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>
41 #include <sys/stack.h>
42 #include <sys/sysctl.h>
44 #include <machine/kdb.h>
45 #include <machine/pcb.h>
48 #include <machine/smp.h>
52 static void *kdb_jmpbufp = NULL;
53 struct kdb_dbbe *kdb_dbbe = NULL;
54 static struct pcb kdb_pcb;
55 struct pcb *kdb_thrctx = NULL;
56 struct thread *kdb_thread = NULL;
57 struct trapframe *kdb_frame = NULL;
59 #ifdef BREAK_TO_DEBUGGER
60 #define KDB_BREAK_TO_DEBUGGER 1
62 #define KDB_BREAK_TO_DEBUGGER 0
65 #ifdef ALT_BREAK_TO_DEBUGGER
66 #define KDB_ALT_BREAK_TO_DEBUGGER 1
68 #define KDB_ALT_BREAK_TO_DEBUGGER 0
71 static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
72 static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
74 KDB_BACKEND(null, NULL, NULL, NULL, NULL);
75 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
77 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
78 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
79 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
80 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
81 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
82 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
84 SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
86 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
87 0, kdb_sysctl_available, "A", "list of available KDB backends");
89 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
90 0, kdb_sysctl_current, "A", "currently selected KDB backend");
92 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
93 kdb_sysctl_enter, "I", "set to enter the debugger");
95 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
96 kdb_sysctl_panic, "I", "set to panic the kernel");
98 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
99 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
101 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
102 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
104 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger, CTLTYPE_INT | CTLFLAG_RW |
105 CTLFLAG_TUN, &kdb_break_to_debugger, 0, "Enable break to debugger");
106 TUNABLE_INT("debug.kdb.break_to_debugger", &kdb_break_to_debugger);
108 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger, CTLTYPE_INT |
109 CTLFLAG_RW | CTLFLAG_TUN, &kdb_alt_break_to_debugger, 0,
110 "Enable alternative break to debugger");
111 TUNABLE_INT("debug.kdb.alt_break_to_debugger", &kdb_alt_break_to_debugger);
114 * Flag indicating whether or not to IPI the other CPUs to stop them on
115 * entering the debugger. Sometimes, this will result in a deadlock as
116 * stop_cpus() waits for the other cpus to stop, so we allow it to be
117 * disabled. In order to maximize the chances of success, use a hard
121 static int kdb_stop_cpus = 1;
122 SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLFLAG_RW | CTLFLAG_TUN,
123 &kdb_stop_cpus, 0, "stop other CPUs when entering the debugger");
124 TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus);
128 * Flag to indicate to debuggers why the debugger was entered.
130 const char * volatile kdb_why = KDB_WHY_UNSET;
133 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
135 struct kdb_dbbe *be, **iter;
141 SET_FOREACH(iter, kdb_dbbe_set) {
143 if (be->dbbe_active == 0)
144 sz += strlen(be->dbbe_name) + 1;
147 avail = malloc(sz, M_TEMP, M_WAITOK);
151 SET_FOREACH(iter, kdb_dbbe_set) {
153 if (be->dbbe_active == 0) {
154 len = snprintf(p, sz, "%s ", be->dbbe_name);
159 KASSERT(sz >= 0, ("%s", __func__));
160 error = sysctl_handle_string(oidp, avail, 0, req);
166 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
171 if (kdb_dbbe != NULL)
172 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
175 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
176 if (error != 0 || req->newptr == NULL)
180 return (kdb_dbbe_select(buf));
184 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
188 error = sysctl_wire_old_buffer(req, sizeof(int));
191 error = sysctl_handle_int(oidp, &i, 0, req);
193 if (error != 0 || req->newptr == NULL)
197 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
202 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
206 error = sysctl_wire_old_buffer(req, sizeof(int));
209 error = sysctl_handle_int(oidp, &i, 0, req);
211 if (error != 0 || req->newptr == NULL)
213 panic("kdb_sysctl_panic");
218 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
221 int *addr = (int *)0x10;
223 error = sysctl_wire_old_buffer(req, sizeof(int));
226 error = sysctl_handle_int(oidp, &i, 0, req);
228 if (error != 0 || req->newptr == NULL)
234 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
237 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
239 error = sysctl_wire_old_buffer(req, sizeof(int));
242 error = sysctl_handle_int(oidp, &i, 0, req);
244 if (error != 0 || req->newptr == NULL)
246 (*fp)(0x11111111, 0x22222222, 0x33333333);
251 kdb_panic(const char *msg)
254 printf("KDB: panic\n");
262 printf("KDB: reboot requested\n");
267 * Solaris implements a new BREAK which is initiated by a character sequence
268 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
271 * Note that this function may be called from almost anywhere, with interrupts
272 * disabled and with unknown locks held, so it must not access data other than
273 * its arguments. Its up to the caller to ensure that the state variable is
277 #define KEY_CR 13 /* CR '\r' */
278 #define KEY_TILDE 126 /* ~ */
279 #define KEY_CRTLB 2 /* ^B */
280 #define KEY_CRTLP 16 /* ^P */
281 #define KEY_CRTLR 18 /* ^R */
287 if (!kdb_break_to_debugger)
289 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
290 return (KDB_REQ_DEBUGGER);
294 kdb_alt_break_state(int key, int *state)
305 if (key == KEY_TILDE)
309 if (key == KEY_CRTLB)
310 brk = KDB_REQ_DEBUGGER;
311 else if (key == KEY_CRTLP)
313 else if (key == KEY_CRTLR)
314 brk = KDB_REQ_REBOOT;
321 kdb_alt_break_internal(int key, int *state, int force_gdb)
325 if (!kdb_alt_break_to_debugger)
327 brk = kdb_alt_break_state(key, state);
329 case KDB_REQ_DEBUGGER:
331 kdb_dbbe_select("gdb");
332 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
337 kdb_dbbe_select("gdb");
338 kdb_panic("Panic sequence on console");
349 kdb_alt_break(int key, int *state)
352 return (kdb_alt_break_internal(key, state, 0));
356 * This variation on kdb_alt_break() is used only by dcons, which has its own
357 * configuration flag to force GDB use regardless of the global KDB
361 kdb_alt_break_gdb(int key, int *state)
364 return (kdb_alt_break_internal(key, state, 1));
368 * Print a backtrace of the calling thread. The backtrace is generated by
369 * the selected debugger, provided it supports backtraces. If no debugger
370 * is selected or the current debugger does not support backtraces, this
371 * function silently returns.
378 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
379 printf("KDB: stack backtrace:\n");
380 kdb_dbbe->dbbe_trace();
386 printf("KDB: stack backtrace:\n");
389 stack_print_ddb(&st);
395 * Similar to kdb_backtrace() except that it prints a backtrace of an
396 * arbitrary thread rather than the calling thread.
399 kdb_backtrace_thread(struct thread *td)
402 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
403 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
404 kdb_dbbe->dbbe_trace_thread(td);
410 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
412 stack_save_td(&st, td);
413 stack_print_ddb(&st);
419 * Set/change the current backend.
423 kdb_dbbe_select(const char *name)
425 struct kdb_dbbe *be, **iter;
427 SET_FOREACH(iter, kdb_dbbe_set) {
429 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
438 * Enter the currently selected debugger. If a message has been provided,
439 * it is printed first. If the debugger does not support the enter method,
440 * it is entered by using breakpoint(), which enters the debugger through
441 * kdb_trap(). The 'why' argument will contain a more mechanically usable
442 * string than 'msg', and is relied upon by DDB scripting to identify the
443 * reason for entering the debugger so that the right script can be run.
446 kdb_enter(const char *why, const char *msg)
449 if (kdb_dbbe != NULL && kdb_active == 0) {
451 printf("KDB: enter: %s\n", msg);
454 kdb_why = KDB_WHY_UNSET;
459 * Initialize the kernel debugger interface.
465 struct kdb_dbbe *be, **iter;
471 SET_FOREACH(iter, kdb_dbbe_set) {
473 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
474 be->dbbe_active = (pri >= 0) ? 0 : -1;
480 if (kdb_dbbe != NULL) {
481 printf("KDB: debugger backends:");
482 SET_FOREACH(iter, kdb_dbbe_set) {
484 if (be->dbbe_active == 0)
485 printf(" %s", be->dbbe_name);
488 printf("KDB: current backend: %s\n",
489 kdb_dbbe->dbbe_name);
498 kdb_jmpbuf(jmp_buf new)
511 if (!kdb_active || kdb_jmpbufp == NULL)
514 longjmp(kdb_jmpbufp, 1);
519 * Thread related support functions.
523 kdb_thr_ctx(struct thread *thr)
525 #if defined(SMP) && defined(KDB_STOPPEDPCB)
529 if (thr == curthread)
532 #if defined(SMP) && defined(KDB_STOPPEDPCB)
533 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
534 if (pc->pc_curthread == thr && (stopped_cpus & pc->pc_cpumask))
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.
616 kdb_trap(int type, int code, struct trapframe *tf)
626 if (be == NULL || be->dbbe_trap == NULL)
629 /* We reenter the debugger through kdb_reenter(). */
633 intr = intr_disable();
636 if (!SCHEDULER_STOPPED()) {
637 if ((did_stop_cpus = kdb_stop_cpus) != 0)
638 stop_cpus_hard(PCPU_GET(other_cpus));
647 /* Let MD code do its thing first... */
648 kdb_cpu_trap(type, code);
650 makectx(tf, &kdb_pcb);
651 kdb_thr_select(curthread);
654 handled = be->dbbe_trap(type, code);
658 if (be == NULL || be->dbbe_trap == NULL)
660 printf("Switching to %s back-end\n", be->dbbe_name);
667 restart_cpus(stopped_cpus);