1 /*
2 * Copyright (C) 1994 Linus Torvalds
3 *
4 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
5 * stack - Manfred Spraul <manfred@colorfullife.com>
6 *
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>
11 *
12 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
13 * <kasperd@daimi.au.dk>
14 *
15 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
16 * caused by Kasper Dupont's changes - Stas Sergeev
17 *
18 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
19 * Kasper Dupont <kasperd@daimi.au.dk>
20 *
21 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
22 * Kasper Dupont <kasperd@daimi.au.dk>
23 *
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>
28 *
29 */
30
31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
32
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/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/highmem.h>
44 #include <linux/ptrace.h>
45 #include <linux/audit.h>
46 #include <linux/stddef.h>
47
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)->pt.ax))[0])
77 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1])
78 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip))
79 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp))
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 /* convert kernel_vm86_regs to vm86_regs */
copy_vm86_regs_to_user(struct vm86_regs __user * user,const struct kernel_vm86_regs * regs)94 static int copy_vm86_regs_to_user(struct vm86_regs __user *user,
95 const struct kernel_vm86_regs *regs)
96 {
97 int ret = 0;
98
99 /*
100 * kernel_vm86_regs is missing gs, so copy everything up to
101 * (but not including) orig_eax, and then rest including orig_eax.
102 */
103 ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.orig_ax));
104 ret += copy_to_user(&user->orig_eax, ®s->pt.orig_ax,
105 sizeof(struct kernel_vm86_regs) -
106 offsetof(struct kernel_vm86_regs, pt.orig_ax));
107
108 return ret;
109 }
110
111 /* convert vm86_regs to kernel_vm86_regs */
copy_vm86_regs_from_user(struct kernel_vm86_regs * regs,const struct vm86_regs __user * user,unsigned extra)112 static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs,
113 const struct vm86_regs __user *user,
114 unsigned extra)
115 {
116 int ret = 0;
117
118 /* copy ax-fs inclusive */
119 ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.orig_ax));
120 /* copy orig_ax-__gsh+extra */
121 ret += copy_from_user(®s->pt.orig_ax, &user->orig_eax,
122 sizeof(struct kernel_vm86_regs) -
123 offsetof(struct kernel_vm86_regs, pt.orig_ax) +
124 extra);
125 return ret;
126 }
127
save_v86_state(struct kernel_vm86_regs * regs)128 struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
129 {
130 struct tss_struct *tss;
131 struct pt_regs *ret;
132 unsigned long tmp;
133
134 /*
135 * This gets called from entry.S with interrupts disabled, but
136 * from process context. Enable interrupts here, before trying
137 * to access user space.
138 */
139 local_irq_enable();
140
141 if (!current->thread.vm86_info) {
142 pr_alert("no vm86_info: BAD\n");
143 do_exit(SIGSEGV);
144 }
145 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | current->thread.v86mask);
146 tmp = copy_vm86_regs_to_user(¤t->thread.vm86_info->regs, regs);
147 tmp += put_user(current->thread.screen_bitmap, ¤t->thread.vm86_info->screen_bitmap);
148 if (tmp) {
149 pr_alert("could not access userspace vm86_info\n");
150 do_exit(SIGSEGV);
151 }
152
153 tss = &per_cpu(init_tss, get_cpu());
154 current->thread.sp0 = current->thread.saved_sp0;
155 current->thread.sysenter_cs = __KERNEL_CS;
156 load_sp0(tss, ¤t->thread);
157 current->thread.saved_sp0 = 0;
158 put_cpu();
159
160 ret = KVM86->regs32;
161
162 ret->fs = current->thread.saved_fs;
163 set_user_gs(ret, current->thread.saved_gs);
164
165 return ret;
166 }
167
mark_screen_rdonly(struct mm_struct * mm)168 static void mark_screen_rdonly(struct mm_struct *mm)
169 {
170 pgd_t *pgd;
171 pud_t *pud;
172 pmd_t *pmd;
173 pte_t *pte;
174 spinlock_t *ptl;
175 int i;
176
177 down_write(&mm->mmap_sem);
178 pgd = pgd_offset(mm, 0xA0000);
179 if (pgd_none_or_clear_bad(pgd))
180 goto out;
181 pud = pud_offset(pgd, 0xA0000);
182 if (pud_none_or_clear_bad(pud))
183 goto out;
184 pmd = pmd_offset(pud, 0xA0000);
185 split_huge_page_pmd_mm(mm, 0xA0000, pmd);
186 if (pmd_none_or_clear_bad(pmd))
187 goto out;
188 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
189 for (i = 0; i < 32; i++) {
190 if (pte_present(*pte))
191 set_pte(pte, pte_wrprotect(*pte));
192 pte++;
193 }
194 pte_unmap_unlock(pte, ptl);
195 out:
196 up_write(&mm->mmap_sem);
197 flush_tlb();
198 }
199
200
201
202 static int do_vm86_irq_handling(int subfunction, int irqnumber);
203 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
204
SYSCALL_DEFINE1(vm86old,struct vm86_struct __user *,v86)205 SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86)
206 {
207 struct kernel_vm86_struct info; /* declare this _on top_,
208 * this avoids wasting of stack space.
209 * This remains on the stack until we
210 * return to 32 bit user space.
211 */
212 struct task_struct *tsk = current;
213 int tmp;
214
215 if (tsk->thread.saved_sp0)
216 return -EPERM;
217 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
218 offsetof(struct kernel_vm86_struct, vm86plus) -
219 sizeof(info.regs));
220 if (tmp)
221 return -EFAULT;
222 memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
223 info.regs32 = current_pt_regs();
224 tsk->thread.vm86_info = v86;
225 do_sys_vm86(&info, tsk);
226 return 0; /* we never return here */
227 }
228
229
SYSCALL_DEFINE2(vm86,unsigned long,cmd,unsigned long,arg)230 SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
231 {
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.
236 */
237 struct task_struct *tsk;
238 int tmp;
239 struct vm86plus_struct __user *v86;
240
241 tsk = current;
242 switch (cmd) {
243 case VM86_REQUEST_IRQ:
244 case VM86_FREE_IRQ:
245 case VM86_GET_IRQ_BITS:
246 case VM86_GET_AND_RESET_IRQ:
247 return do_vm86_irq_handling(cmd, (int)arg);
248 case VM86_PLUS_INSTALL_CHECK:
249 /*
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.
254 */
255 return 0;
256 }
257
258 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
259 if (tsk->thread.saved_sp0)
260 return -EPERM;
261 v86 = (struct vm86plus_struct __user *)arg;
262 tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
263 offsetof(struct kernel_vm86_struct, regs32) -
264 sizeof(info.regs));
265 if (tmp)
266 return -EFAULT;
267 info.regs32 = current_pt_regs();
268 info.vm86plus.is_vm86pus = 1;
269 tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
270 do_sys_vm86(&info, tsk);
271 return 0; /* we never return here */
272 }
273
274
do_sys_vm86(struct kernel_vm86_struct * info,struct task_struct * tsk)275 static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
276 {
277 struct tss_struct *tss;
278 /*
279 * make sure the vm86() system call doesn't try to do anything silly
280 */
281 info->regs.pt.ds = 0;
282 info->regs.pt.es = 0;
283 info->regs.pt.fs = 0;
284 #ifndef CONFIG_X86_32_LAZY_GS
285 info->regs.pt.gs = 0;
286 #endif
287
288 /*
289 * The flags register is also special: we cannot trust that the user
290 * has set it up safely, so this makes sure interrupt etc flags are
291 * inherited from protected mode.
292 */
293 VEFLAGS = info->regs.pt.flags;
294 info->regs.pt.flags &= SAFE_MASK;
295 info->regs.pt.flags |= info->regs32->flags & ~SAFE_MASK;
296 info->regs.pt.flags |= X86_VM_MASK;
297
298 switch (info->cpu_type) {
299 case CPU_286:
300 tsk->thread.v86mask = 0;
301 break;
302 case CPU_386:
303 tsk->thread.v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
304 break;
305 case CPU_486:
306 tsk->thread.v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
307 break;
308 default:
309 tsk->thread.v86mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
310 break;
311 }
312
313 /*
314 * Save old state, set default return value (%ax) to 0 (VM86_SIGNAL)
315 */
316 info->regs32->ax = VM86_SIGNAL;
317 tsk->thread.saved_sp0 = tsk->thread.sp0;
318 tsk->thread.saved_fs = info->regs32->fs;
319 tsk->thread.saved_gs = get_user_gs(info->regs32);
320
321 tss = &per_cpu(init_tss, get_cpu());
322 tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0;
323 if (cpu_has_sep)
324 tsk->thread.sysenter_cs = 0;
325 load_sp0(tss, &tsk->thread);
326 put_cpu();
327
328 tsk->thread.screen_bitmap = info->screen_bitmap;
329 if (info->flags & VM86_SCREEN_BITMAP)
330 mark_screen_rdonly(tsk->mm);
331
332 /*call __audit_syscall_exit since we do not exit via the normal paths */
333 #ifdef CONFIG_AUDITSYSCALL
334 if (unlikely(current->audit_context))
335 __audit_syscall_exit(1, 0);
336 #endif
337
338 __asm__ __volatile__(
339 "movl %0,%%esp\n\t"
340 "movl %1,%%ebp\n\t"
341 #ifdef CONFIG_X86_32_LAZY_GS
342 "mov %2, %%gs\n\t"
343 #endif
344 "jmp resume_userspace"
345 : /* no outputs */
346 :"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0));
347 /* we never return here */
348 }
349
return_to_32bit(struct kernel_vm86_regs * regs16,int retval)350 static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval)
351 {
352 struct pt_regs *regs32;
353
354 regs32 = save_v86_state(regs16);
355 regs32->ax = retval;
356 __asm__ __volatile__("movl %0,%%esp\n\t"
357 "movl %1,%%ebp\n\t"
358 "jmp resume_userspace"
359 : : "r" (regs32), "r" (current_thread_info()));
360 }
361
set_IF(struct kernel_vm86_regs * regs)362 static inline void set_IF(struct kernel_vm86_regs *regs)
363 {
364 VEFLAGS |= X86_EFLAGS_VIF;
365 if (VEFLAGS & X86_EFLAGS_VIP)
366 return_to_32bit(regs, VM86_STI);
367 }
368
clear_IF(struct kernel_vm86_regs * regs)369 static inline void clear_IF(struct kernel_vm86_regs *regs)
370 {
371 VEFLAGS &= ~X86_EFLAGS_VIF;
372 }
373
clear_TF(struct kernel_vm86_regs * regs)374 static inline void clear_TF(struct kernel_vm86_regs *regs)
375 {
376 regs->pt.flags &= ~X86_EFLAGS_TF;
377 }
378
clear_AC(struct kernel_vm86_regs * regs)379 static inline void clear_AC(struct kernel_vm86_regs *regs)
380 {
381 regs->pt.flags &= ~X86_EFLAGS_AC;
382 }
383
384 /*
385 * It is correct to call set_IF(regs) from the set_vflags_*
386 * functions. However someone forgot to call clear_IF(regs)
387 * in the opposite case.
388 * After the command sequence CLI PUSHF STI POPF you should
389 * end up with interrupts disabled, but you ended up with
390 * interrupts enabled.
391 * ( I was testing my own changes, but the only bug I
392 * could find was in a function I had not changed. )
393 * [KD]
394 */
395
set_vflags_long(unsigned long flags,struct kernel_vm86_regs * regs)396 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs)
397 {
398 set_flags(VEFLAGS, flags, current->thread.v86mask);
399 set_flags(regs->pt.flags, flags, SAFE_MASK);
400 if (flags & X86_EFLAGS_IF)
401 set_IF(regs);
402 else
403 clear_IF(regs);
404 }
405
set_vflags_short(unsigned short flags,struct kernel_vm86_regs * regs)406 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs)
407 {
408 set_flags(VFLAGS, flags, current->thread.v86mask);
409 set_flags(regs->pt.flags, flags, SAFE_MASK);
410 if (flags & X86_EFLAGS_IF)
411 set_IF(regs);
412 else
413 clear_IF(regs);
414 }
415
get_vflags(struct kernel_vm86_regs * regs)416 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs)
417 {
418 unsigned long flags = regs->pt.flags & RETURN_MASK;
419
420 if (VEFLAGS & X86_EFLAGS_VIF)
421 flags |= X86_EFLAGS_IF;
422 flags |= X86_EFLAGS_IOPL;
423 return flags | (VEFLAGS & current->thread.v86mask);
424 }
425
is_revectored(int nr,struct revectored_struct * bitmap)426 static inline int is_revectored(int nr, struct revectored_struct *bitmap)
427 {
428 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
429 :"=r" (nr)
430 :"m" (*bitmap), "r" (nr));
431 return nr;
432 }
433
434 #define val_byte(val, n) (((__u8 *)&val)[n])
435
436 #define pushb(base, ptr, val, err_label) \
437 do { \
438 __u8 __val = val; \
439 ptr--; \
440 if (put_user(__val, base + ptr) < 0) \
441 goto err_label; \
442 } while (0)
443
444 #define pushw(base, ptr, val, err_label) \
445 do { \
446 __u16 __val = val; \
447 ptr--; \
448 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
449 goto err_label; \
450 ptr--; \
451 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
452 goto err_label; \
453 } while (0)
454
455 #define pushl(base, ptr, val, err_label) \
456 do { \
457 __u32 __val = val; \
458 ptr--; \
459 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
460 goto err_label; \
461 ptr--; \
462 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
463 goto err_label; \
464 ptr--; \
465 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
466 goto err_label; \
467 ptr--; \
468 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
469 goto err_label; \
470 } while (0)
471
472 #define popb(base, ptr, err_label) \
473 ({ \
474 __u8 __res; \
475 if (get_user(__res, base + ptr) < 0) \
476 goto err_label; \
477 ptr++; \
478 __res; \
479 })
480
481 #define popw(base, ptr, err_label) \
482 ({ \
483 __u16 __res; \
484 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
485 goto err_label; \
486 ptr++; \
487 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
488 goto err_label; \
489 ptr++; \
490 __res; \
491 })
492
493 #define popl(base, ptr, err_label) \
494 ({ \
495 __u32 __res; \
496 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
497 goto err_label; \
498 ptr++; \
499 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
500 goto err_label; \
501 ptr++; \
502 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
503 goto err_label; \
504 ptr++; \
505 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
506 goto err_label; \
507 ptr++; \
508 __res; \
509 })
510
511 /* There are so many possible reasons for this function to return
512 * VM86_INTx, so adding another doesn't bother me. We can expect
513 * userspace programs to be able to handle it. (Getting a problem
514 * in userspace is always better than an Oops anyway.) [KD]
515 */
do_int(struct kernel_vm86_regs * regs,int i,unsigned char __user * ssp,unsigned short sp)516 static void do_int(struct kernel_vm86_regs *regs, int i,
517 unsigned char __user *ssp, unsigned short sp)
518 {
519 unsigned long __user *intr_ptr;
520 unsigned long segoffs;
521
522 if (regs->pt.cs == BIOSSEG)
523 goto cannot_handle;
524 if (is_revectored(i, &KVM86->int_revectored))
525 goto cannot_handle;
526 if (i == 0x21 && is_revectored(AH(regs), &KVM86->int21_revectored))
527 goto cannot_handle;
528 intr_ptr = (unsigned long __user *) (i << 2);
529 if (get_user(segoffs, intr_ptr))
530 goto cannot_handle;
531 if ((segoffs >> 16) == BIOSSEG)
532 goto cannot_handle;
533 pushw(ssp, sp, get_vflags(regs), cannot_handle);
534 pushw(ssp, sp, regs->pt.cs, cannot_handle);
535 pushw(ssp, sp, IP(regs), cannot_handle);
536 regs->pt.cs = segoffs >> 16;
537 SP(regs) -= 6;
538 IP(regs) = segoffs & 0xffff;
539 clear_TF(regs);
540 clear_IF(regs);
541 clear_AC(regs);
542 return;
543
544 cannot_handle:
545 return_to_32bit(regs, VM86_INTx + (i << 8));
546 }
547
handle_vm86_trap(struct kernel_vm86_regs * regs,long error_code,int trapno)548 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno)
549 {
550 if (VMPI.is_vm86pus) {
551 if ((trapno == 3) || (trapno == 1)) {
552 KVM86->regs32->ax = VM86_TRAP + (trapno << 8);
553 /* setting this flag forces the code in entry_32.S to
554 the path where we call save_v86_state() and change
555 the stack pointer to KVM86->regs32 */
556 set_thread_flag(TIF_NOTIFY_RESUME);
557 return 0;
558 }
559 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs));
560 return 0;
561 }
562 if (trapno != 1)
563 return 1; /* we let this handle by the calling routine */
564 current->thread.trap_nr = trapno;
565 current->thread.error_code = error_code;
566 force_sig(SIGTRAP, current);
567 return 0;
568 }
569
handle_vm86_fault(struct kernel_vm86_regs * regs,long error_code)570 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code)
571 {
572 unsigned char opcode;
573 unsigned char __user *csp;
574 unsigned char __user *ssp;
575 unsigned short ip, sp, orig_flags;
576 int data32, pref_done;
577
578 #define CHECK_IF_IN_TRAP \
579 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
580 newflags |= X86_EFLAGS_TF
581 #define VM86_FAULT_RETURN do { \
582 if (VMPI.force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \
583 return_to_32bit(regs, VM86_PICRETURN); \
584 if (orig_flags & X86_EFLAGS_TF) \
585 handle_vm86_trap(regs, 0, 1); \
586 return; } while (0)
587
588 orig_flags = *(unsigned short *)®s->pt.flags;
589
590 csp = (unsigned char __user *) (regs->pt.cs << 4);
591 ssp = (unsigned char __user *) (regs->pt.ss << 4);
592 sp = SP(regs);
593 ip = IP(regs);
594
595 data32 = 0;
596 pref_done = 0;
597 do {
598 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
599 case 0x66: /* 32-bit data */ data32 = 1; break;
600 case 0x67: /* 32-bit address */ break;
601 case 0x2e: /* CS */ break;
602 case 0x3e: /* DS */ break;
603 case 0x26: /* ES */ break;
604 case 0x36: /* SS */ break;
605 case 0x65: /* GS */ break;
606 case 0x64: /* FS */ break;
607 case 0xf2: /* repnz */ break;
608 case 0xf3: /* rep */ break;
609 default: pref_done = 1;
610 }
611 } while (!pref_done);
612
613 switch (opcode) {
614
615 /* pushf */
616 case 0x9c:
617 if (data32) {
618 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
619 SP(regs) -= 4;
620 } else {
621 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
622 SP(regs) -= 2;
623 }
624 IP(regs) = ip;
625 VM86_FAULT_RETURN;
626
627 /* popf */
628 case 0x9d:
629 {
630 unsigned long newflags;
631 if (data32) {
632 newflags = popl(ssp, sp, simulate_sigsegv);
633 SP(regs) += 4;
634 } else {
635 newflags = popw(ssp, sp, simulate_sigsegv);
636 SP(regs) += 2;
637 }
638 IP(regs) = ip;
639 CHECK_IF_IN_TRAP;
640 if (data32)
641 set_vflags_long(newflags, regs);
642 else
643 set_vflags_short(newflags, regs);
644
645 VM86_FAULT_RETURN;
646 }
647
648 /* int xx */
649 case 0xcd: {
650 int intno = popb(csp, ip, simulate_sigsegv);
651 IP(regs) = ip;
652 if (VMPI.vm86dbg_active) {
653 if ((1 << (intno & 7)) & VMPI.vm86dbg_intxxtab[intno >> 3])
654 return_to_32bit(regs, VM86_INTx + (intno << 8));
655 }
656 do_int(regs, intno, ssp, sp);
657 return;
658 }
659
660 /* iret */
661 case 0xcf:
662 {
663 unsigned long newip;
664 unsigned long newcs;
665 unsigned long newflags;
666 if (data32) {
667 newip = popl(ssp, sp, simulate_sigsegv);
668 newcs = popl(ssp, sp, simulate_sigsegv);
669 newflags = popl(ssp, sp, simulate_sigsegv);
670 SP(regs) += 12;
671 } else {
672 newip = popw(ssp, sp, simulate_sigsegv);
673 newcs = popw(ssp, sp, simulate_sigsegv);
674 newflags = popw(ssp, sp, simulate_sigsegv);
675 SP(regs) += 6;
676 }
677 IP(regs) = newip;
678 regs->pt.cs = newcs;
679 CHECK_IF_IN_TRAP;
680 if (data32) {
681 set_vflags_long(newflags, regs);
682 } else {
683 set_vflags_short(newflags, regs);
684 }
685 VM86_FAULT_RETURN;
686 }
687
688 /* cli */
689 case 0xfa:
690 IP(regs) = ip;
691 clear_IF(regs);
692 VM86_FAULT_RETURN;
693
694 /* sti */
695 /*
696 * Damn. This is incorrect: the 'sti' instruction should actually
697 * enable interrupts after the /next/ instruction. Not good.
698 *
699 * Probably needs some horsing around with the TF flag. Aiee..
700 */
701 case 0xfb:
702 IP(regs) = ip;
703 set_IF(regs);
704 VM86_FAULT_RETURN;
705
706 default:
707 return_to_32bit(regs, VM86_UNKNOWN);
708 }
709
710 return;
711
712 simulate_sigsegv:
713 /* FIXME: After a long discussion with Stas we finally
714 * agreed, that this is wrong. Here we should
715 * really send a SIGSEGV to the user program.
716 * But how do we create the correct context? We
717 * are inside a general protection fault handler
718 * and has just returned from a page fault handler.
719 * The correct context for the signal handler
720 * should be a mixture of the two, but how do we
721 * get the information? [KD]
722 */
723 return_to_32bit(regs, VM86_UNKNOWN);
724 }
725
726 /* ---------------- vm86 special IRQ passing stuff ----------------- */
727
728 #define VM86_IRQNAME "vm86irq"
729
730 static struct vm86_irqs {
731 struct task_struct *tsk;
732 int sig;
733 } vm86_irqs[16];
734
735 static DEFINE_SPINLOCK(irqbits_lock);
736 static int irqbits;
737
738 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \
739 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
740 | (1 << SIGUNUSED))
741
irq_handler(int intno,void * dev_id)742 static irqreturn_t irq_handler(int intno, void *dev_id)
743 {
744 int irq_bit;
745 unsigned long flags;
746
747 spin_lock_irqsave(&irqbits_lock, flags);
748 irq_bit = 1 << intno;
749 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk)
750 goto out;
751 irqbits |= irq_bit;
752 if (vm86_irqs[intno].sig)
753 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
754 /*
755 * IRQ will be re-enabled when user asks for the irq (whether
756 * polling or as a result of the signal)
757 */
758 disable_irq_nosync(intno);
759 spin_unlock_irqrestore(&irqbits_lock, flags);
760 return IRQ_HANDLED;
761
762 out:
763 spin_unlock_irqrestore(&irqbits_lock, flags);
764 return IRQ_NONE;
765 }
766
free_vm86_irq(int irqnumber)767 static inline void free_vm86_irq(int irqnumber)
768 {
769 unsigned long flags;
770
771 free_irq(irqnumber, NULL);
772 vm86_irqs[irqnumber].tsk = NULL;
773
774 spin_lock_irqsave(&irqbits_lock, flags);
775 irqbits &= ~(1 << irqnumber);
776 spin_unlock_irqrestore(&irqbits_lock, flags);
777 }
778
release_vm86_irqs(struct task_struct * task)779 void release_vm86_irqs(struct task_struct *task)
780 {
781 int i;
782 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
783 if (vm86_irqs[i].tsk == task)
784 free_vm86_irq(i);
785 }
786
get_and_reset_irq(int irqnumber)787 static inline int get_and_reset_irq(int irqnumber)
788 {
789 int bit;
790 unsigned long flags;
791 int ret = 0;
792
793 if (invalid_vm86_irq(irqnumber)) return 0;
794 if (vm86_irqs[irqnumber].tsk != current) return 0;
795 spin_lock_irqsave(&irqbits_lock, flags);
796 bit = irqbits & (1 << irqnumber);
797 irqbits &= ~bit;
798 if (bit) {
799 enable_irq(irqnumber);
800 ret = 1;
801 }
802
803 spin_unlock_irqrestore(&irqbits_lock, flags);
804 return ret;
805 }
806
807
do_vm86_irq_handling(int subfunction,int irqnumber)808 static int do_vm86_irq_handling(int subfunction, int irqnumber)
809 {
810 int ret;
811 switch (subfunction) {
812 case VM86_GET_AND_RESET_IRQ: {
813 return get_and_reset_irq(irqnumber);
814 }
815 case VM86_GET_IRQ_BITS: {
816 return irqbits;
817 }
818 case VM86_REQUEST_IRQ: {
819 int sig = irqnumber >> 8;
820 int irq = irqnumber & 255;
821 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
822 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
823 if (invalid_vm86_irq(irq)) return -EPERM;
824 if (vm86_irqs[irq].tsk) return -EPERM;
825 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL);
826 if (ret) return ret;
827 vm86_irqs[irq].sig = sig;
828 vm86_irqs[irq].tsk = current;
829 return irq;
830 }
831 case VM86_FREE_IRQ: {
832 if (invalid_vm86_irq(irqnumber)) return -EPERM;
833 if (!vm86_irqs[irqnumber].tsk) return 0;
834 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
835 free_vm86_irq(irqnumber);
836 return 0;
837 }
838 }
839 return -EINVAL;
840 }
841
842