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"
32 #include "opt_watchdog.h"
34 #include <sys/param.h>
35 #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 <sys/watchdog.h>
49 #include <machine/kdb.h>
50 #include <machine/pcb.h>
53 #include <machine/smp.h>
57 static void *kdb_jmpbufp = NULL;
58 struct kdb_dbbe *kdb_dbbe = NULL;
59 static struct pcb kdb_pcb;
60 struct pcb *kdb_thrctx = NULL;
61 struct thread *kdb_thread = NULL;
62 struct trapframe *kdb_frame = NULL;
64 #ifdef BREAK_TO_DEBUGGER
65 #define KDB_BREAK_TO_DEBUGGER 1
67 #define KDB_BREAK_TO_DEBUGGER 0
70 #ifdef ALT_BREAK_TO_DEBUGGER
71 #define KDB_ALT_BREAK_TO_DEBUGGER 1
73 #define KDB_ALT_BREAK_TO_DEBUGGER 0
76 static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
77 static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
79 KDB_BACKEND(null, NULL, NULL, NULL);
80 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
82 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
83 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
84 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
85 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
86 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
87 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
89 SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
91 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
92 0, kdb_sysctl_available, "A", "list of available KDB backends");
94 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
95 0, kdb_sysctl_current, "A", "currently selected KDB backend");
97 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
98 kdb_sysctl_enter, "I", "set to enter the debugger");
100 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
101 kdb_sysctl_panic, "I", "set to panic the kernel");
103 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
104 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
106 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code, CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
107 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
109 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger, CTLTYPE_INT | CTLFLAG_RW |
110 CTLFLAG_TUN, &kdb_break_to_debugger, 0, "Enable break to debugger");
111 TUNABLE_INT("debug.kdb.break_to_debugger", &kdb_break_to_debugger);
113 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger, CTLTYPE_INT |
114 CTLFLAG_RW | CTLFLAG_TUN, &kdb_alt_break_to_debugger, 0,
115 "Enable alternative break to debugger");
116 TUNABLE_INT("debug.kdb.alt_break_to_debugger", &kdb_alt_break_to_debugger);
119 * Flag to indicate to debuggers why the debugger was entered.
121 const char * volatile kdb_why = KDB_WHY_UNSET;
124 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
126 struct kdb_dbbe **iter;
130 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
131 SET_FOREACH(iter, kdb_dbbe_set) {
132 if ((*iter)->dbbe_active == 0)
133 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
135 error = sbuf_finish(&sbuf);
141 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
146 if (kdb_dbbe != NULL)
147 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
150 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
151 if (error != 0 || req->newptr == NULL)
155 return (kdb_dbbe_select(buf));
159 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
163 error = sysctl_wire_old_buffer(req, sizeof(int));
166 error = sysctl_handle_int(oidp, &i, 0, req);
168 if (error != 0 || req->newptr == NULL)
172 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
177 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
181 error = sysctl_wire_old_buffer(req, sizeof(int));
184 error = sysctl_handle_int(oidp, &i, 0, req);
186 if (error != 0 || req->newptr == NULL)
188 panic("kdb_sysctl_panic");
193 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
196 int *addr = (int *)0x10;
198 error = sysctl_wire_old_buffer(req, sizeof(int));
201 error = sysctl_handle_int(oidp, &i, 0, req);
203 if (error != 0 || req->newptr == NULL)
209 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
212 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
214 error = sysctl_wire_old_buffer(req, sizeof(int));
217 error = sysctl_handle_int(oidp, &i, 0, req);
219 if (error != 0 || req->newptr == NULL)
221 (*fp)(0x11111111, 0x22222222, 0x33333333);
226 kdb_panic(const char *msg)
231 other_cpus = all_cpus;
232 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
233 stop_cpus_hard(other_cpus);
235 printf("KDB: panic\n");
243 printf("KDB: reboot requested\n");
248 * Solaris implements a new BREAK which is initiated by a character sequence
249 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
252 * Note that this function may be called from almost anywhere, with interrupts
253 * disabled and with unknown locks held, so it must not access data other than
254 * its arguments. Its up to the caller to ensure that the state variable is
258 #define KEY_CR 13 /* CR '\r' */
259 #define KEY_TILDE 126 /* ~ */
260 #define KEY_CRTLB 2 /* ^B */
261 #define KEY_CRTLP 16 /* ^P */
262 #define KEY_CRTLR 18 /* ^R */
264 /* States of th KDB "alternate break sequence" detecting state machine. */
266 KDB_ALT_BREAK_SEEN_NONE,
267 KDB_ALT_BREAK_SEEN_CR,
268 KDB_ALT_BREAK_SEEN_CR_TILDE,
275 if (!kdb_break_to_debugger)
277 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
278 return (KDB_REQ_DEBUGGER);
282 kdb_alt_break_state(int key, int *state)
286 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
288 *state = KDB_ALT_BREAK_SEEN_CR;
294 case KDB_ALT_BREAK_SEEN_CR:
295 *state = KDB_ALT_BREAK_SEEN_NONE;
296 if (key == KEY_TILDE)
297 *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
299 case KDB_ALT_BREAK_SEEN_CR_TILDE:
300 *state = KDB_ALT_BREAK_SEEN_NONE;
301 if (key == KEY_CRTLB)
302 brk = KDB_REQ_DEBUGGER;
303 else if (key == KEY_CRTLP)
305 else if (key == KEY_CRTLR)
306 brk = KDB_REQ_REBOOT;
308 case KDB_ALT_BREAK_SEEN_NONE:
310 *state = KDB_ALT_BREAK_SEEN_NONE;
317 kdb_alt_break_internal(int key, int *state, int force_gdb)
321 if (!kdb_alt_break_to_debugger)
323 brk = kdb_alt_break_state(key, state);
325 case KDB_REQ_DEBUGGER:
327 kdb_dbbe_select("gdb");
328 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
333 kdb_dbbe_select("gdb");
334 kdb_panic("Panic sequence on console");
345 kdb_alt_break(int key, int *state)
348 return (kdb_alt_break_internal(key, state, 0));
352 * This variation on kdb_alt_break() is used only by dcons, which has its own
353 * configuration flag to force GDB use regardless of the global KDB
357 kdb_alt_break_gdb(int key, int *state)
360 return (kdb_alt_break_internal(key, state, 1));
364 * Print a backtrace of the calling thread. The backtrace is generated by
365 * the selected debugger, provided it supports backtraces. If no debugger
366 * is selected or the current debugger does not support backtraces, this
367 * function silently returns.
374 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
375 printf("KDB: stack backtrace:\n");
376 kdb_dbbe->dbbe_trace();
382 printf("KDB: stack backtrace:\n");
384 stack_print_ddb(&st);
390 * Set/change the current backend.
394 kdb_dbbe_select(const char *name)
396 struct kdb_dbbe *be, **iter;
398 SET_FOREACH(iter, kdb_dbbe_set) {
400 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
409 * Enter the currently selected debugger. If a message has been provided,
410 * it is printed first. If the debugger does not support the enter method,
411 * it is entered by using breakpoint(), which enters the debugger through
412 * kdb_trap(). The 'why' argument will contain a more mechanically usable
413 * string than 'msg', and is relied upon by DDB scripting to identify the
414 * reason for entering the debugger so that the right script can be run.
417 kdb_enter(const char *why, const char *msg)
420 if (kdb_dbbe != NULL && kdb_active == 0) {
422 printf("KDB: enter: %s\n", msg);
425 kdb_why = KDB_WHY_UNSET;
430 * Initialize the kernel debugger interface.
436 struct kdb_dbbe *be, **iter;
442 SET_FOREACH(iter, kdb_dbbe_set) {
444 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
445 be->dbbe_active = (pri >= 0) ? 0 : -1;
451 if (kdb_dbbe != NULL) {
452 printf("KDB: debugger backends:");
453 SET_FOREACH(iter, kdb_dbbe_set) {
455 if (be->dbbe_active == 0)
456 printf(" %s", be->dbbe_name);
459 printf("KDB: current backend: %s\n",
460 kdb_dbbe->dbbe_name);
469 kdb_jmpbuf(jmp_buf new)
482 if (!kdb_active || kdb_jmpbufp == NULL)
485 longjmp(kdb_jmpbufp, 1);
490 * Thread related support functions.
494 kdb_thr_ctx(struct thread *thr)
496 #if defined(SMP) && defined(KDB_STOPPEDPCB)
500 if (thr == curthread)
503 #if defined(SMP) && defined(KDB_STOPPEDPCB)
504 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
505 if (pc->pc_curthread == thr &&
506 CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
507 return (KDB_STOPPEDPCB(pc));
510 return (thr->td_pcb);
519 p = LIST_FIRST(&allproc);
521 if (p->p_flag & P_INMEM) {
522 thr = FIRST_THREAD_IN_PROC(p);
526 p = LIST_NEXT(p, p_list);
532 kdb_thr_from_pid(pid_t pid)
536 p = LIST_FIRST(&allproc);
538 if (p->p_flag & P_INMEM && p->p_pid == pid)
539 return (FIRST_THREAD_IN_PROC(p));
540 p = LIST_NEXT(p, p_list);
546 kdb_thr_lookup(lwpid_t tid)
550 thr = kdb_thr_first();
551 while (thr != NULL && thr->td_tid != tid)
552 thr = kdb_thr_next(thr);
557 kdb_thr_next(struct thread *thr)
562 thr = TAILQ_NEXT(thr, td_plist);
566 p = LIST_NEXT(p, p_list);
567 if (p != NULL && (p->p_flag & P_INMEM))
568 thr = FIRST_THREAD_IN_PROC(p);
574 kdb_thr_select(struct thread *thr)
579 kdb_thrctx = kdb_thr_ctx(thr);
584 * Enter the debugger due to a trap.
588 kdb_trap(int type, int code, struct trapframe *tf)
601 if (be == NULL || be->dbbe_trap == NULL)
604 /* We reenter the debugger through kdb_reenter(). */
608 intr = intr_disable();
611 wdoglvt = wdog_kern_last_timeout();
612 wdog_kern_pat(WD_TO_NEVER);
615 other_cpus = all_cpus;
616 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
617 stop_cpus_hard(other_cpus);
624 /* Let MD code do its thing first... */
625 kdb_cpu_trap(type, code);
627 makectx(tf, &kdb_pcb);
628 kdb_thr_select(curthread);
631 handled = be->dbbe_trap(type, code);
635 if (be == NULL || be->dbbe_trap == NULL)
637 printf("Switching to %s back-end\n", be->dbbe_name);
643 restart_cpus(stopped_cpus);
646 wdog_kern_pat(wdoglvt);