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[net-next-2.6.git] / arch / i386 / kernel / vm86.c
CommitLineData
1da177e4
LT		 1/*
2 * linux/kernel/vm86.c
3 *
4 * Copyright (C) 1994 Linus Torvalds
5 *
6 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
7 * stack - Manfred Spraul <manfreds@colorfullife.com>
8 *
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>
13 *
14 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
15 * <kasperd@daimi.au.dk>
16 *
17 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
18 * caused by Kasper Dupont's changes - Stas Sergeev
19 *
20 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
21 * Kasper Dupont <kasperd@daimi.au.dk>
22 *
23 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
24 * Kasper Dupont <kasperd@daimi.au.dk>
25 *
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>
30 *
31 */
32
33#include <linux/config.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
46#include <asm/uaccess.h>
47#include <asm/io.h>
48#include <asm/tlbflush.h>
49#include <asm/irq.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)->eax))[0])
75#define AH(regs) (((unsigned char *)&((regs)->eax))[1])
76#define IP(regs) (*(unsigned short *)&((regs)->eip))
77#define SP(regs) (*(unsigned short *)&((regs)->esp))
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#define VM86_REGS_PART2 orig_eax
92#define VM86_REGS_SIZE1 \
93 ( (unsigned)( & (((struct kernel_vm86_regs *)0)->VM86_REGS_PART2) ) )
94#define VM86_REGS_SIZE2 (sizeof(struct kernel_vm86_regs) - VM86_REGS_SIZE1)
95
96struct pt_regs * FASTCALL(save_v86_state(struct kernel_vm86_regs * regs));
97struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs)
98{
99 struct tss_struct *tss;
100 struct pt_regs *ret;
101 unsigned long tmp;
102
103 /*
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.
107 */
108 local_irq_enable();
109
110 if (!current->thread.vm86_info) {
111 printk("no vm86_info: BAD\n");
112 do_exit(SIGSEGV);
113 }
114 set_flags(regs->eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);
115 tmp = copy_to_user(&current->thread.vm86_info->regs,regs, VM86_REGS_SIZE1);
116 tmp += copy_to_user(&current->thread.vm86_info->regs.VM86_REGS_PART2,
117 &regs->VM86_REGS_PART2, VM86_REGS_SIZE2);
118 tmp += put_user(current->thread.screen_bitmap,&current->thread.vm86_info->screen_bitmap);
119 if (tmp) {
120 printk("vm86: could not access userspace vm86_info\n");
121 do_exit(SIGSEGV);
122 }
123
124 tss = &per_cpu(init_tss, get_cpu());
125 current->thread.esp0 = current->thread.saved_esp0;
126 current->thread.sysenter_cs = __KERNEL_CS;
127 load_esp0(tss, &current->thread);
128 current->thread.saved_esp0 = 0;
129 put_cpu();
130
131 loadsegment(fs, current->thread.saved_fs);
132 loadsegment(gs, current->thread.saved_gs);
133 ret = KVM86->regs32;
134 return ret;
135}
136
137static void mark_screen_rdonly(struct task_struct * tsk)
138{
139 pgd_t *pgd;
140 pud_t *pud;
141 pmd_t *pmd;
142 pte_t *pte, *mapped;
143 int i;
144
145 preempt_disable();
146 spin_lock(&tsk->mm->page_table_lock);
147 pgd = pgd_offset(tsk->mm, 0xA0000);
148 if (pgd_none_or_clear_bad(pgd))
149 goto out;
150 pud = pud_offset(pgd, 0xA0000);
151 if (pud_none_or_clear_bad(pud))
152 goto out;
153 pmd = pmd_offset(pud, 0xA0000);
154 if (pmd_none_or_clear_bad(pmd))
155 goto out;
156 pte = mapped = pte_offset_map(pmd, 0xA0000);
157 for (i = 0; i < 32; i++) {
158 if (pte_present(*pte))
159 set_pte(pte, pte_wrprotect(*pte));
160 pte++;
161 }
162 pte_unmap(mapped);
163out:
164 spin_unlock(&tsk->mm->page_table_lock);
165 preempt_enable();
166 flush_tlb();
167}
168
169
170
171static int do_vm86_irq_handling(int subfunction, int irqnumber);
172static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
173
174asmlinkage int sys_vm86old(struct pt_regs regs)
175{
176 struct vm86_struct __user *v86 = (struct vm86_struct __user *)regs.ebx;
177 struct kernel_vm86_struct info; /* declare this _on top_,
178 * this avoids wasting of stack space.
179 * This remains on the stack until we
180 * return to 32 bit user space.
181 */
182 struct task_struct *tsk;
183 int tmp, ret = -EPERM;
184
185 tsk = current;
186 if (tsk->thread.saved_esp0)
187 goto out;
188 tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
189 tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
190 (long)&info.vm86plus - (long)&info.regs.VM86_REGS_PART2);
191 ret = -EFAULT;
192 if (tmp)
193 goto out;
194 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
195 info.regs32 = &regs;
196 tsk->thread.vm86_info = v86;
197 do_sys_vm86(&info, tsk);
198 ret = 0; /* we never return here */
199out:
200 return ret;
201}
202
203
204asmlinkage int sys_vm86(struct pt_regs regs)
205{
206 struct kernel_vm86_struct info; /* declare this _on top_,
207 * this avoids wasting of stack space.
208 * This remains on the stack until we
209 * return to 32 bit user space.
210 */
211 struct task_struct *tsk;
212 int tmp, ret;
213 struct vm86plus_struct __user *v86;
214
215 tsk = current;
216 switch (regs.ebx) {
217 case VM86_REQUEST_IRQ:
218 case VM86_FREE_IRQ:
219 case VM86_GET_IRQ_BITS:
220 case VM86_GET_AND_RESET_IRQ:
221 ret = do_vm86_irq_handling(regs.ebx, (int)regs.ecx);
222 goto out;
223 case VM86_PLUS_INSTALL_CHECK:
224 /* NOTE: on old vm86 stuff this will return the error
e49332bd 225 from access_ok(), because the subfunction is
1da177e4
LT		 226 interpreted as (invalid) address to vm86_struct.
227 So the installation check works.
228 */
229 ret = 0;
230 goto out;
231 }
232
233 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
234 ret = -EPERM;
235 if (tsk->thread.saved_esp0)
236 goto out;
237 v86 = (struct vm86plus_struct __user *)regs.ecx;
238 tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
239 tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
240 (long)&info.regs32 - (long)&info.regs.VM86_REGS_PART2);
241 ret = -EFAULT;
242 if (tmp)
243 goto out;
244 info.regs32 = &regs;
245 info.vm86plus.is_vm86pus = 1;
246 tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
247 do_sys_vm86(&info, tsk);
248 ret = 0; /* we never return here */
249out:
250 return ret;
251}
252
253
254static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
255{
256 struct tss_struct *tss;
257/*
258 * make sure the vm86() system call doesn't try to do anything silly
259 */
260 info->regs.__null_ds = 0;
261 info->regs.__null_es = 0;
262
263/* we are clearing fs,gs later just before "jmp resume_userspace",
264 * because starting with Linux 2.1.x they aren't no longer saved/restored
265 */
266
267/*
268 * The eflags register is also special: we cannot trust that the user
269 * has set it up safely, so this makes sure interrupt etc flags are
270 * inherited from protected mode.
271 */
272 VEFLAGS = info->regs.eflags;
273 info->regs.eflags &= SAFE_MASK;
274 info->regs.eflags |= info->regs32->eflags & ~SAFE_MASK;
275 info->regs.eflags |= VM_MASK;
276
277 switch (info->cpu_type) {
278 case CPU_286:
279 tsk->thread.v86mask = 0;
280 break;
281 case CPU_386:
282 tsk->thread.v86mask = NT_MASK | IOPL_MASK;
283 break;
284 case CPU_486:
285 tsk->thread.v86mask = AC_MASK | NT_MASK | IOPL_MASK;
286 break;
287 default:
288 tsk->thread.v86mask = ID_MASK | AC_MASK | NT_MASK | IOPL_MASK;
289 break;
290 }
291
292/*
293 * Save old state, set default return value (%eax) to 0
294 */
295 info->regs32->eax = 0;
296 tsk->thread.saved_esp0 = tsk->thread.esp0;
4d37e7e3
ZA		 297 savesegment(fs, tsk->thread.saved_fs);
298 savesegment(gs, tsk->thread.saved_gs);
1da177e4
LT		 299
300 tss = &per_cpu(init_tss, get_cpu());
301 tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0;
302 if (cpu_has_sep)
303 tsk->thread.sysenter_cs = 0;
304 load_esp0(tss, &tsk->thread);
305 put_cpu();
306
307 tsk->thread.screen_bitmap = info->screen_bitmap;
308 if (info->flags & VM86_SCREEN_BITMAP)
309 mark_screen_rdonly(tsk);
310 __asm__ __volatile__(
311 "xorl %%eax,%%eax; movl %%eax,%%fs; movl %%eax,%%gs\n\t"
312 "movl %0,%%esp\n\t"
313 "movl %1,%%ebp\n\t"
314 "jmp resume_userspace"
315 : /* no outputs */
316 :"r" (&info->regs), "r" (tsk->thread_info) : "ax");
317 /* we never return here */
318}
319
320static inline void return_to_32bit(struct kernel_vm86_regs * regs16, int retval)
321{
322 struct pt_regs * regs32;
323
324 regs32 = save_v86_state(regs16);
325 regs32->eax = retval;
326 __asm__ __volatile__("movl %0,%%esp\n\t"
327 "movl %1,%%ebp\n\t"
328 "jmp resume_userspace"
329 : : "r" (regs32), "r" (current_thread_info()));
330}
331
332static inline void set_IF(struct kernel_vm86_regs * regs)
333{
334 VEFLAGS |= VIF_MASK;
335 if (VEFLAGS & VIP_MASK)
336 return_to_32bit(regs, VM86_STI);
337}
338
339static inline void clear_IF(struct kernel_vm86_regs * regs)
340{
341 VEFLAGS &= ~VIF_MASK;
342}
343
344static inline void clear_TF(struct kernel_vm86_regs * regs)
345{
346 regs->eflags &= ~TF_MASK;
347}
348
349static inline void clear_AC(struct kernel_vm86_regs * regs)
350{
351 regs->eflags &= ~AC_MASK;
352}
353
354/* It is correct to call set_IF(regs) from the set_vflags_*
355 * functions. However someone forgot to call clear_IF(regs)
356 * in the opposite case.
357 * After the command sequence CLI PUSHF STI POPF you should
358 * end up with interrups disabled, but you ended up with
359 * interrupts enabled.
360 * ( I was testing my own changes, but the only bug I
361 * could find was in a function I had not changed. )
362 * [KD]
363 */
364
365static inline void set_vflags_long(unsigned long eflags, struct kernel_vm86_regs * regs)
366{
367 set_flags(VEFLAGS, eflags, current->thread.v86mask);
368 set_flags(regs->eflags, eflags, SAFE_MASK);
369 if (eflags & IF_MASK)
370 set_IF(regs);
371 else
372 clear_IF(regs);
373}
374
375static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs * regs)
376{
377 set_flags(VFLAGS, flags, current->thread.v86mask);
378 set_flags(regs->eflags, flags, SAFE_MASK);
379 if (flags & IF_MASK)
380 set_IF(regs);
381 else
382 clear_IF(regs);
383}
384
385static inline unsigned long get_vflags(struct kernel_vm86_regs * regs)
386{
387 unsigned long flags = regs->eflags & RETURN_MASK;
388
389 if (VEFLAGS & VIF_MASK)
390 flags |= IF_MASK;
391 flags |= IOPL_MASK;
392 return flags | (VEFLAGS & current->thread.v86mask);
393}
394
395static inline int is_revectored(int nr, struct revectored_struct * bitmap)
396{
397 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
398 :"=r" (nr)
399 :"m" (*bitmap),"r" (nr));
400 return nr;
401}
402
403#define val_byte(val, n) (((__u8 *)&val)[n])
404
405#define pushb(base, ptr, val, err_label) \
406 do { \
407 __u8 __val = val; \
408 ptr--; \
409 if (put_user(__val, base + ptr) < 0) \
410 goto err_label; \
411 } while(0)
412
413#define pushw(base, ptr, val, err_label) \
414 do { \
415 __u16 __val = val; \
416 ptr--; \
417 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
418 goto err_label; \
419 ptr--; \
420 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
421 goto err_label; \
422 } while(0)
423
424#define pushl(base, ptr, val, err_label) \
425 do { \
426 __u32 __val = val; \
427 ptr--; \
428 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
429 goto err_label; \
430 ptr--; \
431 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
432 goto err_label; \
433 ptr--; \
434 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
435 goto err_label; \
436 ptr--; \
437 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
438 goto err_label; \
439 } while(0)
440
441#define popb(base, ptr, err_label) \
442 ({ \
443 __u8 __res; \
444 if (get_user(__res, base + ptr) < 0) \
445 goto err_label; \
446 ptr++; \
447 __res; \
448 })
449
450#define popw(base, ptr, err_label) \
451 ({ \
452 __u16 __res; \
453 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
454 goto err_label; \
455 ptr++; \
456 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
457 goto err_label; \
458 ptr++; \
459 __res; \
460 })
461
462#define popl(base, ptr, err_label) \
463 ({ \
464 __u32 __res; \
465 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
466 goto err_label; \
467 ptr++; \
468 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
469 goto err_label; \
470 ptr++; \
471 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
472 goto err_label; \
473 ptr++; \
474 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
475 goto err_label; \
476 ptr++; \
477 __res; \
478 })
479
480/* There are so many possible reasons for this function to return
481 * VM86_INTx, so adding another doesn't bother me. We can expect
482 * userspace programs to be able to handle it. (Getting a problem
483 * in userspace is always better than an Oops anyway.) [KD]
484 */
485static void do_int(struct kernel_vm86_regs *regs, int i,
486 unsigned char __user * ssp, unsigned short sp)
487{
488 unsigned long __user *intr_ptr;
489 unsigned long segoffs;
490
491 if (regs->cs == BIOSSEG)
492 goto cannot_handle;
493 if (is_revectored(i, &KVM86->int_revectored))
494 goto cannot_handle;
495 if (i==0x21 && is_revectored(AH(regs),&KVM86->int21_revectored))
496 goto cannot_handle;
497 intr_ptr = (unsigned long __user *) (i << 2);
498 if (get_user(segoffs, intr_ptr))
499 goto cannot_handle;
500 if ((segoffs >> 16) == BIOSSEG)
501 goto cannot_handle;
502 pushw(ssp, sp, get_vflags(regs), cannot_handle);
503 pushw(ssp, sp, regs->cs, cannot_handle);
504 pushw(ssp, sp, IP(regs), cannot_handle);
505 regs->cs = segoffs >> 16;
506 SP(regs) -= 6;
507 IP(regs) = segoffs & 0xffff;
508 clear_TF(regs);
509 clear_IF(regs);
510 clear_AC(regs);
511 return;
512
513cannot_handle:
514 return_to_32bit(regs, VM86_INTx + (i << 8));
515}
516
517int handle_vm86_trap(struct kernel_vm86_regs * regs, long error_code, int trapno)
518{
519 if (VMPI.is_vm86pus) {
520 if ( (trapno==3) || (trapno==1) )
521 return_to_32bit(regs, VM86_TRAP + (trapno << 8));
522 do_int(regs, trapno, (unsigned char __user *) (regs->ss << 4), SP(regs));
523 return 0;
524 }
525 if (trapno !=1)
526 return 1; /* we let this handle by the calling routine */
527 if (current->ptrace & PT_PTRACED) {
528 unsigned long flags;
529 spin_lock_irqsave(&current->sighand->siglock, flags);
530 sigdelset(&current->blocked, SIGTRAP);
531 recalc_sigpending();
532 spin_unlock_irqrestore(&current->sighand->siglock, flags);
533 }
534 send_sig(SIGTRAP, current, 1);
535 current->thread.trap_no = trapno;
536 current->thread.error_code = error_code;
537 return 0;
538}
539
540void handle_vm86_fault(struct kernel_vm86_regs * regs, long error_code)
541{
542 unsigned char opcode;
543 unsigned char __user *csp;
544 unsigned char __user *ssp;
5fd75ebb 545 unsigned short ip, sp, orig_flags;
1da177e4
LT		 546 int data32, pref_done;
547
548#define CHECK_IF_IN_TRAP \
549 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
550 newflags |= TF_MASK
551#define VM86_FAULT_RETURN do { \
552 if (VMPI.force_return_for_pic && (VEFLAGS & (IF_MASK | VIF_MASK))) \
553 return_to_32bit(regs, VM86_PICRETURN); \
5fd75ebb
PT		 554 if (orig_flags & TF_MASK) \
555 handle_vm86_trap(regs, 0, 1); \
1da177e4
LT		 556 return; } while (0)
557
5fd75ebb
PT		 558 orig_flags = *(unsigned short *)&regs->eflags;
559
1da177e4
LT		 560 csp = (unsigned char __user *) (regs->cs << 4);
561 ssp = (unsigned char __user *) (regs->ss << 4);
562 sp = SP(regs);
563 ip = IP(regs);
564
565 data32 = 0;
566 pref_done = 0;
567 do {
568 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
569 case 0x66: /* 32-bit data */ data32=1; break;
570 case 0x67: /* 32-bit address */ break;
571 case 0x2e: /* CS */ break;
572 case 0x3e: /* DS */ break;
573 case 0x26: /* ES */ break;
574 case 0x36: /* SS */ break;
575 case 0x65: /* GS */ break;
576 case 0x64: /* FS */ break;
577 case 0xf2: /* repnz */ break;
578 case 0xf3: /* rep */ break;
579 default: pref_done = 1;
580 }
581 } while (!pref_done);
582
583 switch (opcode) {
584
585 /* pushf */
586 case 0x9c:
587 if (data32) {
588 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
589 SP(regs) -= 4;
590 } else {
591 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
592 SP(regs) -= 2;
593 }
594 IP(regs) = ip;
595 VM86_FAULT_RETURN;
596
597 /* popf */
598 case 0x9d:
599 {
600 unsigned long newflags;
601 if (data32) {
602 newflags=popl(ssp, sp, simulate_sigsegv);
603 SP(regs) += 4;
604 } else {
605 newflags = popw(ssp, sp, simulate_sigsegv);
606 SP(regs) += 2;
607 }
608 IP(regs) = ip;
609 CHECK_IF_IN_TRAP;
610 if (data32) {
611 set_vflags_long(newflags, regs);
612 } else {
613 set_vflags_short(newflags, regs);
614 }
615 VM86_FAULT_RETURN;
616 }
617
618 /* int xx */
619 case 0xcd: {
620 int intno=popb(csp, ip, simulate_sigsegv);
621 IP(regs) = ip;
622 if (VMPI.vm86dbg_active) {
623 if ( (1 << (intno &7)) & VMPI.vm86dbg_intxxtab[intno >> 3] )
624 return_to_32bit(regs, VM86_INTx + (intno << 8));
625 }
626 do_int(regs, intno, ssp, sp);
627 return;
628 }
629
630 /* iret */
631 case 0xcf:
632 {
633 unsigned long newip;
634 unsigned long newcs;
635 unsigned long newflags;
636 if (data32) {
637 newip=popl(ssp, sp, simulate_sigsegv);
638 newcs=popl(ssp, sp, simulate_sigsegv);
639 newflags=popl(ssp, sp, simulate_sigsegv);
640 SP(regs) += 12;
641 } else {
642 newip = popw(ssp, sp, simulate_sigsegv);
643 newcs = popw(ssp, sp, simulate_sigsegv);
644 newflags = popw(ssp, sp, simulate_sigsegv);
645 SP(regs) += 6;
646 }
647 IP(regs) = newip;
648 regs->cs = newcs;
649 CHECK_IF_IN_TRAP;
650 if (data32) {
651 set_vflags_long(newflags, regs);
652 } else {
653 set_vflags_short(newflags, regs);
654 }
655 VM86_FAULT_RETURN;
656 }
657
658 /* cli */
659 case 0xfa:
660 IP(regs) = ip;
661 clear_IF(regs);
662 VM86_FAULT_RETURN;
663
664 /* sti */
665 /*
666 * Damn. This is incorrect: the 'sti' instruction should actually
667 * enable interrupts after the /next/ instruction. Not good.
668 *
669 * Probably needs some horsing around with the TF flag. Aiee..
670 */
671 case 0xfb:
672 IP(regs) = ip;
673 set_IF(regs);
674 VM86_FAULT_RETURN;
675
676 default:
677 return_to_32bit(regs, VM86_UNKNOWN);
678 }
679
680 return;
681
682simulate_sigsegv:
683 /* FIXME: After a long discussion with Stas we finally
684 * agreed, that this is wrong. Here we should
685 * really send a SIGSEGV to the user program.
686 * But how do we create the correct context? We
687 * are inside a general protection fault handler
688 * and has just returned from a page fault handler.
689 * The correct context for the signal handler
690 * should be a mixture of the two, but how do we
691 * get the information? [KD]
692 */
693 return_to_32bit(regs, VM86_UNKNOWN);
694}
695
696/* ---------------- vm86 special IRQ passing stuff ----------------- */
697
698#define VM86_IRQNAME "vm86irq"
699
700static struct vm86_irqs {
701 struct task_struct *tsk;
702 int sig;
703} vm86_irqs[16];
704
705static DEFINE_SPINLOCK(irqbits_lock);
706static int irqbits;
707
708#define ALLOWED_SIGS ( 1 /* 0 = don't send a signal */ \
709 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
710 | (1 << SIGUNUSED) )
711
712static irqreturn_t irq_handler(int intno, void *dev_id, struct pt_regs * regs)
713{
714 int irq_bit;
715 unsigned long flags;
716
717 spin_lock_irqsave(&irqbits_lock, flags);
718 irq_bit = 1 << intno;
719 if ((irqbits & irq_bit) || ! vm86_irqs[intno].tsk)
720 goto out;
721 irqbits |= irq_bit;
722 if (vm86_irqs[intno].sig)
723 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
1da177e4
LT		 724 /*
725 * IRQ will be re-enabled when user asks for the irq (whether
726 * polling or as a result of the signal)
727 */
ad671423
PP		 728 disable_irq_nosync(intno);
729 spin_unlock_irqrestore(&irqbits_lock, flags);
1da177e4
LT		 730 return IRQ_HANDLED;
731
732out:
733 spin_unlock_irqrestore(&irqbits_lock, flags);
734 return IRQ_NONE;
735}
736
737static inline void free_vm86_irq(int irqnumber)
738{
739 unsigned long flags;
740
741 free_irq(irqnumber, NULL);
742 vm86_irqs[irqnumber].tsk = NULL;
743
744 spin_lock_irqsave(&irqbits_lock, flags);
745 irqbits &= ~(1 << irqnumber);
746 spin_unlock_irqrestore(&irqbits_lock, flags);
747}
748
749void release_vm86_irqs(struct task_struct *task)
750{
751 int i;
752 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
753 if (vm86_irqs[i].tsk == task)
754 free_vm86_irq(i);
755}
756
757static inline int get_and_reset_irq(int irqnumber)
758{
759 int bit;
760 unsigned long flags;
ad671423 761 int ret = 0;
1da177e4
LT		 762
763 if (invalid_vm86_irq(irqnumber)) return 0;
764 if (vm86_irqs[irqnumber].tsk != current) return 0;
765 spin_lock_irqsave(&irqbits_lock, flags);
766 bit = irqbits & (1 << irqnumber);
767 irqbits &= ~bit;
ad671423
PP		 768 if (bit) {
769 enable_irq(irqnumber);
770 ret = 1;
771 }
772
1da177e4 773 spin_unlock_irqrestore(&irqbits_lock, flags);
ad671423 774 return ret;
1da177e4
LT		 775}
776
777
778static int do_vm86_irq_handling(int subfunction, int irqnumber)
779{
780 int ret;
781 switch (subfunction) {
782 case VM86_GET_AND_RESET_IRQ: {
783 return get_and_reset_irq(irqnumber);
784 }
785 case VM86_GET_IRQ_BITS: {
786 return irqbits;
787 }
788 case VM86_REQUEST_IRQ: {
789 int sig = irqnumber >> 8;
790 int irq = irqnumber & 255;
791 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
792 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
793 if (invalid_vm86_irq(irq)) return -EPERM;
794 if (vm86_irqs[irq].tsk) return -EPERM;
795 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL);
796 if (ret) return ret;
797 vm86_irqs[irq].sig = sig;
798 vm86_irqs[irq].tsk = current;
799 return irq;
800 }
801 case VM86_FREE_IRQ: {
802 if (invalid_vm86_irq(irqnumber)) return -EPERM;
803 if (!vm86_irqs[irqnumber].tsk) return 0;
804 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
805 free_vm86_irq(irqnumber);
806 return 0;
807 }
808 }
809 return -EINVAL;
810}
811
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