1/*
   2 * Kernel Debug Core
   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@ucw.cz>
  10 * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
  11 * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
  12 * Copyright (C) 2005-2009 Wind River Systems, Inc.
  13 * Copyright (C) 2007 MontaVista Software, Inc.
  14 * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  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
  31#include <linux/kernel.h>
  32#include <linux/sched/signal.h>
  33#include <linux/kgdb.h>
  34#include <linux/kdb.h>
  35#include <linux/serial_core.h>
  36#include <linux/reboot.h>
  37#include <linux/uaccess.h>
  38#include <asm/cacheflush.h>
  39#include <asm/unaligned.h>
  40#include "debug_core.h"
  41
  42#define KGDB_MAX_THREAD_QUERY 17
  43
  44/* Our I/O buffers. */
  45static char			remcom_in_buffer[BUFMAX];
  46static char			remcom_out_buffer[BUFMAX];
  47static int			gdbstub_use_prev_in_buf;
  48static int			gdbstub_prev_in_buf_pos;
  49
  50/* Storage for the registers, in GDB format. */
  51static unsigned long		gdb_regs[(NUMREGBYTES +
  52					sizeof(unsigned long) - 1) /
  53					sizeof(unsigned long)];
  54
  55/*
  56 * GDB remote protocol parser:
  57 */
  58
  59#ifdef CONFIG_KGDB_KDB
  60static int gdbstub_read_wait(void)
  61{
  62	int ret = -1;
  63	int i;
  64
  65	if (unlikely(gdbstub_use_prev_in_buf)) {
  66		if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
  67			return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
  68		else
  69			gdbstub_use_prev_in_buf = 0;
  70	}
  71
  72	/* poll any additional I/O interfaces that are defined */
  73	while (ret < 0)
  74		for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
  75			ret = kdb_poll_funcs[i]();
  76			if (ret > 0)
  77				break;
  78		}
  79	return ret;
  80}
  81#else
  82static int gdbstub_read_wait(void)
  83{
  84	int ret = dbg_io_ops->read_char();
  85	while (ret == NO_POLL_CHAR)
  86		ret = dbg_io_ops->read_char();
  87	return ret;
  88}
  89#endif
  90/* scan for the sequence $<data>#<checksum> */
  91static void get_packet(char *buffer)
  92{
  93	unsigned char checksum;
  94	unsigned char xmitcsum;
  95	int count;
  96	char ch;
  97
  98	do {
  99		/*
 100		 * Spin and wait around for the start character, ignore all
 101		 * other characters:
 102		 */
 103		while ((ch = (gdbstub_read_wait())) != '$')
 104			/* nothing */;
 105
 106		kgdb_connected = 1;
 107		checksum = 0;
 108		xmitcsum = -1;
 109
 110		count = 0;
 111
 112		/*
 113		 * now, read until a # or end of buffer is found:
 114		 */
 115		while (count < (BUFMAX - 1)) {
 116			ch = gdbstub_read_wait();
 117			if (ch == '#')
 118				break;
 119			checksum = checksum + ch;
 120			buffer[count] = ch;
 121			count = count + 1;
 122		}
 123
 124		if (ch == '#') {
 125			xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
 126			xmitcsum += hex_to_bin(gdbstub_read_wait());
 127
 128			if (checksum != xmitcsum)
 129				/* failed checksum */
 130				dbg_io_ops->write_char('-');
 131			else
 132				/* successful transfer */
 133				dbg_io_ops->write_char('+');
 134			if (dbg_io_ops->flush)
 135				dbg_io_ops->flush();
 136		}
 137		buffer[count] = 0;
 138	} while (checksum != xmitcsum);
 139}
 140
 141/*
 142 * Send the packet in buffer.
 143 * Check for gdb connection if asked for.
 144 */
 145static void put_packet(char *buffer)
 146{
 147	unsigned char checksum;
 148	int count;
 149	char ch;
 150
 151	/*
 152	 * $<packet info>#<checksum>.
 153	 */
 154	while (1) {
 155		dbg_io_ops->write_char('$');
 156		checksum = 0;
 157		count = 0;
 158
 159		while ((ch = buffer[count])) {
 160			dbg_io_ops->write_char(ch);
 161			checksum += ch;
 162			count++;
 163		}
 164
 165		dbg_io_ops->write_char('#');
 166		dbg_io_ops->write_char(hex_asc_hi(checksum));
 167		dbg_io_ops->write_char(hex_asc_lo(checksum));
 168		if (dbg_io_ops->flush)
 169			dbg_io_ops->flush();
 170
 171		/* Now see what we get in reply. */
 172		ch = gdbstub_read_wait();
 173
 174		if (ch == 3)
 175			ch = gdbstub_read_wait();
 176
 177		/* If we get an ACK, we are done. */
 178		if (ch == '+')
 179			return;
 180
 181		/*
 182		 * If we get the start of another packet, this means
 183		 * that GDB is attempting to reconnect.  We will NAK
 184		 * the packet being sent, and stop trying to send this
 185		 * packet.
 186		 */
 187		if (ch == '$') {
 188			dbg_io_ops->write_char('-');
 189			if (dbg_io_ops->flush)
 190				dbg_io_ops->flush();
 191			return;
 192		}
 193	}
 194}
 195
 196static char gdbmsgbuf[BUFMAX + 1];
 197
 198void gdbstub_msg_write(const char *s, int len)
 199{
 200	char *bufptr;
 201	int wcount;
 202	int i;
 203
 204	if (len == 0)
 205		len = strlen(s);
 206
 207	/* 'O'utput */
 208	gdbmsgbuf[0] = 'O';
 209
 210	/* Fill and send buffers... */
 211	while (len > 0) {
 212		bufptr = gdbmsgbuf + 1;
 213
 214		/* Calculate how many this time */
 215		if ((len << 1) > (BUFMAX - 2))
 216			wcount = (BUFMAX - 2) >> 1;
 217		else
 218			wcount = len;
 219
 220		/* Pack in hex chars */
 221		for (i = 0; i < wcount; i++)
 222			bufptr = hex_byte_pack(bufptr, s[i]);
 223		*bufptr = '\0';
 224
 225		/* Move up */
 226		s += wcount;
 227		len -= wcount;
 228
 229		/* Write packet */
 230		put_packet(gdbmsgbuf);
 231	}
 232}
 233
 234/*
 235 * Convert the memory pointed to by mem into hex, placing result in
 236 * buf.  Return a pointer to the last char put in buf (null). May
 237 * return an error.
 238 */
 239char *kgdb_mem2hex(char *mem, char *buf, int count)
 240{
 241	char *tmp;
 242	int err;
 243
 244	/*
 245	 * We use the upper half of buf as an intermediate buffer for the
 246	 * raw memory copy.  Hex conversion will work against this one.
 247	 */
 248	tmp = buf + count;
 249
 250	err = probe_kernel_read(tmp, mem, count);
 251	if (err)
 252		return NULL;
 253	while (count > 0) {
 254		buf = hex_byte_pack(buf, *tmp);
 255		tmp++;
 256		count--;
 257	}
 258	*buf = 0;
 259
 260	return buf;
 261}
 262
 263/*
 264 * Convert the hex array pointed to by buf into binary to be placed in
 265 * mem.  Return a pointer to the character AFTER the last byte
 266 * written.  May return an error.
 267 */
 268int kgdb_hex2mem(char *buf, char *mem, int count)
 269{
 270	char *tmp_raw;
 271	char *tmp_hex;
 272
 273	/*
 274	 * We use the upper half of buf as an intermediate buffer for the
 275	 * raw memory that is converted from hex.
 276	 */
 277	tmp_raw = buf + count * 2;
 278
 279	tmp_hex = tmp_raw - 1;
 280	while (tmp_hex >= buf) {
 281		tmp_raw--;
 282		*tmp_raw = hex_to_bin(*tmp_hex--);
 283		*tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
 284	}
 285
 286	return probe_kernel_write(mem, tmp_raw, count);
 287}
 288
 289/*
 290 * While we find nice hex chars, build a long_val.
 291 * Return number of chars processed.
 292 */
 293int kgdb_hex2long(char **ptr, unsigned long *long_val)
 294{
 295	int hex_val;
 296	int num = 0;
 297	int negate = 0;
 298
 299	*long_val = 0;
 300
 301	if (**ptr == '-') {
 302		negate = 1;
 303		(*ptr)++;
 304	}
 305	while (**ptr) {
 306		hex_val = hex_to_bin(**ptr);
 307		if (hex_val < 0)
 308			break;
 309
 310		*long_val = (*long_val << 4) | hex_val;
 311		num++;
 312		(*ptr)++;
 313	}
 314
 315	if (negate)
 316		*long_val = -*long_val;
 317
 318	return num;
 319}
 320
 321/*
 322 * Copy the binary array pointed to by buf into mem.  Fix $, #, and
 323 * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
 324 * The input buf is overwitten with the result to write to mem.
 325 */
 326static int kgdb_ebin2mem(char *buf, char *mem, int count)
 327{
 328	int size = 0;
 329	char *c = buf;
 330
 331	while (count-- > 0) {
 332		c[size] = *buf++;
 333		if (c[size] == 0x7d)
 334			c[size] = *buf++ ^ 0x20;
 335		size++;
 336	}
 337
 338	return probe_kernel_write(mem, c, size);
 339}
 340
 341#if DBG_MAX_REG_NUM > 0
 342void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 343{
 344	int i;
 345	int idx = 0;
 346	char *ptr = (char *)gdb_regs;
 347
 348	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
 349		dbg_get_reg(i, ptr + idx, regs);
 350		idx += dbg_reg_def[i].size;
 351	}
 352}
 353
 354void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 355{
 356	int i;
 357	int idx = 0;
 358	char *ptr = (char *)gdb_regs;
 359
 360	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
 361		dbg_set_reg(i, ptr + idx, regs);
 362		idx += dbg_reg_def[i].size;
 363	}
 364}
 365#endif /* DBG_MAX_REG_NUM > 0 */
 366
 367/* Write memory due to an 'M' or 'X' packet. */
 368static int write_mem_msg(int binary)
 369{
 370	char *ptr = &remcom_in_buffer[1];
 371	unsigned long addr;
 372	unsigned long length;
 373	int err;
 374
 375	if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
 376	    kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
 377		if (binary)
 378			err = kgdb_ebin2mem(ptr, (char *)addr, length);
 379		else
 380			err = kgdb_hex2mem(ptr, (char *)addr, length);
 381		if (err)
 382			return err;
 383		if (CACHE_FLUSH_IS_SAFE)
 384			flush_icache_range(addr, addr + length);
 385		return 0;
 386	}
 387
 388	return -EINVAL;
 389}
 390
 391static void error_packet(char *pkt, int error)
 392{
 393	error = -error;
 394	pkt[0] = 'E';
 395	pkt[1] = hex_asc[(error / 10)];
 396	pkt[2] = hex_asc[(error % 10)];
 397	pkt[3] = '\0';
 398}
 399
 400/*
 401 * Thread ID accessors. We represent a flat TID space to GDB, where
 402 * the per CPU idle threads (which under Linux all have PID 0) are
 403 * remapped to negative TIDs.
 404 */
 405
 406#define BUF_THREAD_ID_SIZE	8
 407
 408static char *pack_threadid(char *pkt, unsigned char *id)
 409{
 410	unsigned char *limit;
 411	int lzero = 1;
 412
 413	limit = id + (BUF_THREAD_ID_SIZE / 2);
 414	while (id < limit) {
 415		if (!lzero || *id != 0) {
 416			pkt = hex_byte_pack(pkt, *id);
 417			lzero = 0;
 418		}
 419		id++;
 420	}
 421
 422	if (lzero)
 423		pkt = hex_byte_pack(pkt, 0);
 424
 425	return pkt;
 426}
 427
 428static void int_to_threadref(unsigned char *id, int value)
 429{
 430	put_unaligned_be32(value, id);
 431}
 432
 433static struct task_struct *getthread(struct pt_regs *regs, int tid)
 434{
 435	/*
 436	 * Non-positive TIDs are remapped to the cpu shadow information
 437	 */
 438	if (tid == 0 || tid == -1)
 439		tid = -atomic_read(&kgdb_active) - 2;
 440	if (tid < -1 && tid > -NR_CPUS - 2) {
 441		if (kgdb_info[-tid - 2].task)
 442			return kgdb_info[-tid - 2].task;
 443		else
 444			return idle_task(-tid - 2);
 445	}
 446	if (tid <= 0) {
 447		printk(KERN_ERR "KGDB: Internal thread select error\n");
 448		dump_stack();
 449		return NULL;
 450	}
 451
 452	/*
 453	 * find_task_by_pid_ns() does not take the tasklist lock anymore
 454	 * but is nicely RCU locked - hence is a pretty resilient
 455	 * thing to use:
 456	 */
 457	return find_task_by_pid_ns(tid, &init_pid_ns);
 458}
 459
 460
 461/*
 462 * Remap normal tasks to their real PID,
 463 * CPU shadow threads are mapped to -CPU - 2
 464 */
 465static inline int shadow_pid(int realpid)
 466{
 467	if (realpid)
 468		return realpid;
 469
 470	return -raw_smp_processor_id() - 2;
 471}
 472
 473/*
 474 * All the functions that start with gdb_cmd are the various
 475 * operations to implement the handlers for the gdbserial protocol
 476 * where KGDB is communicating with an external debugger
 477 */
 478
 479/* Handle the '?' status packets */
 480static void gdb_cmd_status(struct kgdb_state *ks)
 481{
 482	/*
 483	 * We know that this packet is only sent
 484	 * during initial connect.  So to be safe,
 485	 * we clear out our breakpoints now in case
 486	 * GDB is reconnecting.
 487	 */
 488	dbg_remove_all_break();
 489
 490	remcom_out_buffer[0] = 'S';
 491	hex_byte_pack(&remcom_out_buffer[1], ks->signo);
 492}
 493
 494static void gdb_get_regs_helper(struct kgdb_state *ks)
 495{
 496	struct task_struct *thread;
 497	void *local_debuggerinfo;
 498	int i;
 499
 500	thread = kgdb_usethread;
 501	if (!thread) {
 502		thread = kgdb_info[ks->cpu].task;
 503		local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
 504	} else {
 505		local_debuggerinfo = NULL;
 506		for_each_online_cpu(i) {
 507			/*
 508			 * Try to find the task on some other
 509			 * or possibly this node if we do not
 510			 * find the matching task then we try
 511			 * to approximate the results.
 512			 */
 513			if (thread == kgdb_info[i].task)
 514				local_debuggerinfo = kgdb_info[i].debuggerinfo;
 515		}
 516	}
 517
 518	/*
 519	 * All threads that don't have debuggerinfo should be
 520	 * in schedule() sleeping, since all other CPUs
 521	 * are in kgdb_wait, and thus have debuggerinfo.
 522	 */
 523	if (local_debuggerinfo) {
 524		pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
 525	} else {
 526		/*
 527		 * Pull stuff saved during switch_to; nothing
 528		 * else is accessible (or even particularly
 529		 * relevant).
 530		 *
 531		 * This should be enough for a stack trace.
 532		 */
 533		sleeping_thread_to_gdb_regs(gdb_regs, thread);
 534	}
 535}
 536
 537/* Handle the 'g' get registers request */
 538static void gdb_cmd_getregs(struct kgdb_state *ks)
 539{
 540	gdb_get_regs_helper(ks);
 541	kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 542}
 543
 544/* Handle the 'G' set registers request */
 545static void gdb_cmd_setregs(struct kgdb_state *ks)
 546{
 547	kgdb_hex2mem(&remcom_in_buffer[1], (char *)gdb_regs, NUMREGBYTES);
 548
 549	if (kgdb_usethread && kgdb_usethread != current) {
 550		error_packet(remcom_out_buffer, -EINVAL);
 551	} else {
 552		gdb_regs_to_pt_regs(gdb_regs, ks->linux_regs);
 553		strcpy(remcom_out_buffer, "OK");
 554	}
 555}
 556
 557/* Handle the 'm' memory read bytes */
 558static void gdb_cmd_memread(struct kgdb_state *ks)
 559{
 560	char *ptr = &remcom_in_buffer[1];
 561	unsigned long length;
 562	unsigned long addr;
 563	char *err;
 564
 565	if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
 566					kgdb_hex2long(&ptr, &length) > 0) {
 567		err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
 568		if (!err)
 569			error_packet(remcom_out_buffer, -EINVAL);
 570	} else {
 571		error_packet(remcom_out_buffer, -EINVAL);
 572	}
 573}
 574
 575/* Handle the 'M' memory write bytes */
 576static void gdb_cmd_memwrite(struct kgdb_state *ks)
 577{
 578	int err = write_mem_msg(0);
 579
 580	if (err)
 581		error_packet(remcom_out_buffer, err);
 582	else
 583		strcpy(remcom_out_buffer, "OK");
 584}
 585
 586#if DBG_MAX_REG_NUM > 0
 587static char *gdb_hex_reg_helper(int regnum, char *out)
 588{
 589	int i;
 590	int offset = 0;
 591
 592	for (i = 0; i < regnum; i++)
 593		offset += dbg_reg_def[i].size;
 594	return kgdb_mem2hex((char *)gdb_regs + offset, out,
 595			    dbg_reg_def[i].size);
 596}
 597
 598/* Handle the 'p' individual regster get */
 599static void gdb_cmd_reg_get(struct kgdb_state *ks)
 600{
 601	unsigned long regnum;
 602	char *ptr = &remcom_in_buffer[1];
 603
 604	kgdb_hex2long(&ptr, &regnum);
 605	if (regnum >= DBG_MAX_REG_NUM) {
 606		error_packet(remcom_out_buffer, -EINVAL);
 607		return;
 608	}
 609	gdb_get_regs_helper(ks);
 610	gdb_hex_reg_helper(regnum, remcom_out_buffer);
 611}
 612
 613/* Handle the 'P' individual regster set */
 614static void gdb_cmd_reg_set(struct kgdb_state *ks)
 615{
 616	unsigned long regnum;
 617	char *ptr = &remcom_in_buffer[1];
 618	int i = 0;
 619
 620	kgdb_hex2long(&ptr, &regnum);
 621	if (*ptr++ != '=' ||
 622	    !(!kgdb_usethread || kgdb_usethread == current) ||
 623	    !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
 624		error_packet(remcom_out_buffer, -EINVAL);
 625		return;
 626	}
 627	memset(gdb_regs, 0, sizeof(gdb_regs));
 628	while (i < sizeof(gdb_regs) * 2)
 629		if (hex_to_bin(ptr[i]) >= 0)
 630			i++;
 631		else
 632			break;
 633	i = i / 2;
 634	kgdb_hex2mem(ptr, (char *)gdb_regs, i);
 635	dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
 636	strcpy(remcom_out_buffer, "OK");
 637}
 638#endif /* DBG_MAX_REG_NUM > 0 */
 639
 640/* Handle the 'X' memory binary write bytes */
 641static void gdb_cmd_binwrite(struct kgdb_state *ks)
 642{
 643	int err = write_mem_msg(1);
 644
 645	if (err)
 646		error_packet(remcom_out_buffer, err);
 647	else
 648		strcpy(remcom_out_buffer, "OK");
 649}
 650
 651/* Handle the 'D' or 'k', detach or kill packets */
 652static void gdb_cmd_detachkill(struct kgdb_state *ks)
 653{
 654	int error;
 655
 656	/* The detach case */
 657	if (remcom_in_buffer[0] == 'D') {
 658		error = dbg_remove_all_break();
 659		if (error < 0) {
 660			error_packet(remcom_out_buffer, error);
 661		} else {
 662			strcpy(remcom_out_buffer, "OK");
 663			kgdb_connected = 0;
 664		}
 665		put_packet(remcom_out_buffer);
 666	} else {
 667		/*
 668		 * Assume the kill case, with no exit code checking,
 669		 * trying to force detach the debugger:
 670		 */
 671		dbg_remove_all_break();
 672		kgdb_connected = 0;
 673	}
 674}
 675
 676/* Handle the 'R' reboot packets */
 677static int gdb_cmd_reboot(struct kgdb_state *ks)
 678{
 679	/* For now, only honor R0 */
 680	if (strcmp(remcom_in_buffer, "R0") == 0) {
 681		printk(KERN_CRIT "Executing emergency reboot\n");
 682		strcpy(remcom_out_buffer, "OK");
 683		put_packet(remcom_out_buffer);
 684
 685		/*
 686		 * Execution should not return from
 687		 * machine_emergency_restart()
 688		 */
 689		machine_emergency_restart();
 690		kgdb_connected = 0;
 691
 692		return 1;
 693	}
 694	return 0;
 695}
 696
 697/* Handle the 'q' query packets */
 698static void gdb_cmd_query(struct kgdb_state *ks)
 699{
 700	struct task_struct *g;
 701	struct task_struct *p;
 702	unsigned char thref[BUF_THREAD_ID_SIZE];
 703	char *ptr;
 704	int i;
 705	int cpu;
 706	int finished = 0;
 707
 708	switch (remcom_in_buffer[1]) {
 709	case 's':
 710	case 'f':
 711		if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
 712			break;
 713
 714		i = 0;
 715		remcom_out_buffer[0] = 'm';
 716		ptr = remcom_out_buffer + 1;
 717		if (remcom_in_buffer[1] == 'f') {
 718			/* Each cpu is a shadow thread */
 719			for_each_online_cpu(cpu) {
 720				ks->thr_query = 0;
 721				int_to_threadref(thref, -cpu - 2);
 722				ptr = pack_threadid(ptr, thref);
 723				*(ptr++) = ',';
 724				i++;
 725			}
 726		}
 727
 728		do_each_thread(g, p) {
 729			if (i >= ks->thr_query && !finished) {
 730				int_to_threadref(thref, p->pid);
 731				ptr = pack_threadid(ptr, thref);
 732				*(ptr++) = ',';
 733				ks->thr_query++;
 734				if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
 735					finished = 1;
 736			}
 737			i++;
 738		} while_each_thread(g, p);
 739
 740		*(--ptr) = '\0';
 741		break;
 742
 743	case 'C':
 744		/* Current thread id */
 745		strcpy(remcom_out_buffer, "QC");
 746		ks->threadid = shadow_pid(current->pid);
 747		int_to_threadref(thref, ks->threadid);
 748		pack_threadid(remcom_out_buffer + 2, thref);
 749		break;
 750	case 'T':
 751		if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
 752			break;
 753
 754		ks->threadid = 0;
 755		ptr = remcom_in_buffer + 17;
 756		kgdb_hex2long(&ptr, &ks->threadid);
 757		if (!getthread(ks->linux_regs, ks->threadid)) {
 758			error_packet(remcom_out_buffer, -EINVAL);
 759			break;
 760		}
 761		if ((int)ks->threadid > 0) {
 762			kgdb_mem2hex(getthread(ks->linux_regs,
 763					ks->threadid)->comm,
 764					remcom_out_buffer, 16);
 765		} else {
 766			static char tmpstr[23 + BUF_THREAD_ID_SIZE];
 767
 768			sprintf(tmpstr, "shadowCPU%d",
 769					(int)(-ks->threadid - 2));
 770			kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
 771		}
 772		break;
 773#ifdef CONFIG_KGDB_KDB
 774	case 'R':
 775		if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
 776			int len = strlen(remcom_in_buffer + 6);
 777
 778			if ((len % 2) != 0) {
 779				strcpy(remcom_out_buffer, "E01");
 780				break;
 781			}
 782			kgdb_hex2mem(remcom_in_buffer + 6,
 783				     remcom_out_buffer, len);
 784			len = len / 2;
 785			remcom_out_buffer[len++] = 0;
 786
 787			kdb_common_init_state(ks);
 788			kdb_parse(remcom_out_buffer);
 789			kdb_common_deinit_state();
 790
 791			strcpy(remcom_out_buffer, "OK");
 792		}
 793		break;
 794#endif
 795	}
 796}
 797
 798/* Handle the 'H' task query packets */
 799static void gdb_cmd_task(struct kgdb_state *ks)
 800{
 801	struct task_struct *thread;
 802	char *ptr;
 803
 804	switch (remcom_in_buffer[1]) {
 805	case 'g':
 806		ptr = &remcom_in_buffer[2];
 807		kgdb_hex2long(&ptr, &ks->threadid);
 808		thread = getthread(ks->linux_regs, ks->threadid);
 809		if (!thread && ks->threadid > 0) {
 810			error_packet(remcom_out_buffer, -EINVAL);
 811			break;
 812		}
 813		kgdb_usethread = thread;
 814		ks->kgdb_usethreadid = ks->threadid;
 815		strcpy(remcom_out_buffer, "OK");
 816		break;
 817	case 'c':
 818		ptr = &remcom_in_buffer[2];
 819		kgdb_hex2long(&ptr, &ks->threadid);
 820		if (!ks->threadid) {
 821			kgdb_contthread = NULL;
 822		} else {
 823			thread = getthread(ks->linux_regs, ks->threadid);
 824			if (!thread && ks->threadid > 0) {
 825				error_packet(remcom_out_buffer, -EINVAL);
 826				break;
 827			}
 828			kgdb_contthread = thread;
 829		}
 830		strcpy(remcom_out_buffer, "OK");
 831		break;
 832	}
 833}
 834
 835/* Handle the 'T' thread query packets */
 836static void gdb_cmd_thread(struct kgdb_state *ks)
 837{
 838	char *ptr = &remcom_in_buffer[1];
 839	struct task_struct *thread;
 840
 841	kgdb_hex2long(&ptr, &ks->threadid);
 842	thread = getthread(ks->linux_regs, ks->threadid);
 843	if (thread)
 844		strcpy(remcom_out_buffer, "OK");
 845	else
 846		error_packet(remcom_out_buffer, -EINVAL);
 847}
 848
 849/* Handle the 'z' or 'Z' breakpoint remove or set packets */
 850static void gdb_cmd_break(struct kgdb_state *ks)
 851{
 852	/*
 853	 * Since GDB-5.3, it's been drafted that '0' is a software
 854	 * breakpoint, '1' is a hardware breakpoint, so let's do that.
 855	 */
 856	char *bpt_type = &remcom_in_buffer[1];
 857	char *ptr = &remcom_in_buffer[2];
 858	unsigned long addr;
 859	unsigned long length;
 860	int error = 0;
 861
 862	if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
 863		/* Unsupported */
 864		if (*bpt_type > '4')
 865			return;
 866	} else {
 867		if (*bpt_type != '0' && *bpt_type != '1')
 868			/* Unsupported. */
 869			return;
 870	}
 871
 872	/*
 873	 * Test if this is a hardware breakpoint, and
 874	 * if we support it:
 875	 */
 876	if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
 877		/* Unsupported. */
 878		return;
 879
 880	if (*(ptr++) != ',') {
 881		error_packet(remcom_out_buffer, -EINVAL);
 882		return;
 883	}
 884	if (!kgdb_hex2long(&ptr, &addr)) {
 885		error_packet(remcom_out_buffer, -EINVAL);
 886		return;
 887	}
 888	if (*(ptr++) != ',' ||
 889		!kgdb_hex2long(&ptr, &length)) {
 890		error_packet(remcom_out_buffer, -EINVAL);
 891		return;
 892	}
 893
 894	if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
 895		error = dbg_set_sw_break(addr);
 896	else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
 897		error = dbg_remove_sw_break(addr);
 898	else if (remcom_in_buffer[0] == 'Z')
 899		error = arch_kgdb_ops.set_hw_breakpoint(addr,
 900			(int)length, *bpt_type - '0');
 901	else if (remcom_in_buffer[0] == 'z')
 902		error = arch_kgdb_ops.remove_hw_breakpoint(addr,
 903			(int) length, *bpt_type - '0');
 904
 905	if (error == 0)
 906		strcpy(remcom_out_buffer, "OK");
 907	else
 908		error_packet(remcom_out_buffer, error);
 909}
 910
 911/* Handle the 'C' signal / exception passing packets */
 912static int gdb_cmd_exception_pass(struct kgdb_state *ks)
 913{
 914	/* C09 == pass exception
 915	 * C15 == detach kgdb, pass exception
 916	 */
 917	if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
 918
 919		ks->pass_exception = 1;
 920		remcom_in_buffer[0] = 'c';
 921
 922	} else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
 923
 924		ks->pass_exception = 1;
 925		remcom_in_buffer[0] = 'D';
 926		dbg_remove_all_break();
 927		kgdb_connected = 0;
 928		return 1;
 929
 930	} else {
 931		gdbstub_msg_write("KGDB only knows signal 9 (pass)"
 932			" and 15 (pass and disconnect)\n"
 933			"Executing a continue without signal passing\n", 0);
 934		remcom_in_buffer[0] = 'c';
 935	}
 936
 937	/* Indicate fall through */
 938	return -1;
 939}
 940
 941/*
 942 * This function performs all gdbserial command procesing
 943 */
 944int gdb_serial_stub(struct kgdb_state *ks)
 945{
 946	int error = 0;
 947	int tmp;
 948
 949	/* Initialize comm buffer and globals. */
 950	memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
 951	kgdb_usethread = kgdb_info[ks->cpu].task;
 952	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
 953	ks->pass_exception = 0;
 954
 955	if (kgdb_connected) {
 956		unsigned char thref[BUF_THREAD_ID_SIZE];
 957		char *ptr;
 958
 959		/* Reply to host that an exception has occurred */
 960		ptr = remcom_out_buffer;
 961		*ptr++ = 'T';
 962		ptr = hex_byte_pack(ptr, ks->signo);
 963		ptr += strlen(strcpy(ptr, "thread:"));
 964		int_to_threadref(thref, shadow_pid(current->pid));
 965		ptr = pack_threadid(ptr, thref);
 966		*ptr++ = ';';
 967		put_packet(remcom_out_buffer);
 968	}
 969
 970	while (1) {
 971		error = 0;
 972
 973		/* Clear the out buffer. */
 974		memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
 975
 976		get_packet(remcom_in_buffer);
 977
 978		switch (remcom_in_buffer[0]) {
 979		case '?': /* gdbserial status */
 980			gdb_cmd_status(ks);
 981			break;
 982		case 'g': /* return the value of the CPU registers */
 983			gdb_cmd_getregs(ks);
 984			break;
 985		case 'G': /* set the value of the CPU registers - return OK */
 986			gdb_cmd_setregs(ks);
 987			break;
 988		case 'm': /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
 989			gdb_cmd_memread(ks);
 990			break;
 991		case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
 992			gdb_cmd_memwrite(ks);
 993			break;
 994#if DBG_MAX_REG_NUM > 0
 995		case 'p': /* pXX Return gdb register XX (in hex) */
 996			gdb_cmd_reg_get(ks);
 997			break;
 998		case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
 999			gdb_cmd_reg_set(ks);
1000			break;
1001#endif /* DBG_MAX_REG_NUM > 0 */
1002		case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
1003			gdb_cmd_binwrite(ks);
1004			break;
1005			/* kill or detach. KGDB should treat this like a
1006			 * continue.
1007			 */
1008		case 'D': /* Debugger detach */
1009		case 'k': /* Debugger detach via kill */
1010			gdb_cmd_detachkill(ks);
1011			goto default_handle;
1012		case 'R': /* Reboot */
1013			if (gdb_cmd_reboot(ks))
1014				goto default_handle;
1015			break;
1016		case 'q': /* query command */
1017			gdb_cmd_query(ks);
1018			break;
1019		case 'H': /* task related */
1020			gdb_cmd_task(ks);
1021			break;
1022		case 'T': /* Query thread status */
1023			gdb_cmd_thread(ks);
1024			break;
1025		case 'z': /* Break point remove */
1026		case 'Z': /* Break point set */
1027			gdb_cmd_break(ks);
1028			break;
1029#ifdef CONFIG_KGDB_KDB
1030		case '3': /* Escape into back into kdb */
1031			if (remcom_in_buffer[1] == '\0') {
1032				gdb_cmd_detachkill(ks);
1033				return DBG_PASS_EVENT;
1034			}
1035#endif
 
1036		case 'C': /* Exception passing */
1037			tmp = gdb_cmd_exception_pass(ks);
1038			if (tmp > 0)
1039				goto default_handle;
1040			if (tmp == 0)
1041				break;
1042			/* Fall through on tmp < 0 */
1043		case 'c': /* Continue packet */
1044		case 's': /* Single step packet */
1045			if (kgdb_contthread && kgdb_contthread != current) {
1046				/* Can't switch threads in kgdb */
1047				error_packet(remcom_out_buffer, -EINVAL);
1048				break;
1049			}
1050			dbg_activate_sw_breakpoints();
1051			/* Fall through to default processing */
1052		default:
1053default_handle:
1054			error = kgdb_arch_handle_exception(ks->ex_vector,
1055						ks->signo,
1056						ks->err_code,
1057						remcom_in_buffer,
1058						remcom_out_buffer,
1059						ks->linux_regs);
1060			/*
1061			 * Leave cmd processing on error, detach,
1062			 * kill, continue, or single step.
1063			 */
1064			if (error >= 0 || remcom_in_buffer[0] == 'D' ||
1065			    remcom_in_buffer[0] == 'k') {
1066				error = 0;
1067				goto kgdb_exit;
1068			}
1069
1070		}
1071
1072		/* reply to the request */
1073		put_packet(remcom_out_buffer);
1074	}
1075
1076kgdb_exit:
1077	if (ks->pass_exception)
1078		error = 1;
1079	return error;
1080}
1081
1082int gdbstub_state(struct kgdb_state *ks, char *cmd)
1083{
1084	int error;
1085
1086	switch (cmd[0]) {
1087	case 'e':
1088		error = kgdb_arch_handle_exception(ks->ex_vector,
1089						   ks->signo,
1090						   ks->err_code,
1091						   remcom_in_buffer,
1092						   remcom_out_buffer,
1093						   ks->linux_regs);
1094		return error;
1095	case 's':
1096	case 'c':
1097		strcpy(remcom_in_buffer, cmd);
1098		return 0;
1099	case '$':
1100		strcpy(remcom_in_buffer, cmd);
1101		gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
1102		gdbstub_prev_in_buf_pos = 0;
1103		return 0;
1104	}
1105	dbg_io_ops->write_char('+');
1106	put_packet(remcom_out_buffer);
1107	return 0;
1108}
1109
1110/**
1111 * gdbstub_exit - Send an exit message to GDB
1112 * @status: The exit code to report.
1113 */
1114void gdbstub_exit(int status)
1115{
1116	unsigned char checksum, ch, buffer[3];
1117	int loop;
1118
1119	if (!kgdb_connected)
1120		return;
1121	kgdb_connected = 0;
1122
1123	if (!dbg_io_ops || dbg_kdb_mode)
1124		return;
1125
1126	buffer[0] = 'W';
1127	buffer[1] = hex_asc_hi(status);
1128	buffer[2] = hex_asc_lo(status);
1129
1130	dbg_io_ops->write_char('$');
1131	checksum = 0;
1132
1133	for (loop = 0; loop < 3; loop++) {
1134		ch = buffer[loop];
1135		checksum += ch;
1136		dbg_io_ops->write_char(ch);
1137	}
1138
1139	dbg_io_ops->write_char('#');
1140	dbg_io_ops->write_char(hex_asc_hi(checksum));
1141	dbg_io_ops->write_char(hex_asc_lo(checksum));
1142
1143	/* make sure the output is flushed, lest the bootloader clobber it */
1144	if (dbg_io_ops->flush)
1145		dbg_io_ops->flush();
1146}