4 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
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>
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.
23 * Original KGDB stub: David Grothe <dave@gcom.com>,
24 * Tigran Aivazian <tigran@sco.com>
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.
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/reboot.h>
45 #include <linux/init.h>
46 #include <linux/kgdb.h>
47 #include <linux/kdb.h>
48 #include <linux/pid.h>
49 #include <linux/smp.h>
51 #include <linux/rcupdate.h>
53 #include <asm/cacheflush.h>
54 #include <asm/byteorder.h>
55 #include <linux/atomic.h>
57 #include "debug_core.h"
59 static int kgdb_break_asap;
61 struct debuggerinfo_struct kgdb_info[NR_CPUS];
64 * kgdb_connected - Is a host GDB connected to us?
67 EXPORT_SYMBOL_GPL(kgdb_connected);
69 /* All the KGDB handlers are installed */
70 int kgdb_io_module_registered;
72 /* Guard for recursive entry */
73 static int exception_level;
75 struct kgdb_io *dbg_io_ops;
76 static DEFINE_SPINLOCK(kgdb_registration_lock);
78 /* Action for the reboot notifiter, a global allow kdb to change it */
79 static int kgdbreboot;
80 /* kgdb console driver is loaded */
81 static int kgdb_con_registered;
82 /* determine if kgdb console output should be used */
83 static int kgdb_use_con;
84 /* Flag for alternate operations for early debugging */
85 bool dbg_is_early = true;
86 /* Next cpu to become the master debug core */
89 /* Use kdb or gdbserver mode */
92 static int __init opt_kgdb_con(char *str)
98 early_param("kgdbcon", opt_kgdb_con);
100 module_param(kgdb_use_con, int, 0644);
101 module_param(kgdbreboot, int, 0644);
104 * Holds information about breakpoints in a kernel. These breakpoints are
105 * added and removed by gdb.
107 static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
108 [0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
112 * The CPU# of the active CPU, or -1 if none:
114 atomic_t kgdb_active = ATOMIC_INIT(-1);
115 EXPORT_SYMBOL_GPL(kgdb_active);
116 static DEFINE_RAW_SPINLOCK(dbg_master_lock);
117 static DEFINE_RAW_SPINLOCK(dbg_slave_lock);
120 * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
121 * bootup code (which might not have percpu set up yet):
123 static atomic_t masters_in_kgdb;
124 static atomic_t slaves_in_kgdb;
125 static atomic_t kgdb_break_tasklet_var;
126 atomic_t kgdb_setting_breakpoint;
128 struct task_struct *kgdb_usethread;
129 struct task_struct *kgdb_contthread;
131 int kgdb_single_step;
132 static pid_t kgdb_sstep_pid;
134 /* to keep track of the CPU which is doing the single stepping*/
135 atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
138 * If you are debugging a problem where roundup (the collection of
139 * all other CPUs) is a problem [this should be extremely rare],
140 * then use the nokgdbroundup option to avoid roundup. In that case
141 * the other CPUs might interfere with your debugging context, so
142 * use this with care:
144 static int kgdb_do_roundup = 1;
146 static int __init opt_nokgdbroundup(char *str)
153 early_param("nokgdbroundup", opt_nokgdbroundup);
156 * Finally, some KGDB code :-)
160 * Weak aliases for breakpoint management,
161 * can be overriden by architectures when needed:
163 int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
167 err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
171 return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
175 int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
177 return probe_kernel_write((char *)addr,
178 (char *)bundle, BREAK_INSTR_SIZE);
181 int __weak kgdb_validate_break_address(unsigned long addr)
183 char tmp_variable[BREAK_INSTR_SIZE];
185 /* Validate setting the breakpoint and then removing it. In 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
190 err = kgdb_arch_set_breakpoint(addr, tmp_variable);
193 err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
195 printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
196 "memory destroyed at: %lx", addr);
200 unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
202 return instruction_pointer(regs);
205 int __weak kgdb_arch_init(void)
210 int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
216 * Some architectures need cache flushes when we set/clear a
219 static void kgdb_flush_swbreak_addr(unsigned long addr)
221 if (!CACHE_FLUSH_IS_SAFE)
224 if (current->mm && current->mm->mmap_cache) {
225 flush_cache_range(current->mm->mmap_cache,
226 addr, addr + BREAK_INSTR_SIZE);
228 /* Force flush instruction cache if it was outside the mm */
229 flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
233 * SW breakpoint management:
235 int dbg_activate_sw_breakpoints(void)
242 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
243 if (kgdb_break[i].state != BP_SET)
246 addr = kgdb_break[i].bpt_addr;
247 error = kgdb_arch_set_breakpoint(addr,
248 kgdb_break[i].saved_instr);
251 printk(KERN_INFO "KGDB: BP install failed: %lx", addr);
255 kgdb_flush_swbreak_addr(addr);
256 kgdb_break[i].state = BP_ACTIVE;
261 int dbg_set_sw_break(unsigned long addr)
263 int err = kgdb_validate_break_address(addr);
270 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
271 if ((kgdb_break[i].state == BP_SET) &&
272 (kgdb_break[i].bpt_addr == addr))
275 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
276 if (kgdb_break[i].state == BP_REMOVED &&
277 kgdb_break[i].bpt_addr == addr) {
284 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
285 if (kgdb_break[i].state == BP_UNDEFINED) {
295 kgdb_break[breakno].state = BP_SET;
296 kgdb_break[breakno].type = BP_BREAKPOINT;
297 kgdb_break[breakno].bpt_addr = addr;
302 int dbg_deactivate_sw_breakpoints(void)
309 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
310 if (kgdb_break[i].state != BP_ACTIVE)
312 addr = kgdb_break[i].bpt_addr;
313 error = kgdb_arch_remove_breakpoint(addr,
314 kgdb_break[i].saved_instr);
316 printk(KERN_INFO "KGDB: BP remove failed: %lx\n", addr);
320 kgdb_flush_swbreak_addr(addr);
321 kgdb_break[i].state = BP_SET;
326 int dbg_remove_sw_break(unsigned long addr)
330 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
331 if ((kgdb_break[i].state == BP_SET) &&
332 (kgdb_break[i].bpt_addr == addr)) {
333 kgdb_break[i].state = BP_REMOVED;
340 int kgdb_isremovedbreak(unsigned long addr)
344 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
345 if ((kgdb_break[i].state == BP_REMOVED) &&
346 (kgdb_break[i].bpt_addr == addr))
352 int dbg_remove_all_break(void)
358 /* Clear memory breakpoints. */
359 for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
360 if (kgdb_break[i].state != BP_ACTIVE)
362 addr = kgdb_break[i].bpt_addr;
363 error = kgdb_arch_remove_breakpoint(addr,
364 kgdb_break[i].saved_instr);
366 printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
369 kgdb_break[i].state = BP_UNDEFINED;
372 /* Clear hardware breakpoints. */
373 if (arch_kgdb_ops.remove_all_hw_break)
374 arch_kgdb_ops.remove_all_hw_break();
380 * Return true if there is a valid kgdb I/O module. Also if no
381 * debugger is attached a message can be printed to the console about
382 * waiting for the debugger to attach.
384 * The print_wait argument is only to be true when called from inside
385 * the core kgdb_handle_exception, because it will wait for the
386 * debugger to attach.
388 static int kgdb_io_ready(int print_wait)
394 if (atomic_read(&kgdb_setting_breakpoint))
397 #ifdef CONFIG_KGDB_KDB
399 printk(KERN_CRIT "KGDB: waiting... or $3#33 for KDB\n");
401 printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
407 static int kgdb_reenter_check(struct kgdb_state *ks)
411 if (atomic_read(&kgdb_active) != raw_smp_processor_id())
414 /* Panic on recursive debugger calls: */
416 addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
417 dbg_deactivate_sw_breakpoints();
420 * If the break point removed ok at the place exception
421 * occurred, try to recover and print a warning to the end
422 * user because the user planted a breakpoint in a place that
423 * KGDB needs in order to function.
425 if (dbg_remove_sw_break(addr) == 0) {
427 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
428 dbg_activate_sw_breakpoints();
429 printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
435 dbg_remove_all_break();
436 kgdb_skipexception(ks->ex_vector, ks->linux_regs);
438 if (exception_level > 1) {
440 panic("Recursive entry to debugger");
443 printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
444 #ifdef CONFIG_KGDB_KDB
445 /* Allow kdb to debug itself one level */
449 panic("Recursive entry to debugger");
454 static void dbg_touch_watchdogs(void)
456 touch_softlockup_watchdog_sync();
457 clocksource_touch_watchdog();
458 rcu_cpu_stall_reset();
461 static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
465 int sstep_tries = 100;
469 int online_cpus = num_online_cpus();
471 kgdb_info[ks->cpu].enter_kgdb++;
472 kgdb_info[ks->cpu].exception_state |= exception_state;
474 if (exception_state == DCPU_WANT_MASTER)
475 atomic_inc(&masters_in_kgdb);
477 atomic_inc(&slaves_in_kgdb);
479 if (arch_kgdb_ops.disable_hw_break)
480 arch_kgdb_ops.disable_hw_break(regs);
484 * Interrupts will be restored by the 'trap return' code, except when
487 local_irq_save(flags);
490 kgdb_info[cpu].debuggerinfo = regs;
491 kgdb_info[cpu].task = current;
492 kgdb_info[cpu].ret_state = 0;
493 kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT;
495 /* Make sure the above info reaches the primary CPU */
498 if (exception_level == 1) {
499 if (raw_spin_trylock(&dbg_master_lock))
500 atomic_xchg(&kgdb_active, cpu);
501 goto cpu_master_loop;
505 * CPU will loop if it is a slave or request to become a kgdb
506 * master cpu and acquire the kgdb_active lock:
510 if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) {
511 kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER;
512 goto cpu_master_loop;
513 } else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
514 if (raw_spin_trylock(&dbg_master_lock)) {
515 atomic_xchg(&kgdb_active, cpu);
518 } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
519 if (!raw_spin_is_locked(&dbg_slave_lock))
523 /* Return to normal operation by executing any
524 * hw breakpoint fixup.
526 if (arch_kgdb_ops.correct_hw_break)
527 arch_kgdb_ops.correct_hw_break();
530 kgdb_info[cpu].exception_state &=
531 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
532 kgdb_info[cpu].enter_kgdb--;
533 smp_mb__before_atomic_dec();
534 atomic_dec(&slaves_in_kgdb);
535 dbg_touch_watchdogs();
536 local_irq_restore(flags);
543 * For single stepping, try to only enter on the processor
544 * that was single stepping. To guard against a deadlock, the
545 * kernel will only try for the value of sstep_tries before
546 * giving up and continuing on.
548 if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
549 (kgdb_info[cpu].task &&
550 kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
551 atomic_set(&kgdb_active, -1);
552 raw_spin_unlock(&dbg_master_lock);
553 dbg_touch_watchdogs();
554 local_irq_restore(flags);
559 if (!kgdb_io_ready(1)) {
560 kgdb_info[cpu].ret_state = 1;
561 goto kgdb_restore; /* No I/O connection, resume the system */
565 * Don't enter if we have hit a removed breakpoint.
567 if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
570 /* Call the I/O driver's pre_exception routine */
571 if (dbg_io_ops->pre_exception)
572 dbg_io_ops->pre_exception();
575 * Get the passive CPU lock which will hold all the non-primary
576 * CPU in a spin state while the debugger is active
578 if (!kgdb_single_step)
579 raw_spin_lock(&dbg_slave_lock);
582 /* Signal the other CPUs to enter kgdb_wait() */
583 if ((!kgdb_single_step) && kgdb_do_roundup)
584 kgdb_roundup_cpus(flags);
588 * Wait for the other CPUs to be notified and be waiting for us:
590 while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) +
591 atomic_read(&slaves_in_kgdb)) != online_cpus)
595 * At this point the primary processor is completely
596 * in the debugger and all secondary CPUs are quiescent
598 dbg_deactivate_sw_breakpoints();
599 kgdb_single_step = 0;
600 kgdb_contthread = current;
602 trace_on = tracing_is_on();
610 error = kdb_stub(ks);
615 error = gdb_serial_stub(ks);
618 if (error == DBG_PASS_EVENT) {
619 dbg_kdb_mode = !dbg_kdb_mode;
620 } else if (error == DBG_SWITCH_CPU_EVENT) {
621 kgdb_info[dbg_switch_cpu].exception_state |=
625 kgdb_info[cpu].ret_state = error;
630 /* Call the I/O driver's post_exception routine */
631 if (dbg_io_ops->post_exception)
632 dbg_io_ops->post_exception();
634 if (!kgdb_single_step) {
635 raw_spin_unlock(&dbg_slave_lock);
636 /* Wait till all the CPUs have quit from the debugger. */
637 while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb))
642 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
643 int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
644 if (kgdb_info[sstep_cpu].task)
645 kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
649 if (arch_kgdb_ops.correct_hw_break)
650 arch_kgdb_ops.correct_hw_break();
654 kgdb_info[cpu].exception_state &=
655 ~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
656 kgdb_info[cpu].enter_kgdb--;
657 smp_mb__before_atomic_dec();
658 atomic_dec(&masters_in_kgdb);
659 /* Free kgdb_active */
660 atomic_set(&kgdb_active, -1);
661 raw_spin_unlock(&dbg_master_lock);
662 dbg_touch_watchdogs();
663 local_irq_restore(flags);
665 return kgdb_info[cpu].ret_state;
669 * kgdb_handle_exception() - main entry point from a kernel exception
672 * interface locks, if any (begin_session)
673 * kgdb lock (kgdb_active)
676 kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
678 struct kgdb_state kgdb_var;
679 struct kgdb_state *ks = &kgdb_var;
681 ks->cpu = raw_smp_processor_id();
682 ks->ex_vector = evector;
684 ks->err_code = ecode;
685 ks->kgdb_usethreadid = 0;
686 ks->linux_regs = regs;
688 if (kgdb_reenter_check(ks))
689 return 0; /* Ouch, double exception ! */
690 if (kgdb_info[ks->cpu].enter_kgdb != 0)
693 return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
696 int kgdb_nmicallback(int cpu, void *regs)
699 struct kgdb_state kgdb_var;
700 struct kgdb_state *ks = &kgdb_var;
702 memset(ks, 0, sizeof(struct kgdb_state));
704 ks->linux_regs = regs;
706 if (kgdb_info[ks->cpu].enter_kgdb == 0 &&
707 raw_spin_is_locked(&dbg_master_lock)) {
708 kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE);
715 static void kgdb_console_write(struct console *co, const char *s,
720 /* If we're debugging, or KGDB has not connected, don't try
722 if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode)
725 local_irq_save(flags);
726 gdbstub_msg_write(s, count);
727 local_irq_restore(flags);
730 static struct console kgdbcons = {
732 .write = kgdb_console_write,
733 .flags = CON_PRINTBUFFER | CON_ENABLED,
737 #ifdef CONFIG_MAGIC_SYSRQ
738 static void sysrq_handle_dbg(int key)
741 printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
744 if (!kgdb_connected) {
745 #ifdef CONFIG_KGDB_KDB
747 printk(KERN_CRIT "KGDB or $3#33 for KDB\n");
749 printk(KERN_CRIT "Entering KGDB\n");
756 static struct sysrq_key_op sysrq_dbg_op = {
757 .handler = sysrq_handle_dbg,
758 .help_msg = "debug(G)",
759 .action_msg = "DEBUG",
763 static int kgdb_panic_event(struct notifier_block *self,
768 kdb_printf("PANIC: %s\n", (char *)data);
773 static struct notifier_block kgdb_panic_event_nb = {
774 .notifier_call = kgdb_panic_event,
778 void __weak kgdb_arch_late(void)
782 void __init dbg_late_init(void)
784 dbg_is_early = false;
785 if (kgdb_io_module_registered)
787 kdb_init(KDB_INIT_FULL);
791 dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x)
794 * Take the following action on reboot notify depending on value:
795 * 1 == Enter debugger
796 * 0 == [the default] detatch debug client
797 * -1 == Do nothing... and use this until the board resets
799 switch (kgdbreboot) {
811 static struct notifier_block dbg_reboot_notifier = {
812 .notifier_call = dbg_notify_reboot,
817 static void kgdb_register_callbacks(void)
819 if (!kgdb_io_module_registered) {
820 kgdb_io_module_registered = 1;
824 register_reboot_notifier(&dbg_reboot_notifier);
825 atomic_notifier_chain_register(&panic_notifier_list,
826 &kgdb_panic_event_nb);
827 #ifdef CONFIG_MAGIC_SYSRQ
828 register_sysrq_key('g', &sysrq_dbg_op);
830 if (kgdb_use_con && !kgdb_con_registered) {
831 register_console(&kgdbcons);
832 kgdb_con_registered = 1;
837 static void kgdb_unregister_callbacks(void)
840 * When this routine is called KGDB should unregister from the
841 * panic handler and clean up, making sure it is not handling any
842 * break exceptions at the time.
844 if (kgdb_io_module_registered) {
845 kgdb_io_module_registered = 0;
846 unregister_reboot_notifier(&dbg_reboot_notifier);
847 atomic_notifier_chain_unregister(&panic_notifier_list,
848 &kgdb_panic_event_nb);
850 #ifdef CONFIG_MAGIC_SYSRQ
851 unregister_sysrq_key('g', &sysrq_dbg_op);
853 if (kgdb_con_registered) {
854 unregister_console(&kgdbcons);
855 kgdb_con_registered = 0;
861 * There are times a tasklet needs to be used vs a compiled in
862 * break point so as to cause an exception outside a kgdb I/O module,
863 * such as is the case with kgdboe, where calling a breakpoint in the
864 * I/O driver itself would be fatal.
866 static void kgdb_tasklet_bpt(unsigned long ing)
869 atomic_set(&kgdb_break_tasklet_var, 0);
872 static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0);
874 void kgdb_schedule_breakpoint(void)
876 if (atomic_read(&kgdb_break_tasklet_var) ||
877 atomic_read(&kgdb_active) != -1 ||
878 atomic_read(&kgdb_setting_breakpoint))
880 atomic_inc(&kgdb_break_tasklet_var);
881 tasklet_schedule(&kgdb_tasklet_breakpoint);
883 EXPORT_SYMBOL_GPL(kgdb_schedule_breakpoint);
885 static void kgdb_initial_breakpoint(void)
889 printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
894 * kgdb_register_io_module - register KGDB IO module
895 * @new_dbg_io_ops: the io ops vector
897 * Register it with the KGDB core.
899 int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
903 spin_lock(&kgdb_registration_lock);
906 spin_unlock(&kgdb_registration_lock);
908 printk(KERN_ERR "kgdb: Another I/O driver is already "
909 "registered with KGDB.\n");
913 if (new_dbg_io_ops->init) {
914 err = new_dbg_io_ops->init();
916 spin_unlock(&kgdb_registration_lock);
921 dbg_io_ops = new_dbg_io_ops;
923 spin_unlock(&kgdb_registration_lock);
925 printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
926 new_dbg_io_ops->name);
929 kgdb_register_callbacks();
932 kgdb_initial_breakpoint();
936 EXPORT_SYMBOL_GPL(kgdb_register_io_module);
939 * kkgdb_unregister_io_module - unregister KGDB IO module
940 * @old_dbg_io_ops: the io ops vector
942 * Unregister it with the KGDB core.
944 void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops)
946 BUG_ON(kgdb_connected);
949 * KGDB is no longer able to communicate out, so
950 * unregister our callbacks and reset state.
952 kgdb_unregister_callbacks();
954 spin_lock(&kgdb_registration_lock);
956 WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops);
959 spin_unlock(&kgdb_registration_lock);
962 "kgdb: Unregistered I/O driver %s, debugger disabled.\n",
963 old_dbg_io_ops->name);
965 EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
967 int dbg_io_get_char(void)
969 int ret = dbg_io_ops->read_char();
970 if (ret == NO_POLL_CHAR)
980 * kgdb_breakpoint - generate breakpoint exception
982 * This function will generate a breakpoint exception. It is used at the
983 * beginning of a program to sync up with a debugger and can be used
984 * otherwise as a quick means to stop program execution and "break" into
987 void kgdb_breakpoint(void)
989 atomic_inc(&kgdb_setting_breakpoint);
990 wmb(); /* Sync point before breakpoint */
991 arch_kgdb_breakpoint();
992 wmb(); /* Sync point after breakpoint */
993 atomic_dec(&kgdb_setting_breakpoint);
995 EXPORT_SYMBOL_GPL(kgdb_breakpoint);
997 static int __init opt_kgdb_wait(char *str)
1001 kdb_init(KDB_INIT_EARLY);
1002 if (kgdb_io_module_registered)
1003 kgdb_initial_breakpoint();
1008 early_param("kgdbwait", opt_kgdb_wait);