1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1994 Linus Torvalds
5 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
6 * stack - Manfred Spraul <manfred@colorfullife.com>
8 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle
9 * them correctly. Now the emulation will be in a
10 * consistent state after stackfaults - Kasper Dupont
11 * <kasperd@daimi.au.dk>
13 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
14 * <kasperd@daimi.au.dk>
16 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
17 * caused by Kasper Dupont's changes - Stas Sergeev
19 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
20 * Kasper Dupont <kasperd@daimi.au.dk>
22 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
23 * Kasper Dupont <kasperd@daimi.au.dk>
25 * 9 apr 2002 - Changed stack access macros to jump to a label
26 * instead of returning to userspace. This simplifies
27 * do_int, and is needed by handle_vm6_fault. Kasper
28 * Dupont <kasperd@daimi.au.dk>
32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34 #include <linux/capability.h>
35 #include <linux/errno.h>
36 #include <linux/interrupt.h>
37 #include <linux/syscalls.h>
38 #include <linux/sched.h>
39 #include <linux/sched/task_stack.h>
40 #include <linux/kernel.h>
41 #include <linux/signal.h>
42 #include <linux/string.h>
44 #include <linux/smp.h>
45 #include <linux/highmem.h>
46 #include <linux/ptrace.h>
47 #include <linux/audit.h>
48 #include <linux/stddef.h>
49 #include <linux/slab.h>
50 #include <linux/security.h>
52 #include <linux/uaccess.h>
54 #include <asm/tlbflush.h>
56 #include <asm/traps.h>
62 * Interrupt handling is not guaranteed:
63 * - a real x86 will disable all interrupts for one instruction
64 * after a "mov ss,xx" to make stack handling atomic even without
65 * the 'lss' instruction. We can't guarantee this in v86 mode,
66 * as the next instruction might result in a page fault or similar.
67 * - a real x86 will have interrupts disabled for one instruction
68 * past the 'sti' that enables them. We don't bother with all the
71 * Let's hope these problems do not actually matter for anything.
76 * 8- and 16-bit register defines..
78 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0])
79 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1])
80 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip))
81 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp))
84 * virtual flags (16 and 32-bit versions)
86 #define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags))
87 #define VEFLAGS (current->thread.vm86->veflags)
89 #define set_flags(X, new, mask) \
90 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
92 #define SAFE_MASK (0xDD5)
93 #define RETURN_MASK (0xDFF)
95 void save_v86_state(struct kernel_vm86_regs
*regs
, int retval
)
97 struct tss_struct
*tss
;
98 struct task_struct
*tsk
= current
;
99 struct vm86plus_struct __user
*user
;
100 struct vm86
*vm86
= current
->thread
.vm86
;
104 * This gets called from entry.S with interrupts disabled, but
105 * from process context. Enable interrupts here, before trying
106 * to access user space.
110 if (!vm86
|| !vm86
->user_vm86
) {
111 pr_alert("no user_vm86: BAD\n");
114 set_flags(regs
->pt
.flags
, VEFLAGS
, X86_EFLAGS_VIF
| vm86
->veflags_mask
);
115 user
= vm86
->user_vm86
;
117 if (!access_ok(VERIFY_WRITE
, user
, vm86
->vm86plus
.is_vm86pus
?
118 sizeof(struct vm86plus_struct
) :
119 sizeof(struct vm86_struct
))) {
120 pr_alert("could not access userspace vm86 info\n");
125 put_user_ex(regs
->pt
.bx
, &user
->regs
.ebx
);
126 put_user_ex(regs
->pt
.cx
, &user
->regs
.ecx
);
127 put_user_ex(regs
->pt
.dx
, &user
->regs
.edx
);
128 put_user_ex(regs
->pt
.si
, &user
->regs
.esi
);
129 put_user_ex(regs
->pt
.di
, &user
->regs
.edi
);
130 put_user_ex(regs
->pt
.bp
, &user
->regs
.ebp
);
131 put_user_ex(regs
->pt
.ax
, &user
->regs
.eax
);
132 put_user_ex(regs
->pt
.ip
, &user
->regs
.eip
);
133 put_user_ex(regs
->pt
.cs
, &user
->regs
.cs
);
134 put_user_ex(regs
->pt
.flags
, &user
->regs
.eflags
);
135 put_user_ex(regs
->pt
.sp
, &user
->regs
.esp
);
136 put_user_ex(regs
->pt
.ss
, &user
->regs
.ss
);
137 put_user_ex(regs
->es
, &user
->regs
.es
);
138 put_user_ex(regs
->ds
, &user
->regs
.ds
);
139 put_user_ex(regs
->fs
, &user
->regs
.fs
);
140 put_user_ex(regs
->gs
, &user
->regs
.gs
);
142 put_user_ex(vm86
->screen_bitmap
, &user
->screen_bitmap
);
143 } put_user_catch(err
);
145 pr_alert("could not access userspace vm86 info\n");
149 tss
= &per_cpu(cpu_tss
, get_cpu());
150 tsk
->thread
.sp0
= vm86
->saved_sp0
;
151 tsk
->thread
.sysenter_cs
= __KERNEL_CS
;
152 load_sp0(tss
, &tsk
->thread
);
156 memcpy(®s
->pt
, &vm86
->regs32
, sizeof(struct pt_regs
));
158 lazy_load_gs(vm86
->regs32
.gs
);
160 regs
->pt
.ax
= retval
;
163 static void mark_screen_rdonly(struct mm_struct
*mm
)
165 struct vm_area_struct
*vma
;
174 down_write(&mm
->mmap_sem
);
175 pgd
= pgd_offset(mm
, 0xA0000);
176 if (pgd_none_or_clear_bad(pgd
))
178 p4d
= p4d_offset(pgd
, 0xA0000);
179 if (p4d_none_or_clear_bad(p4d
))
181 pud
= pud_offset(p4d
, 0xA0000);
182 if (pud_none_or_clear_bad(pud
))
184 pmd
= pmd_offset(pud
, 0xA0000);
186 if (pmd_trans_huge(*pmd
)) {
187 vma
= find_vma(mm
, 0xA0000);
188 split_huge_pmd(vma
, pmd
, 0xA0000);
190 if (pmd_none_or_clear_bad(pmd
))
192 pte
= pte_offset_map_lock(mm
, pmd
, 0xA0000, &ptl
);
193 for (i
= 0; i
< 32; i
++) {
194 if (pte_present(*pte
))
195 set_pte(pte
, pte_wrprotect(*pte
));
198 pte_unmap_unlock(pte
, ptl
);
200 up_write(&mm
->mmap_sem
);
201 flush_tlb_mm_range(mm
, 0xA0000, 0xA0000 + 32*PAGE_SIZE
, 0UL);
206 static int do_vm86_irq_handling(int subfunction
, int irqnumber
);
207 static long do_sys_vm86(struct vm86plus_struct __user
*user_vm86
, bool plus
);
209 SYSCALL_DEFINE1(vm86old
, struct vm86_struct __user
*, user_vm86
)
211 return do_sys_vm86((struct vm86plus_struct __user
*) user_vm86
, false);
215 SYSCALL_DEFINE2(vm86
, unsigned long, cmd
, unsigned long, arg
)
218 case VM86_REQUEST_IRQ
:
220 case VM86_GET_IRQ_BITS
:
221 case VM86_GET_AND_RESET_IRQ
:
222 return do_vm86_irq_handling(cmd
, (int)arg
);
223 case VM86_PLUS_INSTALL_CHECK
:
225 * NOTE: on old vm86 stuff this will return the error
226 * from access_ok(), because the subfunction is
227 * interpreted as (invalid) address to vm86_struct.
228 * So the installation check works.
233 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
234 return do_sys_vm86((struct vm86plus_struct __user
*) arg
, true);
238 static long do_sys_vm86(struct vm86plus_struct __user
*user_vm86
, bool plus
)
240 struct tss_struct
*tss
;
241 struct task_struct
*tsk
= current
;
242 struct vm86
*vm86
= tsk
->thread
.vm86
;
243 struct kernel_vm86_regs vm86regs
;
244 struct pt_regs
*regs
= current_pt_regs();
245 unsigned long err
= 0;
247 err
= security_mmap_addr(0);
250 * vm86 cannot virtualize the address space, so vm86 users
251 * need to manage the low 1MB themselves using mmap. Given
252 * that BIOS places important data in the first page, vm86
253 * is essentially useless if mmap_min_addr != 0. DOSEMU,
254 * for example, won't even bother trying to use vm86 if it
255 * can't map a page at virtual address 0.
257 * To reduce the available kernel attack surface, simply
258 * disallow vm86(old) for users who cannot mmap at va 0.
260 * The implementation of security_mmap_addr will allow
261 * suitably privileged users to map va 0 even if
262 * vm.mmap_min_addr is set above 0, and we want this
263 * behavior for vm86 as well, as it ensures that legacy
264 * tools like vbetool will not fail just because of
267 pr_info_once("Denied a call to vm86(old) from %s[%d] (uid: %d). Set the vm.mmap_min_addr sysctl to 0 and/or adjust LSM mmap_min_addr policy to enable vm86 if you are using a vm86-based DOS emulator.\n",
268 current
->comm
, task_pid_nr(current
),
269 from_kuid_munged(&init_user_ns
, current_uid()));
274 if (!(vm86
= kzalloc(sizeof(*vm86
), GFP_KERNEL
)))
276 tsk
->thread
.vm86
= vm86
;
281 if (!access_ok(VERIFY_READ
, user_vm86
, plus
?
282 sizeof(struct vm86_struct
) :
283 sizeof(struct vm86plus_struct
)))
286 memset(&vm86regs
, 0, sizeof(vm86regs
));
289 get_user_ex(vm86regs
.pt
.bx
, &user_vm86
->regs
.ebx
);
290 get_user_ex(vm86regs
.pt
.cx
, &user_vm86
->regs
.ecx
);
291 get_user_ex(vm86regs
.pt
.dx
, &user_vm86
->regs
.edx
);
292 get_user_ex(vm86regs
.pt
.si
, &user_vm86
->regs
.esi
);
293 get_user_ex(vm86regs
.pt
.di
, &user_vm86
->regs
.edi
);
294 get_user_ex(vm86regs
.pt
.bp
, &user_vm86
->regs
.ebp
);
295 get_user_ex(vm86regs
.pt
.ax
, &user_vm86
->regs
.eax
);
296 get_user_ex(vm86regs
.pt
.ip
, &user_vm86
->regs
.eip
);
297 get_user_ex(seg
, &user_vm86
->regs
.cs
);
298 vm86regs
.pt
.cs
= seg
;
299 get_user_ex(vm86regs
.pt
.flags
, &user_vm86
->regs
.eflags
);
300 get_user_ex(vm86regs
.pt
.sp
, &user_vm86
->regs
.esp
);
301 get_user_ex(seg
, &user_vm86
->regs
.ss
);
302 vm86regs
.pt
.ss
= seg
;
303 get_user_ex(vm86regs
.es
, &user_vm86
->regs
.es
);
304 get_user_ex(vm86regs
.ds
, &user_vm86
->regs
.ds
);
305 get_user_ex(vm86regs
.fs
, &user_vm86
->regs
.fs
);
306 get_user_ex(vm86regs
.gs
, &user_vm86
->regs
.gs
);
308 get_user_ex(vm86
->flags
, &user_vm86
->flags
);
309 get_user_ex(vm86
->screen_bitmap
, &user_vm86
->screen_bitmap
);
310 get_user_ex(vm86
->cpu_type
, &user_vm86
->cpu_type
);
311 } get_user_catch(err
);
315 if (copy_from_user(&vm86
->int_revectored
,
316 &user_vm86
->int_revectored
,
317 sizeof(struct revectored_struct
)))
319 if (copy_from_user(&vm86
->int21_revectored
,
320 &user_vm86
->int21_revectored
,
321 sizeof(struct revectored_struct
)))
324 if (copy_from_user(&vm86
->vm86plus
, &user_vm86
->vm86plus
,
325 sizeof(struct vm86plus_info_struct
)))
327 vm86
->vm86plus
.is_vm86pus
= 1;
329 memset(&vm86
->vm86plus
, 0,
330 sizeof(struct vm86plus_info_struct
));
332 memcpy(&vm86
->regs32
, regs
, sizeof(struct pt_regs
));
333 vm86
->user_vm86
= user_vm86
;
336 * The flags register is also special: we cannot trust that the user
337 * has set it up safely, so this makes sure interrupt etc flags are
338 * inherited from protected mode.
340 VEFLAGS
= vm86regs
.pt
.flags
;
341 vm86regs
.pt
.flags
&= SAFE_MASK
;
342 vm86regs
.pt
.flags
|= regs
->flags
& ~SAFE_MASK
;
343 vm86regs
.pt
.flags
|= X86_VM_MASK
;
345 vm86regs
.pt
.orig_ax
= regs
->orig_ax
;
347 switch (vm86
->cpu_type
) {
349 vm86
->veflags_mask
= 0;
352 vm86
->veflags_mask
= X86_EFLAGS_NT
| X86_EFLAGS_IOPL
;
355 vm86
->veflags_mask
= X86_EFLAGS_AC
| X86_EFLAGS_NT
| X86_EFLAGS_IOPL
;
358 vm86
->veflags_mask
= X86_EFLAGS_ID
| X86_EFLAGS_AC
| X86_EFLAGS_NT
| X86_EFLAGS_IOPL
;
365 vm86
->saved_sp0
= tsk
->thread
.sp0
;
366 lazy_save_gs(vm86
->regs32
.gs
);
368 tss
= &per_cpu(cpu_tss
, get_cpu());
369 /* make room for real-mode segments */
370 tsk
->thread
.sp0
+= 16;
372 if (static_cpu_has(X86_FEATURE_SEP
))
373 tsk
->thread
.sysenter_cs
= 0;
375 load_sp0(tss
, &tsk
->thread
);
378 if (vm86
->flags
& VM86_SCREEN_BITMAP
)
379 mark_screen_rdonly(tsk
->mm
);
381 memcpy((struct kernel_vm86_regs
*)regs
, &vm86regs
, sizeof(vm86regs
));
386 static inline void set_IF(struct kernel_vm86_regs
*regs
)
388 VEFLAGS
|= X86_EFLAGS_VIF
;
391 static inline void clear_IF(struct kernel_vm86_regs
*regs
)
393 VEFLAGS
&= ~X86_EFLAGS_VIF
;
396 static inline void clear_TF(struct kernel_vm86_regs
*regs
)
398 regs
->pt
.flags
&= ~X86_EFLAGS_TF
;
401 static inline void clear_AC(struct kernel_vm86_regs
*regs
)
403 regs
->pt
.flags
&= ~X86_EFLAGS_AC
;
407 * It is correct to call set_IF(regs) from the set_vflags_*
408 * functions. However someone forgot to call clear_IF(regs)
409 * in the opposite case.
410 * After the command sequence CLI PUSHF STI POPF you should
411 * end up with interrupts disabled, but you ended up with
412 * interrupts enabled.
413 * ( I was testing my own changes, but the only bug I
414 * could find was in a function I had not changed. )
418 static inline void set_vflags_long(unsigned long flags
, struct kernel_vm86_regs
*regs
)
420 set_flags(VEFLAGS
, flags
, current
->thread
.vm86
->veflags_mask
);
421 set_flags(regs
->pt
.flags
, flags
, SAFE_MASK
);
422 if (flags
& X86_EFLAGS_IF
)
428 static inline void set_vflags_short(unsigned short flags
, struct kernel_vm86_regs
*regs
)
430 set_flags(VFLAGS
, flags
, current
->thread
.vm86
->veflags_mask
);
431 set_flags(regs
->pt
.flags
, flags
, SAFE_MASK
);
432 if (flags
& X86_EFLAGS_IF
)
438 static inline unsigned long get_vflags(struct kernel_vm86_regs
*regs
)
440 unsigned long flags
= regs
->pt
.flags
& RETURN_MASK
;
442 if (VEFLAGS
& X86_EFLAGS_VIF
)
443 flags
|= X86_EFLAGS_IF
;
444 flags
|= X86_EFLAGS_IOPL
;
445 return flags
| (VEFLAGS
& current
->thread
.vm86
->veflags_mask
);
448 static inline int is_revectored(int nr
, struct revectored_struct
*bitmap
)
450 return test_bit(nr
, bitmap
->__map
);
453 #define val_byte(val, n) (((__u8 *)&val)[n])
455 #define pushb(base, ptr, val, err_label) \
459 if (put_user(__val, base + ptr) < 0) \
463 #define pushw(base, ptr, val, err_label) \
467 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
470 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
474 #define pushl(base, ptr, val, err_label) \
478 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
481 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
484 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
487 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
491 #define popb(base, ptr, err_label) \
494 if (get_user(__res, base + ptr) < 0) \
500 #define popw(base, ptr, err_label) \
503 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
506 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
512 #define popl(base, ptr, err_label) \
515 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
518 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
521 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
524 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
530 /* There are so many possible reasons for this function to return
531 * VM86_INTx, so adding another doesn't bother me. We can expect
532 * userspace programs to be able to handle it. (Getting a problem
533 * in userspace is always better than an Oops anyway.) [KD]
535 static void do_int(struct kernel_vm86_regs
*regs
, int i
,
536 unsigned char __user
*ssp
, unsigned short sp
)
538 unsigned long __user
*intr_ptr
;
539 unsigned long segoffs
;
540 struct vm86
*vm86
= current
->thread
.vm86
;
542 if (regs
->pt
.cs
== BIOSSEG
)
544 if (is_revectored(i
, &vm86
->int_revectored
))
546 if (i
== 0x21 && is_revectored(AH(regs
), &vm86
->int21_revectored
))
548 intr_ptr
= (unsigned long __user
*) (i
<< 2);
549 if (get_user(segoffs
, intr_ptr
))
551 if ((segoffs
>> 16) == BIOSSEG
)
553 pushw(ssp
, sp
, get_vflags(regs
), cannot_handle
);
554 pushw(ssp
, sp
, regs
->pt
.cs
, cannot_handle
);
555 pushw(ssp
, sp
, IP(regs
), cannot_handle
);
556 regs
->pt
.cs
= segoffs
>> 16;
558 IP(regs
) = segoffs
& 0xffff;
565 save_v86_state(regs
, VM86_INTx
+ (i
<< 8));
568 int handle_vm86_trap(struct kernel_vm86_regs
*regs
, long error_code
, int trapno
)
570 struct vm86
*vm86
= current
->thread
.vm86
;
572 if (vm86
->vm86plus
.is_vm86pus
) {
573 if ((trapno
== 3) || (trapno
== 1)) {
574 save_v86_state(regs
, VM86_TRAP
+ (trapno
<< 8));
577 do_int(regs
, trapno
, (unsigned char __user
*) (regs
->pt
.ss
<< 4), SP(regs
));
581 return 1; /* we let this handle by the calling routine */
582 current
->thread
.trap_nr
= trapno
;
583 current
->thread
.error_code
= error_code
;
584 force_sig(SIGTRAP
, current
);
588 void handle_vm86_fault(struct kernel_vm86_regs
*regs
, long error_code
)
590 unsigned char opcode
;
591 unsigned char __user
*csp
;
592 unsigned char __user
*ssp
;
593 unsigned short ip
, sp
, orig_flags
;
594 int data32
, pref_done
;
595 struct vm86plus_info_struct
*vmpi
= ¤t
->thread
.vm86
->vm86plus
;
597 #define CHECK_IF_IN_TRAP \
598 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \
599 newflags |= X86_EFLAGS_TF
601 orig_flags
= *(unsigned short *)®s
->pt
.flags
;
603 csp
= (unsigned char __user
*) (regs
->pt
.cs
<< 4);
604 ssp
= (unsigned char __user
*) (regs
->pt
.ss
<< 4);
611 switch (opcode
= popb(csp
, ip
, simulate_sigsegv
)) {
612 case 0x66: /* 32-bit data */ data32
= 1; break;
613 case 0x67: /* 32-bit address */ break;
614 case 0x2e: /* CS */ break;
615 case 0x3e: /* DS */ break;
616 case 0x26: /* ES */ break;
617 case 0x36: /* SS */ break;
618 case 0x65: /* GS */ break;
619 case 0x64: /* FS */ break;
620 case 0xf2: /* repnz */ break;
621 case 0xf3: /* rep */ break;
622 default: pref_done
= 1;
624 } while (!pref_done
);
631 pushl(ssp
, sp
, get_vflags(regs
), simulate_sigsegv
);
634 pushw(ssp
, sp
, get_vflags(regs
), simulate_sigsegv
);
638 goto vm86_fault_return
;
643 unsigned long newflags
;
645 newflags
= popl(ssp
, sp
, simulate_sigsegv
);
648 newflags
= popw(ssp
, sp
, simulate_sigsegv
);
654 set_vflags_long(newflags
, regs
);
656 set_vflags_short(newflags
, regs
);
663 int intno
= popb(csp
, ip
, simulate_sigsegv
);
665 if (vmpi
->vm86dbg_active
) {
666 if ((1 << (intno
& 7)) & vmpi
->vm86dbg_intxxtab
[intno
>> 3]) {
667 save_v86_state(regs
, VM86_INTx
+ (intno
<< 8));
671 do_int(regs
, intno
, ssp
, sp
);
680 unsigned long newflags
;
682 newip
= popl(ssp
, sp
, simulate_sigsegv
);
683 newcs
= popl(ssp
, sp
, simulate_sigsegv
);
684 newflags
= popl(ssp
, sp
, simulate_sigsegv
);
687 newip
= popw(ssp
, sp
, simulate_sigsegv
);
688 newcs
= popw(ssp
, sp
, simulate_sigsegv
);
689 newflags
= popw(ssp
, sp
, simulate_sigsegv
);
696 set_vflags_long(newflags
, regs
);
698 set_vflags_short(newflags
, regs
);
707 goto vm86_fault_return
;
711 * Damn. This is incorrect: the 'sti' instruction should actually
712 * enable interrupts after the /next/ instruction. Not good.
714 * Probably needs some horsing around with the TF flag. Aiee..
722 save_v86_state(regs
, VM86_UNKNOWN
);
728 if (VEFLAGS
& X86_EFLAGS_VIP
) {
729 save_v86_state(regs
, VM86_STI
);
734 if (vmpi
->force_return_for_pic
&& (VEFLAGS
& (X86_EFLAGS_IF
| X86_EFLAGS_VIF
))) {
735 save_v86_state(regs
, VM86_PICRETURN
);
738 if (orig_flags
& X86_EFLAGS_TF
)
739 handle_vm86_trap(regs
, 0, X86_TRAP_DB
);
743 /* FIXME: After a long discussion with Stas we finally
744 * agreed, that this is wrong. Here we should
745 * really send a SIGSEGV to the user program.
746 * But how do we create the correct context? We
747 * are inside a general protection fault handler
748 * and has just returned from a page fault handler.
749 * The correct context for the signal handler
750 * should be a mixture of the two, but how do we
751 * get the information? [KD]
753 save_v86_state(regs
, VM86_UNKNOWN
);
756 /* ---------------- vm86 special IRQ passing stuff ----------------- */
758 #define VM86_IRQNAME "vm86irq"
760 static struct vm86_irqs
{
761 struct task_struct
*tsk
;
765 static DEFINE_SPINLOCK(irqbits_lock
);
768 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \
769 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
772 static irqreturn_t
irq_handler(int intno
, void *dev_id
)
777 spin_lock_irqsave(&irqbits_lock
, flags
);
778 irq_bit
= 1 << intno
;
779 if ((irqbits
& irq_bit
) || !vm86_irqs
[intno
].tsk
)
782 if (vm86_irqs
[intno
].sig
)
783 send_sig(vm86_irqs
[intno
].sig
, vm86_irqs
[intno
].tsk
, 1);
785 * IRQ will be re-enabled when user asks for the irq (whether
786 * polling or as a result of the signal)
788 disable_irq_nosync(intno
);
789 spin_unlock_irqrestore(&irqbits_lock
, flags
);
793 spin_unlock_irqrestore(&irqbits_lock
, flags
);
797 static inline void free_vm86_irq(int irqnumber
)
801 free_irq(irqnumber
, NULL
);
802 vm86_irqs
[irqnumber
].tsk
= NULL
;
804 spin_lock_irqsave(&irqbits_lock
, flags
);
805 irqbits
&= ~(1 << irqnumber
);
806 spin_unlock_irqrestore(&irqbits_lock
, flags
);
809 void release_vm86_irqs(struct task_struct
*task
)
812 for (i
= FIRST_VM86_IRQ
; i
<= LAST_VM86_IRQ
; i
++)
813 if (vm86_irqs
[i
].tsk
== task
)
817 static inline int get_and_reset_irq(int irqnumber
)
823 if (invalid_vm86_irq(irqnumber
)) return 0;
824 if (vm86_irqs
[irqnumber
].tsk
!= current
) return 0;
825 spin_lock_irqsave(&irqbits_lock
, flags
);
826 bit
= irqbits
& (1 << irqnumber
);
829 enable_irq(irqnumber
);
833 spin_unlock_irqrestore(&irqbits_lock
, flags
);
838 static int do_vm86_irq_handling(int subfunction
, int irqnumber
)
841 switch (subfunction
) {
842 case VM86_GET_AND_RESET_IRQ
: {
843 return get_and_reset_irq(irqnumber
);
845 case VM86_GET_IRQ_BITS
: {
848 case VM86_REQUEST_IRQ
: {
849 int sig
= irqnumber
>> 8;
850 int irq
= irqnumber
& 255;
851 if (!capable(CAP_SYS_ADMIN
)) return -EPERM
;
852 if (!((1 << sig
) & ALLOWED_SIGS
)) return -EPERM
;
853 if (invalid_vm86_irq(irq
)) return -EPERM
;
854 if (vm86_irqs
[irq
].tsk
) return -EPERM
;
855 ret
= request_irq(irq
, &irq_handler
, 0, VM86_IRQNAME
, NULL
);
857 vm86_irqs
[irq
].sig
= sig
;
858 vm86_irqs
[irq
].tsk
= current
;
861 case VM86_FREE_IRQ
: {
862 if (invalid_vm86_irq(irqnumber
)) return -EPERM
;
863 if (!vm86_irqs
[irqnumber
].tsk
) return 0;
864 if (vm86_irqs
[irqnumber
].tsk
!= current
) return -EPERM
;
865 free_vm86_irq(irqnumber
);