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32 results

arm_sdei.c

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  • gdbstub.c 24.34 KiB
    /*
     * Kernel Debug Core
     *
     * Maintainer: Jason Wessel <jason.wessel@windriver.com>
     *
     * Copyright (C) 2000-2001 VERITAS Software Corporation.
     * Copyright (C) 2002-2004 Timesys Corporation
     * Copyright (C) 2003-2004 Amit S. Kale <amitkale@linsyssoft.com>
     * Copyright (C) 2004 Pavel Machek <pavel@suse.cz>
     * Copyright (C) 2004-2006 Tom Rini <trini@kernel.crashing.org>
     * Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd.
     * Copyright (C) 2005-2009 Wind River Systems, Inc.
     * Copyright (C) 2007 MontaVista Software, Inc.
     * Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
     *
     * Contributors at various stages not listed above:
     *  Jason Wessel ( jason.wessel@windriver.com )
     *  George Anzinger <george@mvista.com>
     *  Anurekh Saxena (anurekh.saxena@timesys.com)
     *  Lake Stevens Instrument Division (Glenn Engel)
     *  Jim Kingdon, Cygnus Support.
     *
     * Original KGDB stub: David Grothe <dave@gcom.com>,
     * Tigran Aivazian <tigran@sco.com>
     *
     * This file is licensed under the terms of the GNU General Public License
     * version 2. This program is licensed "as is" without any warranty of any
     * kind, whether express or implied.
     */
    
    #include <linux/kernel.h>
    #include <linux/kgdb.h>
    #include <linux/kdb.h>
    #include <linux/reboot.h>
    #include <linux/uaccess.h>
    #include <asm/cacheflush.h>
    #include <asm/unaligned.h>
    #include "debug_core.h"
    
    #define KGDB_MAX_THREAD_QUERY 17
    
    /* Our I/O buffers. */
    static char			remcom_in_buffer[BUFMAX];
    static char			remcom_out_buffer[BUFMAX];
    
    /* Storage for the registers, in GDB format. */
    static unsigned long		gdb_regs[(NUMREGBYTES +
    					sizeof(unsigned long) - 1) /
    					sizeof(unsigned long)];
    
    /*
     * GDB remote protocol parser:
     */
    
    #ifdef CONFIG_KGDB_KDB
    static int gdbstub_read_wait(void)
    {
    	int ret = -1;
    	int i;
    
    	/* poll any additional I/O interfaces that are defined */
    	while (ret < 0)
    		for (i = 0; kdb_poll_funcs[i] != NULL; i++) {
    			ret = kdb_poll_funcs[i]();
    			if (ret > 0)
    				break;
    		}
    	return ret;
    }
    #else
    static int gdbstub_read_wait(void)
    {
    	int ret = dbg_io_ops->read_char();
    	while (ret == NO_POLL_CHAR)
    		ret = dbg_io_ops->read_char();
    	return ret;
    }
    #endif
    /* scan for the sequence $<data>#<checksum> */
    static void get_packet(char *buffer)
    {
    	unsigned char checksum;
    	unsigned char xmitcsum;
    	int count;
    	char ch;
    
    	do {
    		/*
    		 * Spin and wait around for the start character, ignore all
    		 * other characters:
    		 */
    		while ((ch = (gdbstub_read_wait())) != '$')
    			/* nothing */;
    
    		kgdb_connected = 1;
    		checksum = 0;
    		xmitcsum = -1;
    
    		count = 0;
    
    		/*
    		 * now, read until a # or end of buffer is found:
    		 */
    		while (count < (BUFMAX - 1)) {
    			ch = gdbstub_read_wait();
    			if (ch == '#')
    				break;
    			checksum = checksum + ch;
    			buffer[count] = ch;
    			count = count + 1;
    		}
    		buffer[count] = 0;
    
    		if (ch == '#') {
    			xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
    			xmitcsum += hex_to_bin(gdbstub_read_wait());
    
    			if (checksum != xmitcsum)
    				/* failed checksum */
    				dbg_io_ops->write_char('-');
    			else
    				/* successful transfer */
    				dbg_io_ops->write_char('+');
    			if (dbg_io_ops->flush)
    				dbg_io_ops->flush();
    		}
    	} while (checksum != xmitcsum);
    }
    
    /*
     * Send the packet in buffer.
     * Check for gdb connection if asked for.
     */
    static void put_packet(char *buffer)
    {
    	unsigned char checksum;
    	int count;
    	char ch;
    
    	/*
    	 * $<packet info>#<checksum>.
    	 */
    	while (1) {
    		dbg_io_ops->write_char('$');
    		checksum = 0;
    		count = 0;
    
    		while ((ch = buffer[count])) {
    			dbg_io_ops->write_char(ch);
    			checksum += ch;
    			count++;
    		}
    
    		dbg_io_ops->write_char('#');
    		dbg_io_ops->write_char(hex_asc_hi(checksum));
    		dbg_io_ops->write_char(hex_asc_lo(checksum));
    		if (dbg_io_ops->flush)
    			dbg_io_ops->flush();
    
    		/* Now see what we get in reply. */
    		ch = gdbstub_read_wait();
    
    		if (ch == 3)
    			ch = gdbstub_read_wait();
    
    		/* If we get an ACK, we are done. */
    		if (ch == '+')
    			return;
    
    		/*
    		 * If we get the start of another packet, this means
    		 * that GDB is attempting to reconnect.  We will NAK
    		 * the packet being sent, and stop trying to send this
    		 * packet.
    		 */
    		if (ch == '$') {
    			dbg_io_ops->write_char('-');
    			if (dbg_io_ops->flush)
    				dbg_io_ops->flush();
    			return;
    		}
    	}
    }
    
    static char gdbmsgbuf[BUFMAX + 1];
    
    void gdbstub_msg_write(const char *s, int len)
    {
    	char *bufptr;
    	int wcount;
    	int i;
    
    	if (len == 0)
    		len = strlen(s);
    
    	/* 'O'utput */
    	gdbmsgbuf[0] = 'O';
    
    	/* Fill and send buffers... */
    	while (len > 0) {
    		bufptr = gdbmsgbuf + 1;
    
    		/* Calculate how many this time */
    		if ((len << 1) > (BUFMAX - 2))
    			wcount = (BUFMAX - 2) >> 1;
    		else
    			wcount = len;
    
    		/* Pack in hex chars */
    		for (i = 0; i < wcount; i++)
    			bufptr = pack_hex_byte(bufptr, s[i]);
    		*bufptr = '\0';
    
    		/* Move up */
    		s += wcount;
    		len -= wcount;
    
    		/* Write packet */
    		put_packet(gdbmsgbuf);
    	}
    }
    
    /*
     * Convert the memory pointed to by mem into hex, placing result in
     * buf.  Return a pointer to the last char put in buf (null). May
     * return an error.
     */
    char *kgdb_mem2hex(char *mem, char *buf, int count)
    {
    	char *tmp;
    	int err;
    
    	/*
    	 * We use the upper half of buf as an intermediate buffer for the
    	 * raw memory copy.  Hex conversion will work against this one.
    	 */
    	tmp = buf + count;
    
    	err = probe_kernel_read(tmp, mem, count);
    	if (err)
    		return NULL;
    	while (count > 0) {
    		buf = pack_hex_byte(buf, *tmp);
    		tmp++;
    		count--;
    	}
    	*buf = 0;
    
    	return buf;
    }
    
    /*
     * Convert the hex array pointed to by buf into binary to be placed in
     * mem.  Return a pointer to the character AFTER the last byte
     * written.  May return an error.
     */
    int kgdb_hex2mem(char *buf, char *mem, int count)
    {
    	char *tmp_raw;
    	char *tmp_hex;
    
    	/*
    	 * We use the upper half of buf as an intermediate buffer for the
    	 * raw memory that is converted from hex.
    	 */
    	tmp_raw = buf + count * 2;
    
    	tmp_hex = tmp_raw - 1;
    	while (tmp_hex >= buf) {
    		tmp_raw--;
    		*tmp_raw = hex_to_bin(*tmp_hex--);
    		*tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
    	}
    
    	return probe_kernel_write(mem, tmp_raw, count);
    }
    
    /*
     * While we find nice hex chars, build a long_val.
     * Return number of chars processed.
     */
    int kgdb_hex2long(char **ptr, unsigned long *long_val)
    {
    	int hex_val;
    	int num = 0;
    	int negate = 0;
    
    	*long_val = 0;
    
    	if (**ptr == '-') {
    		negate = 1;
    		(*ptr)++;
    	}
    	while (**ptr) {
    		hex_val = hex_to_bin(**ptr);
    		if (hex_val < 0)
    			break;
    
    		*long_val = (*long_val << 4) | hex_val;
    		num++;
    		(*ptr)++;
    	}
    
    	if (negate)
    		*long_val = -*long_val;
    
    	return num;
    }
    
    /*
     * Copy the binary array pointed to by buf into mem.  Fix $, #, and
     * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success.
     * The input buf is overwitten with the result to write to mem.
     */
    static int kgdb_ebin2mem(char *buf, char *mem, int count)
    {
    	int size = 0;
    	char *c = buf;
    
    	while (count-- > 0) {
    		c[size] = *buf++;
    		if (c[size] == 0x7d)
    			c[size] = *buf++ ^ 0x20;
    		size++;
    	}
    
    	return probe_kernel_write(mem, c, size);
    }
    
    #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 */
    
    /* Write memory due to an 'M' or 'X' packet. */
    static int write_mem_msg(int binary)
    {
    	char *ptr = &remcom_in_buffer[1];
    	unsigned long addr;
    	unsigned long length;
    	int err;
    
    	if (kgdb_hex2long(&ptr, &addr) > 0 && *(ptr++) == ',' &&
    	    kgdb_hex2long(&ptr, &length) > 0 && *(ptr++) == ':') {
    		if (binary)
    			err = kgdb_ebin2mem(ptr, (char *)addr, length);
    		else
    			err = kgdb_hex2mem(ptr, (char *)addr, length);
    		if (err)
    			return err;
    		if (CACHE_FLUSH_IS_SAFE)
    			flush_icache_range(addr, addr + length);
    		return 0;
    	}
    
    	return -EINVAL;
    }
    
    static void error_packet(char *pkt, int error)
    {
    	error = -error;
    	pkt[0] = 'E';
    	pkt[1] = hex_asc[(error / 10)];
    	pkt[2] = hex_asc[(error % 10)];
    	pkt[3] = '\0';
    }
    
    /*
     * Thread ID accessors. We represent a flat TID space to GDB, where
     * the per CPU idle threads (which under Linux all have PID 0) are
     * remapped to negative TIDs.
     */
    
    #define BUF_THREAD_ID_SIZE	8
    
    static char *pack_threadid(char *pkt, unsigned char *id)
    {
    	unsigned char *limit;
    	int lzero = 1;
    
    	limit = id + (BUF_THREAD_ID_SIZE / 2);
    	while (id < limit) {
    		if (!lzero || *id != 0) {
    			pkt = pack_hex_byte(pkt, *id);
    			lzero = 0;
    		}
    		id++;
    	}
    
    	if (lzero)
    		pkt = pack_hex_byte(pkt, 0);
    
    	return pkt;
    }
    
    static void int_to_threadref(unsigned char *id, int value)
    {
    	put_unaligned_be32(value, id);
    }
    
    static struct task_struct *getthread(struct pt_regs *regs, int tid)
    {
    	/*
    	 * Non-positive TIDs are remapped to the cpu shadow information
    	 */
    	if (tid == 0 || tid == -1)
    		tid = -atomic_read(&kgdb_active) - 2;
    	if (tid < -1 && tid > -NR_CPUS - 2) {
    		if (kgdb_info[-tid - 2].task)
    			return kgdb_info[-tid - 2].task;
    		else
    			return idle_task(-tid - 2);
    	}
    	if (tid <= 0) {
    		printk(KERN_ERR "KGDB: Internal thread select error\n");
    		dump_stack();
    		return NULL;
    	}
    
    	/*
    	 * find_task_by_pid_ns() does not take the tasklist lock anymore
    	 * but is nicely RCU locked - hence is a pretty resilient
    	 * thing to use:
    	 */
    	return find_task_by_pid_ns(tid, &init_pid_ns);
    }
    
    
    /*
     * Remap normal tasks to their real PID,
     * CPU shadow threads are mapped to -CPU - 2
     */
    static inline int shadow_pid(int realpid)
    {
    	if (realpid)
    		return realpid;
    
    	return -raw_smp_processor_id() - 2;
    }
    
    /*
     * All the functions that start with gdb_cmd are the various
     * operations to implement the handlers for the gdbserial protocol
     * where KGDB is communicating with an external debugger
     */
    
    /* Handle the '?' status packets */
    static void gdb_cmd_status(struct kgdb_state *ks)
    {
    	/*
    	 * We know that this packet is only sent
    	 * during initial connect.  So to be safe,
    	 * we clear out our breakpoints now in case
    	 * GDB is reconnecting.
    	 */
    	dbg_remove_all_break();
    
    	remcom_out_buffer[0] = 'S';
    	pack_hex_byte(&remcom_out_buffer[1], ks->signo);
    }
    
    static void gdb_get_regs_helper(struct kgdb_state *ks)
    {
    	struct task_struct *thread;
    	void *local_debuggerinfo;
    	int i;
    
    	thread = kgdb_usethread;
    	if (!thread) {
    		thread = kgdb_info[ks->cpu].task;
    		local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
    	} else {
    		local_debuggerinfo = NULL;
    		for_each_online_cpu(i) {
    			/*
    			 * Try to find the task on some other
    			 * or possibly this node if we do not
    			 * find the matching task then we try
    			 * to approximate the results.
    			 */
    			if (thread == kgdb_info[i].task)
    				local_debuggerinfo = kgdb_info[i].debuggerinfo;
    		}
    	}
    
    	/*
    	 * All threads that don't have debuggerinfo should be
    	 * in schedule() sleeping, since all other CPUs
    	 * are in kgdb_wait, and thus have debuggerinfo.
    	 */
    	if (local_debuggerinfo) {
    		pt_regs_to_gdb_regs(gdb_regs, local_debuggerinfo);
    	} else {
    		/*
    		 * Pull stuff saved during switch_to; nothing
    		 * else is accessible (or even particularly
    		 * relevant).
    		 *
    		 * This should be enough for a stack trace.
    		 */
    		sleeping_thread_to_gdb_regs(gdb_regs, thread);
    	}
    }
    
    /* Handle the 'g' get registers request */
    static void gdb_cmd_getregs(struct kgdb_state *ks)
    {
    	gdb_get_regs_helper(ks);
    	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;
    	char *err;
    
    	if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
    					kgdb_hex2long(&ptr, &length) > 0) {
    		err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
    		if (!err)
    			error_packet(remcom_out_buffer, -EINVAL);
    	} 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");
    }
    
    #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];
    	int i = 0;
    
    	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;
    	}
    	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);
    	dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
    	strcpy(remcom_out_buffer, "OK");
    }
    #endif /* DBG_MAX_REG_NUM > 0 */
    
    /* Handle the 'X' memory binary write bytes */
    static void gdb_cmd_binwrite(struct kgdb_state *ks)
    {
    	int err = write_mem_msg(1);
    
    	if (err)
    		error_packet(remcom_out_buffer, err);
    	else
    		strcpy(remcom_out_buffer, "OK");
    }
    
    /* Handle the 'D' or 'k', detach or kill packets */
    static void gdb_cmd_detachkill(struct kgdb_state *ks)
    {
    	int error;
    
    	/* The detach case */
    	if (remcom_in_buffer[0] == 'D') {
    		error = dbg_remove_all_break();
    		if (error < 0) {
    			error_packet(remcom_out_buffer, error);
    		} else {
    			strcpy(remcom_out_buffer, "OK");
    			kgdb_connected = 0;
    		}
    		put_packet(remcom_out_buffer);
    	} else {
    		/*
    		 * Assume the kill case, with no exit code checking,
    		 * trying to force detach the debugger:
    		 */
    		dbg_remove_all_break();
    		kgdb_connected = 0;
    	}
    }
    
    /* Handle the 'R' reboot packets */
    static int gdb_cmd_reboot(struct kgdb_state *ks)
    {
    	/* For now, only honor R0 */
    	if (strcmp(remcom_in_buffer, "R0") == 0) {
    		printk(KERN_CRIT "Executing emergency reboot\n");
    		strcpy(remcom_out_buffer, "OK");
    		put_packet(remcom_out_buffer);
    
    		/*
    		 * Execution should not return from
    		 * machine_emergency_restart()
    		 */
    		machine_emergency_restart();
    		kgdb_connected = 0;
    
    		return 1;
    	}
    	return 0;
    }
    
    /* Handle the 'q' query packets */
    static void gdb_cmd_query(struct kgdb_state *ks)
    {
    	struct task_struct *g;
    	struct task_struct *p;
    	unsigned char thref[BUF_THREAD_ID_SIZE];
    	char *ptr;
    	int i;
    	int cpu;
    	int finished = 0;
    
    	switch (remcom_in_buffer[1]) {
    	case 's':
    	case 'f':
    		if (memcmp(remcom_in_buffer + 2, "ThreadInfo", 10))
    			break;
    
    		i = 0;
    		remcom_out_buffer[0] = 'm';
    		ptr = remcom_out_buffer + 1;
    		if (remcom_in_buffer[1] == 'f') {
    			/* Each cpu is a shadow thread */
    			for_each_online_cpu(cpu) {
    				ks->thr_query = 0;
    				int_to_threadref(thref, -cpu - 2);
    				ptr = pack_threadid(ptr, thref);
    				*(ptr++) = ',';
    				i++;
    			}
    		}
    
    		do_each_thread(g, p) {
    			if (i >= ks->thr_query && !finished) {
    				int_to_threadref(thref, p->pid);
    				ptr = pack_threadid(ptr, thref);
    				*(ptr++) = ',';
    				ks->thr_query++;
    				if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
    					finished = 1;
    			}
    			i++;
    		} while_each_thread(g, p);
    
    		*(--ptr) = '\0';
    		break;
    
    	case 'C':
    		/* Current thread id */
    		strcpy(remcom_out_buffer, "QC");
    		ks->threadid = shadow_pid(current->pid);
    		int_to_threadref(thref, ks->threadid);
    		pack_threadid(remcom_out_buffer + 2, thref);
    		break;
    	case 'T':
    		if (memcmp(remcom_in_buffer + 1, "ThreadExtraInfo,", 16))
    			break;
    
    		ks->threadid = 0;
    		ptr = remcom_in_buffer + 17;
    		kgdb_hex2long(&ptr, &ks->threadid);
    		if (!getthread(ks->linux_regs, ks->threadid)) {
    			error_packet(remcom_out_buffer, -EINVAL);
    			break;
    		}
    		if ((int)ks->threadid > 0) {
    			kgdb_mem2hex(getthread(ks->linux_regs,
    					ks->threadid)->comm,
    					remcom_out_buffer, 16);
    		} else {
    			static char tmpstr[23 + BUF_THREAD_ID_SIZE];
    
    			sprintf(tmpstr, "shadowCPU%d",
    					(int)(-ks->threadid - 2));
    			kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
    		}
    		break;
    #ifdef CONFIG_KGDB_KDB
    	case 'R':
    		if (strncmp(remcom_in_buffer, "qRcmd,", 6) == 0) {
    			int len = strlen(remcom_in_buffer + 6);
    
    			if ((len % 2) != 0) {
    				strcpy(remcom_out_buffer, "E01");
    				break;
    			}
    			kgdb_hex2mem(remcom_in_buffer + 6,
    				     remcom_out_buffer, len);
    			len = len / 2;
    			remcom_out_buffer[len++] = 0;
    
    			kdb_parse(remcom_out_buffer);
    			strcpy(remcom_out_buffer, "OK");
    		}
    		break;
    #endif
    	}
    }
    
    /* Handle the 'H' task query packets */
    static void gdb_cmd_task(struct kgdb_state *ks)
    {
    	struct task_struct *thread;
    	char *ptr;
    
    	switch (remcom_in_buffer[1]) {
    	case 'g':
    		ptr = &remcom_in_buffer[2];
    		kgdb_hex2long(&ptr, &ks->threadid);
    		thread = getthread(ks->linux_regs, ks->threadid);
    		if (!thread && ks->threadid > 0) {
    			error_packet(remcom_out_buffer, -EINVAL);
    			break;
    		}
    		kgdb_usethread = thread;
    		ks->kgdb_usethreadid = ks->threadid;
    		strcpy(remcom_out_buffer, "OK");
    		break;
    	case 'c':
    		ptr = &remcom_in_buffer[2];
    		kgdb_hex2long(&ptr, &ks->threadid);
    		if (!ks->threadid) {
    			kgdb_contthread = NULL;
    		} else {
    			thread = getthread(ks->linux_regs, ks->threadid);
    			if (!thread && ks->threadid > 0) {
    				error_packet(remcom_out_buffer, -EINVAL);
    				break;
    			}
    			kgdb_contthread = thread;
    		}
    		strcpy(remcom_out_buffer, "OK");
    		break;
    	}
    }
    
    /* Handle the 'T' thread query packets */
    static void gdb_cmd_thread(struct kgdb_state *ks)
    {
    	char *ptr = &remcom_in_buffer[1];
    	struct task_struct *thread;
    
    	kgdb_hex2long(&ptr, &ks->threadid);
    	thread = getthread(ks->linux_regs, ks->threadid);
    	if (thread)
    		strcpy(remcom_out_buffer, "OK");
    	else
    		error_packet(remcom_out_buffer, -EINVAL);
    }
    
    /* Handle the 'z' or 'Z' breakpoint remove or set packets */
    static void gdb_cmd_break(struct kgdb_state *ks)
    {
    	/*
    	 * Since GDB-5.3, it's been drafted that '0' is a software
    	 * breakpoint, '1' is a hardware breakpoint, so let's do that.
    	 */
    	char *bpt_type = &remcom_in_buffer[1];
    	char *ptr = &remcom_in_buffer[2];
    	unsigned long addr;
    	unsigned long length;
    	int error = 0;
    
    	if (arch_kgdb_ops.set_hw_breakpoint && *bpt_type >= '1') {
    		/* Unsupported */
    		if (*bpt_type > '4')
    			return;
    	} else {
    		if (*bpt_type != '0' && *bpt_type != '1')
    			/* Unsupported. */
    			return;
    	}
    
    	/*
    	 * Test if this is a hardware breakpoint, and
    	 * if we support it:
    	 */
    	if (*bpt_type == '1' && !(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT))
    		/* Unsupported. */
    		return;
    
    	if (*(ptr++) != ',') {
    		error_packet(remcom_out_buffer, -EINVAL);
    		return;
    	}
    	if (!kgdb_hex2long(&ptr, &addr)) {
    		error_packet(remcom_out_buffer, -EINVAL);
    		return;
    	}
    	if (*(ptr++) != ',' ||
    		!kgdb_hex2long(&ptr, &length)) {
    		error_packet(remcom_out_buffer, -EINVAL);
    		return;
    	}
    
    	if (remcom_in_buffer[0] == 'Z' && *bpt_type == '0')
    		error = dbg_set_sw_break(addr);
    	else if (remcom_in_buffer[0] == 'z' && *bpt_type == '0')
    		error = dbg_remove_sw_break(addr);
    	else if (remcom_in_buffer[0] == 'Z')
    		error = arch_kgdb_ops.set_hw_breakpoint(addr,
    			(int)length, *bpt_type - '0');
    	else if (remcom_in_buffer[0] == 'z')
    		error = arch_kgdb_ops.remove_hw_breakpoint(addr,
    			(int) length, *bpt_type - '0');
    
    	if (error == 0)
    		strcpy(remcom_out_buffer, "OK");
    	else
    		error_packet(remcom_out_buffer, error);
    }
    
    /* Handle the 'C' signal / exception passing packets */
    static int gdb_cmd_exception_pass(struct kgdb_state *ks)
    {
    	/* C09 == pass exception
    	 * C15 == detach kgdb, pass exception
    	 */
    	if (remcom_in_buffer[1] == '0' && remcom_in_buffer[2] == '9') {
    
    		ks->pass_exception = 1;
    		remcom_in_buffer[0] = 'c';
    
    	} else if (remcom_in_buffer[1] == '1' && remcom_in_buffer[2] == '5') {
    
    		ks->pass_exception = 1;
    		remcom_in_buffer[0] = 'D';
    		dbg_remove_all_break();
    		kgdb_connected = 0;
    		return 1;
    
    	} else {
    		gdbstub_msg_write("KGDB only knows signal 9 (pass)"
    			" and 15 (pass and disconnect)\n"
    			"Executing a continue without signal passing\n", 0);
    		remcom_in_buffer[0] = 'c';
    	}
    
    	/* Indicate fall through */
    	return -1;
    }
    
    /*
     * This function performs all gdbserial command procesing
     */
    int gdb_serial_stub(struct kgdb_state *ks)
    {
    	int error = 0;
    	int tmp;
    
    	/* Initialize comm buffer and globals. */
    	memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
    	kgdb_usethread = kgdb_info[ks->cpu].task;
    	ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
    	ks->pass_exception = 0;
    
    	if (kgdb_connected) {
    		unsigned char thref[BUF_THREAD_ID_SIZE];
    		char *ptr;
    
    		/* Reply to host that an exception has occurred */
    		ptr = remcom_out_buffer;
    		*ptr++ = 'T';
    		ptr = pack_hex_byte(ptr, ks->signo);
    		ptr += strlen(strcpy(ptr, "thread:"));
    		int_to_threadref(thref, shadow_pid(current->pid));
    		ptr = pack_threadid(ptr, thref);
    		*ptr++ = ';';
    		put_packet(remcom_out_buffer);
    	}
    
    	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;
    #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 */
    		case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
    			gdb_cmd_binwrite(ks);
    			break;
    			/* kill or detach. KGDB should treat this like a
    			 * continue.
    			 */
    		case 'D': /* Debugger detach */
    		case 'k': /* Debugger detach via kill */
    			gdb_cmd_detachkill(ks);
    			goto default_handle;
    		case 'R': /* Reboot */
    			if (gdb_cmd_reboot(ks))
    				goto default_handle;
    			break;
    		case 'q': /* query command */
    			gdb_cmd_query(ks);
    			break;
    		case 'H': /* task related */
    			gdb_cmd_task(ks);
    			break;
    		case 'T': /* Query thread status */
    			gdb_cmd_thread(ks);
    			break;
    		case 'z': /* Break point remove */
    		case 'Z': /* Break point set */
    			gdb_cmd_break(ks);
    			break;
    #ifdef CONFIG_KGDB_KDB
    		case '3': /* Escape into back into kdb */
    			if (remcom_in_buffer[1] == '\0') {
    				gdb_cmd_detachkill(ks);
    				return DBG_PASS_EVENT;
    			}
    #endif
    		case 'C': /* Exception passing */
    			tmp = gdb_cmd_exception_pass(ks);
    			if (tmp > 0)
    				goto default_handle;
    			if (tmp == 0)
    				break;
    			/* Fall through on tmp < 0 */
    		case 'c': /* Continue packet */
    		case 's': /* Single step packet */
    			if (kgdb_contthread && kgdb_contthread != current) {
    				/* Can't switch threads in kgdb */
    				error_packet(remcom_out_buffer, -EINVAL);
    				break;
    			}
    			dbg_activate_sw_breakpoints();
    			/* Fall through to default processing */
    		default:
    default_handle:
    			error = kgdb_arch_handle_exception(ks->ex_vector,
    						ks->signo,
    						ks->err_code,
    						remcom_in_buffer,
    						remcom_out_buffer,
    						ks->linux_regs);
    			/*
    			 * Leave cmd processing on error, detach,
    			 * kill, continue, or single step.
    			 */
    			if (error >= 0 || remcom_in_buffer[0] == 'D' ||
    			    remcom_in_buffer[0] == 'k') {
    				error = 0;
    				goto kgdb_exit;
    			}
    
    		}
    
    		/* reply to the request */
    		put_packet(remcom_out_buffer);
    	}
    
    kgdb_exit:
    	if (ks->pass_exception)
    		error = 1;
    	return error;
    }
    
    int gdbstub_state(struct kgdb_state *ks, char *cmd)
    {
    	int error;
    
    	switch (cmd[0]) {
    	case 'e':
    		error = kgdb_arch_handle_exception(ks->ex_vector,
    						   ks->signo,
    						   ks->err_code,
    						   remcom_in_buffer,
    						   remcom_out_buffer,
    						   ks->linux_regs);
    		return error;
    	case 's':
    	case 'c':
    		strcpy(remcom_in_buffer, cmd);
    		return 0;
    	case '?':
    		gdb_cmd_status(ks);
    		break;
    	case '\0':
    		strcpy(remcom_out_buffer, "");
    		break;
    	}
    	dbg_io_ops->write_char('+');
    	put_packet(remcom_out_buffer);
    	return 0;
    }