gdbstub.c 25.5 KB
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/*
 * 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>
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 * Copyright (C) 2004 Pavel Machek <pavel@ucw.cz>
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 * 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>
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#include <linux/sched/signal.h>
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#include <linux/kgdb.h>
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#include <linux/kdb.h>
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#include <linux/serial_core.h>
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#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];
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static int			gdbstub_use_prev_in_buf;
static int			gdbstub_prev_in_buf_pos;
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/* Storage for the registers, in GDB format. */
static unsigned long		gdb_regs[(NUMREGBYTES +
					sizeof(unsigned long) - 1) /
					sizeof(unsigned long)];

/*
 * GDB remote protocol parser:
 */

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

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	if (unlikely(gdbstub_use_prev_in_buf)) {
		if (gdbstub_prev_in_buf_pos < gdbstub_use_prev_in_buf)
			return remcom_in_buffer[gdbstub_prev_in_buf_pos++];
		else
			gdbstub_use_prev_in_buf = 0;
	}

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	/* 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
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/* 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:
		 */
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		while ((ch = (gdbstub_read_wait())) != '$')
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			/* nothing */;

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

		count = 0;

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

		if (ch == '#') {
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			xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
			xmitcsum += hex_to_bin(gdbstub_read_wait());
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			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();
		}
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		buffer[count] = 0;
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	} 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. */
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		ch = gdbstub_read_wait();
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		if (ch == 3)
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			ch = gdbstub_read_wait();
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		/* 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;

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

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	/* '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++)
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			bufptr = hex_byte_pack(bufptr, s[i]);
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		*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.
 */
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char *kgdb_mem2hex(char *mem, char *buf, int count)
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{
	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);
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	if (err)
		return NULL;
	while (count > 0) {
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		buf = hex_byte_pack(buf, *tmp);
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		tmp++;
		count--;
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	}
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	*buf = 0;
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	return buf;
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}

/*
 * 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--;
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		*tmp_raw = hex_to_bin(*tmp_hex--);
		*tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
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	}

	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) {
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		hex_val = hex_to_bin(**ptr);
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		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);
}

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#if DBG_MAX_REG_NUM > 0
void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
	int i;
	int idx = 0;
	char *ptr = (char *)gdb_regs;

	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
		dbg_get_reg(i, ptr + idx, regs);
		idx += dbg_reg_def[i].size;
	}
}

void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
	int i;
	int idx = 0;
	char *ptr = (char *)gdb_regs;

	for (i = 0; i < DBG_MAX_REG_NUM; i++) {
		dbg_set_reg(i, ptr + idx, regs);
		idx += dbg_reg_def[i].size;
	}
}
#endif /* DBG_MAX_REG_NUM > 0 */

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/* 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.
 */

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#define BUF_THREAD_ID_SIZE	8
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static char *pack_threadid(char *pkt, unsigned char *id)
{
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	unsigned char *limit;
	int lzero = 1;

	limit = id + (BUF_THREAD_ID_SIZE / 2);
	while (id < limit) {
		if (!lzero || *id != 0) {
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			pkt = hex_byte_pack(pkt, *id);
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			lzero = 0;
		}
		id++;
	}
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	if (lzero)
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		pkt = hex_byte_pack(pkt, 0);
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	return pkt;
}

static void int_to_threadref(unsigned char *id, int value)
{
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	put_unaligned_be32(value, id);
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}

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';
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	hex_byte_pack(&remcom_out_buffer[1], ks->signo);
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}

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static void gdb_get_regs_helper(struct kgdb_state *ks)
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{
	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);
	}
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}

/* Handle the 'g' get registers request */
static void gdb_cmd_getregs(struct kgdb_state *ks)
{
	gdb_get_regs_helper(ks);
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	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;
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	char *err;
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	if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
					kgdb_hex2long(&ptr, &length) > 0) {
		err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
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		if (!err)
			error_packet(remcom_out_buffer, -EINVAL);
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	} 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");
}

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#if DBG_MAX_REG_NUM > 0
static char *gdb_hex_reg_helper(int regnum, char *out)
{
	int i;
	int offset = 0;

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

/* Handle the 'p' individual regster get */
static void gdb_cmd_reg_get(struct kgdb_state *ks)
{
	unsigned long regnum;
	char *ptr = &remcom_in_buffer[1];

	kgdb_hex2long(&ptr, &regnum);
	if (regnum >= DBG_MAX_REG_NUM) {
		error_packet(remcom_out_buffer, -EINVAL);
		return;
	}
	gdb_get_regs_helper(ks);
	gdb_hex_reg_helper(regnum, remcom_out_buffer);
}

/* Handle the 'P' individual regster set */
static void gdb_cmd_reg_set(struct kgdb_state *ks)
{
	unsigned long regnum;
	char *ptr = &remcom_in_buffer[1];
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	int i = 0;
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	kgdb_hex2long(&ptr, &regnum);
	if (*ptr++ != '=' ||
	    !(!kgdb_usethread || kgdb_usethread == current) ||
	    !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
		error_packet(remcom_out_buffer, -EINVAL);
		return;
	}
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	memset(gdb_regs, 0, sizeof(gdb_regs));
	while (i < sizeof(gdb_regs) * 2)
		if (hex_to_bin(ptr[i]) >= 0)
			i++;
		else
			break;
	i = i / 2;
	kgdb_hex2mem(ptr, (char *)gdb_regs, i);
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	dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
	strcpy(remcom_out_buffer, "OK");
}
#endif /* DBG_MAX_REG_NUM > 0 */

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/* 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;
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	unsigned char thref[BUF_THREAD_ID_SIZE];
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	char *ptr;
	int i;
	int cpu;
	int finished = 0;

	switch (remcom_in_buffer[1]) {
	case 's':
	case 'f':
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		if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
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			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);
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				ptr = pack_threadid(ptr, thref);
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				*(ptr++) = ',';
				i++;
			}
		}

		do_each_thread(g, p) {
			if (i >= ks->thr_query && !finished) {
				int_to_threadref(thref, p->pid);
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				ptr = pack_threadid(ptr, thref);
732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750
				*(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':
751
		if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
752
			break;
753

754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772
		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;
773 774 775 776 777 778 779 780 781 782 783 784 785 786
#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;

787
			kdb_common_init_state(ks);
788
			kdb_parse(remcom_out_buffer);
789 790
			kdb_common_deinit_state();

791 792 793 794
			strcpy(remcom_out_buffer, "OK");
		}
		break;
#endif
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
	}
}

/* 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;

949
	/* Initialize comm buffer and globals. */
950
	memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
951 952 953
	kgdb_usethread = kgdb_info[ks->cpu].task;
	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
	ks->pass_exception = 0;
954 955

	if (kgdb_connected) {
956
		unsigned char thref[BUF_THREAD_ID_SIZE];
957 958 959 960 961
		char *ptr;

		/* Reply to host that an exception has occurred */
		ptr = remcom_out_buffer;
		*ptr++ = 'T';
962
		ptr = hex_byte_pack(ptr, ks->signo);
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
		ptr += strlen(strcpy(ptr, "thread:"));
		int_to_threadref(thref, shadow_pid(current->pid));
		ptr = pack_threadid(ptr, thref);
		*ptr++ = ';';
		put_packet(remcom_out_buffer);
	}

	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;
994 995 996 997 998 999 1000 1001
#if DBG_MAX_REG_NUM > 0
		case 'p': /* pXX Return gdb register XX (in hex) */
			gdb_cmd_reg_get(ks);
			break;
		case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
			gdb_cmd_reg_set(ks);
			break;
#endif /* DBG_MAX_REG_NUM > 0 */
1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028
		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;
1029 1030 1031 1032 1033 1034 1035
#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
1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080
		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;
}
1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098

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;
1099 1100 1101 1102 1103
	case '$':
		strcpy(remcom_in_buffer, cmd);
		gdbstub_use_prev_in_buf = strlen(remcom_in_buffer);
		gdbstub_prev_in_buf_pos = 0;
		return 0;
1104 1105 1106 1107 1108
	}
	dbg_io_ops->write_char('+');
	put_packet(remcom_out_buffer);
	return 0;
}
1109 1110 1111 1112 1113 1114 1115 1116 1117 1118

/**
 * gdbstub_exit - Send an exit message to GDB
 * @status: The exit code to report.
 */
void gdbstub_exit(int status)
{
	unsigned char checksum, ch, buffer[3];
	int loop;

1119 1120 1121 1122 1123 1124 1125
	if (!kgdb_connected)
		return;
	kgdb_connected = 0;

	if (!dbg_io_ops || dbg_kdb_mode)
		return;

1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143
	buffer[0] = 'W';
	buffer[1] = hex_asc_hi(status);
	buffer[2] = hex_asc_lo(status);

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

	for (loop = 0; loop < 3; loop++) {
		ch = buffer[loop];
		checksum += ch;
		dbg_io_ops->write_char(ch);
	}

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

	/* make sure the output is flushed, lest the bootloader clobber it */
1144 1145
	if (dbg_io_ops->flush)
		dbg_io_ops->flush();
1146
}