blob: aee14fafd13dfc0f9aa302d9f8d642208f6f4b98 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Christian Kujau624dffc2006-01-15 02:43:54 +01007 * stack - Manfred Spraul <manfred@colorfullife.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 *
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
Randy Dunlapa9415642006-01-11 12:17:48 -080033#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <linux/config.h>
35#include <linux/errno.h>
36#include <linux/interrupt.h>
37#include <linux/sched.h>
38#include <linux/kernel.h>
39#include <linux/signal.h>
40#include <linux/string.h>
41#include <linux/mm.h>
42#include <linux/smp.h>
43#include <linux/smp_lock.h>
44#include <linux/highmem.h>
45#include <linux/ptrace.h>
Jason Baron7e7f8a02006-01-31 16:56:28 -050046#include <linux/audit.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48#include <asm/uaccess.h>
49#include <asm/io.h>
50#include <asm/tlbflush.h>
51#include <asm/irq.h>
52
53/*
54 * Known problems:
55 *
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.
64 *
65 * Let's hope these problems do not actually matter for anything.
66 */
67
68
69#define KVM86 ((struct kernel_vm86_struct *)regs)
70#define VMPI KVM86->vm86plus
71
72
73/*
74 * 8- and 16-bit register defines..
75 */
76#define AL(regs) (((unsigned char *)&((regs)->eax))[0])
77#define AH(regs) (((unsigned char *)&((regs)->eax))[1])
78#define IP(regs) (*(unsigned short *)&((regs)->eip))
79#define SP(regs) (*(unsigned short *)&((regs)->esp))
80
81/*
82 * virtual flags (16 and 32-bit versions)
83 */
84#define VFLAGS (*(unsigned short *)&(current->thread.v86flags))
85#define VEFLAGS (current->thread.v86flags)
86
87#define set_flags(X,new,mask) \
88((X) = ((X) & ~(mask)) | ((new) & (mask)))
89
90#define SAFE_MASK (0xDD5)
91#define RETURN_MASK (0xDFF)
92
93#define VM86_REGS_PART2 orig_eax
94#define VM86_REGS_SIZE1 \
95 ( (unsigned)( & (((struct kernel_vm86_regs *)0)->VM86_REGS_PART2) ) )
96#define VM86_REGS_SIZE2 (sizeof(struct kernel_vm86_regs) - VM86_REGS_SIZE1)
97
98struct pt_regs * FASTCALL(save_v86_state(struct kernel_vm86_regs * regs));
99struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs)
100{
101 struct tss_struct *tss;
102 struct pt_regs *ret;
103 unsigned long tmp;
104
105 /*
106 * This gets called from entry.S with interrupts disabled, but
107 * from process context. Enable interrupts here, before trying
108 * to access user space.
109 */
110 local_irq_enable();
111
112 if (!current->thread.vm86_info) {
113 printk("no vm86_info: BAD\n");
114 do_exit(SIGSEGV);
115 }
116 set_flags(regs->eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);
117 tmp = copy_to_user(&current->thread.vm86_info->regs,regs, VM86_REGS_SIZE1);
118 tmp += copy_to_user(&current->thread.vm86_info->regs.VM86_REGS_PART2,
119 &regs->VM86_REGS_PART2, VM86_REGS_SIZE2);
120 tmp += put_user(current->thread.screen_bitmap,&current->thread.vm86_info->screen_bitmap);
121 if (tmp) {
122 printk("vm86: could not access userspace vm86_info\n");
123 do_exit(SIGSEGV);
124 }
125
126 tss = &per_cpu(init_tss, get_cpu());
127 current->thread.esp0 = current->thread.saved_esp0;
128 current->thread.sysenter_cs = __KERNEL_CS;
129 load_esp0(tss, &current->thread);
130 current->thread.saved_esp0 = 0;
131 put_cpu();
132
133 loadsegment(fs, current->thread.saved_fs);
134 loadsegment(gs, current->thread.saved_gs);
135 ret = KVM86->regs32;
136 return ret;
137}
138
Hugh Dickins60ec5582005-10-29 18:16:34 -0700139static void mark_screen_rdonly(struct mm_struct *mm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140{
141 pgd_t *pgd;
142 pud_t *pud;
143 pmd_t *pmd;
Hugh Dickins60ec5582005-10-29 18:16:34 -0700144 pte_t *pte;
145 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 int i;
147
Hugh Dickins60ec5582005-10-29 18:16:34 -0700148 pgd = pgd_offset(mm, 0xA0000);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 if (pgd_none_or_clear_bad(pgd))
150 goto out;
151 pud = pud_offset(pgd, 0xA0000);
152 if (pud_none_or_clear_bad(pud))
153 goto out;
154 pmd = pmd_offset(pud, 0xA0000);
155 if (pmd_none_or_clear_bad(pmd))
156 goto out;
Hugh Dickins60ec5582005-10-29 18:16:34 -0700157 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 for (i = 0; i < 32; i++) {
159 if (pte_present(*pte))
160 set_pte(pte, pte_wrprotect(*pte));
161 pte++;
162 }
Hugh Dickins60ec5582005-10-29 18:16:34 -0700163 pte_unmap_unlock(pte, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 flush_tlb();
166}
167
168
169
170static int do_vm86_irq_handling(int subfunction, int irqnumber);
171static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
172
173asmlinkage int sys_vm86old(struct pt_regs regs)
174{
175 struct vm86_struct __user *v86 = (struct vm86_struct __user *)regs.ebx;
176 struct kernel_vm86_struct info; /* declare this _on top_,
177 * this avoids wasting of stack space.
178 * This remains on the stack until we
179 * return to 32 bit user space.
180 */
181 struct task_struct *tsk;
182 int tmp, ret = -EPERM;
183
184 tsk = current;
185 if (tsk->thread.saved_esp0)
186 goto out;
187 tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
188 tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
189 (long)&info.vm86plus - (long)&info.regs.VM86_REGS_PART2);
190 ret = -EFAULT;
191 if (tmp)
192 goto out;
193 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
194 info.regs32 = &regs;
195 tsk->thread.vm86_info = v86;
196 do_sys_vm86(&info, tsk);
197 ret = 0; /* we never return here */
198out:
199 return ret;
200}
201
202
203asmlinkage int sys_vm86(struct pt_regs regs)
204{
205 struct kernel_vm86_struct info; /* declare this _on top_,
206 * this avoids wasting of stack space.
207 * This remains on the stack until we
208 * return to 32 bit user space.
209 */
210 struct task_struct *tsk;
211 int tmp, ret;
212 struct vm86plus_struct __user *v86;
213
214 tsk = current;
215 switch (regs.ebx) {
216 case VM86_REQUEST_IRQ:
217 case VM86_FREE_IRQ:
218 case VM86_GET_IRQ_BITS:
219 case VM86_GET_AND_RESET_IRQ:
220 ret = do_vm86_irq_handling(regs.ebx, (int)regs.ecx);
221 goto out;
222 case VM86_PLUS_INSTALL_CHECK:
223 /* NOTE: on old vm86 stuff this will return the error
Jesper Juhle49332b2005-05-01 08:59:08 -0700224 from access_ok(), because the subfunction is
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 interpreted as (invalid) address to vm86_struct.
226 So the installation check works.
227 */
228 ret = 0;
229 goto out;
230 }
231
232 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
233 ret = -EPERM;
234 if (tsk->thread.saved_esp0)
235 goto out;
236 v86 = (struct vm86plus_struct __user *)regs.ecx;
237 tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
238 tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
239 (long)&info.regs32 - (long)&info.regs.VM86_REGS_PART2);
240 ret = -EFAULT;
241 if (tmp)
242 goto out;
243 info.regs32 = &regs;
244 info.vm86plus.is_vm86pus = 1;
245 tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
246 do_sys_vm86(&info, tsk);
247 ret = 0; /* we never return here */
248out:
249 return ret;
250}
251
252
253static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
254{
255 struct tss_struct *tss;
Jason Baron7e7f8a02006-01-31 16:56:28 -0500256 long eax;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257/*
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;
Zachary Amsden4d37e7e2005-09-03 15:56:38 -0700297 savesegment(fs, tsk->thread.saved_fs);
298 savesegment(gs, tsk->thread.saved_gs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299
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)
Hugh Dickins60ec5582005-10-29 18:16:34 -0700309 mark_screen_rdonly(tsk->mm);
Jason Baron7e7f8a02006-01-31 16:56:28 -0500310 __asm__ __volatile__("xorl %eax,%eax; movl %eax,%fs; movl %eax,%gs\n\t");
311 __asm__ __volatile__("movl %%eax, %0\n" :"=r"(eax));
312
313 /*call audit_syscall_exit since we do not exit via the normal paths */
314 if (unlikely(current->audit_context))
315 audit_syscall_exit(current, AUDITSC_RESULT(eax), eax);
316
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 __asm__ __volatile__(
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 "movl %0,%%esp\n\t"
319 "movl %1,%%ebp\n\t"
320 "jmp resume_userspace"
321 : /* no outputs */
Jason Baron7e7f8a02006-01-31 16:56:28 -0500322 :"r" (&info->regs), "r" (task_thread_info(tsk)));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 /* we never return here */
324}
325
326static inline void return_to_32bit(struct kernel_vm86_regs * regs16, int retval)
327{
328 struct pt_regs * regs32;
329
330 regs32 = save_v86_state(regs16);
331 regs32->eax = retval;
332 __asm__ __volatile__("movl %0,%%esp\n\t"
333 "movl %1,%%ebp\n\t"
334 "jmp resume_userspace"
335 : : "r" (regs32), "r" (current_thread_info()));
336}
337
338static inline void set_IF(struct kernel_vm86_regs * regs)
339{
340 VEFLAGS |= VIF_MASK;
341 if (VEFLAGS & VIP_MASK)
342 return_to_32bit(regs, VM86_STI);
343}
344
345static inline void clear_IF(struct kernel_vm86_regs * regs)
346{
347 VEFLAGS &= ~VIF_MASK;
348}
349
350static inline void clear_TF(struct kernel_vm86_regs * regs)
351{
352 regs->eflags &= ~TF_MASK;
353}
354
355static inline void clear_AC(struct kernel_vm86_regs * regs)
356{
357 regs->eflags &= ~AC_MASK;
358}
359
360/* It is correct to call set_IF(regs) from the set_vflags_*
361 * functions. However someone forgot to call clear_IF(regs)
362 * in the opposite case.
363 * After the command sequence CLI PUSHF STI POPF you should
364 * end up with interrups disabled, but you ended up with
365 * interrupts enabled.
366 * ( I was testing my own changes, but the only bug I
367 * could find was in a function I had not changed. )
368 * [KD]
369 */
370
371static inline void set_vflags_long(unsigned long eflags, struct kernel_vm86_regs * regs)
372{
373 set_flags(VEFLAGS, eflags, current->thread.v86mask);
374 set_flags(regs->eflags, eflags, SAFE_MASK);
375 if (eflags & IF_MASK)
376 set_IF(regs);
377 else
378 clear_IF(regs);
379}
380
381static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs * regs)
382{
383 set_flags(VFLAGS, flags, current->thread.v86mask);
384 set_flags(regs->eflags, flags, SAFE_MASK);
385 if (flags & IF_MASK)
386 set_IF(regs);
387 else
388 clear_IF(regs);
389}
390
391static inline unsigned long get_vflags(struct kernel_vm86_regs * regs)
392{
393 unsigned long flags = regs->eflags & RETURN_MASK;
394
395 if (VEFLAGS & VIF_MASK)
396 flags |= IF_MASK;
397 flags |= IOPL_MASK;
398 return flags | (VEFLAGS & current->thread.v86mask);
399}
400
401static inline int is_revectored(int nr, struct revectored_struct * bitmap)
402{
403 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
404 :"=r" (nr)
405 :"m" (*bitmap),"r" (nr));
406 return nr;
407}
408
409#define val_byte(val, n) (((__u8 *)&val)[n])
410
411#define pushb(base, ptr, val, err_label) \
412 do { \
413 __u8 __val = val; \
414 ptr--; \
415 if (put_user(__val, base + ptr) < 0) \
416 goto err_label; \
417 } while(0)
418
419#define pushw(base, ptr, val, err_label) \
420 do { \
421 __u16 __val = val; \
422 ptr--; \
423 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
424 goto err_label; \
425 ptr--; \
426 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
427 goto err_label; \
428 } while(0)
429
430#define pushl(base, ptr, val, err_label) \
431 do { \
432 __u32 __val = val; \
433 ptr--; \
434 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
435 goto err_label; \
436 ptr--; \
437 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
438 goto err_label; \
439 ptr--; \
440 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
441 goto err_label; \
442 ptr--; \
443 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
444 goto err_label; \
445 } while(0)
446
447#define popb(base, ptr, err_label) \
448 ({ \
449 __u8 __res; \
450 if (get_user(__res, base + ptr) < 0) \
451 goto err_label; \
452 ptr++; \
453 __res; \
454 })
455
456#define popw(base, ptr, err_label) \
457 ({ \
458 __u16 __res; \
459 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
460 goto err_label; \
461 ptr++; \
462 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
463 goto err_label; \
464 ptr++; \
465 __res; \
466 })
467
468#define popl(base, ptr, err_label) \
469 ({ \
470 __u32 __res; \
471 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
472 goto err_label; \
473 ptr++; \
474 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
475 goto err_label; \
476 ptr++; \
477 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
478 goto err_label; \
479 ptr++; \
480 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
481 goto err_label; \
482 ptr++; \
483 __res; \
484 })
485
486/* There are so many possible reasons for this function to return
487 * VM86_INTx, so adding another doesn't bother me. We can expect
488 * userspace programs to be able to handle it. (Getting a problem
489 * in userspace is always better than an Oops anyway.) [KD]
490 */
491static void do_int(struct kernel_vm86_regs *regs, int i,
492 unsigned char __user * ssp, unsigned short sp)
493{
494 unsigned long __user *intr_ptr;
495 unsigned long segoffs;
496
497 if (regs->cs == BIOSSEG)
498 goto cannot_handle;
499 if (is_revectored(i, &KVM86->int_revectored))
500 goto cannot_handle;
501 if (i==0x21 && is_revectored(AH(regs),&KVM86->int21_revectored))
502 goto cannot_handle;
503 intr_ptr = (unsigned long __user *) (i << 2);
504 if (get_user(segoffs, intr_ptr))
505 goto cannot_handle;
506 if ((segoffs >> 16) == BIOSSEG)
507 goto cannot_handle;
508 pushw(ssp, sp, get_vflags(regs), cannot_handle);
509 pushw(ssp, sp, regs->cs, cannot_handle);
510 pushw(ssp, sp, IP(regs), cannot_handle);
511 regs->cs = segoffs >> 16;
512 SP(regs) -= 6;
513 IP(regs) = segoffs & 0xffff;
514 clear_TF(regs);
515 clear_IF(regs);
516 clear_AC(regs);
517 return;
518
519cannot_handle:
520 return_to_32bit(regs, VM86_INTx + (i << 8));
521}
522
523int handle_vm86_trap(struct kernel_vm86_regs * regs, long error_code, int trapno)
524{
525 if (VMPI.is_vm86pus) {
526 if ( (trapno==3) || (trapno==1) )
527 return_to_32bit(regs, VM86_TRAP + (trapno << 8));
528 do_int(regs, trapno, (unsigned char __user *) (regs->ss << 4), SP(regs));
529 return 0;
530 }
531 if (trapno !=1)
532 return 1; /* we let this handle by the calling routine */
533 if (current->ptrace & PT_PTRACED) {
534 unsigned long flags;
535 spin_lock_irqsave(&current->sighand->siglock, flags);
536 sigdelset(&current->blocked, SIGTRAP);
537 recalc_sigpending();
538 spin_unlock_irqrestore(&current->sighand->siglock, flags);
539 }
540 send_sig(SIGTRAP, current, 1);
541 current->thread.trap_no = trapno;
542 current->thread.error_code = error_code;
543 return 0;
544}
545
546void handle_vm86_fault(struct kernel_vm86_regs * regs, long error_code)
547{
548 unsigned char opcode;
549 unsigned char __user *csp;
550 unsigned char __user *ssp;
Petr Tesarik5fd75eb2005-09-03 15:56:28 -0700551 unsigned short ip, sp, orig_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 int data32, pref_done;
553
554#define CHECK_IF_IN_TRAP \
555 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
556 newflags |= TF_MASK
557#define VM86_FAULT_RETURN do { \
558 if (VMPI.force_return_for_pic && (VEFLAGS & (IF_MASK | VIF_MASK))) \
559 return_to_32bit(regs, VM86_PICRETURN); \
Petr Tesarik5fd75eb2005-09-03 15:56:28 -0700560 if (orig_flags & TF_MASK) \
561 handle_vm86_trap(regs, 0, 1); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 return; } while (0)
563
Petr Tesarik5fd75eb2005-09-03 15:56:28 -0700564 orig_flags = *(unsigned short *)&regs->eflags;
565
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 csp = (unsigned char __user *) (regs->cs << 4);
567 ssp = (unsigned char __user *) (regs->ss << 4);
568 sp = SP(regs);
569 ip = IP(regs);
570
571 data32 = 0;
572 pref_done = 0;
573 do {
574 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
575 case 0x66: /* 32-bit data */ data32=1; break;
576 case 0x67: /* 32-bit address */ break;
577 case 0x2e: /* CS */ break;
578 case 0x3e: /* DS */ break;
579 case 0x26: /* ES */ break;
580 case 0x36: /* SS */ break;
581 case 0x65: /* GS */ break;
582 case 0x64: /* FS */ break;
583 case 0xf2: /* repnz */ break;
584 case 0xf3: /* rep */ break;
585 default: pref_done = 1;
586 }
587 } while (!pref_done);
588
589 switch (opcode) {
590
591 /* pushf */
592 case 0x9c:
593 if (data32) {
594 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
595 SP(regs) -= 4;
596 } else {
597 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
598 SP(regs) -= 2;
599 }
600 IP(regs) = ip;
601 VM86_FAULT_RETURN;
602
603 /* popf */
604 case 0x9d:
605 {
606 unsigned long newflags;
607 if (data32) {
608 newflags=popl(ssp, sp, simulate_sigsegv);
609 SP(regs) += 4;
610 } else {
611 newflags = popw(ssp, sp, simulate_sigsegv);
612 SP(regs) += 2;
613 }
614 IP(regs) = ip;
615 CHECK_IF_IN_TRAP;
616 if (data32) {
617 set_vflags_long(newflags, regs);
618 } else {
619 set_vflags_short(newflags, regs);
620 }
621 VM86_FAULT_RETURN;
622 }
623
624 /* int xx */
625 case 0xcd: {
626 int intno=popb(csp, ip, simulate_sigsegv);
627 IP(regs) = ip;
628 if (VMPI.vm86dbg_active) {
629 if ( (1 << (intno &7)) & VMPI.vm86dbg_intxxtab[intno >> 3] )
630 return_to_32bit(regs, VM86_INTx + (intno << 8));
631 }
632 do_int(regs, intno, ssp, sp);
633 return;
634 }
635
636 /* iret */
637 case 0xcf:
638 {
639 unsigned long newip;
640 unsigned long newcs;
641 unsigned long newflags;
642 if (data32) {
643 newip=popl(ssp, sp, simulate_sigsegv);
644 newcs=popl(ssp, sp, simulate_sigsegv);
645 newflags=popl(ssp, sp, simulate_sigsegv);
646 SP(regs) += 12;
647 } else {
648 newip = popw(ssp, sp, simulate_sigsegv);
649 newcs = popw(ssp, sp, simulate_sigsegv);
650 newflags = popw(ssp, sp, simulate_sigsegv);
651 SP(regs) += 6;
652 }
653 IP(regs) = newip;
654 regs->cs = newcs;
655 CHECK_IF_IN_TRAP;
656 if (data32) {
657 set_vflags_long(newflags, regs);
658 } else {
659 set_vflags_short(newflags, regs);
660 }
661 VM86_FAULT_RETURN;
662 }
663
664 /* cli */
665 case 0xfa:
666 IP(regs) = ip;
667 clear_IF(regs);
668 VM86_FAULT_RETURN;
669
670 /* sti */
671 /*
672 * Damn. This is incorrect: the 'sti' instruction should actually
673 * enable interrupts after the /next/ instruction. Not good.
674 *
675 * Probably needs some horsing around with the TF flag. Aiee..
676 */
677 case 0xfb:
678 IP(regs) = ip;
679 set_IF(regs);
680 VM86_FAULT_RETURN;
681
682 default:
683 return_to_32bit(regs, VM86_UNKNOWN);
684 }
685
686 return;
687
688simulate_sigsegv:
689 /* FIXME: After a long discussion with Stas we finally
690 * agreed, that this is wrong. Here we should
691 * really send a SIGSEGV to the user program.
692 * But how do we create the correct context? We
693 * are inside a general protection fault handler
694 * and has just returned from a page fault handler.
695 * The correct context for the signal handler
696 * should be a mixture of the two, but how do we
697 * get the information? [KD]
698 */
699 return_to_32bit(regs, VM86_UNKNOWN);
700}
701
702/* ---------------- vm86 special IRQ passing stuff ----------------- */
703
704#define VM86_IRQNAME "vm86irq"
705
706static struct vm86_irqs {
707 struct task_struct *tsk;
708 int sig;
709} vm86_irqs[16];
710
711static DEFINE_SPINLOCK(irqbits_lock);
712static int irqbits;
713
714#define ALLOWED_SIGS ( 1 /* 0 = don't send a signal */ \
715 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
716 | (1 << SIGUNUSED) )
717
718static irqreturn_t irq_handler(int intno, void *dev_id, struct pt_regs * regs)
719{
720 int irq_bit;
721 unsigned long flags;
722
723 spin_lock_irqsave(&irqbits_lock, flags);
724 irq_bit = 1 << intno;
725 if ((irqbits & irq_bit) || ! vm86_irqs[intno].tsk)
726 goto out;
727 irqbits |= irq_bit;
728 if (vm86_irqs[intno].sig)
729 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 /*
731 * IRQ will be re-enabled when user asks for the irq (whether
732 * polling or as a result of the signal)
733 */
Pavel Pisaad671422005-05-01 08:58:52 -0700734 disable_irq_nosync(intno);
735 spin_unlock_irqrestore(&irqbits_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 return IRQ_HANDLED;
737
738out:
739 spin_unlock_irqrestore(&irqbits_lock, flags);
740 return IRQ_NONE;
741}
742
743static inline void free_vm86_irq(int irqnumber)
744{
745 unsigned long flags;
746
747 free_irq(irqnumber, NULL);
748 vm86_irqs[irqnumber].tsk = NULL;
749
750 spin_lock_irqsave(&irqbits_lock, flags);
751 irqbits &= ~(1 << irqnumber);
752 spin_unlock_irqrestore(&irqbits_lock, flags);
753}
754
755void release_vm86_irqs(struct task_struct *task)
756{
757 int i;
758 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
759 if (vm86_irqs[i].tsk == task)
760 free_vm86_irq(i);
761}
762
763static inline int get_and_reset_irq(int irqnumber)
764{
765 int bit;
766 unsigned long flags;
Pavel Pisaad671422005-05-01 08:58:52 -0700767 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768
769 if (invalid_vm86_irq(irqnumber)) return 0;
770 if (vm86_irqs[irqnumber].tsk != current) return 0;
771 spin_lock_irqsave(&irqbits_lock, flags);
772 bit = irqbits & (1 << irqnumber);
773 irqbits &= ~bit;
Pavel Pisaad671422005-05-01 08:58:52 -0700774 if (bit) {
775 enable_irq(irqnumber);
776 ret = 1;
777 }
778
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 spin_unlock_irqrestore(&irqbits_lock, flags);
Pavel Pisaad671422005-05-01 08:58:52 -0700780 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781}
782
783
784static int do_vm86_irq_handling(int subfunction, int irqnumber)
785{
786 int ret;
787 switch (subfunction) {
788 case VM86_GET_AND_RESET_IRQ: {
789 return get_and_reset_irq(irqnumber);
790 }
791 case VM86_GET_IRQ_BITS: {
792 return irqbits;
793 }
794 case VM86_REQUEST_IRQ: {
795 int sig = irqnumber >> 8;
796 int irq = irqnumber & 255;
797 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
798 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
799 if (invalid_vm86_irq(irq)) return -EPERM;
800 if (vm86_irqs[irq].tsk) return -EPERM;
801 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL);
802 if (ret) return ret;
803 vm86_irqs[irq].sig = sig;
804 vm86_irqs[irq].tsk = current;
805 return irq;
806 }
807 case VM86_FREE_IRQ: {
808 if (invalid_vm86_irq(irqnumber)) return -EPERM;
809 if (!vm86_irqs[irqnumber].tsk) return 0;
810 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
811 free_vm86_irq(irqnumber);
812 return 0;
813 }
814 }
815 return -EINVAL;
816}
817