1 /*
2 * linux/kernel/vm86.c
3 *
4 * Copyright (C) 1994 Linus Torvalds
5 *
6 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
7 * stack - Manfred Spraul <manfreds@colorfullife.com>
8 *
9 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle
10 * them correctly. Now the emulation will be in a
11 * consistent state after stackfaults - Kasper Dupont
12 * <kasperd@daimi.au.dk>
13 *
14 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
15 * <kasperd@daimi.au.dk>
16 *
17 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
18 * caused by Kasper Dupont's changes - Stas Sergeev
19 *
20 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
21 * Kasper Dupont <kasperd@daimi.au.dk>
22 *
23 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
24 * Kasper Dupont <kasperd@daimi.au.dk>
25 *
26 * 9 apr 2002 - Changed stack access macros to jump to a label
27 * instead of returning to userspace. This simplifies
28 * do_int, and is needed by handle_vm6_fault. Kasper
29 * Dupont <kasperd@daimi.au.dk>
30 *
31 */
32
33 #include <linux/errno.h>
34 #include <linux/sched.h>
35 #include <linux/kernel.h>
36 #include <linux/signal.h>
37 #include <linux/string.h>
38 #include <linux/ptrace.h>
39 #include <linux/mm.h>
40 #include <linux/smp.h>
41 #include <linux/smp_lock.h>
42
43 #include <asm/uaccess.h>
44 #include <asm/pgalloc.h>
45 #include <asm/io.h>
46 #include <asm/irq.h>
47
48 /*
49 * Known problems:
50 *
51 * Interrupt handling is not guaranteed:
52 * - a real x86 will disable all interrupts for one instruction
53 * after a "mov ss,xx" to make stack handling atomic even without
54 * the 'lss' instruction. We can't guarantee this in v86 mode,
55 * as the next instruction might result in a page fault or similar.
56 * - a real x86 will have interrupts disabled for one instruction
57 * past the 'sti' that enables them. We don't bother with all the
58 * details yet.
59 *
60 * Let's hope these problems do not actually matter for anything.
61 */
62
63
64 #define KVM86 ((struct kernel_vm86_struct *)regs)
65 #define VMPI KVM86->vm86plus
66
67
68 /*
69 * 8- and 16-bit register defines..
70 */
71 #define AL(regs) (((unsigned char *)&((regs)->eax))[0])
72 #define AH(regs) (((unsigned char *)&((regs)->eax))[1])
73 #define IP(regs) (*(unsigned short *)&((regs)->eip))
74 #define SP(regs) (*(unsigned short *)&((regs)->esp))
75
76 /*
77 * virtual flags (16 and 32-bit versions)
78 */
79 #define VFLAGS (*(unsigned short *)&(current->thread.v86flags))
80 #define VEFLAGS (current->thread.v86flags)
81
82 #define set_flags(X,new,mask) \
83 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
84
85 #define SAFE_MASK (0xDD5)
86 #define RETURN_MASK (0xDFF)
87
88 #define VM86_REGS_PART2 orig_eax
89 #define VM86_REGS_SIZE1 \
90 ( (unsigned)( & (((struct kernel_vm86_regs *)0)->VM86_REGS_PART2) ) )
91 #define VM86_REGS_SIZE2 (sizeof(struct kernel_vm86_regs) - VM86_REGS_SIZE1)
92
93 struct pt_regs * FASTCALL(save_v86_state(struct kernel_vm86_regs * regs));
save_v86_state(struct kernel_vm86_regs * regs)94 struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs)
95 {
96 struct tss_struct *tss;
97 struct pt_regs *ret;
98 unsigned long tmp;
99
100 if (!current->thread.vm86_info) {
101 printk("no vm86_info: BAD\n");
102 do_exit(SIGSEGV);
103 }
104 set_flags(regs->eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);
105 tmp = copy_to_user(¤t->thread.vm86_info->regs,regs, VM86_REGS_SIZE1);
106 tmp += copy_to_user(¤t->thread.vm86_info->regs.VM86_REGS_PART2,
107 ®s->VM86_REGS_PART2, VM86_REGS_SIZE2);
108 tmp += put_user(current->thread.screen_bitmap,¤t->thread.vm86_info->screen_bitmap);
109 if (tmp) {
110 printk("vm86: could not access userspace vm86_info\n");
111 do_exit(SIGSEGV);
112 }
113 tss = init_tss + smp_processor_id();
114 tss->esp0 = current->thread.esp0 = current->thread.saved_esp0;
115 current->thread.saved_esp0 = 0;
116 ret = KVM86->regs32;
117 return ret;
118 }
119
mark_screen_rdonly(struct task_struct * tsk)120 static void mark_screen_rdonly(struct task_struct * tsk)
121 {
122 pgd_t *pgd;
123 pmd_t *pmd;
124 pte_t *pte;
125 int i;
126
127 spin_lock(&tsk->mm->page_table_lock);
128 pgd = pgd_offset(tsk->mm, 0xA0000);
129 if (pgd_none(*pgd))
130 goto out;
131 if (pgd_bad(*pgd)) {
132 pgd_ERROR(*pgd);
133 pgd_clear(pgd);
134 goto out;
135 }
136 pmd = pmd_offset(pgd, 0xA0000);
137 if (pmd_none(*pmd))
138 goto out;
139 if (pmd_bad(*pmd)) {
140 pmd_ERROR(*pmd);
141 pmd_clear(pmd);
142 goto out;
143 }
144 pte = pte_offset(pmd, 0xA0000);
145 for (i = 0; i < 32; i++) {
146 if (pte_present(*pte))
147 set_pte(pte, pte_wrprotect(*pte));
148 pte++;
149 }
150 out:
151 spin_unlock(&tsk->mm->page_table_lock);
152 flush_tlb();
153 }
154
155
156
157 static int do_vm86_irq_handling(int subfunction, int irqnumber);
158 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
159
sys_vm86old(struct vm86_struct * v86)160 asmlinkage int sys_vm86old(struct vm86_struct * v86)
161 {
162 struct kernel_vm86_struct info; /* declare this _on top_,
163 * this avoids wasting of stack space.
164 * This remains on the stack until we
165 * return to 32 bit user space.
166 */
167 struct task_struct *tsk;
168 int tmp, ret = -EPERM;
169
170 tsk = current;
171 if (tsk->thread.saved_esp0)
172 goto out;
173 tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
174 tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
175 (long)&info.vm86plus - (long)&info.regs.VM86_REGS_PART2);
176 ret = -EFAULT;
177 if (tmp)
178 goto out;
179 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
180 info.regs32 = (struct pt_regs *) &v86;
181 tsk->thread.vm86_info = v86;
182 do_sys_vm86(&info, tsk);
183 ret = 0; /* we never return here */
184 out:
185 return ret;
186 }
187
188
sys_vm86(unsigned long subfunction,struct vm86plus_struct * v86)189 asmlinkage int sys_vm86(unsigned long subfunction, struct vm86plus_struct * v86)
190 {
191 struct kernel_vm86_struct info; /* declare this _on top_,
192 * this avoids wasting of stack space.
193 * This remains on the stack until we
194 * return to 32 bit user space.
195 */
196 struct task_struct *tsk;
197 int tmp, ret;
198
199 tsk = current;
200 switch (subfunction) {
201 case VM86_REQUEST_IRQ:
202 case VM86_FREE_IRQ:
203 case VM86_GET_IRQ_BITS:
204 case VM86_GET_AND_RESET_IRQ:
205 ret = do_vm86_irq_handling(subfunction,(int)v86);
206 goto out;
207 case VM86_PLUS_INSTALL_CHECK:
208 /* NOTE: on old vm86 stuff this will return the error
209 from verify_area(), because the subfunction is
210 interpreted as (invalid) address to vm86_struct.
211 So the installation check works.
212 */
213 ret = 0;
214 goto out;
215 }
216
217 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
218 ret = -EPERM;
219 if (tsk->thread.saved_esp0)
220 goto out;
221 tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
222 tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
223 (long)&info.regs32 - (long)&info.regs.VM86_REGS_PART2);
224 ret = -EFAULT;
225 if (tmp)
226 goto out;
227 info.regs32 = (struct pt_regs *) &subfunction;
228 info.vm86plus.is_vm86pus = 1;
229 tsk->thread.vm86_info = (struct vm86_struct *)v86;
230 do_sys_vm86(&info, tsk);
231 ret = 0; /* we never return here */
232 out:
233 return ret;
234 }
235
236
do_sys_vm86(struct kernel_vm86_struct * info,struct task_struct * tsk)237 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
238 {
239 struct tss_struct *tss;
240 /*
241 * make sure the vm86() system call doesn't try to do anything silly
242 */
243 info->regs.__null_ds = 0;
244 info->regs.__null_es = 0;
245
246 /* we are clearing fs,gs later just before "jmp ret_from_sys_call",
247 * because starting with Linux 2.1.x they aren't no longer saved/restored
248 */
249
250 /*
251 * The eflags register is also special: we cannot trust that the user
252 * has set it up safely, so this makes sure interrupt etc flags are
253 * inherited from protected mode.
254 */
255 VEFLAGS = info->regs.eflags;
256 info->regs.eflags &= SAFE_MASK;
257 info->regs.eflags |= info->regs32->eflags & ~SAFE_MASK;
258 info->regs.eflags |= VM_MASK;
259
260 switch (info->cpu_type) {
261 case CPU_286:
262 tsk->thread.v86mask = 0;
263 break;
264 case CPU_386:
265 tsk->thread.v86mask = NT_MASK | IOPL_MASK;
266 break;
267 case CPU_486:
268 tsk->thread.v86mask = AC_MASK | NT_MASK | IOPL_MASK;
269 break;
270 default:
271 tsk->thread.v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
272 break;
273 }
274
275 /*
276 * Save old state, set default return value (%eax) to 0
277 */
278 info->regs32->eax = 0;
279 tsk->thread.saved_esp0 = tsk->thread.esp0;
280 tss = init_tss + smp_processor_id();
281 tss->esp0 = tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0;
282
283 tsk->thread.screen_bitmap = info->screen_bitmap;
284 if (info->flags & VM86_SCREEN_BITMAP)
285 mark_screen_rdonly(tsk);
286 __asm__ __volatile__(
287 "xorl %%eax,%%eax; movl %%eax,%%fs; movl %%eax,%%gs\n\t"
288 "movl %0,%%esp\n\t"
289 "jmp ret_from_sys_call"
290 : /* no outputs */
291 :"r" (&info->regs), "b" (tsk) : "ax");
292 /* we never return here */
293 }
294
return_to_32bit(struct kernel_vm86_regs * regs16,int retval)295 static inline void return_to_32bit(struct kernel_vm86_regs * regs16, int retval)
296 {
297 struct pt_regs * regs32;
298
299 regs32 = save_v86_state(regs16);
300 regs32->eax = retval;
301 __asm__ __volatile__("movl %0,%%esp\n\t"
302 "jmp ret_from_sys_call"
303 : : "r" (regs32), "b" (current));
304 }
305
set_IF(struct kernel_vm86_regs * regs)306 static inline void set_IF(struct kernel_vm86_regs * regs)
307 {
308 VEFLAGS |= VIF_MASK;
309 if (VEFLAGS & VIP_MASK)
310 return_to_32bit(regs, VM86_STI);
311 }
312
clear_IF(struct kernel_vm86_regs * regs)313 static inline void clear_IF(struct kernel_vm86_regs * regs)
314 {
315 VEFLAGS &= ~VIF_MASK;
316 }
317
clear_TF(struct kernel_vm86_regs * regs)318 static inline void clear_TF(struct kernel_vm86_regs * regs)
319 {
320 regs->eflags &= ~TF_MASK;
321 }
322
clear_AC(struct kernel_vm86_regs * regs)323 static inline void clear_AC(struct kernel_vm86_regs * regs)
324 {
325 regs->eflags &= ~AC_MASK;
326 }
327
328 /* It is correct to call set_IF(regs) from the set_vflags_*
329 * functions. However someone forgot to call clear_IF(regs)
330 * in the opposite case.
331 * After the command sequence CLI PUSHF STI POPF you should
332 * end up with interrups disabled, but you ended up with
333 * interrupts enabled.
334 * ( I was testing my own changes, but the only bug I
335 * could find was in a function I had not changed. )
336 * [KD]
337 */
338
set_vflags_long(unsigned long eflags,struct kernel_vm86_regs * regs)339 static inline void set_vflags_long(unsigned long eflags, struct kernel_vm86_regs * regs)
340 {
341 set_flags(VEFLAGS, eflags, current->thread.v86mask);
342 set_flags(regs->eflags, eflags, SAFE_MASK);
343 if (eflags & IF_MASK)
344 set_IF(regs);
345 else
346 clear_IF(regs);
347 }
348
set_vflags_short(unsigned short flags,struct kernel_vm86_regs * regs)349 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs * regs)
350 {
351 set_flags(VFLAGS, flags, current->thread.v86mask);
352 set_flags(regs->eflags, flags, SAFE_MASK);
353 if (flags & IF_MASK)
354 set_IF(regs);
355 else
356 clear_IF(regs);
357 }
358
get_vflags(struct kernel_vm86_regs * regs)359 static inline unsigned long get_vflags(struct kernel_vm86_regs * regs)
360 {
361 unsigned long flags = regs->eflags & RETURN_MASK;
362
363 if (VEFLAGS & VIF_MASK)
364 flags |= IF_MASK;
365 else
366 flags &= ~IF_MASK;
367 flags |= IOPL_MASK;
368 return flags | (VEFLAGS & current->thread.v86mask);
369 }
370
is_revectored(int nr,struct revectored_struct * bitmap)371 static inline int is_revectored(int nr, struct revectored_struct * bitmap)
372 {
373 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
374 :"=r" (nr)
375 :"m" (*bitmap),"r" (nr));
376 return nr;
377 }
378
379 #define val_byte(val, n) (((__u8 *)&val)[n])
380
381 #define pushb(base, ptr, val, err_label) \
382 do { \
383 __u8 __val = val; \
384 ptr--; \
385 if (put_user(__val, base + ptr) < 0) \
386 goto err_label; \
387 } while(0)
388
389 #define pushw(base, ptr, val, err_label) \
390 do { \
391 __u16 __val = val; \
392 ptr--; \
393 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
394 goto err_label; \
395 ptr--; \
396 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
397 goto err_label; \
398 } while(0)
399
400 #define pushl(base, ptr, val, err_label) \
401 do { \
402 __u32 __val = val; \
403 ptr--; \
404 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
405 goto err_label; \
406 ptr--; \
407 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
408 goto err_label; \
409 ptr--; \
410 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
411 goto err_label; \
412 ptr--; \
413 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
414 goto err_label; \
415 } while(0)
416
417 #define popb(base, ptr, err_label) \
418 ({ \
419 __u8 __res; \
420 if (get_user(__res, base + ptr) < 0) \
421 goto err_label; \
422 ptr++; \
423 __res; \
424 })
425
426 #define popw(base, ptr, err_label) \
427 ({ \
428 __u16 __res; \
429 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
430 goto err_label; \
431 ptr++; \
432 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
433 goto err_label; \
434 ptr++; \
435 __res; \
436 })
437
438 #define popl(base, ptr, err_label) \
439 ({ \
440 __u32 __res; \
441 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
442 goto err_label; \
443 ptr++; \
444 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
445 goto err_label; \
446 ptr++; \
447 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
448 goto err_label; \
449 ptr++; \
450 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
451 goto err_label; \
452 ptr++; \
453 __res; \
454 })
455
456 /* There are so many possible reasons for this function to return
457 * VM86_INTx, so adding another doesn't bother me. We can expect
458 * userspace programs to be able to handle it. (Getting a problem
459 * in userspace is always better than an Oops anyway.) [KD]
460 */
do_int(struct kernel_vm86_regs * regs,int i,unsigned char * ssp,unsigned short sp)461 static void do_int(struct kernel_vm86_regs *regs, int i,
462 unsigned char * ssp, unsigned short sp)
463 {
464 unsigned long *intr_ptr, segoffs;
465
466 if (regs->cs == BIOSSEG)
467 goto cannot_handle;
468 if (is_revectored(i, &KVM86->int_revectored))
469 goto cannot_handle;
470 if (i==0x21 && is_revectored(AH(regs),&KVM86->int21_revectored))
471 goto cannot_handle;
472 intr_ptr = (unsigned long *) (i << 2);
473 if (get_user(segoffs, intr_ptr))
474 goto cannot_handle;
475 if ((segoffs >> 16) == BIOSSEG)
476 goto cannot_handle;
477 pushw(ssp, sp, get_vflags(regs), cannot_handle);
478 pushw(ssp, sp, regs->cs, cannot_handle);
479 pushw(ssp, sp, IP(regs), cannot_handle);
480 regs->cs = segoffs >> 16;
481 SP(regs) -= 6;
482 IP(regs) = segoffs & 0xffff;
483 clear_TF(regs);
484 clear_IF(regs);
485 clear_AC(regs);
486 return;
487
488 cannot_handle:
489 return_to_32bit(regs, VM86_INTx + (i << 8));
490 }
491
handle_vm86_trap(struct kernel_vm86_regs * regs,long error_code,int trapno)492 int handle_vm86_trap(struct kernel_vm86_regs * regs, long error_code, int trapno)
493 {
494 if (VMPI.is_vm86pus) {
495 if ( (trapno==3) || (trapno==1) )
496 return_to_32bit(regs, VM86_TRAP + (trapno << 8));
497 do_int(regs, trapno, (unsigned char *) (regs->ss << 4), SP(regs));
498 return 0;
499 }
500 if (trapno !=1)
501 return 1; /* we let this handle by the calling routine */
502 if (current->ptrace & PT_PTRACED) {
503 unsigned long flags;
504 spin_lock_irqsave(¤t->sigmask_lock, flags);
505 sigdelset(¤t->blocked, SIGTRAP);
506 recalc_sigpending(current);
507 spin_unlock_irqrestore(¤t->sigmask_lock, flags);
508 }
509 send_sig(SIGTRAP, current, 1);
510 current->thread.trap_no = trapno;
511 current->thread.error_code = error_code;
512 return 0;
513 }
514
handle_vm86_fault(struct kernel_vm86_regs * regs,long error_code)515 void handle_vm86_fault(struct kernel_vm86_regs * regs, long error_code)
516 {
517 unsigned char *csp, *ssp, opcode;
518 unsigned short ip, sp;
519 int data32, pref_done;
520
521 #define CHECK_IF_IN_TRAP \
522 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
523 newflags |= TF_MASK
524 #define VM86_FAULT_RETURN do { \
525 if (VMPI.force_return_for_pic && (VEFLAGS & (IF_MASK | VIF_MASK))) \
526 return_to_32bit(regs, VM86_PICRETURN); \
527 return; } while (0)
528
529 csp = (unsigned char *) (regs->cs << 4);
530 ssp = (unsigned char *) (regs->ss << 4);
531 sp = SP(regs);
532 ip = IP(regs);
533
534 data32 = 0;
535 pref_done = 0;
536 do {
537 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
538 case 0x66: /* 32-bit data */ data32=1; break;
539 case 0x67: /* 32-bit address */ break;
540 case 0x2e: /* CS */ break;
541 case 0x3e: /* DS */ break;
542 case 0x26: /* ES */ break;
543 case 0x36: /* SS */ break;
544 case 0x65: /* GS */ break;
545 case 0x64: /* FS */ break;
546 case 0xf2: /* repnz */ break;
547 case 0xf3: /* rep */ break;
548 default: pref_done = 1;
549 }
550 } while (!pref_done);
551
552 switch (opcode) {
553
554 /* pushf */
555 case 0x9c:
556 if (data32) {
557 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
558 SP(regs) -= 4;
559 } else {
560 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
561 SP(regs) -= 2;
562 }
563 IP(regs) = ip;
564 VM86_FAULT_RETURN;
565
566 /* popf */
567 case 0x9d:
568 {
569 unsigned long newflags;
570 if (data32) {
571 newflags=popl(ssp, sp, simulate_sigsegv);
572 SP(regs) += 4;
573 } else {
574 newflags = popw(ssp, sp, simulate_sigsegv);
575 SP(regs) += 2;
576 }
577 IP(regs) = ip;
578 CHECK_IF_IN_TRAP;
579 if (data32) {
580 set_vflags_long(newflags, regs);
581 } else {
582 set_vflags_short(newflags, regs);
583 }
584 VM86_FAULT_RETURN;
585 }
586
587 /* int xx */
588 case 0xcd: {
589 int intno=popb(csp, ip, simulate_sigsegv);
590 IP(regs) = ip;
591 if (VMPI.vm86dbg_active) {
592 if ( (1 << (intno &7)) & VMPI.vm86dbg_intxxtab[intno >> 3] )
593 return_to_32bit(regs, VM86_INTx + (intno << 8));
594 }
595 do_int(regs, intno, ssp, sp);
596 return;
597 }
598
599 /* iret */
600 case 0xcf:
601 {
602 unsigned long newip;
603 unsigned long newcs;
604 unsigned long newflags;
605 if (data32) {
606 newip=popl(ssp, sp, simulate_sigsegv);
607 newcs=popl(ssp, sp, simulate_sigsegv);
608 newflags=popl(ssp, sp, simulate_sigsegv);
609 SP(regs) += 12;
610 } else {
611 newip = popw(ssp, sp, simulate_sigsegv);
612 newcs = popw(ssp, sp, simulate_sigsegv);
613 newflags = popw(ssp, sp, simulate_sigsegv);
614 SP(regs) += 6;
615 }
616 IP(regs) = newip;
617 regs->cs = newcs;
618 CHECK_IF_IN_TRAP;
619 if (data32) {
620 set_vflags_long(newflags, regs);
621 } else {
622 set_vflags_short(newflags, regs);
623 }
624 VM86_FAULT_RETURN;
625 }
626
627 /* cli */
628 case 0xfa:
629 IP(regs) = ip;
630 clear_IF(regs);
631 VM86_FAULT_RETURN;
632
633 /* sti */
634 /*
635 * Damn. This is incorrect: the 'sti' instruction should actually
636 * enable interrupts after the /next/ instruction. Not good.
637 *
638 * Probably needs some horsing around with the TF flag. Aiee..
639 */
640 case 0xfb:
641 IP(regs) = ip;
642 set_IF(regs);
643 VM86_FAULT_RETURN;
644
645 default:
646 return_to_32bit(regs, VM86_UNKNOWN);
647 }
648
649 return;
650
651 simulate_sigsegv:
652 /* FIXME: After a long discussion with Stas we finally
653 * agreed, that this is wrong. Here we should
654 * really send a SIGSEGV to the user program.
655 * But how do we create the correct context? We
656 * are inside a general protection fault handler
657 * and has just returned from a page fault handler.
658 * The correct context for the signal handler
659 * should be a mixture of the two, but how do we
660 * get the information? [KD]
661 */
662 return_to_32bit(regs, VM86_UNKNOWN);
663 }
664
665 /* ---------------- vm86 special IRQ passing stuff ----------------- */
666
667 #define VM86_IRQNAME "vm86irq"
668
669 static struct vm86_irqs {
670 struct task_struct *tsk;
671 int sig;
672 } vm86_irqs[16];
673 static int irqbits;
674
675 #define ALLOWED_SIGS ( 1 /* 0 = don't send a signal */ \
676 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
677 | (1 << SIGUNUSED) )
678
irq_handler(int intno,void * dev_id,struct pt_regs * regs)679 static void irq_handler(int intno, void *dev_id, struct pt_regs * regs) {
680 int irq_bit;
681 unsigned long flags;
682
683 save_flags(flags);
684 cli();
685 irq_bit = 1 << intno;
686 if ((irqbits & irq_bit) || ! vm86_irqs[intno].tsk)
687 goto out;
688 irqbits |= irq_bit;
689 if (vm86_irqs[intno].sig)
690 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
691 /* else user will poll for IRQs */
692 out:
693 restore_flags(flags);
694 }
695
free_vm86_irq(int irqnumber)696 static inline void free_vm86_irq(int irqnumber)
697 {
698 free_irq(irqnumber,0);
699 vm86_irqs[irqnumber].tsk = 0;
700 irqbits &= ~(1 << irqnumber);
701 }
702
task_valid(struct task_struct * tsk)703 static inline int task_valid(struct task_struct *tsk)
704 {
705 struct task_struct *p;
706 int ret = 0;
707
708 read_lock(&tasklist_lock);
709 for_each_task(p) {
710 if ((p == tsk) && (p->sig)) {
711 ret = 1;
712 break;
713 }
714 }
715 read_unlock(&tasklist_lock);
716 return ret;
717 }
718
release_x86_irqs(struct task_struct * task)719 void release_x86_irqs(struct task_struct *task)
720 {
721 int i;
722 for (i=3; i<16; i++)
723 if (vm86_irqs[i].tsk == task)
724 free_vm86_irq(i);
725 }
726
handle_irq_zombies(void)727 static inline void handle_irq_zombies(void)
728 {
729 int i;
730 for (i=3; i<16; i++) {
731 if (vm86_irqs[i].tsk) {
732 if (task_valid(vm86_irqs[i].tsk)) continue;
733 free_vm86_irq(i);
734 }
735 }
736 }
737
get_and_reset_irq(int irqnumber)738 static inline int get_and_reset_irq(int irqnumber)
739 {
740 int bit;
741 unsigned long flags;
742
743 if ( (irqnumber<3) || (irqnumber>15) ) return 0;
744 if (vm86_irqs[irqnumber].tsk != current) return 0;
745 save_flags(flags);
746 cli();
747 bit = irqbits & (1 << irqnumber);
748 irqbits &= ~bit;
749 restore_flags(flags);
750 return bit;
751 }
752
753
do_vm86_irq_handling(int subfunction,int irqnumber)754 static int do_vm86_irq_handling(int subfunction, int irqnumber)
755 {
756 int ret;
757 switch (subfunction) {
758 case VM86_GET_AND_RESET_IRQ: {
759 return get_and_reset_irq(irqnumber);
760 }
761 case VM86_GET_IRQ_BITS: {
762 return irqbits;
763 }
764 case VM86_REQUEST_IRQ: {
765 int sig = irqnumber >> 8;
766 int irq = irqnumber & 255;
767 handle_irq_zombies();
768 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
769 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
770 if ( (irq<3) || (irq>15) ) return -EPERM;
771 if (vm86_irqs[irq].tsk) return -EPERM;
772 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, 0);
773 if (ret) return ret;
774 vm86_irqs[irq].sig = sig;
775 vm86_irqs[irq].tsk = current;
776 return irq;
777 }
778 case VM86_FREE_IRQ: {
779 handle_irq_zombies();
780 if ( (irqnumber<3) || (irqnumber>15) ) return -EPERM;
781 if (!vm86_irqs[irqnumber].tsk) return 0;
782 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
783 free_vm86_irq(irqnumber);
784 return 0;
785 }
786 }
787 return -EINVAL;
788 }
789
790