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Root/kernel/kgdb.c

1	/*
2	* KGDB stub.
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@suse.cz>
10	* Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
11	* Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
12	* Copyright (C) 2005-2008 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/reboot.h>
41	#include <linux/string.h>
42	#include <linux/delay.h>
43	#include <linux/sched.h>
44	#include <linux/sysrq.h>
45	#include <linux/init.h>
46	#include <linux/kgdb.h>
47	#include <linux/pid.h>
48	#include <linux/smp.h>
49	#include <linux/mm.h>
50
51	#include <asm/cacheflush.h>
52	#include <asm/byteorder.h>
53	#include <asm/atomic.h>
54	#include <asm/system.h>
55	#include <asm/unaligned.h>
56
57	static int kgdb_break_asap;
58
59	#define KGDB_MAX_THREAD_QUERY 17
60	struct kgdb_state {
61	int ex_vector;
62	int signo;
63	int err_code;
64	int cpu;
65	int pass_exception;
66	unsigned long thr_query;
67	unsigned long threadid;
68	long kgdb_usethreadid;
69	struct pt_regs *linux_regs;
70	};
71
72	static struct debuggerinfo_struct {
73	void *debuggerinfo;
74	struct task_struct *task;
75	} kgdb_info[NR_CPUS];
76
77	/**
78	* kgdb_connected - Is a host GDB connected to us?
79	*/
80	int kgdb_connected;
81	EXPORT_SYMBOL_GPL(kgdb_connected);
82
83	/* All the KGDB handlers are installed */
84	static int kgdb_io_module_registered;
85
86	/* Guard for recursive entry */
87	static int exception_level;
88
89	static struct kgdb_io *kgdb_io_ops;
90	static DEFINE_SPINLOCK(kgdb_registration_lock);
91
92	/* kgdb console driver is loaded */
93	static int kgdb_con_registered;
94	/* determine if kgdb console output should be used */
95	static int kgdb_use_con;
96
97	static int __init opt_kgdb_con(char *str)
98	{
99	kgdb_use_con = 1;
100	return 0;
101	}
102
103	early_param("kgdbcon", opt_kgdb_con);
104
105	module_param(kgdb_use_con, int, 0644);
106
107	/*
108	* Holds information about breakpoints in a kernel. These breakpoints are
109	* added and removed by gdb.
110	*/
111	static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = {
112	[0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED }
113	};
114
115	/*
116	* The CPU# of the active CPU, or -1 if none:
117	*/
118	atomic_t kgdb_active = ATOMIC_INIT(-1);
119
120	/*
121	* We use NR_CPUs not PERCPU, in case kgdb is used to debug early
122	* bootup code (which might not have percpu set up yet):
123	*/
124	static atomic_t passive_cpu_wait[NR_CPUS];
125	static atomic_t cpu_in_kgdb[NR_CPUS];
126	atomic_t kgdb_setting_breakpoint;
127
128	struct task_struct *kgdb_usethread;
129	struct task_struct *kgdb_contthread;
130
131	int kgdb_single_step;
132
133	/* Our I/O buffers. */
134	static char remcom_in_buffer[BUFMAX];
135	static char remcom_out_buffer[BUFMAX];
136
137	/* Storage for the registers, in GDB format. */
138	static unsigned long gdb_regs[(NUMREGBYTES +
139	sizeof(unsigned long) - 1) /
140	sizeof(unsigned long)];
141
142	/* to keep track of the CPU which is doing the single stepping*/
143	atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1);
144
145	/*
146	* If you are debugging a problem where roundup (the collection of
147	* all other CPUs) is a problem [this should be extremely rare],
148	* then use the nokgdbroundup option to avoid roundup. In that case
149	* the other CPUs might interfere with your debugging context, so
150	* use this with care:
151	*/
152	static int kgdb_do_roundup = 1;
153
154	static int __init opt_nokgdbroundup(char *str)
155	{
156	kgdb_do_roundup = 0;
157
158	return 0;
159	}
160
161	early_param("nokgdbroundup", opt_nokgdbroundup);
162
163	/*
164	* Finally, some KGDB code :-)
165	*/
166
167	/*
168	* Weak aliases for breakpoint management,
169	* can be overriden by architectures when needed:
170	*/
171	int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
172	{
173	int err;
174
175	err = probe_kernel_read(saved_instr, (char *)addr, BREAK_INSTR_SIZE);
176	if (err)
177	return err;
178
179	return probe_kernel_write((char *)addr, arch_kgdb_ops.gdb_bpt_instr,
180	BREAK_INSTR_SIZE);
181	}
182
183	int __weak kgdb_arch_remove_breakpoint(unsigned long addr, char *bundle)
184	{
185	return probe_kernel_write((char *)addr,
186	(char *)bundle, BREAK_INSTR_SIZE);
187	}
188
189	int __weak kgdb_validate_break_address(unsigned long addr)
190	{
191	char tmp_variable[BREAK_INSTR_SIZE];
192	int err;
193	/* Validate setting the breakpoint and then removing it. In the
194	* remove fails, the kernel needs to emit a bad message because we
195	* are deep trouble not being able to put things back the way we
196	* found them.
197	*/
198	err = kgdb_arch_set_breakpoint(addr, tmp_variable);
199	if (err)
200	return err;
201	err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
202	if (err)
203	printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
204	"memory destroyed at: %lx", addr);
205	return err;
206	}
207
208	unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
209	{
210	return instruction_pointer(regs);
211	}
212
213	int __weak kgdb_arch_init(void)
214	{
215	return 0;
216	}
217
218	int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
219	{
220	return 0;
221	}
222
223	void __weak
224	kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
225	{
226	return;
227	}
228
229	/**
230	* kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
231	* @regs: Current &struct pt_regs.
232	*
233	* This function will be called if the particular architecture must
234	* disable hardware debugging while it is processing gdb packets or
235	* handling exception.
236	*/
237	void __weak kgdb_disable_hw_debug(struct pt_regs *regs)
238	{
239	}
240
241	/*
242	* GDB remote protocol parser:
243	*/
244
245	static int hex(char ch)
246	{
247	if ((ch >= 'a') && (ch <= 'f'))
248	return ch - 'a' + 10;
249	if ((ch >= '0') && (ch <= '9'))
250	return ch - '0';
251	if ((ch >= 'A') && (ch <= 'F'))
252	return ch - 'A' + 10;
253	return -1;
254	}
255
256	/* scan for the sequence $<data>#<checksum> */
257	static void get_packet(char *buffer)
258	{
259	unsigned char checksum;
260	unsigned char xmitcsum;
261	int count;
262	char ch;
263
264	do {
265	/*
266	* Spin and wait around for the start character, ignore all
267	* other characters:
268	*/
269	while ((ch = (kgdb_io_ops->read_char())) != '$')
270	/* nothing */;
271
272	kgdb_connected = 1;
273	checksum = 0;
274	xmitcsum = -1;
275
276	count = 0;
277
278	/*
279	* now, read until a # or end of buffer is found:
280	*/
281	while (count < (BUFMAX - 1)) {
282	ch = kgdb_io_ops->read_char();
283	if (ch == '#')
284	break;
285	checksum = checksum + ch;
286	buffer[count] = ch;
287	count = count + 1;
288	}
289	buffer[count] = 0;
290
291	if (ch == '#') {
292	xmitcsum = hex(kgdb_io_ops->read_char()) << 4;
293	xmitcsum += hex(kgdb_io_ops->read_char());
294
295	if (checksum != xmitcsum)
296	/* failed checksum */
297	kgdb_io_ops->write_char('-');
298	else
299	/* successful transfer */
300	kgdb_io_ops->write_char('+');
301	if (kgdb_io_ops->flush)
302	kgdb_io_ops->flush();
303	}
304	} while (checksum != xmitcsum);
305	}
306
307	/*
308	* Send the packet in buffer.
309	* Check for gdb connection if asked for.
310	*/
311	static void put_packet(char *buffer)
312	{
313	unsigned char checksum;
314	int count;
315	char ch;
316
317	/*
318	* $<packet info>#<checksum>.
319	*/
320	while (1) {
321	kgdb_io_ops->write_char('$');
322	checksum = 0;
323	count = 0;
324
325	while ((ch = buffer[count])) {
326	kgdb_io_ops->write_char(ch);
327	checksum += ch;
328	count++;
329	}
330
331	kgdb_io_ops->write_char('#');
332	kgdb_io_ops->write_char(hex_asc_hi(checksum));
333	kgdb_io_ops->write_char(hex_asc_lo(checksum));
334	if (kgdb_io_ops->flush)
335	kgdb_io_ops->flush();
336
337	/* Now see what we get in reply. */
338	ch = kgdb_io_ops->read_char();
339
340	if (ch == 3)
341	ch = kgdb_io_ops->read_char();
342
343	/* If we get an ACK, we are done. */
344	if (ch == '+')
345	return;
346
347	/*
348	* If we get the start of another packet, this means
349	* that GDB is attempting to reconnect. We will NAK
350	* the packet being sent, and stop trying to send this
351	* packet.
352	*/
353	if (ch == '$') {
354	kgdb_io_ops->write_char('-');
355	if (kgdb_io_ops->flush)
356	kgdb_io_ops->flush();
357	return;
358	}
359	}
360	}
361
362	/*
363	* Convert the memory pointed to by mem into hex, placing result in buf.
364	* Return a pointer to the last char put in buf (null). May return an error.
365	*/
366	int kgdb_mem2hex(char mem, char buf, int count)
367	{
368	char *tmp;
369	int err;
370
371	/*
372	* We use the upper half of buf as an intermediate buffer for the
373	* raw memory copy. Hex conversion will work against this one.
374	*/
375	tmp = buf + count;
376
377	err = probe_kernel_read(tmp, mem, count);
378	if (!err) {
379	while (count > 0) {
380	buf = pack_hex_byte(buf, *tmp);
381	tmp++;
382	count--;
383	}
384
385	*buf = 0;
386	}
387
388	return err;
389	}
390
391	/*
392	* Copy the binary array pointed to by buf into mem. Fix $, #, and
393	* 0x7d escaped with 0x7d. Return a pointer to the character after
394	* the last byte written.
395	*/
396	static int kgdb_ebin2mem(char buf, char mem, int count)
397	{
398	int err = 0;
399	char c;
400
401	while (count-- > 0) {
402	c = *buf++;
403	if (c == 0x7d)
404	c = *buf++ ^ 0x20;
405
406	err = probe_kernel_write(mem, &c, 1);
407	if (err)
408	break;
409
410	mem++;
411	}
412
413	return err;
414	}
415
416	/*
417	* Convert the hex array pointed to by buf into binary to be placed in mem.
418	* Return a pointer to the character AFTER the last byte written.
419	* May return an error.
420	*/
421	int kgdb_hex2mem(char buf, char mem, int count)
422	{
423	char *tmp_raw;
424	char *tmp_hex;
425
426	/*
427	* We use the upper half of buf as an intermediate buffer for the
428	* raw memory that is converted from hex.
429	*/
430	tmp_raw = buf + count * 2;
431
432	tmp_hex = tmp_raw - 1;
433	while (tmp_hex >= buf) {
434	tmp_raw--;
435	tmp_raw = hex(tmp_hex--);
436	tmp_raw \|= hex(tmp_hex--) << 4;
437	}
438
439	return probe_kernel_write(mem, tmp_raw, count);
440	}
441
442	/*
443	* While we find nice hex chars, build a long_val.
444	* Return number of chars processed.
445	*/
446	int kgdb_hex2long(char *ptr, unsigned long long_val)
447	{
448	int hex_val;
449	int num = 0;
450	int negate = 0;
451
452	*long_val = 0;
453
454	if (**ptr == '-') {
455	negate = 1;
456	(*ptr)++;
457	}
458	while (**ptr) {
459	hex_val = hex(**ptr);
460	if (hex_val < 0)
461	break;
462
463	long_val = (long_val << 4) \| hex_val;
464	num++;
465	(*ptr)++;
466	}
467
468	if (negate)
469	long_val = -long_val;
470
471	return num;
472	}
473
474	/* Write memory due to an 'M' or 'X' packet. */
475	static int write_mem_msg(int binary)
476	{
477	char *ptr = &remcom_in_buffer[1];
478	unsigned long addr;
479	unsigned long length;
480	int err;
481
482	if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
483	kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
484	if (binary)
485	err = kgdb_ebin2mem(ptr, (char *)addr, length);
486	else
487	err = kgdb_hex2mem(ptr, (char *)addr, length);
488	if (err)
489	return err;
490	if (CACHE_FLUSH_IS_SAFE)
491	flush_icache_range(addr, addr + length);
492	return 0;
493	}
494
495	return -EINVAL;
496	}
497
498	static void error_packet(char *pkt, int error)
499	{
500	error = -error;
501	pkt[0] = 'E';
502	pkt[1] = hex_asc[(error / 10)];
503	pkt[2] = hex_asc[(error % 10)];
504	pkt[3] = '\0';
505	}
506
507	/*
508	* Thread ID accessors. We represent a flat TID space to GDB, where
509	* the per CPU idle threads (which under Linux all have PID 0) are
510	* remapped to negative TIDs.
511	*/
512
513	#define BUF_THREAD_ID_SIZE 16
514
515	static char pack_threadid(char pkt, unsigned char *id)
516	{
517	char *limit;
518
519	limit = pkt + BUF_THREAD_ID_SIZE;
520	while (pkt < limit)
521	pkt = pack_hex_byte(pkt, *id++);
522
523	return pkt;
524	}
525
526	static void int_to_threadref(unsigned char *id, int value)
527	{
528	unsigned char *scan;
529	int i = 4;
530
531	scan = (unsigned char *)id;
532	while (i--)
533	*scan++ = 0;
534	put_unaligned_be32(value, scan);
535	}
536
537	static struct task_struct getthread(struct pt_regs regs, int tid)
538	{
539	/*
540	* Non-positive TIDs are remapped to the cpu shadow information
541	*/
542	if (tid == 0 \|\| tid == -1)
543	tid = -atomic_read(&kgdb_active) - 2;
544	if (tid < 0) {
545	if (kgdb_info[-tid - 2].task)
546	return kgdb_info[-tid - 2].task;
547	else
548	return idle_task(-tid - 2);
549	}
550
551	/*
552	* find_task_by_pid_ns() does not take the tasklist lock anymore
553	* but is nicely RCU locked - hence is a pretty resilient
554	* thing to use:
555	*/
556	return find_task_by_pid_ns(tid, &init_pid_ns);
557	}
558
559	/*
560	* CPU debug state control:
561	*/
562
563	#ifdef CONFIG_SMP
564	static void kgdb_wait(struct pt_regs *regs)
565	{
566	unsigned long flags;
567	int cpu;
568
569	local_irq_save(flags);
570	cpu = raw_smp_processor_id();
571	kgdb_info[cpu].debuggerinfo = regs;
572	kgdb_info[cpu].task = current;
573	/*
574	* Make sure the above info reaches the primary CPU before
575	* our cpu_in_kgdb[] flag setting does:
576	*/
577	smp_wmb();
578	atomic_set(&cpu_in_kgdb[cpu], 1);
579
580	/* Wait till primary CPU is done with debugging */
581	while (atomic_read(&passive_cpu_wait[cpu]))
582	cpu_relax();
583
584	kgdb_info[cpu].debuggerinfo = NULL;
585	kgdb_info[cpu].task = NULL;
586
587	/* fix up hardware debug registers on local cpu */
588	if (arch_kgdb_ops.correct_hw_break)
589	arch_kgdb_ops.correct_hw_break();
590
591	/* Signal the primary CPU that we are done: */
592	atomic_set(&cpu_in_kgdb[cpu], 0);
593	touch_softlockup_watchdog();
594	clocksource_touch_watchdog();
595	local_irq_restore(flags);
596	}
597	#endif
598
599	/*
600	* Some architectures need cache flushes when we set/clear a
601	* breakpoint:
602	*/
603	static void kgdb_flush_swbreak_addr(unsigned long addr)
604	{
605	if (!CACHE_FLUSH_IS_SAFE)
606	return;
607
608	if (current->mm && current->mm->mmap_cache) {
609	flush_cache_range(current->mm->mmap_cache,
610	addr, addr + BREAK_INSTR_SIZE);
611	}
612	/* Force flush instruction cache if it was outside the mm */
613	flush_icache_range(addr, addr + BREAK_INSTR_SIZE);
614	}
615
616	/*
617	* SW breakpoint management:
618	*/
619	static int kgdb_activate_sw_breakpoints(void)
620	{
621	unsigned long addr;
622	int error = 0;
623	int i;
624
625	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
626	if (kgdb_break[i].state != BP_SET)
627	continue;
628
629	addr = kgdb_break[i].bpt_addr;
630	error = kgdb_arch_set_breakpoint(addr,
631	kgdb_break[i].saved_instr);
632	if (error)
633	return error;
634
635	kgdb_flush_swbreak_addr(addr);
636	kgdb_break[i].state = BP_ACTIVE;
637	}
638	return 0;
639	}
640
641	static int kgdb_set_sw_break(unsigned long addr)
642	{
643	int err = kgdb_validate_break_address(addr);
644	int breakno = -1;
645	int i;
646
647	if (err)
648	return err;
649
650	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
651	if ((kgdb_break[i].state == BP_SET) &&
652	(kgdb_break[i].bpt_addr == addr))
653	return -EEXIST;
654	}
655	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
656	if (kgdb_break[i].state == BP_REMOVED &&
657	kgdb_break[i].bpt_addr == addr) {
658	breakno = i;
659	break;
660	}
661	}
662
663	if (breakno == -1) {
664	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
665	if (kgdb_break[i].state == BP_UNDEFINED) {
666	breakno = i;
667	break;
668	}
669	}
670	}
671
672	if (breakno == -1)
673	return -E2BIG;
674
675	kgdb_break[breakno].state = BP_SET;
676	kgdb_break[breakno].type = BP_BREAKPOINT;
677	kgdb_break[breakno].bpt_addr = addr;
678
679	return 0;
680	}
681
682	static int kgdb_deactivate_sw_breakpoints(void)
683	{
684	unsigned long addr;
685	int error = 0;
686	int i;
687
688	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
689	if (kgdb_break[i].state != BP_ACTIVE)
690	continue;
691	addr = kgdb_break[i].bpt_addr;
692	error = kgdb_arch_remove_breakpoint(addr,
693	kgdb_break[i].saved_instr);
694	if (error)
695	return error;
696
697	kgdb_flush_swbreak_addr(addr);
698	kgdb_break[i].state = BP_SET;
699	}
700	return 0;
701	}
702
703	static int kgdb_remove_sw_break(unsigned long addr)
704	{
705	int i;
706
707	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
708	if ((kgdb_break[i].state == BP_SET) &&
709	(kgdb_break[i].bpt_addr == addr)) {
710	kgdb_break[i].state = BP_REMOVED;
711	return 0;
712	}
713	}
714	return -ENOENT;
715	}
716
717	int kgdb_isremovedbreak(unsigned long addr)
718	{
719	int i;
720
721	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
722	if ((kgdb_break[i].state == BP_REMOVED) &&
723	(kgdb_break[i].bpt_addr == addr))
724	return 1;
725	}
726	return 0;
727	}
728
729	static int remove_all_break(void)
730	{
731	unsigned long addr;
732	int error;
733	int i;
734
735	/* Clear memory breakpoints. */
736	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
737	if (kgdb_break[i].state != BP_ACTIVE)
738	goto setundefined;
739	addr = kgdb_break[i].bpt_addr;
740	error = kgdb_arch_remove_breakpoint(addr,
741	kgdb_break[i].saved_instr);
742	if (error)
743	printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
744	addr);
745	setundefined:
746	kgdb_break[i].state = BP_UNDEFINED;
747	}
748
749	/* Clear hardware breakpoints. */
750	if (arch_kgdb_ops.remove_all_hw_break)
751	arch_kgdb_ops.remove_all_hw_break();
752
753	return 0;
754	}
755
756	/*
757	* Remap normal tasks to their real PID,
758	* CPU shadow threads are mapped to -CPU - 2
759	*/
760	static inline int shadow_pid(int realpid)
761	{
762	if (realpid)
763	return realpid;
764
765	return -raw_smp_processor_id() - 2;
766	}
767
768	static char gdbmsgbuf[BUFMAX + 1];
769
770	static void kgdb_msg_write(const char *s, int len)
771	{
772	char *bufptr;
773	int wcount;
774	int i;
775
776	/* 'O'utput */
777	gdbmsgbuf[0] = 'O';
778
779	/* Fill and send buffers... */
780	while (len > 0) {
781	bufptr = gdbmsgbuf + 1;
782
783	/* Calculate how many this time */
784	if ((len << 1) > (BUFMAX - 2))
785	wcount = (BUFMAX - 2) >> 1;
786	else
787	wcount = len;
788
789	/* Pack in hex chars */
790	for (i = 0; i < wcount; i++)
791	bufptr = pack_hex_byte(bufptr, s[i]);
792	*bufptr = '\0';
793
794	/* Move up */
795	s += wcount;
796	len -= wcount;
797
798	/* Write packet */
799	put_packet(gdbmsgbuf);
800	}
801	}
802
803	/*
804	* Return true if there is a valid kgdb I/O module. Also if no
805	* debugger is attached a message can be printed to the console about
806	* waiting for the debugger to attach.
807	*
808	* The print_wait argument is only to be true when called from inside
809	* the core kgdb_handle_exception, because it will wait for the
810	* debugger to attach.
811	*/
812	static int kgdb_io_ready(int print_wait)
813	{
814	if (!kgdb_io_ops)
815	return 0;
816	if (kgdb_connected)
817	return 1;
818	if (atomic_read(&kgdb_setting_breakpoint))
819	return 1;
820	if (print_wait)
821	printk(KERN_CRIT "KGDB: Waiting for remote debugger\n");
822	return 1;
823	}
824
825	/*
826	* All the functions that start with gdb_cmd are the various
827	* operations to implement the handlers for the gdbserial protocol
828	* where KGDB is communicating with an external debugger
829	*/
830
831	/* Handle the '?' status packets */
832	static void gdb_cmd_status(struct kgdb_state *ks)
833	{
834	/*
835	* We know that this packet is only sent
836	* during initial connect. So to be safe,
837	* we clear out our breakpoints now in case
838	* GDB is reconnecting.
839	*/
840	remove_all_break();
841
842	remcom_out_buffer[0] = 'S';
843	pack_hex_byte(&remcom_out_buffer[1], ks->signo);
844	}
845
846	/* Handle the 'g' get registers request */
847	static void gdb_cmd_getregs(struct kgdb_state *ks)
848	{
849	struct task_struct *thread;
850	void *local_debuggerinfo;
851	int i;
852
853	thread = kgdb_usethread;
854	if (!thread) {
855	thread = kgdb_info[ks->cpu].task;
856	local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
857	} else {
858	local_debuggerinfo = NULL;
859	for_each_online_cpu(i) {
860	/*
861	* Try to find the task on some other
862	* or possibly this node if we do not
863	* find the matching task then we try
864	* to approximate the results.
865	*/
866	if (thread == kgdb_info[i].task)
867	local_debuggerinfo = kgdb_info[i].debuggerinfo;
868	}
869	}
870
871	/*
872	* All threads that don't have debuggerinfo should be
873	* in __schedule() sleeping, since all other CPUs
874	* are in kgdb_wait, and thus have debuggerinfo.
875	*/
876	if (local_debuggerinfo) {
877	pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
878	} else {
879	/*
880	* Pull stuff saved during switch_to; nothing
881	* else is accessible (or even particularly
882	* relevant).
883	*
884	* This should be enough for a stack trace.
885	*/
886	sleeping_thread_to_gdb_regs(gdb_regs, thread);
887	}
888	kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
889	}
890
891	/* Handle the 'G' set registers request */
892	static void gdb_cmd_setregs(struct kgdb_state *ks)
893	{
894	kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
895
896	if (kgdb_usethread && kgdb_usethread != current) {
897	error_packet(remcom_out_buffer, -EINVAL);
898	} else {
899	gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
900	strcpy(remcom_out_buffer, "OK");
901	}
902	}
903
904	/* Handle the 'm' memory read bytes */
905	static void gdb_cmd_memread(struct kgdb_state *ks)
906	{
907	char *ptr = &remcom_in_buffer[1];
908	unsigned long length;
909	unsigned long addr;
910	int err;
911
912	if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
913	kgdb_hex2long(&ptr, &length) > 0) {
914	err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
915	if (err)
916	error_packet(remcom_out_buffer, err);
917	} else {
918	error_packet(remcom_out_buffer, -EINVAL);
919	}
920	}
921
922	/* Handle the 'M' memory write bytes */
923	static void gdb_cmd_memwrite(struct kgdb_state *ks)
924	{
925	int err = write_mem_msg(0);
926
927	if (err)
928	error_packet(remcom_out_buffer, err);
929	else
930	strcpy(remcom_out_buffer, "OK");
931	}
932
933	/* Handle the 'X' memory binary write bytes */
934	static void gdb_cmd_binwrite(struct kgdb_state *ks)
935	{
936	int err = write_mem_msg(1);
937
938	if (err)
939	error_packet(remcom_out_buffer, err);
940	else
941	strcpy(remcom_out_buffer, "OK");
942	}
943
944	/* Handle the 'D' or 'k', detach or kill packets */
945	static void gdb_cmd_detachkill(struct kgdb_state *ks)
946	{
947	int error;
948
949	/* The detach case */
950	if (remcom_in_buffer[0] == 'D') {
951	error = remove_all_break();
952	if (error < 0) {
953	error_packet(remcom_out_buffer, error);
954	} else {
955	strcpy(remcom_out_buffer, "OK");
956	kgdb_connected = 0;
957	}
958	put_packet(remcom_out_buffer);
959	} else {
960	/*
961	* Assume the kill case, with no exit code checking,
962	* trying to force detach the debugger:
963	*/
964	remove_all_break();
965	kgdb_connected = 0;
966	}
967	}
968
969	/* Handle the 'R' reboot packets */
970	static int gdb_cmd_reboot(struct kgdb_state *ks)
971	{
972	/* For now, only honor R0 */
973	if (strcmp(remcom_in_buffer, "R0") == 0) {
974	printk(KERN_CRIT "Executing emergency reboot\n");
975	strcpy(remcom_out_buffer, "OK");
976	put_packet(remcom_out_buffer);
977
978	/*
979	* Execution should not return from
980	* machine_emergency_restart()
981	*/
982	machine_emergency_restart();
983	kgdb_connected = 0;
984
985	return 1;
986	}
987	return 0;
988	}
989
990	/* Handle the 'q' query packets */
991	static void gdb_cmd_query(struct kgdb_state *ks)
992	{
993	struct task_struct *g;
994	struct task_struct *p;
995	unsigned char thref[8];
996	char *ptr;
997	int i;
998	int cpu;
999	int finished = 0;
1000
1001	switch (remcom_in_buffer[1]) {
1002	case 's':
1003	case 'f':
1004	if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10)) {
1005	error_packet(remcom_out_buffer, -EINVAL);
1006	break;
1007	}
1008
1009	i = 0;
1010	remcom_out_buffer[0] = 'm';
1011	ptr = remcom_out_buffer + 1;
1012	if (remcom_in_buffer[1] == 'f') {
1013	/* Each cpu is a shadow thread */
1014	for_each_online_cpu(cpu) {
1015	ks->thr_query = 0;
1016	int_to_threadref(thref, -cpu - 2);
1017	pack_threadid(ptr, thref);
1018	ptr += BUF_THREAD_ID_SIZE;
1019	*(ptr++) = ',';
1020	i++;
1021	}
1022	}
1023
1024	do_each_thread(g, p) {
1025	if (i >= ks->thr_query && !finished) {
1026	int_to_threadref(thref, p->pid);
1027	pack_threadid(ptr, thref);
1028	ptr += BUF_THREAD_ID_SIZE;
1029	*(ptr++) = ',';
1030	ks->thr_query++;
1031	if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
1032	finished = 1;
1033	}
1034	i++;
1035	} while_each_thread(g, p);
1036
1037	*(--ptr) = '\0';
1038	break;
1039
1040	case 'C':
1041	/* Current thread id */
1042	strcpy(remcom_out_buffer, "QC");
1043	ks->threadid = shadow_pid(current->pid);
1044	int_to_threadref(thref, ks->threadid);
1045	pack_threadid(remcom_out_buffer + 2, thref);
1046	break;
1047	case 'T':
1048	if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16)) {
1049	error_packet(remcom_out_buffer, -EINVAL);
1050	break;
1051	}
1052	ks->threadid = 0;
1053	ptr = remcom_in_buffer + 17;
1054	kgdb_hex2long(&ptr, &ks->threadid);
1055	if (!getthread(ks->linux_regs, ks->threadid)) {
1056	error_packet(remcom_out_buffer, -EINVAL);
1057	break;
1058	}
1059	if ((int)ks->threadid > 0) {
1060	kgdb_mem2hex(getthread(ks->linux_regs,
1061	ks->threadid)->comm,
1062	remcom_out_buffer, 16);
1063	} else {
1064	static char tmpstr[23 + BUF_THREAD_ID_SIZE];
1065
1066	sprintf(tmpstr, "shadowCPU%d",
1067	(int)(-ks->threadid - 2));
1068	kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
1069	}
1070	break;
1071	}
1072	}
1073
1074	/* Handle the 'H' task query packets */
1075	static void gdb_cmd_task(struct kgdb_state *ks)
1076	{
1077	struct task_struct *thread;
1078	char *ptr;
1079
1080	switch (remcom_in_buffer[1]) {
1081	case 'g':
1082	ptr = &remcom_in_buffer[2];
1083	kgdb_hex2long(&ptr, &ks->threadid);
1084	thread = getthread(ks->linux_regs, ks->threadid);
1085	if (!thread && ks->threadid > 0) {
1086	error_packet(remcom_out_buffer, -EINVAL);
1087	break;
1088	}
1089	kgdb_usethread = thread;
1090	ks->kgdb_usethreadid = ks->threadid;
1091	strcpy(remcom_out_buffer, "OK");
1092	break;
1093	case 'c':
1094	ptr = &remcom_in_buffer[2];
1095	kgdb_hex2long(&ptr, &ks->threadid);
1096	if (!ks->threadid) {
1097	kgdb_contthread = NULL;
1098	} else {
1099	thread = getthread(ks->linux_regs, ks->threadid);
1100	if (!thread && ks->threadid > 0) {
1101	error_packet(remcom_out_buffer, -EINVAL);
1102	break;
1103	}
1104	kgdb_contthread = thread;
1105	}
1106	strcpy(remcom_out_buffer, "OK");
1107	break;
1108	}
1109	}
1110
1111	/* Handle the 'T' thread query packets */
1112	static void gdb_cmd_thread(struct kgdb_state *ks)
1113	{
1114	char *ptr = &remcom_in_buffer[1];
1115	struct task_struct *thread;
1116
1117	kgdb_hex2long(&ptr, &ks->threadid);
1118	thread = getthread(ks->linux_regs, ks->threadid);
1119	if (thread)
1120	strcpy(remcom_out_buffer, "OK");
1121	else
1122	error_packet(remcom_out_buffer, -EINVAL);
1123	}
1124
1125	/* Handle the 'z' or 'Z' breakpoint remove or set packets */
1126	static void gdb_cmd_break(struct kgdb_state *ks)
1127	{
1128	/*
1129	* Since GDB-5.3, it's been drafted that '0' is a software
1130	* breakpoint, '1' is a hardware breakpoint, so let's do that.
1131	*/
1132	char *bpt_type = &remcom_in_buffer[1];
1133	char *ptr = &remcom_in_buffer[2];
1134	unsigned long addr;
1135	unsigned long length;
1136	int error = 0;
1137
1138	if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
1139	/* Unsupported */
1140	if (*bpt_type > '4')
1141	return;
1142	} else {
1143	if (bpt_type != '0' && bpt_type != '1')
1144	/* Unsupported. */
1145	return;
1146	}
1147
1148	/*
1149	* Test if this is a hardware breakpoint, and
1150	* if we support it:
1151	*/
1152	if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
1153	/* Unsupported. */
1154	return;
1155
1156	if (*(ptr++) != ',') {
1157	error_packet(remcom_out_buffer, -EINVAL);
1158	return;
1159	}
1160	if (!kgdb_hex2long(&ptr, &addr)) {
1161	error_packet(remcom_out_buffer, -EINVAL);
1162	return;
1163	}
1164	if (*(ptr++) != ',' \|\|
1165	!kgdb_hex2long(&ptr, &length)) {
1166	error_packet(remcom_out_buffer, -EINVAL);
1167	return;
1168	}
1169
1170	if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
1171	error = kgdb_set_sw_break(addr);
1172	else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
1173	error = kgdb_remove_sw_break(addr);
1174	else if (remcom_in_buffer[0] == 'Z')
1175	error = arch_kgdb_ops.set_hw_breakpoint(addr,
1176	(int)length, *bpt_type - '0');
1177	else if (remcom_in_buffer[0] == 'z')
1178	error = arch_kgdb_ops.remove_hw_breakpoint(addr,
1179	(int) length, *bpt_type - '0');
1180
1181	if (error == 0)
1182	strcpy(remcom_out_buffer, "OK");
1183	else
1184	error_packet(remcom_out_buffer, error);
1185	}
1186
1187	/* Handle the 'C' signal / exception passing packets */
1188	static int gdb_cmd_exception_pass(struct kgdb_state *ks)
1189	{
1190	/* C09 == pass exception
1191	* C15 == detach kgdb, pass exception
1192	*/
1193	if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
1194
1195	ks->pass_exception = 1;
1196	remcom_in_buffer[0] = 'c';
1197
1198	} else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
1199
1200	ks->pass_exception = 1;
1201	remcom_in_buffer[0] = 'D';
1202	remove_all_break();
1203	kgdb_connected = 0;
1204	return 1;
1205
1206	} else {
1207	error_packet(remcom_out_buffer, -EINVAL);
1208	return 0;
1209	}
1210
1211	/* Indicate fall through */
1212	return -1;
1213	}
1214
1215	/*
1216	* This function performs all gdbserial command procesing
1217	*/
1218	static int gdb_serial_stub(struct kgdb_state *ks)
1219	{
1220	int error = 0;
1221	int tmp;
1222
1223	/* Clear the out buffer. */
1224	memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1225
1226	if (kgdb_connected) {
1227	unsigned char thref[8];
1228	char *ptr;
1229
1230	/* Reply to host that an exception has occurred */
1231	ptr = remcom_out_buffer;
1232	*ptr++ = 'T';
1233	ptr = pack_hex_byte(ptr, ks->signo);
1234	ptr += strlen(strcpy(ptr, "thread:"));
1235	int_to_threadref(thref, shadow_pid(current->pid));
1236	ptr = pack_threadid(ptr, thref);
1237	*ptr++ = ';';
1238	put_packet(remcom_out_buffer);
1239	}
1240
1241	kgdb_usethread = kgdb_info[ks->cpu].task;
1242	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
1243	ks->pass_exception = 0;
1244
1245	while (1) {
1246	error = 0;
1247
1248	/* Clear the out buffer. */
1249	memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
1250
1251	get_packet(remcom_in_buffer);
1252
1253	switch (remcom_in_buffer[0]) {
1254	case '?': /* gdbserial status */
1255	gdb_cmd_status(ks);
1256	break;
1257	case 'g': /* return the value of the CPU registers */
1258	gdb_cmd_getregs(ks);
1259	break;
1260	case 'G': /* set the value of the CPU registers - return OK */
1261	gdb_cmd_setregs(ks);
1262	break;
1263	case 'm': /* mAA..AA,LLLL Read LLLL bytes at address AA..AA */
1264	gdb_cmd_memread(ks);
1265	break;
1266	case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1267	gdb_cmd_memwrite(ks);
1268	break;
1269	case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1270	gdb_cmd_binwrite(ks);
1271	break;
1272	/* kill or detach. KGDB should treat this like a
1273	* continue.
1274	*/
1275	case 'D': /* Debugger detach */
1276	case 'k': /* Debugger detach via kill */
1277	gdb_cmd_detachkill(ks);
1278	goto default_handle;
1279	case 'R': /* Reboot */
1280	if (gdb_cmd_reboot(ks))
1281	goto default_handle;
1282	break;
1283	case 'q': /* query command */
1284	gdb_cmd_query(ks);
1285	break;
1286	case 'H': /* task related */
1287	gdb_cmd_task(ks);
1288	break;
1289	case 'T': /* Query thread status */
1290	gdb_cmd_thread(ks);
1291	break;
1292	case 'z': /* Break point remove */
1293	case 'Z': /* Break point set */
1294	gdb_cmd_break(ks);
1295	break;
1296	case 'C': /* Exception passing */
1297	tmp = gdb_cmd_exception_pass(ks);
1298	if (tmp > 0)
1299	goto default_handle;
1300	if (tmp == 0)
1301	break;
1302	/* Fall through on tmp < 0 */
1303	case 'c': /* Continue packet */
1304	case 's': /* Single step packet */
1305	if (kgdb_contthread && kgdb_contthread != current) {
1306	/* Can't switch threads in kgdb */
1307	error_packet(remcom_out_buffer, -EINVAL);
1308	break;
1309	}
1310	kgdb_activate_sw_breakpoints();
1311	/* Fall through to default processing */
1312	default:
1313	default_handle:
1314	error = kgdb_arch_handle_exception(ks->ex_vector,
1315	ks->signo,
1316	ks->err_code,
1317	remcom_in_buffer,
1318	remcom_out_buffer,
1319	ks->linux_regs);
1320	/*
1321	* Leave cmd processing on error, detach,
1322	* kill, continue, or single step.
1323	*/
1324	if (error >= 0 \|\| remcom_in_buffer[0] == 'D' \|\|
1325	remcom_in_buffer[0] == 'k') {
1326	error = 0;
1327	goto kgdb_exit;
1328	}
1329
1330	}
1331
1332	/* reply to the request */
1333	put_packet(remcom_out_buffer);
1334	}
1335
1336	kgdb_exit:
1337	if (ks->pass_exception)
1338	error = 1;
1339	return error;
1340	}
1341
1342	static int kgdb_reenter_check(struct kgdb_state *ks)
1343	{
1344	unsigned long addr;
1345
1346	if (atomic_read(&kgdb_active) != raw_smp_processor_id())
1347	return 0;
1348
1349	/* Panic on recursive debugger calls: */
1350	exception_level++;
1351	addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
1352	kgdb_deactivate_sw_breakpoints();
1353
1354	/*
1355	* If the break point removed ok at the place exception
1356	* occurred, try to recover and print a warning to the end
1357	* user because the user planted a breakpoint in a place that
1358	* KGDB needs in order to function.
1359	*/
1360	if (kgdb_remove_sw_break(addr) == 0) {
1361	exception_level = 0;
1362	kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1363	kgdb_activate_sw_breakpoints();
1364	printk(KERN_CRIT "KGDB: re-enter error: breakpoint removed %lx\n",
1365	addr);
1366	WARN_ON_ONCE(1);
1367
1368	return 1;
1369	}
1370	remove_all_break();
1371	kgdb_skipexception(ks->ex_vector, ks->linux_regs);
1372
1373	if (exception_level > 1) {
1374	dump_stack();
1375	panic("Recursive entry to debugger");
1376	}
1377
1378	printk(KERN_CRIT "KGDB: re-enter exception: ALL breakpoints killed\n");
1379	dump_stack();
1380	panic("Recursive entry to debugger");
1381
1382	return 1;
1383	}
1384
1385	/*
1386	* kgdb_handle_exception() - main entry point from a kernel exception
1387	*
1388	* Locking hierarchy:
1389	* interface locks, if any (begin_session)
1390	* kgdb lock (kgdb_active)
1391	*/
1392	int
1393	kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
1394	{
1395	struct kgdb_state kgdb_var;
1396	struct kgdb_state *ks = &kgdb_var;
1397	unsigned long flags;
1398	int error = 0;
1399	int i, cpu;
1400
1401	ks->cpu = raw_smp_processor_id();
1402	ks->ex_vector = evector;
1403	ks->signo = signo;
1404	ks->ex_vector = evector;
1405	ks->err_code = ecode;
1406	ks->kgdb_usethreadid = 0;
1407	ks->linux_regs = regs;
1408
1409	if (kgdb_reenter_check(ks))
1410	return 0; /* Ouch, double exception ! */
1411
1412	acquirelock:
1413	/*
1414	* Interrupts will be restored by the 'trap return' code, except when
1415	* single stepping.
1416	*/
1417	local_irq_save(flags);
1418
1419	cpu = raw_smp_processor_id();
1420
1421	/*
1422	* Acquire the kgdb_active lock:
1423	*/
1424	while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1)
1425	cpu_relax();
1426
1427	/*
1428	* Do not start the debugger connection on this CPU if the last
1429	* instance of the exception handler wanted to come into the
1430	* debugger on a different CPU via a single step
1431	*/
1432	if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
1433	atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
1434
1435	atomic_set(&kgdb_active, -1);
1436	touch_softlockup_watchdog();
1437	clocksource_touch_watchdog();
1438	local_irq_restore(flags);
1439
1440	goto acquirelock;
1441	}
1442
1443	if (!kgdb_io_ready(1)) {
1444	error = 1;
1445	goto kgdb_restore; /* No I/O connection, so resume the system */
1446	}
1447
1448	/*
1449	* Don't enter if we have hit a removed breakpoint.
1450	*/
1451	if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
1452	goto kgdb_restore;
1453
1454	/* Call the I/O driver's pre_exception routine */
1455	if (kgdb_io_ops->pre_exception)
1456	kgdb_io_ops->pre_exception();
1457
1458	kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs;
1459	kgdb_info[ks->cpu].task = current;
1460
1461	kgdb_disable_hw_debug(ks->linux_regs);
1462
1463	/*
1464	* Get the passive CPU lock which will hold all the non-primary
1465	* CPU in a spin state while the debugger is active
1466	*/
1467	if (!kgdb_single_step) {
1468	for (i = 0; i < NR_CPUS; i++)
1469	atomic_set(&passive_cpu_wait[i], 1);
1470	}
1471
1472	/*
1473	* spin_lock code is good enough as a barrier so we don't
1474	* need one here:
1475	*/
1476	atomic_set(&cpu_in_kgdb[ks->cpu], 1);
1477
1478	#ifdef CONFIG_SMP
1479	/* Signal the other CPUs to enter kgdb_wait() */
1480	if ((!kgdb_single_step) && kgdb_do_roundup)
1481	kgdb_roundup_cpus(flags);
1482	#endif
1483
1484	/*
1485	* Wait for the other CPUs to be notified and be waiting for us:
1486	*/
1487	for_each_online_cpu(i) {
1488	while (!atomic_read(&cpu_in_kgdb[i]))
1489	cpu_relax();
1490	}
1491
1492	/*
1493	* At this point the primary processor is completely
1494	* in the debugger and all secondary CPUs are quiescent
1495	*/
1496	kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
1497	kgdb_deactivate_sw_breakpoints();
1498	kgdb_single_step = 0;
1499	kgdb_contthread = current;
1500	exception_level = 0;
1501
1502	/* Talk to debugger with gdbserial protocol */
1503	error = gdb_serial_stub(ks);
1504
1505	/* Call the I/O driver's post_exception routine */
1506	if (kgdb_io_ops->post_exception)
1507	kgdb_io_ops->post_exception();
1508
1509	kgdb_info[ks->cpu].debuggerinfo = NULL;
1510	kgdb_info[ks->cpu].task = NULL;
1511	atomic_set(&cpu_in_kgdb[ks->cpu], 0);
1512
1513	if (!kgdb_single_step) {
1514	for (i = NR_CPUS-1; i >= 0; i--)
1515	atomic_set(&passive_cpu_wait[i], 0);
1516	/*
1517	* Wait till all the CPUs have quit
1518	* from the debugger.
1519	*/
1520	for_each_online_cpu(i) {
1521	while (atomic_read(&cpu_in_kgdb[i]))
1522	cpu_relax();
1523	}
1524	}
1525
1526	kgdb_restore:
1527	/* Free kgdb_active */
1528	atomic_set(&kgdb_active, -1);
1529	touch_softlockup_watchdog();
1530	clocksource_touch_watchdog();
1531	local_irq_restore(flags);
1532
1533	return error;
1534	}
1535
1536	int kgdb_nmicallback(int cpu, void *regs)
1537	{
1538	#ifdef CONFIG_SMP
1539	if (!atomic_read(&cpu_in_kgdb[cpu]) &&
1540	atomic_read(&kgdb_active) != cpu &&
1541	atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) {
1542	kgdb_wait((struct pt_regs *)regs);
1543	return 0;
1544	}
1545	#endif
1546	return 1;
1547	}
1548
1549	static void kgdb_console_write(struct console co, const char s,
1550	unsigned count)
1551	{
1552	unsigned long flags;
1553
1554	/* If we're debugging, or KGDB has not connected, don't try
1555	* and print. */
1556	if (!kgdb_connected \|\| atomic_read(&kgdb_active) != -1)
1557	return;
1558
1559	local_irq_save(flags);
1560	kgdb_msg_write(s, count);
1561	local_irq_restore(flags);
1562	}
1563
1564	static struct console kgdbcons = {
1565	.name = "kgdb",
1566	.write = kgdb_console_write,
1567	.flags = CON_PRINTBUFFER \| CON_ENABLED,
1568	.index = -1,
1569	};
1570
1571	#ifdef CONFIG_MAGIC_SYSRQ
1572	static void sysrq_handle_gdb(int key, struct tty_struct *tty)
1573	{
1574	if (!kgdb_io_ops) {
1575	printk(KERN_CRIT "ERROR: No KGDB I/O module available\n");
1576	return;
1577	}
1578	if (!kgdb_connected)
1579	printk(KERN_CRIT "Entering KGDB\n");
1580
1581	kgdb_breakpoint();
1582	}
1583
1584	static struct sysrq_key_op sysrq_gdb_op = {
1585	.handler = sysrq_handle_gdb,
1586	.help_msg = "debug(G)",
1587	.action_msg = "DEBUG",
1588	};
1589	#endif
1590
1591	static void kgdb_register_callbacks(void)
1592	{
1593	if (!kgdb_io_module_registered) {
1594	kgdb_io_module_registered = 1;
1595	kgdb_arch_init();
1596	#ifdef CONFIG_MAGIC_SYSRQ
1597	register_sysrq_key('g', &sysrq_gdb_op);
1598	#endif
1599	if (kgdb_use_con && !kgdb_con_registered) {
1600	register_console(&kgdbcons);
1601	kgdb_con_registered = 1;
1602	}
1603	}
1604	}
1605
1606	static void kgdb_unregister_callbacks(void)
1607	{
1608	/*
1609	* When this routine is called KGDB should unregister from the
1610	* panic handler and clean up, making sure it is not handling any
1611	* break exceptions at the time.
1612	*/
1613	if (kgdb_io_module_registered) {
1614	kgdb_io_module_registered = 0;
1615	kgdb_arch_exit();
1616	#ifdef CONFIG_MAGIC_SYSRQ
1617	unregister_sysrq_key('g', &sysrq_gdb_op);
1618	#endif
1619	if (kgdb_con_registered) {
1620	unregister_console(&kgdbcons);
1621	kgdb_con_registered = 0;
1622	}
1623	}
1624	}
1625
1626	static void kgdb_initial_breakpoint(void)
1627	{
1628	kgdb_break_asap = 0;
1629
1630	printk(KERN_CRIT "kgdb: Waiting for connection from remote gdb...\n");
1631	kgdb_breakpoint();
1632	}
1633
1634	/**
1635	* kgdb_register_io_module - register KGDB IO module
1636	* @new_kgdb_io_ops: the io ops vector
1637	*
1638	* Register it with the KGDB core.
1639	*/
1640	int kgdb_register_io_module(struct kgdb_io *new_kgdb_io_ops)
1641	{
1642	int err;
1643
1644	spin_lock(&kgdb_registration_lock);
1645
1646	if (kgdb_io_ops) {
1647	spin_unlock(&kgdb_registration_lock);
1648
1649	printk(KERN_ERR "kgdb: Another I/O driver is already "
1650	"registered with KGDB.\n");
1651	return -EBUSY;
1652	}
1653
1654	if (new_kgdb_io_ops->init) {
1655	err = new_kgdb_io_ops->init();
1656	if (err) {
1657	spin_unlock(&kgdb_registration_lock);
1658	return err;
1659	}
1660	}
1661
1662	kgdb_io_ops = new_kgdb_io_ops;
1663
1664	spin_unlock(&kgdb_registration_lock);
1665
1666	printk(KERN_INFO "kgdb: Registered I/O driver %s.\n",
1667	new_kgdb_io_ops->name);
1668
1669	/* Arm KGDB now. */
1670	kgdb_register_callbacks();
1671
1672	if (kgdb_break_asap)
1673	kgdb_initial_breakpoint();
1674
1675	return 0;
1676	}
1677	EXPORT_SYMBOL_GPL(kgdb_register_io_module);
1678
1679	/**
1680	* kkgdb_unregister_io_module - unregister KGDB IO module
1681	* @old_kgdb_io_ops: the io ops vector
1682	*
1683	* Unregister it with the KGDB core.
1684	*/
1685	void kgdb_unregister_io_module(struct kgdb_io *old_kgdb_io_ops)
1686	{
1687	BUG_ON(kgdb_connected);
1688
1689	/*
1690	* KGDB is no longer able to communicate out, so
1691	* unregister our callbacks and reset state.
1692	*/
1693	kgdb_unregister_callbacks();
1694
1695	spin_lock(&kgdb_registration_lock);
1696
1697	WARN_ON_ONCE(kgdb_io_ops != old_kgdb_io_ops);
1698	kgdb_io_ops = NULL;
1699
1700	spin_unlock(&kgdb_registration_lock);
1701
1702	printk(KERN_INFO
1703	"kgdb: Unregistered I/O driver %s, debugger disabled.\n",
1704	old_kgdb_io_ops->name);
1705	}
1706	EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
1707
1708	/**
1709	* kgdb_breakpoint - generate breakpoint exception
1710	*
1711	* This function will generate a breakpoint exception. It is used at the
1712	* beginning of a program to sync up with a debugger and can be used
1713	* otherwise as a quick means to stop program execution and "break" into
1714	* the debugger.
1715	*/
1716	void kgdb_breakpoint(void)
1717	{
1718	atomic_set(&kgdb_setting_breakpoint, 1);
1719	wmb(); /* Sync point before breakpoint */
1720	arch_kgdb_breakpoint();
1721	wmb(); /* Sync point after breakpoint */
1722	atomic_set(&kgdb_setting_breakpoint, 0);
1723	}
1724	EXPORT_SYMBOL_GPL(kgdb_breakpoint);
1725
1726	static int __init opt_kgdb_wait(char *str)
1727	{
1728	kgdb_break_asap = 1;
1729
1730	if (kgdb_io_module_registered)
1731	kgdb_initial_breakpoint();
1732
1733	return 0;
1734	}
1735
1736	early_param("kgdbwait", opt_kgdb_wait);
1737

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