summaryrefslogtreecommitdiffstats
path: root/sys/kern/subr_trap.c
blob: 9dca842750783bcd98b1e471a03b25d357dfb196 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
/*-
 * Copyright (C) 1994, David Greenman
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the University of Utah, and William Jolitz.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: @(#)trap.c	7.4 (Berkeley) 5/13/91
 *	$Id$
 */

/*
 * 386 Trap and System call handling
 */

#include "opt_ktrace.h"
#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/acct.h>
#include <sys/kernel.h>
#include <sys/syscall.h>
#include <sys/sysent.h>
#include <sys/queue.h>
#include <sys/vmmeter.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_prot.h>
#include <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_extern.h>

#include <sys/user.h>

#include <machine/cpu.h>
#include <machine/md_var.h>
#include <machine/psl.h>
#include <machine/reg.h>
#include <machine/trap.h>
#include <machine/../isa/isa_device.h>

#ifdef POWERFAIL_NMI
#include <sys/syslog.h>
#include <machine/clock.h>
#endif

#include "isa.h"
#include "npx.h"

int (*pmath_emulate) __P((struct trapframe *));

extern void trap __P((struct trapframe frame));
extern int trapwrite __P((unsigned addr));
extern void syscall __P((struct trapframe frame));

static int trap_pfault __P((struct trapframe *, int));
static void trap_fatal __P((struct trapframe *));
void dblfault_handler __P((void));

extern inthand_t IDTVEC(syscall);

#define MAX_TRAP_MSG		28
static char *trap_msg[] = {
	"",					/*  0 unused */
	"privileged instruction fault",		/*  1 T_PRIVINFLT */
	"",					/*  2 unused */
	"breakpoint instruction fault",		/*  3 T_BPTFLT */
	"",					/*  4 unused */
	"",					/*  5 unused */
	"arithmetic trap",			/*  6 T_ARITHTRAP */
	"system forced exception",		/*  7 T_ASTFLT */
	"",					/*  8 unused */
	"general protection fault",		/*  9 T_PROTFLT */
	"trace trap",				/* 10 T_TRCTRAP */
	"",					/* 11 unused */
	"page fault",				/* 12 T_PAGEFLT */
	"",					/* 13 unused */
	"alignment fault",			/* 14 T_ALIGNFLT */
	"",					/* 15 unused */
	"",					/* 16 unused */
	"",					/* 17 unused */
	"integer divide fault",			/* 18 T_DIVIDE */
	"non-maskable interrupt trap",		/* 19 T_NMI */
	"overflow trap",			/* 20 T_OFLOW */
	"FPU bounds check fault",		/* 21 T_BOUND */
	"FPU device not available",		/* 22 T_DNA */
	"double fault",				/* 23 T_DOUBLEFLT */
	"FPU operand fetch fault",		/* 24 T_FPOPFLT */
	"invalid TSS fault",			/* 25 T_TSSFLT */
	"segment not present fault",		/* 26 T_SEGNPFLT */
	"stack fault",				/* 27 T_STKFLT */
	"machine check trap",			/* 28 T_MCHK */
};

static void userret __P((struct proc *p, struct trapframe *frame,
			 u_quad_t oticks));

static inline void
userret(p, frame, oticks)
	struct proc *p;
	struct trapframe *frame;
	u_quad_t oticks;
{
	int sig, s;

	while ((sig = CURSIG(p)) != 0)
		postsig(sig);
	p->p_priority = p->p_usrpri;
	if (want_resched) {
		/*
		 * Since we are curproc, clock will normally just change
		 * our priority without moving us from one queue to another
		 * (since the running process is not on a queue.)
		 * If that happened after we setrunqueue ourselves but before we
		 * mi_switch()'ed, we might not be on the queue indicated by
		 * our priority.
		 */
		s = splhigh();
		setrunqueue(p);
		p->p_stats->p_ru.ru_nivcsw++;
		mi_switch();
		splx(s);
		while ((sig = CURSIG(p)) != 0)
			postsig(sig);
	}
	/*
	 * Charge system time if profiling.
	 */
	if (p->p_flag & P_PROFIL)
		addupc_task(p, frame->tf_eip,
			    (u_int)(p->p_sticks - oticks) * psratio);

	curpriority = p->p_priority;
}

/*
 * Exception, fault, and trap interface to the FreeBSD kernel.
 * This common code is called from assembly language IDT gate entry
 * routines that prepare a suitable stack frame, and restore this
 * frame after the exception has been processed.
 */

void
trap(frame)
	struct trapframe frame;
{
	struct proc *p = curproc;
	u_quad_t sticks = 0;
	int i = 0, ucode = 0, type, code;
#ifdef DEBUG
	u_long eva;
#endif

	type = frame.tf_trapno;
	code = frame.tf_err;

	if (ISPL(frame.tf_cs) == SEL_UPL) {
		/* user trap */

		sticks = p->p_sticks;
		p->p_md.md_regs = (int *)&frame;

		switch (type) {
		case T_PRIVINFLT:	/* privileged instruction fault */
			ucode = type;
			i = SIGILL;
			break;

		case T_BPTFLT:		/* bpt instruction fault */
		case T_TRCTRAP:		/* trace trap */
			frame.tf_eflags &= ~PSL_T;
			i = SIGTRAP;
			break;

		case T_ARITHTRAP:	/* arithmetic trap */
			ucode = code;
			i = SIGFPE;
			break;

		case T_ASTFLT:		/* Allow process switch */
			astoff();
			cnt.v_soft++;
			if (p->p_flag & P_OWEUPC) {
				p->p_flag &= ~P_OWEUPC;
				addupc_task(p, p->p_stats->p_prof.pr_addr,
					    p->p_stats->p_prof.pr_ticks);
			}
			goto out;

		case T_PROTFLT:		/* general protection fault */
		case T_SEGNPFLT:	/* segment not present fault */
		case T_STKFLT:		/* stack fault */
		case T_TSSFLT:		/* invalid TSS fault */
		case T_DOUBLEFLT:	/* double fault */
		default:
			ucode = code + BUS_SEGM_FAULT ;
			i = SIGBUS;
			break;

		case T_PAGEFLT:		/* page fault */
			i = trap_pfault(&frame, TRUE);
			if (i == -1)
				return;
			if (i == 0)
				goto out;

			ucode = T_PAGEFLT;
			break;

		case T_DIVIDE:		/* integer divide fault */
			ucode = FPE_INTDIV_TRAP;
			i = SIGFPE;
			break;

#if NISA > 0
		case T_NMI:
#ifdef POWERFAIL_NMI
			goto handle_powerfail;
#else /* !POWERFAIL_NMI */
#ifdef DDB
			/* NMI can be hooked up to a pushbutton for debugging */
			printf ("NMI ... going to debugger\n");
			if (kdb_trap (type, 0, &frame))
				return;
#endif /* DDB */
			/* machine/parity/power fail/"kitchen sink" faults */
			if (isa_nmi(code) == 0) return;
			panic("NMI indicates hardware failure");
#endif /* POWERFAIL_NMI */
#endif /* NISA > 0 */

		case T_OFLOW:		/* integer overflow fault */
			ucode = FPE_INTOVF_TRAP;
			i = SIGFPE;
			break;

		case T_BOUND:		/* bounds check fault */
			ucode = FPE_SUBRNG_TRAP;
			i = SIGFPE;
			break;

		case T_DNA:
#if NNPX > 0
			/* if a transparent fault (due to context switch "late") */
			if (npxdna())
				return;
#endif
			if (!pmath_emulate) {
				i = SIGFPE;
				ucode = FPE_FPU_NP_TRAP;
				break;
			}
			i = (*pmath_emulate)(&frame);
			if (i == 0) {
				if (!(frame.tf_eflags & PSL_T))
					return;
				frame.tf_eflags &= ~PSL_T;
				i = SIGTRAP;
			}
			/* else ucode = emulator_only_knows() XXX */
			break;

		case T_FPOPFLT:		/* FPU operand fetch fault */
			ucode = T_FPOPFLT;
			i = SIGILL;
			break;
		}
	} else {
		/* kernel trap */

		switch (type) {
		case T_PAGEFLT:			/* page fault */
			(void) trap_pfault(&frame, FALSE);
			return;

		case T_DNA:
#if NNPX > 0
			/*
			 * The kernel is apparently using npx for copying.
			 * XXX this should be fatal unless the kernel has
			 * registered such use.
			 */
			if (npxdna())
				return;
#endif
			break;

		case T_PROTFLT:		/* general protection fault */
		case T_SEGNPFLT:	/* segment not present fault */
			/*
			 * Invalid segment selectors and out of bounds
			 * %eip's and %esp's can be set up in user mode.
			 * This causes a fault in kernel mode when the
			 * kernel tries to return to user mode.  We want
			 * to get this fault so that we can fix the
			 * problem here and not have to check all the
			 * selectors and pointers when the user changes
			 * them.
			 */
#define	MAYBE_DORETI_FAULT(where, whereto)				\
	do {								\
		if (frame.tf_eip == (int)where) {			\
			frame.tf_eip = (int)whereto;			\
			return;						\
		}							\
	} while (0)

			if (intr_nesting_level == 0) {
				MAYBE_DORETI_FAULT(doreti_iret,
						   doreti_iret_fault);
				MAYBE_DORETI_FAULT(doreti_popl_ds,
						   doreti_popl_ds_fault);
				MAYBE_DORETI_FAULT(doreti_popl_es,
						   doreti_popl_es_fault);
				if (curpcb && curpcb->pcb_onfault) {
					frame.tf_eip = (int)curpcb->pcb_onfault;
					return;
				}
			}
			break;

		case T_TSSFLT:
			/*
			 * PSL_NT can be set in user mode and isn't cleared
			 * automatically when the kernel is entered.  This
			 * causes a TSS fault when the kernel attempts to
			 * `iret' because the TSS link is uninitialized.  We
			 * want to get this fault so that we can fix the
			 * problem here and not every time the kernel is
			 * entered.
			 */
			if (frame.tf_eflags & PSL_NT) {
				frame.tf_eflags &= ~PSL_NT;
				return;
			}
			break;

		case T_TRCTRAP:	 /* trace trap */
			if (frame.tf_eip == (int)IDTVEC(syscall)) {
				/*
				 * We've just entered system mode via the
				 * syscall lcall.  Continue single stepping
				 * silently until the syscall handler has
				 * saved the flags.
				 */
				return;
			}
			if (frame.tf_eip == (int)IDTVEC(syscall) + 1) {
				/*
				 * The syscall handler has now saved the
				 * flags.  Stop single stepping it.
				 */
				frame.tf_eflags &= ~PSL_T;
				return;
			}
			/*
			 * Fall through.
			 */
		case T_BPTFLT:
			/*
			 * If DDB is enabled, let it handle the debugger trap.
			 * Otherwise, debugger traps "can't happen".
			 */
#ifdef DDB
			if (kdb_trap (type, 0, &frame))
				return;
#endif
			break;

#if NISA > 0
		case T_NMI:
#ifdef POWERFAIL_NMI
#ifndef TIMER_FREQ
#  define TIMER_FREQ 1193182
#endif
	handle_powerfail:
		{
		  static unsigned lastalert = 0;

		  if(time.tv_sec - lastalert > 10)
		    {
		      log(LOG_WARNING, "NMI: power fail\n");
		      sysbeep(TIMER_FREQ/880, hz);
		      lastalert = time.tv_sec;
		    }
		  return;
		}
#else /* !POWERFAIL_NMI */
#ifdef DDB
			/* NMI can be hooked up to a pushbutton for debugging */
			printf ("NMI ... going to debugger\n");
			if (kdb_trap (type, 0, &frame))
				return;
#endif /* DDB */
			/* machine/parity/power fail/"kitchen sink" faults */
			if (isa_nmi(code) == 0) return;
			/* FALL THROUGH */
#endif /* POWERFAIL_NMI */
#endif /* NISA > 0 */
		}

		trap_fatal(&frame);
		return;
	}

	trapsignal(p, i, ucode);

#ifdef DEBUG
	eva = rcr2();
	if (type <= MAX_TRAP_MSG) {
		uprintf("fatal process exception: %s",
			trap_msg[type]);
		if ((type == T_PAGEFLT) || (type == T_PROTFLT))
			uprintf(", fault VA = 0x%x", eva);
		uprintf("\n");
	}
#endif

out:
	userret(p, &frame, sticks);
}

#ifdef notyet
/*
 * This version doesn't allow a page fault to user space while
 * in the kernel. The rest of the kernel needs to be made "safe"
 * before this can be used. I think the only things remaining
 * to be made safe are the iBCS2 code and the process tracing/
 * debugging code.
 */
static int
trap_pfault(frame, usermode)
	struct trapframe *frame;
	int usermode;
{
	vm_offset_t va;
	struct vmspace *vm = NULL;
	vm_map_t map = 0;
	int rv = 0;
	vm_prot_t ftype;
	int eva;
	struct proc *p = curproc;

	if (frame->tf_err & PGEX_W)
		ftype = VM_PROT_READ | VM_PROT_WRITE;
	else
		ftype = VM_PROT_READ;

	eva = rcr2();
	va = trunc_page((vm_offset_t)eva);

	if (va < VM_MIN_KERNEL_ADDRESS) {
		vm_offset_t v;
		vm_page_t mpte;

		if (p == NULL ||
		    (!usermode && va < VM_MAXUSER_ADDRESS &&
		     (intr_nesting_level != 0 || curpcb == NULL ||
		      curpcb->pcb_onfault == NULL))) {
			trap_fatal(frame);
			return (-1);
		}

		/*
		 * This is a fault on non-kernel virtual memory.
		 * vm is initialized above to NULL. If curproc is NULL
		 * or curproc->p_vmspace is NULL the fault is fatal.
		 */
		vm = p->p_vmspace;
		if (vm == NULL)
			goto nogo;

		map = &vm->vm_map;

		/*
		 * Keep swapout from messing with us during this
		 *	critical time.
		 */
		++p->p_lock;

		/*
		 * Grow the stack if necessary
		 */
		if ((caddr_t)va > vm->vm_maxsaddr
		    && (caddr_t)va < (caddr_t)USRSTACK) {
			if (!grow(p, va)) {
				rv = KERN_FAILURE;
				--p->p_lock;
				goto nogo;
			}
		}

		/* Fault in the user page: */
		rv = vm_fault(map, va, ftype, FALSE);

		--p->p_lock;
	} else {
		/*
		 * Don't allow user-mode faults in kernel address space.
		 */
		if (usermode)
			goto nogo;

		/*
		 * Since we know that kernel virtual address addresses
		 * always have pte pages mapped, we just have to fault
		 * the page.
		 */
		rv = vm_fault(kernel_map, va, ftype, FALSE);
	}

	if (rv == KERN_SUCCESS)
		return (0);
nogo:
	if (!usermode) {
		if (intr_nesting_level == 0 && curpcb && curpcb->pcb_onfault) {
			frame->tf_eip = (int)curpcb->pcb_onfault;
			return (0);
		}
		trap_fatal(frame);
		return (-1);
	}

	/* kludge to pass faulting virtual address to sendsig */
	frame->tf_err = eva;

	return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
}
#endif

int
trap_pfault(frame, usermode)
	struct trapframe *frame;
	int usermode;
{
	vm_offset_t va;
	struct vmspace *vm = NULL;
	vm_map_t map = 0;
	int rv = 0;
	vm_prot_t ftype;
	int eva;
	struct proc *p = curproc;

	eva = rcr2();
	va = trunc_page((vm_offset_t)eva);

	if (va >= KERNBASE) {
		/*
		 * Don't allow user-mode faults in kernel address space.
		 */
		if (usermode)
			goto nogo;

		map = kernel_map;
	} else {
		/*
		 * This is a fault on non-kernel virtual memory.
		 * vm is initialized above to NULL. If curproc is NULL
		 * or curproc->p_vmspace is NULL the fault is fatal.
		 */
		if (p != NULL)
			vm = p->p_vmspace;

		if (vm == NULL)
			goto nogo;

		map = &vm->vm_map;
	}

	if (frame->tf_err & PGEX_W)
		ftype = VM_PROT_READ | VM_PROT_WRITE;
	else
		ftype = VM_PROT_READ;

	if (map != kernel_map) {
		/*
		 * Keep swapout from messing with us during this
		 *	critical time.
		 */
		++p->p_lock;

		/*
		 * Grow the stack if necessary
		 */
		if ((caddr_t)va > vm->vm_maxsaddr
		    && (caddr_t)va < (caddr_t)USRSTACK) {
			if (!grow(p, va)) {
				rv = KERN_FAILURE;
				--p->p_lock;
				goto nogo;
			}
		}

		/* Fault in the user page: */
		rv = vm_fault(map, va, ftype, FALSE);

		--p->p_lock;
	} else {
		/*
		 * Since we know that kernel virtual address addresses
		 * always have pte pages mapped, we just have to fault
		 * the page.
		 */
		rv = vm_fault(map, va, ftype, FALSE);
	}

	if (rv == KERN_SUCCESS)
		return (0);
nogo:
	if (!usermode) {
		if (intr_nesting_level == 0 && curpcb && curpcb->pcb_onfault) {
			frame->tf_eip = (int)curpcb->pcb_onfault;
			return (0);
		}
		trap_fatal(frame);
		return (-1);
	}

	/* kludge to pass faulting virtual address to sendsig */
	frame->tf_err = eva;

	return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
}

static void
trap_fatal(frame)
	struct trapframe *frame;
{
	int code, type, eva, ss, esp;
	struct soft_segment_descriptor softseg;

	code = frame->tf_err;
	type = frame->tf_trapno;
	eva = rcr2();
	sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg);

	if (type <= MAX_TRAP_MSG)
		printf("\n\nFatal trap %d: %s while in %s mode\n",
			type, trap_msg[type],
			ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel");
	if (type == T_PAGEFLT) {
		printf("fault virtual address	= 0x%x\n", eva);
		printf("fault code		= %s %s, %s\n",
			code & PGEX_U ? "user" : "supervisor",
			code & PGEX_W ? "write" : "read",
			code & PGEX_P ? "protection violation" : "page not present");
	}
	printf("instruction pointer	= 0x%x:0x%x\n",
	       frame->tf_cs & 0xffff, frame->tf_eip);
	if (ISPL(frame->tf_cs) == SEL_UPL) {
		ss = frame->tf_ss & 0xffff;
		esp = frame->tf_esp;
	} else {
		ss = GSEL(GDATA_SEL, SEL_KPL);
		esp = (int)&frame->tf_esp;
	}
	printf("stack pointer	        = 0x%x:0x%x\n", ss, esp);
	printf("frame pointer	        = 0x%x:0x%x\n", ss, frame->tf_ebp);
	printf("code segment		= base 0x%x, limit 0x%x, type 0x%x\n",
	       softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type);
	printf("			= DPL %d, pres %d, def32 %d, gran %d\n",
	       softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32,
	       softseg.ssd_gran);
	printf("processor eflags	= ");
	if (frame->tf_eflags & PSL_T)
		printf("trace trap, ");
	if (frame->tf_eflags & PSL_I)
		printf("interrupt enabled, ");
	if (frame->tf_eflags & PSL_NT)
		printf("nested task, ");
	if (frame->tf_eflags & PSL_RF)
		printf("resume, ");
	if (frame->tf_eflags & PSL_VM)
		printf("vm86, ");
	printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12);
	printf("current process		= ");
	if (curproc) {
		printf("%lu (%s)\n",
		    (u_long)curproc->p_pid, curproc->p_comm ?
		    curproc->p_comm : "");
	} else {
		printf("Idle\n");
	}
	printf("interrupt mask		= ");
	if ((cpl & net_imask) == net_imask)
		printf("net ");
	if ((cpl & tty_imask) == tty_imask)
		printf("tty ");
	if ((cpl & bio_imask) == bio_imask)
		printf("bio ");
	if (cpl == 0)
		printf("none");
	printf("\n");

#ifdef KDB
	if (kdb_trap(&psl))
		return;
#endif
#ifdef DDB
	if (kdb_trap (type, 0, frame))
		return;
#endif
	if (type <= MAX_TRAP_MSG)
		panic(trap_msg[type]);
	else
		panic("unknown/reserved trap");
}

/*
 * Double fault handler. Called when a fault occurs while writing
 * a frame for a trap/exception onto the stack. This usually occurs
 * when the stack overflows (such is the case with infinite recursion,
 * for example).
 *
 * XXX Note that the current PTD gets replaced by IdlePTD when the
 * task switch occurs. This means that the stack that was active at
 * the time of the double fault is not available at <kstack> unless
 * the machine was idle when the double fault occurred. The downside
 * of this is that "trace <ebp>" in ddb won't work.
 */
void
dblfault_handler()
{
	struct pcb *pcb = curpcb;

	if (pcb != NULL) {
		printf("\nFatal double fault:\n");
		printf("eip = 0x%x\n", pcb->pcb_tss.tss_eip);
		printf("esp = 0x%x\n", pcb->pcb_tss.tss_esp);
		printf("ebp = 0x%x\n", pcb->pcb_tss.tss_ebp);
	}

	panic("double fault");
}

/*
 * Compensate for 386 brain damage (missing URKR).
 * This is a little simpler than the pagefault handler in trap() because
 * it the page tables have already been faulted in and high addresses
 * are thrown out early for other reasons.
 */
int trapwrite(addr)
	unsigned addr;
{
	struct proc *p;
	vm_offset_t va;
	struct vmspace *vm;
	int rv;

	va = trunc_page((vm_offset_t)addr);
	/*
	 * XXX - MAX is END.  Changed > to >= for temp. fix.
	 */
	if (va >= VM_MAXUSER_ADDRESS)
		return (1);

	p = curproc;
	vm = p->p_vmspace;

	++p->p_lock;

	if ((caddr_t)va >= vm->vm_maxsaddr
	    && (caddr_t)va < (caddr_t)USRSTACK) {
		if (!grow(p, va)) {
			--p->p_lock;
			return (1);
		}
	}

	/*
	 * fault the data page
	 */
	rv = vm_fault(&vm->vm_map, va, VM_PROT_READ|VM_PROT_WRITE, FALSE);

	--p->p_lock;

	if (rv != KERN_SUCCESS)
		return 1;

	return (0);
}

/*
 * System call request from POSIX system call gate interface to kernel.
 * Like trap(), argument is call by reference.
 */
void
syscall(frame)
	struct trapframe frame;
{
	caddr_t params;
	int i;
	struct sysent *callp;
	struct proc *p = curproc;
	u_quad_t sticks;
	int error;
	int args[8], rval[2];
	u_int code;

	sticks = p->p_sticks;
	if (ISPL(frame.tf_cs) != SEL_UPL)
		panic("syscall");

	p->p_md.md_regs = (int *)&frame;
	params = (caddr_t)frame.tf_esp + sizeof(int);
	code = frame.tf_eax;
	if (p->p_sysent->sv_prepsyscall) {
		(*p->p_sysent->sv_prepsyscall)(&frame, args, &code, &params);
	} else {
		/*
		 * Need to check if this is a 32 bit or 64 bit syscall.
		 */
		if (code == SYS_syscall) {
			/*
			 * Code is first argument, followed by actual args.
			 */
			code = fuword(params);
			params += sizeof(int);
		} else if (code == SYS___syscall) {
			/*
			 * Like syscall, but code is a quad, so as to maintain
			 * quad alignment for the rest of the arguments.
			 */
			code = fuword(params);
			params += sizeof(quad_t);
		}
	}

 	if (p->p_sysent->sv_mask)
 		code &= p->p_sysent->sv_mask;

 	if (code >= p->p_sysent->sv_size)
 		callp = &p->p_sysent->sv_table[0];
  	else
 		callp = &p->p_sysent->sv_table[code];

	if (params && (i = callp->sy_narg * sizeof(int)) &&
	    (error = copyin(params, (caddr_t)args, (u_int)i))) {
#ifdef KTRACE
		if (KTRPOINT(p, KTR_SYSCALL))
			ktrsyscall(p->p_tracep, code, callp->sy_narg, args);
#endif
		goto bad;
	}
#ifdef KTRACE
	if (KTRPOINT(p, KTR_SYSCALL))
		ktrsyscall(p->p_tracep, code, callp->sy_narg, args);
#endif
	rval[0] = 0;
	rval[1] = frame.tf_edx;

	error = (*callp->sy_call)(p, args, rval);

	switch (error) {

	case 0:
		/*
		 * Reinitialize proc pointer `p' as it may be different
		 * if this is a child returning from fork syscall.
		 */
		p = curproc;
		frame.tf_eax = rval[0];
		frame.tf_edx = rval[1];
		frame.tf_eflags &= ~PSL_C;
		break;

	case ERESTART:
		/*
		 * Reconstruct pc, assuming lcall $X,y is 7 bytes,
		 * int 0x80 is 2 bytes. We saved this in tf_err.
		 */
		frame.tf_eip -= frame.tf_err;
		break;

	case EJUSTRETURN:
		break;

	default:
bad:
 		if (p->p_sysent->sv_errsize)
 			if (error >= p->p_sysent->sv_errsize)
  				error = -1;	/* XXX */
   			else
  				error = p->p_sysent->sv_errtbl[error];
		frame.tf_eax = error;
		frame.tf_eflags |= PSL_C;
		break;
	}

	if (frame.tf_eflags & PSL_T) {
		/* Traced syscall. */
		frame.tf_eflags &= ~PSL_T;
		trapsignal(p, SIGTRAP, 0);
	}

	userret(p, &frame, sticks);

#ifdef KTRACE
	if (KTRPOINT(p, KTR_SYSRET))
		ktrsysret(p->p_tracep, code, error, rval[0]);
#endif
}
OpenPOWER on IntegriCloud