summaryrefslogtreecommitdiffstats
path: root/kernel/debug/gdbstub.c
blob: e8fd6868682d1c3f9d5736aa7a9f9148be49e75e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
/*
 * Kernel Debug Core
 *
 * Maintainer: Jason Wessel <jason.wessel@windriver.com>
 *
 * Copyright (C) 2000-2001 VERITAS Software Corporation.
 * Copyright (C) 2002-2004 Timesys Corporation
 * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
 * Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
 * Copyright (C) 2005-2009 Wind River Systems, Inc.
 * Copyright (C) 2007 MontaVista Software, Inc.
 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *
 * Contributors at various stages not listed above:
 *  Jason Wessel ( jason.wessel@windriver.com )
 *  George Anzinger <george@mvista.com>
 *  Anurekh Saxena (anurekh.saxena@timesys.com)
 *  Lake Stevens Instrument Division (Glenn Engel)
 *  Jim Kingdon, Cygnus Support.
 *
 * Original KGDB stub: David Grothe <dave@gcom.com>,
 * Tigran Aivazian <tigran@sco.com>
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2. This program is licensed "as is" without any warranty of any
 * kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/kgdb.h>
#include <linux/kdb.h>
#include <linux/reboot.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/unaligned.h>
#include "debug_core.h"

#define KGDB_MAX_THREAD_QUERY 17

/* Our I/O buffers. */
static char			remcom_in_buffer[BUFMAX];
static char			remcom_out_buffer[BUFMAX];

/* Storage for the registers, in GDB format. */
static unsigned long		gdb_regs[(NUMREGBYTES +
					sizeof(unsigned long) - 1) /
					sizeof(unsigned long)];

/*
 * GDB remote protocol parser:
 */

static int hex(char ch)
{
	if ((ch >= 'a') && (ch <= 'f'))
		return ch - 'a' + 10;
	if ((ch >= '0') && (ch <= '9'))
		return ch - '0';
	if ((ch >= 'A') && (ch <= 'F'))
		return ch - 'A' + 10;
	return -1;
}

#ifdef CONFIG_KGDB_KDB
static int gdbstub_read_wait(void)
{
	int ret = -1;
	int i;

	/* poll any additional I/O interfaces that are defined */
	while (ret < 0)
		for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
			ret = kdb_poll_funcs[i]();
			if (ret > 0)
				break;
		}
	return ret;
}
#else
static int gdbstub_read_wait(void)
{
	int ret = dbg_io_ops->read_char();
	while (ret == NO_POLL_CHAR)
		ret = dbg_io_ops->read_char();
	return ret;
}
#endif
/* scan for the sequence $<data>#<checksum> */
static void get_packet(char *buffer)
{
	unsigned char checksum;
	unsigned char xmitcsum;
	int count;
	char ch;

	do {
		/*
		 * Spin and wait around for the start character, ignore all
		 * other characters:
		 */
		while ((ch = (gdbstub_read_wait())) != '$')
			/* nothing */;

		kgdb_connected = 1;
		checksum = 0;
		xmitcsum = -1;

		count = 0;

		/*
		 * now, read until a # or end of buffer is found:
		 */
		while (count < (BUFMAX - 1)) {
			ch = gdbstub_read_wait();
			if (ch == '#')
				break;
			checksum = checksum + ch;
			buffer[count] = ch;
			count = count + 1;
		}
		buffer[count] = 0;

		if (ch == '#') {
			xmitcsum = hex(gdbstub_read_wait()) << 4;
			xmitcsum += hex(gdbstub_read_wait());

			if (checksum != xmitcsum)
				/* failed checksum */
				dbg_io_ops->write_char('-');
			else
				/* successful transfer */
				dbg_io_ops->write_char('+');
			if (dbg_io_ops->flush)
				dbg_io_ops->flush();
		}
	} while (checksum != xmitcsum);
}

/*
 * Send the packet in buffer.
 * Check for gdb connection if asked for.
 */
static void put_packet(char *buffer)
{
	unsigned char checksum;
	int count;
	char ch;

	/*
	 * $<packet info>#<checksum>.
	 */
	while (1) {
		dbg_io_ops->write_char('$');
		checksum = 0;
		count = 0;

		while ((ch = buffer[count])) {
			dbg_io_ops->write_char(ch);
			checksum += ch;
			count++;
		}

		dbg_io_ops->write_char('#');
		dbg_io_ops->write_char(hex_asc_hi(checksum));
		dbg_io_ops->write_char(hex_asc_lo(checksum));
		if (dbg_io_ops->flush)
			dbg_io_ops->flush();

		/* Now see what we get in reply. */
		ch = gdbstub_read_wait();

		if (ch == 3)
			ch = gdbstub_read_wait();

		/* If we get an ACK, we are done. */
		if (ch == '+')
			return;

		/*
		 * If we get the start of another packet, this means
		 * that GDB is attempting to reconnect.  We will NAK
		 * the packet being sent, and stop trying to send this
		 * packet.
		 */
		if (ch == '$') {
			dbg_io_ops->write_char('-');
			if (dbg_io_ops->flush)
				dbg_io_ops->flush();
			return;
		}
	}
}

static char gdbmsgbuf[BUFMAX + 1];

void gdbstub_msg_write(const char *s, int len)
{
	char *bufptr;
	int wcount;
	int i;

	if (len == 0)
		len = strlen(s);

	/* 'O'utput */
	gdbmsgbuf[0] = 'O';

	/* Fill and send buffers... */
	while (len > 0) {
		bufptr = gdbmsgbuf + 1;

		/* Calculate how many this time */
		if ((len << 1) > (BUFMAX - 2))
			wcount = (BUFMAX - 2) >> 1;
		else
			wcount = len;

		/* Pack in hex chars */
		for (i = 0; i < wcount; i++)
			bufptr = pack_hex_byte(bufptr, s[i]);
		*bufptr = '\0';

		/* Move up */
		s += wcount;
		len -= wcount;

		/* Write packet */
		put_packet(gdbmsgbuf);
	}
}

/*
 * Convert the memory pointed to by mem into hex, placing result in
 * buf.  Return a pointer to the last char put in buf (null). May
 * return an error.
 */
int kgdb_mem2hex(char *mem, char *buf, int count)
{
	char *tmp;
	int err;

	/*
	 * We use the upper half of buf as an intermediate buffer for the
	 * raw memory copy.  Hex conversion will work against this one.
	 */
	tmp = buf + count;

	err = probe_kernel_read(tmp, mem, count);
	if (!err) {
		while (count > 0) {
			buf = pack_hex_byte(buf, *tmp);
			tmp++;
			count--;
		}

		*buf = 0;
	}

	return err;
}

/*
 * Convert the hex array pointed to by buf into binary to be placed in
 * mem.  Return a pointer to the character AFTER the last byte
 * written.  May return an error.
 */
int kgdb_hex2mem(char *buf, char *mem, int count)
{
	char *tmp_raw;
	char *tmp_hex;

	/*
	 * We use the upper half of buf as an intermediate buffer for the
	 * raw memory that is converted from hex.
	 */
	tmp_raw = buf + count * 2;

	tmp_hex = tmp_raw - 1;
	while (tmp_hex >= buf) {
		tmp_raw--;
		*tmp_raw = hex(*tmp_hex--);
		*tmp_raw |= hex(*tmp_hex--) << 4;
	}

	return probe_kernel_write(mem, tmp_raw, count);
}

/*
 * While we find nice hex chars, build a long_val.
 * Return number of chars processed.
 */
int kgdb_hex2long(char **ptr, unsigned long *long_val)
{
	int hex_val;
	int num = 0;
	int negate = 0;

	*long_val = 0;

	if (**ptr == '-') {
		negate = 1;
		(*ptr)++;
	}
	while (**ptr) {
		hex_val = hex(**ptr);
		if (hex_val < 0)
			break;

		*long_val = (*long_val << 4) | hex_val;
		num++;
		(*ptr)++;
	}

	if (negate)
		*long_val = -*long_val;

	return num;
}

/*
 * Copy the binary array pointed to by buf into mem.  Fix $, #, and
 * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
 * The input buf is overwitten with the result to write to mem.
 */
static int kgdb_ebin2mem(char *buf, char *mem, int count)
{
	int size = 0;
	char *c = buf;

	while (count-- > 0) {
		c[size] = *buf++;
		if (c[size] == 0x7d)
			c[size] = *buf++ ^ 0x20;
		size++;
	}

	return probe_kernel_write(mem, c, size);
}

/* Write memory due to an 'M' or 'X' packet. */
static int write_mem_msg(int binary)
{
	char *ptr = &remcom_in_buffer[1];
	unsigned long addr;
	unsigned long length;
	int err;

	if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
	    kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
		if (binary)
			err = kgdb_ebin2mem(ptr, (char *)addr, length);
		else
			err = kgdb_hex2mem(ptr, (char *)addr, length);
		if (err)
			return err;
		if (CACHE_FLUSH_IS_SAFE)
			flush_icache_range(addr, addr + length);
		return 0;
	}

	return -EINVAL;
}

static void error_packet(char *pkt, int error)
{
	error = -error;
	pkt[0] = 'E';
	pkt[1] = hex_asc[(error / 10)];
	pkt[2] = hex_asc[(error % 10)];
	pkt[3] = '\0';
}

/*
 * Thread ID accessors. We represent a flat TID space to GDB, where
 * the per CPU idle threads (which under Linux all have PID 0) are
 * remapped to negative TIDs.
 */

#define BUF_THREAD_ID_SIZE	16

static char *pack_threadid(char *pkt, unsigned char *id)
{
	char *limit;

	limit = pkt + BUF_THREAD_ID_SIZE;
	while (pkt < limit)
		pkt = pack_hex_byte(pkt, *id++);

	return pkt;
}

static void int_to_threadref(unsigned char *id, int value)
{
	unsigned char *scan;
	int i = 4;

	scan = (unsigned char *)id;
	while (i--)
		*scan++ = 0;
	put_unaligned_be32(value, scan);
}

static struct task_struct *getthread(struct pt_regs *regs, int tid)
{
	/*
	 * Non-positive TIDs are remapped to the cpu shadow information
	 */
	if (tid == 0 || tid == -1)
		tid = -atomic_read(&kgdb_active) - 2;
	if (tid < -1 && tid > -NR_CPUS - 2) {
		if (kgdb_info[-tid - 2].task)
			return kgdb_info[-tid - 2].task;
		else
			return idle_task(-tid - 2);
	}
	if (tid <= 0) {
		printk(KERN_ERR "KGDB: Internal thread select error\n");
		dump_stack();
		return NULL;
	}

	/*
	 * find_task_by_pid_ns() does not take the tasklist lock anymore
	 * but is nicely RCU locked - hence is a pretty resilient
	 * thing to use:
	 */
	return find_task_by_pid_ns(tid, &init_pid_ns);
}


/*
 * Remap normal tasks to their real PID,
 * CPU shadow threads are mapped to -CPU - 2
 */
static inline int shadow_pid(int realpid)
{
	if (realpid)
		return realpid;

	return -raw_smp_processor_id() - 2;
}

/*
 * All the functions that start with gdb_cmd are the various
 * operations to implement the handlers for the gdbserial protocol
 * where KGDB is communicating with an external debugger
 */

/* Handle the '?' status packets */
static void gdb_cmd_status(struct kgdb_state *ks)
{
	/*
	 * We know that this packet is only sent
	 * during initial connect.  So to be safe,
	 * we clear out our breakpoints now in case
	 * GDB is reconnecting.
	 */
	dbg_remove_all_break();

	remcom_out_buffer[0] = 'S';
	pack_hex_byte(&remcom_out_buffer[1], ks->signo);
}

/* Handle the 'g' get registers request */
static void gdb_cmd_getregs(struct kgdb_state *ks)
{
	struct task_struct *thread;
	void *local_debuggerinfo;
	int i;

	thread = kgdb_usethread;
	if (!thread) {
		thread = kgdb_info[ks->cpu].task;
		local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
	} else {
		local_debuggerinfo = NULL;
		for_each_online_cpu(i) {
			/*
			 * Try to find the task on some other
			 * or possibly this node if we do not
			 * find the matching task then we try
			 * to approximate the results.
			 */
			if (thread == kgdb_info[i].task)
				local_debuggerinfo = kgdb_info[i].debuggerinfo;
		}
	}

	/*
	 * All threads that don't have debuggerinfo should be
	 * in schedule() sleeping, since all other CPUs
	 * are in kgdb_wait, and thus have debuggerinfo.
	 */
	if (local_debuggerinfo) {
		pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
	} else {
		/*
		 * Pull stuff saved during switch_to; nothing
		 * else is accessible (or even particularly
		 * relevant).
		 *
		 * This should be enough for a stack trace.
		 */
		sleeping_thread_to_gdb_regs(gdb_regs, thread);
	}
	kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
}

/* Handle the 'G' set registers request */
static void gdb_cmd_setregs(struct kgdb_state *ks)
{
	kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);

	if (kgdb_usethread && kgdb_usethread != current) {
		error_packet(remcom_out_buffer, -EINVAL);
	} else {
		gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
		strcpy(remcom_out_buffer, "OK");
	}
}

/* Handle the 'm' memory read bytes */
static void gdb_cmd_memread(struct kgdb_state *ks)
{
	char *ptr = &remcom_in_buffer[1];
	unsigned long length;
	unsigned long addr;
	int err;

	if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
					kgdb_hex2long(&ptr, &length) > 0) {
		err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
		if (err)
			error_packet(remcom_out_buffer, err);
	} else {
		error_packet(remcom_out_buffer, -EINVAL);
	}
}

/* Handle the 'M' memory write bytes */
static void gdb_cmd_memwrite(struct kgdb_state *ks)
{
	int err = write_mem_msg(0);

	if (err)
		error_packet(remcom_out_buffer, err);
	else
		strcpy(remcom_out_buffer, "OK");
}

/* Handle the 'X' memory binary write bytes */
static void gdb_cmd_binwrite(struct kgdb_state *ks)
{
	int err = write_mem_msg(1);

	if (err)
		error_packet(remcom_out_buffer, err);
	else
		strcpy(remcom_out_buffer, "OK");
}

/* Handle the 'D' or 'k', detach or kill packets */
static void gdb_cmd_detachkill(struct kgdb_state *ks)
{
	int error;

	/* The detach case */
	if (remcom_in_buffer[0] == 'D') {
		error = dbg_remove_all_break();
		if (error < 0) {
			error_packet(remcom_out_buffer, error);
		} else {
			strcpy(remcom_out_buffer, "OK");
			kgdb_connected = 0;
		}
		put_packet(remcom_out_buffer);
	} else {
		/*
		 * Assume the kill case, with no exit code checking,
		 * trying to force detach the debugger:
		 */
		dbg_remove_all_break();
		kgdb_connected = 0;
	}
}

/* Handle the 'R' reboot packets */
static int gdb_cmd_reboot(struct kgdb_state *ks)
{
	/* For now, only honor R0 */
	if (strcmp(remcom_in_buffer, "R0") == 0) {
		printk(KERN_CRIT "Executing emergency reboot\n");
		strcpy(remcom_out_buffer, "OK");
		put_packet(remcom_out_buffer);

		/*
		 * Execution should not return from
		 * machine_emergency_restart()
		 */
		machine_emergency_restart();
		kgdb_connected = 0;

		return 1;
	}
	return 0;
}

/* Handle the 'q' query packets */
static void gdb_cmd_query(struct kgdb_state *ks)
{
	struct task_struct *g;
	struct task_struct *p;
	unsigned char thref[8];
	char *ptr;
	int i;
	int cpu;
	int finished = 0;

	switch (remcom_in_buffer[1]) {
	case 's':
	case 'f':
		if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
			break;

		i = 0;
		remcom_out_buffer[0] = 'm';
		ptr = remcom_out_buffer + 1;
		if (remcom_in_buffer[1] == 'f') {
			/* Each cpu is a shadow thread */
			for_each_online_cpu(cpu) {
				ks->thr_query = 0;
				int_to_threadref(thref, -cpu - 2);
				pack_threadid(ptr, thref);
				ptr += BUF_THREAD_ID_SIZE;
				*(ptr++) = ',';
				i++;
			}
		}

		do_each_thread(g, p) {
			if (i >= ks->thr_query && !finished) {
				int_to_threadref(thref, p->pid);
				pack_threadid(ptr, thref);
				ptr += BUF_THREAD_ID_SIZE;
				*(ptr++) = ',';
				ks->thr_query++;
				if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
					finished = 1;
			}
			i++;
		} while_each_thread(g, p);

		*(--ptr) = '\0';
		break;

	case 'C':
		/* Current thread id */
		strcpy(remcom_out_buffer, "QC");
		ks->threadid = shadow_pid(current->pid);
		int_to_threadref(thref, ks->threadid);
		pack_threadid(remcom_out_buffer + 2, thref);
		break;
	case 'T':
		if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
			break;

		ks->threadid = 0;
		ptr = remcom_in_buffer + 17;
		kgdb_hex2long(&ptr, &ks->threadid);
		if (!getthread(ks->linux_regs, ks->threadid)) {
			error_packet(remcom_out_buffer, -EINVAL);
			break;
		}
		if ((int)ks->threadid > 0) {
			kgdb_mem2hex(getthread(ks->linux_regs,
					ks->threadid)->comm,
					remcom_out_buffer, 16);
		} else {
			static char tmpstr[23 + BUF_THREAD_ID_SIZE];

			sprintf(tmpstr, "shadowCPU%d",
					(int)(-ks->threadid - 2));
			kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
		}
		break;
#ifdef CONFIG_KGDB_KDB
	case 'R':
		if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
			int len = strlen(remcom_in_buffer + 6);

			if ((len % 2) != 0) {
				strcpy(remcom_out_buffer, "E01");
				break;
			}
			kgdb_hex2mem(remcom_in_buffer + 6,
				     remcom_out_buffer, len);
			len = len / 2;
			remcom_out_buffer[len++] = 0;

			kdb_parse(remcom_out_buffer);
			strcpy(remcom_out_buffer, "OK");
		}
		break;
#endif
	}
}

/* Handle the 'H' task query packets */
static void gdb_cmd_task(struct kgdb_state *ks)
{
	struct task_struct *thread;
	char *ptr;

	switch (remcom_in_buffer[1]) {
	case 'g':
		ptr = &remcom_in_buffer[2];
		kgdb_hex2long(&ptr, &ks->threadid);
		thread = getthread(ks->linux_regs, ks->threadid);
		if (!thread && ks->threadid > 0) {
			error_packet(remcom_out_buffer, -EINVAL);
			break;
		}
		kgdb_usethread = thread;
		ks->kgdb_usethreadid = ks->threadid;
		strcpy(remcom_out_buffer, "OK");
		break;
	case 'c':
		ptr = &remcom_in_buffer[2];
		kgdb_hex2long(&ptr, &ks->threadid);
		if (!ks->threadid) {
			kgdb_contthread = NULL;
		} else {
			thread = getthread(ks->linux_regs, ks->threadid);
			if (!thread && ks->threadid > 0) {
				error_packet(remcom_out_buffer, -EINVAL);
				break;
			}
			kgdb_contthread = thread;
		}
		strcpy(remcom_out_buffer, "OK");
		break;
	}
}

/* Handle the 'T' thread query packets */
static void gdb_cmd_thread(struct kgdb_state *ks)
{
	char *ptr = &remcom_in_buffer[1];
	struct task_struct *thread;

	kgdb_hex2long(&ptr, &ks->threadid);
	thread = getthread(ks->linux_regs, ks->threadid);
	if (thread)
		strcpy(remcom_out_buffer, "OK");
	else
		error_packet(remcom_out_buffer, -EINVAL);
}

/* Handle the 'z' or 'Z' breakpoint remove or set packets */
static void gdb_cmd_break(struct kgdb_state *ks)
{
	/*
	 * Since GDB-5.3, it's been drafted that '0' is a software
	 * breakpoint, '1' is a hardware breakpoint, so let's do that.
	 */
	char *bpt_type = &remcom_in_buffer[1];
	char *ptr = &remcom_in_buffer[2];
	unsigned long addr;
	unsigned long length;
	int error = 0;

	if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
		/* Unsupported */
		if (*bpt_type > '4')
			return;
	} else {
		if (*bpt_type != '0' && *bpt_type != '1')
			/* Unsupported. */
			return;
	}

	/*
	 * Test if this is a hardware breakpoint, and
	 * if we support it:
	 */
	if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
		/* Unsupported. */
		return;

	if (*(ptr++) != ',') {
		error_packet(remcom_out_buffer, -EINVAL);
		return;
	}
	if (!kgdb_hex2long(&ptr, &addr)) {
		error_packet(remcom_out_buffer, -EINVAL);
		return;
	}
	if (*(ptr++) != ',' ||
		!kgdb_hex2long(&ptr, &length)) {
		error_packet(remcom_out_buffer, -EINVAL);
		return;
	}

	if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
		error = dbg_set_sw_break(addr);
	else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
		error = dbg_remove_sw_break(addr);
	else if (remcom_in_buffer[0] == 'Z')
		error = arch_kgdb_ops.set_hw_breakpoint(addr,
			(int)length, *bpt_type - '0');
	else if (remcom_in_buffer[0] == 'z')
		error = arch_kgdb_ops.remove_hw_breakpoint(addr,
			(int) length, *bpt_type - '0');

	if (error == 0)
		strcpy(remcom_out_buffer, "OK");
	else
		error_packet(remcom_out_buffer, error);
}

/* Handle the 'C' signal / exception passing packets */
static int gdb_cmd_exception_pass(struct kgdb_state *ks)
{
	/* C09 == pass exception
	 * C15 == detach kgdb, pass exception
	 */
	if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {

		ks->pass_exception = 1;
		remcom_in_buffer[0] = 'c';

	} else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {

		ks->pass_exception = 1;
		remcom_in_buffer[0] = 'D';
		dbg_remove_all_break();
		kgdb_connected = 0;
		return 1;

	} else {
		gdbstub_msg_write("KGDB only knows signal 9 (pass)"
			" and 15 (pass and disconnect)\n"
			"Executing a continue without signal passing\n", 0);
		remcom_in_buffer[0] = 'c';
	}

	/* Indicate fall through */
	return -1;
}

/*
 * This function performs all gdbserial command procesing
 */
int gdb_serial_stub(struct kgdb_state *ks)
{
	int error = 0;
	int tmp;

	/* Clear the out buffer. */
	memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));

	if (kgdb_connected) {
		unsigned char thref[8];
		char *ptr;

		/* Reply to host that an exception has occurred */
		ptr = remcom_out_buffer;
		*ptr++ = 'T';
		ptr = pack_hex_byte(ptr, ks->signo);
		ptr += strlen(strcpy(ptr, "thread:"));
		int_to_threadref(thref, shadow_pid(current->pid));
		ptr = pack_threadid(ptr, thref);
		*ptr++ = ';';
		put_packet(remcom_out_buffer);
	}

	kgdb_usethread = kgdb_info[ks->cpu].task;
	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
	ks->pass_exception = 0;

	while (1) {
		error = 0;

		/* Clear the out buffer. */
		memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));

		get_packet(remcom_in_buffer);

		switch (remcom_in_buffer[0]) {
		case '?': /* gdbserial status */
			gdb_cmd_status(ks);
			break;
		case 'g': /* return the value of the CPU registers */
			gdb_cmd_getregs(ks);
			break;
		case 'G': /* set the value of the CPU registers - return OK */
			gdb_cmd_setregs(ks);
			break;
		case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
			gdb_cmd_memread(ks);
			break;
		case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
			gdb_cmd_memwrite(ks);
			break;
		case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
			gdb_cmd_binwrite(ks);
			break;
			/* kill or detach. KGDB should treat this like a
			 * continue.
			 */
		case 'D': /* Debugger detach */
		case 'k': /* Debugger detach via kill */
			gdb_cmd_detachkill(ks);
			goto default_handle;
		case 'R': /* Reboot */
			if (gdb_cmd_reboot(ks))
				goto default_handle;
			break;
		case 'q': /* query command */
			gdb_cmd_query(ks);
			break;
		case 'H': /* task related */
			gdb_cmd_task(ks);
			break;
		case 'T': /* Query thread status */
			gdb_cmd_thread(ks);
			break;
		case 'z': /* Break point remove */
		case 'Z': /* Break point set */
			gdb_cmd_break(ks);
			break;
#ifdef CONFIG_KGDB_KDB
		case '3': /* Escape into back into kdb */
			if (remcom_in_buffer[1] == '\0') {
				gdb_cmd_detachkill(ks);
				return DBG_PASS_EVENT;
			}
#endif
		case 'C': /* Exception passing */
			tmp = gdb_cmd_exception_pass(ks);
			if (tmp > 0)
				goto default_handle;
			if (tmp == 0)
				break;
			/* Fall through on tmp < 0 */
		case 'c': /* Continue packet */
		case 's': /* Single step packet */
			if (kgdb_contthread && kgdb_contthread != current) {
				/* Can't switch threads in kgdb */
				error_packet(remcom_out_buffer, -EINVAL);
				break;
			}
			dbg_activate_sw_breakpoints();
			/* Fall through to default processing */
		default:
default_handle:
			error = kgdb_arch_handle_exception(ks->ex_vector,
						ks->signo,
						ks->err_code,
						remcom_in_buffer,
						remcom_out_buffer,
						ks->linux_regs);
			/*
			 * Leave cmd processing on error, detach,
			 * kill, continue, or single step.
			 */
			if (error >= 0 || remcom_in_buffer[0] == 'D' ||
			    remcom_in_buffer[0] == 'k') {
				error = 0;
				goto kgdb_exit;
			}

		}

		/* reply to the request */
		put_packet(remcom_out_buffer);
	}

kgdb_exit:
	if (ks->pass_exception)
		error = 1;
	return error;
}

int gdbstub_state(struct kgdb_state *ks, char *cmd)
{
	int error;

	switch (cmd[0]) {
	case 'e':
		error = kgdb_arch_handle_exception(ks->ex_vector,
						   ks->signo,
						   ks->err_code,
						   remcom_in_buffer,
						   remcom_out_buffer,
						   ks->linux_regs);
		return error;
	case 's':
	case 'c':
		strcpy(remcom_in_buffer, cmd);
		return 0;
	case '?':
		gdb_cmd_status(ks);
		break;
	case '\0':
		strcpy(remcom_out_buffer, "");
		break;
	}
	dbg_io_ops->write_char('+');
	put_packet(remcom_out_buffer);
	return 0;
}
OpenPOWER on IntegriCloud