2 * Copyright (c) 2004 The FreeBSD Project
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
31 #include "opt_stack.h"
33 #include <sys/param.h>
34 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/malloc.h>
42 #include <sys/stack.h>
43 #include <sys/sysctl.h>
45 #include <machine/kdb.h>
46 #include <machine/pcb.h>
49 #include <machine/smp.h>
53 static void *kdb_jmpbufp = NULL;
54 struct kdb_dbbe *kdb_dbbe = NULL;
55 static struct pcb kdb_pcb;
56 struct pcb *kdb_thrctx = NULL;
57 struct thread *kdb_thread = NULL;
58 struct trapframe *kdb_frame = NULL;
60 KDB_BACKEND(null, NULL, NULL, NULL);
61 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
63 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
64 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
65 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
66 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
67 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
68 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
70 SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
72 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
73 0, kdb_sysctl_available, "A", "list of available KDB backends");
75 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
76 0, kdb_sysctl_current, "A", "currently selected KDB backend");
78 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
79 kdb_sysctl_enter, "I", "set to enter the debugger");
81 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
82 kdb_sysctl_panic, "I", "set to panic the kernel");
84 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
85 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
87 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
88 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
91 * Flag indicating whether or not to IPI the other CPUs to stop them on
92 * entering the debugger. Sometimes, this will result in a deadlock as
93 * stop_cpus() waits for the other cpus to stop, so we allow it to be
94 * disabled. In order to maximize the chances of success, use a hard
98 static int kdb_stop_cpus = 1;
99 SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLFLAG_RW | CTLFLAG_TUN,
100 &kdb_stop_cpus, 0, "stop other CPUs when entering the debugger");
101 TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus);
105 * Flag to indicate to debuggers why the debugger was entered.
107 const char * volatile kdb_why = KDB_WHY_UNSET;
110 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
112 struct kdb_dbbe **iter;
116 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
117 SET_FOREACH(iter, kdb_dbbe_set) {
118 if ((*iter)->dbbe_active == 0)
119 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
121 error = sbuf_finish(&sbuf);
127 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
132 if (kdb_dbbe != NULL)
133 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
136 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
137 if (error != 0 || req->newptr == NULL)
141 return (kdb_dbbe_select(buf));
145 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
149 error = sysctl_wire_old_buffer(req, sizeof(int));
152 error = sysctl_handle_int(oidp, &i, 0, req);
154 if (error != 0 || req->newptr == NULL)
158 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
163 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
167 error = sysctl_wire_old_buffer(req, sizeof(int));
170 error = sysctl_handle_int(oidp, &i, 0, req);
172 if (error != 0 || req->newptr == NULL)
174 panic("kdb_sysctl_panic");
179 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
182 int *addr = (int *)0x10;
184 error = sysctl_wire_old_buffer(req, sizeof(int));
187 error = sysctl_handle_int(oidp, &i, 0, req);
189 if (error != 0 || req->newptr == NULL)
195 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
198 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
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)
207 (*fp)(0x11111111, 0x22222222, 0x33333333);
212 kdb_panic(const char *msg)
216 stop_cpus_hard(PCPU_GET(other_cpus));
218 printf("KDB: panic\n");
226 printf("KDB: reboot requested\n");
231 * Solaris implements a new BREAK which is initiated by a character sequence
232 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
235 * Note that this function may be called from almost anywhere, with interrupts
236 * disabled and with unknown locks held, so it must not access data other than
237 * its arguments. Its up to the caller to ensure that the state variable is
241 #define KEY_CR 13 /* CR '\r' */
242 #define KEY_TILDE 126 /* ~ */
243 #define KEY_CRTLB 2 /* ^B */
244 #define KEY_CRTLP 16 /* ^P */
245 #define KEY_CRTLR 18 /* ^R */
247 /* States of th KDB "alternate break sequence" detecting state machine. */
249 KDB_ALT_BREAK_SEEN_NONE,
250 KDB_ALT_BREAK_SEEN_CR,
251 KDB_ALT_BREAK_SEEN_CR_TILDE,
255 kdb_alt_break(int key, int *state)
259 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
261 *state = KDB_ALT_BREAK_SEEN_CR;
267 case KDB_ALT_BREAK_SEEN_CR:
268 *state = KDB_ALT_BREAK_SEEN_NONE;
269 if (key == KEY_TILDE)
270 *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
272 case KDB_ALT_BREAK_SEEN_CR_TILDE:
273 *state = KDB_ALT_BREAK_SEEN_NONE;
274 if (key == KEY_CRTLB)
275 brk = KDB_REQ_DEBUGGER;
276 else if (key == KEY_CRTLP)
278 else if (key == KEY_CRTLR)
279 brk = KDB_REQ_REBOOT;
281 case KDB_ALT_BREAK_SEEN_NONE:
283 *state = KDB_ALT_BREAK_SEEN_NONE;
290 * Print a backtrace of the calling thread. The backtrace is generated by
291 * the selected debugger, provided it supports backtraces. If no debugger
292 * is selected or the current debugger does not support backtraces, this
293 * function silently returns.
300 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
301 printf("KDB: stack backtrace:\n");
302 kdb_dbbe->dbbe_trace();
308 printf("KDB: stack backtrace:\n");
310 stack_print_ddb(&st);
316 * Set/change the current backend.
320 kdb_dbbe_select(const char *name)
322 struct kdb_dbbe *be, **iter;
324 SET_FOREACH(iter, kdb_dbbe_set) {
326 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
335 * Enter the currently selected debugger. If a message has been provided,
336 * it is printed first. If the debugger does not support the enter method,
337 * it is entered by using breakpoint(), which enters the debugger through
338 * kdb_trap(). The 'why' argument will contain a more mechanically usable
339 * string than 'msg', and is relied upon by DDB scripting to identify the
340 * reason for entering the debugger so that the right script can be run.
343 kdb_enter(const char *why, const char *msg)
346 if (kdb_dbbe != NULL && kdb_active == 0) {
348 printf("KDB: enter: %s\n", msg);
351 kdb_why = KDB_WHY_UNSET;
356 * Initialize the kernel debugger interface.
362 struct kdb_dbbe *be, **iter;
368 SET_FOREACH(iter, kdb_dbbe_set) {
370 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
371 be->dbbe_active = (pri >= 0) ? 0 : -1;
377 if (kdb_dbbe != NULL) {
378 printf("KDB: debugger backends:");
379 SET_FOREACH(iter, kdb_dbbe_set) {
381 if (be->dbbe_active == 0)
382 printf(" %s", be->dbbe_name);
385 printf("KDB: current backend: %s\n",
386 kdb_dbbe->dbbe_name);
395 kdb_jmpbuf(jmp_buf new)
408 if (!kdb_active || kdb_jmpbufp == NULL)
411 longjmp(kdb_jmpbufp, 1);
416 * Thread related support functions.
420 kdb_thr_ctx(struct thread *thr)
422 #if defined(SMP) && defined(KDB_STOPPEDPCB)
426 if (thr == curthread)
429 #if defined(SMP) && defined(KDB_STOPPEDPCB)
430 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
431 if (pc->pc_curthread == thr &&
432 CPU_OVERLAP(&stopped_cpus, &pc->pc_cpumask))
433 return (KDB_STOPPEDPCB(pc));
436 return (thr->td_pcb);
445 p = LIST_FIRST(&allproc);
447 if (p->p_flag & P_INMEM) {
448 thr = FIRST_THREAD_IN_PROC(p);
452 p = LIST_NEXT(p, p_list);
458 kdb_thr_from_pid(pid_t pid)
462 p = LIST_FIRST(&allproc);
464 if (p->p_flag & P_INMEM && p->p_pid == pid)
465 return (FIRST_THREAD_IN_PROC(p));
466 p = LIST_NEXT(p, p_list);
472 kdb_thr_lookup(lwpid_t tid)
476 thr = kdb_thr_first();
477 while (thr != NULL && thr->td_tid != tid)
478 thr = kdb_thr_next(thr);
483 kdb_thr_next(struct thread *thr)
488 thr = TAILQ_NEXT(thr, td_plist);
492 p = LIST_NEXT(p, p_list);
493 if (p != NULL && (p->p_flag & P_INMEM))
494 thr = FIRST_THREAD_IN_PROC(p);
500 kdb_thr_select(struct thread *thr)
505 kdb_thrctx = kdb_thr_ctx(thr);
510 * Enter the debugger due to a trap.
514 kdb_trap(int type, int code, struct trapframe *tf)
524 if (be == NULL || be->dbbe_trap == NULL)
527 /* We reenter the debugger through kdb_reenter(). */
531 intr = intr_disable();
534 if ((did_stop_cpus = kdb_stop_cpus) != 0)
535 stop_cpus_hard(PCPU_GET(other_cpus));
542 /* Let MD code do its thing first... */
543 kdb_cpu_trap(type, code);
545 makectx(tf, &kdb_pcb);
546 kdb_thr_select(curthread);
549 handled = be->dbbe_trap(type, code);
553 if (be == NULL || be->dbbe_trap == NULL)
555 printf("Switching to %s back-end\n", be->dbbe_name);
562 restart_cpus(stopped_cpus);