]>
git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - arch/i386/kernel/vm86.c
4 * Copyright (C) 1994 Linus Torvalds
6 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
7 * stack - Manfred Spraul <manfred@colorfullife.com>
9 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle
10 * them correctly. Now the emulation will be in a
11 * consistent state after stackfaults - Kasper Dupont
12 * <kasperd@daimi.au.dk>
14 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
15 * <kasperd@daimi.au.dk>
17 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
18 * caused by Kasper Dupont's changes - Stas Sergeev
20 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
21 * Kasper Dupont <kasperd@daimi.au.dk>
23 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
24 * Kasper Dupont <kasperd@daimi.au.dk>
26 * 9 apr 2002 - Changed stack access macros to jump to a label
27 * instead of returning to userspace. This simplifies
28 * do_int, and is needed by handle_vm6_fault. Kasper
29 * Dupont <kasperd@daimi.au.dk>
33 #include <linux/capability.h>
34 #include <linux/errno.h>
35 #include <linux/interrupt.h>
36 #include <linux/sched.h>
37 #include <linux/kernel.h>
38 #include <linux/signal.h>
39 #include <linux/string.h>
41 #include <linux/smp.h>
42 #include <linux/smp_lock.h>
43 #include <linux/highmem.h>
44 #include <linux/ptrace.h>
45 #include <linux/audit.h>
47 #include <asm/uaccess.h>
49 #include <asm/tlbflush.h>
55 * Interrupt handling is not guaranteed:
56 * - a real x86 will disable all interrupts for one instruction
57 * after a "mov ss,xx" to make stack handling atomic even without
58 * the 'lss' instruction. We can't guarantee this in v86 mode,
59 * as the next instruction might result in a page fault or similar.
60 * - a real x86 will have interrupts disabled for one instruction
61 * past the 'sti' that enables them. We don't bother with all the
64 * Let's hope these problems do not actually matter for anything.
68 #define KVM86 ((struct kernel_vm86_struct *)regs)
69 #define VMPI KVM86->vm86plus
73 * 8- and 16-bit register defines..
75 #define AL(regs) (((unsigned char *)&((regs)->eax))[0])
76 #define AH(regs) (((unsigned char *)&((regs)->eax))[1])
77 #define IP(regs) (*(unsigned short *)&((regs)->eip))
78 #define SP(regs) (*(unsigned short *)&((regs)->esp))
81 * virtual flags (16 and 32-bit versions)
83 #define VFLAGS (*(unsigned short *)&(current->thread.v86flags))
84 #define VEFLAGS (current->thread.v86flags)
86 #define set_flags(X,new,mask) \
87 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
89 #define SAFE_MASK (0xDD5)
90 #define RETURN_MASK (0xDFF)
92 #define VM86_REGS_PART2 orig_eax
93 #define VM86_REGS_SIZE1 \
94 ( (unsigned)( & (((struct kernel_vm86_regs *)0)->VM86_REGS_PART2) ) )
95 #define VM86_REGS_SIZE2 (sizeof(struct kernel_vm86_regs) - VM86_REGS_SIZE1)
97 struct pt_regs
* FASTCALL(save_v86_state(struct kernel_vm86_regs
* regs
));
98 struct pt_regs
* fastcall
save_v86_state(struct kernel_vm86_regs
* regs
)
100 struct tss_struct
*tss
;
105 * This gets called from entry.S with interrupts disabled, but
106 * from process context. Enable interrupts here, before trying
107 * to access user space.
111 if (!current
->thread
.vm86_info
) {
112 printk("no vm86_info: BAD\n");
115 set_flags(regs
->eflags
, VEFLAGS
, VIF_MASK
| current
->thread
.v86mask
);
116 tmp
= copy_to_user(¤t
->thread
.vm86_info
->regs
,regs
, VM86_REGS_SIZE1
);
117 tmp
+= copy_to_user(¤t
->thread
.vm86_info
->regs
.VM86_REGS_PART2
,
118 ®s
->VM86_REGS_PART2
, VM86_REGS_SIZE2
);
119 tmp
+= put_user(current
->thread
.screen_bitmap
,¤t
->thread
.vm86_info
->screen_bitmap
);
121 printk("vm86: could not access userspace vm86_info\n");
125 tss
= &per_cpu(init_tss
, get_cpu());
126 current
->thread
.esp0
= current
->thread
.saved_esp0
;
127 current
->thread
.sysenter_cs
= __KERNEL_CS
;
128 load_esp0(tss
, ¤t
->thread
);
129 current
->thread
.saved_esp0
= 0;
132 loadsegment(fs
, current
->thread
.saved_fs
);
133 loadsegment(gs
, current
->thread
.saved_gs
);
138 static void mark_screen_rdonly(struct mm_struct
*mm
)
147 pgd
= pgd_offset(mm
, 0xA0000);
148 if (pgd_none_or_clear_bad(pgd
))
150 pud
= pud_offset(pgd
, 0xA0000);
151 if (pud_none_or_clear_bad(pud
))
153 pmd
= pmd_offset(pud
, 0xA0000);
154 if (pmd_none_or_clear_bad(pmd
))
156 pte
= pte_offset_map_lock(mm
, pmd
, 0xA0000, &ptl
);
157 for (i
= 0; i
< 32; i
++) {
158 if (pte_present(*pte
))
159 set_pte(pte
, pte_wrprotect(*pte
));
162 pte_unmap_unlock(pte
, ptl
);
169 static int do_vm86_irq_handling(int subfunction
, int irqnumber
);
170 static void do_sys_vm86(struct kernel_vm86_struct
*info
, struct task_struct
*tsk
);
172 asmlinkage
int sys_vm86old(struct pt_regs regs
)
174 struct vm86_struct __user
*v86
= (struct vm86_struct __user
*)regs
.ebx
;
175 struct kernel_vm86_struct info
; /* declare this _on top_,
176 * this avoids wasting of stack space.
177 * This remains on the stack until we
178 * return to 32 bit user space.
180 struct task_struct
*tsk
;
181 int tmp
, ret
= -EPERM
;
184 if (tsk
->thread
.saved_esp0
)
186 tmp
= copy_from_user(&info
, v86
, VM86_REGS_SIZE1
);
187 tmp
+= copy_from_user(&info
.regs
.VM86_REGS_PART2
, &v86
->regs
.VM86_REGS_PART2
,
188 (long)&info
.vm86plus
- (long)&info
.regs
.VM86_REGS_PART2
);
192 memset(&info
.vm86plus
, 0, (int)&info
.regs32
- (int)&info
.vm86plus
);
194 tsk
->thread
.vm86_info
= v86
;
195 do_sys_vm86(&info
, tsk
);
196 ret
= 0; /* we never return here */
202 asmlinkage
int sys_vm86(struct pt_regs regs
)
204 struct kernel_vm86_struct info
; /* declare this _on top_,
205 * this avoids wasting of stack space.
206 * This remains on the stack until we
207 * return to 32 bit user space.
209 struct task_struct
*tsk
;
211 struct vm86plus_struct __user
*v86
;
215 case VM86_REQUEST_IRQ
:
217 case VM86_GET_IRQ_BITS
:
218 case VM86_GET_AND_RESET_IRQ
:
219 ret
= do_vm86_irq_handling(regs
.ebx
, (int)regs
.ecx
);
221 case VM86_PLUS_INSTALL_CHECK
:
222 /* NOTE: on old vm86 stuff this will return the error
223 from access_ok(), because the subfunction is
224 interpreted as (invalid) address to vm86_struct.
225 So the installation check works.
231 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
233 if (tsk
->thread
.saved_esp0
)
235 v86
= (struct vm86plus_struct __user
*)regs
.ecx
;
236 tmp
= copy_from_user(&info
, v86
, VM86_REGS_SIZE1
);
237 tmp
+= copy_from_user(&info
.regs
.VM86_REGS_PART2
, &v86
->regs
.VM86_REGS_PART2
,
238 (long)&info
.regs32
- (long)&info
.regs
.VM86_REGS_PART2
);
243 info
.vm86plus
.is_vm86pus
= 1;
244 tsk
->thread
.vm86_info
= (struct vm86_struct __user
*)v86
;
245 do_sys_vm86(&info
, tsk
);
246 ret
= 0; /* we never return here */
252 static void do_sys_vm86(struct kernel_vm86_struct
*info
, struct task_struct
*tsk
)
254 struct tss_struct
*tss
;
257 * make sure the vm86() system call doesn't try to do anything silly
259 info
->regs
.__null_ds
= 0;
260 info
->regs
.__null_es
= 0;
262 /* we are clearing fs,gs later just before "jmp resume_userspace",
263 * because starting with Linux 2.1.x they aren't no longer saved/restored
267 * The eflags register is also special: we cannot trust that the user
268 * has set it up safely, so this makes sure interrupt etc flags are
269 * inherited from protected mode.
271 VEFLAGS
= info
->regs
.eflags
;
272 info
->regs
.eflags
&= SAFE_MASK
;
273 info
->regs
.eflags
|= info
->regs32
->eflags
& ~SAFE_MASK
;
274 info
->regs
.eflags
|= VM_MASK
;
276 switch (info
->cpu_type
) {
278 tsk
->thread
.v86mask
= 0;
281 tsk
->thread
.v86mask
= NT_MASK
| IOPL_MASK
;
284 tsk
->thread
.v86mask
= AC_MASK
| NT_MASK
| IOPL_MASK
;
287 tsk
->thread
.v86mask
= ID_MASK
| AC_MASK
| NT_MASK
| IOPL_MASK
;
292 * Save old state, set default return value (%eax) to 0
294 info
->regs32
->eax
= 0;
295 tsk
->thread
.saved_esp0
= tsk
->thread
.esp0
;
296 savesegment(fs
, tsk
->thread
.saved_fs
);
297 savesegment(gs
, tsk
->thread
.saved_gs
);
299 tss
= &per_cpu(init_tss
, get_cpu());
300 tsk
->thread
.esp0
= (unsigned long) &info
->VM86_TSS_ESP0
;
302 tsk
->thread
.sysenter_cs
= 0;
303 load_esp0(tss
, &tsk
->thread
);
306 tsk
->thread
.screen_bitmap
= info
->screen_bitmap
;
307 if (info
->flags
& VM86_SCREEN_BITMAP
)
308 mark_screen_rdonly(tsk
->mm
);
309 __asm__
__volatile__("xorl %eax,%eax; movl %eax,%fs; movl %eax,%gs\n\t");
310 __asm__
__volatile__("movl %%eax, %0\n" :"=r"(eax
));
312 /*call audit_syscall_exit since we do not exit via the normal paths */
313 if (unlikely(current
->audit_context
))
314 audit_syscall_exit(AUDITSC_RESULT(eax
), eax
);
316 __asm__
__volatile__(
319 "jmp resume_userspace"
321 :"r" (&info
->regs
), "r" (task_thread_info(tsk
)));
322 /* we never return here */
325 static inline void return_to_32bit(struct kernel_vm86_regs
* regs16
, int retval
)
327 struct pt_regs
* regs32
;
329 regs32
= save_v86_state(regs16
);
330 regs32
->eax
= retval
;
331 __asm__
__volatile__("movl %0,%%esp\n\t"
333 "jmp resume_userspace"
334 : : "r" (regs32
), "r" (current_thread_info()));
337 static inline void set_IF(struct kernel_vm86_regs
* regs
)
340 if (VEFLAGS
& VIP_MASK
)
341 return_to_32bit(regs
, VM86_STI
);
344 static inline void clear_IF(struct kernel_vm86_regs
* regs
)
346 VEFLAGS
&= ~VIF_MASK
;
349 static inline void clear_TF(struct kernel_vm86_regs
* regs
)
351 regs
->eflags
&= ~TF_MASK
;
354 static inline void clear_AC(struct kernel_vm86_regs
* regs
)
356 regs
->eflags
&= ~AC_MASK
;
359 /* It is correct to call set_IF(regs) from the set_vflags_*
360 * functions. However someone forgot to call clear_IF(regs)
361 * in the opposite case.
362 * After the command sequence CLI PUSHF STI POPF you should
363 * end up with interrups disabled, but you ended up with
364 * interrupts enabled.
365 * ( I was testing my own changes, but the only bug I
366 * could find was in a function I had not changed. )
370 static inline void set_vflags_long(unsigned long eflags
, struct kernel_vm86_regs
* regs
)
372 set_flags(VEFLAGS
, eflags
, current
->thread
.v86mask
);
373 set_flags(regs
->eflags
, eflags
, SAFE_MASK
);
374 if (eflags
& IF_MASK
)
380 static inline void set_vflags_short(unsigned short flags
, struct kernel_vm86_regs
* regs
)
382 set_flags(VFLAGS
, flags
, current
->thread
.v86mask
);
383 set_flags(regs
->eflags
, flags
, SAFE_MASK
);
390 static inline unsigned long get_vflags(struct kernel_vm86_regs
* regs
)
392 unsigned long flags
= regs
->eflags
& RETURN_MASK
;
394 if (VEFLAGS
& VIF_MASK
)
397 return flags
| (VEFLAGS
& current
->thread
.v86mask
);
400 static inline int is_revectored(int nr
, struct revectored_struct
* bitmap
)
402 __asm__
__volatile__("btl %2,%1\n\tsbbl %0,%0"
404 :"m" (*bitmap
),"r" (nr
));
408 #define val_byte(val, n) (((__u8 *)&val)[n])
410 #define pushb(base, ptr, val, err_label) \
414 if (put_user(__val, base + ptr) < 0) \
418 #define pushw(base, ptr, val, err_label) \
422 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
425 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
429 #define pushl(base, ptr, val, err_label) \
433 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
436 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
439 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
442 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
446 #define popb(base, ptr, err_label) \
449 if (get_user(__res, base + ptr) < 0) \
455 #define popw(base, ptr, err_label) \
458 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
461 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
467 #define popl(base, ptr, err_label) \
470 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
473 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
476 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
479 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
485 /* There are so many possible reasons for this function to return
486 * VM86_INTx, so adding another doesn't bother me. We can expect
487 * userspace programs to be able to handle it. (Getting a problem
488 * in userspace is always better than an Oops anyway.) [KD]
490 static void do_int(struct kernel_vm86_regs
*regs
, int i
,
491 unsigned char __user
* ssp
, unsigned short sp
)
493 unsigned long __user
*intr_ptr
;
494 unsigned long segoffs
;
496 if (regs
->cs
== BIOSSEG
)
498 if (is_revectored(i
, &KVM86
->int_revectored
))
500 if (i
==0x21 && is_revectored(AH(regs
),&KVM86
->int21_revectored
))
502 intr_ptr
= (unsigned long __user
*) (i
<< 2);
503 if (get_user(segoffs
, intr_ptr
))
505 if ((segoffs
>> 16) == BIOSSEG
)
507 pushw(ssp
, sp
, get_vflags(regs
), cannot_handle
);
508 pushw(ssp
, sp
, regs
->cs
, cannot_handle
);
509 pushw(ssp
, sp
, IP(regs
), cannot_handle
);
510 regs
->cs
= segoffs
>> 16;
512 IP(regs
) = segoffs
& 0xffff;
519 return_to_32bit(regs
, VM86_INTx
+ (i
<< 8));
522 int handle_vm86_trap(struct kernel_vm86_regs
* regs
, long error_code
, int trapno
)
524 if (VMPI
.is_vm86pus
) {
525 if ( (trapno
==3) || (trapno
==1) )
526 return_to_32bit(regs
, VM86_TRAP
+ (trapno
<< 8));
527 do_int(regs
, trapno
, (unsigned char __user
*) (regs
->ss
<< 4), SP(regs
));
531 return 1; /* we let this handle by the calling routine */
532 if (current
->ptrace
& PT_PTRACED
) {
534 spin_lock_irqsave(¤t
->sighand
->siglock
, flags
);
535 sigdelset(¤t
->blocked
, SIGTRAP
);
537 spin_unlock_irqrestore(¤t
->sighand
->siglock
, flags
);
539 send_sig(SIGTRAP
, current
, 1);
540 current
->thread
.trap_no
= trapno
;
541 current
->thread
.error_code
= error_code
;
545 void handle_vm86_fault(struct kernel_vm86_regs
* regs
, long error_code
)
547 unsigned char opcode
;
548 unsigned char __user
*csp
;
549 unsigned char __user
*ssp
;
550 unsigned short ip
, sp
, orig_flags
;
551 int data32
, pref_done
;
553 #define CHECK_IF_IN_TRAP \
554 if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
556 #define VM86_FAULT_RETURN do { \
557 if (VMPI.force_return_for_pic && (VEFLAGS & (IF_MASK | VIF_MASK))) \
558 return_to_32bit(regs, VM86_PICRETURN); \
559 if (orig_flags & TF_MASK) \
560 handle_vm86_trap(regs, 0, 1); \
563 orig_flags
= *(unsigned short *)®s
->eflags
;
565 csp
= (unsigned char __user
*) (regs
->cs
<< 4);
566 ssp
= (unsigned char __user
*) (regs
->ss
<< 4);
573 switch (opcode
= popb(csp
, ip
, simulate_sigsegv
)) {
574 case 0x66: /* 32-bit data */ data32
=1; break;
575 case 0x67: /* 32-bit address */ break;
576 case 0x2e: /* CS */ break;
577 case 0x3e: /* DS */ break;
578 case 0x26: /* ES */ break;
579 case 0x36: /* SS */ break;
580 case 0x65: /* GS */ break;
581 case 0x64: /* FS */ break;
582 case 0xf2: /* repnz */ break;
583 case 0xf3: /* rep */ break;
584 default: pref_done
= 1;
586 } while (!pref_done
);
593 pushl(ssp
, sp
, get_vflags(regs
), simulate_sigsegv
);
596 pushw(ssp
, sp
, get_vflags(regs
), simulate_sigsegv
);
605 unsigned long newflags
;
607 newflags
=popl(ssp
, sp
, simulate_sigsegv
);
610 newflags
= popw(ssp
, sp
, simulate_sigsegv
);
616 set_vflags_long(newflags
, regs
);
618 set_vflags_short(newflags
, regs
);
625 int intno
=popb(csp
, ip
, simulate_sigsegv
);
627 if (VMPI
.vm86dbg_active
) {
628 if ( (1 << (intno
&7)) & VMPI
.vm86dbg_intxxtab
[intno
>> 3] )
629 return_to_32bit(regs
, VM86_INTx
+ (intno
<< 8));
631 do_int(regs
, intno
, ssp
, sp
);
640 unsigned long newflags
;
642 newip
=popl(ssp
, sp
, simulate_sigsegv
);
643 newcs
=popl(ssp
, sp
, simulate_sigsegv
);
644 newflags
=popl(ssp
, sp
, simulate_sigsegv
);
647 newip
= popw(ssp
, sp
, simulate_sigsegv
);
648 newcs
= popw(ssp
, sp
, simulate_sigsegv
);
649 newflags
= popw(ssp
, sp
, simulate_sigsegv
);
656 set_vflags_long(newflags
, regs
);
658 set_vflags_short(newflags
, regs
);
671 * Damn. This is incorrect: the 'sti' instruction should actually
672 * enable interrupts after the /next/ instruction. Not good.
674 * Probably needs some horsing around with the TF flag. Aiee..
682 return_to_32bit(regs
, VM86_UNKNOWN
);
688 /* FIXME: After a long discussion with Stas we finally
689 * agreed, that this is wrong. Here we should
690 * really send a SIGSEGV to the user program.
691 * But how do we create the correct context? We
692 * are inside a general protection fault handler
693 * and has just returned from a page fault handler.
694 * The correct context for the signal handler
695 * should be a mixture of the two, but how do we
696 * get the information? [KD]
698 return_to_32bit(regs
, VM86_UNKNOWN
);
701 /* ---------------- vm86 special IRQ passing stuff ----------------- */
703 #define VM86_IRQNAME "vm86irq"
705 static struct vm86_irqs
{
706 struct task_struct
*tsk
;
710 static DEFINE_SPINLOCK(irqbits_lock
);
713 #define ALLOWED_SIGS ( 1 /* 0 = don't send a signal */ \
714 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
717 static irqreturn_t
irq_handler(int intno
, void *dev_id
, struct pt_regs
* regs
)
722 spin_lock_irqsave(&irqbits_lock
, flags
);
723 irq_bit
= 1 << intno
;
724 if ((irqbits
& irq_bit
) || ! vm86_irqs
[intno
].tsk
)
727 if (vm86_irqs
[intno
].sig
)
728 send_sig(vm86_irqs
[intno
].sig
, vm86_irqs
[intno
].tsk
, 1);
730 * IRQ will be re-enabled when user asks for the irq (whether
731 * polling or as a result of the signal)
733 disable_irq_nosync(intno
);
734 spin_unlock_irqrestore(&irqbits_lock
, flags
);
738 spin_unlock_irqrestore(&irqbits_lock
, flags
);
742 static inline void free_vm86_irq(int irqnumber
)
746 free_irq(irqnumber
, NULL
);
747 vm86_irqs
[irqnumber
].tsk
= NULL
;
749 spin_lock_irqsave(&irqbits_lock
, flags
);
750 irqbits
&= ~(1 << irqnumber
);
751 spin_unlock_irqrestore(&irqbits_lock
, flags
);
754 void release_vm86_irqs(struct task_struct
*task
)
757 for (i
= FIRST_VM86_IRQ
; i
<= LAST_VM86_IRQ
; i
++)
758 if (vm86_irqs
[i
].tsk
== task
)
762 static inline int get_and_reset_irq(int irqnumber
)
768 if (invalid_vm86_irq(irqnumber
)) return 0;
769 if (vm86_irqs
[irqnumber
].tsk
!= current
) return 0;
770 spin_lock_irqsave(&irqbits_lock
, flags
);
771 bit
= irqbits
& (1 << irqnumber
);
774 enable_irq(irqnumber
);
778 spin_unlock_irqrestore(&irqbits_lock
, flags
);
783 static int do_vm86_irq_handling(int subfunction
, int irqnumber
)
786 switch (subfunction
) {
787 case VM86_GET_AND_RESET_IRQ
: {
788 return get_and_reset_irq(irqnumber
);
790 case VM86_GET_IRQ_BITS
: {
793 case VM86_REQUEST_IRQ
: {
794 int sig
= irqnumber
>> 8;
795 int irq
= irqnumber
& 255;
796 if (!capable(CAP_SYS_ADMIN
)) return -EPERM
;
797 if (!((1 << sig
) & ALLOWED_SIGS
)) return -EPERM
;
798 if (invalid_vm86_irq(irq
)) return -EPERM
;
799 if (vm86_irqs
[irq
].tsk
) return -EPERM
;
800 ret
= request_irq(irq
, &irq_handler
, 0, VM86_IRQNAME
, NULL
);
802 vm86_irqs
[irq
].sig
= sig
;
803 vm86_irqs
[irq
].tsk
= current
;
806 case VM86_FREE_IRQ
: {
807 if (invalid_vm86_irq(irqnumber
)) return -EPERM
;
808 if (!vm86_irqs
[irqnumber
].tsk
) return 0;
809 if (vm86_irqs
[irqnumber
].tsk
!= current
) return -EPERM
;
810 free_vm86_irq(irqnumber
);