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qga/qapi-schema: Delete useless "Returns" sections
[qemu/kevin.git] / linux-user / vm86.c
blobc2facf3fc2de320cef4bf6614ec502a05d7a739f
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 "qemu/osdep.h"
20
21 #include "qemu.h"
22 #include "user-internals.h"
23
24 //#define DEBUG_VM86
25
26 #ifdef DEBUG_VM86
27 # define LOG_VM86(...) qemu_log(__VA_ARGS__);
28 #else
29 # define LOG_VM86(...) do { } while (0)
30 #endif
31
32
33 #define set_flags(X,new,mask) \
34 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
35
36 #define SAFE_MASK (0xDD5)
37 #define RETURN_MASK (0xDFF)
38
39 static inline int is_revectored(int nr, struct target_revectored_struct *bitmap)
40 {
41 return (((uint8_t *)bitmap)[nr >> 3] >> (nr & 7)) & 1;
42 }
43
44 static inline void vm_putw(CPUX86State *env, uint32_t segptr,
45 unsigned int reg16, unsigned int val)
46 {
47 cpu_stw_data(env, segptr + (reg16 & 0xffff), val);
48 }
49
50 static inline void vm_putl(CPUX86State *env, uint32_t segptr,
51 unsigned int reg16, unsigned int val)
52 {
53 cpu_stl_data(env, segptr + (reg16 & 0xffff), val);
54 }
55
56 static inline unsigned int vm_getb(CPUX86State *env,
57 uint32_t segptr, unsigned int reg16)
58 {
59 return cpu_ldub_data(env, segptr + (reg16 & 0xffff));
60 }
61
62 static inline unsigned int vm_getw(CPUX86State *env,
63 uint32_t segptr, unsigned int reg16)
64 {
65 return cpu_lduw_data(env, segptr + (reg16 & 0xffff));
66 }
67
68 static inline unsigned int vm_getl(CPUX86State *env,
69 uint32_t segptr, unsigned int reg16)
70 {
71 return cpu_ldl_data(env, segptr + (reg16 & 0xffff));
72 }
73
74 void save_v86_state(CPUX86State *env)
75 {
76 CPUState *cs = env_cpu(env);
77 TaskState *ts = cs->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 CPUState *cs = env_cpu(env);
137 TaskState *ts = cs->opaque;
138
139 ts->v86flags |= VIF_MASK;
140 if (ts->v86flags & VIP_MASK) {
141 return_to_32bit(env, TARGET_VM86_STI);
142 return 1;
143 }
144 return 0;
145 }
146
147 static inline void clear_IF(CPUX86State *env)
148 {
149 CPUState *cs = env_cpu(env);
150 TaskState *ts = cs->opaque;
151
152 ts->v86flags &= ~VIF_MASK;
153 }
154
155 static inline void clear_TF(CPUX86State *env)
156 {
157 env->eflags &= ~TF_MASK;
158 }
159
160 static inline void clear_AC(CPUX86State *env)
161 {
162 env->eflags &= ~AC_MASK;
163 }
164
165 static inline int set_vflags_long(unsigned long eflags, CPUX86State *env)
166 {
167 CPUState *cs = env_cpu(env);
168 TaskState *ts = cs->opaque;
169
170 set_flags(ts->v86flags, eflags, ts->v86mask);
171 set_flags(env->eflags, eflags, SAFE_MASK);
172 if (eflags & IF_MASK)
173 return set_IF(env);
174 else
175 clear_IF(env);
176 return 0;
177 }
178
179 static inline int set_vflags_short(unsigned short flags, CPUX86State *env)
180 {
181 CPUState *cs = env_cpu(env);
182 TaskState *ts = cs->opaque;
183
184 set_flags(ts->v86flags, flags, ts->v86mask & 0xffff);
185 set_flags(env->eflags, flags, SAFE_MASK);
186 if (flags & IF_MASK)
187 return set_IF(env);
188 else
189 clear_IF(env);
190 return 0;
191 }
192
193 static inline unsigned int get_vflags(CPUX86State *env)
194 {
195 CPUState *cs = env_cpu(env);
196 TaskState *ts = cs->opaque;
197 unsigned int flags;
198
199 flags = env->eflags & RETURN_MASK;
200 if (ts->v86flags & VIF_MASK)
201 flags |= IF_MASK;
202 flags |= IOPL_MASK;
203 return flags | (ts->v86flags & ts->v86mask);
204 }
205
206 #define ADD16(reg, val) reg = (reg & ~0xffff) | ((reg + (val)) & 0xffff)
207
208 /* handle VM86 interrupt (NOTE: the CPU core currently does not
209 support TSS interrupt revectoring, so this code is always executed) */
210 static void do_int(CPUX86State *env, int intno)
211 {
212 CPUState *cs = env_cpu(env);
213 TaskState *ts = cs->opaque;
214 uint32_t int_addr, segoffs, ssp;
215 unsigned int sp;
216
217 if (env->segs[R_CS].selector == TARGET_BIOSSEG)
218 goto cannot_handle;
219 if (is_revectored(intno, &ts->vm86plus.int_revectored))
220 goto cannot_handle;
221 if (intno == 0x21 && is_revectored((env->regs[R_EAX] >> 8) & 0xff,
222 &ts->vm86plus.int21_revectored))
223 goto cannot_handle;
224 int_addr = (intno << 2);
225 segoffs = cpu_ldl_data(env, int_addr);
226 if ((segoffs >> 16) == TARGET_BIOSSEG)
227 goto cannot_handle;
228 LOG_VM86("VM86: emulating int 0x%x. CS:IP=%04x:%04x\n",
229 intno, segoffs >> 16, segoffs & 0xffff);
230 /* save old state */
231 ssp = env->segs[R_SS].selector << 4;
232 sp = env->regs[R_ESP] & 0xffff;
233 vm_putw(env, ssp, sp - 2, get_vflags(env));
234 vm_putw(env, ssp, sp - 4, env->segs[R_CS].selector);
235 vm_putw(env, ssp, sp - 6, env->eip);
236 ADD16(env->regs[R_ESP], -6);
237 /* goto interrupt handler */
238 env->eip = segoffs & 0xffff;
239 cpu_x86_load_seg(env, R_CS, segoffs >> 16);
240 clear_TF(env);
241 clear_IF(env);
242 clear_AC(env);
243 return;
244 cannot_handle:
245 LOG_VM86("VM86: return to 32 bits int 0x%x\n", intno);
246 return_to_32bit(env, TARGET_VM86_INTx | (intno << 8));
247 }
248
249 void handle_vm86_trap(CPUX86State *env, int trapno)
250 {
251 if (trapno == 1 || trapno == 3) {
252 return_to_32bit(env, TARGET_VM86_TRAP + (trapno << 8));
253 } else {
254 do_int(env, trapno);
255 }
256 }
257
258 #define CHECK_IF_IN_TRAP() \
259 if ((ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) && \
260 (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_TFpendig)) \
261 newflags |= TF_MASK
262
263 #define VM86_FAULT_RETURN \
264 if ((ts->vm86plus.vm86plus.flags & TARGET_force_return_for_pic) && \
265 (ts->v86flags & (IF_MASK | VIF_MASK))) \
266 return_to_32bit(env, TARGET_VM86_PICRETURN); \
267 return
268
269 void handle_vm86_fault(CPUX86State *env)
270 {
271 CPUState *cs = env_cpu(env);
272 TaskState *ts = cs->opaque;
273 uint32_t csp, ssp;
274 unsigned int ip, sp, newflags, newip, newcs, opcode, intno;
275 int data32, pref_done;
276
277 csp = env->segs[R_CS].selector << 4;
278 ip = env->eip & 0xffff;
279
280 ssp = env->segs[R_SS].selector << 4;
281 sp = env->regs[R_ESP] & 0xffff;
282
283 LOG_VM86("VM86 exception %04x:%08x\n",
284 env->segs[R_CS].selector, env->eip);
285
286 data32 = 0;
287 pref_done = 0;
288 do {
289 opcode = vm_getb(env, csp, ip);
290 ADD16(ip, 1);
291 switch (opcode) {
292 case 0x66: /* 32-bit data */ data32=1; break;
293 case 0x67: /* 32-bit address */ break;
294 case 0x2e: /* CS */ break;
295 case 0x3e: /* DS */ break;
296 case 0x26: /* ES */ break;
297 case 0x36: /* SS */ break;
298 case 0x65: /* GS */ break;
299 case 0x64: /* FS */ break;
300 case 0xf2: /* repnz */ break;
301 case 0xf3: /* rep */ break;
302 default: pref_done = 1;
303 }
304 } while (!pref_done);
305
306 /* VM86 mode */
307 switch(opcode) {
308 case 0x9c: /* pushf */
309 if (data32) {
310 vm_putl(env, ssp, sp - 4, get_vflags(env));
311 ADD16(env->regs[R_ESP], -4);
312 } else {
313 vm_putw(env, ssp, sp - 2, get_vflags(env));
314 ADD16(env->regs[R_ESP], -2);
315 }
316 env->eip = ip;
317 VM86_FAULT_RETURN;
318
319 case 0x9d: /* popf */
320 if (data32) {
321 newflags = vm_getl(env, ssp, sp);
322 ADD16(env->regs[R_ESP], 4);
323 } else {
324 newflags = vm_getw(env, ssp, sp);
325 ADD16(env->regs[R_ESP], 2);
326 }
327 env->eip = ip;
328 CHECK_IF_IN_TRAP();
329 if (data32) {
330 if (set_vflags_long(newflags, env))
331 return;
332 } else {
333 if (set_vflags_short(newflags, env))
334 return;
335 }
336 VM86_FAULT_RETURN;
337
338 case 0xcd: /* int */
339 intno = vm_getb(env, csp, ip);
340 ADD16(ip, 1);
341 env->eip = ip;
342 if (ts->vm86plus.vm86plus.flags & TARGET_vm86dbg_active) {
343 if ( (ts->vm86plus.vm86plus.vm86dbg_intxxtab[intno >> 3] >>
344 (intno &7)) & 1) {
345 return_to_32bit(env, TARGET_VM86_INTx + (intno << 8));
346 return;
347 }
348 }
349 do_int(env, intno);
350 break;
351
352 case 0xcf: /* iret */
353 if (data32) {
354 newip = vm_getl(env, ssp, sp) & 0xffff;
355 newcs = vm_getl(env, ssp, sp + 4) & 0xffff;
356 newflags = vm_getl(env, ssp, sp + 8);
357 ADD16(env->regs[R_ESP], 12);
358 } else {
359 newip = vm_getw(env, ssp, sp);
360 newcs = vm_getw(env, ssp, sp + 2);
361 newflags = vm_getw(env, ssp, sp + 4);
362 ADD16(env->regs[R_ESP], 6);
363 }
364 env->eip = newip;
365 cpu_x86_load_seg(env, R_CS, newcs);
366 CHECK_IF_IN_TRAP();
367 if (data32) {
368 if (set_vflags_long(newflags, env))
369 return;
370 } else {
371 if (set_vflags_short(newflags, env))
372 return;
373 }
374 VM86_FAULT_RETURN;
375
376 case 0xfa: /* cli */
377 env->eip = ip;
378 clear_IF(env);
379 VM86_FAULT_RETURN;
380
381 case 0xfb: /* sti */
382 env->eip = ip;
383 if (set_IF(env))
384 return;
385 VM86_FAULT_RETURN;
386
387 default:
388 /* real VM86 GPF exception */
389 return_to_32bit(env, TARGET_VM86_UNKNOWN);
390 break;
391 }
392 }
393
394 int do_vm86(CPUX86State *env, long subfunction, abi_ulong vm86_addr)
395 {
396 CPUState *cs = env_cpu(env);
397 TaskState *ts = cs->opaque;
398 struct target_vm86plus_struct * target_v86;
399 int ret;
400
401 switch (subfunction) {
402 case TARGET_VM86_REQUEST_IRQ:
403 case TARGET_VM86_FREE_IRQ:
404 case TARGET_VM86_GET_IRQ_BITS:
405 case TARGET_VM86_GET_AND_RESET_IRQ:
406 qemu_log_mask(LOG_UNIMP, "qemu: unsupported vm86 subfunction (%ld)\n",
407 subfunction);
408 ret = -TARGET_EINVAL;
409 goto out;
410 case TARGET_VM86_PLUS_INSTALL_CHECK:
411 /* NOTE: on old vm86 stuff this will return the error
412 from verify_area(), because the subfunction is
413 interpreted as (invalid) address to vm86_struct.
414 So the installation check works.
415 */
416 ret = 0;
417 goto out;
418 }
419
420 /* save current CPU regs */
421 ts->vm86_saved_regs.eax = 0; /* default vm86 syscall return code */
422 ts->vm86_saved_regs.ebx = env->regs[R_EBX];
423 ts->vm86_saved_regs.ecx = env->regs[R_ECX];
424 ts->vm86_saved_regs.edx = env->regs[R_EDX];
425 ts->vm86_saved_regs.esi = env->regs[R_ESI];
426 ts->vm86_saved_regs.edi = env->regs[R_EDI];
427 ts->vm86_saved_regs.ebp = env->regs[R_EBP];
428 ts->vm86_saved_regs.esp = env->regs[R_ESP];
429 ts->vm86_saved_regs.eflags = env->eflags;
430 ts->vm86_saved_regs.eip = env->eip;
431 ts->vm86_saved_regs.cs = env->segs[R_CS].selector;
432 ts->vm86_saved_regs.ss = env->segs[R_SS].selector;
433 ts->vm86_saved_regs.ds = env->segs[R_DS].selector;
434 ts->vm86_saved_regs.es = env->segs[R_ES].selector;
435 ts->vm86_saved_regs.fs = env->segs[R_FS].selector;
436 ts->vm86_saved_regs.gs = env->segs[R_GS].selector;
437
438 ts->target_v86 = vm86_addr;
439 if (!lock_user_struct(VERIFY_READ, target_v86, vm86_addr, 1))
440 return -TARGET_EFAULT;
441 /* build vm86 CPU state */
442 ts->v86flags = tswap32(target_v86->regs.eflags);
443 env->eflags = (env->eflags & ~SAFE_MASK) |
444 (tswap32(target_v86->regs.eflags) & SAFE_MASK) | VM_MASK;
445
446 ts->vm86plus.cpu_type = tswapal(target_v86->cpu_type);
447 switch (ts->vm86plus.cpu_type) {
448 case TARGET_CPU_286:
449 ts->v86mask = 0;
450 break;
451 case TARGET_CPU_386:
452 ts->v86mask = NT_MASK | IOPL_MASK;
453 break;
454 case TARGET_CPU_486:
455 ts->v86mask = AC_MASK | NT_MASK | IOPL_MASK;
456 break;
457 default:
458 ts->v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
459 break;
460 }
461
462 env->regs[R_EBX] = tswap32(target_v86->regs.ebx);
463 env->regs[R_ECX] = tswap32(target_v86->regs.ecx);
464 env->regs[R_EDX] = tswap32(target_v86->regs.edx);
465 env->regs[R_ESI] = tswap32(target_v86->regs.esi);
466 env->regs[R_EDI] = tswap32(target_v86->regs.edi);
467 env->regs[R_EBP] = tswap32(target_v86->regs.ebp);
468 env->regs[R_ESP] = tswap32(target_v86->regs.esp);
469 env->eip = tswap32(target_v86->regs.eip);
470 cpu_x86_load_seg(env, R_CS, tswap16(target_v86->regs.cs));
471 cpu_x86_load_seg(env, R_SS, tswap16(target_v86->regs.ss));
472 cpu_x86_load_seg(env, R_DS, tswap16(target_v86->regs.ds));
473 cpu_x86_load_seg(env, R_ES, tswap16(target_v86->regs.es));
474 cpu_x86_load_seg(env, R_FS, tswap16(target_v86->regs.fs));
475 cpu_x86_load_seg(env, R_GS, tswap16(target_v86->regs.gs));
476 ret = tswap32(target_v86->regs.eax); /* eax will be restored at
477 the end of the syscall */
478 memcpy(&ts->vm86plus.int_revectored,
479 &target_v86->int_revectored, 32);
480 memcpy(&ts->vm86plus.int21_revectored,
481 &target_v86->int21_revectored, 32);
482 ts->vm86plus.vm86plus.flags = tswapal(target_v86->vm86plus.flags);
483 memcpy(&ts->vm86plus.vm86plus.vm86dbg_intxxtab,
484 target_v86->vm86plus.vm86dbg_intxxtab, 32);
485 unlock_user_struct(target_v86, vm86_addr, 0);
486
487 LOG_VM86("do_vm86: cs:ip=%04x:%04x\n",
488 env->segs[R_CS].selector, env->eip);
489 /* now the virtual CPU is ready for vm86 execution ! */
490 out:
491 return ret;
492 }
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