diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
new file mode 100644
index 0000000..0c4f00a
--- /dev/null
+++ b/kernel/trace/trace_kprobe.c
@@ -0,0 +1,1202 @@
+/*
+ * kprobe based kernel tracer
+ *
+ * Created by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/kprobes.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/debugfs.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/ptrace.h>
+
+#include "trace.h"
+#include "trace_output.h"
+
+#define TRACE_KPROBE_ARGS 6
+#define MAX_ARGSTR_LEN 63
+
+/* currently, trace_kprobe only supports X86. */
+
+struct fetch_func {
+	unsigned long (*func)(struct pt_regs *, void *);
+	void *data;
+};
+
+static __kprobes unsigned long call_fetch(struct fetch_func *f,
+					  struct pt_regs *regs)
+{
+	return f->func(regs, f->data);
+}
+
+/* fetch handlers */
+static __kprobes unsigned long fetch_register(struct pt_regs *regs,
+					      void *offset)
+{
+	return regs_get_register(regs, (unsigned int)((unsigned long)offset));
+}
+
+static __kprobes unsigned long fetch_stack(struct pt_regs *regs,
+					   void *num)
+{
+	return regs_get_kernel_stack_nth(regs,
+					 (unsigned int)((unsigned long)num));
+}
+
+static __kprobes unsigned long fetch_memory(struct pt_regs *regs, void *addr)
+{
+	unsigned long retval;
+
+	if (probe_kernel_address(addr, retval))
+		return 0;
+	return retval;
+}
+
+static __kprobes unsigned long fetch_argument(struct pt_regs *regs, void *num)
+{
+	return regs_get_argument_nth(regs, (unsigned int)((unsigned long)num));
+}
+
+static __kprobes unsigned long fetch_retvalue(struct pt_regs *regs,
+					      void *dummy)
+{
+	return regs_return_value(regs);
+}
+
+static __kprobes unsigned long fetch_ip(struct pt_regs *regs, void *dummy)
+{
+	return instruction_pointer(regs);
+}
+
+static __kprobes unsigned long fetch_stack_address(struct pt_regs *regs,
+						   void *dummy)
+{
+	return kernel_stack_pointer(regs);
+}
+
+/* Memory fetching by symbol */
+struct symbol_cache {
+	char *symbol;
+	long offset;
+	unsigned long addr;
+};
+
+static unsigned long update_symbol_cache(struct symbol_cache *sc)
+{
+	sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
+	if (sc->addr)
+		sc->addr += sc->offset;
+	return sc->addr;
+}
+
+static void free_symbol_cache(struct symbol_cache *sc)
+{
+	kfree(sc->symbol);
+	kfree(sc);
+}
+
+static struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
+{
+	struct symbol_cache *sc;
+
+	if (!sym || strlen(sym) == 0)
+		return NULL;
+	sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
+	if (!sc)
+		return NULL;
+
+	sc->symbol = kstrdup(sym, GFP_KERNEL);
+	if (!sc->symbol) {
+		kfree(sc);
+		return NULL;
+	}
+	sc->offset = offset;
+
+	update_symbol_cache(sc);
+	return sc;
+}
+
+static __kprobes unsigned long fetch_symbol(struct pt_regs *regs, void *data)
+{
+	struct symbol_cache *sc = data;
+
+	if (sc->addr)
+		return fetch_memory(regs, (void *)sc->addr);
+	else
+		return 0;
+}
+
+/* Special indirect memory access interface */
+struct indirect_fetch_data {
+	struct fetch_func orig;
+	long offset;
+};
+
+static __kprobes unsigned long fetch_indirect(struct pt_regs *regs, void *data)
+{
+	struct indirect_fetch_data *ind = data;
+	unsigned long addr;
+
+	addr = call_fetch(&ind->orig, regs);
+	if (addr) {
+		addr += ind->offset;
+		return fetch_memory(regs, (void *)addr);
+	} else
+		return 0;
+}
+
+static __kprobes void free_indirect_fetch_data(struct indirect_fetch_data *data)
+{
+	if (data->orig.func == fetch_indirect)
+		free_indirect_fetch_data(data->orig.data);
+	else if (data->orig.func == fetch_symbol)
+		free_symbol_cache(data->orig.data);
+	kfree(data);
+}
+
+/**
+ * kprobe_trace_core
+ */
+
+struct trace_probe {
+	struct list_head	list;
+	union {
+		struct kprobe		kp;
+		struct kretprobe	rp;
+	};
+	const char		*symbol;	/* symbol name */
+	unsigned int		nr_args;
+	struct fetch_func	args[TRACE_KPROBE_ARGS];
+	struct ftrace_event_call	call;
+};
+
+static int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs);
+static int kretprobe_trace_func(struct kretprobe_instance *ri,
+				struct pt_regs *regs);
+
+static __kprobes int probe_is_return(struct trace_probe *tp)
+{
+	return (tp->rp.handler == kretprobe_trace_func);
+}
+
+static __kprobes const char *probe_symbol(struct trace_probe *tp)
+{
+	return tp->symbol ? tp->symbol : "unknown";
+}
+
+static __kprobes long probe_offset(struct trace_probe *tp)
+{
+	return (probe_is_return(tp)) ? tp->rp.kp.offset : tp->kp.offset;
+}
+
+static __kprobes void *probe_address(struct trace_probe *tp)
+{
+	return (probe_is_return(tp)) ? tp->rp.kp.addr : tp->kp.addr;
+}
+
+static int trace_arg_string(char *buf, size_t n, struct fetch_func *ff)
+{
+	int ret = -EINVAL;
+
+	if (ff->func == fetch_argument)
+		ret = snprintf(buf, n, "a%lu", (unsigned long)ff->data);
+	else if (ff->func == fetch_register) {
+		const char *name;
+		name = regs_query_register_name((unsigned int)((long)ff->data));
+		ret = snprintf(buf, n, "%%%s", name);
+	} else if (ff->func == fetch_stack)
+		ret = snprintf(buf, n, "s%lu", (unsigned long)ff->data);
+	else if (ff->func == fetch_memory)
+		ret = snprintf(buf, n, "@0x%p", ff->data);
+	else if (ff->func == fetch_symbol) {
+		struct symbol_cache *sc = ff->data;
+		ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
+	} else if (ff->func == fetch_retvalue)
+		ret = snprintf(buf, n, "rv");
+	else if (ff->func == fetch_ip)
+		ret = snprintf(buf, n, "ra");
+	else if (ff->func == fetch_stack_address)
+		ret = snprintf(buf, n, "sa");
+	else if (ff->func == fetch_indirect) {
+		struct indirect_fetch_data *id = ff->data;
+		size_t l = 0;
+		ret = snprintf(buf, n, "%+ld(", id->offset);
+		if (ret >= n)
+			goto end;
+		l += ret;
+		ret = trace_arg_string(buf + l, n - l, &id->orig);
+		if (ret < 0)
+			goto end;
+		l += ret;
+		ret = snprintf(buf + l, n - l, ")");
+		ret += l;
+	}
+end:
+	if (ret >= n)
+		return -ENOSPC;
+	return ret;
+}
+
+static int register_probe_event(struct trace_probe *tp);
+static void unregister_probe_event(struct trace_probe *tp);
+
+static DEFINE_MUTEX(probe_lock);
+static LIST_HEAD(probe_list);
+
+static struct trace_probe *alloc_trace_probe(const char *symbol,
+					     const char *event)
+{
+	struct trace_probe *tp;
+
+	tp = kzalloc(sizeof(struct trace_probe), GFP_KERNEL);
+	if (!tp)
+		return ERR_PTR(-ENOMEM);
+
+	if (symbol) {
+		tp->symbol = kstrdup(symbol, GFP_KERNEL);
+		if (!tp->symbol)
+			goto error;
+	}
+	if (event) {
+		tp->call.name = kstrdup(event, GFP_KERNEL);
+		if (!tp->call.name)
+			goto error;
+	}
+
+	INIT_LIST_HEAD(&tp->list);
+	return tp;
+error:
+	kfree(tp->symbol);
+	kfree(tp);
+	return ERR_PTR(-ENOMEM);
+}
+
+static void free_trace_probe(struct trace_probe *tp)
+{
+	int i;
+
+	for (i = 0; i < tp->nr_args; i++)
+		if (tp->args[i].func == fetch_symbol)
+			free_symbol_cache(tp->args[i].data);
+		else if (tp->args[i].func == fetch_indirect)
+			free_indirect_fetch_data(tp->args[i].data);
+
+	kfree(tp->call.name);
+	kfree(tp->symbol);
+	kfree(tp);
+}
+
+static struct trace_probe *find_probe_event(const char *event)
+{
+	struct trace_probe *tp;
+
+	list_for_each_entry(tp, &probe_list, list)
+		if (tp->call.name && !strcmp(tp->call.name, event))
+			return tp;
+	return NULL;
+}
+
+static void __unregister_trace_probe(struct trace_probe *tp)
+{
+	if (probe_is_return(tp))
+		unregister_kretprobe(&tp->rp);
+	else
+		unregister_kprobe(&tp->kp);
+}
+
+/* Unregister a trace_probe and probe_event: call with locking probe_lock */
+static void unregister_trace_probe(struct trace_probe *tp)
+{
+	if (tp->call.name)
+		unregister_probe_event(tp);
+	__unregister_trace_probe(tp);
+	list_del(&tp->list);
+}
+
+/* Register a trace_probe and probe_event */
+static int register_trace_probe(struct trace_probe *tp)
+{
+	struct trace_probe *old_tp;
+	int ret;
+
+	mutex_lock(&probe_lock);
+
+	if (probe_is_return(tp))
+		ret = register_kretprobe(&tp->rp);
+	else
+		ret = register_kprobe(&tp->kp);
+
+	if (ret) {
+		pr_warning("Could not insert probe(%d)\n", ret);
+		if (ret == -EILSEQ) {
+			pr_warning("Probing address(0x%p) is not an "
+				   "instruction boundary.\n",
+				   probe_address(tp));
+			ret = -EINVAL;
+		}
+		goto end;
+	}
+	/* register as an event */
+	if (tp->call.name) {
+		old_tp = find_probe_event(tp->call.name);
+		if (old_tp) {
+			/* delete old event */
+			unregister_trace_probe(old_tp);
+			free_trace_probe(old_tp);
+		}
+		ret = register_probe_event(tp);
+		if (ret) {
+			pr_warning("Faild to register probe event(%d)\n", ret);
+			__unregister_trace_probe(tp);
+		}
+	}
+	list_add_tail(&tp->list, &probe_list);
+end:
+	mutex_unlock(&probe_lock);
+	return ret;
+}
+
+/* Split symbol and offset. */
+static int split_symbol_offset(char *symbol, long *offset)
+{
+	char *tmp;
+	int ret;
+
+	if (!offset)
+		return -EINVAL;
+
+	tmp = strchr(symbol, '+');
+	if (!tmp)
+		tmp = strchr(symbol, '-');
+
+	if (tmp) {
+		/* skip sign because strict_strtol doesn't accept '+' */
+		ret = strict_strtol(tmp + 1, 0, offset);
+		if (ret)
+			return ret;
+		if (*tmp == '-')
+			*offset = -(*offset);
+		*tmp = '\0';
+	} else
+		*offset = 0;
+	return 0;
+}
+
+#define PARAM_MAX_ARGS 16
+#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
+
+static int parse_trace_arg(char *arg, struct fetch_func *ff, int is_return)
+{
+	int ret = 0;
+	unsigned long param;
+	long offset;
+	char *tmp;
+
+	switch (arg[0]) {
+	case 'a':	/* argument */
+		ret = strict_strtoul(arg + 1, 10, &param);
+		if (ret || param > PARAM_MAX_ARGS)
+			ret = -EINVAL;
+		else {
+			ff->func = fetch_argument;
+			ff->data = (void *)param;
+		}
+		break;
+	case 'r':	/* retval or retaddr */
+		if (is_return && arg[1] == 'v') {
+			ff->func = fetch_retvalue;
+			ff->data = NULL;
+		} else if (is_return && arg[1] == 'a') {
+			ff->func = fetch_ip;
+			ff->data = NULL;
+		} else
+			ret = -EINVAL;
+		break;
+	case '%':	/* named register */
+		ret = regs_query_register_offset(arg + 1);
+		if (ret >= 0) {
+			ff->func = fetch_register;
+			ff->data = (void *)(unsigned long)ret;
+			ret = 0;
+		}
+		break;
+	case 's':	/* stack */
+		if (arg[1] == 'a') {
+			ff->func = fetch_stack_address;
+			ff->data = NULL;
+		} else {
+			ret = strict_strtoul(arg + 1, 10, &param);
+			if (ret || param > PARAM_MAX_STACK)
+				ret = -EINVAL;
+			else {
+				ff->func = fetch_stack;
+				ff->data = (void *)param;
+			}
+		}
+		break;
+	case '@':	/* memory or symbol */
+		if (isdigit(arg[1])) {
+			ret = strict_strtoul(arg + 1, 0, &param);
+			if (ret)
+				break;
+			ff->func = fetch_memory;
+			ff->data = (void *)param;
+		} else {
+			ret = split_symbol_offset(arg + 1, &offset);
+			if (ret)
+				break;
+			ff->data = alloc_symbol_cache(arg + 1,
+							      offset);
+			if (ff->data)
+				ff->func = fetch_symbol;
+			else
+				ret = -EINVAL;
+		}
+		break;
+	case '+':	/* indirect memory */
+	case '-':
+		tmp = strchr(arg, '(');
+		if (!tmp) {
+			ret = -EINVAL;
+			break;
+		}
+		*tmp = '\0';
+		ret = strict_strtol(arg + 1, 0, &offset);
+		if (ret)
+			break;
+		if (arg[0] == '-')
+			offset = -offset;
+		arg = tmp + 1;
+		tmp = strrchr(arg, ')');
+		if (tmp) {
+			struct indirect_fetch_data *id;
+			*tmp = '\0';
+			id = kzalloc(sizeof(struct indirect_fetch_data),
+				     GFP_KERNEL);
+			if (!id)
+				return -ENOMEM;
+			id->offset = offset;
+			ret = parse_trace_arg(arg, &id->orig, is_return);
+			if (ret)
+				kfree(id);
+			else {
+				ff->func = fetch_indirect;
+				ff->data = (void *)id;
+			}
+		} else
+			ret = -EINVAL;
+		break;
+	default:
+		/* TODO: support custom handler */
+		ret = -EINVAL;
+	}
+	return ret;
+}
+
+static int create_trace_probe(int argc, char **argv)
+{
+	/*
+	 * Argument syntax:
+	 *  - Add kprobe: p[:EVENT] SYMBOL[+OFFS|-OFFS]|ADDRESS [FETCHARGS]
+	 *  - Add kretprobe: r[:EVENT] SYMBOL[+0] [FETCHARGS]
+	 * Fetch args:
+	 *  aN	: fetch Nth of function argument. (N:0-)
+	 *  rv	: fetch return value
+	 *  ra	: fetch return address
+	 *  sa	: fetch stack address
+	 *  sN	: fetch Nth of stack (N:0-)
+	 *  @ADDR	: fetch memory at ADDR (ADDR should be in kernel)
+	 *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
+	 *  %REG	: fetch register REG
+	 * Indirect memory fetch:
+	 *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
+	 */
+	struct trace_probe *tp;
+	struct kprobe *kp;
+	int i, ret = 0;
+	int is_return = 0;
+	char *symbol = NULL, *event = NULL;
+	long offset = 0;
+	void *addr = NULL;
+
+	if (argc < 2)
+		return -EINVAL;
+
+	if (argv[0][0] == 'p')
+		is_return = 0;
+	else if (argv[0][0] == 'r')
+		is_return = 1;
+	else
+		return -EINVAL;
+
+	if (argv[0][1] == ':') {
+		event = &argv[0][2];
+		if (strlen(event) == 0) {
+			pr_info("Event name is not specifiled\n");
+			return -EINVAL;
+		}
+	}
+
+	if (isdigit(argv[1][0])) {
+		if (is_return)
+			return -EINVAL;
+		/* an address specified */
+		ret = strict_strtoul(&argv[0][2], 0, (unsigned long *)&addr);
+		if (ret)
+			return ret;
+	} else {
+		/* a symbol specified */
+		symbol = argv[1];
+		/* TODO: support .init module functions */
+		ret = split_symbol_offset(symbol, &offset);
+		if (ret)
+			return ret;
+		if (offset && is_return)
+			return -EINVAL;
+	}
+
+	/* setup a probe */
+	tp = alloc_trace_probe(symbol, event);
+	if (IS_ERR(tp))
+		return PTR_ERR(tp);
+
+	if (is_return) {
+		kp = &tp->rp.kp;
+		tp->rp.handler = kretprobe_trace_func;
+	} else {
+		kp = &tp->kp;
+		tp->kp.pre_handler = kprobe_trace_func;
+	}
+
+	if (tp->symbol) {
+		kp->symbol_name = tp->symbol;
+		kp->offset = offset;
+	} else
+		kp->addr = addr;
+
+	/* parse arguments */
+	argc -= 2; argv += 2; ret = 0;
+	for (i = 0; i < argc && i < TRACE_KPROBE_ARGS; i++) {
+		if (strlen(argv[i]) > MAX_ARGSTR_LEN) {
+			pr_info("Argument%d(%s) is too long.\n", i, argv[i]);
+			ret = -ENOSPC;
+			goto error;
+		}
+		ret = parse_trace_arg(argv[i], &tp->args[i], is_return);
+		if (ret)
+			goto error;
+	}
+	tp->nr_args = i;
+
+	ret = register_trace_probe(tp);
+	if (ret)
+		goto error;
+	return 0;
+
+error:
+	free_trace_probe(tp);
+	return ret;
+}
+
+static void cleanup_all_probes(void)
+{
+	struct trace_probe *tp;
+
+	mutex_lock(&probe_lock);
+	/* TODO: Use batch unregistration */
+	while (!list_empty(&probe_list)) {
+		tp = list_entry(probe_list.next, struct trace_probe, list);
+		unregister_trace_probe(tp);
+		free_trace_probe(tp);
+	}
+	mutex_unlock(&probe_lock);
+}
+
+
+/* Probes listing interfaces */
+static void *probes_seq_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&probe_lock);
+	return seq_list_start(&probe_list, *pos);
+}
+
+static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &probe_list, pos);
+}
+
+static void probes_seq_stop(struct seq_file *m, void *v)
+{
+	mutex_unlock(&probe_lock);
+}
+
+static int probes_seq_show(struct seq_file *m, void *v)
+{
+	struct trace_probe *tp = v;
+	int i, ret;
+	char buf[MAX_ARGSTR_LEN + 1];
+
+	seq_printf(m, "%c", probe_is_return(tp) ? 'r' : 'p');
+	if (tp->call.name)
+		seq_printf(m, ":%s", tp->call.name);
+
+	if (tp->symbol)
+		seq_printf(m, " %s%+ld", probe_symbol(tp), probe_offset(tp));
+	else
+		seq_printf(m, " 0x%p", probe_address(tp));
+
+	for (i = 0; i < tp->nr_args; i++) {
+		ret = trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
+		if (ret < 0) {
+			pr_warning("Argument%d decoding error(%d).\n", i, ret);
+			return ret;
+		}
+		seq_printf(m, " %s", buf);
+	}
+	seq_printf(m, "\n");
+	return 0;
+}
+
+static const struct seq_operations probes_seq_op = {
+	.start  = probes_seq_start,
+	.next   = probes_seq_next,
+	.stop   = probes_seq_stop,
+	.show   = probes_seq_show
+};
+
+static int probes_open(struct inode *inode, struct file *file)
+{
+	if ((file->f_mode & FMODE_WRITE) &&
+	    (file->f_flags & O_TRUNC))
+		cleanup_all_probes();
+
+	return seq_open(file, &probes_seq_op);
+}
+
+static int command_trace_probe(const char *buf)
+{
+	char **argv;
+	int argc = 0, ret = 0;
+
+	argv = argv_split(GFP_KERNEL, buf, &argc);
+	if (!argv)
+		return -ENOMEM;
+
+	if (argc)
+		ret = create_trace_probe(argc, argv);
+
+	argv_free(argv);
+	return ret;
+}
+
+#define WRITE_BUFSIZE 128
+
+static ssize_t probes_write(struct file *file, const char __user *buffer,
+			    size_t count, loff_t *ppos)
+{
+	char *kbuf, *tmp;
+	int ret;
+	size_t done;
+	size_t size;
+
+	kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	ret = done = 0;
+	while (done < count) {
+		size = count - done;
+		if (size >= WRITE_BUFSIZE)
+			size = WRITE_BUFSIZE - 1;
+		if (copy_from_user(kbuf, buffer + done, size)) {
+			ret = -EFAULT;
+			goto out;
+		}
+		kbuf[size] = '\0';
+		tmp = strchr(kbuf, '\n');
+		if (tmp) {
+			*tmp = '\0';
+			size = tmp - kbuf + 1;
+		} else if (done + size < count) {
+			pr_warning("Line length is too long: "
+				   "Should be less than %d.", WRITE_BUFSIZE);
+			ret = -EINVAL;
+			goto out;
+		}
+		done += size;
+		/* Remove comments */
+		tmp = strchr(kbuf, '#');
+		if (tmp)
+			*tmp = '\0';
+
+		ret = command_trace_probe(kbuf);
+		if (ret)
+			goto out;
+	}
+	ret = done;
+out:
+	kfree(kbuf);
+	return ret;
+}
+
+static const struct file_operations kprobe_events_ops = {
+	.owner          = THIS_MODULE,
+	.open           = probes_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+	.write		= probes_write,
+};
+
+/* Kprobe handler */
+static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
+{
+	struct trace_probe *tp = container_of(kp, struct trace_probe, kp);
+	struct kprobe_trace_entry *entry;
+	struct ring_buffer_event *event;
+	int size, i, pc;
+	unsigned long irq_flags;
+	struct ftrace_event_call *call = &event_kprobe;
+
+	if (&tp->call.name)
+		call = &tp->call;
+
+	local_save_flags(irq_flags);
+	pc = preempt_count();
+
+	size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
+
+	event = trace_current_buffer_lock_reserve(TRACE_KPROBE, size,
+						  irq_flags, pc);
+	if (!event)
+		return 0;
+
+	entry = ring_buffer_event_data(event);
+	entry->nargs = tp->nr_args;
+	entry->ip = (unsigned long)kp->addr;
+	for (i = 0; i < tp->nr_args; i++)
+		entry->args[i] = call_fetch(&tp->args[i], regs);
+
+	if (!filter_current_check_discard(call, entry, event))
+		trace_nowake_buffer_unlock_commit(event, irq_flags, pc);
+	return 0;
+}
+
+/* Kretprobe handler */
+static __kprobes int kretprobe_trace_func(struct kretprobe_instance *ri,
+					  struct pt_regs *regs)
+{
+	struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
+	struct kretprobe_trace_entry *entry;
+	struct ring_buffer_event *event;
+	int size, i, pc;
+	unsigned long irq_flags;
+	struct ftrace_event_call *call = &event_kretprobe;
+
+	if (&tp->call.name)
+		call = &tp->call;
+
+	local_save_flags(irq_flags);
+	pc = preempt_count();
+
+	size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
+
+	event = trace_current_buffer_lock_reserve(TRACE_KRETPROBE, size,
+						  irq_flags, pc);
+	if (!event)
+		return 0;
+
+	entry = ring_buffer_event_data(event);
+	entry->nargs = tp->nr_args;
+	entry->func = (unsigned long)probe_address(tp);
+	entry->ret_ip = (unsigned long)ri->ret_addr;
+	for (i = 0; i < tp->nr_args; i++)
+		entry->args[i] = call_fetch(&tp->args[i], regs);
+
+	if (!filter_current_check_discard(call, entry, event))
+		trace_nowake_buffer_unlock_commit(event, irq_flags, pc);
+
+	return 0;
+}
+
+/* Event entry printers */
+enum print_line_t
+print_kprobe_event(struct trace_iterator *iter, int flags)
+{
+	struct kprobe_trace_entry *field;
+	struct trace_seq *s = &iter->seq;
+	int i;
+
+	trace_assign_type(field, iter->ent);
+
+	if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
+		goto partial;
+
+	if (!trace_seq_puts(s, ":"))
+		goto partial;
+
+	for (i = 0; i < field->nargs; i++)
+		if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
+			goto partial;
+
+	if (!trace_seq_puts(s, "\n"))
+		goto partial;
+
+	return TRACE_TYPE_HANDLED;
+partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+enum print_line_t
+print_kretprobe_event(struct trace_iterator *iter, int flags)
+{
+	struct kretprobe_trace_entry *field;
+	struct trace_seq *s = &iter->seq;
+	int i;
+
+	trace_assign_type(field, iter->ent);
+
+	if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
+		goto partial;
+
+	if (!trace_seq_puts(s, " <- "))
+		goto partial;
+
+	if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
+		goto partial;
+
+	if (!trace_seq_puts(s, ":"))
+		goto partial;
+
+	for (i = 0; i < field->nargs; i++)
+		if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
+			goto partial;
+
+	if (!trace_seq_puts(s, "\n"))
+		goto partial;
+
+	return TRACE_TYPE_HANDLED;
+partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static struct trace_event kprobe_trace_event = {
+	.type	 	= TRACE_KPROBE,
+	.trace		= print_kprobe_event,
+};
+
+static struct trace_event kretprobe_trace_event = {
+	.type	 	= TRACE_KRETPROBE,
+	.trace		= print_kretprobe_event,
+};
+
+static int probe_event_enable(struct ftrace_event_call *call)
+{
+	struct trace_probe *tp = (struct trace_probe *)call->data;
+
+	if (probe_is_return(tp))
+		return enable_kretprobe(&tp->rp);
+	else
+		return enable_kprobe(&tp->kp);
+}
+
+static void probe_event_disable(struct ftrace_event_call *call)
+{
+	struct trace_probe *tp = (struct trace_probe *)call->data;
+
+	if (probe_is_return(tp))
+		disable_kretprobe(&tp->rp);
+	else
+		disable_kprobe(&tp->kp);
+}
+
+static int probe_event_raw_init(struct ftrace_event_call *event_call)
+{
+	INIT_LIST_HEAD(&event_call->fields);
+	init_preds(event_call);
+	return 0;
+}
+
+#undef DEFINE_FIELD
+#define DEFINE_FIELD(type, item, name, is_signed)			\
+	do {								\
+		ret = trace_define_field(event_call, #type, name,	\
+					 offsetof(typeof(field), item),	\
+					 sizeof(field.item), is_signed, \
+					 FILTER_OTHER);			\
+		if (ret)						\
+			return ret;					\
+	} while (0)
+
+static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
+{
+	int ret, i;
+	struct kprobe_trace_entry field;
+	char buf[MAX_ARGSTR_LEN + 1];
+	struct trace_probe *tp = (struct trace_probe *)event_call->data;
+
+	ret = trace_define_common_fields(event_call);
+	if (!ret)
+		return ret;
+
+	DEFINE_FIELD(unsigned long, ip, "ip", 0);
+	DEFINE_FIELD(int, nargs, "nargs", 1);
+	for (i = 0; i < tp->nr_args; i++) {
+		/* Set argN as a field */
+		sprintf(buf, "arg%d", i);
+		DEFINE_FIELD(unsigned long, args[i], buf, 0);
+		/* Set argument string as an alias field */
+		ret = trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
+		if (ret < 0)
+			return ret;
+		DEFINE_FIELD(unsigned long, args[i], buf, 0);
+	}
+	return 0;
+}
+
+static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
+{
+	int ret, i;
+	struct kretprobe_trace_entry field;
+	char buf[MAX_ARGSTR_LEN + 1];
+	struct trace_probe *tp = (struct trace_probe *)event_call->data;
+
+	ret = trace_define_common_fields(event_call);
+	if (!ret)
+		return ret;
+
+	DEFINE_FIELD(unsigned long, func, "func", 0);
+	DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
+	DEFINE_FIELD(int, nargs, "nargs", 1);
+	for (i = 0; i < tp->nr_args; i++) {
+		/* Set argN as a field */
+		sprintf(buf, "arg%d", i);
+		DEFINE_FIELD(unsigned long, args[i], buf, 0);
+		/* Set argument string as an alias field */
+		ret = trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
+		if (ret < 0)
+			return ret;
+		DEFINE_FIELD(unsigned long, args[i], buf, 0);
+	}
+	return 0;
+}
+
+static int __probe_event_show_format(struct trace_seq *s,
+				     struct trace_probe *tp, const char *fmt,
+				     const char *arg)
+{
+	int i, ret;
+	char buf[MAX_ARGSTR_LEN + 1];
+
+	/* Show aliases */
+	for (i = 0; i < tp->nr_args; i++) {
+		ret = trace_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
+		if (ret < 0)
+			return ret;
+		if (!trace_seq_printf(s, "\talias: %s;\toriginal: arg%d;\n",
+				      buf, i))
+			return 0;
+	}
+	/* Show format */
+	if (!trace_seq_printf(s, "\nprint fmt: \"%s", fmt))
+		return 0;
+
+	for (i = 0; i < tp->nr_args; i++)
+		if (!trace_seq_puts(s, " 0x%lx"))
+			return 0;
+
+	if (!trace_seq_printf(s, "\", %s", arg))
+		return 0;
+
+	for (i = 0; i < tp->nr_args; i++)
+		if (!trace_seq_printf(s, ", arg%d", i))
+			return 0;
+
+	return trace_seq_puts(s, "\n");
+}
+
+#undef SHOW_FIELD
+#define SHOW_FIELD(type, item, name)					\
+	do {								\
+		ret = trace_seq_printf(s, "\tfield: " #type " %s;\t"	\
+				"offset:%u;tsize:%u;\n", name,		\
+				(unsigned int)offsetof(typeof(field), item),\
+				(unsigned int)sizeof(type));		\
+		if (!ret)						\
+			return 0;					\
+	} while (0)
+
+static int kprobe_event_show_format(struct ftrace_event_call *call,
+				    struct trace_seq *s)
+{
+	struct kprobe_trace_entry field __attribute__((unused));
+	int ret, i;
+	char buf[8];
+	struct trace_probe *tp = (struct trace_probe *)call->data;
+
+	SHOW_FIELD(unsigned long, ip, "ip");
+	SHOW_FIELD(int, nargs, "nargs");
+
+	/* Show fields */
+	for (i = 0; i < tp->nr_args; i++) {
+		sprintf(buf, "arg%d", i);
+		SHOW_FIELD(unsigned long, args[i], buf);
+	}
+	trace_seq_puts(s, "\n");
+
+	return __probe_event_show_format(s, tp, "%lx:", "ip");
+}
+
+static int kretprobe_event_show_format(struct ftrace_event_call *call,
+				       struct trace_seq *s)
+{
+	struct kretprobe_trace_entry field __attribute__((unused));
+	int ret, i;
+	char buf[8];
+	struct trace_probe *tp = (struct trace_probe *)call->data;
+
+	SHOW_FIELD(unsigned long, func, "func");
+	SHOW_FIELD(unsigned long, ret_ip, "ret_ip");
+	SHOW_FIELD(int, nargs, "nargs");
+
+	/* Show fields */
+	for (i = 0; i < tp->nr_args; i++) {
+		sprintf(buf, "arg%d", i);
+		SHOW_FIELD(unsigned long, args[i], buf);
+	}
+	trace_seq_puts(s, "\n");
+
+	return __probe_event_show_format(s, tp, "%lx <- %lx:",
+					  "func, ret_ip");
+}
+
+static int register_probe_event(struct trace_probe *tp)
+{
+	struct ftrace_event_call *call = &tp->call;
+	int ret;
+
+	/* Initialize ftrace_event_call */
+	call->system = "kprobes";
+	if (probe_is_return(tp)) {
+		call->event = &kretprobe_trace_event;
+		call->id = TRACE_KRETPROBE;
+		call->raw_init = probe_event_raw_init;
+		call->show_format = kretprobe_event_show_format;
+		call->define_fields = kretprobe_event_define_fields;
+	} else {
+		call->event = &kprobe_trace_event;
+		call->id = TRACE_KPROBE;
+		call->raw_init = probe_event_raw_init;
+		call->show_format = kprobe_event_show_format;
+		call->define_fields = kprobe_event_define_fields;
+	}
+	call->enabled = 1;
+	call->regfunc = probe_event_enable;
+	call->unregfunc = probe_event_disable;
+	call->data = tp;
+	ret = trace_add_event_call(call);
+	if (ret)
+		pr_info("Failed to register kprobe event: %s\n", call->name);
+	return ret;
+}
+
+static void unregister_probe_event(struct trace_probe *tp)
+{
+	/*
+	 * Prevent to unregister event itself because the event is shared
+	 * among other probes.
+	 */
+	tp->call.event = NULL;
+	trace_remove_event_call(&tp->call);
+}
+
+/* Make a debugfs interface for controling probe points */
+static __init int init_kprobe_trace(void)
+{
+	struct dentry *d_tracer;
+	struct dentry *entry;
+	int ret;
+
+	ret = register_ftrace_event(&kprobe_trace_event);
+	if (!ret) {
+		pr_warning("Could not register kprobe_trace_event type.\n");
+		return 0;
+	}
+	ret = register_ftrace_event(&kretprobe_trace_event);
+	if (!ret) {
+		pr_warning("Could not register kretprobe_trace_event type.\n");
+		return 0;
+	}
+
+	d_tracer = tracing_init_dentry();
+	if (!d_tracer)
+		return 0;
+
+	entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
+				    NULL, &kprobe_events_ops);
+
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'kprobe_events' entry\n");
+	return 0;
+}
+fs_initcall(init_kprobe_trace);
+
+
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+
+static int kprobe_trace_selftest_target(int a1, int a2, int a3,
+					int a4, int a5, int a6)
+{
+	return a1 + a2 + a3 + a4 + a5 + a6;
+}
+
+static __init int kprobe_trace_self_tests_init(void)
+{
+	int ret;
+	int (*target)(int, int, int, int, int, int);
+
+	target = kprobe_trace_selftest_target;
+
+	pr_info("Testing kprobe tracing: ");
+
+	ret = command_trace_probe("p:testprobe kprobe_trace_selftest_target "
+				  "a1 a2 a3 a4 a5 a6");
+	if (WARN_ON_ONCE(ret))
+		pr_warning("error enabling function entry\n");
+
+	ret = command_trace_probe("r:testprobe2 kprobe_trace_selftest_target "
+				  "ra rv");
+	if (WARN_ON_ONCE(ret))
+		pr_warning("error enabling function return\n");
+
+	ret = target(1, 2, 3, 4, 5, 6);
+
+	cleanup_all_probes();
+
+	pr_cont("OK\n");
+	return 0;
+}
+
+late_initcall(kprobe_trace_self_tests_init);
+
+#endif