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>
53 u_char __read_frequently kdb_active = 0;
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);
85 static int kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS);
87 static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
89 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
90 0, kdb_sysctl_available, "A", "list of available KDB backends");
92 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
93 0, kdb_sysctl_current, "A", "currently selected KDB backend");
95 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter,
96 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
97 kdb_sysctl_enter, "I", "set to enter the debugger");
99 SYSCTL_PROC(_debug_kdb, OID_AUTO, panic,
100 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
101 kdb_sysctl_panic, "I", "set to panic the kernel");
103 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap,
104 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
105 kdb_sysctl_trap, "I", "set to cause a page fault via data access");
107 SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code,
108 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
109 kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
111 SYSCTL_PROC(_debug_kdb, OID_AUTO, stack_overflow,
112 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
113 kdb_sysctl_stack_overflow, "I", "set to cause a stack overflow");
115 SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger,
116 CTLFLAG_RWTUN | CTLFLAG_SECURE,
117 &kdb_break_to_debugger, 0, "Enable break to debugger");
119 SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger,
120 CTLFLAG_RWTUN | CTLFLAG_SECURE,
121 &kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger");
124 * Flag to indicate to debuggers why the debugger was entered.
126 const char * volatile kdb_why = KDB_WHY_UNSET;
129 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
131 struct kdb_dbbe **iter;
135 sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
136 SET_FOREACH(iter, kdb_dbbe_set) {
137 if ((*iter)->dbbe_active == 0)
138 sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
140 error = sbuf_finish(&sbuf);
146 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
151 if (kdb_dbbe != NULL)
152 strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
155 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
156 if (error != 0 || req->newptr == NULL)
160 return (kdb_dbbe_select(buf));
164 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
168 error = sysctl_wire_old_buffer(req, sizeof(int));
171 error = sysctl_handle_int(oidp, &i, 0, req);
173 if (error != 0 || req->newptr == NULL)
177 kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
182 kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
186 error = sysctl_wire_old_buffer(req, sizeof(int));
189 error = sysctl_handle_int(oidp, &i, 0, req);
191 if (error != 0 || req->newptr == NULL)
193 panic("kdb_sysctl_panic");
198 kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
201 int *addr = (int *)0x10;
203 error = sysctl_wire_old_buffer(req, sizeof(int));
206 error = sysctl_handle_int(oidp, &i, 0, req);
208 if (error != 0 || req->newptr == NULL)
214 kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
217 void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
219 error = sysctl_wire_old_buffer(req, sizeof(int));
222 error = sysctl_handle_int(oidp, &i, 0, req);
224 if (error != 0 || req->newptr == NULL)
226 (*fp)(0x11111111, 0x22222222, 0x33333333);
230 static void kdb_stack_overflow(volatile int *x) __noinline;
232 kdb_stack_overflow(volatile int *x)
237 kdb_stack_overflow(x);
238 *x += PCPU_GET(cpuid) / 1000000;
242 kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS)
247 error = sysctl_wire_old_buffer(req, sizeof(int));
250 error = sysctl_handle_int(oidp, &i, 0, req);
252 if (error != 0 || req->newptr == NULL)
255 kdb_stack_overflow(&x);
261 kdb_panic(const char *msg)
264 printf("KDB: panic\n");
272 printf("KDB: reboot requested\n");
277 * Solaris implements a new BREAK which is initiated by a character sequence
278 * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
281 * Note that this function may be called from almost anywhere, with interrupts
282 * disabled and with unknown locks held, so it must not access data other than
283 * 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.
403 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
404 printf("KDB: stack backtrace:\n");
405 kdb_dbbe->dbbe_trace();
411 printf("KDB: stack backtrace:\n");
414 stack_print_ddb(&st);
420 * Similar to kdb_backtrace() except that it prints a backtrace of an
421 * arbitrary thread rather than the calling thread.
424 kdb_backtrace_thread(struct thread *td)
427 if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
428 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
429 kdb_dbbe->dbbe_trace_thread(td);
435 printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
437 stack_save_td(&st, td);
438 stack_print_ddb(&st);
444 * 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.
490 struct kdb_dbbe *be, **iter;
496 SET_FOREACH(iter, kdb_dbbe_set) {
498 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
499 be->dbbe_active = (pri >= 0) ? 0 : -1;
505 if (kdb_dbbe != NULL) {
506 printf("KDB: debugger backends:");
507 SET_FOREACH(iter, kdb_dbbe_set) {
509 if (be->dbbe_active == 0)
510 printf(" %s", be->dbbe_name);
513 printf("KDB: current backend: %s\n",
514 kdb_dbbe->dbbe_name);
523 kdb_jmpbuf(jmp_buf new)
536 if (!kdb_active || kdb_jmpbufp == NULL)
539 printf("KDB: reentering\n");
541 longjmp(kdb_jmpbufp, 1);
546 * Thread related support functions.
550 kdb_thr_ctx(struct thread *thr)
552 #if defined(SMP) && defined(KDB_STOPPEDPCB)
556 if (thr == curthread)
559 #if defined(SMP) && defined(KDB_STOPPEDPCB)
560 STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
561 if (pc->pc_curthread == thr &&
562 CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
563 return (KDB_STOPPEDPCB(pc));
566 return (thr->td_pcb);
575 p = LIST_FIRST(&allproc);
577 if (p->p_flag & P_INMEM) {
578 thr = FIRST_THREAD_IN_PROC(p);
582 p = LIST_NEXT(p, p_list);
588 kdb_thr_from_pid(pid_t pid)
592 p = LIST_FIRST(&allproc);
594 if (p->p_flag & P_INMEM && p->p_pid == pid)
595 return (FIRST_THREAD_IN_PROC(p));
596 p = LIST_NEXT(p, p_list);
602 kdb_thr_lookup(lwpid_t tid)
606 thr = kdb_thr_first();
607 while (thr != NULL && thr->td_tid != tid)
608 thr = kdb_thr_next(thr);
613 kdb_thr_next(struct thread *thr)
618 thr = TAILQ_NEXT(thr, td_plist);
622 p = LIST_NEXT(p, p_list);
623 if (p != NULL && (p->p_flag & P_INMEM))
624 thr = FIRST_THREAD_IN_PROC(p);
630 kdb_thr_select(struct thread *thr)
635 kdb_thrctx = kdb_thr_ctx(thr);
640 * Enter the debugger due to a trap.
644 kdb_trap(int type, int code, struct trapframe *tf)
657 if (be == NULL || be->dbbe_trap == NULL)
660 /* We reenter the debugger through kdb_reenter(). */
664 intr = intr_disable();
667 if (!SCHEDULER_STOPPED()) {
668 other_cpus = all_cpus;
669 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
670 stop_cpus_hard(other_cpus);
680 /* Let MD code do its thing first... */
681 kdb_cpu_trap(type, code);
683 makectx(tf, &kdb_pcb);
684 kdb_thr_select(curthread);
689 handled = be->dbbe_trap(type, code);
693 if (be == NULL || be->dbbe_trap == NULL)
695 printf("Switching to %s back-end\n", be->dbbe_name);
704 restart_cpus(stopped_cpus);