1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright (C) 1994 Linus Torvalds |
4 | * |
5 | * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86 |
6 | * stack - Manfred Spraul <manfred@colorfullife.com> |
7 | * |
8 | * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle |
9 | * them correctly. Now the emulation will be in a |
10 | * consistent state after stackfaults - Kasper Dupont |
11 | * <kasperd@daimi.au.dk> |
12 | * |
13 | * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont |
14 | * <kasperd@daimi.au.dk> |
15 | * |
16 | * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault |
17 | * caused by Kasper Dupont's changes - Stas Sergeev |
18 | * |
19 | * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes. |
20 | * Kasper Dupont <kasperd@daimi.au.dk> |
21 | * |
22 | * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault. |
23 | * Kasper Dupont <kasperd@daimi.au.dk> |
24 | * |
25 | * 9 apr 2002 - Changed stack access macros to jump to a label |
26 | * instead of returning to userspace. This simplifies |
27 | * do_int, and is needed by handle_vm6_fault. Kasper |
28 | * Dupont <kasperd@daimi.au.dk> |
29 | * |
30 | */ |
31 | |
32 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
33 | |
34 | #include <linux/capability.h> |
35 | #include <linux/errno.h> |
36 | #include <linux/interrupt.h> |
37 | #include <linux/syscalls.h> |
38 | #include <linux/sched.h> |
39 | #include <linux/sched/task_stack.h> |
40 | #include <linux/kernel.h> |
41 | #include <linux/signal.h> |
42 | #include <linux/string.h> |
43 | #include <linux/mm.h> |
44 | #include <linux/smp.h> |
45 | #include <linux/highmem.h> |
46 | #include <linux/ptrace.h> |
47 | #include <linux/audit.h> |
48 | #include <linux/stddef.h> |
49 | #include <linux/slab.h> |
50 | #include <linux/security.h> |
51 | |
52 | #include <linux/uaccess.h> |
53 | #include <asm/io.h> |
54 | #include <asm/tlbflush.h> |
55 | #include <asm/irq.h> |
56 | #include <asm/traps.h> |
57 | #include <asm/vm86.h> |
58 | #include <asm/switch_to.h> |
59 | |
60 | /* |
61 | * Known problems: |
62 | * |
63 | * Interrupt handling is not guaranteed: |
64 | * - a real x86 will disable all interrupts for one instruction |
65 | * after a "mov ss,xx" to make stack handling atomic even without |
66 | * the 'lss' instruction. We can't guarantee this in v86 mode, |
67 | * as the next instruction might result in a page fault or similar. |
68 | * - a real x86 will have interrupts disabled for one instruction |
69 | * past the 'sti' that enables them. We don't bother with all the |
70 | * details yet. |
71 | * |
72 | * Let's hope these problems do not actually matter for anything. |
73 | */ |
74 | |
75 | |
76 | /* |
77 | * 8- and 16-bit register defines.. |
78 | */ |
79 | #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0]) |
80 | #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1]) |
81 | #define IP(regs) (*(unsigned short *)&((regs)->pt.ip)) |
82 | #define SP(regs) (*(unsigned short *)&((regs)->pt.sp)) |
83 | |
84 | /* |
85 | * virtual flags (16 and 32-bit versions) |
86 | */ |
87 | #define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags)) |
88 | #define VEFLAGS (current->thread.vm86->veflags) |
89 | |
90 | #define set_flags(X, new, mask) \ |
91 | ((X) = ((X) & ~(mask)) | ((new) & (mask))) |
92 | |
93 | #define SAFE_MASK (0xDD5) |
94 | #define RETURN_MASK (0xDFF) |
95 | |
96 | void save_v86_state(struct kernel_vm86_regs *regs, int retval) |
97 | { |
98 | struct task_struct *tsk = current; |
99 | struct vm86plus_struct __user *user; |
100 | struct vm86 *vm86 = current->thread.vm86; |
101 | |
102 | /* |
103 | * This gets called from entry.S with interrupts disabled, but |
104 | * from process context. Enable interrupts here, before trying |
105 | * to access user space. |
106 | */ |
107 | local_irq_enable(); |
108 | |
109 | BUG_ON(!vm86); |
110 | |
111 | set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask); |
112 | user = vm86->user_vm86; |
113 | |
114 | if (!user_access_begin(user, vm86->vm86plus.is_vm86pus ? |
115 | sizeof(struct vm86plus_struct) : |
116 | sizeof(struct vm86_struct))) |
117 | goto Efault; |
118 | |
119 | unsafe_put_user(regs->pt.bx, &user->regs.ebx, Efault_end); |
120 | unsafe_put_user(regs->pt.cx, &user->regs.ecx, Efault_end); |
121 | unsafe_put_user(regs->pt.dx, &user->regs.edx, Efault_end); |
122 | unsafe_put_user(regs->pt.si, &user->regs.esi, Efault_end); |
123 | unsafe_put_user(regs->pt.di, &user->regs.edi, Efault_end); |
124 | unsafe_put_user(regs->pt.bp, &user->regs.ebp, Efault_end); |
125 | unsafe_put_user(regs->pt.ax, &user->regs.eax, Efault_end); |
126 | unsafe_put_user(regs->pt.ip, &user->regs.eip, Efault_end); |
127 | unsafe_put_user(regs->pt.cs, &user->regs.cs, Efault_end); |
128 | unsafe_put_user(regs->pt.flags, &user->regs.eflags, Efault_end); |
129 | unsafe_put_user(regs->pt.sp, &user->regs.esp, Efault_end); |
130 | unsafe_put_user(regs->pt.ss, &user->regs.ss, Efault_end); |
131 | unsafe_put_user(regs->es, &user->regs.es, Efault_end); |
132 | unsafe_put_user(regs->ds, &user->regs.ds, Efault_end); |
133 | unsafe_put_user(regs->fs, &user->regs.fs, Efault_end); |
134 | unsafe_put_user(regs->gs, &user->regs.gs, Efault_end); |
135 | |
136 | /* |
137 | * Don't write screen_bitmap in case some user had a value there |
138 | * and expected it to remain unchanged. |
139 | */ |
140 | |
141 | user_access_end(); |
142 | |
143 | exit_vm86: |
144 | preempt_disable(); |
145 | tsk->thread.sp0 = vm86->saved_sp0; |
146 | tsk->thread.sysenter_cs = __KERNEL_CS; |
147 | update_task_stack(task: tsk); |
148 | refresh_sysenter_cs(&tsk->thread); |
149 | vm86->saved_sp0 = 0; |
150 | preempt_enable(); |
151 | |
152 | memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs)); |
153 | |
154 | loadsegment(gs, vm86->regs32.gs); |
155 | |
156 | regs->pt.ax = retval; |
157 | return; |
158 | |
159 | Efault_end: |
160 | user_access_end(); |
161 | Efault: |
162 | pr_alert("could not access userspace vm86 info\n" ); |
163 | force_exit_sig(SIGSEGV); |
164 | goto exit_vm86; |
165 | } |
166 | |
167 | static int do_vm86_irq_handling(int subfunction, int irqnumber); |
168 | static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus); |
169 | |
170 | SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86) |
171 | { |
172 | return do_sys_vm86(user_vm86: (struct vm86plus_struct __user *) user_vm86, plus: false); |
173 | } |
174 | |
175 | |
176 | SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) |
177 | { |
178 | switch (cmd) { |
179 | case VM86_REQUEST_IRQ: |
180 | case VM86_FREE_IRQ: |
181 | case VM86_GET_IRQ_BITS: |
182 | case VM86_GET_AND_RESET_IRQ: |
183 | return do_vm86_irq_handling(subfunction: cmd, irqnumber: (int)arg); |
184 | case VM86_PLUS_INSTALL_CHECK: |
185 | /* |
186 | * NOTE: on old vm86 stuff this will return the error |
187 | * from access_ok(), because the subfunction is |
188 | * interpreted as (invalid) address to vm86_struct. |
189 | * So the installation check works. |
190 | */ |
191 | return 0; |
192 | } |
193 | |
194 | /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ |
195 | return do_sys_vm86(user_vm86: (struct vm86plus_struct __user *) arg, plus: true); |
196 | } |
197 | |
198 | |
199 | static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus) |
200 | { |
201 | struct task_struct *tsk = current; |
202 | struct vm86 *vm86 = tsk->thread.vm86; |
203 | struct kernel_vm86_regs vm86regs; |
204 | struct pt_regs *regs = current_pt_regs(); |
205 | unsigned long err = 0; |
206 | struct vm86_struct v; |
207 | |
208 | err = security_mmap_addr(addr: 0); |
209 | if (err) { |
210 | /* |
211 | * vm86 cannot virtualize the address space, so vm86 users |
212 | * need to manage the low 1MB themselves using mmap. Given |
213 | * that BIOS places important data in the first page, vm86 |
214 | * is essentially useless if mmap_min_addr != 0. DOSEMU, |
215 | * for example, won't even bother trying to use vm86 if it |
216 | * can't map a page at virtual address 0. |
217 | * |
218 | * To reduce the available kernel attack surface, simply |
219 | * disallow vm86(old) for users who cannot mmap at va 0. |
220 | * |
221 | * The implementation of security_mmap_addr will allow |
222 | * suitably privileged users to map va 0 even if |
223 | * vm.mmap_min_addr is set above 0, and we want this |
224 | * behavior for vm86 as well, as it ensures that legacy |
225 | * tools like vbetool will not fail just because of |
226 | * vm.mmap_min_addr. |
227 | */ |
228 | pr_info_once("Denied a call to vm86(old) from %s[%d] (uid: %d). Set the vm.mmap_min_addr sysctl to 0 and/or adjust LSM mmap_min_addr policy to enable vm86 if you are using a vm86-based DOS emulator.\n" , |
229 | current->comm, task_pid_nr(current), |
230 | from_kuid_munged(&init_user_ns, current_uid())); |
231 | return -EPERM; |
232 | } |
233 | |
234 | if (!vm86) { |
235 | if (!(vm86 = kzalloc(size: sizeof(*vm86), GFP_KERNEL))) |
236 | return -ENOMEM; |
237 | tsk->thread.vm86 = vm86; |
238 | } |
239 | if (vm86->saved_sp0) |
240 | return -EPERM; |
241 | |
242 | if (copy_from_user(to: &v, from: user_vm86, |
243 | offsetof(struct vm86_struct, int_revectored))) |
244 | return -EFAULT; |
245 | |
246 | |
247 | /* VM86_SCREEN_BITMAP had numerous bugs and appears to have no users. */ |
248 | if (v.flags & VM86_SCREEN_BITMAP) { |
249 | char comm[TASK_COMM_LEN]; |
250 | |
251 | pr_info_once("vm86: '%s' uses VM86_SCREEN_BITMAP, which is no longer supported\n" , get_task_comm(comm, current)); |
252 | return -EINVAL; |
253 | } |
254 | |
255 | memset(&vm86regs, 0, sizeof(vm86regs)); |
256 | |
257 | vm86regs.pt.bx = v.regs.ebx; |
258 | vm86regs.pt.cx = v.regs.ecx; |
259 | vm86regs.pt.dx = v.regs.edx; |
260 | vm86regs.pt.si = v.regs.esi; |
261 | vm86regs.pt.di = v.regs.edi; |
262 | vm86regs.pt.bp = v.regs.ebp; |
263 | vm86regs.pt.ax = v.regs.eax; |
264 | vm86regs.pt.ip = v.regs.eip; |
265 | vm86regs.pt.cs = v.regs.cs; |
266 | vm86regs.pt.flags = v.regs.eflags; |
267 | vm86regs.pt.sp = v.regs.esp; |
268 | vm86regs.pt.ss = v.regs.ss; |
269 | vm86regs.es = v.regs.es; |
270 | vm86regs.ds = v.regs.ds; |
271 | vm86regs.fs = v.regs.fs; |
272 | vm86regs.gs = v.regs.gs; |
273 | |
274 | vm86->flags = v.flags; |
275 | vm86->cpu_type = v.cpu_type; |
276 | |
277 | if (copy_from_user(to: &vm86->int_revectored, |
278 | from: &user_vm86->int_revectored, |
279 | n: sizeof(struct revectored_struct))) |
280 | return -EFAULT; |
281 | if (copy_from_user(to: &vm86->int21_revectored, |
282 | from: &user_vm86->int21_revectored, |
283 | n: sizeof(struct revectored_struct))) |
284 | return -EFAULT; |
285 | if (plus) { |
286 | if (copy_from_user(to: &vm86->vm86plus, from: &user_vm86->vm86plus, |
287 | n: sizeof(struct vm86plus_info_struct))) |
288 | return -EFAULT; |
289 | vm86->vm86plus.is_vm86pus = 1; |
290 | } else |
291 | memset(&vm86->vm86plus, 0, |
292 | sizeof(struct vm86plus_info_struct)); |
293 | |
294 | memcpy(&vm86->regs32, regs, sizeof(struct pt_regs)); |
295 | vm86->user_vm86 = user_vm86; |
296 | |
297 | /* |
298 | * The flags register is also special: we cannot trust that the user |
299 | * has set it up safely, so this makes sure interrupt etc flags are |
300 | * inherited from protected mode. |
301 | */ |
302 | VEFLAGS = vm86regs.pt.flags; |
303 | vm86regs.pt.flags &= SAFE_MASK; |
304 | vm86regs.pt.flags |= regs->flags & ~SAFE_MASK; |
305 | vm86regs.pt.flags |= X86_VM_MASK; |
306 | |
307 | vm86regs.pt.orig_ax = regs->orig_ax; |
308 | |
309 | switch (vm86->cpu_type) { |
310 | case CPU_286: |
311 | vm86->veflags_mask = 0; |
312 | break; |
313 | case CPU_386: |
314 | vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; |
315 | break; |
316 | case CPU_486: |
317 | vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; |
318 | break; |
319 | default: |
320 | vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; |
321 | break; |
322 | } |
323 | |
324 | /* |
325 | * Save old state |
326 | */ |
327 | vm86->saved_sp0 = tsk->thread.sp0; |
328 | savesegment(gs, vm86->regs32.gs); |
329 | |
330 | /* make room for real-mode segments */ |
331 | preempt_disable(); |
332 | tsk->thread.sp0 += 16; |
333 | |
334 | if (boot_cpu_has(X86_FEATURE_SEP)) { |
335 | tsk->thread.sysenter_cs = 0; |
336 | refresh_sysenter_cs(&tsk->thread); |
337 | } |
338 | |
339 | update_task_stack(task: tsk); |
340 | preempt_enable(); |
341 | |
342 | memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs)); |
343 | return regs->ax; |
344 | } |
345 | |
346 | static inline void set_IF(struct kernel_vm86_regs *regs) |
347 | { |
348 | VEFLAGS |= X86_EFLAGS_VIF; |
349 | } |
350 | |
351 | static inline void clear_IF(struct kernel_vm86_regs *regs) |
352 | { |
353 | VEFLAGS &= ~X86_EFLAGS_VIF; |
354 | } |
355 | |
356 | static inline void clear_TF(struct kernel_vm86_regs *regs) |
357 | { |
358 | regs->pt.flags &= ~X86_EFLAGS_TF; |
359 | } |
360 | |
361 | static inline void clear_AC(struct kernel_vm86_regs *regs) |
362 | { |
363 | regs->pt.flags &= ~X86_EFLAGS_AC; |
364 | } |
365 | |
366 | /* |
367 | * It is correct to call set_IF(regs) from the set_vflags_* |
368 | * functions. However someone forgot to call clear_IF(regs) |
369 | * in the opposite case. |
370 | * After the command sequence CLI PUSHF STI POPF you should |
371 | * end up with interrupts disabled, but you ended up with |
372 | * interrupts enabled. |
373 | * ( I was testing my own changes, but the only bug I |
374 | * could find was in a function I had not changed. ) |
375 | * [KD] |
376 | */ |
377 | |
378 | static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) |
379 | { |
380 | set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask); |
381 | set_flags(regs->pt.flags, flags, SAFE_MASK); |
382 | if (flags & X86_EFLAGS_IF) |
383 | set_IF(regs); |
384 | else |
385 | clear_IF(regs); |
386 | } |
387 | |
388 | static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) |
389 | { |
390 | set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask); |
391 | set_flags(regs->pt.flags, flags, SAFE_MASK); |
392 | if (flags & X86_EFLAGS_IF) |
393 | set_IF(regs); |
394 | else |
395 | clear_IF(regs); |
396 | } |
397 | |
398 | static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) |
399 | { |
400 | unsigned long flags = regs->pt.flags & RETURN_MASK; |
401 | |
402 | if (VEFLAGS & X86_EFLAGS_VIF) |
403 | flags |= X86_EFLAGS_IF; |
404 | flags |= X86_EFLAGS_IOPL; |
405 | return flags | (VEFLAGS & current->thread.vm86->veflags_mask); |
406 | } |
407 | |
408 | static inline int is_revectored(int nr, struct revectored_struct *bitmap) |
409 | { |
410 | return test_bit(nr, bitmap->__map); |
411 | } |
412 | |
413 | #define val_byte(val, n) (((__u8 *)&val)[n]) |
414 | |
415 | #define pushb(base, ptr, val, err_label) \ |
416 | do { \ |
417 | __u8 __val = val; \ |
418 | ptr--; \ |
419 | if (put_user(__val, base + ptr) < 0) \ |
420 | goto err_label; \ |
421 | } while (0) |
422 | |
423 | #define pushw(base, ptr, val, err_label) \ |
424 | do { \ |
425 | __u16 __val = val; \ |
426 | ptr--; \ |
427 | if (put_user(val_byte(__val, 1), base + ptr) < 0) \ |
428 | goto err_label; \ |
429 | ptr--; \ |
430 | if (put_user(val_byte(__val, 0), base + ptr) < 0) \ |
431 | goto err_label; \ |
432 | } while (0) |
433 | |
434 | #define pushl(base, ptr, val, err_label) \ |
435 | do { \ |
436 | __u32 __val = val; \ |
437 | ptr--; \ |
438 | if (put_user(val_byte(__val, 3), base + ptr) < 0) \ |
439 | goto err_label; \ |
440 | ptr--; \ |
441 | if (put_user(val_byte(__val, 2), base + ptr) < 0) \ |
442 | goto err_label; \ |
443 | ptr--; \ |
444 | if (put_user(val_byte(__val, 1), base + ptr) < 0) \ |
445 | goto err_label; \ |
446 | ptr--; \ |
447 | if (put_user(val_byte(__val, 0), base + ptr) < 0) \ |
448 | goto err_label; \ |
449 | } while (0) |
450 | |
451 | #define popb(base, ptr, err_label) \ |
452 | ({ \ |
453 | __u8 __res; \ |
454 | if (get_user(__res, base + ptr) < 0) \ |
455 | goto err_label; \ |
456 | ptr++; \ |
457 | __res; \ |
458 | }) |
459 | |
460 | #define popw(base, ptr, err_label) \ |
461 | ({ \ |
462 | __u16 __res; \ |
463 | if (get_user(val_byte(__res, 0), base + ptr) < 0) \ |
464 | goto err_label; \ |
465 | ptr++; \ |
466 | if (get_user(val_byte(__res, 1), base + ptr) < 0) \ |
467 | goto err_label; \ |
468 | ptr++; \ |
469 | __res; \ |
470 | }) |
471 | |
472 | #define popl(base, ptr, err_label) \ |
473 | ({ \ |
474 | __u32 __res; \ |
475 | if (get_user(val_byte(__res, 0), base + ptr) < 0) \ |
476 | goto err_label; \ |
477 | ptr++; \ |
478 | if (get_user(val_byte(__res, 1), base + ptr) < 0) \ |
479 | goto err_label; \ |
480 | ptr++; \ |
481 | if (get_user(val_byte(__res, 2), base + ptr) < 0) \ |
482 | goto err_label; \ |
483 | ptr++; \ |
484 | if (get_user(val_byte(__res, 3), base + ptr) < 0) \ |
485 | goto err_label; \ |
486 | ptr++; \ |
487 | __res; \ |
488 | }) |
489 | |
490 | /* There are so many possible reasons for this function to return |
491 | * VM86_INTx, so adding another doesn't bother me. We can expect |
492 | * userspace programs to be able to handle it. (Getting a problem |
493 | * in userspace is always better than an Oops anyway.) [KD] |
494 | */ |
495 | static void do_int(struct kernel_vm86_regs *regs, int i, |
496 | unsigned char __user *ssp, unsigned short sp) |
497 | { |
498 | unsigned long __user *intr_ptr; |
499 | unsigned long segoffs; |
500 | struct vm86 *vm86 = current->thread.vm86; |
501 | |
502 | if (regs->pt.cs == BIOSSEG) |
503 | goto cannot_handle; |
504 | if (is_revectored(nr: i, bitmap: &vm86->int_revectored)) |
505 | goto cannot_handle; |
506 | if (i == 0x21 && is_revectored(AH(regs), bitmap: &vm86->int21_revectored)) |
507 | goto cannot_handle; |
508 | intr_ptr = (unsigned long __user *) (i << 2); |
509 | if (get_user(segoffs, intr_ptr)) |
510 | goto cannot_handle; |
511 | if ((segoffs >> 16) == BIOSSEG) |
512 | goto cannot_handle; |
513 | pushw(ssp, sp, get_vflags(regs), cannot_handle); |
514 | pushw(ssp, sp, regs->pt.cs, cannot_handle); |
515 | pushw(ssp, sp, IP(regs), cannot_handle); |
516 | regs->pt.cs = segoffs >> 16; |
517 | SP(regs) -= 6; |
518 | IP(regs) = segoffs & 0xffff; |
519 | clear_TF(regs); |
520 | clear_IF(regs); |
521 | clear_AC(regs); |
522 | return; |
523 | |
524 | cannot_handle: |
525 | save_v86_state(regs, VM86_INTx + (i << 8)); |
526 | } |
527 | |
528 | int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) |
529 | { |
530 | struct vm86 *vm86 = current->thread.vm86; |
531 | |
532 | if (vm86->vm86plus.is_vm86pus) { |
533 | if ((trapno == 3) || (trapno == 1)) { |
534 | save_v86_state(regs, VM86_TRAP + (trapno << 8)); |
535 | return 0; |
536 | } |
537 | do_int(regs, i: trapno, ssp: (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); |
538 | return 0; |
539 | } |
540 | if (trapno != 1) |
541 | return 1; /* we let this handle by the calling routine */ |
542 | current->thread.trap_nr = trapno; |
543 | current->thread.error_code = error_code; |
544 | force_sig(SIGTRAP); |
545 | return 0; |
546 | } |
547 | |
548 | void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) |
549 | { |
550 | unsigned char opcode; |
551 | unsigned char __user *csp; |
552 | unsigned char __user *ssp; |
553 | unsigned short ip, sp, orig_flags; |
554 | int data32, pref_done; |
555 | struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; |
556 | |
557 | #define CHECK_IF_IN_TRAP \ |
558 | if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ |
559 | newflags |= X86_EFLAGS_TF |
560 | |
561 | orig_flags = *(unsigned short *)®s->pt.flags; |
562 | |
563 | csp = (unsigned char __user *) (regs->pt.cs << 4); |
564 | ssp = (unsigned char __user *) (regs->pt.ss << 4); |
565 | sp = SP(regs); |
566 | ip = IP(regs); |
567 | |
568 | data32 = 0; |
569 | pref_done = 0; |
570 | do { |
571 | switch (opcode = popb(csp, ip, simulate_sigsegv)) { |
572 | case 0x66: /* 32-bit data */ data32 = 1; break; |
573 | case 0x67: /* 32-bit address */ break; |
574 | case 0x2e: /* CS */ break; |
575 | case 0x3e: /* DS */ break; |
576 | case 0x26: /* ES */ break; |
577 | case 0x36: /* SS */ break; |
578 | case 0x65: /* GS */ break; |
579 | case 0x64: /* FS */ break; |
580 | case 0xf2: /* repnz */ break; |
581 | case 0xf3: /* rep */ break; |
582 | default: pref_done = 1; |
583 | } |
584 | } while (!pref_done); |
585 | |
586 | switch (opcode) { |
587 | |
588 | /* pushf */ |
589 | case 0x9c: |
590 | if (data32) { |
591 | pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); |
592 | SP(regs) -= 4; |
593 | } else { |
594 | pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); |
595 | SP(regs) -= 2; |
596 | } |
597 | IP(regs) = ip; |
598 | goto vm86_fault_return; |
599 | |
600 | /* popf */ |
601 | case 0x9d: |
602 | { |
603 | unsigned long newflags; |
604 | if (data32) { |
605 | newflags = popl(ssp, sp, simulate_sigsegv); |
606 | SP(regs) += 4; |
607 | } else { |
608 | newflags = popw(ssp, sp, simulate_sigsegv); |
609 | SP(regs) += 2; |
610 | } |
611 | IP(regs) = ip; |
612 | CHECK_IF_IN_TRAP; |
613 | if (data32) |
614 | set_vflags_long(newflags, regs); |
615 | else |
616 | set_vflags_short(newflags, regs); |
617 | |
618 | goto check_vip; |
619 | } |
620 | |
621 | /* int xx */ |
622 | case 0xcd: { |
623 | int intno = popb(csp, ip, simulate_sigsegv); |
624 | IP(regs) = ip; |
625 | if (vmpi->vm86dbg_active) { |
626 | if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) { |
627 | save_v86_state(regs, VM86_INTx + (intno << 8)); |
628 | return; |
629 | } |
630 | } |
631 | do_int(regs, intno, ssp, sp); |
632 | return; |
633 | } |
634 | |
635 | /* iret */ |
636 | case 0xcf: |
637 | { |
638 | unsigned long newip; |
639 | unsigned long newcs; |
640 | unsigned long newflags; |
641 | if (data32) { |
642 | newip = popl(ssp, sp, simulate_sigsegv); |
643 | newcs = popl(ssp, sp, simulate_sigsegv); |
644 | newflags = popl(ssp, sp, simulate_sigsegv); |
645 | SP(regs) += 12; |
646 | } else { |
647 | newip = popw(ssp, sp, simulate_sigsegv); |
648 | newcs = popw(ssp, sp, simulate_sigsegv); |
649 | newflags = popw(ssp, sp, simulate_sigsegv); |
650 | SP(regs) += 6; |
651 | } |
652 | IP(regs) = newip; |
653 | regs->pt.cs = newcs; |
654 | CHECK_IF_IN_TRAP; |
655 | if (data32) { |
656 | set_vflags_long(newflags, regs); |
657 | } else { |
658 | set_vflags_short(newflags, regs); |
659 | } |
660 | goto check_vip; |
661 | } |
662 | |
663 | /* cli */ |
664 | case 0xfa: |
665 | IP(regs) = ip; |
666 | clear_IF(regs); |
667 | goto vm86_fault_return; |
668 | |
669 | /* sti */ |
670 | /* |
671 | * Damn. This is incorrect: the 'sti' instruction should actually |
672 | * enable interrupts after the /next/ instruction. Not good. |
673 | * |
674 | * Probably needs some horsing around with the TF flag. Aiee.. |
675 | */ |
676 | case 0xfb: |
677 | IP(regs) = ip; |
678 | set_IF(regs); |
679 | goto check_vip; |
680 | |
681 | default: |
682 | save_v86_state(regs, VM86_UNKNOWN); |
683 | } |
684 | |
685 | return; |
686 | |
687 | check_vip: |
688 | if ((VEFLAGS & (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) == |
689 | (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) { |
690 | save_v86_state(regs, VM86_STI); |
691 | return; |
692 | } |
693 | |
694 | vm86_fault_return: |
695 | if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) { |
696 | save_v86_state(regs, VM86_PICRETURN); |
697 | return; |
698 | } |
699 | if (orig_flags & X86_EFLAGS_TF) |
700 | handle_vm86_trap(regs, 0, X86_TRAP_DB); |
701 | return; |
702 | |
703 | simulate_sigsegv: |
704 | /* FIXME: After a long discussion with Stas we finally |
705 | * agreed, that this is wrong. Here we should |
706 | * really send a SIGSEGV to the user program. |
707 | * But how do we create the correct context? We |
708 | * are inside a general protection fault handler |
709 | * and has just returned from a page fault handler. |
710 | * The correct context for the signal handler |
711 | * should be a mixture of the two, but how do we |
712 | * get the information? [KD] |
713 | */ |
714 | save_v86_state(regs, VM86_UNKNOWN); |
715 | } |
716 | |
717 | /* ---------------- vm86 special IRQ passing stuff ----------------- */ |
718 | |
719 | #define VM86_IRQNAME "vm86irq" |
720 | |
721 | static struct vm86_irqs { |
722 | struct task_struct *tsk; |
723 | int sig; |
724 | } vm86_irqs[16]; |
725 | |
726 | static DEFINE_SPINLOCK(irqbits_lock); |
727 | static int irqbits; |
728 | |
729 | #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ |
730 | | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ |
731 | | (1 << SIGUNUSED)) |
732 | |
733 | static irqreturn_t irq_handler(int intno, void *dev_id) |
734 | { |
735 | int irq_bit; |
736 | unsigned long flags; |
737 | |
738 | spin_lock_irqsave(&irqbits_lock, flags); |
739 | irq_bit = 1 << intno; |
740 | if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) |
741 | goto out; |
742 | irqbits |= irq_bit; |
743 | if (vm86_irqs[intno].sig) |
744 | send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); |
745 | /* |
746 | * IRQ will be re-enabled when user asks for the irq (whether |
747 | * polling or as a result of the signal) |
748 | */ |
749 | disable_irq_nosync(irq: intno); |
750 | spin_unlock_irqrestore(lock: &irqbits_lock, flags); |
751 | return IRQ_HANDLED; |
752 | |
753 | out: |
754 | spin_unlock_irqrestore(lock: &irqbits_lock, flags); |
755 | return IRQ_NONE; |
756 | } |
757 | |
758 | static inline void free_vm86_irq(int irqnumber) |
759 | { |
760 | unsigned long flags; |
761 | |
762 | free_irq(irqnumber, NULL); |
763 | vm86_irqs[irqnumber].tsk = NULL; |
764 | |
765 | spin_lock_irqsave(&irqbits_lock, flags); |
766 | irqbits &= ~(1 << irqnumber); |
767 | spin_unlock_irqrestore(lock: &irqbits_lock, flags); |
768 | } |
769 | |
770 | void release_vm86_irqs(struct task_struct *task) |
771 | { |
772 | int i; |
773 | for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) |
774 | if (vm86_irqs[i].tsk == task) |
775 | free_vm86_irq(i); |
776 | } |
777 | |
778 | static inline int get_and_reset_irq(int irqnumber) |
779 | { |
780 | int bit; |
781 | unsigned long flags; |
782 | int ret = 0; |
783 | |
784 | if (invalid_vm86_irq(irqnumber)) return 0; |
785 | if (vm86_irqs[irqnumber].tsk != current) return 0; |
786 | spin_lock_irqsave(&irqbits_lock, flags); |
787 | bit = irqbits & (1 << irqnumber); |
788 | irqbits &= ~bit; |
789 | if (bit) { |
790 | enable_irq(irq: irqnumber); |
791 | ret = 1; |
792 | } |
793 | |
794 | spin_unlock_irqrestore(lock: &irqbits_lock, flags); |
795 | return ret; |
796 | } |
797 | |
798 | |
799 | static int do_vm86_irq_handling(int subfunction, int irqnumber) |
800 | { |
801 | int ret; |
802 | switch (subfunction) { |
803 | case VM86_GET_AND_RESET_IRQ: { |
804 | return get_and_reset_irq(irqnumber); |
805 | } |
806 | case VM86_GET_IRQ_BITS: { |
807 | return irqbits; |
808 | } |
809 | case VM86_REQUEST_IRQ: { |
810 | int sig = irqnumber >> 8; |
811 | int irq = irqnumber & 255; |
812 | if (!capable(CAP_SYS_ADMIN)) return -EPERM; |
813 | if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; |
814 | if (invalid_vm86_irq(irq)) return -EPERM; |
815 | if (vm86_irqs[irq].tsk) return -EPERM; |
816 | ret = request_irq(irq, handler: &irq_handler, flags: 0, VM86_IRQNAME, NULL); |
817 | if (ret) return ret; |
818 | vm86_irqs[irq].sig = sig; |
819 | vm86_irqs[irq].tsk = current; |
820 | return irq; |
821 | } |
822 | case VM86_FREE_IRQ: { |
823 | if (invalid_vm86_irq(irqnumber)) return -EPERM; |
824 | if (!vm86_irqs[irqnumber].tsk) return 0; |
825 | if (vm86_irqs[irqnumber].tsk != current) return -EPERM; |
826 | free_vm86_irq(irqnumber); |
827 | return 0; |
828 | } |
829 | } |
830 | return -EINVAL; |
831 | } |
832 | |
833 | |