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 #ifdef BREAK_TO_DEBUGGER
61 #define KDB_BREAK_TO_DEBUGGER 1
63 #define KDB_BREAK_TO_DEBUGGER 0
66 #ifdef ALT_BREAK_TO_DEBUGGER
67 #define KDB_ALT_BREAK_TO_DEBUGGER 1
69 #define KDB_ALT_BREAK_TO_DEBUGGER 0
72 static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
73 static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
75 KDB_BACKEND(null, NULL, NULL, NULL);
76 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
78 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
79 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
80 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
81 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
82 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
83 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
85 static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
87 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
88 0, kdb_sysctl_available, "A", "list of available KDB backends");
90 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
91 0, kdb_sysctl_current, "A", "currently selected KDB backend");
93 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter,
94 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
95 kdb_sysctl_enter, "I", "set to enter the debugger");
97 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic,
98 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
99 kdb_sysctl_panic, "I", "set to panic the kernel");
101 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap,
102 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
103 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
105 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code,
106 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, 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,
110 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_TUN | CTLFLAG_SECURE,
111 &kdb_break_to_debugger, 0, "Enable break to debugger");
112 TUNABLE_INT("debug.kdb.break_to_debugger", &kdb_break_to_debugger);
114 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger,
115 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_TUN | CTLFLAG_SECURE,
116 &kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger");
117 TUNABLE_INT("debug.kdb.alt_break_to_debugger", &kdb_alt_break_to_debugger);
120 * Flag to indicate to debuggers why the debugger was entered.
122 const char * volatile kdb_why = KDB_WHY_UNSET;
125 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
127 struct kdb_dbbe **iter;
131 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
132 SET_FOREACH(iter, kdb_dbbe_set) {
133 if ((*iter)->dbbe_active == 0)
134 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
136 error = sbuf_finish(&sbuf);
142 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
147 if (kdb_dbbe != NULL)
148 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
151 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
152 if (error != 0 || req->newptr == NULL)
156 return (kdb_dbbe_select(buf));
160 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
164 error = sysctl_wire_old_buffer(req, sizeof(int));
167 error = sysctl_handle_int(oidp, &i, 0, req);
169 if (error != 0 || req->newptr == NULL)
173 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
178 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
182 error = sysctl_wire_old_buffer(req, sizeof(int));
185 error = sysctl_handle_int(oidp, &i, 0, req);
187 if (error != 0 || req->newptr == NULL)
189 panic("kdb_sysctl_panic");
194 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
197 int *addr = (int *)0x10;
199 error = sysctl_wire_old_buffer(req, sizeof(int));
202 error = sysctl_handle_int(oidp, &i, 0, req);
204 if (error != 0 || req->newptr == NULL)
210 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
213 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
215 error = sysctl_wire_old_buffer(req, sizeof(int));
218 error = sysctl_handle_int(oidp, &i, 0, req);
220 if (error != 0 || req->newptr == NULL)
222 (*fp)(0x11111111, 0x22222222, 0x33333333);
227 kdb_panic(const char *msg)
232 other_cpus = all_cpus;
233 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
234 stop_cpus_hard(other_cpus);
236 printf("KDB: panic\n");
244 printf("KDB: reboot requested\n");
249 * Solaris implements a new BREAK which is initiated by a character sequence
250 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
253 * Note that this function may be called from almost anywhere, with interrupts
254 * disabled and with unknown locks held, so it must not access data other than
255 * its arguments. Its up to the caller to ensure that the state variable is
259 #define KEY_CR 13 /* CR '\r' */
260 #define KEY_TILDE 126 /* ~ */
261 #define KEY_CRTLB 2 /* ^B */
262 #define KEY_CRTLP 16 /* ^P */
263 #define KEY_CRTLR 18 /* ^R */
265 /* States of th KDB "alternate break sequence" detecting state machine. */
267 KDB_ALT_BREAK_SEEN_NONE,
268 KDB_ALT_BREAK_SEEN_CR,
269 KDB_ALT_BREAK_SEEN_CR_TILDE,
276 if (!kdb_break_to_debugger)
278 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
279 return (KDB_REQ_DEBUGGER);
283 kdb_alt_break_state(int key, int *state)
287 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
289 *state = KDB_ALT_BREAK_SEEN_CR;
295 case KDB_ALT_BREAK_SEEN_CR:
296 *state = KDB_ALT_BREAK_SEEN_NONE;
297 if (key == KEY_TILDE)
298 *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
300 case KDB_ALT_BREAK_SEEN_CR_TILDE:
301 *state = KDB_ALT_BREAK_SEEN_NONE;
302 if (key == KEY_CRTLB)
303 brk = KDB_REQ_DEBUGGER;
304 else if (key == KEY_CRTLP)
306 else if (key == KEY_CRTLR)
307 brk = KDB_REQ_REBOOT;
309 case KDB_ALT_BREAK_SEEN_NONE:
311 *state = KDB_ALT_BREAK_SEEN_NONE;
318 kdb_alt_break_internal(int key, int *state, int force_gdb)
322 if (!kdb_alt_break_to_debugger)
324 brk = kdb_alt_break_state(key, state);
326 case KDB_REQ_DEBUGGER:
328 kdb_dbbe_select("gdb");
329 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
334 kdb_dbbe_select("gdb");
335 kdb_panic("Panic sequence on console");
346 kdb_alt_break(int key, int *state)
349 return (kdb_alt_break_internal(key, state, 0));
353 * This variation on kdb_alt_break() is used only by dcons, which has its own
354 * configuration flag to force GDB use regardless of the global KDB
358 kdb_alt_break_gdb(int key, int *state)
361 return (kdb_alt_break_internal(key, state, 1));
365 * Print a backtrace of the calling thread. The backtrace is generated by
366 * the selected debugger, provided it supports backtraces. If no debugger
367 * is selected or the current debugger does not support backtraces, this
368 * function silently returns.
375 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
376 printf("KDB: stack backtrace:\n");
377 kdb_dbbe->dbbe_trace();
383 printf("KDB: stack backtrace:\n");
385 stack_print_ddb(&st);
391 * Set/change the current backend.
395 kdb_dbbe_select(const char *name)
397 struct kdb_dbbe *be, **iter;
399 SET_FOREACH(iter, kdb_dbbe_set) {
401 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
410 * Enter the currently selected debugger. If a message has been provided,
411 * it is printed first. If the debugger does not support the enter method,
412 * it is entered by using breakpoint(), which enters the debugger through
413 * kdb_trap(). The 'why' argument will contain a more mechanically usable
414 * string than 'msg', and is relied upon by DDB scripting to identify the
415 * reason for entering the debugger so that the right script can be run.
418 kdb_enter(const char *why, const char *msg)
421 if (kdb_dbbe != NULL && kdb_active == 0) {
423 printf("KDB: enter: %s\n", msg);
426 kdb_why = KDB_WHY_UNSET;
431 * Initialize the kernel debugger interface.
437 struct kdb_dbbe *be, **iter;
443 SET_FOREACH(iter, kdb_dbbe_set) {
445 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
446 be->dbbe_active = (pri >= 0) ? 0 : -1;
452 if (kdb_dbbe != NULL) {
453 printf("KDB: debugger backends:");
454 SET_FOREACH(iter, kdb_dbbe_set) {
456 if (be->dbbe_active == 0)
457 printf(" %s", be->dbbe_name);
460 printf("KDB: current backend: %s\n",
461 kdb_dbbe->dbbe_name);
470 kdb_jmpbuf(jmp_buf new)
483 if (!kdb_active || kdb_jmpbufp == NULL)
486 longjmp(kdb_jmpbufp, 1);
491 * Thread related support functions.
495 kdb_thr_ctx(struct thread *thr)
497 #if defined(SMP) && defined(KDB_STOPPEDPCB)
501 if (thr == curthread)
504 #if defined(SMP) && defined(KDB_STOPPEDPCB)
505 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
506 if (pc->pc_curthread == thr &&
507 CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
508 return (KDB_STOPPEDPCB(pc));
511 return (thr->td_pcb);
520 p = LIST_FIRST(&allproc);
522 if (p->p_flag & P_INMEM) {
523 thr = FIRST_THREAD_IN_PROC(p);
527 p = LIST_NEXT(p, p_list);
533 kdb_thr_from_pid(pid_t pid)
537 p = LIST_FIRST(&allproc);
539 if (p->p_flag & P_INMEM && p->p_pid == pid)
540 return (FIRST_THREAD_IN_PROC(p));
541 p = LIST_NEXT(p, p_list);
547 kdb_thr_lookup(lwpid_t tid)
551 thr = kdb_thr_first();
552 while (thr != NULL && thr->td_tid != tid)
553 thr = kdb_thr_next(thr);
558 kdb_thr_next(struct thread *thr)
563 thr = TAILQ_NEXT(thr, td_plist);
567 p = LIST_NEXT(p, p_list);
568 if (p != NULL && (p->p_flag & P_INMEM))
569 thr = FIRST_THREAD_IN_PROC(p);
575 kdb_thr_select(struct thread *thr)
580 kdb_thrctx = kdb_thr_ctx(thr);
585 * Enter the debugger due to a trap.
589 kdb_trap(int type, int code, struct trapframe *tf)
599 if (be == NULL || be->dbbe_trap == NULL)
602 /* We reenter the debugger through kdb_reenter(). */
606 intr = intr_disable();
609 other_cpus = all_cpus;
610 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
611 stop_cpus_hard(other_cpus);
618 /* Let MD code do its thing first... */
619 kdb_cpu_trap(type, code);
621 makectx(tf, &kdb_pcb);
622 kdb_thr_select(curthread);
625 handled = be->dbbe_trap(type, code);
629 if (be == NULL || be->dbbe_trap == NULL)
631 printf("Switching to %s back-end\n", be->dbbe_name);
637 restart_cpus(stopped_cpus);