]>
git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - arch/x86/kernel/vm86_32.c
2 * Copyright (C) 1994 Linus Torvalds
4 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
5 * stack - Manfred Spraul <manfred@colorfullife.com>
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>
12 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
13 * <kasperd@daimi.au.dk>
15 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
16 * caused by Kasper Dupont's changes - Stas Sergeev
18 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
19 * Kasper Dupont <kasperd@daimi.au.dk>
21 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
22 * Kasper Dupont <kasperd@daimi.au.dk>
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>
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>
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>
45 #include <asm/uaccess.h>
47 #include <asm/tlbflush.h>
49 #include <asm/syscalls.h>
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
63 * Let's hope these problems do not actually matter for anything.
67 #define KVM86 ((struct kernel_vm86_struct *)regs)
68 #define VMPI KVM86->vm86plus
72 * 8- and 16-bit register defines..
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))
80 * virtual flags (16 and 32-bit versions)
82 #define VFLAGS (*(unsigned short *)&(current->thread.v86flags))
83 #define VEFLAGS (current->thread.v86flags)
85 #define set_flags(X, new, mask) \
86 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
88 #define SAFE_MASK (0xDD5)
89 #define RETURN_MASK (0xDFF)
91 /* convert kernel_vm86_regs to vm86_regs */
92 static int copy_vm86_regs_to_user(struct vm86_regs __user
*user
,
93 const struct kernel_vm86_regs
*regs
)
98 * kernel_vm86_regs is missing gs, so copy everything up to
99 * (but not including) orig_eax, and then rest including orig_eax.
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
));
109 /* convert vm86_regs to kernel_vm86_regs */
110 static int copy_vm86_regs_from_user(struct kernel_vm86_regs
*regs
,
111 const struct vm86_regs __user
*user
,
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
) +
126 struct pt_regs
*save_v86_state(struct kernel_vm86_regs
*regs
)
128 struct tss_struct
*tss
;
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.
139 if (!current
->thread
.vm86_info
) {
140 printk("no vm86_info: BAD\n");
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
);
147 printk("vm86: could not access userspace vm86_info\n");
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;
160 ret
->fs
= current
->thread
.saved_fs
;
161 loadsegment(gs
, current
->thread
.saved_gs
);
166 static void mark_screen_rdonly(struct mm_struct
*mm
)
175 pgd
= pgd_offset(mm
, 0xA0000);
176 if (pgd_none_or_clear_bad(pgd
))
178 pud
= pud_offset(pgd
, 0xA0000);
179 if (pud_none_or_clear_bad(pud
))
181 pmd
= pmd_offset(pud
, 0xA0000);
182 if (pmd_none_or_clear_bad(pmd
))
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
));
190 pte_unmap_unlock(pte
, ptl
);
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
);
200 asmlinkage
int sys_vm86old(struct pt_regs regs
)
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.
208 struct task_struct
*tsk
;
209 int tmp
, ret
= -EPERM
;
212 if (tsk
->thread
.saved_sp0
)
214 tmp
= copy_vm86_regs_from_user(&info
.regs
, &v86
->regs
,
215 offsetof(struct kernel_vm86_struct
, vm86plus
) -
220 memset(&info
.vm86plus
, 0, (int)&info
.regs32
- (int)&info
.vm86plus
);
222 tsk
->thread
.vm86_info
= v86
;
223 do_sys_vm86(&info
, tsk
);
224 ret
= 0; /* we never return here */
230 asmlinkage
int sys_vm86(struct pt_regs regs
)
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.
237 struct task_struct
*tsk
;
239 struct vm86plus_struct __user
*v86
;
243 case VM86_REQUEST_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
);
249 case VM86_PLUS_INSTALL_CHECK
:
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.
260 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
262 if (tsk
->thread
.saved_sp0
)
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
) -
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 */
281 static void do_sys_vm86(struct kernel_vm86_struct
*info
, struct task_struct
*tsk
)
283 struct tss_struct
*tss
;
285 * make sure the vm86() system call doesn't try to do anything silly
287 info
->regs
.pt
.ds
= 0;
288 info
->regs
.pt
.es
= 0;
289 info
->regs
.pt
.fs
= 0;
291 /* we are clearing gs later just before "jmp resume_userspace",
292 * because it is not saved/restored.
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.
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
;
305 switch (info
->cpu_type
) {
307 tsk
->thread
.v86mask
= 0;
310 tsk
->thread
.v86mask
= X86_EFLAGS_NT
| X86_EFLAGS_IOPL
;
313 tsk
->thread
.v86mask
= X86_EFLAGS_AC
| X86_EFLAGS_NT
| X86_EFLAGS_IOPL
;
316 tsk
->thread
.v86mask
= X86_EFLAGS_ID
| X86_EFLAGS_AC
| X86_EFLAGS_NT
| X86_EFLAGS_IOPL
;
321 * Save old state, set default return value (%ax) to 0
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
);
328 tss
= &per_cpu(init_tss
, get_cpu());
329 tsk
->thread
.sp0
= (unsigned long) &info
->VM86_TSS_ESP0
;
331 tsk
->thread
.sysenter_cs
= 0;
332 load_sp0(tss
, &tsk
->thread
);
335 tsk
->thread
.screen_bitmap
= info
->screen_bitmap
;
336 if (info
->flags
& VM86_SCREEN_BITMAP
)
337 mark_screen_rdonly(tsk
->mm
);
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);
343 __asm__
__volatile__(
347 "jmp resume_userspace"
349 :"r" (&info
->regs
), "r" (task_thread_info(tsk
)), "r" (0));
350 /* we never return here */
353 static inline void return_to_32bit(struct kernel_vm86_regs
*regs16
, int retval
)
355 struct pt_regs
*regs32
;
357 regs32
= save_v86_state(regs16
);
359 __asm__
__volatile__("movl %0,%%esp\n\t"
361 "jmp resume_userspace"
362 : : "r" (regs32
), "r" (current_thread_info()));
365 static inline void set_IF(struct kernel_vm86_regs
*regs
)
367 VEFLAGS
|= X86_EFLAGS_VIF
;
368 if (VEFLAGS
& X86_EFLAGS_VIP
)
369 return_to_32bit(regs
, VM86_STI
);
372 static inline void clear_IF(struct kernel_vm86_regs
*regs
)
374 VEFLAGS
&= ~X86_EFLAGS_VIF
;
377 static inline void clear_TF(struct kernel_vm86_regs
*regs
)
379 regs
->pt
.flags
&= ~X86_EFLAGS_TF
;
382 static inline void clear_AC(struct kernel_vm86_regs
*regs
)
384 regs
->pt
.flags
&= ~X86_EFLAGS_AC
;
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. )
399 static inline void set_vflags_long(unsigned long flags
, struct kernel_vm86_regs
*regs
)
401 set_flags(VEFLAGS
, flags
, current
->thread
.v86mask
);
402 set_flags(regs
->pt
.flags
, flags
, SAFE_MASK
);
403 if (flags
& X86_EFLAGS_IF
)
409 static inline void set_vflags_short(unsigned short flags
, struct kernel_vm86_regs
*regs
)
411 set_flags(VFLAGS
, flags
, current
->thread
.v86mask
);
412 set_flags(regs
->pt
.flags
, flags
, SAFE_MASK
);
413 if (flags
& X86_EFLAGS_IF
)
419 static inline unsigned long get_vflags(struct kernel_vm86_regs
*regs
)
421 unsigned long flags
= regs
->pt
.flags
& RETURN_MASK
;
423 if (VEFLAGS
& X86_EFLAGS_VIF
)
424 flags
|= X86_EFLAGS_IF
;
425 flags
|= X86_EFLAGS_IOPL
;
426 return flags
| (VEFLAGS
& current
->thread
.v86mask
);
429 static inline int is_revectored(int nr
, struct revectored_struct
*bitmap
)
431 __asm__
__volatile__("btl %2,%1\n\tsbbl %0,%0"
433 :"m" (*bitmap
), "r" (nr
));
437 #define val_byte(val, n) (((__u8 *)&val)[n])
439 #define pushb(base, ptr, val, err_label) \
443 if (put_user(__val, base + ptr) < 0) \
447 #define pushw(base, ptr, val, err_label) \
451 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
454 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
458 #define pushl(base, ptr, val, err_label) \
462 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
465 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
468 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
471 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
475 #define popb(base, ptr, err_label) \
478 if (get_user(__res, base + ptr) < 0) \
484 #define popw(base, ptr, err_label) \
487 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
490 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
496 #define popl(base, ptr, err_label) \
499 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
502 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
505 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
508 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
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]
519 static void do_int(struct kernel_vm86_regs
*regs
, int i
,
520 unsigned char __user
*ssp
, unsigned short sp
)
522 unsigned long __user
*intr_ptr
;
523 unsigned long segoffs
;
525 if (regs
->pt
.cs
== BIOSSEG
)
527 if (is_revectored(i
, &KVM86
->int_revectored
))
529 if (i
== 0x21 && is_revectored(AH(regs
), &KVM86
->int21_revectored
))
531 intr_ptr
= (unsigned long __user
*) (i
<< 2);
532 if (get_user(segoffs
, intr_ptr
))
534 if ((segoffs
>> 16) == BIOSSEG
)
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;
541 IP(regs
) = segoffs
& 0xffff;
548 return_to_32bit(regs
, VM86_INTx
+ (i
<< 8));
551 int handle_vm86_trap(struct kernel_vm86_regs
*regs
, long error_code
, int trapno
)
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
));
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
);
567 void handle_vm86_fault(struct kernel_vm86_regs
*regs
, long error_code
)
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
;
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); \
585 orig_flags
= *(unsigned short *)®s
->pt
.flags
;
587 csp
= (unsigned char __user
*) (regs
->pt
.cs
<< 4);
588 ssp
= (unsigned char __user
*) (regs
->pt
.ss
<< 4);
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;
608 } while (!pref_done
);
615 pushl(ssp
, sp
, get_vflags(regs
), simulate_sigsegv
);
618 pushw(ssp
, sp
, get_vflags(regs
), simulate_sigsegv
);
627 unsigned long newflags
;
629 newflags
= popl(ssp
, sp
, simulate_sigsegv
);
632 newflags
= popw(ssp
, sp
, simulate_sigsegv
);
638 set_vflags_long(newflags
, regs
);
640 set_vflags_short(newflags
, regs
);
647 int intno
= popb(csp
, ip
, simulate_sigsegv
);
649 if (VMPI
.vm86dbg_active
) {
650 if ((1 << (intno
& 7)) & VMPI
.vm86dbg_intxxtab
[intno
>> 3])
651 return_to_32bit(regs
, VM86_INTx
+ (intno
<< 8));
653 do_int(regs
, intno
, ssp
, sp
);
662 unsigned long newflags
;
664 newip
= popl(ssp
, sp
, simulate_sigsegv
);
665 newcs
= popl(ssp
, sp
, simulate_sigsegv
);
666 newflags
= popl(ssp
, sp
, simulate_sigsegv
);
669 newip
= popw(ssp
, sp
, simulate_sigsegv
);
670 newcs
= popw(ssp
, sp
, simulate_sigsegv
);
671 newflags
= popw(ssp
, sp
, simulate_sigsegv
);
678 set_vflags_long(newflags
, regs
);
680 set_vflags_short(newflags
, regs
);
693 * Damn. This is incorrect: the 'sti' instruction should actually
694 * enable interrupts after the /next/ instruction. Not good.
696 * Probably needs some horsing around with the TF flag. Aiee..
704 return_to_32bit(regs
, VM86_UNKNOWN
);
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]
720 return_to_32bit(regs
, VM86_UNKNOWN
);
723 /* ---------------- vm86 special IRQ passing stuff ----------------- */
725 #define VM86_IRQNAME "vm86irq"
727 static struct vm86_irqs
{
728 struct task_struct
*tsk
;
732 static DEFINE_SPINLOCK(irqbits_lock
);
735 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \
736 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
739 static irqreturn_t
irq_handler(int intno
, void *dev_id
)
744 spin_lock_irqsave(&irqbits_lock
, flags
);
745 irq_bit
= 1 << intno
;
746 if ((irqbits
& irq_bit
) || !vm86_irqs
[intno
].tsk
)
749 if (vm86_irqs
[intno
].sig
)
750 send_sig(vm86_irqs
[intno
].sig
, vm86_irqs
[intno
].tsk
, 1);
752 * IRQ will be re-enabled when user asks for the irq (whether
753 * polling or as a result of the signal)
755 disable_irq_nosync(intno
);
756 spin_unlock_irqrestore(&irqbits_lock
, flags
);
760 spin_unlock_irqrestore(&irqbits_lock
, flags
);
764 static inline void free_vm86_irq(int irqnumber
)
768 free_irq(irqnumber
, NULL
);
769 vm86_irqs
[irqnumber
].tsk
= NULL
;
771 spin_lock_irqsave(&irqbits_lock
, flags
);
772 irqbits
&= ~(1 << irqnumber
);
773 spin_unlock_irqrestore(&irqbits_lock
, flags
);
776 void release_vm86_irqs(struct task_struct
*task
)
779 for (i
= FIRST_VM86_IRQ
; i
<= LAST_VM86_IRQ
; i
++)
780 if (vm86_irqs
[i
].tsk
== task
)
784 static inline int get_and_reset_irq(int irqnumber
)
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
);
796 enable_irq(irqnumber
);
800 spin_unlock_irqrestore(&irqbits_lock
, flags
);
805 static int do_vm86_irq_handling(int subfunction
, int irqnumber
)
808 switch (subfunction
) {
809 case VM86_GET_AND_RESET_IRQ
: {
810 return get_and_reset_irq(irqnumber
);
812 case VM86_GET_IRQ_BITS
: {
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
);
824 vm86_irqs
[irq
].sig
= sig
;
825 vm86_irqs
[irq
].tsk
= current
;
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
);