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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
33 #include <linux/capability.h>
34 #include <linux/errno.h>
35 #include <linux/interrupt.h>
36 #include <linux/syscalls.h>
37 #include <linux/sched.h>
38 #include <linux/sched/task_stack.h>
39 #include <linux/kernel.h>
40 #include <linux/signal.h>
41 #include <linux/string.h>
43 #include <linux/smp.h>
44 #include <linux/highmem.h>
45 #include <linux/ptrace.h>
46 #include <linux/audit.h>
47 #include <linux/stddef.h>
48 #include <linux/slab.h>
49 #include <linux/security.h>
51 #include <linux/uaccess.h>
53 #include <asm/tlbflush.h>
55 #include <asm/traps.h>
61 * Interrupt handling is not guaranteed:
62 * - a real x86 will disable all interrupts for one instruction
63 * after a "mov ss,xx" to make stack handling atomic even without
64 * the 'lss' instruction. We can't guarantee this in v86 mode,
65 * as the next instruction might result in a page fault or similar.
66 * - a real x86 will have interrupts disabled for one instruction
67 * past the 'sti' that enables them. We don't bother with all the
70 * Let's hope these problems do not actually matter for anything.
75 * 8- and 16-bit register defines..
77 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0])
78 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1])
79 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip))
80 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp))
83 * virtual flags (16 and 32-bit versions)
85 #define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags))
86 #define VEFLAGS (current->thread.vm86->veflags)
88 #define set_flags(X, new, mask) \
89 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
91 #define SAFE_MASK (0xDD5)
92 #define RETURN_MASK (0xDFF)
94 void save_v86_state(struct kernel_vm86_regs *regs, int retval)
96 struct tss_struct *tss;
97 struct task_struct *tsk = current;
98 struct vm86plus_struct __user *user;
99 struct vm86 *vm86 = current->thread.vm86;
103 * This gets called from entry.S with interrupts disabled, but
104 * from process context. Enable interrupts here, before trying
105 * to access user space.
109 if (!vm86 || !vm86->user_vm86) {
110 pr_alert("no user_vm86: BAD\n");
113 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask);
114 user = vm86->user_vm86;
116 if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.is_vm86pus ?
117 sizeof(struct vm86plus_struct) :
118 sizeof(struct vm86_struct))) {
119 pr_alert("could not access userspace vm86 info\n");
124 put_user_ex(regs->pt.bx, &user->regs.ebx);
125 put_user_ex(regs->pt.cx, &user->regs.ecx);
126 put_user_ex(regs->pt.dx, &user->regs.edx);
127 put_user_ex(regs->pt.si, &user->regs.esi);
128 put_user_ex(regs->pt.di, &user->regs.edi);
129 put_user_ex(regs->pt.bp, &user->regs.ebp);
130 put_user_ex(regs->pt.ax, &user->regs.eax);
131 put_user_ex(regs->pt.ip, &user->regs.eip);
132 put_user_ex(regs->pt.cs, &user->regs.cs);
133 put_user_ex(regs->pt.flags, &user->regs.eflags);
134 put_user_ex(regs->pt.sp, &user->regs.esp);
135 put_user_ex(regs->pt.ss, &user->regs.ss);
136 put_user_ex(regs->es, &user->regs.es);
137 put_user_ex(regs->ds, &user->regs.ds);
138 put_user_ex(regs->fs, &user->regs.fs);
139 put_user_ex(regs->gs, &user->regs.gs);
141 put_user_ex(vm86->screen_bitmap, &user->screen_bitmap);
142 } put_user_catch(err);
144 pr_alert("could not access userspace vm86 info\n");
148 tss = &per_cpu(cpu_tss, get_cpu());
149 tsk->thread.sp0 = vm86->saved_sp0;
150 tsk->thread.sysenter_cs = __KERNEL_CS;
151 load_sp0(tss, &tsk->thread);
155 memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs));
157 lazy_load_gs(vm86->regs32.gs);
159 regs->pt.ax = retval;
162 static void mark_screen_rdonly(struct mm_struct *mm)
164 struct vm_area_struct *vma;
173 down_write(&mm->mmap_sem);
174 pgd = pgd_offset(mm, 0xA0000);
175 if (pgd_none_or_clear_bad(pgd))
177 p4d = p4d_offset(pgd, 0xA0000);
178 if (p4d_none_or_clear_bad(p4d))
180 pud = pud_offset(p4d, 0xA0000);
181 if (pud_none_or_clear_bad(pud))
183 pmd = pmd_offset(pud, 0xA0000);
185 if (pmd_trans_huge(*pmd)) {
186 vma = find_vma(mm, 0xA0000);
187 split_huge_pmd(vma, pmd, 0xA0000);
189 if (pmd_none_or_clear_bad(pmd))
191 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
192 for (i = 0; i < 32; i++) {
193 if (pte_present(*pte))
194 set_pte(pte, pte_wrprotect(*pte));
197 pte_unmap_unlock(pte, ptl);
199 up_write(&mm->mmap_sem);
200 flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL);
205 static int do_vm86_irq_handling(int subfunction, int irqnumber);
206 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus);
208 SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86)
210 return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false);
214 SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
217 case VM86_REQUEST_IRQ:
219 case VM86_GET_IRQ_BITS:
220 case VM86_GET_AND_RESET_IRQ:
221 return do_vm86_irq_handling(cmd, (int)arg);
222 case VM86_PLUS_INSTALL_CHECK:
224 * NOTE: on old vm86 stuff this will return the error
225 * from access_ok(), because the subfunction is
226 * interpreted as (invalid) address to vm86_struct.
227 * So the installation check works.
232 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
233 return do_sys_vm86((struct vm86plus_struct __user *) arg, true);
237 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
239 struct tss_struct *tss;
240 struct task_struct *tsk = current;
241 struct vm86 *vm86 = tsk->thread.vm86;
242 struct kernel_vm86_regs vm86regs;
243 struct pt_regs *regs = current_pt_regs();
244 unsigned long err = 0;
246 err = security_mmap_addr(0);
249 * vm86 cannot virtualize the address space, so vm86 users
250 * need to manage the low 1MB themselves using mmap. Given
251 * that BIOS places important data in the first page, vm86
252 * is essentially useless if mmap_min_addr != 0. DOSEMU,
253 * for example, won't even bother trying to use vm86 if it
254 * can't map a page at virtual address 0.
256 * To reduce the available kernel attack surface, simply
257 * disallow vm86(old) for users who cannot mmap at va 0.
259 * The implementation of security_mmap_addr will allow
260 * suitably privileged users to map va 0 even if
261 * vm.mmap_min_addr is set above 0, and we want this
262 * behavior for vm86 as well, as it ensures that legacy
263 * tools like vbetool will not fail just because of
266 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",
267 current->comm, task_pid_nr(current),
268 from_kuid_munged(&init_user_ns, current_uid()));
273 if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL)))
275 tsk->thread.vm86 = vm86;
280 if (!access_ok(VERIFY_READ, user_vm86, plus ?
281 sizeof(struct vm86_struct) :
282 sizeof(struct vm86plus_struct)))
285 memset(&vm86regs, 0, sizeof(vm86regs));
288 get_user_ex(vm86regs.pt.bx, &user_vm86->regs.ebx);
289 get_user_ex(vm86regs.pt.cx, &user_vm86->regs.ecx);
290 get_user_ex(vm86regs.pt.dx, &user_vm86->regs.edx);
291 get_user_ex(vm86regs.pt.si, &user_vm86->regs.esi);
292 get_user_ex(vm86regs.pt.di, &user_vm86->regs.edi);
293 get_user_ex(vm86regs.pt.bp, &user_vm86->regs.ebp);
294 get_user_ex(vm86regs.pt.ax, &user_vm86->regs.eax);
295 get_user_ex(vm86regs.pt.ip, &user_vm86->regs.eip);
296 get_user_ex(seg, &user_vm86->regs.cs);
297 vm86regs.pt.cs = seg;
298 get_user_ex(vm86regs.pt.flags, &user_vm86->regs.eflags);
299 get_user_ex(vm86regs.pt.sp, &user_vm86->regs.esp);
300 get_user_ex(seg, &user_vm86->regs.ss);
301 vm86regs.pt.ss = seg;
302 get_user_ex(vm86regs.es, &user_vm86->regs.es);
303 get_user_ex(vm86regs.ds, &user_vm86->regs.ds);
304 get_user_ex(vm86regs.fs, &user_vm86->regs.fs);
305 get_user_ex(vm86regs.gs, &user_vm86->regs.gs);
307 get_user_ex(vm86->flags, &user_vm86->flags);
308 get_user_ex(vm86->screen_bitmap, &user_vm86->screen_bitmap);
309 get_user_ex(vm86->cpu_type, &user_vm86->cpu_type);
310 } get_user_catch(err);
314 if (copy_from_user(&vm86->int_revectored,
315 &user_vm86->int_revectored,
316 sizeof(struct revectored_struct)))
318 if (copy_from_user(&vm86->int21_revectored,
319 &user_vm86->int21_revectored,
320 sizeof(struct revectored_struct)))
323 if (copy_from_user(&vm86->vm86plus, &user_vm86->vm86plus,
324 sizeof(struct vm86plus_info_struct)))
326 vm86->vm86plus.is_vm86pus = 1;
328 memset(&vm86->vm86plus, 0,
329 sizeof(struct vm86plus_info_struct));
331 memcpy(&vm86->regs32, regs, sizeof(struct pt_regs));
332 vm86->user_vm86 = user_vm86;
335 * The flags register is also special: we cannot trust that the user
336 * has set it up safely, so this makes sure interrupt etc flags are
337 * inherited from protected mode.
339 VEFLAGS = vm86regs.pt.flags;
340 vm86regs.pt.flags &= SAFE_MASK;
341 vm86regs.pt.flags |= regs->flags & ~SAFE_MASK;
342 vm86regs.pt.flags |= X86_VM_MASK;
344 vm86regs.pt.orig_ax = regs->orig_ax;
346 switch (vm86->cpu_type) {
348 vm86->veflags_mask = 0;
351 vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
354 vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
357 vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
364 vm86->saved_sp0 = tsk->thread.sp0;
365 lazy_save_gs(vm86->regs32.gs);
367 tss = &per_cpu(cpu_tss, get_cpu());
368 /* make room for real-mode segments */
369 tsk->thread.sp0 += 16;
371 if (static_cpu_has(X86_FEATURE_SEP))
372 tsk->thread.sysenter_cs = 0;
374 load_sp0(tss, &tsk->thread);
377 if (vm86->flags & VM86_SCREEN_BITMAP)
378 mark_screen_rdonly(tsk->mm);
380 memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs));
385 static inline void set_IF(struct kernel_vm86_regs *regs)
387 VEFLAGS |= X86_EFLAGS_VIF;
390 static inline void clear_IF(struct kernel_vm86_regs *regs)
392 VEFLAGS &= ~X86_EFLAGS_VIF;
395 static inline void clear_TF(struct kernel_vm86_regs *regs)
397 regs->pt.flags &= ~X86_EFLAGS_TF;
400 static inline void clear_AC(struct kernel_vm86_regs *regs)
402 regs->pt.flags &= ~X86_EFLAGS_AC;
406 * It is correct to call set_IF(regs) from the set_vflags_*
407 * functions. However someone forgot to call clear_IF(regs)
408 * in the opposite case.
409 * After the command sequence CLI PUSHF STI POPF you should
410 * end up with interrupts disabled, but you ended up with
411 * interrupts enabled.
412 * ( I was testing my own changes, but the only bug I
413 * could find was in a function I had not changed. )
417 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs)
419 set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask);
420 set_flags(regs->pt.flags, flags, SAFE_MASK);
421 if (flags & X86_EFLAGS_IF)
427 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs)
429 set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask);
430 set_flags(regs->pt.flags, flags, SAFE_MASK);
431 if (flags & X86_EFLAGS_IF)
437 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs)
439 unsigned long flags = regs->pt.flags & RETURN_MASK;
441 if (VEFLAGS & X86_EFLAGS_VIF)
442 flags |= X86_EFLAGS_IF;
443 flags |= X86_EFLAGS_IOPL;
444 return flags | (VEFLAGS & current->thread.vm86->veflags_mask);
447 static inline int is_revectored(int nr, struct revectored_struct *bitmap)
449 return test_bit(nr, bitmap->__map);
452 #define val_byte(val, n) (((__u8 *)&val)[n])
454 #define pushb(base, ptr, val, err_label) \
458 if (put_user(__val, base + ptr) < 0) \
462 #define pushw(base, ptr, val, err_label) \
466 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
469 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
473 #define pushl(base, ptr, val, err_label) \
477 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
480 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
483 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
486 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
490 #define popb(base, ptr, err_label) \
493 if (get_user(__res, base + ptr) < 0) \
499 #define popw(base, ptr, err_label) \
502 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
505 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
511 #define popl(base, ptr, err_label) \
514 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
517 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
520 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
523 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
529 /* There are so many possible reasons for this function to return
530 * VM86_INTx, so adding another doesn't bother me. We can expect
531 * userspace programs to be able to handle it. (Getting a problem
532 * in userspace is always better than an Oops anyway.) [KD]
534 static void do_int(struct kernel_vm86_regs *regs, int i,
535 unsigned char __user *ssp, unsigned short sp)
537 unsigned long __user *intr_ptr;
538 unsigned long segoffs;
539 struct vm86 *vm86 = current->thread.vm86;
541 if (regs->pt.cs == BIOSSEG)
543 if (is_revectored(i, &vm86->int_revectored))
545 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored))
547 intr_ptr = (unsigned long __user *) (i << 2);
548 if (get_user(segoffs, intr_ptr))
550 if ((segoffs >> 16) == BIOSSEG)
552 pushw(ssp, sp, get_vflags(regs), cannot_handle);
553 pushw(ssp, sp, regs->pt.cs, cannot_handle);
554 pushw(ssp, sp, IP(regs), cannot_handle);
555 regs->pt.cs = segoffs >> 16;
557 IP(regs) = segoffs & 0xffff;
564 save_v86_state(regs, VM86_INTx + (i << 8));
567 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno)
569 struct vm86 *vm86 = current->thread.vm86;
571 if (vm86->vm86plus.is_vm86pus) {
572 if ((trapno == 3) || (trapno == 1)) {
573 save_v86_state(regs, VM86_TRAP + (trapno << 8));
576 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs));
580 return 1; /* we let this handle by the calling routine */
581 current->thread.trap_nr = trapno;
582 current->thread.error_code = error_code;
583 force_sig(SIGTRAP, current);
587 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code)
589 unsigned char opcode;
590 unsigned char __user *csp;
591 unsigned char __user *ssp;
592 unsigned short ip, sp, orig_flags;
593 int data32, pref_done;
594 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus;
596 #define CHECK_IF_IN_TRAP \
597 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \
598 newflags |= X86_EFLAGS_TF
600 orig_flags = *(unsigned short *)®s->pt.flags;
602 csp = (unsigned char __user *) (regs->pt.cs << 4);
603 ssp = (unsigned char __user *) (regs->pt.ss << 4);
610 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
611 case 0x66: /* 32-bit data */ data32 = 1; break;
612 case 0x67: /* 32-bit address */ break;
613 case 0x2e: /* CS */ break;
614 case 0x3e: /* DS */ break;
615 case 0x26: /* ES */ break;
616 case 0x36: /* SS */ break;
617 case 0x65: /* GS */ break;
618 case 0x64: /* FS */ break;
619 case 0xf2: /* repnz */ break;
620 case 0xf3: /* rep */ break;
621 default: pref_done = 1;
623 } while (!pref_done);
630 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
633 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
637 goto vm86_fault_return;
642 unsigned long newflags;
644 newflags = popl(ssp, sp, simulate_sigsegv);
647 newflags = popw(ssp, sp, simulate_sigsegv);
653 set_vflags_long(newflags, regs);
655 set_vflags_short(newflags, regs);
662 int intno = popb(csp, ip, simulate_sigsegv);
664 if (vmpi->vm86dbg_active) {
665 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) {
666 save_v86_state(regs, VM86_INTx + (intno << 8));
670 do_int(regs, intno, ssp, sp);
679 unsigned long newflags;
681 newip = popl(ssp, sp, simulate_sigsegv);
682 newcs = popl(ssp, sp, simulate_sigsegv);
683 newflags = popl(ssp, sp, simulate_sigsegv);
686 newip = popw(ssp, sp, simulate_sigsegv);
687 newcs = popw(ssp, sp, simulate_sigsegv);
688 newflags = popw(ssp, sp, simulate_sigsegv);
695 set_vflags_long(newflags, regs);
697 set_vflags_short(newflags, regs);
706 goto vm86_fault_return;
710 * Damn. This is incorrect: the 'sti' instruction should actually
711 * enable interrupts after the /next/ instruction. Not good.
713 * Probably needs some horsing around with the TF flag. Aiee..
721 save_v86_state(regs, VM86_UNKNOWN);
727 if (VEFLAGS & X86_EFLAGS_VIP) {
728 save_v86_state(regs, VM86_STI);
733 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) {
734 save_v86_state(regs, VM86_PICRETURN);
737 if (orig_flags & X86_EFLAGS_TF)
738 handle_vm86_trap(regs, 0, X86_TRAP_DB);
742 /* FIXME: After a long discussion with Stas we finally
743 * agreed, that this is wrong. Here we should
744 * really send a SIGSEGV to the user program.
745 * But how do we create the correct context? We
746 * are inside a general protection fault handler
747 * and has just returned from a page fault handler.
748 * The correct context for the signal handler
749 * should be a mixture of the two, but how do we
750 * get the information? [KD]
752 save_v86_state(regs, VM86_UNKNOWN);
755 /* ---------------- vm86 special IRQ passing stuff ----------------- */
757 #define VM86_IRQNAME "vm86irq"
759 static struct vm86_irqs {
760 struct task_struct *tsk;
764 static DEFINE_SPINLOCK(irqbits_lock);
767 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \
768 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
771 static irqreturn_t irq_handler(int intno, void *dev_id)
776 spin_lock_irqsave(&irqbits_lock, flags);
777 irq_bit = 1 << intno;
778 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk)
781 if (vm86_irqs[intno].sig)
782 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
784 * IRQ will be re-enabled when user asks for the irq (whether
785 * polling or as a result of the signal)
787 disable_irq_nosync(intno);
788 spin_unlock_irqrestore(&irqbits_lock, flags);
792 spin_unlock_irqrestore(&irqbits_lock, flags);
796 static inline void free_vm86_irq(int irqnumber)
800 free_irq(irqnumber, NULL);
801 vm86_irqs[irqnumber].tsk = NULL;
803 spin_lock_irqsave(&irqbits_lock, flags);
804 irqbits &= ~(1 << irqnumber);
805 spin_unlock_irqrestore(&irqbits_lock, flags);
808 void release_vm86_irqs(struct task_struct *task)
811 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
812 if (vm86_irqs[i].tsk == task)
816 static inline int get_and_reset_irq(int irqnumber)
822 if (invalid_vm86_irq(irqnumber)) return 0;
823 if (vm86_irqs[irqnumber].tsk != current) return 0;
824 spin_lock_irqsave(&irqbits_lock, flags);
825 bit = irqbits & (1 << irqnumber);
828 enable_irq(irqnumber);
832 spin_unlock_irqrestore(&irqbits_lock, flags);
837 static int do_vm86_irq_handling(int subfunction, int irqnumber)
840 switch (subfunction) {
841 case VM86_GET_AND_RESET_IRQ: {
842 return get_and_reset_irq(irqnumber);
844 case VM86_GET_IRQ_BITS: {
847 case VM86_REQUEST_IRQ: {
848 int sig = irqnumber >> 8;
849 int irq = irqnumber & 255;
850 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
851 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
852 if (invalid_vm86_irq(irq)) return -EPERM;
853 if (vm86_irqs[irq].tsk) return -EPERM;
854 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL);
856 vm86_irqs[irq].sig = sig;
857 vm86_irqs[irq].tsk = current;
860 case VM86_FREE_IRQ: {
861 if (invalid_vm86_irq(irqnumber)) return -EPERM;
862 if (!vm86_irqs[irqnumber].tsk) return 0;
863 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
864 free_vm86_irq(irqnumber);