2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2004 The FreeBSD Project
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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.
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.
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
33 #include "opt_stack.h"
35 #include <sys/param.h>
36 #include <sys/systm.h>
39 #include <sys/kernel.h>
40 #include <sys/malloc.h>
45 #include <sys/stack.h>
46 #include <sys/sysctl.h>
48 #include <machine/kdb.h>
49 #include <machine/pcb.h>
52 #include <machine/smp.h>
55 u_char __read_frequently kdb_active = 0;
56 static void *kdb_jmpbufp = NULL;
57 struct kdb_dbbe *kdb_dbbe = NULL;
58 static struct pcb kdb_pcb;
59 struct pcb *kdb_thrctx = NULL;
60 struct thread *kdb_thread = NULL;
61 struct trapframe *kdb_frame = NULL;
63 #ifdef BREAK_TO_DEBUGGER
64 #define KDB_BREAK_TO_DEBUGGER 1
66 #define KDB_BREAK_TO_DEBUGGER 0
69 #ifdef ALT_BREAK_TO_DEBUGGER
70 #define KDB_ALT_BREAK_TO_DEBUGGER 1
72 #define KDB_ALT_BREAK_TO_DEBUGGER 0
75 static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
76 static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
78 KDB_BACKEND(null, NULL, NULL, NULL, NULL);
79 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
81 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
82 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
83 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
84 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
85 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
86 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
88 static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
90 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
91 0, kdb_sysctl_available, "A", "list of available KDB backends");
93 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
94 0, kdb_sysctl_current, "A", "currently selected KDB backend");
96 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter,
97 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
98 kdb_sysctl_enter, "I", "set to enter the debugger");
100 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic,
101 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
102 kdb_sysctl_panic, "I", "set to panic the kernel");
104 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap,
105 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
106 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
108 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code,
109 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
110 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
112 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger,
113 CTLFLAG_RWTUN | CTLFLAG_SECURE,
114 &kdb_break_to_debugger, 0, "Enable break to debugger");
116 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger,
117 CTLFLAG_RWTUN | CTLFLAG_SECURE,
118 &kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger");
121 * Flag to indicate to debuggers why the debugger was entered.
123 const char * volatile kdb_why = KDB_WHY_UNSET;
126 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
128 struct kdb_dbbe **iter;
132 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
133 SET_FOREACH(iter, kdb_dbbe_set) {
134 if ((*iter)->dbbe_active == 0)
135 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
137 error = sbuf_finish(&sbuf);
143 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
148 if (kdb_dbbe != NULL)
149 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
152 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
153 if (error != 0 || req->newptr == NULL)
157 return (kdb_dbbe_select(buf));
161 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
165 error = sysctl_wire_old_buffer(req, sizeof(int));
168 error = sysctl_handle_int(oidp, &i, 0, req);
170 if (error != 0 || req->newptr == NULL)
174 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
179 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
183 error = sysctl_wire_old_buffer(req, sizeof(int));
186 error = sysctl_handle_int(oidp, &i, 0, req);
188 if (error != 0 || req->newptr == NULL)
190 panic("kdb_sysctl_panic");
195 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
198 int *addr = (int *)0x10;
200 error = sysctl_wire_old_buffer(req, sizeof(int));
203 error = sysctl_handle_int(oidp, &i, 0, req);
205 if (error != 0 || req->newptr == NULL)
211 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
214 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
216 error = sysctl_wire_old_buffer(req, sizeof(int));
219 error = sysctl_handle_int(oidp, &i, 0, req);
221 if (error != 0 || req->newptr == NULL)
223 (*fp)(0x11111111, 0x22222222, 0x33333333);
228 kdb_panic(const char *msg)
231 printf("KDB: panic\n");
239 printf("KDB: reboot requested\n");
244 * Solaris implements a new BREAK which is initiated by a character sequence
245 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
248 * Note that this function may be called from almost anywhere, with interrupts
249 * disabled and with unknown locks held, so it must not access data other than
250 * its arguments. Its up to the caller to ensure that the state variable is
253 #define KEY_CR 13 /* CR '\r' */
254 #define KEY_TILDE 126 /* ~ */
255 #define KEY_CRTLB 2 /* ^B */
256 #define KEY_CRTLP 16 /* ^P */
257 #define KEY_CRTLR 18 /* ^R */
259 /* States of th KDB "alternate break sequence" detecting state machine. */
261 KDB_ALT_BREAK_SEEN_NONE,
262 KDB_ALT_BREAK_SEEN_CR,
263 KDB_ALT_BREAK_SEEN_CR_TILDE,
270 if (!kdb_break_to_debugger)
272 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
273 return (KDB_REQ_DEBUGGER);
277 kdb_alt_break_state(int key, int *state)
281 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
283 *state = KDB_ALT_BREAK_SEEN_CR;
289 case KDB_ALT_BREAK_SEEN_CR:
290 *state = KDB_ALT_BREAK_SEEN_NONE;
291 if (key == KEY_TILDE)
292 *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
294 case KDB_ALT_BREAK_SEEN_CR_TILDE:
295 *state = KDB_ALT_BREAK_SEEN_NONE;
296 if (key == KEY_CRTLB)
297 brk = KDB_REQ_DEBUGGER;
298 else if (key == KEY_CRTLP)
300 else if (key == KEY_CRTLR)
301 brk = KDB_REQ_REBOOT;
303 case KDB_ALT_BREAK_SEEN_NONE:
305 *state = KDB_ALT_BREAK_SEEN_NONE;
312 kdb_alt_break_internal(int key, int *state, int force_gdb)
316 if (!kdb_alt_break_to_debugger)
318 brk = kdb_alt_break_state(key, state);
320 case KDB_REQ_DEBUGGER:
322 kdb_dbbe_select("gdb");
323 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
328 kdb_dbbe_select("gdb");
329 kdb_panic("Panic sequence on console");
340 kdb_alt_break(int key, int *state)
343 return (kdb_alt_break_internal(key, state, 0));
347 * This variation on kdb_alt_break() is used only by dcons, which has its own
348 * configuration flag to force GDB use regardless of the global KDB
352 kdb_alt_break_gdb(int key, int *state)
355 return (kdb_alt_break_internal(key, state, 1));
359 * Print a backtrace of the calling thread. The backtrace is generated by
360 * the selected debugger, provided it supports backtraces. If no debugger
361 * is selected or the current debugger does not support backtraces, this
362 * function silently returns.
368 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
369 printf("KDB: stack backtrace:\n");
370 kdb_dbbe->dbbe_trace();
376 printf("KDB: stack backtrace:\n");
379 stack_print_ddb(&st);
385 * Similar to kdb_backtrace() except that it prints a backtrace of an
386 * arbitrary thread rather than the calling thread.
389 kdb_backtrace_thread(struct thread *td)
392 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
393 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
394 kdb_dbbe->dbbe_trace_thread(td);
400 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
402 stack_save_td(&st, td);
403 stack_print_ddb(&st);
409 * Set/change the current backend.
412 kdb_dbbe_select(const char *name)
414 struct kdb_dbbe *be, **iter;
416 SET_FOREACH(iter, kdb_dbbe_set) {
418 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
427 * Enter the currently selected debugger. If a message has been provided,
428 * it is printed first. If the debugger does not support the enter method,
429 * it is entered by using breakpoint(), which enters the debugger through
430 * kdb_trap(). The 'why' argument will contain a more mechanically usable
431 * string than 'msg', and is relied upon by DDB scripting to identify the
432 * reason for entering the debugger so that the right script can be run.
435 kdb_enter(const char *why, const char *msg)
438 if (kdb_dbbe != NULL && kdb_active == 0) {
440 printf("KDB: enter: %s\n", msg);
443 kdb_why = KDB_WHY_UNSET;
448 * Initialize the kernel debugger interface.
453 struct kdb_dbbe *be, **iter;
459 SET_FOREACH(iter, kdb_dbbe_set) {
461 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
462 be->dbbe_active = (pri >= 0) ? 0 : -1;
468 if (kdb_dbbe != NULL) {
469 printf("KDB: debugger backends:");
470 SET_FOREACH(iter, kdb_dbbe_set) {
472 if (be->dbbe_active == 0)
473 printf(" %s", be->dbbe_name);
476 printf("KDB: current backend: %s\n",
477 kdb_dbbe->dbbe_name);
485 kdb_jmpbuf(jmp_buf new)
498 if (!kdb_active || kdb_jmpbufp == NULL)
501 printf("KDB: reentering\n");
503 longjmp(kdb_jmpbufp, 1);
508 kdb_reenter_silent(void)
511 if (!kdb_active || kdb_jmpbufp == NULL)
514 longjmp(kdb_jmpbufp, 1);
519 * Thread-related support functions.
522 kdb_thr_ctx(struct thread *thr)
524 #if defined(SMP) && defined(KDB_STOPPEDPCB)
528 if (thr == curthread)
531 #if defined(SMP) && defined(KDB_STOPPEDPCB)
532 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
533 if (pc->pc_curthread == thr &&
534 CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
535 return (KDB_STOPPEDPCB(pc));
538 return (thr->td_pcb);
547 p = LIST_FIRST(&allproc);
549 if (p->p_flag & P_INMEM) {
550 thr = FIRST_THREAD_IN_PROC(p);
554 p = LIST_NEXT(p, p_list);
560 kdb_thr_from_pid(pid_t pid)
564 p = LIST_FIRST(&allproc);
566 if (p->p_flag & P_INMEM && p->p_pid == pid)
567 return (FIRST_THREAD_IN_PROC(p));
568 p = LIST_NEXT(p, p_list);
574 kdb_thr_lookup(lwpid_t tid)
578 thr = kdb_thr_first();
579 while (thr != NULL && thr->td_tid != tid)
580 thr = kdb_thr_next(thr);
585 kdb_thr_next(struct thread *thr)
590 thr = TAILQ_NEXT(thr, td_plist);
594 p = LIST_NEXT(p, p_list);
595 if (p != NULL && (p->p_flag & P_INMEM))
596 thr = FIRST_THREAD_IN_PROC(p);
602 kdb_thr_select(struct thread *thr)
607 kdb_thrctx = kdb_thr_ctx(thr);
612 * Enter the debugger due to a trap.
615 kdb_trap(int type, int code, struct trapframe *tf)
628 if (be == NULL || be->dbbe_trap == NULL)
631 /* We reenter the debugger through kdb_reenter(). */
635 intr = intr_disable();
638 if (!SCHEDULER_STOPPED()) {
639 other_cpus = all_cpus;
640 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
641 stop_cpus_hard(other_cpus);
651 /* Let MD code do its thing first... */
652 kdb_cpu_trap(type, code);
654 makectx(tf, &kdb_pcb);
655 kdb_thr_select(curthread);
660 handled = be->dbbe_trap(type, code);
664 if (be == NULL || be->dbbe_trap == NULL)
666 printf("Switching to %s back-end\n", be->dbbe_name);
675 restart_cpus(stopped_cpus);