1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2004 The FreeBSD Project
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 #include "opt_kdb.h"
31 #include "opt_stack.h"
32
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/cons.h>
36 #include <sys/kdb.h>
37 #include <sys/kernel.h>
38 #include <sys/malloc.h>
39 #include <sys/lock.h>
40 #include <sys/pcpu.h>
41 #include <sys/priv.h>
42 #include <sys/proc.h>
43 #include <sys/sbuf.h>
44 #include <sys/smp.h>
45 #include <sys/stack.h>
46 #include <sys/sysctl.h>
47 #include <sys/tslog.h>
48
49 #include <machine/kdb.h>
50 #include <machine/pcb.h>
51
52 #ifdef SMP
53 #include <machine/smp.h>
54 #endif
55
56 #include <security/mac/mac_framework.h>
57
58 u_char __read_frequently kdb_active = 0;
59 static void *kdb_jmpbufp = NULL;
60 struct kdb_dbbe *kdb_dbbe = NULL;
61 static struct pcb kdb_pcb;
62 struct pcb *kdb_thrctx = NULL;
63 struct thread *kdb_thread = NULL;
64 struct trapframe *kdb_frame = NULL;
65
66 #ifdef BREAK_TO_DEBUGGER
67 #define KDB_BREAK_TO_DEBUGGER 1
68 #else
69 #define KDB_BREAK_TO_DEBUGGER 0
70 #endif
71
72 #ifdef ALT_BREAK_TO_DEBUGGER
73 #define KDB_ALT_BREAK_TO_DEBUGGER 1
74 #else
75 #define KDB_ALT_BREAK_TO_DEBUGGER 0
76 #endif
77
78 static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
79 static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
80 static int kdb_enter_securelevel = 0;
81
82 KDB_BACKEND(null, NULL, NULL, NULL, NULL);
83
84 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
85 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
86 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
87 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
88 static int kdb_sysctl_panic_str(SYSCTL_HANDLER_ARGS);
89 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
90 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
91 static int kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS);
92
93 static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
94 "KDB nodes");
95
96 SYSCTL_PROC(_debug_kdb, OID_AUTO, available,
97 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
98 kdb_sysctl_available, "A",
99 "list of available KDB backends");
100
101 SYSCTL_PROC(_debug_kdb, OID_AUTO, current,
102 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
103 kdb_sysctl_current, "A",
104 "currently selected KDB backend");
105
106 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter,
107 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
108 kdb_sysctl_enter, "I",
109 "set to enter the debugger");
110
111 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic,
112 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0,
113 kdb_sysctl_panic, "I",
114 "set to panic the kernel");
115
116 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic_str,
117 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0,
118 kdb_sysctl_panic_str, "A",
119 "trigger a kernel panic, using the provided string as the panic message");
120
121 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap,
122 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0,
123 kdb_sysctl_trap, "I",
124 "set to cause a page fault via data access");
125
126 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code,
127 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0,
128 kdb_sysctl_trap_code, "I",
129 "set to cause a page fault via code access");
130
131 SYSCTL_PROC(_debug_kdb, OID_AUTO, stack_overflow,
132 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0,
133 kdb_sysctl_stack_overflow, "I",
134 "set to cause a stack overflow");
135
136 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger,
137 CTLFLAG_RWTUN,
138 &kdb_break_to_debugger, 0, "Enable break to debugger");
139
140 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger,
141 CTLFLAG_RWTUN,
142 &kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger");
143
144 SYSCTL_INT(_debug_kdb, OID_AUTO, enter_securelevel,
145 CTLFLAG_RWTUN | CTLFLAG_SECURE,
146 &kdb_enter_securelevel, 0,
147 "Maximum securelevel to enter a KDB backend");
148
149 /*
150 * Flag to indicate to debuggers why the debugger was entered.
151 */
152 const char * volatile kdb_why = KDB_WHY_UNSET;
153
154 static int
kdb_sysctl_available(SYSCTL_HANDLER_ARGS)155 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
156 {
157 struct kdb_dbbe **iter;
158 struct sbuf sbuf;
159 int error;
160
161 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
162 SET_FOREACH(iter, kdb_dbbe_set) {
163 if ((*iter)->dbbe_active == 0)
164 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
165 }
166 error = sbuf_finish(&sbuf);
167 sbuf_delete(&sbuf);
168 return (error);
169 }
170
171 static int
kdb_sysctl_current(SYSCTL_HANDLER_ARGS)172 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
173 {
174 char buf[16];
175 int error;
176
177 if (kdb_dbbe != NULL)
178 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
179 else
180 *buf = '\0';
181 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
182 if (error != 0 || req->newptr == NULL)
183 return (error);
184 if (kdb_active)
185 return (EBUSY);
186 return (kdb_dbbe_select(buf));
187 }
188
189 static int
kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)190 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
191 {
192 int error, i;
193
194 error = sysctl_wire_old_buffer(req, sizeof(int));
195 if (error == 0) {
196 i = 0;
197 error = sysctl_handle_int(oidp, &i, 0, req);
198 }
199 if (error != 0 || req->newptr == NULL)
200 return (error);
201 if (kdb_active)
202 return (EBUSY);
203 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
204 return (0);
205 }
206
207 static int
kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)208 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
209 {
210 int error, i;
211
212 error = sysctl_wire_old_buffer(req, sizeof(int));
213 if (error == 0) {
214 i = 0;
215 error = sysctl_handle_int(oidp, &i, 0, req);
216 }
217 if (error != 0 || req->newptr == NULL)
218 return (error);
219 panic("kdb_sysctl_panic");
220 return (0);
221 }
222
223 static int
kdb_sysctl_panic_str(SYSCTL_HANDLER_ARGS)224 kdb_sysctl_panic_str(SYSCTL_HANDLER_ARGS)
225 {
226 int error;
227 static char buf[256]; /* static buffer to limit mallocs when panicing */
228
229 *buf = '\0';
230 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
231 if (error != 0 || req->newptr == NULL)
232 return (error);
233 panic("kdb_sysctl_panic: %s", buf);
234 return (0);
235 }
236
237 static int
kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)238 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
239 {
240 int error, i;
241 int *addr = (int *)0x10;
242
243 error = sysctl_wire_old_buffer(req, sizeof(int));
244 if (error == 0) {
245 i = 0;
246 error = sysctl_handle_int(oidp, &i, 0, req);
247 }
248 if (error != 0 || req->newptr == NULL)
249 return (error);
250 return (*addr);
251 }
252
253 static int
kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)254 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
255 {
256 int error, i;
257 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
258
259 error = sysctl_wire_old_buffer(req, sizeof(int));
260 if (error == 0) {
261 i = 0;
262 error = sysctl_handle_int(oidp, &i, 0, req);
263 }
264 if (error != 0 || req->newptr == NULL)
265 return (error);
266 (*fp)(0x11111111, 0x22222222, 0x33333333);
267 return (0);
268 }
269
270 static void kdb_stack_overflow(volatile int *x) __noinline;
271 static void
kdb_stack_overflow(volatile int * x)272 kdb_stack_overflow(volatile int *x)
273 {
274
275 if (*x > 10000000)
276 return;
277 kdb_stack_overflow(x);
278 *x += PCPU_GET(cpuid) / 1000000;
279 }
280
281 static int
kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS)282 kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS)
283 {
284 int error, i;
285 volatile int x;
286
287 error = sysctl_wire_old_buffer(req, sizeof(int));
288 if (error == 0) {
289 i = 0;
290 error = sysctl_handle_int(oidp, &i, 0, req);
291 }
292 if (error != 0 || req->newptr == NULL)
293 return (error);
294 x = 0;
295 kdb_stack_overflow(&x);
296 return (0);
297 }
298
299 void
kdb_panic(const char * msg)300 kdb_panic(const char *msg)
301 {
302
303 kdb_why = KDB_WHY_PANIC;
304 printf("KDB: panic\n");
305 panic("%s", msg);
306 }
307
308 void
kdb_reboot(void)309 kdb_reboot(void)
310 {
311
312 kdb_why = KDB_WHY_REBOOT;
313 printf("KDB: reboot requested\n");
314 shutdown_nice(0);
315 }
316
317 /*
318 * Solaris implements a new BREAK which is initiated by a character sequence
319 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
320 * Remote Console.
321 *
322 * Note that this function may be called from almost anywhere, with interrupts
323 * disabled and with unknown locks held, so it must not access data other than
324 * its arguments. Its up to the caller to ensure that the state variable is
325 * consistent.
326 */
327 #define KEY_CR 13 /* CR '\r' */
328 #define KEY_TILDE 126 /* ~ */
329 #define KEY_CRTLB 2 /* ^B */
330 #define KEY_CRTLP 16 /* ^P */
331 #define KEY_CRTLR 18 /* ^R */
332
333 /* States of th KDB "alternate break sequence" detecting state machine. */
334 enum {
335 KDB_ALT_BREAK_SEEN_NONE,
336 KDB_ALT_BREAK_SEEN_CR,
337 KDB_ALT_BREAK_SEEN_CR_TILDE,
338 };
339
340 int
kdb_break(void)341 kdb_break(void)
342 {
343
344 if (!kdb_break_to_debugger)
345 return (0);
346 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
347 return (KDB_REQ_DEBUGGER);
348 }
349
350 static int
kdb_alt_break_state(int key,int * state)351 kdb_alt_break_state(int key, int *state)
352 {
353 int brk;
354
355 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
356 if (key == KEY_CR) {
357 *state = KDB_ALT_BREAK_SEEN_CR;
358 return (0);
359 }
360
361 brk = 0;
362 switch (*state) {
363 case KDB_ALT_BREAK_SEEN_CR:
364 *state = KDB_ALT_BREAK_SEEN_NONE;
365 if (key == KEY_TILDE)
366 *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
367 break;
368 case KDB_ALT_BREAK_SEEN_CR_TILDE:
369 *state = KDB_ALT_BREAK_SEEN_NONE;
370 if (key == KEY_CRTLB)
371 brk = KDB_REQ_DEBUGGER;
372 else if (key == KEY_CRTLP)
373 brk = KDB_REQ_PANIC;
374 else if (key == KEY_CRTLR)
375 brk = KDB_REQ_REBOOT;
376 break;
377 case KDB_ALT_BREAK_SEEN_NONE:
378 default:
379 *state = KDB_ALT_BREAK_SEEN_NONE;
380 break;
381 }
382 return (brk);
383 }
384
385 static int
kdb_alt_break_internal(int key,int * state,int force_gdb)386 kdb_alt_break_internal(int key, int *state, int force_gdb)
387 {
388 int brk;
389
390 if (!kdb_alt_break_to_debugger)
391 return (0);
392 brk = kdb_alt_break_state(key, state);
393 switch (brk) {
394 case KDB_REQ_DEBUGGER:
395 if (force_gdb)
396 kdb_dbbe_select("gdb");
397 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
398 break;
399
400 case KDB_REQ_PANIC:
401 if (force_gdb)
402 kdb_dbbe_select("gdb");
403 kdb_panic("Panic sequence on console");
404 break;
405
406 case KDB_REQ_REBOOT:
407 kdb_reboot();
408 break;
409 }
410 return (0);
411 }
412
413 int
kdb_alt_break(int key,int * state)414 kdb_alt_break(int key, int *state)
415 {
416
417 return (kdb_alt_break_internal(key, state, 0));
418 }
419
420 /*
421 * This variation on kdb_alt_break() is used only by dcons, which has its own
422 * configuration flag to force GDB use regardless of the global KDB
423 * configuration.
424 */
425 int
kdb_alt_break_gdb(int key,int * state)426 kdb_alt_break_gdb(int key, int *state)
427 {
428
429 return (kdb_alt_break_internal(key, state, 1));
430 }
431
432 /*
433 * Print a backtrace of the calling thread. The backtrace is generated by
434 * the selected debugger, provided it supports backtraces. If no debugger
435 * is selected or the current debugger does not support backtraces, this
436 * function silently returns.
437 */
438 void
kdb_backtrace(void)439 kdb_backtrace(void)
440 {
441
442 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
443 printf("KDB: stack backtrace:\n");
444 kdb_dbbe->dbbe_trace();
445 }
446 #ifdef STACK
447 else {
448 struct stack st;
449
450 printf("KDB: stack backtrace:\n");
451 stack_save(&st);
452 stack_print_ddb(&st);
453 }
454 #endif
455 }
456
457 /*
458 * Similar to kdb_backtrace() except that it prints a backtrace of an
459 * arbitrary thread rather than the calling thread.
460 */
461 void
kdb_backtrace_thread(struct thread * td)462 kdb_backtrace_thread(struct thread *td)
463 {
464
465 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
466 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
467 kdb_dbbe->dbbe_trace_thread(td);
468 }
469 #ifdef STACK
470 else {
471 struct stack st;
472
473 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
474 if (stack_save_td(&st, td) == 0)
475 stack_print_ddb(&st);
476 }
477 #endif
478 }
479
480 /*
481 * Set/change the current backend.
482 */
483 int
kdb_dbbe_select(const char * name)484 kdb_dbbe_select(const char *name)
485 {
486 struct kdb_dbbe *be, **iter;
487 int error;
488
489 error = priv_check(curthread, PRIV_KDB_SET_BACKEND);
490 if (error)
491 return (error);
492
493 SET_FOREACH(iter, kdb_dbbe_set) {
494 be = *iter;
495 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
496 kdb_dbbe = be;
497 return (0);
498 }
499 }
500 return (EINVAL);
501 }
502
503 static bool
kdb_backend_permitted(struct kdb_dbbe * be,struct thread * td)504 kdb_backend_permitted(struct kdb_dbbe *be, struct thread *td)
505 {
506 struct ucred *cred;
507 int error;
508
509 cred = td->td_ucred;
510 if (cred == NULL) {
511 KASSERT(td == &thread0 && cold,
512 ("%s: missing cred for %p", __func__, td));
513 error = 0;
514 } else {
515 error = securelevel_gt(cred, kdb_enter_securelevel);
516 }
517 #ifdef MAC
518 /*
519 * Give MAC a chance to weigh in on the policy: if the securelevel is
520 * not raised, then MAC may veto the backend, otherwise MAC may
521 * explicitly grant access.
522 */
523 if (error == 0) {
524 error = mac_kdb_check_backend(be);
525 if (error != 0) {
526 printf("MAC prevented execution of KDB backend: %s\n",
527 be->dbbe_name);
528 return (false);
529 }
530 } else if (mac_kdb_grant_backend(be) == 0) {
531 error = 0;
532 }
533 #endif
534 if (error != 0)
535 printf("refusing to enter KDB with elevated securelevel\n");
536 return (error == 0);
537 }
538
539 /*
540 * Enter the currently selected debugger. If a message has been provided,
541 * it is printed first. If the debugger does not support the enter method,
542 * it is entered by using breakpoint(), which enters the debugger through
543 * kdb_trap(). The 'why' argument will contain a more mechanically usable
544 * string than 'msg', and is relied upon by DDB scripting to identify the
545 * reason for entering the debugger so that the right script can be run.
546 */
547 void
kdb_enter(const char * why,const char * msg)548 kdb_enter(const char *why, const char *msg)
549 {
550
551 if (kdb_dbbe != NULL && kdb_active == 0) {
552 kdb_why = why;
553 if (msg != NULL)
554 printf("KDB: enter: %s\n", msg);
555 breakpoint();
556 kdb_why = KDB_WHY_UNSET;
557 }
558 }
559
560 /*
561 * Initialize the kernel debugger interface.
562 */
563 void
kdb_init(void)564 kdb_init(void)
565 {
566 struct kdb_dbbe *be, **iter;
567 int cur_pri, pri;
568
569 TSENTER();
570 kdb_active = 0;
571 kdb_dbbe = NULL;
572 cur_pri = -1;
573 SET_FOREACH(iter, kdb_dbbe_set) {
574 be = *iter;
575 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
576 be->dbbe_active = (pri >= 0) ? 0 : -1;
577 if (pri > cur_pri) {
578 cur_pri = pri;
579 kdb_dbbe = be;
580 }
581 }
582 if (kdb_dbbe != NULL) {
583 printf("KDB: debugger backends:");
584 SET_FOREACH(iter, kdb_dbbe_set) {
585 be = *iter;
586 if (be->dbbe_active == 0)
587 printf(" %s", be->dbbe_name);
588 }
589 printf("\n");
590 printf("KDB: current backend: %s\n",
591 kdb_dbbe->dbbe_name);
592 }
593 TSEXIT();
594 }
595
596 /*
597 * Handle contexts.
598 */
599 void *
kdb_jmpbuf(jmp_buf new)600 kdb_jmpbuf(jmp_buf new)
601 {
602 void *old;
603
604 old = kdb_jmpbufp;
605 kdb_jmpbufp = new;
606 return (old);
607 }
608
609 void
kdb_reenter(void)610 kdb_reenter(void)
611 {
612
613 if (!kdb_active || kdb_jmpbufp == NULL)
614 return;
615
616 printf("KDB: reentering\n");
617 kdb_backtrace();
618 longjmp(kdb_jmpbufp, 1);
619 /* NOTREACHED */
620 }
621
622 void
kdb_reenter_silent(void)623 kdb_reenter_silent(void)
624 {
625
626 if (!kdb_active || kdb_jmpbufp == NULL)
627 return;
628
629 longjmp(kdb_jmpbufp, 1);
630 /* NOTREACHED */
631 }
632
633 /*
634 * Thread-related support functions.
635 */
636 struct pcb *
kdb_thr_ctx(struct thread * thr)637 kdb_thr_ctx(struct thread *thr)
638 {
639 #ifdef SMP
640 struct pcpu *pc;
641 #endif
642
643 if (thr == curthread)
644 return (&kdb_pcb);
645
646 #ifdef SMP
647 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
648 if (pc->pc_curthread == thr &&
649 CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
650 return (&stoppcbs[pc->pc_cpuid]);
651 }
652 #endif
653 return (thr->td_pcb);
654 }
655
656 struct thread *
kdb_thr_first(void)657 kdb_thr_first(void)
658 {
659 struct proc *p;
660 struct thread *thr;
661 u_int i;
662
663 /* This function may be called early. */
664 if (pidhashtbl == NULL)
665 return (&thread0);
666
667 for (i = 0; i <= pidhash; i++) {
668 LIST_FOREACH(p, &pidhashtbl[i], p_hash) {
669 thr = FIRST_THREAD_IN_PROC(p);
670 if (thr != NULL)
671 return (thr);
672 }
673 }
674 return (NULL);
675 }
676
677 struct thread *
kdb_thr_from_pid(pid_t pid)678 kdb_thr_from_pid(pid_t pid)
679 {
680 struct proc *p;
681
682 LIST_FOREACH(p, PIDHASH(pid), p_hash) {
683 if (p->p_pid == pid)
684 return (FIRST_THREAD_IN_PROC(p));
685 }
686 return (NULL);
687 }
688
689 struct thread *
kdb_thr_lookup(lwpid_t tid)690 kdb_thr_lookup(lwpid_t tid)
691 {
692 struct thread *thr;
693
694 thr = kdb_thr_first();
695 while (thr != NULL && thr->td_tid != tid)
696 thr = kdb_thr_next(thr);
697 return (thr);
698 }
699
700 struct thread *
kdb_thr_next(struct thread * thr)701 kdb_thr_next(struct thread *thr)
702 {
703 struct proc *p;
704 u_int hash;
705
706 p = thr->td_proc;
707 thr = TAILQ_NEXT(thr, td_plist);
708 if (thr != NULL)
709 return (thr);
710 if (pidhashtbl == NULL)
711 return (NULL);
712 hash = p->p_pid & pidhash;
713 for (;;) {
714 p = LIST_NEXT(p, p_hash);
715 while (p == NULL) {
716 if (++hash > pidhash)
717 return (NULL);
718 p = LIST_FIRST(&pidhashtbl[hash]);
719 }
720 thr = FIRST_THREAD_IN_PROC(p);
721 if (thr != NULL)
722 return (thr);
723 }
724 }
725
726 int
kdb_thr_select(struct thread * thr)727 kdb_thr_select(struct thread *thr)
728 {
729 if (thr == NULL)
730 return (EINVAL);
731 kdb_thread = thr;
732 kdb_thrctx = kdb_thr_ctx(thr);
733 return (0);
734 }
735
736 /*
737 * Enter the debugger due to a trap.
738 */
739 int
kdb_trap(int type,int code,struct trapframe * tf)740 kdb_trap(int type, int code, struct trapframe *tf)
741 {
742 #ifdef SMP
743 cpuset_t other_cpus;
744 #endif
745 struct kdb_dbbe *be;
746 register_t intr;
747 int handled;
748 int did_stop_cpus;
749
750 be = kdb_dbbe;
751 if (be == NULL || be->dbbe_trap == NULL)
752 return (0);
753
754 /* We reenter the debugger through kdb_reenter(). */
755 if (kdb_active)
756 return (0);
757
758 intr = intr_disable();
759
760 if (!SCHEDULER_STOPPED()) {
761 #ifdef SMP
762 other_cpus = all_cpus;
763 CPU_ANDNOT(&other_cpus, &other_cpus, &stopped_cpus);
764 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
765 stop_cpus_hard(other_cpus);
766 #endif
767 scheduler_stopped = true;
768 did_stop_cpus = 1;
769 } else
770 did_stop_cpus = 0;
771
772 kdb_active++;
773
774 kdb_frame = tf;
775
776 /* Let MD code do its thing first... */
777 kdb_cpu_trap(type, code);
778
779 makectx(tf, &kdb_pcb);
780 kdb_thr_select(curthread);
781
782 cngrab();
783
784 for (;;) {
785 if (!kdb_backend_permitted(be, curthread)) {
786 /* Unhandled breakpoint traps are fatal. */
787 handled = 1;
788 break;
789 }
790 handled = be->dbbe_trap(type, code);
791 if (be == kdb_dbbe)
792 break;
793 be = kdb_dbbe;
794 if (be == NULL || be->dbbe_trap == NULL)
795 break;
796 printf("Switching to %s back-end\n", be->dbbe_name);
797 }
798
799 cnungrab();
800
801 kdb_active--;
802
803 if (did_stop_cpus) {
804 scheduler_stopped = false;
805 #ifdef SMP
806 CPU_AND(&other_cpus, &other_cpus, &stopped_cpus);
807 restart_cpus(other_cpus);
808 #endif
809 }
810
811 intr_restore(intr);
812
813 return (handled);
814 }
815