1
// SPDX-License-Identifier: GPL-2.0-only
2
/*
3
 * Kernel Debug Core
4
 *
5
 * Maintainer: Jason Wessel <[email protected]>
6
 *
7
 * Copyright (C) 2000-2001 VERITAS Software Corporation.
8
 * Copyright (C) 2002-2004 Timesys Corporation
9
 * Copyright (C) 2003-2004 Amit S. Kale <[email protected]>
10
 * Copyright (C) 2004 Pavel Machek <[email protected]>
11
 * Copyright (C) 2004-2006 Tom Rini <[email protected]>
12
 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
13
 * Copyright (C) 2005-2009 Wind River Systems, Inc.
14
 * Copyright (C) 2007 MontaVista Software, Inc.
15
 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <[email protected]>
16
 *
17
 * Contributors at various stages not listed above:
18
 *  Jason Wessel ( [email protected] )
19
 *  George Anzinger <[email protected]>
20
 *  Anurekh Saxena ([email protected])
21
 *  Lake Stevens Instrument Division (Glenn Engel)
22
 *  Jim Kingdon, Cygnus Support.
23
 *
24
 * Original KGDB stub: David Grothe <[email protected]>,
25
 * Tigran Aivazian <[email protected]>
26
 */
27

28
#include <linux/kernel.h>
29
#include <linux/sched/signal.h>
30
#include <linux/kgdb.h>
31
#include <linux/kdb.h>
32
#include <linux/serial_core.h>
33
#include <linux/string.h>
34
#include <linux/reboot.h>
35
#include <linux/uaccess.h>
36
#include <asm/cacheflush.h>
37
#include <linux/unaligned.h>
38
#include "debug_core.h"
39

40
#define KGDB_MAX_THREAD_QUERY 17
41

42
/* Our I/O buffers. */
43
static char			remcom_in_buffer[BUFMAX];
44
static char			remcom_out_buffer[BUFMAX];
45
static int			gdbstub_use_prev_in_buf;
46
static int			gdbstub_prev_in_buf_pos;
47

48
/* Storage for the registers, in GDB format. */
49
static unsigned long		gdb_regs[(NUMREGBYTES +
50
					sizeof(unsigned long) - 1) /
51
					sizeof(unsigned long)];
52

53
/*
54
 * GDB remote protocol parser:
55
 */
56

57
#ifdef CONFIG_KGDB_KDB
58
static int gdbstub_read_wait(void)
59
{
60
	int ret = -1;
61
	int i;
62

63
	if (unlikely(gdbstub_use_prev_in_buf)) {
64
		if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
65
			return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
66
		else
67
			gdbstub_use_prev_in_buf = 0;
68
	}
69

70
	/* poll any additional I/O interfaces that are defined */
71
	while (ret < 0)
72
		for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
73
			ret = kdb_poll_funcs[i]();
74
			if (ret > 0)
75
				break;
76
		}
77
	return ret;
78
}
79
#else
80
static int gdbstub_read_wait(void)
81
{
82
	int ret = dbg_io_ops->read_char();
83
	while (ret == NO_POLL_CHAR)
84
		ret = dbg_io_ops->read_char();
85
	return ret;
86
}
87
#endif
88
/* scan for the sequence $<data>#<checksum> */
89
static void get_packet(char *buffer)
90
{
91
	unsigned char checksum;
92
	unsigned char xmitcsum;
93
	int count;
94
	char ch;
95

96
	do {
97
		/*
98
		 * Spin and wait around for the start character, ignore all
99
		 * other characters:
100
		 */
101
		while ((ch = (gdbstub_read_wait())) != '$')
102
			/* nothing */;
103

104
		kgdb_connected = 1;
105
		checksum = 0;
106
		xmitcsum = -1;
107

108
		count = 0;
109

110
		/*
111
		 * now, read until a # or end of buffer is found:
112
		 */
113
		while (count < (BUFMAX - 1)) {
114
			ch = gdbstub_read_wait();
115
			if (ch == '#')
116
				break;
117
			checksum = checksum + ch;
118
			buffer[count] = ch;
119
			count = count + 1;
120
		}
121

122
		if (ch == '#') {
123
			xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
124
			xmitcsum += hex_to_bin(gdbstub_read_wait());
125

126
			if (checksum != xmitcsum)
127
				/* failed checksum */
128
				dbg_io_ops->write_char('-');
129
			else
130
				/* successful transfer */
131
				dbg_io_ops->write_char('+');
132
			if (dbg_io_ops->flush)
133
				dbg_io_ops->flush();
134
		}
135
		buffer[count] = 0;
136
	} while (checksum != xmitcsum);
137
}
138

139
/*
140
 * Send the packet in buffer.
141
 * Check for gdb connection if asked for.
142
 */
143
static void put_packet(char *buffer)
144
{
145
	unsigned char checksum;
146
	int count;
147
	char ch;
148

149
	/*
150
	 * $<packet info>#<checksum>.
151
	 */
152
	while (1) {
153
		dbg_io_ops->write_char('$');
154
		checksum = 0;
155
		count = 0;
156

157
		while ((ch = buffer[count])) {
158
			dbg_io_ops->write_char(ch);
159
			checksum += ch;
160
			count++;
161
		}
162

163
		dbg_io_ops->write_char('#');
164
		dbg_io_ops->write_char(hex_asc_hi(checksum));
165
		dbg_io_ops->write_char(hex_asc_lo(checksum));
166
		if (dbg_io_ops->flush)
167
			dbg_io_ops->flush();
168

169
		/* Now see what we get in reply. */
170
		ch = gdbstub_read_wait();
171

172
		if (ch == 3)
173
			ch = gdbstub_read_wait();
174

175
		/* If we get an ACK, we are done. */
176
		if (ch == '+')
177
			return;
178

179
		/*
180
		 * If we get the start of another packet, this means
181
		 * that GDB is attempting to reconnect.  We will NAK
182
		 * the packet being sent, and stop trying to send this
183
		 * packet.
184
		 */
185
		if (ch == '$') {
186
			dbg_io_ops->write_char('-');
187
			if (dbg_io_ops->flush)
188
				dbg_io_ops->flush();
189
			return;
190
		}
191
	}
192
}
193

194
static char gdbmsgbuf[BUFMAX + 1];
195

196
void gdbstub_msg_write(const char *s, int len)
197
{
198
	char *bufptr;
199
	int wcount;
200
	int i;
201

202
	if (len == 0)
203
		len = strlen(s);
204

205
	/* 'O'utput */
206
	gdbmsgbuf[0] = 'O';
207

208
	/* Fill and send buffers... */
209
	while (len > 0) {
210
		bufptr = gdbmsgbuf + 1;
211

212
		/* Calculate how many this time */
213
		if ((len << 1) > (BUFMAX - 2))
214
			wcount = (BUFMAX - 2) >> 1;
215
		else
216
			wcount = len;
217

218
		/* Pack in hex chars */
219
		for (i = 0; i < wcount; i++)
220
			bufptr = hex_byte_pack(bufptr, s[i]);
221
		*bufptr = '\0';
222

223
		/* Move up */
224
		s += wcount;
225
		len -= wcount;
226

227
		/* Write packet */
228
		put_packet(gdbmsgbuf);
229
	}
230
}
231

232
/*
233
 * Convert the memory pointed to by mem into hex, placing result in
234
 * buf.  Return a pointer to the last char put in buf (null). May
235
 * return an error.
236
 */
237
char *kgdb_mem2hex(char *mem, char *buf, int count)
238
{
239
	char *tmp;
240
	int err;
241

242
	/*
243
	 * We use the upper half of buf as an intermediate buffer for the
244
	 * raw memory copy.  Hex conversion will work against this one.
245
	 */
246
	tmp = buf + count;
247

248
	err = copy_from_kernel_nofault(tmp, mem, count);
249
	if (err)
250
		return NULL;
251
	while (count > 0) {
252
		buf = hex_byte_pack(buf, *tmp);
253
		tmp++;
254
		count--;
255
	}
256
	*buf = 0;
257

258
	return buf;
259
}
260

261
/*
262
 * Convert the hex array pointed to by buf into binary to be placed in
263
 * mem.  Return a pointer to the character AFTER the last byte
264
 * written.  May return an error.
265
 */
266
int kgdb_hex2mem(char *buf, char *mem, int count)
267
{
268
	char *tmp_raw;
269
	char *tmp_hex;
270

271
	/*
272
	 * We use the upper half of buf as an intermediate buffer for the
273
	 * raw memory that is converted from hex.
274
	 */
275
	tmp_raw = buf + count * 2;
276

277
	tmp_hex = tmp_raw - 1;
278
	while (tmp_hex >= buf) {
279
		tmp_raw--;
280
		*tmp_raw = hex_to_bin(*tmp_hex--);
281
		*tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
282
	}
283

284
	return copy_to_kernel_nofault(mem, tmp_raw, count);
285
}
286

287
/*
288
 * While we find nice hex chars, build a long_val.
289
 * Return number of chars processed.
290
 */
291
int kgdb_hex2long(char **ptr, unsigned long *long_val)
292
{
293
	int hex_val;
294
	int num = 0;
295
	int negate = 0;
296

297
	*long_val = 0;
298

299
	if (**ptr == '-') {
300
		negate = 1;
301
		(*ptr)++;
302
	}
303
	while (**ptr) {
304
		hex_val = hex_to_bin(**ptr);
305
		if (hex_val < 0)
306
			break;
307

308
		*long_val = (*long_val << 4) | hex_val;
309
		num++;
310
		(*ptr)++;
311
	}
312

313
	if (negate)
314
		*long_val = -*long_val;
315

316
	return num;
317
}
318

319
/*
320
 * Copy the binary array pointed to by buf into mem.  Fix $, #, and
321
 * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
322
 * The input buf is overwritten with the result to write to mem.
323
 */
324
static int kgdb_ebin2mem(char *buf, char *mem, int count)
325
{
326
	int size = 0;
327
	char *c = buf;
328

329
	while (count-- > 0) {
330
		c[size] = *buf++;
331
		if (c[size] == 0x7d)
332
			c[size] = *buf++ ^ 0x20;
333
		size++;
334
	}
335

336
	return copy_to_kernel_nofault(mem, c, size);
337
}
338

339
#if DBG_MAX_REG_NUM > 0
340
void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
341
{
342
	int i;
343
	int idx = 0;
344
	char *ptr = (char *)gdb_regs;
345

346
	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
347
		dbg_get_reg(i, ptr + idx, regs);
348
		idx += dbg_reg_def[i].size;
349
	}
350
}
351

352
void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
353
{
354
	int i;
355
	int idx = 0;
356
	char *ptr = (char *)gdb_regs;
357

358
	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
359
		dbg_set_reg(i, ptr + idx, regs);
360
		idx += dbg_reg_def[i].size;
361
	}
362
}
363
#endif /* DBG_MAX_REG_NUM > 0 */
364

365
/* Write memory due to an 'M' or 'X' packet. */
366
static int write_mem_msg(int binary)
367
{
368
	char *ptr = &remcom_in_buffer[1];
369
	unsigned long addr;
370
	unsigned long length;
371
	int err;
372

373
	if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
374
	    kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
375
		if (binary)
376
			err = kgdb_ebin2mem(ptr, (char *)addr, length);
377
		else
378
			err = kgdb_hex2mem(ptr, (char *)addr, length);
379
		if (err)
380
			return err;
381
		if (CACHE_FLUSH_IS_SAFE)
382
			flush_icache_range(addr, addr + length);
383
		return 0;
384
	}
385

386
	return -EINVAL;
387
}
388

389
static void error_packet(char *pkt, int error)
390
{
391
	error = -error;
392
	pkt[0] = 'E';
393
	pkt[1] = hex_asc[(error / 10)];
394
	pkt[2] = hex_asc[(error % 10)];
395
	pkt[3] = '\0';
396
}
397

398
/*
399
 * Thread ID accessors. We represent a flat TID space to GDB, where
400
 * the per CPU idle threads (which under Linux all have PID 0) are
401
 * remapped to negative TIDs.
402
 */
403

404
#define BUF_THREAD_ID_SIZE	8
405

406
static char *pack_threadid(char *pkt, unsigned char *id)
407
{
408
	unsigned char *limit;
409
	int lzero = 1;
410

411
	limit = id + (BUF_THREAD_ID_SIZE / 2);
412
	while (id < limit) {
413
		if (!lzero || *id != 0) {
414
			pkt = hex_byte_pack(pkt, *id);
415
			lzero = 0;
416
		}
417
		id++;
418
	}
419

420
	if (lzero)
421
		pkt = hex_byte_pack(pkt, 0);
422

423
	return pkt;
424
}
425

426
static void int_to_threadref(unsigned char *id, int value)
427
{
428
	put_unaligned_be32(value, id);
429
}
430

431
static struct task_struct *getthread(struct pt_regs *regs, int tid)
432
{
433
	/*
434
	 * Non-positive TIDs are remapped to the cpu shadow information
435
	 */
436
	if (tid == 0 || tid == -1)
437
		tid = -atomic_read(&kgdb_active) - 2;
438
	if (tid < -1 && tid > -NR_CPUS - 2) {
439
		if (kgdb_info[-tid - 2].task)
440
			return kgdb_info[-tid - 2].task;
441
		else
442
			return idle_task(-tid - 2);
443
	}
444
	if (tid <= 0) {
445
		printk(KERN_ERR "KGDB: Internal thread select error\n");
446
		dump_stack();
447
		return NULL;
448
	}
449

450
	/*
451
	 * find_task_by_pid_ns() does not take the tasklist lock anymore
452
	 * but is nicely RCU locked - hence is a pretty resilient
453
	 * thing to use:
454
	 */
455
	return find_task_by_pid_ns(tid, &init_pid_ns);
456
}
457

458

459
/*
460
 * Remap normal tasks to their real PID,
461
 * CPU shadow threads are mapped to -CPU - 2
462
 */
463
static inline int shadow_pid(int realpid)
464
{
465
	if (realpid)
466
		return realpid;
467

468
	return -raw_smp_processor_id() - 2;
469
}
470

471
/*
472
 * All the functions that start with gdb_cmd are the various
473
 * operations to implement the handlers for the gdbserial protocol
474
 * where KGDB is communicating with an external debugger
475
 */
476

477
/* Handle the '?' status packets */
478
static void gdb_cmd_status(struct kgdb_state *ks)
479
{
480
	/*
481
	 * We know that this packet is only sent
482
	 * during initial connect.  So to be safe,
483
	 * we clear out our breakpoints now in case
484
	 * GDB is reconnecting.
485
	 */
486
	dbg_remove_all_break();
487

488
	remcom_out_buffer[0] = 'S';
489
	hex_byte_pack(&remcom_out_buffer[1], ks->signo);
490
}
491

492
static void gdb_get_regs_helper(struct kgdb_state *ks)
493
{
494
	struct task_struct *thread;
495
	void *local_debuggerinfo;
496
	int i;
497

498
	thread = kgdb_usethread;
499
	if (!thread) {
500
		thread = kgdb_info[ks->cpu].task;
501
		local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
502
	} else {
503
		local_debuggerinfo = NULL;
504
		for_each_online_cpu(i) {
505
			/*
506
			 * Try to find the task on some other
507
			 * or possibly this node if we do not
508
			 * find the matching task then we try
509
			 * to approximate the results.
510
			 */
511
			if (thread == kgdb_info[i].task)
512
				local_debuggerinfo = kgdb_info[i].debuggerinfo;
513
		}
514
	}
515

516
	/*
517
	 * All threads that don't have debuggerinfo should be
518
	 * in schedule() sleeping, since all other CPUs
519
	 * are in kgdb_wait, and thus have debuggerinfo.
520
	 */
521
	if (local_debuggerinfo) {
522
		pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
523
	} else {
524
		/*
525
		 * Pull stuff saved during switch_to; nothing
526
		 * else is accessible (or even particularly
527
		 * relevant).
528
		 *
529
		 * This should be enough for a stack trace.
530
		 */
531
		sleeping_thread_to_gdb_regs(gdb_regs, thread);
532
	}
533
}
534

535
/* Handle the 'g' get registers request */
536
static void gdb_cmd_getregs(struct kgdb_state *ks)
537
{
538
	gdb_get_regs_helper(ks);
539
	kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
540
}
541

542
/* Handle the 'G' set registers request */
543
static void gdb_cmd_setregs(struct kgdb_state *ks)
544
{
545
	kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
546

547
	if (kgdb_usethread && kgdb_usethread != current) {
548
		error_packet(remcom_out_buffer, -EINVAL);
549
	} else {
550
		gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
551
		strscpy(remcom_out_buffer, "OK");
552
	}
553
}
554

555
/* Handle the 'm' memory read bytes */
556
static void gdb_cmd_memread(struct kgdb_state *ks)
557
{
558
	char *ptr = &remcom_in_buffer[1];
559
	unsigned long length;
560
	unsigned long addr;
561
	char *err;
562

563
	if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
564
					kgdb_hex2long(&ptr, &length) > 0) {
565
		err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
566
		if (!err)
567
			error_packet(remcom_out_buffer, -EINVAL);
568
	} else {
569
		error_packet(remcom_out_buffer, -EINVAL);
570
	}
571
}
572

573
/* Handle the 'M' memory write bytes */
574
static void gdb_cmd_memwrite(struct kgdb_state *ks)
575
{
576
	int err = write_mem_msg(0);
577

578
	if (err)
579
		error_packet(remcom_out_buffer, err);
580
	else
581
		strscpy(remcom_out_buffer, "OK");
582
}
583

584
#if DBG_MAX_REG_NUM > 0
585
static char *gdb_hex_reg_helper(int regnum, char *out)
586
{
587
	int i;
588
	int offset = 0;
589

590
	for (i = 0; i < regnum; i++)
591
		offset += dbg_reg_def[i].size;
592
	return kgdb_mem2hex((char *)gdb_regs + offset, out,
593
			    dbg_reg_def[i].size);
594
}
595

596
/* Handle the 'p' individual register get */
597
static void gdb_cmd_reg_get(struct kgdb_state *ks)
598
{
599
	unsigned long regnum;
600
	char *ptr = &remcom_in_buffer[1];
601

602
	kgdb_hex2long(&ptr, &regnum);
603
	if (regnum >= DBG_MAX_REG_NUM) {
604
		error_packet(remcom_out_buffer, -EINVAL);
605
		return;
606
	}
607
	gdb_get_regs_helper(ks);
608
	gdb_hex_reg_helper(regnum, remcom_out_buffer);
609
}
610

611
/* Handle the 'P' individual register set */
612
static void gdb_cmd_reg_set(struct kgdb_state *ks)
613
{
614
	unsigned long regnum;
615
	char *ptr = &remcom_in_buffer[1];
616
	int i = 0;
617

618
	kgdb_hex2long(&ptr, &regnum);
619
	if (*ptr++ != '=' ||
620
	    !(!kgdb_usethread || kgdb_usethread == current) ||
621
	    !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
622
		error_packet(remcom_out_buffer, -EINVAL);
623
		return;
624
	}
625
	memset(gdb_regs, 0, sizeof(gdb_regs));
626
	while (i < sizeof(gdb_regs) * 2)
627
		if (hex_to_bin(ptr[i]) >= 0)
628
			i++;
629
		else
630
			break;
631
	i = i / 2;
632
	kgdb_hex2mem(ptr, (char *)gdb_regs, i);
633
	dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
634
	strscpy(remcom_out_buffer, "OK");
635
}
636
#endif /* DBG_MAX_REG_NUM > 0 */
637

638
/* Handle the 'X' memory binary write bytes */
639
static void gdb_cmd_binwrite(struct kgdb_state *ks)
640
{
641
	int err = write_mem_msg(1);
642

643
	if (err)
644
		error_packet(remcom_out_buffer, err);
645
	else
646
		strscpy(remcom_out_buffer, "OK");
647
}
648

649
/* Handle the 'D' or 'k', detach or kill packets */
650
static void gdb_cmd_detachkill(struct kgdb_state *ks)
651
{
652
	int error;
653

654
	/* The detach case */
655
	if (remcom_in_buffer[0] == 'D') {
656
		error = dbg_remove_all_break();
657
		if (error < 0) {
658
			error_packet(remcom_out_buffer, error);
659
		} else {
660
			strscpy(remcom_out_buffer, "OK");
661
			kgdb_connected = 0;
662
		}
663
		put_packet(remcom_out_buffer);
664
	} else {
665
		/*
666
		 * Assume the kill case, with no exit code checking,
667
		 * trying to force detach the debugger:
668
		 */
669
		dbg_remove_all_break();
670
		kgdb_connected = 0;
671
	}
672
}
673

674
/* Handle the 'R' reboot packets */
675
static int gdb_cmd_reboot(struct kgdb_state *ks)
676
{
677
	/* For now, only honor R0 */
678
	if (strcmp(remcom_in_buffer, "R0") == 0) {
679
		printk(KERN_CRIT "Executing emergency reboot\n");
680
		strscpy(remcom_out_buffer, "OK");
681
		put_packet(remcom_out_buffer);
682

683
		/*
684
		 * Execution should not return from
685
		 * machine_emergency_restart()
686
		 */
687
		machine_emergency_restart();
688
		kgdb_connected = 0;
689

690
		return 1;
691
	}
692
	return 0;
693
}
694

695
/* Handle the 'q' query packets */
696
static void gdb_cmd_query(struct kgdb_state *ks)
697
{
698
	struct task_struct *g;
699
	struct task_struct *p;
700
	unsigned char thref[BUF_THREAD_ID_SIZE];
701
	char *ptr;
702
	int i;
703
	int cpu;
704
	int finished = 0;
705

706
	switch (remcom_in_buffer[1]) {
707
	case 's':
708
	case 'f':
709
		if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
710
			break;
711

712
		i = 0;
713
		remcom_out_buffer[0] = 'm';
714
		ptr = remcom_out_buffer + 1;
715
		if (remcom_in_buffer[1] == 'f') {
716
			/* Each cpu is a shadow thread */
717
			for_each_online_cpu(cpu) {
718
				ks->thr_query = 0;
719
				int_to_threadref(thref, -cpu - 2);
720
				ptr = pack_threadid(ptr, thref);
721
				*(ptr++) = ',';
722
				i++;
723
			}
724
		}
725

726
		for_each_process_thread(g, p) {
727
			if (i >= ks->thr_query && !finished) {
728
				int_to_threadref(thref, p->pid);
729
				ptr = pack_threadid(ptr, thref);
730
				*(ptr++) = ',';
731
				ks->thr_query++;
732
				if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
733
					finished = 1;
734
			}
735
			i++;
736
		}
737

738
		*(--ptr) = '\0';
739
		break;
740

741
	case 'C':
742
		/* Current thread id */
743
		strscpy(remcom_out_buffer, "QC");
744
		ks->threadid = shadow_pid(current->pid);
745
		int_to_threadref(thref, ks->threadid);
746
		pack_threadid(remcom_out_buffer + 2, thref);
747
		break;
748
	case 'T':
749
		if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
750
			break;
751

752
		ks->threadid = 0;
753
		ptr = remcom_in_buffer + 17;
754
		kgdb_hex2long(&ptr, &ks->threadid);
755
		if (!getthread(ks->linux_regs, ks->threadid)) {
756
			error_packet(remcom_out_buffer, -EINVAL);
757
			break;
758
		}
759
		if ((int)ks->threadid > 0) {
760
			kgdb_mem2hex(getthread(ks->linux_regs,
761
					ks->threadid)->comm,
762
					remcom_out_buffer, 16);
763
		} else {
764
			static char tmpstr[23 + BUF_THREAD_ID_SIZE];
765

766
			sprintf(tmpstr, "shadowCPU%d",
767
					(int)(-ks->threadid - 2));
768
			kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
769
		}
770
		break;
771
#ifdef CONFIG_KGDB_KDB
772
	case 'R':
773
		if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
774
			int len = strlen(remcom_in_buffer + 6);
775

776
			if ((len % 2) != 0) {
777
				strscpy(remcom_out_buffer, "E01");
778
				break;
779
			}
780
			kgdb_hex2mem(remcom_in_buffer + 6,
781
				     remcom_out_buffer, len);
782
			len = len / 2;
783
			remcom_out_buffer[len++] = 0;
784

785
			kdb_common_init_state(ks);
786
			kdb_parse(remcom_out_buffer);
787
			kdb_common_deinit_state();
788

789
			strscpy(remcom_out_buffer, "OK");
790
		}
791
		break;
792
#endif
793
#ifdef CONFIG_HAVE_ARCH_KGDB_QXFER_PKT
794
	case 'S':
795
		if (!strncmp(remcom_in_buffer, "qSupported:", 11))
796
			strscpy(remcom_out_buffer, kgdb_arch_gdb_stub_feature);
797
		break;
798
	case 'X':
799
		if (!strncmp(remcom_in_buffer, "qXfer:", 6))
800
			kgdb_arch_handle_qxfer_pkt(remcom_in_buffer,
801
						   remcom_out_buffer);
802
		break;
803
#endif
804
	default:
805
		break;
806
	}
807
}
808

809
/* Handle the 'H' task query packets */
810
static void gdb_cmd_task(struct kgdb_state *ks)
811
{
812
	struct task_struct *thread;
813
	char *ptr;
814

815
	switch (remcom_in_buffer[1]) {
816
	case 'g':
817
		ptr = &remcom_in_buffer[2];
818
		kgdb_hex2long(&ptr, &ks->threadid);
819
		thread = getthread(ks->linux_regs, ks->threadid);
820
		if (!thread && ks->threadid > 0) {
821
			error_packet(remcom_out_buffer, -EINVAL);
822
			break;
823
		}
824
		kgdb_usethread = thread;
825
		ks->kgdb_usethreadid = ks->threadid;
826
		strscpy(remcom_out_buffer, "OK");
827
		break;
828
	case 'c':
829
		ptr = &remcom_in_buffer[2];
830
		kgdb_hex2long(&ptr, &ks->threadid);
831
		if (!ks->threadid) {
832
			kgdb_contthread = NULL;
833
		} else {
834
			thread = getthread(ks->linux_regs, ks->threadid);
835
			if (!thread && ks->threadid > 0) {
836
				error_packet(remcom_out_buffer, -EINVAL);
837
				break;
838
			}
839
			kgdb_contthread = thread;
840
		}
841
		strscpy(remcom_out_buffer, "OK");
842
		break;
843
	}
844
}
845

846
/* Handle the 'T' thread query packets */
847
static void gdb_cmd_thread(struct kgdb_state *ks)
848
{
849
	char *ptr = &remcom_in_buffer[1];
850
	struct task_struct *thread;
851

852
	kgdb_hex2long(&ptr, &ks->threadid);
853
	thread = getthread(ks->linux_regs, ks->threadid);
854
	if (thread)
855
		strscpy(remcom_out_buffer, "OK");
856
	else
857
		error_packet(remcom_out_buffer, -EINVAL);
858
}
859

860
/* Handle the 'z' or 'Z' breakpoint remove or set packets */
861
static void gdb_cmd_break(struct kgdb_state *ks)
862
{
863
	/*
864
	 * Since GDB-5.3, it's been drafted that '0' is a software
865
	 * breakpoint, '1' is a hardware breakpoint, so let's do that.
866
	 */
867
	char *bpt_type = &remcom_in_buffer[1];
868
	char *ptr = &remcom_in_buffer[2];
869
	unsigned long addr;
870
	unsigned long length;
871
	int error = 0;
872

873
	if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
874
		/* Unsupported */
875
		if (*bpt_type > '4')
876
			return;
877
	} else {
878
		if (*bpt_type != '0' && *bpt_type != '1')
879
			/* Unsupported. */
880
			return;
881
	}
882

883
	/*
884
	 * Test if this is a hardware breakpoint, and
885
	 * if we support it:
886
	 */
887
	if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
888
		/* Unsupported. */
889
		return;
890

891
	if (*(ptr++) != ',') {
892
		error_packet(remcom_out_buffer, -EINVAL);
893
		return;
894
	}
895
	if (!kgdb_hex2long(&ptr, &addr)) {
896
		error_packet(remcom_out_buffer, -EINVAL);
897
		return;
898
	}
899
	if (*(ptr++) != ',' ||
900
		!kgdb_hex2long(&ptr, &length)) {
901
		error_packet(remcom_out_buffer, -EINVAL);
902
		return;
903
	}
904

905
	if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
906
		error = dbg_set_sw_break(addr);
907
	else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
908
		error = dbg_remove_sw_break(addr);
909
	else if (remcom_in_buffer[0] == 'Z')
910
		error = arch_kgdb_ops.set_hw_breakpoint(addr,
911
			(int)length, *bpt_type - '0');
912
	else if (remcom_in_buffer[0] == 'z')
913
		error = arch_kgdb_ops.remove_hw_breakpoint(addr,
914
			(int) length, *bpt_type - '0');
915

916
	if (error == 0)
917
		strscpy(remcom_out_buffer, "OK");
918
	else
919
		error_packet(remcom_out_buffer, error);
920
}
921

922
/* Handle the 'C' signal / exception passing packets */
923
static int gdb_cmd_exception_pass(struct kgdb_state *ks)
924
{
925
	/* C09 == pass exception
926
	 * C15 == detach kgdb, pass exception
927
	 */
928
	if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
929

930
		ks->pass_exception = 1;
931
		remcom_in_buffer[0] = 'c';
932

933
	} else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
934

935
		ks->pass_exception = 1;
936
		remcom_in_buffer[0] = 'D';
937
		dbg_remove_all_break();
938
		kgdb_connected = 0;
939
		return 1;
940

941
	} else {
942
		gdbstub_msg_write("KGDB only knows signal 9 (pass)"
943
			" and 15 (pass and disconnect)\n"
944
			"Executing a continue without signal passing\n", 0);
945
		remcom_in_buffer[0] = 'c';
946
	}
947

948
	/* Indicate fall through */
949
	return -1;
950
}
951

952
/*
953
 * This function performs all gdbserial command processing
954
 */
955
int gdb_serial_stub(struct kgdb_state *ks)
956
{
957
	int error = 0;
958
	int tmp;
959

960
	/* Initialize comm buffer and globals. */
961
	memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
962
	kgdb_usethread = kgdb_info[ks->cpu].task;
963
	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
964
	ks->pass_exception = 0;
965

966
	if (kgdb_connected) {
967
		unsigned char thref[BUF_THREAD_ID_SIZE];
968
		char *ptr;
969

970
		/* Reply to host that an exception has occurred */
971
		ptr = remcom_out_buffer;
972
		*ptr++ = 'T';
973
		ptr = hex_byte_pack(ptr, ks->signo);
974
		ptr += strlen(strcpy(ptr, "thread:"));
975
		int_to_threadref(thref, shadow_pid(current->pid));
976
		ptr = pack_threadid(ptr, thref);
977
		*ptr++ = ';';
978
		put_packet(remcom_out_buffer);
979
	}
980

981
	while (1) {
982
		error = 0;
983

984
		/* Clear the out buffer. */
985
		memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
986

987
		get_packet(remcom_in_buffer);
988

989
		switch (remcom_in_buffer[0]) {
990
		case '?': /* gdbserial status */
991
			gdb_cmd_status(ks);
992
			break;
993
		case 'g': /* return the value of the CPU registers */
994
			gdb_cmd_getregs(ks);
995
			break;
996
		case 'G': /* set the value of the CPU registers - return OK */
997
			gdb_cmd_setregs(ks);
998
			break;
999
		case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
1000
			gdb_cmd_memread(ks);
1001
			break;
1002
		case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1003
			gdb_cmd_memwrite(ks);
1004
			break;
1005
#if DBG_MAX_REG_NUM > 0
1006
		case 'p': /* pXX Return gdb register XX (in hex) */
1007
			gdb_cmd_reg_get(ks);
1008
			break;
1009
		case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
1010
			gdb_cmd_reg_set(ks);
1011
			break;
1012
#endif /* DBG_MAX_REG_NUM > 0 */
1013
		case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1014
			gdb_cmd_binwrite(ks);
1015
			break;
1016
			/* kill or detach. KGDB should treat this like a
1017
			 * continue.
1018
			 */
1019
		case 'D': /* Debugger detach */
1020
		case 'k': /* Debugger detach via kill */
1021
			gdb_cmd_detachkill(ks);
1022
			goto default_handle;
1023
		case 'R': /* Reboot */
1024
			if (gdb_cmd_reboot(ks))
1025
				goto default_handle;
1026
			break;
1027
		case 'q': /* query command */
1028
			gdb_cmd_query(ks);
1029
			break;
1030
		case 'H': /* task related */
1031
			gdb_cmd_task(ks);
1032
			break;
1033
		case 'T': /* Query thread status */
1034
			gdb_cmd_thread(ks);
1035
			break;
1036
		case 'z': /* Break point remove */
1037
		case 'Z': /* Break point set */
1038
			gdb_cmd_break(ks);
1039
			break;
1040
#ifdef CONFIG_KGDB_KDB
1041
		case '3': /* Escape into back into kdb */
1042
			if (remcom_in_buffer[1] == '\0') {
1043
				gdb_cmd_detachkill(ks);
1044
				return DBG_PASS_EVENT;
1045
			}
1046
			fallthrough;
1047
#endif
1048
		case 'C': /* Exception passing */
1049
			tmp = gdb_cmd_exception_pass(ks);
1050
			if (tmp > 0)
1051
				goto default_handle;
1052
			if (tmp == 0)
1053
				break;
1054
			fallthrough;	/* on tmp < 0 */
1055
		case 'c': /* Continue packet */
1056
		case 's': /* Single step packet */
1057
			if (kgdb_contthread && kgdb_contthread != current) {
1058
				/* Can't switch threads in kgdb */
1059
				error_packet(remcom_out_buffer, -EINVAL);
1060
				break;
1061
			}
1062
			fallthrough;	/* to default processing */
1063
		default:
1064
default_handle:
1065
			error = kgdb_arch_handle_exception(ks->ex_vector,
1066
						ks->signo,
1067
						ks->err_code,
1068
						remcom_in_buffer,
1069
						remcom_out_buffer,
1070
						ks->linux_regs);
1071
			/*
1072
			 * Leave cmd processing on error, detach,
1073
			 * kill, continue, or single step.
1074
			 */
1075
			if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1076
			    remcom_in_buffer[0] == 'k') {
1077
				error = 0;
1078
				goto kgdb_exit;
1079
			}
1080

1081
		}
1082

1083
		/* reply to the request */
1084
		put_packet(remcom_out_buffer);
1085
	}
1086

1087
kgdb_exit:
1088
	if (ks->pass_exception)
1089
		error = 1;
1090
	return error;
1091
}
1092

1093
int gdbstub_state(struct kgdb_state *ks, char *cmd)
1094
{
1095
	int error;
1096

1097
	switch (cmd[0]) {
1098
	case 'e':
1099
		error = kgdb_arch_handle_exception(ks->ex_vector,
1100
						   ks->signo,
1101
						   ks->err_code,
1102
						   remcom_in_buffer,
1103
						   remcom_out_buffer,
1104
						   ks->linux_regs);
1105
		return error;
1106
	case 's':
1107
	case 'c':
1108
		strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
1109
		return 0;
1110
	case '$':
1111
		strscpy(remcom_in_buffer, cmd, sizeof(remcom_in_buffer));
1112
		gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
1113
		gdbstub_prev_in_buf_pos = 0;
1114
		return 0;
1115
	}
1116
	dbg_io_ops->write_char('+');
1117
	put_packet(remcom_out_buffer);
1118
	return 0;
1119
}
1120

1121
/**
1122
 * gdbstub_exit - Send an exit message to GDB
1123
 * @status: The exit code to report.
1124
 */
1125
void gdbstub_exit(int status)
1126
{
1127
	unsigned char checksum, ch, buffer[3];
1128
	int loop;
1129

1130
	if (!kgdb_connected)
1131
		return;
1132
	kgdb_connected = 0;
1133

1134
	if (!dbg_io_ops || dbg_kdb_mode)
1135
		return;
1136

1137
	buffer[0] = 'W';
1138
	buffer[1] = hex_asc_hi(status);
1139
	buffer[2] = hex_asc_lo(status);
1140

1141
	dbg_io_ops->write_char('$');
1142
	checksum = 0;
1143

1144
	for (loop = 0; loop < 3; loop++) {
1145
		ch = buffer[loop];
1146
		checksum += ch;
1147
		dbg_io_ops->write_char(ch);
1148
	}
1149

1150
	dbg_io_ops->write_char('#');
1151
	dbg_io_ops->write_char(hex_asc_hi(checksum));
1152
	dbg_io_ops->write_char(hex_asc_lo(checksum));
1153

1154
	/* make sure the output is flushed, lest the bootloader clobber it */
1155
	if (dbg_io_ops->flush)
1156
		dbg_io_ops->flush();
1157
}
1158

1159