[CRYPTO] api: Remove deprecated interface
[pv_ops_mirror.git] / arch / i386 / kernel / vm86.c
blobbe2f96e67f78d80c51ba6c1b9a5fde49563ff415
1 /*
2 * linux/kernel/vm86.c
4 * Copyright (C) 1994 Linus Torvalds
6 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
7 * stack - Manfred Spraul <manfred@colorfullife.com>
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>
14 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
15 * <kasperd@daimi.au.dk>
17 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
18 * caused by Kasper Dupont's changes - Stas Sergeev
20 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
21 * Kasper Dupont <kasperd@daimi.au.dk>
23 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
24 * Kasper Dupont <kasperd@daimi.au.dk>
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>
33 #include <linux/capability.h>
34 #include <linux/errno.h>
35 #include <linux/interrupt.h>
36 #include <linux/sched.h>
37 #include <linux/kernel.h>
38 #include <linux/signal.h>
39 #include <linux/string.h>
40 #include <linux/mm.h>
41 #include <linux/smp.h>
42 #include <linux/smp_lock.h>
43 #include <linux/highmem.h>
44 #include <linux/ptrace.h>
45 #include <linux/audit.h>
46 #include <linux/stddef.h>
48 #include <asm/uaccess.h>
49 #include <asm/io.h>
50 #include <asm/tlbflush.h>
51 #include <asm/irq.h>
54 * Known problems:
56 * Interrupt handling is not guaranteed:
57 * - a real x86 will disable all interrupts for one instruction
58 * after a "mov ss,xx" to make stack handling atomic even without
59 * the 'lss' instruction. We can't guarantee this in v86 mode,
60 * as the next instruction might result in a page fault or similar.
61 * - a real x86 will have interrupts disabled for one instruction
62 * past the 'sti' that enables them. We don't bother with all the
63 * details yet.
65 * Let's hope these problems do not actually matter for anything.
69 #define KVM86 ((struct kernel_vm86_struct *)regs)
70 #define VMPI KVM86->vm86plus
74 * 8- and 16-bit register defines..
76 #define AL(regs) (((unsigned char *)&((regs)->pt.eax))[0])
77 #define AH(regs) (((unsigned char *)&((regs)->pt.eax))[1])
78 #define IP(regs) (*(unsigned short *)&((regs)->pt.eip))
79 #define SP(regs) (*(unsigned short *)&((regs)->pt.esp))
82 * virtual flags (16 and 32-bit versions)
84 #define VFLAGS (*(unsigned short *)&(current->thread.v86flags))
85 #define VEFLAGS (current->thread.v86flags)
87 #define set_flags(X,new,mask) \
88 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
90 #define SAFE_MASK (0xDD5)
91 #define RETURN_MASK (0xDFF)
93 /* convert kernel_vm86_regs to vm86_regs */
94 static int copy_vm86_regs_to_user(struct vm86_regs __user *user,
95 const struct kernel_vm86_regs *regs)
97 int ret = 0;
99 /* kernel_vm86_regs is missing xfs, so copy everything up to
100 (but not including) xgs, and then rest after xgs. */
101 ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.xgs));
102 ret += copy_to_user(&user->__null_gs, &regs->pt.xgs,
103 sizeof(struct kernel_vm86_regs) -
104 offsetof(struct kernel_vm86_regs, pt.xgs));
106 return ret;
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,
112 unsigned extra)
114 int ret = 0;
116 ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.xgs));
117 ret += copy_from_user(&regs->pt.xgs, &user->__null_gs,
118 sizeof(struct kernel_vm86_regs) -
119 offsetof(struct kernel_vm86_regs, pt.xgs) +
120 extra);
122 return ret;
125 struct pt_regs * FASTCALL(save_v86_state(struct kernel_vm86_regs * regs));
126 struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs)
128 struct tss_struct *tss;
129 struct pt_regs *ret;
130 unsigned long tmp;
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.
137 local_irq_enable();
139 if (!current->thread.vm86_info) {
140 printk("no vm86_info: BAD\n");
141 do_exit(SIGSEGV);
143 set_flags(regs->pt.eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);
144 tmp = copy_vm86_regs_to_user(&current->thread.vm86_info->regs,regs);
145 tmp += put_user(current->thread.screen_bitmap,&current->thread.vm86_info->screen_bitmap);
146 if (tmp) {
147 printk("vm86: could not access userspace vm86_info\n");
148 do_exit(SIGSEGV);
151 tss = &per_cpu(init_tss, get_cpu());
152 current->thread.esp0 = current->thread.saved_esp0;
153 current->thread.sysenter_cs = __KERNEL_CS;
154 load_esp0(tss, &current->thread);
155 current->thread.saved_esp0 = 0;
156 put_cpu();
158 ret = KVM86->regs32;
160 loadsegment(fs, current->thread.saved_fs);
161 ret->xgs = current->thread.saved_gs;
163 return ret;
166 static void mark_screen_rdonly(struct mm_struct *mm)
168 pgd_t *pgd;
169 pud_t *pud;
170 pmd_t *pmd;
171 pte_t *pte;
172 spinlock_t *ptl;
173 int i;
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++;
190 pte_unmap_unlock(pte, ptl);
191 out:
192 flush_tlb();
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.ebx;
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;
211 tsk = current;
212 if (tsk->thread.saved_esp0)
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 = &regs;
222 tsk->thread.vm86_info = v86;
223 do_sys_vm86(&info, tsk);
224 ret = 0; /* we never return here */
225 out:
226 return ret;
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;
238 int tmp, ret;
239 struct vm86plus_struct __user *v86;
241 tsk = current;
242 switch (regs.ebx) {
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.ebx, (int)regs.ecx);
248 goto out;
249 case VM86_PLUS_INSTALL_CHECK:
250 /* NOTE: on old vm86 stuff this will return the error
251 from access_ok(), because the subfunction is
252 interpreted as (invalid) address to vm86_struct.
253 So the installation check works.
255 ret = 0;
256 goto out;
259 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
260 ret = -EPERM;
261 if (tsk->thread.saved_esp0)
262 goto out;
263 v86 = (struct vm86plus_struct __user *)regs.ecx;
264 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
265 offsetof(struct kernel_vm86_struct, regs32) -
266 sizeof(info.regs));
267 ret = -EFAULT;
268 if (tmp)
269 goto out;
270 info.regs32 = &regs;
271 info.vm86plus.is_vm86pus = 1;
272 tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
273 do_sys_vm86(&info, tsk);
274 ret = 0; /* we never return here */
275 out:
276 return ret;
280 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
282 struct tss_struct *tss;
284 * make sure the vm86() system call doesn't try to do anything silly
286 info->regs.pt.xds = 0;
287 info->regs.pt.xes = 0;
288 info->regs.pt.xgs = 0;
290 /* we are clearing fs later just before "jmp resume_userspace",
291 * because it is not saved/restored.
295 * The eflags register is also special: we cannot trust that the user
296 * has set it up safely, so this makes sure interrupt etc flags are
297 * inherited from protected mode.
299 VEFLAGS = info->regs.pt.eflags;
300 info->regs.pt.eflags &= SAFE_MASK;
301 info->regs.pt.eflags |= info->regs32->eflags & ~SAFE_MASK;
302 info->regs.pt.eflags |= VM_MASK;
304 switch (info->cpu_type) {
305 case CPU_286:
306 tsk->thread.v86mask = 0;
307 break;
308 case CPU_386:
309 tsk->thread.v86mask = NT_MASK | IOPL_MASK;
310 break;
311 case CPU_486:
312 tsk->thread.v86mask = AC_MASK | NT_MASK | IOPL_MASK;
313 break;
314 default:
315 tsk->thread.v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
316 break;
320 * Save old state, set default return value (%eax) to 0
322 info->regs32->eax = 0;
323 tsk->thread.saved_esp0 = tsk->thread.esp0;
324 savesegment(fs, tsk->thread.saved_fs);
325 tsk->thread.saved_gs = info->regs32->xgs;
327 tss = &per_cpu(init_tss, get_cpu());
328 tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0;
329 if (cpu_has_sep)
330 tsk->thread.sysenter_cs = 0;
331 load_esp0(tss, &tsk->thread);
332 put_cpu();
334 tsk->thread.screen_bitmap = info->screen_bitmap;
335 if (info->flags & VM86_SCREEN_BITMAP)
336 mark_screen_rdonly(tsk->mm);
338 /*call audit_syscall_exit since we do not exit via the normal paths */
339 if (unlikely(current->audit_context))
340 audit_syscall_exit(AUDITSC_RESULT(0), 0);
342 __asm__ __volatile__(
343 "movl %0,%%esp\n\t"
344 "movl %1,%%ebp\n\t"
345 "mov %2, %%fs\n\t"
346 "jmp resume_userspace"
347 : /* no outputs */
348 :"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0));
349 /* we never return here */
352 static inline void return_to_32bit(struct kernel_vm86_regs * regs16, int retval)
354 struct pt_regs * regs32;
356 regs32 = save_v86_state(regs16);
357 regs32->eax = retval;
358 __asm__ __volatile__("movl %0,%%esp\n\t"
359 "movl %1,%%ebp\n\t"
360 "jmp resume_userspace"
361 : : "r" (regs32), "r" (current_thread_info()));
364 static inline void set_IF(struct kernel_vm86_regs * regs)
366 VEFLAGS |= VIF_MASK;
367 if (VEFLAGS & VIP_MASK)
368 return_to_32bit(regs, VM86_STI);
371 static inline void clear_IF(struct kernel_vm86_regs * regs)
373 VEFLAGS &= ~VIF_MASK;
376 static inline void clear_TF(struct kernel_vm86_regs * regs)
378 regs->pt.eflags &= ~TF_MASK;
381 static inline void clear_AC(struct kernel_vm86_regs * regs)
383 regs->pt.eflags &= ~AC_MASK;
386 /* It is correct to call set_IF(regs) from the set_vflags_*
387 * functions. However someone forgot to call clear_IF(regs)
388 * in the opposite case.
389 * After the command sequence CLI PUSHF STI POPF you should
390 * end up with interrups disabled, but you ended up with
391 * interrupts enabled.
392 * ( I was testing my own changes, but the only bug I
393 * could find was in a function I had not changed. )
394 * [KD]
397 static inline void set_vflags_long(unsigned long eflags, struct kernel_vm86_regs * regs)
399 set_flags(VEFLAGS, eflags, current->thread.v86mask);
400 set_flags(regs->pt.eflags, eflags, SAFE_MASK);
401 if (eflags & IF_MASK)
402 set_IF(regs);
403 else
404 clear_IF(regs);
407 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs * regs)
409 set_flags(VFLAGS, flags, current->thread.v86mask);
410 set_flags(regs->pt.eflags, flags, SAFE_MASK);
411 if (flags & IF_MASK)
412 set_IF(regs);
413 else
414 clear_IF(regs);
417 static inline unsigned long get_vflags(struct kernel_vm86_regs * regs)
419 unsigned long flags = regs->pt.eflags & RETURN_MASK;
421 if (VEFLAGS & VIF_MASK)
422 flags |= IF_MASK;
423 flags |= IOPL_MASK;
424 return flags | (VEFLAGS & current->thread.v86mask);
427 static inline int is_revectored(int nr, struct revectored_struct * bitmap)
429 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
430 :"=r" (nr)
431 :"m" (*bitmap),"r" (nr));
432 return nr;
435 #define val_byte(val, n) (((__u8 *)&val)[n])
437 #define pushb(base, ptr, val, err_label) \
438 do { \
439 __u8 __val = val; \
440 ptr--; \
441 if (put_user(__val, base + ptr) < 0) \
442 goto err_label; \
443 } while(0)
445 #define pushw(base, ptr, val, err_label) \
446 do { \
447 __u16 __val = val; \
448 ptr--; \
449 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
450 goto err_label; \
451 ptr--; \
452 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
453 goto err_label; \
454 } while(0)
456 #define pushl(base, ptr, val, err_label) \
457 do { \
458 __u32 __val = val; \
459 ptr--; \
460 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
461 goto err_label; \
462 ptr--; \
463 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
464 goto err_label; \
465 ptr--; \
466 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
467 goto err_label; \
468 ptr--; \
469 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
470 goto err_label; \
471 } while(0)
473 #define popb(base, ptr, err_label) \
474 ({ \
475 __u8 __res; \
476 if (get_user(__res, base + ptr) < 0) \
477 goto err_label; \
478 ptr++; \
479 __res; \
482 #define popw(base, ptr, err_label) \
483 ({ \
484 __u16 __res; \
485 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
486 goto err_label; \
487 ptr++; \
488 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
489 goto err_label; \
490 ptr++; \
491 __res; \
494 #define popl(base, ptr, err_label) \
495 ({ \
496 __u32 __res; \
497 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
498 goto err_label; \
499 ptr++; \
500 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
501 goto err_label; \
502 ptr++; \
503 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
504 goto err_label; \
505 ptr++; \
506 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
507 goto err_label; \
508 ptr++; \
509 __res; \
512 /* There are so many possible reasons for this function to return
513 * VM86_INTx, so adding another doesn't bother me. We can expect
514 * userspace programs to be able to handle it. (Getting a problem
515 * in userspace is always better than an Oops anyway.) [KD]
517 static void do_int(struct kernel_vm86_regs *regs, int i,
518 unsigned char __user * ssp, unsigned short sp)
520 unsigned long __user *intr_ptr;
521 unsigned long segoffs;
523 if (regs->pt.xcs == BIOSSEG)
524 goto cannot_handle;
525 if (is_revectored(i, &KVM86->int_revectored))
526 goto cannot_handle;
527 if (i==0x21 && is_revectored(AH(regs),&KVM86->int21_revectored))
528 goto cannot_handle;
529 intr_ptr = (unsigned long __user *) (i << 2);
530 if (get_user(segoffs, intr_ptr))
531 goto cannot_handle;
532 if ((segoffs >> 16) == BIOSSEG)
533 goto cannot_handle;
534 pushw(ssp, sp, get_vflags(regs), cannot_handle);
535 pushw(ssp, sp, regs->pt.xcs, cannot_handle);
536 pushw(ssp, sp, IP(regs), cannot_handle);
537 regs->pt.xcs = segoffs >> 16;
538 SP(regs) -= 6;
539 IP(regs) = segoffs & 0xffff;
540 clear_TF(regs);
541 clear_IF(regs);
542 clear_AC(regs);
543 return;
545 cannot_handle:
546 return_to_32bit(regs, VM86_INTx + (i << 8));
549 int handle_vm86_trap(struct kernel_vm86_regs * regs, long error_code, int trapno)
551 if (VMPI.is_vm86pus) {
552 if ( (trapno==3) || (trapno==1) )
553 return_to_32bit(regs, VM86_TRAP + (trapno << 8));
554 do_int(regs, trapno, (unsigned char __user *) (regs->pt.xss << 4), SP(regs));
555 return 0;
557 if (trapno !=1)
558 return 1; /* we let this handle by the calling routine */
559 if (current->ptrace & PT_PTRACED) {
560 unsigned long flags;
561 spin_lock_irqsave(&current->sighand->siglock, flags);
562 sigdelset(&current->blocked, SIGTRAP);
563 recalc_sigpending();
564 spin_unlock_irqrestore(&current->sighand->siglock, flags);
566 send_sig(SIGTRAP, current, 1);
567 current->thread.trap_no = trapno;
568 current->thread.error_code = error_code;
569 return 0;
572 void handle_vm86_fault(struct kernel_vm86_regs * regs, long error_code)
574 unsigned char opcode;
575 unsigned char __user *csp;
576 unsigned char __user *ssp;
577 unsigned short ip, sp, orig_flags;
578 int data32, pref_done;
580 #define CHECK_IF_IN_TRAP \
581 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
582 newflags |= TF_MASK
583 #define VM86_FAULT_RETURN do { \
584 if (VMPI.force_return_for_pic && (VEFLAGS & (IF_MASK | VIF_MASK))) \
585 return_to_32bit(regs, VM86_PICRETURN); \
586 if (orig_flags & TF_MASK) \
587 handle_vm86_trap(regs, 0, 1); \
588 return; } while (0)
590 orig_flags = *(unsigned short *)&regs->pt.eflags;
592 csp = (unsigned char __user *) (regs->pt.xcs << 4);
593 ssp = (unsigned char __user *) (regs->pt.xss << 4);
594 sp = SP(regs);
595 ip = IP(regs);
597 data32 = 0;
598 pref_done = 0;
599 do {
600 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
601 case 0x66: /* 32-bit data */ data32=1; break;
602 case 0x67: /* 32-bit address */ break;
603 case 0x2e: /* CS */ break;
604 case 0x3e: /* DS */ break;
605 case 0x26: /* ES */ break;
606 case 0x36: /* SS */ break;
607 case 0x65: /* GS */ break;
608 case 0x64: /* FS */ break;
609 case 0xf2: /* repnz */ break;
610 case 0xf3: /* rep */ break;
611 default: pref_done = 1;
613 } while (!pref_done);
615 switch (opcode) {
617 /* pushf */
618 case 0x9c:
619 if (data32) {
620 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
621 SP(regs) -= 4;
622 } else {
623 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
624 SP(regs) -= 2;
626 IP(regs) = ip;
627 VM86_FAULT_RETURN;
629 /* popf */
630 case 0x9d:
632 unsigned long newflags;
633 if (data32) {
634 newflags=popl(ssp, sp, simulate_sigsegv);
635 SP(regs) += 4;
636 } else {
637 newflags = popw(ssp, sp, simulate_sigsegv);
638 SP(regs) += 2;
640 IP(regs) = ip;
641 CHECK_IF_IN_TRAP;
642 if (data32) {
643 set_vflags_long(newflags, regs);
644 } else {
645 set_vflags_short(newflags, regs);
647 VM86_FAULT_RETURN;
650 /* int xx */
651 case 0xcd: {
652 int intno=popb(csp, ip, simulate_sigsegv);
653 IP(regs) = ip;
654 if (VMPI.vm86dbg_active) {
655 if ( (1 << (intno &7)) & VMPI.vm86dbg_intxxtab[intno >> 3] )
656 return_to_32bit(regs, VM86_INTx + (intno << 8));
658 do_int(regs, intno, ssp, sp);
659 return;
662 /* iret */
663 case 0xcf:
665 unsigned long newip;
666 unsigned long newcs;
667 unsigned long newflags;
668 if (data32) {
669 newip=popl(ssp, sp, simulate_sigsegv);
670 newcs=popl(ssp, sp, simulate_sigsegv);
671 newflags=popl(ssp, sp, simulate_sigsegv);
672 SP(regs) += 12;
673 } else {
674 newip = popw(ssp, sp, simulate_sigsegv);
675 newcs = popw(ssp, sp, simulate_sigsegv);
676 newflags = popw(ssp, sp, simulate_sigsegv);
677 SP(regs) += 6;
679 IP(regs) = newip;
680 regs->pt.xcs = newcs;
681 CHECK_IF_IN_TRAP;
682 if (data32) {
683 set_vflags_long(newflags, regs);
684 } else {
685 set_vflags_short(newflags, regs);
687 VM86_FAULT_RETURN;
690 /* cli */
691 case 0xfa:
692 IP(regs) = ip;
693 clear_IF(regs);
694 VM86_FAULT_RETURN;
696 /* sti */
698 * Damn. This is incorrect: the 'sti' instruction should actually
699 * enable interrupts after the /next/ instruction. Not good.
701 * Probably needs some horsing around with the TF flag. Aiee..
703 case 0xfb:
704 IP(regs) = ip;
705 set_IF(regs);
706 VM86_FAULT_RETURN;
708 default:
709 return_to_32bit(regs, VM86_UNKNOWN);
712 return;
714 simulate_sigsegv:
715 /* FIXME: After a long discussion with Stas we finally
716 * agreed, that this is wrong. Here we should
717 * really send a SIGSEGV to the user program.
718 * But how do we create the correct context? We
719 * are inside a general protection fault handler
720 * and has just returned from a page fault handler.
721 * The correct context for the signal handler
722 * should be a mixture of the two, but how do we
723 * get the information? [KD]
725 return_to_32bit(regs, VM86_UNKNOWN);
728 /* ---------------- vm86 special IRQ passing stuff ----------------- */
730 #define VM86_IRQNAME "vm86irq"
732 static struct vm86_irqs {
733 struct task_struct *tsk;
734 int sig;
735 } vm86_irqs[16];
737 static DEFINE_SPINLOCK(irqbits_lock);
738 static int irqbits;
740 #define ALLOWED_SIGS ( 1 /* 0 = don't send a signal */ \
741 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
742 | (1 << SIGUNUSED) )
744 static irqreturn_t irq_handler(int intno, void *dev_id)
746 int irq_bit;
747 unsigned long flags;
749 spin_lock_irqsave(&irqbits_lock, flags);
750 irq_bit = 1 << intno;
751 if ((irqbits & irq_bit) || ! vm86_irqs[intno].tsk)
752 goto out;
753 irqbits |= irq_bit;
754 if (vm86_irqs[intno].sig)
755 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
757 * IRQ will be re-enabled when user asks for the irq (whether
758 * polling or as a result of the signal)
760 disable_irq_nosync(intno);
761 spin_unlock_irqrestore(&irqbits_lock, flags);
762 return IRQ_HANDLED;
764 out:
765 spin_unlock_irqrestore(&irqbits_lock, flags);
766 return IRQ_NONE;
769 static inline void free_vm86_irq(int irqnumber)
771 unsigned long flags;
773 free_irq(irqnumber, NULL);
774 vm86_irqs[irqnumber].tsk = NULL;
776 spin_lock_irqsave(&irqbits_lock, flags);
777 irqbits &= ~(1 << irqnumber);
778 spin_unlock_irqrestore(&irqbits_lock, flags);
781 void release_vm86_irqs(struct task_struct *task)
783 int i;
784 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
785 if (vm86_irqs[i].tsk == task)
786 free_vm86_irq(i);
789 static inline int get_and_reset_irq(int irqnumber)
791 int bit;
792 unsigned long flags;
793 int ret = 0;
795 if (invalid_vm86_irq(irqnumber)) return 0;
796 if (vm86_irqs[irqnumber].tsk != current) return 0;
797 spin_lock_irqsave(&irqbits_lock, flags);
798 bit = irqbits & (1 << irqnumber);
799 irqbits &= ~bit;
800 if (bit) {
801 enable_irq(irqnumber);
802 ret = 1;
805 spin_unlock_irqrestore(&irqbits_lock, flags);
806 return ret;
810 static int do_vm86_irq_handling(int subfunction, int irqnumber)
812 int ret;
813 switch (subfunction) {
814 case VM86_GET_AND_RESET_IRQ: {
815 return get_and_reset_irq(irqnumber);
817 case VM86_GET_IRQ_BITS: {
818 return irqbits;
820 case VM86_REQUEST_IRQ: {
821 int sig = irqnumber >> 8;
822 int irq = irqnumber & 255;
823 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
824 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
825 if (invalid_vm86_irq(irq)) return -EPERM;
826 if (vm86_irqs[irq].tsk) return -EPERM;
827 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL);
828 if (ret) return ret;
829 vm86_irqs[irq].sig = sig;
830 vm86_irqs[irq].tsk = current;
831 return irq;
833 case VM86_FREE_IRQ: {
834 if (invalid_vm86_irq(irqnumber)) return -EPERM;
835 if (!vm86_irqs[irqnumber].tsk) return 0;
836 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
837 free_vm86_irq(irqnumber);
838 return 0;
841 return -EINVAL;