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>
37 #include <sys/kernel.h>
38 #include <sys/malloc.h>
43 #include <sys/stack.h>
44 #include <sys/sysctl.h>
46 #include <machine/kdb.h>
47 #include <machine/pcb.h>
50 #include <machine/smp.h>
54 static void *kdb_jmpbufp = NULL;
55 struct kdb_dbbe *kdb_dbbe = NULL;
56 static struct pcb kdb_pcb;
57 struct pcb *kdb_thrctx = NULL;
58 struct thread *kdb_thread = NULL;
59 struct trapframe *kdb_frame = NULL;
61 #ifdef BREAK_TO_DEBUGGER
62 #define KDB_BREAK_TO_DEBUGGER 1
64 #define KDB_BREAK_TO_DEBUGGER 0
67 #ifdef ALT_BREAK_TO_DEBUGGER
68 #define KDB_ALT_BREAK_TO_DEBUGGER 1
70 #define KDB_ALT_BREAK_TO_DEBUGGER 0
73 static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
74 static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
76 KDB_BACKEND(null, NULL, NULL, NULL, NULL);
77 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
79 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
80 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
81 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
82 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
83 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
84 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
86 static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
88 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
89 0, kdb_sysctl_available, "A", "list of available KDB backends");
91 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
92 0, kdb_sysctl_current, "A", "currently selected KDB backend");
94 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
95 kdb_sysctl_enter, "I", "set to enter the debugger");
97 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
98 kdb_sysctl_panic, "I", "set to panic the kernel");
100 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
101 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
103 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
104 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
106 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger, CTLTYPE_INT | CTLFLAG_RW |
107 CTLFLAG_TUN, &kdb_break_to_debugger, 0, "Enable break to debugger");
108 TUNABLE_INT("debug.kdb.break_to_debugger", &kdb_break_to_debugger);
110 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger, CTLTYPE_INT |
111 CTLFLAG_RW | CTLFLAG_TUN, &kdb_alt_break_to_debugger, 0,
112 "Enable alternative break to debugger");
113 TUNABLE_INT("debug.kdb.alt_break_to_debugger", &kdb_alt_break_to_debugger);
116 * Flag to indicate to debuggers why the debugger was entered.
118 const char * volatile kdb_why = KDB_WHY_UNSET;
121 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
123 struct kdb_dbbe **iter;
127 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
128 SET_FOREACH(iter, kdb_dbbe_set) {
129 if ((*iter)->dbbe_active == 0)
130 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
132 error = sbuf_finish(&sbuf);
138 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
143 if (kdb_dbbe != NULL)
144 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
147 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
148 if (error != 0 || req->newptr == NULL)
152 return (kdb_dbbe_select(buf));
156 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
160 error = sysctl_wire_old_buffer(req, sizeof(int));
163 error = sysctl_handle_int(oidp, &i, 0, req);
165 if (error != 0 || req->newptr == NULL)
169 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
174 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
178 error = sysctl_wire_old_buffer(req, sizeof(int));
181 error = sysctl_handle_int(oidp, &i, 0, req);
183 if (error != 0 || req->newptr == NULL)
185 panic("kdb_sysctl_panic");
190 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
193 int *addr = (int *)0x10;
195 error = sysctl_wire_old_buffer(req, sizeof(int));
198 error = sysctl_handle_int(oidp, &i, 0, req);
200 if (error != 0 || req->newptr == NULL)
206 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
209 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
211 error = sysctl_wire_old_buffer(req, sizeof(int));
214 error = sysctl_handle_int(oidp, &i, 0, req);
216 if (error != 0 || req->newptr == NULL)
218 (*fp)(0x11111111, 0x22222222, 0x33333333);
223 kdb_panic(const char *msg)
226 printf("KDB: panic\n");
234 printf("KDB: reboot requested\n");
239 * Solaris implements a new BREAK which is initiated by a character sequence
240 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
243 * Note that this function may be called from almost anywhere, with interrupts
244 * disabled and with unknown locks held, so it must not access data other than
245 * its arguments. Its up to the caller to ensure that the state variable is
249 #define KEY_CR 13 /* CR '\r' */
250 #define KEY_TILDE 126 /* ~ */
251 #define KEY_CRTLB 2 /* ^B */
252 #define KEY_CRTLP 16 /* ^P */
253 #define KEY_CRTLR 18 /* ^R */
255 /* States of th KDB "alternate break sequence" detecting state machine. */
257 KDB_ALT_BREAK_SEEN_NONE,
258 KDB_ALT_BREAK_SEEN_CR,
259 KDB_ALT_BREAK_SEEN_CR_TILDE,
266 if (!kdb_break_to_debugger)
268 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
269 return (KDB_REQ_DEBUGGER);
273 kdb_alt_break_state(int key, int *state)
277 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
279 *state = KDB_ALT_BREAK_SEEN_CR;
285 case KDB_ALT_BREAK_SEEN_CR:
286 *state = KDB_ALT_BREAK_SEEN_NONE;
287 if (key == KEY_TILDE)
288 *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
290 case KDB_ALT_BREAK_SEEN_CR_TILDE:
291 *state = KDB_ALT_BREAK_SEEN_NONE;
292 if (key == KEY_CRTLB)
293 brk = KDB_REQ_DEBUGGER;
294 else if (key == KEY_CRTLP)
296 else if (key == KEY_CRTLR)
297 brk = KDB_REQ_REBOOT;
299 case KDB_ALT_BREAK_SEEN_NONE:
301 *state = KDB_ALT_BREAK_SEEN_NONE;
308 kdb_alt_break_internal(int key, int *state, int force_gdb)
312 if (!kdb_alt_break_to_debugger)
314 brk = kdb_alt_break_state(key, state);
316 case KDB_REQ_DEBUGGER:
318 kdb_dbbe_select("gdb");
319 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
324 kdb_dbbe_select("gdb");
325 kdb_panic("Panic sequence on console");
336 kdb_alt_break(int key, int *state)
339 return (kdb_alt_break_internal(key, state, 0));
343 * This variation on kdb_alt_break() is used only by dcons, which has its own
344 * configuration flag to force GDB use regardless of the global KDB
348 kdb_alt_break_gdb(int key, int *state)
351 return (kdb_alt_break_internal(key, state, 1));
355 * Print a backtrace of the calling thread. The backtrace is generated by
356 * the selected debugger, provided it supports backtraces. If no debugger
357 * is selected or the current debugger does not support backtraces, this
358 * function silently returns.
365 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
366 printf("KDB: stack backtrace:\n");
367 kdb_dbbe->dbbe_trace();
373 printf("KDB: stack backtrace:\n");
376 stack_print_ddb(&st);
382 * Similar to kdb_backtrace() except that it prints a backtrace of an
383 * arbitrary thread rather than the calling thread.
386 kdb_backtrace_thread(struct thread *td)
389 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
390 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
391 kdb_dbbe->dbbe_trace_thread(td);
397 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
399 stack_save_td(&st, td);
400 stack_print_ddb(&st);
406 * Set/change the current backend.
410 kdb_dbbe_select(const char *name)
412 struct kdb_dbbe *be, **iter;
414 SET_FOREACH(iter, kdb_dbbe_set) {
416 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
425 * Enter the currently selected debugger. If a message has been provided,
426 * it is printed first. If the debugger does not support the enter method,
427 * it is entered by using breakpoint(), which enters the debugger through
428 * kdb_trap(). The 'why' argument will contain a more mechanically usable
429 * string than 'msg', and is relied upon by DDB scripting to identify the
430 * reason for entering the debugger so that the right script can be run.
433 kdb_enter(const char *why, const char *msg)
436 if (kdb_dbbe != NULL && kdb_active == 0) {
438 printf("KDB: enter: %s\n", msg);
441 kdb_why = KDB_WHY_UNSET;
446 * Initialize the kernel debugger interface.
452 struct kdb_dbbe *be, **iter;
458 SET_FOREACH(iter, kdb_dbbe_set) {
460 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
461 be->dbbe_active = (pri >= 0) ? 0 : -1;
467 if (kdb_dbbe != NULL) {
468 printf("KDB: debugger backends:");
469 SET_FOREACH(iter, kdb_dbbe_set) {
471 if (be->dbbe_active == 0)
472 printf(" %s", be->dbbe_name);
475 printf("KDB: current backend: %s\n",
476 kdb_dbbe->dbbe_name);
485 kdb_jmpbuf(jmp_buf new)
498 if (!kdb_active || kdb_jmpbufp == NULL)
501 longjmp(kdb_jmpbufp, 1);
506 * Thread related support functions.
510 kdb_thr_ctx(struct thread *thr)
512 #if defined(SMP) && defined(KDB_STOPPEDPCB)
516 if (thr == curthread)
519 #if defined(SMP) && defined(KDB_STOPPEDPCB)
520 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
521 if (pc->pc_curthread == thr &&
522 CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
523 return (KDB_STOPPEDPCB(pc));
526 return (thr->td_pcb);
535 p = LIST_FIRST(&allproc);
537 if (p->p_flag & P_INMEM) {
538 thr = FIRST_THREAD_IN_PROC(p);
542 p = LIST_NEXT(p, p_list);
548 kdb_thr_from_pid(pid_t pid)
552 p = LIST_FIRST(&allproc);
554 if (p->p_flag & P_INMEM && p->p_pid == pid)
555 return (FIRST_THREAD_IN_PROC(p));
556 p = LIST_NEXT(p, p_list);
562 kdb_thr_lookup(lwpid_t tid)
566 thr = kdb_thr_first();
567 while (thr != NULL && thr->td_tid != tid)
568 thr = kdb_thr_next(thr);
573 kdb_thr_next(struct thread *thr)
578 thr = TAILQ_NEXT(thr, td_plist);
582 p = LIST_NEXT(p, p_list);
583 if (p != NULL && (p->p_flag & P_INMEM))
584 thr = FIRST_THREAD_IN_PROC(p);
590 kdb_thr_select(struct thread *thr)
595 kdb_thrctx = kdb_thr_ctx(thr);
600 * Enter the debugger due to a trap.
604 kdb_trap(int type, int code, struct trapframe *tf)
617 if (be == NULL || be->dbbe_trap == NULL)
620 /* We reenter the debugger through kdb_reenter(). */
624 intr = intr_disable();
627 if (!SCHEDULER_STOPPED()) {
628 other_cpus = all_cpus;
629 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
630 stop_cpus_hard(other_cpus);
640 /* Let MD code do its thing first... */
641 kdb_cpu_trap(type, code);
643 makectx(tf, &kdb_pcb);
644 kdb_thr_select(curthread);
649 handled = be->dbbe_trap(type, code);
653 if (be == NULL || be->dbbe_trap == NULL)
655 printf("Switching to %s back-end\n", be->dbbe_name);
664 restart_cpus(stopped_cpus);