projects/linux·blob 0785a8e8 · refs

976 lines · 22.7 KiB

1/*
2 * Kernel Debug Core
3 *
4 * Maintainer: Jason Wessel <[email protected]>
5 *
6 * Copyright (C) 2000-2001 VERITAS Software Corporation.
7 * Copyright (C) 2002-2004 Timesys Corporation
8 * Copyright (C) 2003-2004 Amit S. Kale <[email protected]>
9 * Copyright (C) 2004 Pavel Machek <[email protected]>
10 * Copyright (C) 2004-2006 Tom Rini <[email protected]>
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 <[email protected]>
15 *
16 * Contributors at various stages not listed above:
17 * Jason Wessel ( [email protected] )
18 * George Anzinger <[email protected]>
19 * Anurekh Saxena ([email protected])
20 * Lake Stevens Instrument Division (Glenn Engel)
21 * Jim Kingdon, Cygnus Support.
22 *
23 * Original KGDB stub: David Grothe <[email protected]>,
24 * Tigran Aivazian <[email protected]>
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);