1 /*
2 * Copyright (C) 1994 Linus Torvalds
3 *
4 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
5 * stack - Manfred Spraul <manfred@colorfullife.com>
6 *
7 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle
8 * them correctly. Now the emulation will be in a
9 * consistent state after stackfaults - Kasper Dupont
10 * <kasperd@daimi.au.dk>
11 *
12 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
13 * <kasperd@daimi.au.dk>
14 *
15 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
16 * caused by Kasper Dupont's changes - Stas Sergeev
17 *
18 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
19 * Kasper Dupont <kasperd@daimi.au.dk>
20 *
21 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
22 * Kasper Dupont <kasperd@daimi.au.dk>
23 *
24 * 9 apr 2002 - Changed stack access macros to jump to a label
25 * instead of returning to userspace. This simplifies
26 * do_int, and is needed by handle_vm6_fault. Kasper
27 * Dupont <kasperd@daimi.au.dk>
28 *
29 */
30
31 #include <linux/capability.h>
32 #include <linux/errno.h>
33 #include <linux/interrupt.h>
34 #include <linux/sched.h>
35 #include <linux/kernel.h>
36 #include <linux/signal.h>
37 #include <linux/string.h>
38 #include <linux/mm.h>
39 #include <linux/smp.h>
40 #include <linux/highmem.h>
41 #include <linux/ptrace.h>
42 #include <linux/audit.h>
43 #include <linux/stddef.h>
44
45 #include <asm/uaccess.h>
46 #include <asm/io.h>
47 #include <asm/tlbflush.h>
48 #include <asm/irq.h>
49 #include <asm/syscalls.h>
50
51 /*
52 * Known problems:
53 *
54 * Interrupt handling is not guaranteed:
55 * - a real x86 will disable all interrupts for one instruction
56 * after a "mov ss,xx" to make stack handling atomic even without
57 * the 'lss' instruction. We can't guarantee this in v86 mode,
58 * as the next instruction might result in a page fault or similar.
59 * - a real x86 will have interrupts disabled for one instruction
60 * past the 'sti' that enables them. We don't bother with all the
61 * details yet.
62 *
63 * Let's hope these problems do not actually matter for anything.
64 */
65
66
67 #define KVM86 ((struct kernel_vm86_struct *)regs)
68 #define VMPI KVM86->vm86plus
69
70
71 /*
72 * 8- and 16-bit register defines..
73 */
74 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0])
75 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1])
76 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip))
77 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp))
78
79 /*
80 * virtual flags (16 and 32-bit versions)
81 */
82 #define VFLAGS (*(unsigned short *)&(current->thread.v86flags))
83 #define VEFLAGS (current->thread.v86flags)
84
85 #define set_flags(X, new, mask) \
86 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
87
88 #define SAFE_MASK (0xDD5)
89 #define RETURN_MASK (0xDFF)
90
91 /* convert kernel_vm86_regs to vm86_regs */
copy_vm86_regs_to_user(struct vm86_regs __user * user,const struct kernel_vm86_regs * regs)92 static int copy_vm86_regs_to_user(struct vm86_regs __user *user,
93 const struct kernel_vm86_regs *regs)
94 {
95 int ret = 0;
96
97 /*
98 * kernel_vm86_regs is missing gs, so copy everything up to
99 * (but not including) orig_eax, and then rest including orig_eax.
100 */
101 ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.orig_ax));
102 ret += copy_to_user(&user->orig_eax, ®s->pt.orig_ax,
103 sizeof(struct kernel_vm86_regs) -
104 offsetof(struct kernel_vm86_regs, pt.orig_ax));
105
106 return ret;
107 }
108
109 /* convert vm86_regs to kernel_vm86_regs */
copy_vm86_regs_from_user(struct kernel_vm86_regs * regs,const struct vm86_regs __user * user,unsigned extra)110 static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs,
111 const struct vm86_regs __user *user,
112 unsigned extra)
113 {
114 int ret = 0;
115
116 /* copy ax-fs inclusive */
117 ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.orig_ax));
118 /* copy orig_ax-__gsh+extra */
119 ret += copy_from_user(®s->pt.orig_ax, &user->orig_eax,
120 sizeof(struct kernel_vm86_regs) -
121 offsetof(struct kernel_vm86_regs, pt.orig_ax) +
122 extra);
123 return ret;
124 }
125
save_v86_state(struct kernel_vm86_regs * regs)126 struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
127 {
128 struct tss_struct *tss;
129 struct pt_regs *ret;
130 unsigned long tmp;
131
132 /*
133 * This gets called from entry.S with interrupts disabled, but
134 * from process context. Enable interrupts here, before trying
135 * to access user space.
136 */
137 local_irq_enable();
138
139 if (!current->thread.vm86_info) {
140 printk("no vm86_info: BAD\n");
141 do_exit(SIGSEGV);
142 }
143 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | current->thread.v86mask);
144 tmp = copy_vm86_regs_to_user(¤t->thread.vm86_info->regs, regs);
145 tmp += put_user(current->thread.screen_bitmap, ¤t->thread.vm86_info->screen_bitmap);
146 if (tmp) {
147 printk("vm86: could not access userspace vm86_info\n");
148 do_exit(SIGSEGV);
149 }
150
151 tss = &per_cpu(init_tss, get_cpu());
152 current->thread.sp0 = current->thread.saved_sp0;
153 current->thread.sysenter_cs = __KERNEL_CS;
154 load_sp0(tss, ¤t->thread);
155 current->thread.saved_sp0 = 0;
156 put_cpu();
157
158 ret = KVM86->regs32;
159
160 ret->fs = current->thread.saved_fs;
161 loadsegment(gs, current->thread.saved_gs);
162
163 return ret;
164 }
165
mark_screen_rdonly(struct mm_struct * mm)166 static void mark_screen_rdonly(struct mm_struct *mm)
167 {
168 pgd_t *pgd;
169 pud_t *pud;
170 pmd_t *pmd;
171 pte_t *pte;
172 spinlock_t *ptl;
173 int i;
174
175 pgd = pgd_offset(mm, 0xA0000);
176 if (pgd_none_or_clear_bad(pgd))
177 goto out;
178 pud = pud_offset(pgd, 0xA0000);
179 if (pud_none_or_clear_bad(pud))
180 goto out;
181 pmd = pmd_offset(pud, 0xA0000);
182 if (pmd_none_or_clear_bad(pmd))
183 goto out;
184 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
185 for (i = 0; i < 32; i++) {
186 if (pte_present(*pte))
187 set_pte(pte, pte_wrprotect(*pte));
188 pte++;
189 }
190 pte_unmap_unlock(pte, ptl);
191 out:
192 flush_tlb();
193 }
194
195
196
197 static int do_vm86_irq_handling(int subfunction, int irqnumber);
198 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
199
sys_vm86old(struct pt_regs regs)200 asmlinkage int sys_vm86old(struct pt_regs regs)
201 {
202 struct vm86_struct __user *v86 = (struct vm86_struct __user *)regs.bx;
203 struct kernel_vm86_struct info; /* declare this _on top_,
204 * this avoids wasting of stack space.
205 * This remains on the stack until we
206 * return to 32 bit user space.
207 */
208 struct task_struct *tsk;
209 int tmp, ret = -EPERM;
210
211 tsk = current;
212 if (tsk->thread.saved_sp0)
213 goto out;
214 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
215 offsetof(struct kernel_vm86_struct, vm86plus) -
216 sizeof(info.regs));
217 ret = -EFAULT;
218 if (tmp)
219 goto out;
220 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
221 info.regs32 = ®s;
222 tsk->thread.vm86_info = v86;
223 do_sys_vm86(&info, tsk);
224 ret = 0; /* we never return here */
225 out:
226 return ret;
227 }
228
229
sys_vm86(struct pt_regs regs)230 asmlinkage int sys_vm86(struct pt_regs regs)
231 {
232 struct kernel_vm86_struct info; /* declare this _on top_,
233 * this avoids wasting of stack space.
234 * This remains on the stack until we
235 * return to 32 bit user space.
236 */
237 struct task_struct *tsk;
238 int tmp, ret;
239 struct vm86plus_struct __user *v86;
240
241 tsk = current;
242 switch (regs.bx) {
243 case VM86_REQUEST_IRQ:
244 case VM86_FREE_IRQ:
245 case VM86_GET_IRQ_BITS:
246 case VM86_GET_AND_RESET_IRQ:
247 ret = do_vm86_irq_handling(regs.bx, (int)regs.cx);
248 goto out;
249 case VM86_PLUS_INSTALL_CHECK:
250 /*
251 * NOTE: on old vm86 stuff this will return the error
252 * from access_ok(), because the subfunction is
253 * interpreted as (invalid) address to vm86_struct.
254 * So the installation check works.
255 */
256 ret = 0;
257 goto out;
258 }
259
260 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
261 ret = -EPERM;
262 if (tsk->thread.saved_sp0)
263 goto out;
264 v86 = (struct vm86plus_struct __user *)regs.cx;
265 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
266 offsetof(struct kernel_vm86_struct, regs32) -
267 sizeof(info.regs));
268 ret = -EFAULT;
269 if (tmp)
270 goto out;
271 info.regs32 = ®s;
272 info.vm86plus.is_vm86pus = 1;
273 tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
274 do_sys_vm86(&info, tsk);
275 ret = 0; /* we never return here */
276 out:
277 return ret;
278 }
279
280
do_sys_vm86(struct kernel_vm86_struct * info,struct task_struct * tsk)281 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
282 {
283 struct tss_struct *tss;
284 /*
285 * make sure the vm86() system call doesn't try to do anything silly
286 */
287 info->regs.pt.ds = 0;
288 info->regs.pt.es = 0;
289 info->regs.pt.fs = 0;
290
291 /* we are clearing gs later just before "jmp resume_userspace",
292 * because it is not saved/restored.
293 */
294
295 /*
296 * The flags register is also special: we cannot trust that the user
297 * has set it up safely, so this makes sure interrupt etc flags are
298 * inherited from protected mode.
299 */
300 VEFLAGS = info->regs.pt.flags;
301 info->regs.pt.flags &= SAFE_MASK;
302 info->regs.pt.flags |= info->regs32->flags & ~SAFE_MASK;
303 info->regs.pt.flags |= X86_VM_MASK;
304
305 switch (info->cpu_type) {
306 case CPU_286:
307 tsk->thread.v86mask = 0;
308 break;
309 case CPU_386:
310 tsk->thread.v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
311 break;
312 case CPU_486:
313 tsk->thread.v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
314 break;
315 default:
316 tsk->thread.v86mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
317 break;
318 }
319
320 /*
321 * Save old state, set default return value (%ax) to 0
322 */
323 info->regs32->ax = 0;
324 tsk->thread.saved_sp0 = tsk->thread.sp0;
325 tsk->thread.saved_fs = info->regs32->fs;
326 savesegment(gs, tsk->thread.saved_gs);
327
328 tss = &per_cpu(init_tss, get_cpu());
329 tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0;
330 if (cpu_has_sep)
331 tsk->thread.sysenter_cs = 0;
332 load_sp0(tss, &tsk->thread);
333 put_cpu();
334
335 tsk->thread.screen_bitmap = info->screen_bitmap;
336 if (info->flags & VM86_SCREEN_BITMAP)
337 mark_screen_rdonly(tsk->mm);
338
339 /*call audit_syscall_exit since we do not exit via the normal paths */
340 if (unlikely(current->audit_context))
341 audit_syscall_exit(AUDITSC_RESULT(0), 0);
342
343 __asm__ __volatile__(
344 "movl %0,%%esp\n\t"
345 "movl %1,%%ebp\n\t"
346 "mov %2, %%gs\n\t"
347 "jmp resume_userspace"
348 : /* no outputs */
349 :"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0));
350 /* we never return here */
351 }
352
return_to_32bit(struct kernel_vm86_regs * regs16,int retval)353 static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval)
354 {
355 struct pt_regs *regs32;
356
357 regs32 = save_v86_state(regs16);
358 regs32->ax = retval;
359 __asm__ __volatile__("movl %0,%%esp\n\t"
360 "movl %1,%%ebp\n\t"
361 "jmp resume_userspace"
362 : : "r" (regs32), "r" (current_thread_info()));
363 }
364
set_IF(struct kernel_vm86_regs * regs)365 static inline void set_IF(struct kernel_vm86_regs *regs)
366 {
367 VEFLAGS |= X86_EFLAGS_VIF;
368 if (VEFLAGS & X86_EFLAGS_VIP)
369 return_to_32bit(regs, VM86_STI);
370 }
371
clear_IF(struct kernel_vm86_regs * regs)372 static inline void clear_IF(struct kernel_vm86_regs *regs)
373 {
374 VEFLAGS &= ~X86_EFLAGS_VIF;
375 }
376
clear_TF(struct kernel_vm86_regs * regs)377 static inline void clear_TF(struct kernel_vm86_regs *regs)
378 {
379 regs->pt.flags &= ~X86_EFLAGS_TF;
380 }
381
clear_AC(struct kernel_vm86_regs * regs)382 static inline void clear_AC(struct kernel_vm86_regs *regs)
383 {
384 regs->pt.flags &= ~X86_EFLAGS_AC;
385 }
386
387 /*
388 * It is correct to call set_IF(regs) from the set_vflags_*
389 * functions. However someone forgot to call clear_IF(regs)
390 * in the opposite case.
391 * After the command sequence CLI PUSHF STI POPF you should
392 * end up with interrupts disabled, but you ended up with
393 * interrupts enabled.
394 * ( I was testing my own changes, but the only bug I
395 * could find was in a function I had not changed. )
396 * [KD]
397 */
398
set_vflags_long(unsigned long flags,struct kernel_vm86_regs * regs)399 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs)
400 {
401 set_flags(VEFLAGS, flags, current->thread.v86mask);
402 set_flags(regs->pt.flags, flags, SAFE_MASK);
403 if (flags & X86_EFLAGS_IF)
404 set_IF(regs);
405 else
406 clear_IF(regs);
407 }
408
set_vflags_short(unsigned short flags,struct kernel_vm86_regs * regs)409 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs)
410 {
411 set_flags(VFLAGS, flags, current->thread.v86mask);
412 set_flags(regs->pt.flags, flags, SAFE_MASK);
413 if (flags & X86_EFLAGS_IF)
414 set_IF(regs);
415 else
416 clear_IF(regs);
417 }
418
get_vflags(struct kernel_vm86_regs * regs)419 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs)
420 {
421 unsigned long flags = regs->pt.flags & RETURN_MASK;
422
423 if (VEFLAGS & X86_EFLAGS_VIF)
424 flags |= X86_EFLAGS_IF;
425 flags |= X86_EFLAGS_IOPL;
426 return flags | (VEFLAGS & current->thread.v86mask);
427 }
428
is_revectored(int nr,struct revectored_struct * bitmap)429 static inline int is_revectored(int nr, struct revectored_struct *bitmap)
430 {
431 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
432 :"=r" (nr)
433 :"m" (*bitmap), "r" (nr));
434 return nr;
435 }
436
437 #define val_byte(val, n) (((__u8 *)&val)[n])
438
439 #define pushb(base, ptr, val, err_label) \
440 do { \
441 __u8 __val = val; \
442 ptr--; \
443 if (put_user(__val, base + ptr) < 0) \
444 goto err_label; \
445 } while (0)
446
447 #define pushw(base, ptr, val, err_label) \
448 do { \
449 __u16 __val = val; \
450 ptr--; \
451 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
452 goto err_label; \
453 ptr--; \
454 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
455 goto err_label; \
456 } while (0)
457
458 #define pushl(base, ptr, val, err_label) \
459 do { \
460 __u32 __val = val; \
461 ptr--; \
462 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
463 goto err_label; \
464 ptr--; \
465 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
466 goto err_label; \
467 ptr--; \
468 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
469 goto err_label; \
470 ptr--; \
471 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
472 goto err_label; \
473 } while (0)
474
475 #define popb(base, ptr, err_label) \
476 ({ \
477 __u8 __res; \
478 if (get_user(__res, base + ptr) < 0) \
479 goto err_label; \
480 ptr++; \
481 __res; \
482 })
483
484 #define popw(base, ptr, err_label) \
485 ({ \
486 __u16 __res; \
487 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
488 goto err_label; \
489 ptr++; \
490 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
491 goto err_label; \
492 ptr++; \
493 __res; \
494 })
495
496 #define popl(base, ptr, err_label) \
497 ({ \
498 __u32 __res; \
499 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
500 goto err_label; \
501 ptr++; \
502 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
503 goto err_label; \
504 ptr++; \
505 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
506 goto err_label; \
507 ptr++; \
508 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
509 goto err_label; \
510 ptr++; \
511 __res; \
512 })
513
514 /* There are so many possible reasons for this function to return
515 * VM86_INTx, so adding another doesn't bother me. We can expect
516 * userspace programs to be able to handle it. (Getting a problem
517 * in userspace is always better than an Oops anyway.) [KD]
518 */
do_int(struct kernel_vm86_regs * regs,int i,unsigned char __user * ssp,unsigned short sp)519 static void do_int(struct kernel_vm86_regs *regs, int i,
520 unsigned char __user *ssp, unsigned short sp)
521 {
522 unsigned long __user *intr_ptr;
523 unsigned long segoffs;
524
525 if (regs->pt.cs == BIOSSEG)
526 goto cannot_handle;
527 if (is_revectored(i, &KVM86->int_revectored))
528 goto cannot_handle;
529 if (i == 0x21 && is_revectored(AH(regs), &KVM86->int21_revectored))
530 goto cannot_handle;
531 intr_ptr = (unsigned long __user *) (i << 2);
532 if (get_user(segoffs, intr_ptr))
533 goto cannot_handle;
534 if ((segoffs >> 16) == BIOSSEG)
535 goto cannot_handle;
536 pushw(ssp, sp, get_vflags(regs), cannot_handle);
537 pushw(ssp, sp, regs->pt.cs, cannot_handle);
538 pushw(ssp, sp, IP(regs), cannot_handle);
539 regs->pt.cs = segoffs >> 16;
540 SP(regs) -= 6;
541 IP(regs) = segoffs & 0xffff;
542 clear_TF(regs);
543 clear_IF(regs);
544 clear_AC(regs);
545 return;
546
547 cannot_handle:
548 return_to_32bit(regs, VM86_INTx + (i << 8));
549 }
550
handle_vm86_trap(struct kernel_vm86_regs * regs,long error_code,int trapno)551 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno)
552 {
553 if (VMPI.is_vm86pus) {
554 if ((trapno == 3) || (trapno == 1))
555 return_to_32bit(regs, VM86_TRAP + (trapno << 8));
556 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs));
557 return 0;
558 }
559 if (trapno != 1)
560 return 1; /* we let this handle by the calling routine */
561 current->thread.trap_no = trapno;
562 current->thread.error_code = error_code;
563 force_sig(SIGTRAP, current);
564 return 0;
565 }
566
handle_vm86_fault(struct kernel_vm86_regs * regs,long error_code)567 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code)
568 {
569 unsigned char opcode;
570 unsigned char __user *csp;
571 unsigned char __user *ssp;
572 unsigned short ip, sp, orig_flags;
573 int data32, pref_done;
574
575 #define CHECK_IF_IN_TRAP \
576 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
577 newflags |= X86_EFLAGS_TF
578 #define VM86_FAULT_RETURN do { \
579 if (VMPI.force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \
580 return_to_32bit(regs, VM86_PICRETURN); \
581 if (orig_flags & X86_EFLAGS_TF) \
582 handle_vm86_trap(regs, 0, 1); \
583 return; } while (0)
584
585 orig_flags = *(unsigned short *)®s->pt.flags;
586
587 csp = (unsigned char __user *) (regs->pt.cs << 4);
588 ssp = (unsigned char __user *) (regs->pt.ss << 4);
589 sp = SP(regs);
590 ip = IP(regs);
591
592 data32 = 0;
593 pref_done = 0;
594 do {
595 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
596 case 0x66: /* 32-bit data */ data32 = 1; break;
597 case 0x67: /* 32-bit address */ break;
598 case 0x2e: /* CS */ break;
599 case 0x3e: /* DS */ break;
600 case 0x26: /* ES */ break;
601 case 0x36: /* SS */ break;
602 case 0x65: /* GS */ break;
603 case 0x64: /* FS */ break;
604 case 0xf2: /* repnz */ break;
605 case 0xf3: /* rep */ break;
606 default: pref_done = 1;
607 }
608 } while (!pref_done);
609
610 switch (opcode) {
611
612 /* pushf */
613 case 0x9c:
614 if (data32) {
615 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
616 SP(regs) -= 4;
617 } else {
618 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
619 SP(regs) -= 2;
620 }
621 IP(regs) = ip;
622 VM86_FAULT_RETURN;
623
624 /* popf */
625 case 0x9d:
626 {
627 unsigned long newflags;
628 if (data32) {
629 newflags = popl(ssp, sp, simulate_sigsegv);
630 SP(regs) += 4;
631 } else {
632 newflags = popw(ssp, sp, simulate_sigsegv);
633 SP(regs) += 2;
634 }
635 IP(regs) = ip;
636 CHECK_IF_IN_TRAP;
637 if (data32)
638 set_vflags_long(newflags, regs);
639 else
640 set_vflags_short(newflags, regs);
641
642 VM86_FAULT_RETURN;
643 }
644
645 /* int xx */
646 case 0xcd: {
647 int intno = popb(csp, ip, simulate_sigsegv);
648 IP(regs) = ip;
649 if (VMPI.vm86dbg_active) {
650 if ((1 << (intno & 7)) & VMPI.vm86dbg_intxxtab[intno >> 3])
651 return_to_32bit(regs, VM86_INTx + (intno << 8));
652 }
653 do_int(regs, intno, ssp, sp);
654 return;
655 }
656
657 /* iret */
658 case 0xcf:
659 {
660 unsigned long newip;
661 unsigned long newcs;
662 unsigned long newflags;
663 if (data32) {
664 newip = popl(ssp, sp, simulate_sigsegv);
665 newcs = popl(ssp, sp, simulate_sigsegv);
666 newflags = popl(ssp, sp, simulate_sigsegv);
667 SP(regs) += 12;
668 } else {
669 newip = popw(ssp, sp, simulate_sigsegv);
670 newcs = popw(ssp, sp, simulate_sigsegv);
671 newflags = popw(ssp, sp, simulate_sigsegv);
672 SP(regs) += 6;
673 }
674 IP(regs) = newip;
675 regs->pt.cs = newcs;
676 CHECK_IF_IN_TRAP;
677 if (data32) {
678 set_vflags_long(newflags, regs);
679 } else {
680 set_vflags_short(newflags, regs);
681 }
682 VM86_FAULT_RETURN;
683 }
684
685 /* cli */
686 case 0xfa:
687 IP(regs) = ip;
688 clear_IF(regs);
689 VM86_FAULT_RETURN;
690
691 /* sti */
692 /*
693 * Damn. This is incorrect: the 'sti' instruction should actually
694 * enable interrupts after the /next/ instruction. Not good.
695 *
696 * Probably needs some horsing around with the TF flag. Aiee..
697 */
698 case 0xfb:
699 IP(regs) = ip;
700 set_IF(regs);
701 VM86_FAULT_RETURN;
702
703 default:
704 return_to_32bit(regs, VM86_UNKNOWN);
705 }
706
707 return;
708
709 simulate_sigsegv:
710 /* FIXME: After a long discussion with Stas we finally
711 * agreed, that this is wrong. Here we should
712 * really send a SIGSEGV to the user program.
713 * But how do we create the correct context? We
714 * are inside a general protection fault handler
715 * and has just returned from a page fault handler.
716 * The correct context for the signal handler
717 * should be a mixture of the two, but how do we
718 * get the information? [KD]
719 */
720 return_to_32bit(regs, VM86_UNKNOWN);
721 }
722
723 /* ---------------- vm86 special IRQ passing stuff ----------------- */
724
725 #define VM86_IRQNAME "vm86irq"
726
727 static struct vm86_irqs {
728 struct task_struct *tsk;
729 int sig;
730 } vm86_irqs[16];
731
732 static DEFINE_SPINLOCK(irqbits_lock);
733 static int irqbits;
734
735 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \
736 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
737 | (1 << SIGUNUSED))
738
irq_handler(int intno,void * dev_id)739 static irqreturn_t irq_handler(int intno, void *dev_id)
740 {
741 int irq_bit;
742 unsigned long flags;
743
744 spin_lock_irqsave(&irqbits_lock, flags);
745 irq_bit = 1 << intno;
746 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk)
747 goto out;
748 irqbits |= irq_bit;
749 if (vm86_irqs[intno].sig)
750 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
751 /*
752 * IRQ will be re-enabled when user asks for the irq (whether
753 * polling or as a result of the signal)
754 */
755 disable_irq_nosync(intno);
756 spin_unlock_irqrestore(&irqbits_lock, flags);
757 return IRQ_HANDLED;
758
759 out:
760 spin_unlock_irqrestore(&irqbits_lock, flags);
761 return IRQ_NONE;
762 }
763
free_vm86_irq(int irqnumber)764 static inline void free_vm86_irq(int irqnumber)
765 {
766 unsigned long flags;
767
768 free_irq(irqnumber, NULL);
769 vm86_irqs[irqnumber].tsk = NULL;
770
771 spin_lock_irqsave(&irqbits_lock, flags);
772 irqbits &= ~(1 << irqnumber);
773 spin_unlock_irqrestore(&irqbits_lock, flags);
774 }
775
release_vm86_irqs(struct task_struct * task)776 void release_vm86_irqs(struct task_struct *task)
777 {
778 int i;
779 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
780 if (vm86_irqs[i].tsk == task)
781 free_vm86_irq(i);
782 }
783
get_and_reset_irq(int irqnumber)784 static inline int get_and_reset_irq(int irqnumber)
785 {
786 int bit;
787 unsigned long flags;
788 int ret = 0;
789
790 if (invalid_vm86_irq(irqnumber)) return 0;
791 if (vm86_irqs[irqnumber].tsk != current) return 0;
792 spin_lock_irqsave(&irqbits_lock, flags);
793 bit = irqbits & (1 << irqnumber);
794 irqbits &= ~bit;
795 if (bit) {
796 enable_irq(irqnumber);
797 ret = 1;
798 }
799
800 spin_unlock_irqrestore(&irqbits_lock, flags);
801 return ret;
802 }
803
804
do_vm86_irq_handling(int subfunction,int irqnumber)805 static int do_vm86_irq_handling(int subfunction, int irqnumber)
806 {
807 int ret;
808 switch (subfunction) {
809 case VM86_GET_AND_RESET_IRQ: {
810 return get_and_reset_irq(irqnumber);
811 }
812 case VM86_GET_IRQ_BITS: {
813 return irqbits;
814 }
815 case VM86_REQUEST_IRQ: {
816 int sig = irqnumber >> 8;
817 int irq = irqnumber & 255;
818 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
819 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
820 if (invalid_vm86_irq(irq)) return -EPERM;
821 if (vm86_irqs[irq].tsk) return -EPERM;
822 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL);
823 if (ret) return ret;
824 vm86_irqs[irq].sig = sig;
825 vm86_irqs[irq].tsk = current;
826 return irq;
827 }
828 case VM86_FREE_IRQ: {
829 if (invalid_vm86_irq(irqnumber)) return -EPERM;
830 if (!vm86_irqs[irqnumber].tsk) return 0;
831 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
832 free_vm86_irq(irqnumber);
833 return 0;
834 }
835 }
836 return -EINVAL;
837 }
838
839