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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Kernel Debug Core
4 *
5 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
6 *
7 * Copyright (C) 2000-2001 VERITAS Software Corporation.
8 * Copyright (C) 2002-2004 Timesys Corporation
9 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
10 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
11 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
12 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
13 * Copyright (C) 2005-2009 Wind River Systems, Inc.
14 * Copyright (C) 2007 MontaVista Software, Inc.
15 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
16 *
17 * Contributors at various stages not listed above:
18 * Jason Wessel ( jason.wessel@windriver.com )
19 * George Anzinger <george@mvista.com>
20 * Anurekh Saxena (anurekh.saxena@timesys.com)
21 * Lake Stevens Instrument Division (Glenn Engel)
22 * Jim Kingdon, Cygnus Support.
23 *
24 * Original KGDB stub: David Grothe <dave@gcom.com>,
25 * Tigran Aivazian <tigran@sco.com>
26 */
27
28#define pr_fmt(fmt) "KGDB: " fmt
29
30#include <linux/pid_namespace.h>
31#include <linux/clocksource.h>
32#include <linux/serial_core.h>
33#include <linux/interrupt.h>
34#include <linux/spinlock.h>
35#include <linux/console.h>
36#include <linux/threads.h>
37#include <linux/uaccess.h>
38#include <linux/kernel.h>
39#include <linux/module.h>
40#include <linux/ptrace.h>
41#include <linux/string.h>
42#include <linux/delay.h>
43#include <linux/sched.h>
44#include <linux/sysrq.h>
45#include <linux/reboot.h>
46#include <linux/init.h>
47#include <linux/kgdb.h>
48#include <linux/kdb.h>
49#include <linux/nmi.h>
50#include <linux/pid.h>
51#include <linux/smp.h>
52#include <linux/mm.h>
53#include <linux/rcupdate.h>
54#include <linux/irq.h>
55#include <linux/security.h>
56
57#include <asm/cacheflush.h>
58#include <asm/byteorder.h>
59#include <linux/atomic.h>
60
61#include "debug_core.h"
62
63static int kgdb_break_asap;
64
65struct debuggerinfo_struct kgdb_info[NR_CPUS];
66
67/* kgdb_connected - Is a host GDB connected to us? */
68int kgdb_connected;
69EXPORT_SYMBOL_GPL(kgdb_connected);
70
71/* All the KGDB handlers are installed */
72int kgdb_io_module_registered;
73
74/* Guard for recursive entry */
75static int exception_level;
76
77struct kgdb_io *dbg_io_ops;
78static DEFINE_SPINLOCK(kgdb_registration_lock);
79
80/* Action for the reboot notifier, a global allow kdb to change it */
81static int kgdbreboot;
82/* kgdb console driver is loaded */
83static int kgdb_con_registered;
84/* determine if kgdb console output should be used */
85static int kgdb_use_con;
86/* Flag for alternate operations for early debugging */
87bool dbg_is_early = true;
88/* Next cpu to become the master debug core */
89int dbg_switch_cpu;
90
91/* Use kdb or gdbserver mode */
92int dbg_kdb_mode = 1;
93
94module_param(kgdb_use_con, int, 0644);
95module_param(kgdbreboot, int, 0644);
96
97/*
98 * Holds information about breakpoints in a kernel. These breakpoints are
99 * added and removed by gdb.
100 */
101static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
102 [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
103};
104
105/*
106 * The CPU# of the active CPU, or -1 if none:
107 */
108atomic_t kgdb_active = ATOMIC_INIT(-1);
109EXPORT_SYMBOL_GPL(kgdb_active);
110static DEFINE_RAW_SPINLOCK(dbg_master_lock);
111static DEFINE_RAW_SPINLOCK(dbg_slave_lock);
112
113/*
114 * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
115 * bootup code (which might not have percpu set up yet):
116 */
117static atomic_t masters_in_kgdb;
118static atomic_t slaves_in_kgdb;
119atomic_t kgdb_setting_breakpoint;
120
121struct task_struct *kgdb_usethread;
122struct task_struct *kgdb_contthread;
123
124int kgdb_single_step;
125static pid_t kgdb_sstep_pid;
126
127/* to keep track of the CPU which is doing the single stepping*/
128atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
129
130/*
131 * If you are debugging a problem where roundup (the collection of
132 * all other CPUs) is a problem [this should be extremely rare],
133 * then use the nokgdbroundup option to avoid roundup. In that case
134 * the other CPUs might interfere with your debugging context, so
135 * use this with care:
136 */
137static int kgdb_do_roundup = 1;
138
139static int __init opt_nokgdbroundup(char *str)
140{
141 kgdb_do_roundup = 0;
142
143 return 0;
144}
145
146early_param("nokgdbroundup", opt_nokgdbroundup);
147
148/*
149 * Finally, some KGDB code :-)
150 */
151
152/*
153 * Weak aliases for breakpoint management,
154 * can be overridden by architectures when needed:
155 */
156int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
157{
158 int err;
159
160 err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr,
161 BREAK_INSTR_SIZE);
162 if (err)
163 return err;
164 err = copy_to_kernel_nofault((char *)bpt->bpt_addr,
165 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
166 return err;
167}
168NOKPROBE_SYMBOL(kgdb_arch_set_breakpoint);
169
170int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
171{
172 return copy_to_kernel_nofault((char *)bpt->bpt_addr,
173 (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
174}
175NOKPROBE_SYMBOL(kgdb_arch_remove_breakpoint);
176
177int __weak kgdb_validate_break_address(unsigned long addr)
178{
179 struct kgdb_bkpt tmp;
180 int err;
181
182 if (kgdb_within_blocklist(addr))
183 return -EINVAL;
184
185 /* Validate setting the breakpoint and then removing it. If the
186 * remove fails, the kernel needs to emit a bad message because we
187 * are deep trouble not being able to put things back the way we
188 * found them.
189 */
190 tmp.bpt_addr = addr;
191 err = kgdb_arch_set_breakpoint(&tmp);
192 if (err)
193 return err;
194 err = kgdb_arch_remove_breakpoint(&tmp);
195 if (err)
196 pr_err("Critical breakpoint error, kernel memory destroyed at: %lx\n",
197 addr);
198 return err;
199}
200
201unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
202{
203 return instruction_pointer(regs);
204}
205NOKPROBE_SYMBOL(kgdb_arch_pc);
206
207int __weak kgdb_arch_init(void)
208{
209 return 0;
210}
211
212int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
213{
214 return 0;
215}
216NOKPROBE_SYMBOL(kgdb_skipexception);
217
218#ifdef CONFIG_SMP
219
220/*
221 * Default (weak) implementation for kgdb_roundup_cpus
222 */
223
224void __weak kgdb_call_nmi_hook(void *ignored)
225{
226 /*
227 * NOTE: get_irq_regs() is supposed to get the registers from
228 * before the IPI interrupt happened and so is supposed to
229 * show where the processor was. In some situations it's
230 * possible we might be called without an IPI, so it might be
231 * safer to figure out how to make kgdb_breakpoint() work
232 * properly here.
233 */
234 kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
235}
236NOKPROBE_SYMBOL(kgdb_call_nmi_hook);
237
238static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd) =
239 CSD_INIT(kgdb_call_nmi_hook, NULL);
240
241void __weak kgdb_roundup_cpus(void)
242{
243 call_single_data_t *csd;
244 int this_cpu = raw_smp_processor_id();
245 int cpu;
246 int ret;
247
248 for_each_online_cpu(cpu) {
249 /* No need to roundup ourselves */
250 if (cpu == this_cpu)
251 continue;
252
253 csd = &per_cpu(kgdb_roundup_csd, cpu);
254
255 /*
256 * If it didn't round up last time, don't try again
257 * since smp_call_function_single_async() will block.
258 *
259 * If rounding_up is false then we know that the
260 * previous call must have at least started and that
261 * means smp_call_function_single_async() won't block.
262 */
263 if (kgdb_info[cpu].rounding_up)
264 continue;
265 kgdb_info[cpu].rounding_up = true;
266
267 ret = smp_call_function_single_async(cpu, csd);
268 if (ret)
269 kgdb_info[cpu].rounding_up = false;
270 }
271}
272NOKPROBE_SYMBOL(kgdb_roundup_cpus);
273
274#endif
275
276/*
277 * Some architectures need cache flushes when we set/clear a
278 * breakpoint:
279 */
280static void kgdb_flush_swbreak_addr(unsigned long addr)
281{
282 if (!CACHE_FLUSH_IS_SAFE)
283 return;
284
285 /* Force flush instruction cache if it was outside the mm */
286 flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
287}
288NOKPROBE_SYMBOL(kgdb_flush_swbreak_addr);
289
290/*
291 * SW breakpoint management:
292 */
293int dbg_activate_sw_breakpoints(void)
294{
295 int error;
296 int ret = 0;
297 int i;
298
299 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
300 if (kgdb_break[i].state != BP_SET)
301 continue;
302
303 error = kgdb_arch_set_breakpoint(&kgdb_break[i]);
304 if (error) {
305 ret = error;
306 pr_info("BP install failed: %lx\n",
307 kgdb_break[i].bpt_addr);
308 continue;
309 }
310
311 kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr);
312 kgdb_break[i].state = BP_ACTIVE;
313 }
314 return ret;
315}
316NOKPROBE_SYMBOL(dbg_activate_sw_breakpoints);
317
318int dbg_set_sw_break(unsigned long addr)
319{
320 int err = kgdb_validate_break_address(addr);
321 int breakno = -1;
322 int i;
323
324 if (err)
325 return err;
326
327 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
328 if ((kgdb_break[i].state == BP_SET) &&
329 (kgdb_break[i].bpt_addr == addr))
330 return -EEXIST;
331 }
332 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
333 if (kgdb_break[i].state == BP_REMOVED &&
334 kgdb_break[i].bpt_addr == addr) {
335 breakno = i;
336 break;
337 }
338 }
339
340 if (breakno == -1) {
341 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
342 if (kgdb_break[i].state == BP_UNDEFINED) {
343 breakno = i;
344 break;
345 }
346 }
347 }
348
349 if (breakno == -1)
350 return -E2BIG;
351
352 kgdb_break[breakno].state = BP_SET;
353 kgdb_break[breakno].type = BP_BREAKPOINT;
354 kgdb_break[breakno].bpt_addr = addr;
355
356 return 0;
357}
358
359int dbg_deactivate_sw_breakpoints(void)
360{
361 int error;
362 int ret = 0;
363 int i;
364
365 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
366 if (kgdb_break[i].state != BP_ACTIVE)
367 continue;
368 error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
369 if (error) {
370 pr_info("BP remove failed: %lx\n",
371 kgdb_break[i].bpt_addr);
372 ret = error;
373 }
374
375 kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr);
376 kgdb_break[i].state = BP_SET;
377 }
378 return ret;
379}
380NOKPROBE_SYMBOL(dbg_deactivate_sw_breakpoints);
381
382int dbg_remove_sw_break(unsigned long addr)
383{
384 int i;
385
386 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
387 if ((kgdb_break[i].state == BP_SET) &&
388 (kgdb_break[i].bpt_addr == addr)) {
389 kgdb_break[i].state = BP_REMOVED;
390 return 0;
391 }
392 }
393 return -ENOENT;
394}
395
396int kgdb_isremovedbreak(unsigned long addr)
397{
398 int i;
399
400 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
401 if ((kgdb_break[i].state == BP_REMOVED) &&
402 (kgdb_break[i].bpt_addr == addr))
403 return 1;
404 }
405 return 0;
406}
407
408int kgdb_has_hit_break(unsigned long addr)
409{
410 int i;
411
412 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
413 if (kgdb_break[i].state == BP_ACTIVE &&
414 kgdb_break[i].bpt_addr == addr)
415 return 1;
416 }
417 return 0;
418}
419
420int dbg_remove_all_break(void)
421{
422 int error;
423 int i;
424
425 /* Clear memory breakpoints. */
426 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
427 if (kgdb_break[i].state != BP_ACTIVE)
428 goto setundefined;
429 error = kgdb_arch_remove_breakpoint(&kgdb_break[i]);
430 if (error)
431 pr_err("breakpoint remove failed: %lx\n",
432 kgdb_break[i].bpt_addr);
433setundefined:
434 kgdb_break[i].state = BP_UNDEFINED;
435 }
436
437 /* Clear hardware breakpoints. */
438 if (arch_kgdb_ops.remove_all_hw_break)
439 arch_kgdb_ops.remove_all_hw_break();
440
441 return 0;
442}
443
444void kgdb_free_init_mem(void)
445{
446 int i;
447
448 /* Clear init memory breakpoints. */
449 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
450 if (init_section_contains((void *)kgdb_break[i].bpt_addr, 0))
451 kgdb_break[i].state = BP_UNDEFINED;
452 }
453}
454
455#ifdef CONFIG_KGDB_KDB
456void kdb_dump_stack_on_cpu(int cpu)
457{
458 if (cpu == raw_smp_processor_id() || !IS_ENABLED(CONFIG_SMP)) {
459 dump_stack();
460 return;
461 }
462
463 if (!(kgdb_info[cpu].exception_state & DCPU_IS_SLAVE)) {
464 kdb_printf("ERROR: Task on cpu %d didn't stop in the debugger\n",
465 cpu);
466 return;
467 }
468
469 /*
470 * In general, architectures don't support dumping the stack of a
471 * "running" process that's not the current one. From the point of
472 * view of the Linux, kernel processes that are looping in the kgdb
473 * slave loop are still "running". There's also no API (that actually
474 * works across all architectures) that can do a stack crawl based
475 * on registers passed as a parameter.
476 *
477 * Solve this conundrum by asking slave CPUs to do the backtrace
478 * themselves.
479 */
480 kgdb_info[cpu].exception_state |= DCPU_WANT_BT;
481 while (kgdb_info[cpu].exception_state & DCPU_WANT_BT)
482 cpu_relax();
483}
484#endif
485
486/*
487 * Return true if there is a valid kgdb I/O module. Also if no
488 * debugger is attached a message can be printed to the console about
489 * waiting for the debugger to attach.
490 *
491 * The print_wait argument is only to be true when called from inside
492 * the core kgdb_handle_exception, because it will wait for the
493 * debugger to attach.
494 */
495static int kgdb_io_ready(int print_wait)
496{
497 if (!dbg_io_ops)
498 return 0;
499 if (kgdb_connected)
500 return 1;
501 if (atomic_read(&kgdb_setting_breakpoint))
502 return 1;
503 if (print_wait) {
504#ifdef CONFIG_KGDB_KDB
505 if (!dbg_kdb_mode)
506 pr_crit("waiting... or $3#33 for KDB\n");
507#else
508 pr_crit("Waiting for remote debugger\n");
509#endif
510 }
511 return 1;
512}
513NOKPROBE_SYMBOL(kgdb_io_ready);
514
515static int kgdb_reenter_check(struct kgdb_state *ks)
516{
517 unsigned long addr;
518
519 if (atomic_read(&kgdb_active) != raw_smp_processor_id())
520 return 0;
521
522 /* Panic on recursive debugger calls: */
523 exception_level++;
524 addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
525 dbg_deactivate_sw_breakpoints();
526
527 /*
528 * If the break point removed ok at the place exception
529 * occurred, try to recover and print a warning to the end
530 * user because the user planted a breakpoint in a place that
531 * KGDB needs in order to function.
532 */
533 if (dbg_remove_sw_break(addr) == 0) {
534 exception_level = 0;
535 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
536 dbg_activate_sw_breakpoints();
537 pr_crit("re-enter error: breakpoint removed %lx\n", addr);
538 WARN_ON_ONCE(1);
539
540 return 1;
541 }
542 dbg_remove_all_break();
543 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
544
545 if (exception_level > 1) {
546 dump_stack();
547 kgdb_io_module_registered = false;
548 panic("Recursive entry to debugger");
549 }
550
551 pr_crit("re-enter exception: ALL breakpoints killed\n");
552#ifdef CONFIG_KGDB_KDB
553 /* Allow kdb to debug itself one level */
554 return 0;
555#endif
556 dump_stack();
557 panic("Recursive entry to debugger");
558
559 return 1;
560}
561NOKPROBE_SYMBOL(kgdb_reenter_check);
562
563static void dbg_touch_watchdogs(void)
564{
565 touch_softlockup_watchdog_sync();
566 clocksource_touch_watchdog();
567 rcu_cpu_stall_reset();
568}
569NOKPROBE_SYMBOL(dbg_touch_watchdogs);
570
571static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
572 int exception_state)
573{
574 unsigned long flags;
575 int sstep_tries = 100;
576 int error;
577 int cpu;
578 int trace_on = 0;
579 int online_cpus = num_online_cpus();
580 u64 time_left;
581
582 kgdb_info[ks->cpu].enter_kgdb++;
583 kgdb_info[ks->cpu].exception_state |= exception_state;
584
585 if (exception_state == DCPU_WANT_MASTER)
586 atomic_inc(&masters_in_kgdb);
587 else
588 atomic_inc(&slaves_in_kgdb);
589
590 if (arch_kgdb_ops.disable_hw_break)
591 arch_kgdb_ops.disable_hw_break(regs);
592
593acquirelock:
594 rcu_read_lock();
595 /*
596 * Interrupts will be restored by the 'trap return' code, except when
597 * single stepping.
598 */
599 local_irq_save(flags);
600
601 cpu = ks->cpu;
602 kgdb_info[cpu].debuggerinfo = regs;
603 kgdb_info[cpu].task = current;
604 kgdb_info[cpu].ret_state = 0;
605 kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT;
606
607 /* Make sure the above info reaches the primary CPU */
608 smp_mb();
609
610 if (exception_level == 1) {
611 if (raw_spin_trylock(&dbg_master_lock))
612 atomic_xchg(&kgdb_active, cpu);
613 goto cpu_master_loop;
614 }
615
616 /*
617 * CPU will loop if it is a slave or request to become a kgdb
618 * master cpu and acquire the kgdb_active lock:
619 */
620 while (1) {
621cpu_loop:
622 if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) {
623 kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER;
624 goto cpu_master_loop;
625 } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
626 if (raw_spin_trylock(&dbg_master_lock)) {
627 atomic_xchg(&kgdb_active, cpu);
628 break;
629 }
630 } else if (kgdb_info[cpu].exception_state & DCPU_WANT_BT) {
631 dump_stack();
632 kgdb_info[cpu].exception_state &= ~DCPU_WANT_BT;
633 } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
634 if (!raw_spin_is_locked(&dbg_slave_lock))
635 goto return_normal;
636 } else {
637return_normal:
638 /* Return to normal operation by executing any
639 * hw breakpoint fixup.
640 */
641 if (arch_kgdb_ops.correct_hw_break)
642 arch_kgdb_ops.correct_hw_break();
643 if (trace_on)
644 tracing_on();
645 kgdb_info[cpu].debuggerinfo = NULL;
646 kgdb_info[cpu].task = NULL;
647 kgdb_info[cpu].exception_state &=
648 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
649 kgdb_info[cpu].enter_kgdb--;
650 smp_mb__before_atomic();
651 atomic_dec(&slaves_in_kgdb);
652 dbg_touch_watchdogs();
653 local_irq_restore(flags);
654 rcu_read_unlock();
655 return 0;
656 }
657 cpu_relax();
658 }
659
660 /*
661 * For single stepping, try to only enter on the processor
662 * that was single stepping. To guard against a deadlock, the
663 * kernel will only try for the value of sstep_tries before
664 * giving up and continuing on.
665 */
666 if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
667 (kgdb_info[cpu].task &&
668 kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
669 atomic_set(&kgdb_active, -1);
670 raw_spin_unlock(&dbg_master_lock);
671 dbg_touch_watchdogs();
672 local_irq_restore(flags);
673 rcu_read_unlock();
674
675 goto acquirelock;
676 }
677
678 if (!kgdb_io_ready(1)) {
679 kgdb_info[cpu].ret_state = 1;
680 goto kgdb_restore; /* No I/O connection, resume the system */
681 }
682
683 /*
684 * Don't enter if we have hit a removed breakpoint.
685 */
686 if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
687 goto kgdb_restore;
688
689 atomic_inc(&ignore_console_lock_warning);
690
691 /* Call the I/O driver's pre_exception routine */
692 if (dbg_io_ops->pre_exception)
693 dbg_io_ops->pre_exception();
694
695 /*
696 * Get the passive CPU lock which will hold all the non-primary
697 * CPU in a spin state while the debugger is active
698 */
699 if (!kgdb_single_step)
700 raw_spin_lock(&dbg_slave_lock);
701
702#ifdef CONFIG_SMP
703 /* If send_ready set, slaves are already waiting */
704 if (ks->send_ready)
705 atomic_set(ks->send_ready, 1);
706
707 /* Signal the other CPUs to enter kgdb_wait() */
708 else if ((!kgdb_single_step) && kgdb_do_roundup)
709 kgdb_roundup_cpus();
710#endif
711
712 /*
713 * Wait for the other CPUs to be notified and be waiting for us:
714 */
715 time_left = MSEC_PER_SEC;
716 while (kgdb_do_roundup && --time_left &&
717 (atomic_read(&masters_in_kgdb) + atomic_read(&slaves_in_kgdb)) !=
718 online_cpus)
719 udelay(1000);
720 if (!time_left)
721 pr_crit("Timed out waiting for secondary CPUs.\n");
722
723 /*
724 * At this point the primary processor is completely
725 * in the debugger and all secondary CPUs are quiescent
726 */
727 dbg_deactivate_sw_breakpoints();
728 kgdb_single_step = 0;
729 kgdb_contthread = current;
730 exception_level = 0;
731 trace_on = tracing_is_on();
732 if (trace_on)
733 tracing_off();
734
735 while (1) {
736cpu_master_loop:
737 if (dbg_kdb_mode) {
738 kgdb_connected = 1;
739 error = kdb_stub(ks);
740 if (error == -1)
741 continue;
742 kgdb_connected = 0;
743 } else {
744 /*
745 * This is a brutal way to interfere with the debugger
746 * and prevent gdb being used to poke at kernel memory.
747 * This could cause trouble if lockdown is applied when
748 * there is already an active gdb session. For now the
749 * answer is simply "don't do that". Typically lockdown
750 * *will* be applied before the debug core gets started
751 * so only developers using kgdb for fairly advanced
752 * early kernel debug can be biten by this. Hopefully
753 * they are sophisticated enough to take care of
754 * themselves, especially with help from the lockdown
755 * message printed on the console!
756 */
757 if (security_locked_down(LOCKDOWN_DBG_WRITE_KERNEL)) {
758 if (IS_ENABLED(CONFIG_KGDB_KDB)) {
759 /* Switch back to kdb if possible... */
760 dbg_kdb_mode = 1;
761 continue;
762 } else {
763 /* ... otherwise just bail */
764 break;
765 }
766 }
767 error = gdb_serial_stub(ks);
768 }
769
770 if (error == DBG_PASS_EVENT) {
771 dbg_kdb_mode = !dbg_kdb_mode;
772 } else if (error == DBG_SWITCH_CPU_EVENT) {
773 kgdb_info[dbg_switch_cpu].exception_state |=
774 DCPU_NEXT_MASTER;
775 goto cpu_loop;
776 } else {
777 kgdb_info[cpu].ret_state = error;
778 break;
779 }
780 }
781
782 dbg_activate_sw_breakpoints();
783
784 /* Call the I/O driver's post_exception routine */
785 if (dbg_io_ops->post_exception)
786 dbg_io_ops->post_exception();
787
788 atomic_dec(&ignore_console_lock_warning);
789
790 if (!kgdb_single_step) {
791 raw_spin_unlock(&dbg_slave_lock);
792 /* Wait till all the CPUs have quit from the debugger. */
793 while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb))
794 cpu_relax();
795 }
796
797kgdb_restore:
798 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
799 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
800 if (kgdb_info[sstep_cpu].task)
801 kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
802 else
803 kgdb_sstep_pid = 0;
804 }
805 if (arch_kgdb_ops.correct_hw_break)
806 arch_kgdb_ops.correct_hw_break();
807 if (trace_on)
808 tracing_on();
809
810 kgdb_info[cpu].debuggerinfo = NULL;
811 kgdb_info[cpu].task = NULL;
812 kgdb_info[cpu].exception_state &=
813 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
814 kgdb_info[cpu].enter_kgdb--;
815 smp_mb__before_atomic();
816 atomic_dec(&masters_in_kgdb);
817 /* Free kgdb_active */
818 atomic_set(&kgdb_active, -1);
819 raw_spin_unlock(&dbg_master_lock);
820 dbg_touch_watchdogs();
821 local_irq_restore(flags);
822 rcu_read_unlock();
823
824 return kgdb_info[cpu].ret_state;
825}
826NOKPROBE_SYMBOL(kgdb_cpu_enter);
827
828/*
829 * kgdb_handle_exception() - main entry point from a kernel exception
830 *
831 * Locking hierarchy:
832 * interface locks, if any (begin_session)
833 * kgdb lock (kgdb_active)
834 */
835int
836kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
837{
838 struct kgdb_state kgdb_var;
839 struct kgdb_state *ks = &kgdb_var;
840 int ret = 0;
841
842 if (arch_kgdb_ops.enable_nmi)
843 arch_kgdb_ops.enable_nmi(0);
844 /*
845 * Avoid entering the debugger if we were triggered due to an oops
846 * but panic_timeout indicates the system should automatically
847 * reboot on panic. We don't want to get stuck waiting for input
848 * on such systems, especially if its "just" an oops.
849 */
850 if (signo != SIGTRAP && panic_timeout)
851 return 1;
852
853 memset(ks, 0, sizeof(struct kgdb_state));
854 ks->cpu = raw_smp_processor_id();
855 ks->ex_vector = evector;
856 ks->signo = signo;
857 ks->err_code = ecode;
858 ks->linux_regs = regs;
859
860 if (kgdb_reenter_check(ks))
861 goto out; /* Ouch, double exception ! */
862 if (kgdb_info[ks->cpu].enter_kgdb != 0)
863 goto out;
864
865 ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
866out:
867 if (arch_kgdb_ops.enable_nmi)
868 arch_kgdb_ops.enable_nmi(1);
869 return ret;
870}
871NOKPROBE_SYMBOL(kgdb_handle_exception);
872
873/*
874 * GDB places a breakpoint at this function to know dynamically loaded objects.
875 */
876static int module_event(struct notifier_block *self, unsigned long val,
877 void *data)
878{
879 return 0;
880}
881
882static struct notifier_block dbg_module_load_nb = {
883 .notifier_call = module_event,
884};
885
886int kgdb_nmicallback(int cpu, void *regs)
887{
888#ifdef CONFIG_SMP
889 struct kgdb_state kgdb_var;
890 struct kgdb_state *ks = &kgdb_var;
891
892 kgdb_info[cpu].rounding_up = false;
893
894 memset(ks, 0, sizeof(struct kgdb_state));
895 ks->cpu = cpu;
896 ks->linux_regs = regs;
897
898 if (kgdb_info[ks->cpu].enter_kgdb == 0 &&
899 raw_spin_is_locked(&dbg_master_lock)) {
900 kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE);
901 return 0;
902 }
903#endif
904 return 1;
905}
906NOKPROBE_SYMBOL(kgdb_nmicallback);
907
908int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code,
909 atomic_t *send_ready)
910{
911#ifdef CONFIG_SMP
912 if (!kgdb_io_ready(0) || !send_ready)
913 return 1;
914
915 if (kgdb_info[cpu].enter_kgdb == 0) {
916 struct kgdb_state kgdb_var;
917 struct kgdb_state *ks = &kgdb_var;
918
919 memset(ks, 0, sizeof(struct kgdb_state));
920 ks->cpu = cpu;
921 ks->ex_vector = trapnr;
922 ks->signo = SIGTRAP;
923 ks->err_code = err_code;
924 ks->linux_regs = regs;
925 ks->send_ready = send_ready;
926 kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
927 return 0;
928 }
929#endif
930 return 1;
931}
932NOKPROBE_SYMBOL(kgdb_nmicallin);
933
934static void kgdb_console_write(struct console *co, const char *s,
935 unsigned count)
936{
937 unsigned long flags;
938
939 /* If we're debugging, or KGDB has not connected, don't try
940 * and print. */
941 if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode)
942 return;
943
944 local_irq_save(flags);
945 gdbstub_msg_write(s, count);
946 local_irq_restore(flags);
947}
948
949static struct console kgdbcons = {
950 .name = "kgdb",
951 .write = kgdb_console_write,
952 .flags = CON_PRINTBUFFER | CON_ENABLED,
953 .index = -1,
954};
955
956static int __init opt_kgdb_con(char *str)
957{
958 kgdb_use_con = 1;
959
960 if (kgdb_io_module_registered && !kgdb_con_registered) {
961 register_console(&kgdbcons);
962 kgdb_con_registered = 1;
963 }
964
965 return 0;
966}
967
968early_param("kgdbcon", opt_kgdb_con);
969
970#ifdef CONFIG_MAGIC_SYSRQ
971static void sysrq_handle_dbg(u8 key)
972{
973 if (!dbg_io_ops) {
974 pr_crit("ERROR: No KGDB I/O module available\n");
975 return;
976 }
977 if (!kgdb_connected) {
978#ifdef CONFIG_KGDB_KDB
979 if (!dbg_kdb_mode)
980 pr_crit("KGDB or $3#33 for KDB\n");
981#else
982 pr_crit("Entering KGDB\n");
983#endif
984 }
985
986 kgdb_breakpoint();
987}
988
989static const struct sysrq_key_op sysrq_dbg_op = {
990 .handler = sysrq_handle_dbg,
991 .help_msg = "debug(g)",
992 .action_msg = "DEBUG",
993};
994#endif
995
996void kgdb_panic(const char *msg)
997{
998 if (!kgdb_io_module_registered)
999 return;
1000
1001 /*
1002 * We don't want to get stuck waiting for input from user if
1003 * "panic_timeout" indicates the system should automatically
1004 * reboot on panic.
1005 */
1006 if (panic_timeout)
1007 return;
1008
1009 debug_locks_off();
1010 console_flush_on_panic(CONSOLE_FLUSH_PENDING);
1011
1012 if (dbg_kdb_mode)
1013 kdb_printf("PANIC: %s\n", msg);
1014
1015 kgdb_breakpoint();
1016}
1017
1018static void kgdb_initial_breakpoint(void)
1019{
1020 kgdb_break_asap = 0;
1021
1022 pr_crit("Waiting for connection from remote gdb...\n");
1023 kgdb_breakpoint();
1024}
1025
1026void __weak kgdb_arch_late(void)
1027{
1028}
1029
1030void __init dbg_late_init(void)
1031{
1032 dbg_is_early = false;
1033 if (kgdb_io_module_registered)
1034 kgdb_arch_late();
1035 kdb_init(KDB_INIT_FULL);
1036
1037 if (kgdb_io_module_registered && kgdb_break_asap)
1038 kgdb_initial_breakpoint();
1039}
1040
1041static int
1042dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x)
1043{
1044 /*
1045 * Take the following action on reboot notify depending on value:
1046 * 1 == Enter debugger
1047 * 0 == [the default] detach debug client
1048 * -1 == Do nothing... and use this until the board resets
1049 */
1050 switch (kgdbreboot) {
1051 case 1:
1052 kgdb_breakpoint();
1053 goto done;
1054 case -1:
1055 goto done;
1056 }
1057 if (!dbg_kdb_mode)
1058 gdbstub_exit(code);
1059done:
1060 return NOTIFY_DONE;
1061}
1062
1063static struct notifier_block dbg_reboot_notifier = {
1064 .notifier_call = dbg_notify_reboot,
1065 .next = NULL,
1066 .priority = INT_MAX,
1067};
1068
1069static void kgdb_register_callbacks(void)
1070{
1071 if (!kgdb_io_module_registered) {
1072 kgdb_io_module_registered = 1;
1073 kgdb_arch_init();
1074 if (!dbg_is_early)
1075 kgdb_arch_late();
1076 register_module_notifier(&dbg_module_load_nb);
1077 register_reboot_notifier(&dbg_reboot_notifier);
1078#ifdef CONFIG_MAGIC_SYSRQ
1079 register_sysrq_key('g', &sysrq_dbg_op);
1080#endif
1081 if (kgdb_use_con && !kgdb_con_registered) {
1082 register_console(&kgdbcons);
1083 kgdb_con_registered = 1;
1084 }
1085 }
1086}
1087
1088static void kgdb_unregister_callbacks(void)
1089{
1090 /*
1091 * When this routine is called KGDB should unregister from
1092 * handlers and clean up, making sure it is not handling any
1093 * break exceptions at the time.
1094 */
1095 if (kgdb_io_module_registered) {
1096 kgdb_io_module_registered = 0;
1097 unregister_reboot_notifier(&dbg_reboot_notifier);
1098 unregister_module_notifier(&dbg_module_load_nb);
1099 kgdb_arch_exit();
1100#ifdef CONFIG_MAGIC_SYSRQ
1101 unregister_sysrq_key('g', &sysrq_dbg_op);
1102#endif
1103 if (kgdb_con_registered) {
1104 unregister_console(&kgdbcons);
1105 kgdb_con_registered = 0;
1106 }
1107 }
1108}
1109
1110/**
1111 * kgdb_register_io_module - register KGDB IO module
1112 * @new_dbg_io_ops: the io ops vector
1113 *
1114 * Register it with the KGDB core.
1115 */
1116int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
1117{
1118 struct kgdb_io *old_dbg_io_ops;
1119 int err;
1120
1121 spin_lock(&kgdb_registration_lock);
1122
1123 old_dbg_io_ops = dbg_io_ops;
1124 if (old_dbg_io_ops) {
1125 if (!old_dbg_io_ops->deinit) {
1126 spin_unlock(&kgdb_registration_lock);
1127
1128 pr_err("KGDB I/O driver %s can't replace %s.\n",
1129 new_dbg_io_ops->name, old_dbg_io_ops->name);
1130 return -EBUSY;
1131 }
1132 pr_info("Replacing I/O driver %s with %s\n",
1133 old_dbg_io_ops->name, new_dbg_io_ops->name);
1134 }
1135
1136 if (new_dbg_io_ops->init) {
1137 err = new_dbg_io_ops->init();
1138 if (err) {
1139 spin_unlock(&kgdb_registration_lock);
1140 return err;
1141 }
1142 }
1143
1144 dbg_io_ops = new_dbg_io_ops;
1145
1146 spin_unlock(&kgdb_registration_lock);
1147
1148 if (old_dbg_io_ops) {
1149 old_dbg_io_ops->deinit();
1150 return 0;
1151 }
1152
1153 pr_info("Registered I/O driver %s\n", new_dbg_io_ops->name);
1154
1155 /* Arm KGDB now. */
1156 kgdb_register_callbacks();
1157
1158 if (kgdb_break_asap &&
1159 (!dbg_is_early || IS_ENABLED(CONFIG_ARCH_HAS_EARLY_DEBUG)))
1160 kgdb_initial_breakpoint();
1161
1162 return 0;
1163}
1164EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1165
1166/**
1167 * kgdb_unregister_io_module - unregister KGDB IO module
1168 * @old_dbg_io_ops: the io ops vector
1169 *
1170 * Unregister it with the KGDB core.
1171 */
1172void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
1173{
1174 BUG_ON(kgdb_connected);
1175
1176 /*
1177 * KGDB is no longer able to communicate out, so
1178 * unregister our callbacks and reset state.
1179 */
1180 kgdb_unregister_callbacks();
1181
1182 spin_lock(&kgdb_registration_lock);
1183
1184 WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops);
1185 dbg_io_ops = NULL;
1186
1187 spin_unlock(&kgdb_registration_lock);
1188
1189 if (old_dbg_io_ops->deinit)
1190 old_dbg_io_ops->deinit();
1191
1192 pr_info("Unregistered I/O driver %s, debugger disabled\n",
1193 old_dbg_io_ops->name);
1194}
1195EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1196
1197int dbg_io_get_char(void)
1198{
1199 int ret = dbg_io_ops->read_char();
1200 if (ret == NO_POLL_CHAR)
1201 return -1;
1202 if (!dbg_kdb_mode)
1203 return ret;
1204 if (ret == 127)
1205 return 8;
1206 return ret;
1207}
1208
1209/**
1210 * kgdb_breakpoint - generate breakpoint exception
1211 *
1212 * This function will generate a breakpoint exception. It is used at the
1213 * beginning of a program to sync up with a debugger and can be used
1214 * otherwise as a quick means to stop program execution and "break" into
1215 * the debugger.
1216 */
1217noinline void kgdb_breakpoint(void)
1218{
1219 atomic_inc(&kgdb_setting_breakpoint);
1220 wmb(); /* Sync point before breakpoint */
1221 arch_kgdb_breakpoint();
1222 wmb(); /* Sync point after breakpoint */
1223 atomic_dec(&kgdb_setting_breakpoint);
1224}
1225EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1226
1227static int __init opt_kgdb_wait(char *str)
1228{
1229 kgdb_break_asap = 1;
1230
1231 kdb_init(KDB_INIT_EARLY);
1232 if (kgdb_io_module_registered &&
1233 IS_ENABLED(CONFIG_ARCH_HAS_EARLY_DEBUG))
1234 kgdb_initial_breakpoint();
1235
1236 return 0;
1237}
1238
1239early_param("kgdbwait", opt_kgdb_wait);
1/*
2 * Kernel Debug Core
3 *
4 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
5 *
6 * Copyright (C) 2000-2001 VERITAS Software Corporation.
7 * Copyright (C) 2002-2004 Timesys Corporation
8 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
9 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
10 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
11 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
12 * Copyright (C) 2005-2009 Wind River Systems, Inc.
13 * Copyright (C) 2007 MontaVista Software, Inc.
14 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
15 *
16 * Contributors at various stages not listed above:
17 * Jason Wessel ( jason.wessel@windriver.com )
18 * George Anzinger <george@mvista.com>
19 * Anurekh Saxena (anurekh.saxena@timesys.com)
20 * Lake Stevens Instrument Division (Glenn Engel)
21 * Jim Kingdon, Cygnus Support.
22 *
23 * Original KGDB stub: David Grothe <dave@gcom.com>,
24 * Tigran Aivazian <tigran@sco.com>
25 *
26 * This file is licensed under the terms of the GNU General Public License
27 * version 2. This program is licensed "as is" without any warranty of any
28 * kind, whether express or implied.
29 */
30#include <linux/pid_namespace.h>
31#include <linux/clocksource.h>
32#include <linux/interrupt.h>
33#include <linux/spinlock.h>
34#include <linux/console.h>
35#include <linux/threads.h>
36#include <linux/uaccess.h>
37#include <linux/kernel.h>
38#include <linux/module.h>
39#include <linux/ptrace.h>
40#include <linux/string.h>
41#include <linux/delay.h>
42#include <linux/sched.h>
43#include <linux/sysrq.h>
44#include <linux/init.h>
45#include <linux/kgdb.h>
46#include <linux/kdb.h>
47#include <linux/pid.h>
48#include <linux/smp.h>
49#include <linux/mm.h>
50#include <linux/rcupdate.h>
51
52#include <asm/cacheflush.h>
53#include <asm/byteorder.h>
54#include <linux/atomic.h>
55#include <asm/system.h>
56
57#include "debug_core.h"
58
59static int kgdb_break_asap;
60
61struct debuggerinfo_struct kgdb_info[NR_CPUS];
62
63/**
64 * kgdb_connected - Is a host GDB connected to us?
65 */
66int kgdb_connected;
67EXPORT_SYMBOL_GPL(kgdb_connected);
68
69/* All the KGDB handlers are installed */
70int kgdb_io_module_registered;
71
72/* Guard for recursive entry */
73static int exception_level;
74
75struct kgdb_io *dbg_io_ops;
76static DEFINE_SPINLOCK(kgdb_registration_lock);
77
78/* kgdb console driver is loaded */
79static int kgdb_con_registered;
80/* determine if kgdb console output should be used */
81static int kgdb_use_con;
82/* Flag for alternate operations for early debugging */
83bool dbg_is_early = true;
84/* Next cpu to become the master debug core */
85int dbg_switch_cpu;
86
87/* Use kdb or gdbserver mode */
88int dbg_kdb_mode = 1;
89
90static int __init opt_kgdb_con(char *str)
91{
92 kgdb_use_con = 1;
93 return 0;
94}
95
96early_param("kgdbcon", opt_kgdb_con);
97
98module_param(kgdb_use_con, int, 0644);
99
100/*
101 * Holds information about breakpoints in a kernel. These breakpoints are
102 * added and removed by gdb.
103 */
104static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
105 [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
106};
107
108/*
109 * The CPU# of the active CPU, or -1 if none:
110 */
111atomic_t kgdb_active = ATOMIC_INIT(-1);
112EXPORT_SYMBOL_GPL(kgdb_active);
113static DEFINE_RAW_SPINLOCK(dbg_master_lock);
114static DEFINE_RAW_SPINLOCK(dbg_slave_lock);
115
116/*
117 * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
118 * bootup code (which might not have percpu set up yet):
119 */
120static atomic_t masters_in_kgdb;
121static atomic_t slaves_in_kgdb;
122static atomic_t kgdb_break_tasklet_var;
123atomic_t kgdb_setting_breakpoint;
124
125struct task_struct *kgdb_usethread;
126struct task_struct *kgdb_contthread;
127
128int kgdb_single_step;
129static pid_t kgdb_sstep_pid;
130
131/* to keep track of the CPU which is doing the single stepping*/
132atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
133
134/*
135 * If you are debugging a problem where roundup (the collection of
136 * all other CPUs) is a problem [this should be extremely rare],
137 * then use the nokgdbroundup option to avoid roundup. In that case
138 * the other CPUs might interfere with your debugging context, so
139 * use this with care:
140 */
141static int kgdb_do_roundup = 1;
142
143static int __init opt_nokgdbroundup(char *str)
144{
145 kgdb_do_roundup = 0;
146
147 return 0;
148}
149
150early_param("nokgdbroundup", opt_nokgdbroundup);
151
152/*
153 * Finally, some KGDB code :-)
154 */
155
156/*
157 * Weak aliases for breakpoint management,
158 * can be overriden by architectures when needed:
159 */
160int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
161{
162 int err;
163
164 err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
165 if (err)
166 return err;
167
168 return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
169 BREAK_INSTR_SIZE);
170}
171
172int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
173{
174 return probe_kernel_write((char *)addr,
175 (char *)bundle, BREAK_INSTR_SIZE);
176}
177
178int __weak kgdb_validate_break_address(unsigned long addr)
179{
180 char tmp_variable[BREAK_INSTR_SIZE];
181 int err;
182 /* Validate setting the breakpoint and then removing it. In the
183 * remove fails, the kernel needs to emit a bad message because we
184 * are deep trouble not being able to put things back the way we
185 * found them.
186 */
187 err = kgdb_arch_set_breakpoint(addr, tmp_variable);
188 if (err)
189 return err;
190 err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
191 if (err)
192 printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
193 "memory destroyed at: %lx", addr);
194 return err;
195}
196
197unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
198{
199 return instruction_pointer(regs);
200}
201
202int __weak kgdb_arch_init(void)
203{
204 return 0;
205}
206
207int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
208{
209 return 0;
210}
211
212/*
213 * Some architectures need cache flushes when we set/clear a
214 * breakpoint:
215 */
216static void kgdb_flush_swbreak_addr(unsigned long addr)
217{
218 if (!CACHE_FLUSH_IS_SAFE)
219 return;
220
221 if (current->mm && current->mm->mmap_cache) {
222 flush_cache_range(current->mm->mmap_cache,
223 addr, addr + BREAK_INSTR_SIZE);
224 }
225 /* Force flush instruction cache if it was outside the mm */
226 flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
227}
228
229/*
230 * SW breakpoint management:
231 */
232int dbg_activate_sw_breakpoints(void)
233{
234 unsigned long addr;
235 int error;
236 int ret = 0;
237 int i;
238
239 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
240 if (kgdb_break[i].state != BP_SET)
241 continue;
242
243 addr = kgdb_break[i].bpt_addr;
244 error = kgdb_arch_set_breakpoint(addr,
245 kgdb_break[i].saved_instr);
246 if (error) {
247 ret = error;
248 printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
249 continue;
250 }
251
252 kgdb_flush_swbreak_addr(addr);
253 kgdb_break[i].state = BP_ACTIVE;
254 }
255 return ret;
256}
257
258int dbg_set_sw_break(unsigned long addr)
259{
260 int err = kgdb_validate_break_address(addr);
261 int breakno = -1;
262 int i;
263
264 if (err)
265 return err;
266
267 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
268 if ((kgdb_break[i].state == BP_SET) &&
269 (kgdb_break[i].bpt_addr == addr))
270 return -EEXIST;
271 }
272 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
273 if (kgdb_break[i].state == BP_REMOVED &&
274 kgdb_break[i].bpt_addr == addr) {
275 breakno = i;
276 break;
277 }
278 }
279
280 if (breakno == -1) {
281 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
282 if (kgdb_break[i].state == BP_UNDEFINED) {
283 breakno = i;
284 break;
285 }
286 }
287 }
288
289 if (breakno == -1)
290 return -E2BIG;
291
292 kgdb_break[breakno].state = BP_SET;
293 kgdb_break[breakno].type = BP_BREAKPOINT;
294 kgdb_break[breakno].bpt_addr = addr;
295
296 return 0;
297}
298
299int dbg_deactivate_sw_breakpoints(void)
300{
301 unsigned long addr;
302 int error;
303 int ret = 0;
304 int i;
305
306 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
307 if (kgdb_break[i].state != BP_ACTIVE)
308 continue;
309 addr = kgdb_break[i].bpt_addr;
310 error = kgdb_arch_remove_breakpoint(addr,
311 kgdb_break[i].saved_instr);
312 if (error) {
313 printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
314 ret = error;
315 }
316
317 kgdb_flush_swbreak_addr(addr);
318 kgdb_break[i].state = BP_SET;
319 }
320 return ret;
321}
322
323int dbg_remove_sw_break(unsigned long addr)
324{
325 int i;
326
327 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
328 if ((kgdb_break[i].state == BP_SET) &&
329 (kgdb_break[i].bpt_addr == addr)) {
330 kgdb_break[i].state = BP_REMOVED;
331 return 0;
332 }
333 }
334 return -ENOENT;
335}
336
337int kgdb_isremovedbreak(unsigned long addr)
338{
339 int i;
340
341 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
342 if ((kgdb_break[i].state == BP_REMOVED) &&
343 (kgdb_break[i].bpt_addr == addr))
344 return 1;
345 }
346 return 0;
347}
348
349int dbg_remove_all_break(void)
350{
351 unsigned long addr;
352 int error;
353 int i;
354
355 /* Clear memory breakpoints. */
356 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
357 if (kgdb_break[i].state != BP_ACTIVE)
358 goto setundefined;
359 addr = kgdb_break[i].bpt_addr;
360 error = kgdb_arch_remove_breakpoint(addr,
361 kgdb_break[i].saved_instr);
362 if (error)
363 printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
364 addr);
365setundefined:
366 kgdb_break[i].state = BP_UNDEFINED;
367 }
368
369 /* Clear hardware breakpoints. */
370 if (arch_kgdb_ops.remove_all_hw_break)
371 arch_kgdb_ops.remove_all_hw_break();
372
373 return 0;
374}
375
376/*
377 * Return true if there is a valid kgdb I/O module. Also if no
378 * debugger is attached a message can be printed to the console about
379 * waiting for the debugger to attach.
380 *
381 * The print_wait argument is only to be true when called from inside
382 * the core kgdb_handle_exception, because it will wait for the
383 * debugger to attach.
384 */
385static int kgdb_io_ready(int print_wait)
386{
387 if (!dbg_io_ops)
388 return 0;
389 if (kgdb_connected)
390 return 1;
391 if (atomic_read(&kgdb_setting_breakpoint))
392 return 1;
393 if (print_wait) {
394#ifdef CONFIG_KGDB_KDB
395 if (!dbg_kdb_mode)
396 printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n");
397#else
398 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
399#endif
400 }
401 return 1;
402}
403
404static int kgdb_reenter_check(struct kgdb_state *ks)
405{
406 unsigned long addr;
407
408 if (atomic_read(&kgdb_active) != raw_smp_processor_id())
409 return 0;
410
411 /* Panic on recursive debugger calls: */
412 exception_level++;
413 addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
414 dbg_deactivate_sw_breakpoints();
415
416 /*
417 * If the break point removed ok at the place exception
418 * occurred, try to recover and print a warning to the end
419 * user because the user planted a breakpoint in a place that
420 * KGDB needs in order to function.
421 */
422 if (dbg_remove_sw_break(addr) == 0) {
423 exception_level = 0;
424 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
425 dbg_activate_sw_breakpoints();
426 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
427 addr);
428 WARN_ON_ONCE(1);
429
430 return 1;
431 }
432 dbg_remove_all_break();
433 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
434
435 if (exception_level > 1) {
436 dump_stack();
437 panic("Recursive entry to debugger");
438 }
439
440 printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
441#ifdef CONFIG_KGDB_KDB
442 /* Allow kdb to debug itself one level */
443 return 0;
444#endif
445 dump_stack();
446 panic("Recursive entry to debugger");
447
448 return 1;
449}
450
451static void dbg_touch_watchdogs(void)
452{
453 touch_softlockup_watchdog_sync();
454 clocksource_touch_watchdog();
455 rcu_cpu_stall_reset();
456}
457
458static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
459 int exception_state)
460{
461 unsigned long flags;
462 int sstep_tries = 100;
463 int error;
464 int cpu;
465 int trace_on = 0;
466 int online_cpus = num_online_cpus();
467
468 kgdb_info[ks->cpu].enter_kgdb++;
469 kgdb_info[ks->cpu].exception_state |= exception_state;
470
471 if (exception_state == DCPU_WANT_MASTER)
472 atomic_inc(&masters_in_kgdb);
473 else
474 atomic_inc(&slaves_in_kgdb);
475
476 if (arch_kgdb_ops.disable_hw_break)
477 arch_kgdb_ops.disable_hw_break(regs);
478
479acquirelock:
480 /*
481 * Interrupts will be restored by the 'trap return' code, except when
482 * single stepping.
483 */
484 local_irq_save(flags);
485
486 cpu = ks->cpu;
487 kgdb_info[cpu].debuggerinfo = regs;
488 kgdb_info[cpu].task = current;
489 kgdb_info[cpu].ret_state = 0;
490 kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT;
491
492 /* Make sure the above info reaches the primary CPU */
493 smp_mb();
494
495 if (exception_level == 1) {
496 if (raw_spin_trylock(&dbg_master_lock))
497 atomic_xchg(&kgdb_active, cpu);
498 goto cpu_master_loop;
499 }
500
501 /*
502 * CPU will loop if it is a slave or request to become a kgdb
503 * master cpu and acquire the kgdb_active lock:
504 */
505 while (1) {
506cpu_loop:
507 if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) {
508 kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER;
509 goto cpu_master_loop;
510 } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
511 if (raw_spin_trylock(&dbg_master_lock)) {
512 atomic_xchg(&kgdb_active, cpu);
513 break;
514 }
515 } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
516 if (!raw_spin_is_locked(&dbg_slave_lock))
517 goto return_normal;
518 } else {
519return_normal:
520 /* Return to normal operation by executing any
521 * hw breakpoint fixup.
522 */
523 if (arch_kgdb_ops.correct_hw_break)
524 arch_kgdb_ops.correct_hw_break();
525 if (trace_on)
526 tracing_on();
527 kgdb_info[cpu].exception_state &=
528 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
529 kgdb_info[cpu].enter_kgdb--;
530 smp_mb__before_atomic_dec();
531 atomic_dec(&slaves_in_kgdb);
532 dbg_touch_watchdogs();
533 local_irq_restore(flags);
534 return 0;
535 }
536 cpu_relax();
537 }
538
539 /*
540 * For single stepping, try to only enter on the processor
541 * that was single stepping. To guard against a deadlock, the
542 * kernel will only try for the value of sstep_tries before
543 * giving up and continuing on.
544 */
545 if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
546 (kgdb_info[cpu].task &&
547 kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
548 atomic_set(&kgdb_active, -1);
549 raw_spin_unlock(&dbg_master_lock);
550 dbg_touch_watchdogs();
551 local_irq_restore(flags);
552
553 goto acquirelock;
554 }
555
556 if (!kgdb_io_ready(1)) {
557 kgdb_info[cpu].ret_state = 1;
558 goto kgdb_restore; /* No I/O connection, resume the system */
559 }
560
561 /*
562 * Don't enter if we have hit a removed breakpoint.
563 */
564 if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
565 goto kgdb_restore;
566
567 /* Call the I/O driver's pre_exception routine */
568 if (dbg_io_ops->pre_exception)
569 dbg_io_ops->pre_exception();
570
571 /*
572 * Get the passive CPU lock which will hold all the non-primary
573 * CPU in a spin state while the debugger is active
574 */
575 if (!kgdb_single_step)
576 raw_spin_lock(&dbg_slave_lock);
577
578#ifdef CONFIG_SMP
579 /* Signal the other CPUs to enter kgdb_wait() */
580 if ((!kgdb_single_step) && kgdb_do_roundup)
581 kgdb_roundup_cpus(flags);
582#endif
583
584 /*
585 * Wait for the other CPUs to be notified and be waiting for us:
586 */
587 while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) +
588 atomic_read(&slaves_in_kgdb)) != online_cpus)
589 cpu_relax();
590
591 /*
592 * At this point the primary processor is completely
593 * in the debugger and all secondary CPUs are quiescent
594 */
595 dbg_deactivate_sw_breakpoints();
596 kgdb_single_step = 0;
597 kgdb_contthread = current;
598 exception_level = 0;
599 trace_on = tracing_is_on();
600 if (trace_on)
601 tracing_off();
602
603 while (1) {
604cpu_master_loop:
605 if (dbg_kdb_mode) {
606 kgdb_connected = 1;
607 error = kdb_stub(ks);
608 if (error == -1)
609 continue;
610 kgdb_connected = 0;
611 } else {
612 error = gdb_serial_stub(ks);
613 }
614
615 if (error == DBG_PASS_EVENT) {
616 dbg_kdb_mode = !dbg_kdb_mode;
617 } else if (error == DBG_SWITCH_CPU_EVENT) {
618 kgdb_info[dbg_switch_cpu].exception_state |=
619 DCPU_NEXT_MASTER;
620 goto cpu_loop;
621 } else {
622 kgdb_info[cpu].ret_state = error;
623 break;
624 }
625 }
626
627 /* Call the I/O driver's post_exception routine */
628 if (dbg_io_ops->post_exception)
629 dbg_io_ops->post_exception();
630
631 if (!kgdb_single_step) {
632 raw_spin_unlock(&dbg_slave_lock);
633 /* Wait till all the CPUs have quit from the debugger. */
634 while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb))
635 cpu_relax();
636 }
637
638kgdb_restore:
639 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
640 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
641 if (kgdb_info[sstep_cpu].task)
642 kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
643 else
644 kgdb_sstep_pid = 0;
645 }
646 if (arch_kgdb_ops.correct_hw_break)
647 arch_kgdb_ops.correct_hw_break();
648 if (trace_on)
649 tracing_on();
650
651 kgdb_info[cpu].exception_state &=
652 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
653 kgdb_info[cpu].enter_kgdb--;
654 smp_mb__before_atomic_dec();
655 atomic_dec(&masters_in_kgdb);
656 /* Free kgdb_active */
657 atomic_set(&kgdb_active, -1);
658 raw_spin_unlock(&dbg_master_lock);
659 dbg_touch_watchdogs();
660 local_irq_restore(flags);
661
662 return kgdb_info[cpu].ret_state;
663}
664
665/*
666 * kgdb_handle_exception() - main entry point from a kernel exception
667 *
668 * Locking hierarchy:
669 * interface locks, if any (begin_session)
670 * kgdb lock (kgdb_active)
671 */
672int
673kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
674{
675 struct kgdb_state kgdb_var;
676 struct kgdb_state *ks = &kgdb_var;
677
678 ks->cpu = raw_smp_processor_id();
679 ks->ex_vector = evector;
680 ks->signo = signo;
681 ks->err_code = ecode;
682 ks->kgdb_usethreadid = 0;
683 ks->linux_regs = regs;
684
685 if (kgdb_reenter_check(ks))
686 return 0; /* Ouch, double exception ! */
687 if (kgdb_info[ks->cpu].enter_kgdb != 0)
688 return 0;
689
690 return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
691}
692
693int kgdb_nmicallback(int cpu, void *regs)
694{
695#ifdef CONFIG_SMP
696 struct kgdb_state kgdb_var;
697 struct kgdb_state *ks = &kgdb_var;
698
699 memset(ks, 0, sizeof(struct kgdb_state));
700 ks->cpu = cpu;
701 ks->linux_regs = regs;
702
703 if (kgdb_info[ks->cpu].enter_kgdb == 0 &&
704 raw_spin_is_locked(&dbg_master_lock)) {
705 kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE);
706 return 0;
707 }
708#endif
709 return 1;
710}
711
712static void kgdb_console_write(struct console *co, const char *s,
713 unsigned count)
714{
715 unsigned long flags;
716
717 /* If we're debugging, or KGDB has not connected, don't try
718 * and print. */
719 if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode)
720 return;
721
722 local_irq_save(flags);
723 gdbstub_msg_write(s, count);
724 local_irq_restore(flags);
725}
726
727static struct console kgdbcons = {
728 .name = "kgdb",
729 .write = kgdb_console_write,
730 .flags = CON_PRINTBUFFER | CON_ENABLED,
731 .index = -1,
732};
733
734#ifdef CONFIG_MAGIC_SYSRQ
735static void sysrq_handle_dbg(int key)
736{
737 if (!dbg_io_ops) {
738 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
739 return;
740 }
741 if (!kgdb_connected) {
742#ifdef CONFIG_KGDB_KDB
743 if (!dbg_kdb_mode)
744 printk(KERN_CRIT "KGDB or $3#33 for KDB\n");
745#else
746 printk(KERN_CRIT "Entering KGDB\n");
747#endif
748 }
749
750 kgdb_breakpoint();
751}
752
753static struct sysrq_key_op sysrq_dbg_op = {
754 .handler = sysrq_handle_dbg,
755 .help_msg = "debug(G)",
756 .action_msg = "DEBUG",
757};
758#endif
759
760static int kgdb_panic_event(struct notifier_block *self,
761 unsigned long val,
762 void *data)
763{
764 if (dbg_kdb_mode)
765 kdb_printf("PANIC: %s\n", (char *)data);
766 kgdb_breakpoint();
767 return NOTIFY_DONE;
768}
769
770static struct notifier_block kgdb_panic_event_nb = {
771 .notifier_call = kgdb_panic_event,
772 .priority = INT_MAX,
773};
774
775void __weak kgdb_arch_late(void)
776{
777}
778
779void __init dbg_late_init(void)
780{
781 dbg_is_early = false;
782 if (kgdb_io_module_registered)
783 kgdb_arch_late();
784 kdb_init(KDB_INIT_FULL);
785}
786
787static void kgdb_register_callbacks(void)
788{
789 if (!kgdb_io_module_registered) {
790 kgdb_io_module_registered = 1;
791 kgdb_arch_init();
792 if (!dbg_is_early)
793 kgdb_arch_late();
794 atomic_notifier_chain_register(&panic_notifier_list,
795 &kgdb_panic_event_nb);
796#ifdef CONFIG_MAGIC_SYSRQ
797 register_sysrq_key('g', &sysrq_dbg_op);
798#endif
799 if (kgdb_use_con && !kgdb_con_registered) {
800 register_console(&kgdbcons);
801 kgdb_con_registered = 1;
802 }
803 }
804}
805
806static void kgdb_unregister_callbacks(void)
807{
808 /*
809 * When this routine is called KGDB should unregister from the
810 * panic handler and clean up, making sure it is not handling any
811 * break exceptions at the time.
812 */
813 if (kgdb_io_module_registered) {
814 kgdb_io_module_registered = 0;
815 atomic_notifier_chain_unregister(&panic_notifier_list,
816 &kgdb_panic_event_nb);
817 kgdb_arch_exit();
818#ifdef CONFIG_MAGIC_SYSRQ
819 unregister_sysrq_key('g', &sysrq_dbg_op);
820#endif
821 if (kgdb_con_registered) {
822 unregister_console(&kgdbcons);
823 kgdb_con_registered = 0;
824 }
825 }
826}
827
828/*
829 * There are times a tasklet needs to be used vs a compiled in
830 * break point so as to cause an exception outside a kgdb I/O module,
831 * such as is the case with kgdboe, where calling a breakpoint in the
832 * I/O driver itself would be fatal.
833 */
834static void kgdb_tasklet_bpt(unsigned long ing)
835{
836 kgdb_breakpoint();
837 atomic_set(&kgdb_break_tasklet_var, 0);
838}
839
840static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0);
841
842void kgdb_schedule_breakpoint(void)
843{
844 if (atomic_read(&kgdb_break_tasklet_var) ||
845 atomic_read(&kgdb_active) != -1 ||
846 atomic_read(&kgdb_setting_breakpoint))
847 return;
848 atomic_inc(&kgdb_break_tasklet_var);
849 tasklet_schedule(&kgdb_tasklet_breakpoint);
850}
851EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint);
852
853static void kgdb_initial_breakpoint(void)
854{
855 kgdb_break_asap = 0;
856
857 printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
858 kgdb_breakpoint();
859}
860
861/**
862 * kgdb_register_io_module - register KGDB IO module
863 * @new_dbg_io_ops: the io ops vector
864 *
865 * Register it with the KGDB core.
866 */
867int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
868{
869 int err;
870
871 spin_lock(&kgdb_registration_lock);
872
873 if (dbg_io_ops) {
874 spin_unlock(&kgdb_registration_lock);
875
876 printk(KERN_ERR "kgdb: Another I/O driver is already "
877 "registered with KGDB.\n");
878 return -EBUSY;
879 }
880
881 if (new_dbg_io_ops->init) {
882 err = new_dbg_io_ops->init();
883 if (err) {
884 spin_unlock(&kgdb_registration_lock);
885 return err;
886 }
887 }
888
889 dbg_io_ops = new_dbg_io_ops;
890
891 spin_unlock(&kgdb_registration_lock);
892
893 printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
894 new_dbg_io_ops->name);
895
896 /* Arm KGDB now. */
897 kgdb_register_callbacks();
898
899 if (kgdb_break_asap)
900 kgdb_initial_breakpoint();
901
902 return 0;
903}
904EXPORT_SYMBOL_GPL(kgdb_register_io_module);
905
906/**
907 * kkgdb_unregister_io_module - unregister KGDB IO module
908 * @old_dbg_io_ops: the io ops vector
909 *
910 * Unregister it with the KGDB core.
911 */
912void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
913{
914 BUG_ON(kgdb_connected);
915
916 /*
917 * KGDB is no longer able to communicate out, so
918 * unregister our callbacks and reset state.
919 */
920 kgdb_unregister_callbacks();
921
922 spin_lock(&kgdb_registration_lock);
923
924 WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops);
925 dbg_io_ops = NULL;
926
927 spin_unlock(&kgdb_registration_lock);
928
929 printk(KERN_INFO
930 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
931 old_dbg_io_ops->name);
932}
933EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
934
935int dbg_io_get_char(void)
936{
937 int ret = dbg_io_ops->read_char();
938 if (ret == NO_POLL_CHAR)
939 return -1;
940 if (!dbg_kdb_mode)
941 return ret;
942 if (ret == 127)
943 return 8;
944 return ret;
945}
946
947/**
948 * kgdb_breakpoint - generate breakpoint exception
949 *
950 * This function will generate a breakpoint exception. It is used at the
951 * beginning of a program to sync up with a debugger and can be used
952 * otherwise as a quick means to stop program execution and "break" into
953 * the debugger.
954 */
955void kgdb_breakpoint(void)
956{
957 atomic_inc(&kgdb_setting_breakpoint);
958 wmb(); /* Sync point before breakpoint */
959 arch_kgdb_breakpoint();
960 wmb(); /* Sync point after breakpoint */
961 atomic_dec(&kgdb_setting_breakpoint);
962}
963EXPORT_SYMBOL_GPL(kgdb_breakpoint);
964
965static int __init opt_kgdb_wait(char *str)
966{
967 kgdb_break_asap = 1;
968
969 kdb_init(KDB_INIT_EARLY);
970 if (kgdb_io_module_registered)
971 kgdb_initial_breakpoint();
972
973 return 0;
974}
975
976early_param("kgdbwait", opt_kgdb_wait);