_DS].selector);
100 target_v86->regs.es = tswap16(env->segs[R_ES].selector);
101 target_v86->regs.fs = tswap16(env->segs[R_FS].selector);
102 target_v86->regs.gs = tswap16(env->segs[R_GS].selector);
103 set_flags(env->eflags, ts->v86flags, VIF_MASK | ts->v86mask);
104 target_v86->regs.eflags = tswap32(env->eflags);
105 unlock_user_struct(target_v86, ts->target_v86, 1);
106 LOG_VM86("save_v86_state: eflags=%08x cs:ip=%04x:%04x\n",
107 env->eflags, env->segs[R_CS].selector, env->eip);
108
109 /* restore 32 bit registers */
110 env->regs[R_EAX] = ts->vm86_saved_regs.eax;
111 env->regs[R_EBX] = ts->vm86_saved_regs.ebx;
112 env->regs[R_ECX] = ts->vm86_saved_regs.ecx;
113 env->regs[R_EDX] = ts->vm86_saved_regs.edx;
114 env->regs[R_ESI] = ts->vm86_saved_regs.esi;
115 env->regs[R_EDI] = ts->vm86_saved_regs.edi;
116 env->regs[R_EBP] = ts->vm86_saved_regs.ebp;
117 env->regs[R_ESP] = ts->vm86_saved_regs.esp;
118 env->eflags = ts->vm86_saved_regs.eflags;
119 env->eip = ts->vm86_saved_regs.eip;
120
121 cpu_x86_load_seg(env, R_CS, ts->vm86_saved_regs.cs);
122 cpu_x86_load_seg(env, R_SS, ts->vm86_saved_regs.ss);
123 cpu_x86_load_seg(env, R_DS, ts->vm86_saved_regs.ds);
124 cpu_x86_load_seg(env, R_ES, ts->vm86_saved_regs.es);
125 cpu_x86_load_seg(env, R_FS, ts->vm86_saved_regs.fs);
126 cpu_x86_load_seg(env, R_GS, ts->vm86_saved_regs.gs);
127 }
128
129 /* return from vm86 mode to 32 bit. The vm86() syscall will return
130 'retval' */
131 static inline void return_to_32bit(CPUX86State *env, int retval)
132 {
133 LOG_VM86("return_to_32bit: ret=0x%x\n", retval);
134 save_v86_state(env);
135 env->regs[R_EAX] = retval;
136 }
137
138 static inline int set_IF(CPUX86State *env)
139 {
140 CPUState *cs = CPU(x86_env_get_cpu(env));
141 TaskState *ts = cs->opaque;
142
143 ts->v86flags |= VIF_MASK;
144 if (ts->v86flags & VIP_MASK) {
145 return_to_32bit(env, TARGET_VM86_STI);
146 return 1;
147 }
148 return 0;
149 }
150
151 static inline void clear_IF(CPUX86State *env)
152 {
153 CPUState *cs = CPU(x86_env_get_cpu(env));
154 TaskState *ts = cs->opaque;
155
156 ts->v86flags &= ~VIF_MASK;
157 }
158
159 static inline void clear_TF(CPUX86State *env)
160 {
161 env->eflags &= ~TF_MASK;
162 }
163
164 static inline void clear_AC(CPUX86State *env)
165 {
166 env->eflags &= ~AC_MASK;
167 }
168
169 static inline int set_vflags_long(unsigned long eflags, CPUX86State *env)
170 {
171 CPUState *cs = CPU(x86_env_get_cpu(env));
172 TaskState *ts = cs->opaque;
173
174 set_flags(ts->v86flags, eflags, ts->v86mask);
175 set_flags(env->eflags, eflags, SAFE_MASK);
176 if (eflags & IF_MASK)
177 return set_IF(env);
178 else
179 clear_IF(env);
180 return 0;
181 }
182
183 static inline int set_vflags_short(unsigned short flags, CPUX86State *env)
184 {
185 CPUState *cs = CPU(x86_env_get_cpu(env));
186 TaskState *ts = cs->opaque;
187
188 set_flags(ts->v86flags, flags, ts->v86mask & 0xffff);
189 set_flags(env->eflags, flags, SAFE_MASK);
190 if (flags & IF_MASK)
191 return set_IF(env);
192 else
193 clear_IF(env);
194 return 0;
195 }
196
197 static inline unsigned int get_vflags(CPUX86State *env)
198 {
199 CPUState *cs = CPU(x86_env_get_cpu(env));
200 TaskState *ts = cs->opaque;
201 unsigned int flags;
202
203 flags = env->eflags & RETURN_MASK;
204 if (ts->v86flags & VIF_MASK)
205 flags |= IF_MASK;
206 flags |= IOPL_MASK;
207 return flags | (ts->v86flags & ts->v86mask);
208 }
209
210 #define ADD16(reg, val) reg = (reg & ~0xffff) | ((reg + (val)) & 0xffff)
211
212 /* handle VM86 interrupt (NOTE: the CPU core currently does not
213 support TSS interrupt revectoring, so this code is always executed) */
214 static void do_int(CPUX86State *env, int intno)
215 {
216 CPUState *cs = CPU(x86_env_get_cpu(env));
217 TaskState *ts = cs->opaque;
218 uint32_t int_addr, segoffs, ssp;
219 unsigned int sp;
220
221 if (env->segs[R_CS].selector == TARGET_BIOSSEG)
222 goto cannot_handle;
223 if (is_revectored(intno, &ts->vm86plus.int_revectored))
224 goto cannot_handle;
225 if (intno == 0x21 && is_revectored((env->regs[R_EAX] >> 8) & 0xff,
226 &ts->vm86plus.int21_revectored))
227 goto cannot_handle;
228 int_addr = (intno << 2);
229 segoffs = cpu_ldl_data(env, int_addr);
230 if ((segoffs >> 16) == TARGET_BIOSSEG)
231 goto cannot_handle;
232 LOG_VM86("VM86: emulating int 0x%x. CS:IP=%04x:%04x\n",
233 intno, segoffs >> 16, segoffs & 0xffff);
234 /* save old state */
235 ssp = env->segs[R_SS].selector << 4;
236 sp = env->regs[R_ESP] & 0xffff;
237 vm_putw(env, ssp, sp - 2, get_vflags(env));
238 vm_putw(env, ssp, sp - 4, env->segs[R_CS].selector);
239 vm_putw(env, ssp, sp - 6, env->eip);
240 ADD16(env->regs[R_ESP], -6);
241 /* goto interrupt handler */
242 env->eip = segoffs & 0xffff;
243 cpu_x86_load_seg(env, R_CS, segoffs >> 16);
244 clear_TF(env);
245 clear_IF(env);
246 clear_AC(env);
247 return;
248 cannot_handle:
249 LOG_VM86("VM86: return to 32 bits int 0x%x\n", intno);
250 return_to_32bit(env, TARGET_VM86_INTx | (intno << 8));
251 }
252
253 void handle_vm86_trap(CPUX86State *env, int trapno)
254 {
255 if (trapno == 1 || trapno == 3) {
256 return_to_32bit(env, TARGET_VM86_TRAP + (trapno << 8));
257 } else {
258 do_int(env, trapno);
259 }
260 }
261
262 #define CHECK_IF_IN_TRAP() \
263 if ((ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) && \
264 (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_TFpendig)) \
265 newflags |= TF_MASK
266
267 #define VM86_FAULT_RETURN \
268 if ((ts->vm86plus.vm86plus.flags & TARGET_force_return_for_pic) && \
269 (ts->v86flags & (IF_MASK | VIF_MASK))) \
270 return_to_32bit(env, TARGET_VM86_PICRETURN); \
271 return
272
273 void handle_vm86_fault(CPUX86State *env)
274 {
275 CPUState *cs = CPU(x86_env_get_cpu(env));
276 TaskState *ts = cs->opaque;
277 uint32_t csp, ssp;
278 unsigned int ip, sp, newflags, newip, newcs, opcode, intno;
279 int data32, pref_done;
280
281 csp = env->segs[R_CS].selector << 4;
282 ip = env->eip & 0xffff;
283
284 ssp = env->segs[R_SS].selector << 4;
285 sp = env->regs[R_ESP] & 0xffff;
286
287 LOG_VM86("VM86 exception %04x:%08x\n",
288 env->segs[R_CS].selector, env->eip);
289
290 data32 = 0;
291 pref_done = 0;
292 do {
293 opcode = vm_getb(env, csp, ip);
294 ADD16(ip, 1);
295 switch (opcode) {
296 case 0x66: /* 32-bit data */ data32=1; break;
297 case 0x67: /* 32-bit address */ break;
298 case 0x2e: /* CS */ break;
299 case 0x3e: /* DS */ break;
300 case 0x26: /* ES */ break;
301 case 0x36: /* SS */ break;
302 case 0x65: /* GS */ break;
303 case 0x64: /* FS */ break;
304 case 0xf2: /* repnz */ break;
305 case 0xf3: /* rep */ break;
306 default: pref_done = 1;
307 }
308 } while (!pref_done);
309
310 /* VM86 mode */
311 switch(opcode) {
312 case 0x9c: /* pushf */
313 if (data32) {
314 vm_putl(env, ssp, sp - 4, get_vflags(env));
315 ADD16(env->regs[R_ESP], -4);
316 } else {
317 vm_putw(env, ssp, sp - 2, get_vflags(env));
318 ADD16(env->regs[R_ESP], -2);
319 }
320 env->eip = ip;
321 VM86_FAULT_RETURN;
322
323 case 0x9d: /* popf */
324 if (data32) {
325 newflags = vm_getl(env, ssp, sp);
326 ADD16(env->regs[R_ESP], 4);
327 } else {
328 newflags = vm_getw(env, ssp, sp);
329 ADD16(env->regs[R_ESP], 2);
330 }
331 env->eip = ip;
332 CHECK_IF_IN_TRAP();
333 if (data32) {
334 if (set_vflags_long(newflags, env))
335 return;
336 } else {
337 if (set_vflags_short(newflags, env))
338 return;
339 }
340 VM86_FAULT_RETURN;
341
342 case 0xcd: /* int */
343 intno = vm_getb(env, csp, ip);
344 ADD16(ip, 1);
345 env->eip = ip;
346 if (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) {
347 if ( (ts->vm86plus.vm86plus.vm86dbg_intxxtab[intno >> 3] >>
348 (intno &7)) & 1) {
349 return_to_32bit(env, TARGET_VM86_INTx + (intno << 8));
350 return;
351 }
352 }
353 do_int(env, intno);
354 break;
355
356 case 0xcf: /* iret */
357 if (data32) {
358 newip = vm_getl(env, ssp, sp) & 0xffff;
359 newcs = vm_getl(env, ssp, sp + 4) & 0xffff;
360 newflags = vm_getl(env, ssp, sp + 8);
361 ADD16(env->regs[R_ESP], 12);
362 } else {
363 newip = vm_getw(env, ssp, sp);
364 newcs = vm_getw(env, ssp, sp + 2);
365 newflags = vm_getw(env, ssp, sp + 4);
366 ADD16(env->regs[R_ESP], 6);
367 }
368 env->eip = newip;
369 cpu_x86_load_seg(env, R_CS, newcs);
370 CHECK_IF_IN_TRAP();
371 if (data32) {
372 if (set_vflags_long(newflags, env))
373 return;
374 } else {
375 if (set_vflags_short(newflags, env))
376 return;
377 }
378 VM86_FAULT_RETURN;
379
380 case 0xfa: /* cli */
381 env->eip = ip;
382 clear_IF(env);
383 VM86_FAULT_RETURN;
384
385 case 0xfb: /* sti */
386 env->eip = ip;
387 if (set_IF(env))
388 return;
389 VM86_FAULT_RETURN;
390
391 default:
392 /* real VM86 GPF exception */
393 return_to_32bit(env, TARGET_VM86_UNKNOWN);
394 break;
395 }
396 }
397
398 int do_vm86(CPUX86State *env, long subfunction, abi_ulong vm86_addr)
399 {
400 CPUState *cs = CPU(x86_env_get_cpu(env));
401 TaskState *ts = cs->opaque;
402 struct target_vm86plus_struct * target_v86;
403 int ret;
404
405 switch (subfunction) {
406 case TARGET_VM86_REQUEST_IRQ:
407 case TARGET_VM86_FREE_IRQ:
408 case TARGET_VM86_GET_IRQ_BITS:
409 case TARGET_VM86_GET_AND_RESET_IRQ:
410 gemu_log("qemu: unsupported vm86 subfunction (%ld)\n", subfunction);
411 ret = -TARGET_EINVAL;
412 goto out;
413 case TARGET_VM86_PLUS_INSTALL_CHECK:
414 /* NOTE: on old vm86 stuff this will return the error
415 from verify_area(), because the subfunction is
416 interpreted as (invalid) address to vm86_struct.
417 So the installation check works.
418 */
419 ret = 0;
420 goto out;
421 }
422
423 /* save current CPU regs */
424 ts->vm86_saved_regs.eax = 0; /* default vm86 syscall return code */
425 ts->vm86_saved_regs.ebx = env->regs[R_EBX];
426 ts->vm86_saved_regs.ecx = env->regs[R_ECX];
427 ts->vm86_saved_regs.edx = env->regs[R_EDX];
428 ts->vm86_saved_regs.esi = env->regs[R_ESI];
429 ts->vm86_saved_regs.edi = env->regs[R_EDI];
430 ts->vm86_saved_regs.ebp = env->regs[R_EBP];
431 ts->vm86_saved_regs.esp = env->regs[R_ESP];
432 ts->vm86_saved_regs.eflags = env->eflags;
433 ts->vm86_saved_regs.eip = env->eip;
434 ts->vm86_saved_regs.cs = env->segs[R_CS].selector;
435 ts->vm86_saved_regs.ss = env->segs[R_SS].selector;
436 ts->vm86_saved_regs.ds = env->segs[R_DS].selector;
437 ts->vm86_saved_regs.es = env->segs[R_ES].selector;
438 ts->vm86_saved_regs.fs = env->segs[R_FS].selector;
439 ts->vm86_saved_regs.gs = env->segs[R_GS].selector;
440
441 ts->target_v86 = vm86_addr;
442 if (!lock_user_struct(VERIFY_READ, target_v86, vm86_addr, 1))
443 return -TARGET_EFAULT;
444 /* build vm86 CPU state */
445 ts->v86flags = tswap32(target_v86->regs.eflags);
446 env->eflags = (env->eflags & ~SAFE_MASK) |
447 (tswap32(target_v86->regs.eflags) & SAFE_MASK) | VM_MASK;
448
449 ts->vm86plus.cpu_type = tswapal(target_v86->cpu_type);
450 switch (ts->vm86plus.cpu_type) {
451 case TARGET_CPU_286:
452 ts->v86mask = 0;
453 break;
454 case TARGET_CPU_386:
455 ts->v86mask = NT_MASK | IOPL_MASK;
456 break;
457 case TARGET_CPU_486:
458 ts->v86mask = AC_MASK | NT_MASK | IOPL_MASK;
459 break;
460 default:
461 ts->v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
462 break;
463 }
464
465 env->regs[R_EBX] = tswap32(target_v86->regs.ebx);
466 env->regs[R_ECX] = tswap32(target_v86->regs.ecx);
467 env->regs[R_EDX] = tswap32(target_v86->regs.edx);
468 env->regs[R_ESI] = tswap32(target_v86->regs.esi);
469 env->regs[R_EDI] = tswap32(target_v86->regs.edi);
470 env->regs[R_EBP] = tswap32(target_v86->regs.ebp);
471 env->regs[R_ESP] = tswap32(target_v86->regs.esp);
472 env->eip = tswap32(target_v86->regs.eip);
473 cpu_x86_load_seg(env, R_CS, tswap16(target_v86->regs.cs));
474 cpu_x86_load_seg(env, R_SS, tswap16(target_v86->regs.ss));
475 cpu_x86_load_seg(env, R_DS, tswap16(target_v86->regs.ds));
476 cpu_x86_load_seg(env, R_ES, tswap16(target_v86->regs.es));
477 cpu_x86_load_seg(env, R_FS, tswap16(target_v86->regs.fs));
478 cpu_x86_load_seg(env, R_GS, tswap16(target_v86->regs.gs));
479 ret = tswap32(target_v86->regs.eax); /* eax will be restored at
480 the end of the syscall */
481 memcpy(&ts->vm86plus.int_revectored,
482 &target_v86->int_revectored, 32);
483 memcpy(&ts->vm86plus.int21_revectored,
484 &target_v86->int21_revectored, 32);
485 ts->vm86plus.vm86plus.flags = tswapal(target_v86->vm86plus.flags);
486 memcpy(&ts->vm86plus.vm86plus.vm86dbg_intxxtab,
487 target_v86->vm86plus.vm86dbg_intxxtab, 32);
488 unlock_user_struct(target_v86, vm86_addr, 0);
489
490 LOG_VM86("do_vm86: cs:ip=%04x:%04x\n",
491 env->segs[R_CS].selector, env->eip);
492 /* now the virtual CPU is ready for vm86 execution ! */
493 out:
494 return ret;
495 }
QEmu