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);
81 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
82 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
83 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
84 static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
85 static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
86 static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
87 static int kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS);
89 static 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,
98 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
99 kdb_sysctl_enter, "I", "set to enter the debugger");
101 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic,
102 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
103 kdb_sysctl_panic, "I", "set to panic the kernel");
105 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap,
106 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
107 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
109 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code,
110 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
111 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
113 SYSCTL_PROC(_debug_kdb, OID_AUTO, stack_overflow,
114 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
115 kdb_sysctl_stack_overflow, "I", "set to cause a stack overflow");
117 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger,
118 CTLFLAG_RWTUN | CTLFLAG_SECURE,
119 &kdb_break_to_debugger, 0, "Enable break to debugger");
121 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger,
122 CTLFLAG_RWTUN | CTLFLAG_SECURE,
123 &kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger");
126 * Flag to indicate to debuggers why the debugger was entered.
128 const char * volatile kdb_why = KDB_WHY_UNSET;
131 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
133 struct kdb_dbbe **iter;
137 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
138 SET_FOREACH(iter, kdb_dbbe_set) {
139 if ((*iter)->dbbe_active == 0)
140 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
142 error = sbuf_finish(&sbuf);
148 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
153 if (kdb_dbbe != NULL)
154 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
157 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
158 if (error != 0 || req->newptr == NULL)
162 return (kdb_dbbe_select(buf));
166 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
170 error = sysctl_wire_old_buffer(req, sizeof(int));
173 error = sysctl_handle_int(oidp, &i, 0, req);
175 if (error != 0 || req->newptr == NULL)
179 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
184 kdb_sysctl_panic(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)
195 panic("kdb_sysctl_panic");
200 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
203 int *addr = (int *)0x10;
205 error = sysctl_wire_old_buffer(req, sizeof(int));
208 error = sysctl_handle_int(oidp, &i, 0, req);
210 if (error != 0 || req->newptr == NULL)
216 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
219 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
221 error = sysctl_wire_old_buffer(req, sizeof(int));
224 error = sysctl_handle_int(oidp, &i, 0, req);
226 if (error != 0 || req->newptr == NULL)
228 (*fp)(0x11111111, 0x22222222, 0x33333333);
232 static void kdb_stack_overflow(volatile int *x) __noinline;
234 kdb_stack_overflow(volatile int *x)
239 kdb_stack_overflow(x);
240 *x += PCPU_GET(cpuid) / 1000000;
244 kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS)
249 error = sysctl_wire_old_buffer(req, sizeof(int));
252 error = sysctl_handle_int(oidp, &i, 0, req);
254 if (error != 0 || req->newptr == NULL)
257 kdb_stack_overflow(&x);
262 kdb_panic(const char *msg)
265 printf("KDB: panic\n");
273 printf("KDB: reboot requested\n");
278 * Solaris implements a new BREAK which is initiated by a character sequence
279 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
282 * Note that this function may be called from almost anywhere, with interrupts
283 * disabled and with unknown locks held, so it must not access data other than
284 * its arguments. Its up to the caller to ensure that the state variable is
287 #define KEY_CR 13 /* CR '\r' */
288 #define KEY_TILDE 126 /* ~ */
289 #define KEY_CRTLB 2 /* ^B */
290 #define KEY_CRTLP 16 /* ^P */
291 #define KEY_CRTLR 18 /* ^R */
293 /* States of th KDB "alternate break sequence" detecting state machine. */
295 KDB_ALT_BREAK_SEEN_NONE,
296 KDB_ALT_BREAK_SEEN_CR,
297 KDB_ALT_BREAK_SEEN_CR_TILDE,
304 if (!kdb_break_to_debugger)
306 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
307 return (KDB_REQ_DEBUGGER);
311 kdb_alt_break_state(int key, int *state)
315 /* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
317 *state = KDB_ALT_BREAK_SEEN_CR;
323 case KDB_ALT_BREAK_SEEN_CR:
324 *state = KDB_ALT_BREAK_SEEN_NONE;
325 if (key == KEY_TILDE)
326 *state = KDB_ALT_BREAK_SEEN_CR_TILDE;
328 case KDB_ALT_BREAK_SEEN_CR_TILDE:
329 *state = KDB_ALT_BREAK_SEEN_NONE;
330 if (key == KEY_CRTLB)
331 brk = KDB_REQ_DEBUGGER;
332 else if (key == KEY_CRTLP)
334 else if (key == KEY_CRTLR)
335 brk = KDB_REQ_REBOOT;
337 case KDB_ALT_BREAK_SEEN_NONE:
339 *state = KDB_ALT_BREAK_SEEN_NONE;
346 kdb_alt_break_internal(int key, int *state, int force_gdb)
350 if (!kdb_alt_break_to_debugger)
352 brk = kdb_alt_break_state(key, state);
354 case KDB_REQ_DEBUGGER:
356 kdb_dbbe_select("gdb");
357 kdb_enter(KDB_WHY_BREAK, "Break to debugger");
362 kdb_dbbe_select("gdb");
363 kdb_panic("Panic sequence on console");
374 kdb_alt_break(int key, int *state)
377 return (kdb_alt_break_internal(key, state, 0));
381 * This variation on kdb_alt_break() is used only by dcons, which has its own
382 * configuration flag to force GDB use regardless of the global KDB
386 kdb_alt_break_gdb(int key, int *state)
389 return (kdb_alt_break_internal(key, state, 1));
393 * Print a backtrace of the calling thread. The backtrace is generated by
394 * the selected debugger, provided it supports backtraces. If no debugger
395 * is selected or the current debugger does not support backtraces, this
396 * function silently returns.
402 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
403 printf("KDB: stack backtrace:\n");
404 kdb_dbbe->dbbe_trace();
410 printf("KDB: stack backtrace:\n");
413 stack_print_ddb(&st);
419 * Similar to kdb_backtrace() except that it prints a backtrace of an
420 * arbitrary thread rather than the calling thread.
423 kdb_backtrace_thread(struct thread *td)
426 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
427 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
428 kdb_dbbe->dbbe_trace_thread(td);
434 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
436 stack_save_td(&st, td);
437 stack_print_ddb(&st);
443 * Set/change the current backend.
446 kdb_dbbe_select(const char *name)
448 struct kdb_dbbe *be, **iter;
450 SET_FOREACH(iter, kdb_dbbe_set) {
452 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
461 * Enter the currently selected debugger. If a message has been provided,
462 * it is printed first. If the debugger does not support the enter method,
463 * it is entered by using breakpoint(), which enters the debugger through
464 * kdb_trap(). The 'why' argument will contain a more mechanically usable
465 * string than 'msg', and is relied upon by DDB scripting to identify the
466 * reason for entering the debugger so that the right script can be run.
469 kdb_enter(const char *why, const char *msg)
472 if (kdb_dbbe != NULL && kdb_active == 0) {
474 printf("KDB: enter: %s\n", msg);
477 kdb_why = KDB_WHY_UNSET;
482 * Initialize the kernel debugger interface.
487 struct kdb_dbbe *be, **iter;
493 SET_FOREACH(iter, kdb_dbbe_set) {
495 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
496 be->dbbe_active = (pri >= 0) ? 0 : -1;
502 if (kdb_dbbe != NULL) {
503 printf("KDB: debugger backends:");
504 SET_FOREACH(iter, kdb_dbbe_set) {
506 if (be->dbbe_active == 0)
507 printf(" %s", be->dbbe_name);
510 printf("KDB: current backend: %s\n",
511 kdb_dbbe->dbbe_name);
519 kdb_jmpbuf(jmp_buf new)
532 if (!kdb_active || kdb_jmpbufp == NULL)
535 printf("KDB: reentering\n");
537 longjmp(kdb_jmpbufp, 1);
542 kdb_reenter_silent(void)
545 if (!kdb_active || kdb_jmpbufp == NULL)
548 longjmp(kdb_jmpbufp, 1);
553 * Thread-related support functions.
556 kdb_thr_ctx(struct thread *thr)
558 #if defined(SMP) && defined(KDB_STOPPEDPCB)
562 if (thr == curthread)
565 #if defined(SMP) && defined(KDB_STOPPEDPCB)
566 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
567 if (pc->pc_curthread == thr &&
568 CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
569 return (KDB_STOPPEDPCB(pc));
572 return (thr->td_pcb);
581 FOREACH_PROC_IN_SYSTEM(p) {
582 if (p->p_flag & P_INMEM) {
583 thr = FIRST_THREAD_IN_PROC(p);
592 kdb_thr_from_pid(pid_t pid)
596 FOREACH_PROC_IN_SYSTEM(p) {
597 if (p->p_flag & P_INMEM && p->p_pid == pid)
598 return (FIRST_THREAD_IN_PROC(p));
604 kdb_thr_lookup(lwpid_t tid)
608 thr = kdb_thr_first();
609 while (thr != NULL && thr->td_tid != tid)
610 thr = kdb_thr_next(thr);
615 kdb_thr_next(struct thread *thr)
620 thr = TAILQ_NEXT(thr, td_plist);
624 p = LIST_NEXT(p, p_list);
625 if (p != NULL && (p->p_flag & P_INMEM))
626 thr = FIRST_THREAD_IN_PROC(p);
632 kdb_thr_select(struct thread *thr)
637 kdb_thrctx = kdb_thr_ctx(thr);
642 * Enter the debugger due to a trap.
645 kdb_trap(int type, int code, struct trapframe *tf)
656 if (be == NULL || be->dbbe_trap == NULL)
659 /* We reenter the debugger through kdb_reenter(). */
663 intr = intr_disable();
665 if (!SCHEDULER_STOPPED()) {
667 other_cpus = all_cpus;
668 CPU_ANDNOT(&other_cpus, &stopped_cpus);
669 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
670 stop_cpus_hard(other_cpus);
672 curthread->td_stopsched = 1;
681 /* Let MD code do its thing first... */
682 kdb_cpu_trap(type, code);
684 makectx(tf, &kdb_pcb);
685 kdb_thr_select(curthread);
690 handled = be->dbbe_trap(type, code);
694 if (be == NULL || be->dbbe_trap == NULL)
696 printf("Switching to %s back-end\n", be->dbbe_name);
704 curthread->td_stopsched = 0;
706 CPU_AND(&other_cpus, &stopped_cpus);
707 restart_cpus(other_cpus);