2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2004 The FreeBSD Project
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
33 #include "opt_stack.h"
35 #include <sys/param.h>
36 #include <sys/systm.h>
39 #include <sys/kernel.h>
40 #include <sys/malloc.h>
46 #include <sys/stack.h>
47 #include <sys/sysctl.h>
49 #include <machine/kdb.h>
50 #include <machine/pcb.h>
53 #include <machine/smp.h>
56 u_char __read_frequently kdb_active = 0;
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, 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);
88 static int kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS);
90 static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
92 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
93 0, kdb_sysctl_available, "A", "list of available KDB backends");
95 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
96 0, kdb_sysctl_current, "A", "currently selected KDB backend");
98 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter,
99 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
100 kdb_sysctl_enter, "I", "set to enter the debugger");
102 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic,
103 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
104 kdb_sysctl_panic, "I", "set to panic the kernel");
106 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap,
107 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
108 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
110 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code,
111 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
112 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
114 SYSCTL_PROC(_debug_kdb, OID_AUTO, stack_overflow,
115 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
116 kdb_sysctl_stack_overflow, "I", "set to cause a stack overflow");
118 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger,
119 CTLFLAG_RWTUN | CTLFLAG_SECURE,
120 &kdb_break_to_debugger, 0, "Enable break to debugger");
122 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger,
123 CTLFLAG_RWTUN | CTLFLAG_SECURE,
124 &kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger");
127 * Flag to indicate to debuggers why the debugger was entered.
129 const char * volatile kdb_why = KDB_WHY_UNSET;
132 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
134 struct kdb_dbbe **iter;
138 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
139 SET_FOREACH(iter, kdb_dbbe_set) {
140 if ((*iter)->dbbe_active == 0)
141 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
143 error = sbuf_finish(&sbuf);
149 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
154 if (kdb_dbbe != NULL)
155 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
158 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
159 if (error != 0 || req->newptr == NULL)
163 return (kdb_dbbe_select(buf));
167 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
171 error = sysctl_wire_old_buffer(req, sizeof(int));
174 error = sysctl_handle_int(oidp, &i, 0, req);
176 if (error != 0 || req->newptr == NULL)
180 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
185 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
189 error = sysctl_wire_old_buffer(req, sizeof(int));
192 error = sysctl_handle_int(oidp, &i, 0, req);
194 if (error != 0 || req->newptr == NULL)
196 panic("kdb_sysctl_panic");
201 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
204 int *addr = (int *)0x10;
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)
217 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
220 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
222 error = sysctl_wire_old_buffer(req, sizeof(int));
225 error = sysctl_handle_int(oidp, &i, 0, req);
227 if (error != 0 || req->newptr == NULL)
229 (*fp)(0x11111111, 0x22222222, 0x33333333);
233 static void kdb_stack_overflow(volatile int *x) __noinline;
235 kdb_stack_overflow(volatile int *x)
240 kdb_stack_overflow(x);
241 *x += PCPU_GET(cpuid) / 1000000;
245 kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS)
250 error = sysctl_wire_old_buffer(req, sizeof(int));
253 error = sysctl_handle_int(oidp, &i, 0, req);
255 if (error != 0 || req->newptr == NULL)
258 kdb_stack_overflow(&x);
264 kdb_panic(const char *msg)
267 printf("KDB: panic\n");
275 printf("KDB: reboot requested\n");
280 * Solaris implements a new BREAK which is initiated by a character sequence
281 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
284 * Note that this function may be called from almost anywhere, with interrupts
285 * disabled and with unknown locks held, so it must not access data other than
286 * its arguments. Its up to the caller to ensure that the state variable is
289 #define KEY_CR 13 /* CR '\r' */
290 #define KEY_TILDE 126 /* ~ */
291 #define KEY_CRTLB 2 /* ^B */
292 #define KEY_CRTLP 16 /* ^P */
293 #define KEY_CRTLR 18 /* ^R */
295 /* States of th KDB "alternate break sequence" detecting state machine. */
297 KDB_ALT_BREAK_SEEN_NONE,
298 KDB_ALT_BREAK_SEEN_CR,
299 KDB_ALT_BREAK_SEEN_CR_TILDE,
306 if (!kdb_break_to_debugger)
308 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
309 return (KDB_REQ_DEBUGGER);
313 kdb_alt_break_state(int key, int *state)
317 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
319 *state = KDB_ALT_BREAK_SEEN_CR;
325 case KDB_ALT_BREAK_SEEN_CR:
326 *state = KDB_ALT_BREAK_SEEN_NONE;
327 if (key == KEY_TILDE)
328 *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
330 case KDB_ALT_BREAK_SEEN_CR_TILDE:
331 *state = KDB_ALT_BREAK_SEEN_NONE;
332 if (key == KEY_CRTLB)
333 brk = KDB_REQ_DEBUGGER;
334 else if (key == KEY_CRTLP)
336 else if (key == KEY_CRTLR)
337 brk = KDB_REQ_REBOOT;
339 case KDB_ALT_BREAK_SEEN_NONE:
341 *state = KDB_ALT_BREAK_SEEN_NONE;
348 kdb_alt_break_internal(int key, int *state, int force_gdb)
352 if (!kdb_alt_break_to_debugger)
354 brk = kdb_alt_break_state(key, state);
356 case KDB_REQ_DEBUGGER:
358 kdb_dbbe_select("gdb");
359 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
364 kdb_dbbe_select("gdb");
365 kdb_panic("Panic sequence on console");
376 kdb_alt_break(int key, int *state)
379 return (kdb_alt_break_internal(key, state, 0));
383 * This variation on kdb_alt_break() is used only by dcons, which has its own
384 * configuration flag to force GDB use regardless of the global KDB
388 kdb_alt_break_gdb(int key, int *state)
391 return (kdb_alt_break_internal(key, state, 1));
395 * Print a backtrace of the calling thread. The backtrace is generated by
396 * the selected debugger, provided it supports backtraces. If no debugger
397 * is selected or the current debugger does not support backtraces, this
398 * function silently returns.
404 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
405 printf("KDB: stack backtrace:\n");
406 kdb_dbbe->dbbe_trace();
412 printf("KDB: stack backtrace:\n");
415 stack_print_ddb(&st);
421 * Similar to kdb_backtrace() except that it prints a backtrace of an
422 * arbitrary thread rather than the calling thread.
425 kdb_backtrace_thread(struct thread *td)
428 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
429 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
430 kdb_dbbe->dbbe_trace_thread(td);
436 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
438 stack_save_td(&st, td);
439 stack_print_ddb(&st);
445 * Set/change the current backend.
448 kdb_dbbe_select(const char *name)
450 struct kdb_dbbe *be, **iter;
452 SET_FOREACH(iter, kdb_dbbe_set) {
454 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
463 * Enter the currently selected debugger. If a message has been provided,
464 * it is printed first. If the debugger does not support the enter method,
465 * it is entered by using breakpoint(), which enters the debugger through
466 * kdb_trap(). The 'why' argument will contain a more mechanically usable
467 * string than 'msg', and is relied upon by DDB scripting to identify the
468 * reason for entering the debugger so that the right script can be run.
471 kdb_enter(const char *why, const char *msg)
474 if (kdb_dbbe != NULL && kdb_active == 0) {
476 printf("KDB: enter: %s\n", msg);
479 kdb_why = KDB_WHY_UNSET;
484 * Initialize the kernel debugger interface.
489 struct kdb_dbbe *be, **iter;
495 SET_FOREACH(iter, kdb_dbbe_set) {
497 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
498 be->dbbe_active = (pri >= 0) ? 0 : -1;
504 if (kdb_dbbe != NULL) {
505 printf("KDB: debugger backends:");
506 SET_FOREACH(iter, kdb_dbbe_set) {
508 if (be->dbbe_active == 0)
509 printf(" %s", be->dbbe_name);
512 printf("KDB: current backend: %s\n",
513 kdb_dbbe->dbbe_name);
521 kdb_jmpbuf(jmp_buf new)
534 if (!kdb_active || kdb_jmpbufp == NULL)
537 printf("KDB: reentering\n");
539 longjmp(kdb_jmpbufp, 1);
544 kdb_reenter_silent(void)
547 if (!kdb_active || kdb_jmpbufp == NULL)
550 longjmp(kdb_jmpbufp, 1);
555 * Thread-related support functions.
558 kdb_thr_ctx(struct thread *thr)
560 #if defined(SMP) && defined(KDB_STOPPEDPCB)
564 if (thr == curthread)
567 #if defined(SMP) && defined(KDB_STOPPEDPCB)
568 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
569 if (pc->pc_curthread == thr &&
570 CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
571 return (KDB_STOPPEDPCB(pc));
574 return (thr->td_pcb);
583 FOREACH_PROC_IN_SYSTEM(p) {
584 if (p->p_flag & P_INMEM) {
585 thr = FIRST_THREAD_IN_PROC(p);
594 kdb_thr_from_pid(pid_t pid)
598 FOREACH_PROC_IN_SYSTEM(p) {
599 if (p->p_flag & P_INMEM && p->p_pid == pid)
600 return (FIRST_THREAD_IN_PROC(p));
606 kdb_thr_lookup(lwpid_t tid)
610 thr = kdb_thr_first();
611 while (thr != NULL && thr->td_tid != tid)
612 thr = kdb_thr_next(thr);
617 kdb_thr_next(struct thread *thr)
622 thr = TAILQ_NEXT(thr, td_plist);
626 p = LIST_NEXT(p, p_list);
627 if (p != NULL && (p->p_flag & P_INMEM))
628 thr = FIRST_THREAD_IN_PROC(p);
634 kdb_thr_select(struct thread *thr)
639 kdb_thrctx = kdb_thr_ctx(thr);
644 * Enter the debugger due to a trap.
647 kdb_trap(int type, int code, struct trapframe *tf)
658 if (be == NULL || be->dbbe_trap == NULL)
661 /* We reenter the debugger through kdb_reenter(). */
665 intr = intr_disable();
667 if (!SCHEDULER_STOPPED()) {
669 other_cpus = all_cpus;
670 CPU_NAND(&other_cpus, &stopped_cpus);
671 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
672 stop_cpus_hard(other_cpus);
674 curthread->td_stopsched = 1;
683 /* Let MD code do its thing first... */
684 kdb_cpu_trap(type, code);
686 makectx(tf, &kdb_pcb);
687 kdb_thr_select(curthread);
692 handled = be->dbbe_trap(type, code);
696 if (be == NULL || be->dbbe_trap == NULL)
698 printf("Switching to %s back-end\n", be->dbbe_name);
706 curthread->td_stopsched = 0;
708 CPU_AND(&other_cpus, &stopped_cpus);
709 restart_cpus(other_cpus);