1 /*-
2 * Copyright (C) 1994, David Greenman
3 * Copyright (c) 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * the University of Utah, and William Jolitz.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by the University of
20 * California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
38 */
39
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD: stable/10/sys/i386/i386/trap.c 333370 2018-05-08 17:05:39Z emaste $");
42
43 /*
44 * 386 Trap and System call handling
45 */
46
47 #include "opt_clock.h"
48 #include "opt_cpu.h"
49 #include "opt_hwpmc_hooks.h"
50 #include "opt_isa.h"
51 #include "opt_kdb.h"
52 #include "opt_kdtrace.h"
53 #include "opt_npx.h"
54 #include "opt_trap.h"
55
56 #include <sys/param.h>
57 #include <sys/bus.h>
58 #include <sys/systm.h>
59 #include <sys/proc.h>
60 #include <sys/pioctl.h>
61 #include <sys/ptrace.h>
62 #include <sys/kdb.h>
63 #include <sys/kernel.h>
64 #include <sys/ktr.h>
65 #include <sys/lock.h>
66 #include <sys/mutex.h>
67 #include <sys/resourcevar.h>
68 #include <sys/signalvar.h>
69 #include <sys/syscall.h>
70 #include <sys/sysctl.h>
71 #include <sys/sysent.h>
72 #include <sys/uio.h>
73 #include <sys/vmmeter.h>
74 #ifdef HWPMC_HOOKS
75 #include <sys/pmckern.h>
76 PMC_SOFT_DEFINE( , , page_fault, all);
77 PMC_SOFT_DEFINE( , , page_fault, read);
78 PMC_SOFT_DEFINE( , , page_fault, write);
79 #endif
80 #include <security/audit/audit.h>
81
82 #include <vm/vm.h>
83 #include <vm/vm_param.h>
84 #include <vm/pmap.h>
85 #include <vm/vm_kern.h>
86 #include <vm/vm_map.h>
87 #include <vm/vm_page.h>
88 #include <vm/vm_extern.h>
89
90 #include <machine/cpu.h>
91 #include <machine/intr_machdep.h>
92 #include <x86/mca.h>
93 #include <machine/md_var.h>
94 #include <machine/pcb.h>
95 #ifdef SMP
96 #include <machine/smp.h>
97 #endif
98 #include <machine/tss.h>
99 #include <machine/vm86.h>
100
101 #ifdef POWERFAIL_NMI
102 #include <sys/syslog.h>
103 #include <machine/clock.h>
104 #endif
105
106 #ifdef KDTRACE_HOOKS
107 #include <sys/dtrace_bsd.h>
108 #endif
109
110 extern void trap(struct trapframe *frame);
111 extern void syscall(struct trapframe *frame);
112
113 static int trap_pfault(struct trapframe *, int, vm_offset_t);
114 static void trap_fatal(struct trapframe *, vm_offset_t);
115 void dblfault_handler(void);
116
117 extern inthand_t IDTVEC(lcall_syscall);
118
119 extern inthand_t IDTVEC(bpt), IDTVEC(dbg), IDTVEC(int0x80_syscall);
120
121 #define MAX_TRAP_MSG 32
122 static char *trap_msg[] = {
123 "", /* 0 unused */
124 "privileged instruction fault", /* 1 T_PRIVINFLT */
125 "", /* 2 unused */
126 "breakpoint instruction fault", /* 3 T_BPTFLT */
127 "", /* 4 unused */
128 "", /* 5 unused */
129 "arithmetic trap", /* 6 T_ARITHTRAP */
130 "", /* 7 unused */
131 "", /* 8 unused */
132 "general protection fault", /* 9 T_PROTFLT */
133 "trace trap", /* 10 T_TRCTRAP */
134 "", /* 11 unused */
135 "page fault", /* 12 T_PAGEFLT */
136 "", /* 13 unused */
137 "alignment fault", /* 14 T_ALIGNFLT */
138 "", /* 15 unused */
139 "", /* 16 unused */
140 "", /* 17 unused */
141 "integer divide fault", /* 18 T_DIVIDE */
142 "non-maskable interrupt trap", /* 19 T_NMI */
143 "overflow trap", /* 20 T_OFLOW */
144 "FPU bounds check fault", /* 21 T_BOUND */
145 "FPU device not available", /* 22 T_DNA */
146 "double fault", /* 23 T_DOUBLEFLT */
147 "FPU operand fetch fault", /* 24 T_FPOPFLT */
148 "invalid TSS fault", /* 25 T_TSSFLT */
149 "segment not present fault", /* 26 T_SEGNPFLT */
150 "stack fault", /* 27 T_STKFLT */
151 "machine check trap", /* 28 T_MCHK */
152 "SIMD floating-point exception", /* 29 T_XMMFLT */
153 "reserved (unknown) fault", /* 30 T_RESERVED */
154 "", /* 31 unused (reserved) */
155 "DTrace pid return trap", /* 32 T_DTRACE_RET */
156 };
157
158 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
159 int has_f00f_bug = 0; /* Initialized so that it can be patched. */
160 #endif
161
162 #ifdef KDB
163 static int kdb_on_nmi = 1;
164 SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RW,
165 &kdb_on_nmi, 0, "Go to KDB on NMI");
166 TUNABLE_INT("machdep.kdb_on_nmi", &kdb_on_nmi);
167 #endif
168 static int panic_on_nmi = 1;
169 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW,
170 &panic_on_nmi, 0, "Panic on NMI");
171 TUNABLE_INT("machdep.panic_on_nmi", &panic_on_nmi);
172 static int prot_fault_translation = 0;
173 SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RW,
174 &prot_fault_translation, 0, "Select signal to deliver on protection fault");
175 static int uprintf_signal;
176 SYSCTL_INT(_machdep, OID_AUTO, uprintf_signal, CTLFLAG_RW,
177 &uprintf_signal, 0,
178 "Print debugging information on trap signal to ctty");
179
180 /*
181 * Exception, fault, and trap interface to the FreeBSD kernel.
182 * This common code is called from assembly language IDT gate entry
183 * routines that prepare a suitable stack frame, and restore this
184 * frame after the exception has been processed.
185 */
186
187 void
trap(struct trapframe * frame)188 trap(struct trapframe *frame)
189 {
190 #ifdef KDTRACE_HOOKS
191 struct reg regs;
192 #endif
193 struct thread *td = curthread;
194 struct proc *p = td->td_proc;
195 int i = 0, ucode = 0, code;
196 u_int type;
197 register_t addr = 0;
198 vm_offset_t eva;
199 ksiginfo_t ksi;
200 #ifdef POWERFAIL_NMI
201 static int lastalert = 0;
202 #endif
203
204 PCPU_INC(cnt.v_trap);
205 type = frame->tf_trapno;
206
207 #ifdef SMP
208 /* Handler for NMI IPIs used for stopping CPUs. */
209 if (type == T_NMI) {
210 if (ipi_nmi_handler() == 0)
211 goto out;
212 }
213 #endif /* SMP */
214
215 #ifdef KDB
216 if (kdb_active) {
217 kdb_reenter();
218 goto out;
219 }
220 #endif
221
222 if (type == T_RESERVED) {
223 trap_fatal(frame, 0);
224 goto out;
225 }
226
227 #ifdef HWPMC_HOOKS
228 /*
229 * CPU PMCs interrupt using an NMI so we check for that first.
230 * If the HWPMC module is active, 'pmc_hook' will point to
231 * the function to be called. A return value of '1' from the
232 * hook means that the NMI was handled by it and that we can
233 * return immediately.
234 */
235 if (type == T_NMI && pmc_intr &&
236 (*pmc_intr)(PCPU_GET(cpuid), frame))
237 goto out;
238 #endif
239
240 if (type == T_MCHK) {
241 mca_intr();
242 goto out;
243 }
244
245 #ifdef KDTRACE_HOOKS
246 /*
247 * A trap can occur while DTrace executes a probe. Before
248 * executing the probe, DTrace blocks re-scheduling and sets
249 * a flag in its per-cpu flags to indicate that it doesn't
250 * want to fault. On returning from the probe, the no-fault
251 * flag is cleared and finally re-scheduling is enabled.
252 */
253 if ((type == T_PROTFLT || type == T_PAGEFLT) &&
254 dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, type))
255 goto out;
256 #endif
257
258 if ((frame->tf_eflags & PSL_I) == 0) {
259 /*
260 * Buggy application or kernel code has disabled
261 * interrupts and then trapped. Enabling interrupts
262 * now is wrong, but it is better than running with
263 * interrupts disabled until they are accidentally
264 * enabled later.
265 */
266 if (ISPL(frame->tf_cs) == SEL_UPL || (frame->tf_eflags & PSL_VM))
267 uprintf(
268 "pid %ld (%s): trap %d with interrupts disabled\n",
269 (long)curproc->p_pid, curthread->td_name, type);
270 else if (type != T_NMI && type != T_BPTFLT &&
271 type != T_TRCTRAP &&
272 frame->tf_eip != (int)cpu_switch_load_gs) {
273 /*
274 * XXX not quite right, since this may be for a
275 * multiple fault in user mode.
276 */
277 printf("kernel trap %d with interrupts disabled\n",
278 type);
279 /*
280 * Page faults need interrupts disabled until later,
281 * and we shouldn't enable interrupts while holding
282 * a spin lock.
283 */
284 if (type != T_PAGEFLT &&
285 td->td_md.md_spinlock_count == 0)
286 enable_intr();
287 }
288 }
289 eva = 0;
290 code = frame->tf_err;
291 if (type == T_PAGEFLT) {
292 /*
293 * For some Cyrix CPUs, %cr2 is clobbered by
294 * interrupts. This problem is worked around by using
295 * an interrupt gate for the pagefault handler. We
296 * are finally ready to read %cr2 and conditionally
297 * reenable interrupts. If we hold a spin lock, then
298 * we must not reenable interrupts. This might be a
299 * spurious page fault.
300 */
301 eva = rcr2();
302 if (td->td_md.md_spinlock_count == 0)
303 enable_intr();
304 }
305
306 if ((ISPL(frame->tf_cs) == SEL_UPL) ||
307 ((frame->tf_eflags & PSL_VM) &&
308 !(curpcb->pcb_flags & PCB_VM86CALL))) {
309 /* user trap */
310
311 td->td_pticks = 0;
312 td->td_frame = frame;
313 addr = frame->tf_eip;
314 if (td->td_ucred != p->p_ucred)
315 cred_update_thread(td);
316
317 switch (type) {
318 case T_PRIVINFLT: /* privileged instruction fault */
319 i = SIGILL;
320 ucode = ILL_PRVOPC;
321 break;
322
323 case T_BPTFLT: /* bpt instruction fault */
324 case T_TRCTRAP: /* trace trap */
325 enable_intr();
326 #ifdef KDTRACE_HOOKS
327 if (type == T_BPTFLT) {
328 fill_frame_regs(frame, ®s);
329 if (dtrace_pid_probe_ptr != NULL &&
330 dtrace_pid_probe_ptr(®s) == 0)
331 goto out;
332 }
333 #endif
334 frame->tf_eflags &= ~PSL_T;
335 i = SIGTRAP;
336 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT);
337 break;
338
339 case T_ARITHTRAP: /* arithmetic trap */
340 #ifdef DEV_NPX
341 ucode = npxtrap_x87();
342 if (ucode == -1)
343 goto userout;
344 #else
345 ucode = 0;
346 #endif
347 i = SIGFPE;
348 break;
349
350 /*
351 * The following two traps can happen in
352 * vm86 mode, and, if so, we want to handle
353 * them specially.
354 */
355 case T_PROTFLT: /* general protection fault */
356 case T_STKFLT: /* stack fault */
357 if (frame->tf_eflags & PSL_VM) {
358 i = vm86_emulate((struct vm86frame *)frame);
359 if (i == 0)
360 goto user;
361 break;
362 }
363 i = SIGBUS;
364 ucode = (type == T_PROTFLT) ? BUS_OBJERR : BUS_ADRERR;
365 break;
366 case T_SEGNPFLT: /* segment not present fault */
367 i = SIGBUS;
368 ucode = BUS_ADRERR;
369 break;
370 case T_TSSFLT: /* invalid TSS fault */
371 i = SIGBUS;
372 ucode = BUS_OBJERR;
373 break;
374 case T_ALIGNFLT:
375 i = SIGBUS;
376 ucode = BUS_ADRALN;
377 break;
378 case T_DOUBLEFLT: /* double fault */
379 default:
380 i = SIGBUS;
381 ucode = BUS_OBJERR;
382 break;
383
384 case T_PAGEFLT: /* page fault */
385
386 i = trap_pfault(frame, TRUE, eva);
387 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
388 if (i == -2) {
389 /*
390 * The f00f hack workaround has triggered, so
391 * treat the fault as an illegal instruction
392 * (T_PRIVINFLT) instead of a page fault.
393 */
394 type = frame->tf_trapno = T_PRIVINFLT;
395
396 /* Proceed as in that case. */
397 ucode = ILL_PRVOPC;
398 i = SIGILL;
399 break;
400 }
401 #endif
402 if (i == -1)
403 goto userout;
404 if (i == 0)
405 goto user;
406
407 if (i == SIGSEGV)
408 ucode = SEGV_MAPERR;
409 else {
410 if (prot_fault_translation == 0) {
411 /*
412 * Autodetect.
413 * This check also covers the images
414 * without the ABI-tag ELF note.
415 */
416 if (SV_CURPROC_ABI() == SV_ABI_FREEBSD
417 && p->p_osrel >= P_OSREL_SIGSEGV) {
418 i = SIGSEGV;
419 ucode = SEGV_ACCERR;
420 } else {
421 i = SIGBUS;
422 ucode = BUS_PAGE_FAULT;
423 }
424 } else if (prot_fault_translation == 1) {
425 /*
426 * Always compat mode.
427 */
428 i = SIGBUS;
429 ucode = BUS_PAGE_FAULT;
430 } else {
431 /*
432 * Always SIGSEGV mode.
433 */
434 i = SIGSEGV;
435 ucode = SEGV_ACCERR;
436 }
437 }
438 addr = eva;
439 break;
440
441 case T_DIVIDE: /* integer divide fault */
442 ucode = FPE_INTDIV;
443 i = SIGFPE;
444 break;
445
446 #ifdef DEV_ISA
447 case T_NMI:
448 #ifdef POWERFAIL_NMI
449 #ifndef TIMER_FREQ
450 # define TIMER_FREQ 1193182
451 #endif
452 if (time_second - lastalert > 10) {
453 log(LOG_WARNING, "NMI: power fail\n");
454 sysbeep(880, hz);
455 lastalert = time_second;
456 }
457 goto userout;
458 #else /* !POWERFAIL_NMI */
459 /* machine/parity/power fail/"kitchen sink" faults */
460 if (isa_nmi(code) == 0) {
461 #ifdef KDB
462 /*
463 * NMI can be hooked up to a pushbutton
464 * for debugging.
465 */
466 if (kdb_on_nmi) {
467 printf ("NMI ... going to debugger\n");
468 kdb_trap(type, 0, frame);
469 }
470 #endif /* KDB */
471 goto userout;
472 } else if (panic_on_nmi)
473 panic("NMI indicates hardware failure");
474 goto out;
475 #endif /* POWERFAIL_NMI */
476 #endif /* DEV_ISA */
477
478 case T_OFLOW: /* integer overflow fault */
479 ucode = FPE_INTOVF;
480 i = SIGFPE;
481 break;
482
483 case T_BOUND: /* bounds check fault */
484 ucode = FPE_FLTSUB;
485 i = SIGFPE;
486 break;
487
488 case T_DNA:
489 #ifdef DEV_NPX
490 KASSERT(PCB_USER_FPU(td->td_pcb),
491 ("kernel FPU ctx has leaked"));
492 /* transparent fault (due to context switch "late") */
493 if (npxdna())
494 goto userout;
495 #endif
496 uprintf("pid %d killed due to lack of floating point\n",
497 p->p_pid);
498 i = SIGKILL;
499 ucode = 0;
500 break;
501
502 case T_FPOPFLT: /* FPU operand fetch fault */
503 ucode = ILL_COPROC;
504 i = SIGILL;
505 break;
506
507 case T_XMMFLT: /* SIMD floating-point exception */
508 #if defined(DEV_NPX) && !defined(CPU_DISABLE_SSE) && defined(I686_CPU)
509 ucode = npxtrap_sse();
510 if (ucode == -1)
511 goto userout;
512 #else
513 ucode = 0;
514 #endif
515 i = SIGFPE;
516 break;
517 #ifdef KDTRACE_HOOKS
518 case T_DTRACE_RET:
519 enable_intr();
520 fill_frame_regs(frame, ®s);
521 if (dtrace_return_probe_ptr != NULL &&
522 dtrace_return_probe_ptr(®s) == 0)
523 goto out;
524 goto userout;
525 #endif
526 }
527 } else {
528 /* kernel trap */
529
530 KASSERT(cold || td->td_ucred != NULL,
531 ("kernel trap doesn't have ucred"));
532 switch (type) {
533 case T_PAGEFLT: /* page fault */
534 (void) trap_pfault(frame, FALSE, eva);
535 goto out;
536
537 case T_DNA:
538 #ifdef DEV_NPX
539 if (PCB_USER_FPU(td->td_pcb))
540 panic("Unregistered use of FPU in kernel");
541 if (npxdna())
542 goto out;
543 #endif
544 break;
545
546 case T_ARITHTRAP: /* arithmetic trap */
547 case T_XMMFLT: /* SIMD floating-point exception */
548 case T_FPOPFLT: /* FPU operand fetch fault */
549 /*
550 * XXXKIB for now disable any FPU traps in kernel
551 * handler registration seems to be overkill
552 */
553 trap_fatal(frame, 0);
554 goto out;
555
556 /*
557 * The following two traps can happen in
558 * vm86 mode, and, if so, we want to handle
559 * them specially.
560 */
561 case T_PROTFLT: /* general protection fault */
562 case T_STKFLT: /* stack fault */
563 if (frame->tf_eflags & PSL_VM) {
564 i = vm86_emulate((struct vm86frame *)frame);
565 if (i != 0)
566 /*
567 * returns to original process
568 */
569 vm86_trap((struct vm86frame *)frame);
570 goto out;
571 }
572 /* FALL THROUGH */
573 case T_SEGNPFLT: /* segment not present fault */
574 if (curpcb->pcb_flags & PCB_VM86CALL)
575 break;
576
577 /*
578 * Invalid %fs's and %gs's can be created using
579 * procfs or PT_SETREGS or by invalidating the
580 * underlying LDT entry. This causes a fault
581 * in kernel mode when the kernel attempts to
582 * switch contexts. Lose the bad context
583 * (XXX) so that we can continue, and generate
584 * a signal.
585 */
586 if (frame->tf_eip == (int)cpu_switch_load_gs) {
587 curpcb->pcb_gs = 0;
588 #if 0
589 PROC_LOCK(p);
590 kern_psignal(p, SIGBUS);
591 PROC_UNLOCK(p);
592 #endif
593 goto out;
594 }
595
596 if (td->td_intr_nesting_level != 0)
597 break;
598
599 /*
600 * Invalid segment selectors and out of bounds
601 * %eip's and %esp's can be set up in user mode.
602 * This causes a fault in kernel mode when the
603 * kernel tries to return to user mode. We want
604 * to get this fault so that we can fix the
605 * problem here and not have to check all the
606 * selectors and pointers when the user changes
607 * them.
608 */
609 if (frame->tf_eip == (int)doreti_iret) {
610 frame->tf_eip = (int)doreti_iret_fault;
611 goto out;
612 }
613 if (type == T_STKFLT)
614 break;
615
616 if (frame->tf_eip == (int)doreti_popl_ds) {
617 frame->tf_eip = (int)doreti_popl_ds_fault;
618 goto out;
619 }
620 if (frame->tf_eip == (int)doreti_popl_es) {
621 frame->tf_eip = (int)doreti_popl_es_fault;
622 goto out;
623 }
624 if (frame->tf_eip == (int)doreti_popl_fs) {
625 frame->tf_eip = (int)doreti_popl_fs_fault;
626 goto out;
627 }
628 if (curpcb->pcb_onfault != NULL) {
629 frame->tf_eip =
630 (int)curpcb->pcb_onfault;
631 goto out;
632 }
633 break;
634
635 case T_TSSFLT:
636 /*
637 * PSL_NT can be set in user mode and isn't cleared
638 * automatically when the kernel is entered. This
639 * causes a TSS fault when the kernel attempts to
640 * `iret' because the TSS link is uninitialized. We
641 * want to get this fault so that we can fix the
642 * problem here and not every time the kernel is
643 * entered.
644 */
645 if (frame->tf_eflags & PSL_NT) {
646 frame->tf_eflags &= ~PSL_NT;
647 goto out;
648 }
649 break;
650
651 case T_TRCTRAP: /* trace trap */
652 if (frame->tf_eip == (int)IDTVEC(lcall_syscall)) {
653 /*
654 * We've just entered system mode via the
655 * syscall lcall. Continue single stepping
656 * silently until the syscall handler has
657 * saved the flags.
658 */
659 goto out;
660 }
661 if (frame->tf_eip == (int)IDTVEC(lcall_syscall) + 1) {
662 /*
663 * The syscall handler has now saved the
664 * flags. Stop single stepping it.
665 */
666 frame->tf_eflags &= ~PSL_T;
667 goto out;
668 }
669 /*
670 * Ignore debug register trace traps due to
671 * accesses in the user's address space, which
672 * can happen under several conditions such as
673 * if a user sets a watchpoint on a buffer and
674 * then passes that buffer to a system call.
675 * We still want to get TRCTRAPS for addresses
676 * in kernel space because that is useful when
677 * debugging the kernel.
678 */
679 if (user_dbreg_trap() &&
680 !(curpcb->pcb_flags & PCB_VM86CALL)) {
681 /*
682 * Reset breakpoint bits because the
683 * processor doesn't
684 */
685 load_dr6(rdr6() & 0xfffffff0);
686 goto out;
687 }
688
689 /*
690 * Malicious user code can configure a debug
691 * register watchpoint to trap on data access
692 * to the top of stack and then execute 'pop
693 * %ss; int 3'. Due to exception deferral for
694 * 'pop %ss', the CPU will not interrupt 'int
695 * 3' to raise the DB# exception for the debug
696 * register but will postpone the DB# until
697 * execution of the first instruction of the
698 * BP# handler (in kernel mode). Normally the
699 * previous check would ignore DB# exceptions
700 * for watchpoints on user addresses raised in
701 * kernel mode. However, some CPU errata
702 * include cases where DB# exceptions do not
703 * properly set bits in %dr6, e.g. Haswell
704 * HSD23 and Skylake-X SKZ24.
705 *
706 * A deferred DB# can also be raised on the
707 * first instructions of system call entry
708 * points or single-step traps via similar use
709 * of 'pop %ss' or 'mov xxx, %ss'.
710 */
711 if (frame->tf_eip ==
712 (uintptr_t)IDTVEC(int0x80_syscall) ||
713 frame->tf_eip == (uintptr_t)IDTVEC(bpt) ||
714 frame->tf_eip == (uintptr_t)IDTVEC(dbg))
715 return;
716 /*
717 * FALLTHROUGH (TRCTRAP kernel mode, kernel address)
718 */
719 case T_BPTFLT:
720 /*
721 * If KDB is enabled, let it handle the debugger trap.
722 * Otherwise, debugger traps "can't happen".
723 */
724 #ifdef KDB
725 if (kdb_trap(type, 0, frame))
726 goto out;
727 #endif
728 break;
729
730 #ifdef DEV_ISA
731 case T_NMI:
732 #ifdef POWERFAIL_NMI
733 if (time_second - lastalert > 10) {
734 log(LOG_WARNING, "NMI: power fail\n");
735 sysbeep(880, hz);
736 lastalert = time_second;
737 }
738 goto out;
739 #else /* !POWERFAIL_NMI */
740 /* machine/parity/power fail/"kitchen sink" faults */
741 if (isa_nmi(code) == 0) {
742 #ifdef KDB
743 /*
744 * NMI can be hooked up to a pushbutton
745 * for debugging.
746 */
747 if (kdb_on_nmi) {
748 printf ("NMI ... going to debugger\n");
749 kdb_trap(type, 0, frame);
750 }
751 #endif /* KDB */
752 goto out;
753 } else if (panic_on_nmi == 0)
754 goto out;
755 /* FALLTHROUGH */
756 #endif /* POWERFAIL_NMI */
757 #endif /* DEV_ISA */
758 }
759
760 trap_fatal(frame, eva);
761 goto out;
762 }
763
764 /* Translate fault for emulators (e.g. Linux) */
765 if (*p->p_sysent->sv_transtrap)
766 i = (*p->p_sysent->sv_transtrap)(i, type);
767
768 ksiginfo_init_trap(&ksi);
769 ksi.ksi_signo = i;
770 ksi.ksi_code = ucode;
771 ksi.ksi_addr = (void *)addr;
772 ksi.ksi_trapno = type;
773 if (uprintf_signal) {
774 uprintf("pid %d comm %s: signal %d err %x code %d type %d "
775 "addr 0x%x esp 0x%08x eip 0x%08x "
776 "<%02x %02x %02x %02x %02x %02x %02x %02x>\n",
777 p->p_pid, p->p_comm, i, frame->tf_err, ucode, type, addr,
778 frame->tf_esp, frame->tf_eip,
779 fubyte((void *)(frame->tf_eip + 0)),
780 fubyte((void *)(frame->tf_eip + 1)),
781 fubyte((void *)(frame->tf_eip + 2)),
782 fubyte((void *)(frame->tf_eip + 3)),
783 fubyte((void *)(frame->tf_eip + 4)),
784 fubyte((void *)(frame->tf_eip + 5)),
785 fubyte((void *)(frame->tf_eip + 6)),
786 fubyte((void *)(frame->tf_eip + 7)));
787 }
788 KASSERT((read_eflags() & PSL_I) != 0, ("interrupts disabled"));
789 trapsignal(td, &ksi);
790
791 #ifdef DEBUG
792 if (type <= MAX_TRAP_MSG) {
793 uprintf("fatal process exception: %s",
794 trap_msg[type]);
795 if ((type == T_PAGEFLT) || (type == T_PROTFLT))
796 uprintf(", fault VA = 0x%lx", (u_long)eva);
797 uprintf("\n");
798 }
799 #endif
800
801 user:
802 userret(td, frame);
803 KASSERT(PCB_USER_FPU(td->td_pcb),
804 ("Return from trap with kernel FPU ctx leaked"));
805 userout:
806 out:
807 return;
808 }
809
810 static int
trap_pfault(frame,usermode,eva)811 trap_pfault(frame, usermode, eva)
812 struct trapframe *frame;
813 int usermode;
814 vm_offset_t eva;
815 {
816 vm_offset_t va;
817 struct vmspace *vm;
818 vm_map_t map;
819 int rv = 0;
820 vm_prot_t ftype;
821 struct thread *td = curthread;
822 struct proc *p = td->td_proc;
823
824 if (__predict_false((td->td_pflags & TDP_NOFAULTING) != 0)) {
825 /*
826 * Due to both processor errata and lazy TLB invalidation when
827 * access restrictions are removed from virtual pages, memory
828 * accesses that are allowed by the physical mapping layer may
829 * nonetheless cause one spurious page fault per virtual page.
830 * When the thread is executing a "no faulting" section that
831 * is bracketed by vm_fault_{disable,enable}_pagefaults(),
832 * every page fault is treated as a spurious page fault,
833 * unless it accesses the same virtual address as the most
834 * recent page fault within the same "no faulting" section.
835 */
836 if (td->td_md.md_spurflt_addr != eva ||
837 (td->td_pflags & TDP_RESETSPUR) != 0) {
838 /*
839 * Do nothing to the TLB. A stale TLB entry is
840 * flushed automatically by a page fault.
841 */
842 td->td_md.md_spurflt_addr = eva;
843 td->td_pflags &= ~TDP_RESETSPUR;
844 return (0);
845 }
846 } else {
847 /*
848 * If we get a page fault while in a critical section, then
849 * it is most likely a fatal kernel page fault. The kernel
850 * is already going to panic trying to get a sleep lock to
851 * do the VM lookup, so just consider it a fatal trap so the
852 * kernel can print out a useful trap message and even get
853 * to the debugger.
854 *
855 * If we get a page fault while holding a non-sleepable
856 * lock, then it is most likely a fatal kernel page fault.
857 * If WITNESS is enabled, then it's going to whine about
858 * bogus LORs with various VM locks, so just skip to the
859 * fatal trap handling directly.
860 */
861 if (td->td_critnest != 0 ||
862 WITNESS_CHECK(WARN_SLEEPOK | WARN_GIANTOK, NULL,
863 "Kernel page fault") != 0) {
864 trap_fatal(frame, eva);
865 return (-1);
866 }
867 }
868 va = trunc_page(eva);
869 if (va >= KERNBASE) {
870 /*
871 * Don't allow user-mode faults in kernel address space.
872 * An exception: if the faulting address is the invalid
873 * instruction entry in the IDT, then the Intel Pentium
874 * F00F bug workaround was triggered, and we need to
875 * treat it is as an illegal instruction, and not a page
876 * fault.
877 */
878 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
879 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug)
880 return (-2);
881 #endif
882 if (usermode)
883 goto nogo;
884
885 map = kernel_map;
886 } else {
887 /*
888 * This is a fault on non-kernel virtual memory. If either
889 * p or p->p_vmspace is NULL, then the fault is fatal.
890 */
891 if (p == NULL || (vm = p->p_vmspace) == NULL)
892 goto nogo;
893
894 map = &vm->vm_map;
895
896 /*
897 * When accessing a user-space address, kernel must be
898 * ready to accept the page fault, and provide a
899 * handling routine. Since accessing the address
900 * without the handler is a bug, do not try to handle
901 * it normally, and panic immediately.
902 */
903 if (!usermode && (td->td_intr_nesting_level != 0 ||
904 curpcb->pcb_onfault == NULL)) {
905 trap_fatal(frame, eva);
906 return (-1);
907 }
908 }
909
910 /*
911 * If the trap was caused by errant bits in the PTE then panic.
912 */
913 if (frame->tf_err & PGEX_RSV) {
914 trap_fatal(frame, eva);
915 return (-1);
916 }
917
918 /*
919 * PGEX_I is defined only if the execute disable bit capability is
920 * supported and enabled.
921 */
922 if (frame->tf_err & PGEX_W)
923 ftype = VM_PROT_WRITE;
924 #if defined(PAE) || defined(PAE_TABLES)
925 else if ((frame->tf_err & PGEX_I) && pg_nx != 0)
926 ftype = VM_PROT_EXECUTE;
927 #endif
928 else
929 ftype = VM_PROT_READ;
930
931 if (map != kernel_map) {
932 /*
933 * Keep swapout from messing with us during this
934 * critical time.
935 */
936 PROC_LOCK(p);
937 ++p->p_lock;
938 PROC_UNLOCK(p);
939
940 /* Fault in the user page: */
941 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
942
943 PROC_LOCK(p);
944 --p->p_lock;
945 PROC_UNLOCK(p);
946 } else {
947 /*
948 * Don't have to worry about process locking or stacks in the
949 * kernel.
950 */
951 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
952 }
953 if (rv == KERN_SUCCESS) {
954 #ifdef HWPMC_HOOKS
955 if (ftype == VM_PROT_READ || ftype == VM_PROT_WRITE) {
956 PMC_SOFT_CALL_TF( , , page_fault, all, frame);
957 if (ftype == VM_PROT_READ)
958 PMC_SOFT_CALL_TF( , , page_fault, read,
959 frame);
960 else
961 PMC_SOFT_CALL_TF( , , page_fault, write,
962 frame);
963 }
964 #endif
965 return (0);
966 }
967 nogo:
968 if (!usermode) {
969 if (td->td_intr_nesting_level == 0 &&
970 curpcb->pcb_onfault != NULL) {
971 frame->tf_eip = (int)curpcb->pcb_onfault;
972 return (0);
973 }
974 trap_fatal(frame, eva);
975 return (-1);
976 }
977 return ((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
978 }
979
980 static void
trap_fatal(frame,eva)981 trap_fatal(frame, eva)
982 struct trapframe *frame;
983 vm_offset_t eva;
984 {
985 int code, ss, esp;
986 u_int type;
987 struct soft_segment_descriptor softseg;
988 char *msg;
989 #ifdef KDB
990 bool handled;
991 #endif
992
993 code = frame->tf_err;
994 type = frame->tf_trapno;
995 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg);
996
997 if (type <= MAX_TRAP_MSG)
998 msg = trap_msg[type];
999 else
1000 msg = "UNKNOWN";
1001 printf("\n\nFatal trap %d: %s while in %s mode\n", type, msg,
1002 frame->tf_eflags & PSL_VM ? "vm86" :
1003 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel");
1004 #ifdef SMP
1005 /* two separate prints in case of a trap on an unmapped page */
1006 printf("cpuid = %d; ", PCPU_GET(cpuid));
1007 printf("apic id = %02x\n", PCPU_GET(apic_id));
1008 #endif
1009 if (type == T_PAGEFLT) {
1010 printf("fault virtual address = 0x%x\n", eva);
1011 printf("fault code = %s %s%s, %s\n",
1012 code & PGEX_U ? "user" : "supervisor",
1013 code & PGEX_W ? "write" : "read",
1014 #if defined(PAE) || defined(PAE_TABLES)
1015 pg_nx != 0 ?
1016 (code & PGEX_I ? " instruction" : " data") :
1017 #endif
1018 "",
1019 code & PGEX_RSV ? "reserved bits in PTE" :
1020 code & PGEX_P ? "protection violation" : "page not present");
1021 }
1022 printf("instruction pointer = 0x%x:0x%x\n",
1023 frame->tf_cs & 0xffff, frame->tf_eip);
1024 if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) {
1025 ss = frame->tf_ss & 0xffff;
1026 esp = frame->tf_esp;
1027 } else {
1028 ss = GSEL(GDATA_SEL, SEL_KPL);
1029 esp = (int)&frame->tf_esp;
1030 }
1031 printf("stack pointer = 0x%x:0x%x\n", ss, esp);
1032 printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp);
1033 printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n",
1034 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type);
1035 printf(" = DPL %d, pres %d, def32 %d, gran %d\n",
1036 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32,
1037 softseg.ssd_gran);
1038 printf("processor eflags = ");
1039 if (frame->tf_eflags & PSL_T)
1040 printf("trace trap, ");
1041 if (frame->tf_eflags & PSL_I)
1042 printf("interrupt enabled, ");
1043 if (frame->tf_eflags & PSL_NT)
1044 printf("nested task, ");
1045 if (frame->tf_eflags & PSL_RF)
1046 printf("resume, ");
1047 if (frame->tf_eflags & PSL_VM)
1048 printf("vm86, ");
1049 printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12);
1050 printf("current process = %d (%s)\n",
1051 curproc->p_pid, curthread->td_name);
1052
1053 #ifdef KDB
1054 if (debugger_on_panic) {
1055 kdb_why = KDB_WHY_TRAP;
1056 frame->tf_err = eva; /* smuggle fault address to ddb */
1057 handled = kdb_trap(type, 0, frame);
1058 frame->tf_err = code; /* restore error code */
1059 kdb_why = KDB_WHY_UNSET;
1060 if (handled)
1061 return;
1062 }
1063 #endif
1064 printf("trap number = %d\n", type);
1065 if (type <= MAX_TRAP_MSG)
1066 panic("%s", trap_msg[type]);
1067 else
1068 panic("unknown/reserved trap");
1069 }
1070
1071 /*
1072 * Double fault handler. Called when a fault occurs while writing
1073 * a frame for a trap/exception onto the stack. This usually occurs
1074 * when the stack overflows (such is the case with infinite recursion,
1075 * for example).
1076 *
1077 * XXX Note that the current PTD gets replaced by IdlePTD when the
1078 * task switch occurs. This means that the stack that was active at
1079 * the time of the double fault is not available at <kstack> unless
1080 * the machine was idle when the double fault occurred. The downside
1081 * of this is that "trace <ebp>" in ddb won't work.
1082 */
1083 void
dblfault_handler()1084 dblfault_handler()
1085 {
1086 #ifdef KDTRACE_HOOKS
1087 if (dtrace_doubletrap_func != NULL)
1088 (*dtrace_doubletrap_func)();
1089 #endif
1090 printf("\nFatal double fault:\n");
1091 printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip));
1092 printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp));
1093 printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp));
1094 #ifdef SMP
1095 /* two separate prints in case of a trap on an unmapped page */
1096 printf("cpuid = %d; ", PCPU_GET(cpuid));
1097 printf("apic id = %02x\n", PCPU_GET(apic_id));
1098 #endif
1099 panic("double fault");
1100 }
1101
1102 int
cpu_fetch_syscall_args(struct thread * td,struct syscall_args * sa)1103 cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
1104 {
1105 struct proc *p;
1106 struct trapframe *frame;
1107 caddr_t params;
1108 long tmp;
1109 int error;
1110
1111 p = td->td_proc;
1112 frame = td->td_frame;
1113
1114 params = (caddr_t)frame->tf_esp + sizeof(int);
1115 sa->code = frame->tf_eax;
1116
1117 /*
1118 * Need to check if this is a 32 bit or 64 bit syscall.
1119 */
1120 if (sa->code == SYS_syscall) {
1121 /*
1122 * Code is first argument, followed by actual args.
1123 */
1124 error = fueword(params, &tmp);
1125 if (error == -1)
1126 return (EFAULT);
1127 sa->code = tmp;
1128 params += sizeof(int);
1129 } else if (sa->code == SYS___syscall) {
1130 /*
1131 * Like syscall, but code is a quad, so as to maintain
1132 * quad alignment for the rest of the arguments.
1133 */
1134 error = fueword(params, &tmp);
1135 if (error == -1)
1136 return (EFAULT);
1137 sa->code = tmp;
1138 params += sizeof(quad_t);
1139 }
1140
1141 if (p->p_sysent->sv_mask)
1142 sa->code &= p->p_sysent->sv_mask;
1143 if (sa->code >= p->p_sysent->sv_size)
1144 sa->callp = &p->p_sysent->sv_table[0];
1145 else
1146 sa->callp = &p->p_sysent->sv_table[sa->code];
1147 sa->narg = sa->callp->sy_narg;
1148
1149 if (params != NULL && sa->narg != 0)
1150 error = copyin(params, (caddr_t)sa->args,
1151 (u_int)(sa->narg * sizeof(int)));
1152 else
1153 error = 0;
1154
1155 if (error == 0) {
1156 td->td_retval[0] = 0;
1157 td->td_retval[1] = frame->tf_edx;
1158 }
1159
1160 return (error);
1161 }
1162
1163 #include "../../kern/subr_syscall.c"
1164
1165 /*
1166 * syscall - system call request C handler. A system call is
1167 * essentially treated as a trap by reusing the frame layout.
1168 */
1169 void
syscall(struct trapframe * frame)1170 syscall(struct trapframe *frame)
1171 {
1172 struct thread *td;
1173 struct syscall_args sa;
1174 register_t orig_tf_eflags;
1175 int error;
1176 ksiginfo_t ksi;
1177
1178 #ifdef DIAGNOSTIC
1179 if (ISPL(frame->tf_cs) != SEL_UPL) {
1180 panic("syscall");
1181 /* NOT REACHED */
1182 }
1183 #endif
1184 orig_tf_eflags = frame->tf_eflags;
1185
1186 td = curthread;
1187 td->td_frame = frame;
1188
1189 error = syscallenter(td, &sa);
1190
1191 /*
1192 * Traced syscall.
1193 */
1194 if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) {
1195 frame->tf_eflags &= ~PSL_T;
1196 ksiginfo_init_trap(&ksi);
1197 ksi.ksi_signo = SIGTRAP;
1198 ksi.ksi_code = TRAP_TRACE;
1199 ksi.ksi_addr = (void *)frame->tf_eip;
1200 trapsignal(td, &ksi);
1201 }
1202
1203 KASSERT(PCB_USER_FPU(td->td_pcb),
1204 ("System call %s returning with kernel FPU ctx leaked",
1205 syscallname(td->td_proc, sa.code)));
1206 KASSERT(td->td_pcb->pcb_save == get_pcb_user_save_td(td),
1207 ("System call %s returning with mangled pcb_save",
1208 syscallname(td->td_proc, sa.code)));
1209
1210 syscallret(td, error, &sa);
1211 }
1212