Merge branch 'perf-uprobes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull user-space probe instrumentation from Ingo Molnar:
 "The uprobes code originates from SystemTap and has been used for years
  in Fedora and RHEL kernels.  This version is much rewritten, reviews
  from PeterZ, Oleg and myself shaped the end result.

  This tree includes uprobes support in 'perf probe' - but SystemTap
  (and other tools) can take advantage of user probe points as well.

  Sample usage of uprobes via perf, for example to profile malloc()
  calls without modifying user-space binaries.

  First boot a new kernel with CONFIG_UPROBE_EVENT=y enabled.

  If you don't know which function you want to probe you can pick one
  from 'perf top' or can get a list all functions that can be probed
  within libc (binaries can be specified as well):

	$ perf probe -F -x /lib/libc.so.6

  To probe libc's malloc():

	$ perf probe -x /lib64/libc.so.6 malloc
	Added new event:
	probe_libc:malloc    (on 0x7eac0)

  You can now use it in all perf tools, such as:

	perf record -e probe_libc:malloc -aR sleep 1

  Make use of it to create a call graph (as the flat profile is going to
  look very boring):

	$ perf record -e probe_libc:malloc -gR make
	[ perf record: Woken up 173 times to write data ]
	[ perf record: Captured and wrote 44.190 MB perf.data (~1930712

	$ perf report | less

	  32.03%            git  libc-2.15.so   [.] malloc
	                    |
	                    --- malloc

	  29.49%            cc1  libc-2.15.so   [.] malloc
	                    |
	                    --- malloc
	                       |
	                       |--0.95%-- 0x208eb1000000000
	                       |
	                       |--0.63%-- htab_traverse_noresize

	  11.04%             as  libc-2.15.so   [.] malloc
	                     |
	                     --- malloc
	                        |

	   7.15%             ld  libc-2.15.so   [.] malloc
	                     |
	                     --- malloc
	                        |

	   5.07%             sh  libc-2.15.so   [.] malloc
	                     |
	                     --- malloc
	                        |
	   4.99%  python-config  libc-2.15.so   [.] malloc
	          |
	          --- malloc
	             |
	   4.54%           make  libc-2.15.so   [.] malloc
	                   |
	                   --- malloc
	                      |
	                      |--7.34%-- glob
	                      |          |
	                      |          |--93.18%-- 0x41588f
	                      |          |
	                      |           --6.82%-- glob
	                      |                     0x41588f

	   ...

  Or:

	$ perf report -g flat | less

	# Overhead        Command  Shared Object      Symbol
	# ........  .............  .............  ..........
	#
	  32.03%            git  libc-2.15.so   [.] malloc
	          27.19%
	              malloc

	  29.49%            cc1  libc-2.15.so   [.] malloc
	          24.77%
	              malloc

	  11.04%             as  libc-2.15.so   [.] malloc
	          11.02%
	              malloc

	   7.15%             ld  libc-2.15.so   [.] malloc
	           6.57%
	              malloc

	 ...

  The core uprobes design is fairly straightforward: uprobes probe
  points register themselves at (inode:offset) addresses of
  libraries/binaries, after which all existing (or new) vmas that map
  that address will have a software breakpoint injected at that address.
  vmas are COW-ed to preserve original content.  The probe points are
  kept in an rbtree.

  If user-space executes the probed inode:offset instruction address
  then an event is generated which can be recovered from the regular
  perf event channels and mmap-ed ring-buffer.

  Multiple probes at the same address are supported, they create a
  dynamic callback list of event consumers.

  The basic model is further complicated by the XOL speedup: the
  original instruction that is probed is copied (in an architecture
  specific fashion) and executed out of line when the probe triggers.
  The XOL area is a single vma per process, with a fixed number of
  entries (which limits probe execution parallelism).

  The API: uprobes are installed/removed via
  /sys/kernel/debug/tracing/uprobe_events, the API is integrated to
  align with the kprobes interface as much as possible, but is separate
  to it.

  Injecting a probe point is privileged operation, which can be relaxed
  by setting perf_paranoid to -1.

  You can use multiple probes as well and mix them with kprobes and
  regular PMU events or tracepoints, when instrumenting a task."

Fix up trivial conflicts in mm/memory.c due to previous cleanup of
unmap_single_vma().

* 'perf-uprobes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  perf probe: Detect probe target when m/x options are absent
  perf probe: Provide perf interface for uprobes
  tracing: Fix kconfig warning due to a typo
  tracing: Provide trace events interface for uprobes
  tracing: Extract out common code for kprobes/uprobes trace events
  tracing: Modify is_delete, is_return from int to bool
  uprobes/core: Decrement uprobe count before the pages are unmapped
  uprobes/core: Make background page replacement logic account for rss_stat counters
  uprobes/core: Optimize probe hits with the help of a counter
  uprobes/core: Allocate XOL slots for uprobes use
  uprobes/core: Handle breakpoint and singlestep exceptions
  uprobes/core: Rename bkpt to swbp
  uprobes/core: Make order of function parameters consistent across functions
  uprobes/core: Make macro names consistent
  uprobes: Update copyright notices
  uprobes/core: Move insn to arch specific structure
  uprobes/core: Remove uprobe_opcode_sz
  uprobes/core: Make instruction tables volatile
  uprobes: Move to kernel/events/
  uprobes/core: Clean up, refactor and improve the code
  ...

1 files changed, 788 insertions, 0 deletions

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
new file mode 100644
index 00000000000..2b36ac68549
--- /dev/null
+++ b/kernel/trace/trace_uprobe.c
@@ -0,0 +1,788 @@
+/*
+ * uprobes-based tracing events
+ *
+ * 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
+ *
+ * Copyright (C) IBM Corporation, 2010-2012
+ * Author:	Srikar Dronamraju <srikar@linux.vnet.ibm.com>
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/uprobes.h>
+#include <linux/namei.h>
+
+#include "trace_probe.h"
+
+#define UPROBE_EVENT_SYSTEM	"uprobes"
+
+/*
+ * uprobe event core functions
+ */
+struct trace_uprobe;
+struct uprobe_trace_consumer {
+	struct uprobe_consumer		cons;
+	struct trace_uprobe		*tu;
+};
+
+struct trace_uprobe {
+	struct list_head		list;
+	struct ftrace_event_class	class;
+	struct ftrace_event_call	call;
+	struct uprobe_trace_consumer	*consumer;
+	struct inode			*inode;
+	char				*filename;
+	unsigned long			offset;
+	unsigned long			nhit;
+	unsigned int			flags;	/* For TP_FLAG_* */
+	ssize_t				size;	/* trace entry size */
+	unsigned int			nr_args;
+	struct probe_arg		args[];
+};
+
+#define SIZEOF_TRACE_UPROBE(n)			\
+	(offsetof(struct trace_uprobe, args) +	\
+	(sizeof(struct probe_arg) * (n)))
+
+static int register_uprobe_event(struct trace_uprobe *tu);
+static void unregister_uprobe_event(struct trace_uprobe *tu);
+
+static DEFINE_MUTEX(uprobe_lock);
+static LIST_HEAD(uprobe_list);
+
+static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
+
+/*
+ * Allocate new trace_uprobe and initialize it (including uprobes).
+ */
+static struct trace_uprobe *
+alloc_trace_uprobe(const char *group, const char *event, int nargs)
+{
+	struct trace_uprobe *tu;
+
+	if (!event || !is_good_name(event))
+		return ERR_PTR(-EINVAL);
+
+	if (!group || !is_good_name(group))
+		return ERR_PTR(-EINVAL);
+
+	tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
+	if (!tu)
+		return ERR_PTR(-ENOMEM);
+
+	tu->call.class = &tu->class;
+	tu->call.name = kstrdup(event, GFP_KERNEL);
+	if (!tu->call.name)
+		goto error;
+
+	tu->class.system = kstrdup(group, GFP_KERNEL);
+	if (!tu->class.system)
+		goto error;
+
+	INIT_LIST_HEAD(&tu->list);
+	return tu;
+
+error:
+	kfree(tu->call.name);
+	kfree(tu);
+
+	return ERR_PTR(-ENOMEM);
+}
+
+static void free_trace_uprobe(struct trace_uprobe *tu)
+{
+	int i;
+
+	for (i = 0; i < tu->nr_args; i++)
+		traceprobe_free_probe_arg(&tu->args[i]);
+
+	iput(tu->inode);
+	kfree(tu->call.class->system);
+	kfree(tu->call.name);
+	kfree(tu->filename);
+	kfree(tu);
+}
+
+static struct trace_uprobe *find_probe_event(const char *event, const char *group)
+{
+	struct trace_uprobe *tu;
+
+	list_for_each_entry(tu, &uprobe_list, list)
+		if (strcmp(tu->call.name, event) == 0 &&
+		    strcmp(tu->call.class->system, group) == 0)
+			return tu;
+
+	return NULL;
+}
+
+/* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
+static void unregister_trace_uprobe(struct trace_uprobe *tu)
+{
+	list_del(&tu->list);
+	unregister_uprobe_event(tu);
+	free_trace_uprobe(tu);
+}
+
+/* Register a trace_uprobe and probe_event */
+static int register_trace_uprobe(struct trace_uprobe *tu)
+{
+	struct trace_uprobe *old_tp;
+	int ret;
+
+	mutex_lock(&uprobe_lock);
+
+	/* register as an event */
+	old_tp = find_probe_event(tu->call.name, tu->call.class->system);
+	if (old_tp)
+		/* delete old event */
+		unregister_trace_uprobe(old_tp);
+
+	ret = register_uprobe_event(tu);
+	if (ret) {
+		pr_warning("Failed to register probe event(%d)\n", ret);
+		goto end;
+	}
+
+	list_add_tail(&tu->list, &uprobe_list);
+
+end:
+	mutex_unlock(&uprobe_lock);
+
+	return ret;
+}
+
+/*
+ * Argument syntax:
+ *  - Add uprobe: p[:[GRP/]EVENT] PATH:SYMBOL[+offs] [FETCHARGS]
+ *
+ *  - Remove uprobe: -:[GRP/]EVENT
+ */
+static int create_trace_uprobe(int argc, char **argv)
+{
+	struct trace_uprobe *tu;
+	struct inode *inode;
+	char *arg, *event, *group, *filename;
+	char buf[MAX_EVENT_NAME_LEN];
+	struct path path;
+	unsigned long offset;
+	bool is_delete;
+	int i, ret;
+
+	inode = NULL;
+	ret = 0;
+	is_delete = false;
+	event = NULL;
+	group = NULL;
+
+	/* argc must be >= 1 */
+	if (argv[0][0] == '-')
+		is_delete = true;
+	else if (argv[0][0] != 'p') {
+		pr_info("Probe definition must be started with 'p', 'r' or" " '-'.\n");
+		return -EINVAL;
+	}
+
+	if (argv[0][1] == ':') {
+		event = &argv[0][2];
+		arg = strchr(event, '/');
+
+		if (arg) {
+			group = event;
+			event = arg + 1;
+			event[-1] = '\0';
+
+			if (strlen(group) == 0) {
+				pr_info("Group name is not specified\n");
+				return -EINVAL;
+			}
+		}
+		if (strlen(event) == 0) {
+			pr_info("Event name is not specified\n");
+			return -EINVAL;
+		}
+	}
+	if (!group)
+		group = UPROBE_EVENT_SYSTEM;
+
+	if (is_delete) {
+		if (!event) {
+			pr_info("Delete command needs an event name.\n");
+			return -EINVAL;
+		}
+		mutex_lock(&uprobe_lock);
+		tu = find_probe_event(event, group);
+
+		if (!tu) {
+			mutex_unlock(&uprobe_lock);
+			pr_info("Event %s/%s doesn't exist.\n", group, event);
+			return -ENOENT;
+		}
+		/* delete an event */
+		unregister_trace_uprobe(tu);
+		mutex_unlock(&uprobe_lock);
+		return 0;
+	}
+
+	if (argc < 2) {
+		pr_info("Probe point is not specified.\n");
+		return -EINVAL;
+	}
+	if (isdigit(argv[1][0])) {
+		pr_info("probe point must be have a filename.\n");
+		return -EINVAL;
+	}
+	arg = strchr(argv[1], ':');
+	if (!arg)
+		goto fail_address_parse;
+
+	*arg++ = '\0';
+	filename = argv[1];
+	ret = kern_path(filename, LOOKUP_FOLLOW, &path);
+	if (ret)
+		goto fail_address_parse;
+
+	ret = strict_strtoul(arg, 0, &offset);
+	if (ret)
+		goto fail_address_parse;
+
+	inode = igrab(path.dentry->d_inode);
+
+	argc -= 2;
+	argv += 2;
+
+	/* setup a probe */
+	if (!event) {
+		char *tail = strrchr(filename, '/');
+		char *ptr;
+
+		ptr = kstrdup((tail ? tail + 1 : filename), GFP_KERNEL);
+		if (!ptr) {
+			ret = -ENOMEM;
+			goto fail_address_parse;
+		}
+
+		tail = ptr;
+		ptr = strpbrk(tail, ".-_");
+		if (ptr)
+			*ptr = '\0';
+
+		snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
+		event = buf;
+		kfree(tail);
+	}
+
+	tu = alloc_trace_uprobe(group, event, argc);
+	if (IS_ERR(tu)) {
+		pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
+		ret = PTR_ERR(tu);
+		goto fail_address_parse;
+	}
+	tu->offset = offset;
+	tu->inode = inode;
+	tu->filename = kstrdup(filename, GFP_KERNEL);
+
+	if (!tu->filename) {
+		pr_info("Failed to allocate filename.\n");
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	/* parse arguments */
+	ret = 0;
+	for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+		/* Increment count for freeing args in error case */
+		tu->nr_args++;
+
+		/* Parse argument name */
+		arg = strchr(argv[i], '=');
+		if (arg) {
+			*arg++ = '\0';
+			tu->args[i].name = kstrdup(argv[i], GFP_KERNEL);
+		} else {
+			arg = argv[i];
+			/* If argument name is omitted, set "argN" */
+			snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
+			tu->args[i].name = kstrdup(buf, GFP_KERNEL);
+		}
+
+		if (!tu->args[i].name) {
+			pr_info("Failed to allocate argument[%d] name.\n", i);
+			ret = -ENOMEM;
+			goto error;
+		}
+
+		if (!is_good_name(tu->args[i].name)) {
+			pr_info("Invalid argument[%d] name: %s\n", i, tu->args[i].name);
+			ret = -EINVAL;
+			goto error;
+		}
+
+		if (traceprobe_conflict_field_name(tu->args[i].name, tu->args, i)) {
+			pr_info("Argument[%d] name '%s' conflicts with "
+				"another field.\n", i, argv[i]);
+			ret = -EINVAL;
+			goto error;
+		}
+
+		/* Parse fetch argument */
+		ret = traceprobe_parse_probe_arg(arg, &tu->size, &tu->args[i], false, false);
+		if (ret) {
+			pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
+			goto error;
+		}
+	}
+
+	ret = register_trace_uprobe(tu);
+	if (ret)
+		goto error;
+	return 0;
+
+error:
+	free_trace_uprobe(tu);
+	return ret;
+
+fail_address_parse:
+	if (inode)
+		iput(inode);
+
+	pr_info("Failed to parse address.\n");
+
+	return ret;
+}
+
+static void cleanup_all_probes(void)
+{
+	struct trace_uprobe *tu;
+
+	mutex_lock(&uprobe_lock);
+	while (!list_empty(&uprobe_list)) {
+		tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
+		unregister_trace_uprobe(tu);
+	}
+	mutex_unlock(&uprobe_lock);
+}
+
+/* Probes listing interfaces */
+static void *probes_seq_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&uprobe_lock);
+	return seq_list_start(&uprobe_list, *pos);
+}
+
+static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &uprobe_list, pos);
+}
+
+static void probes_seq_stop(struct seq_file *m, void *v)
+{
+	mutex_unlock(&uprobe_lock);
+}
+
+static int probes_seq_show(struct seq_file *m, void *v)
+{
+	struct trace_uprobe *tu = v;
+	int i;
+
+	seq_printf(m, "p:%s/%s", tu->call.class->system, tu->call.name);
+	seq_printf(m, " %s:0x%p", tu->filename, (void *)tu->offset);
+
+	for (i = 0; i < tu->nr_args; i++)
+		seq_printf(m, " %s=%s", tu->args[i].name, tu->args[i].comm);
+
+	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 ssize_t probes_write(struct file *file, const char __user *buffer,
+			    size_t count, loff_t *ppos)
+{
+	return traceprobe_probes_write(file, buffer, count, ppos, create_trace_uprobe);
+}
+
+static const struct file_operations uprobe_events_ops = {
+	.owner		= THIS_MODULE,
+	.open		= probes_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+	.write		= probes_write,
+};
+
+/* Probes profiling interfaces */
+static int probes_profile_seq_show(struct seq_file *m, void *v)
+{
+	struct trace_uprobe *tu = v;
+
+	seq_printf(m, "  %s %-44s %15lu\n", tu->filename, tu->call.name, tu->nhit);
+	return 0;
+}
+
+static const struct seq_operations profile_seq_op = {
+	.start	= probes_seq_start,
+	.next	= probes_seq_next,
+	.stop	= probes_seq_stop,
+	.show	= probes_profile_seq_show
+};
+
+static int profile_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &profile_seq_op);
+}
+
+static const struct file_operations uprobe_profile_ops = {
+	.owner		= THIS_MODULE,
+	.open		= profile_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+/* uprobe handler */
+static void uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
+{
+	struct uprobe_trace_entry_head *entry;
+	struct ring_buffer_event *event;
+	struct ring_buffer *buffer;
+	u8 *data;
+	int size, i, pc;
+	unsigned long irq_flags;
+	struct ftrace_event_call *call = &tu->call;
+
+	tu->nhit++;
+
+	local_save_flags(irq_flags);
+	pc = preempt_count();
+
+	size = sizeof(*entry) + tu->size;
+
+	event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
+						  size, irq_flags, pc);
+	if (!event)
+		return;
+
+	entry = ring_buffer_event_data(event);
+	entry->ip = uprobe_get_swbp_addr(task_pt_regs(current));
+	data = (u8 *)&entry[1];
+	for (i = 0; i < tu->nr_args; i++)
+		call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
+
+	if (!filter_current_check_discard(buffer, call, entry, event))
+		trace_buffer_unlock_commit(buffer, event, irq_flags, pc);
+}
+
+/* Event entry printers */
+static enum print_line_t
+print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
+{
+	struct uprobe_trace_entry_head *field;
+	struct trace_seq *s = &iter->seq;
+	struct trace_uprobe *tu;
+	u8 *data;
+	int i;
+
+	field = (struct uprobe_trace_entry_head *)iter->ent;
+	tu = container_of(event, struct trace_uprobe, call.event);
+
+	if (!trace_seq_printf(s, "%s: (", tu->call.name))
+		goto partial;
+
+	if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
+		goto partial;
+
+	if (!trace_seq_puts(s, ")"))
+		goto partial;
+
+	data = (u8 *)&field[1];
+	for (i = 0; i < tu->nr_args; i++) {
+		if (!tu->args[i].type->print(s, tu->args[i].name,
+					     data + tu->args[i].offset, field))
+			goto partial;
+	}
+
+	if (trace_seq_puts(s, "\n"))
+		return TRACE_TYPE_HANDLED;
+
+partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static int probe_event_enable(struct trace_uprobe *tu, int flag)
+{
+	struct uprobe_trace_consumer *utc;
+	int ret = 0;
+
+	if (!tu->inode || tu->consumer)
+		return -EINTR;
+
+	utc = kzalloc(sizeof(struct uprobe_trace_consumer), GFP_KERNEL);
+	if (!utc)
+		return -EINTR;
+
+	utc->cons.handler = uprobe_dispatcher;
+	utc->cons.filter = NULL;
+	ret = uprobe_register(tu->inode, tu->offset, &utc->cons);
+	if (ret) {
+		kfree(utc);
+		return ret;
+	}
+
+	tu->flags |= flag;
+	utc->tu = tu;
+	tu->consumer = utc;
+
+	return 0;
+}
+
+static void probe_event_disable(struct trace_uprobe *tu, int flag)
+{
+	if (!tu->inode || !tu->consumer)
+		return;
+
+	uprobe_unregister(tu->inode, tu->offset, &tu->consumer->cons);
+	tu->flags &= ~flag;
+	kfree(tu->consumer);
+	tu->consumer = NULL;
+}
+
+static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
+{
+	int ret, i;
+	struct uprobe_trace_entry_head field;
+	struct trace_uprobe *tu = (struct trace_uprobe *)event_call->data;
+
+	DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+	/* Set argument names as fields */
+	for (i = 0; i < tu->nr_args; i++) {
+		ret = trace_define_field(event_call, tu->args[i].type->fmttype,
+					 tu->args[i].name,
+					 sizeof(field) + tu->args[i].offset,
+					 tu->args[i].type->size,
+					 tu->args[i].type->is_signed,
+					 FILTER_OTHER);
+
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+#define LEN_OR_ZERO		(len ? len - pos : 0)
+static int __set_print_fmt(struct trace_uprobe *tu, char *buf, int len)
+{
+	const char *fmt, *arg;
+	int i;
+	int pos = 0;
+
+	fmt = "(%lx)";
+	arg = "REC->" FIELD_STRING_IP;
+
+	/* When len=0, we just calculate the needed length */
+
+	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
+
+	for (i = 0; i < tu->nr_args; i++) {
+		pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
+				tu->args[i].name, tu->args[i].type->fmt);
+	}
+
+	pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
+
+	for (i = 0; i < tu->nr_args; i++) {
+		pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
+				tu->args[i].name);
+	}
+
+	return pos;	/* return the length of print_fmt */
+}
+#undef LEN_OR_ZERO
+
+static int set_print_fmt(struct trace_uprobe *tu)
+{
+	char *print_fmt;
+	int len;
+
+	/* First: called with 0 length to calculate the needed length */
+	len = __set_print_fmt(tu, NULL, 0);
+	print_fmt = kmalloc(len + 1, GFP_KERNEL);
+	if (!print_fmt)
+		return -ENOMEM;
+
+	/* Second: actually write the @print_fmt */
+	__set_print_fmt(tu, print_fmt, len + 1);
+	tu->call.print_fmt = print_fmt;
+
+	return 0;
+}
+
+#ifdef CONFIG_PERF_EVENTS
+/* uprobe profile handler */
+static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
+{
+	struct ftrace_event_call *call = &tu->call;
+	struct uprobe_trace_entry_head *entry;
+	struct hlist_head *head;
+	u8 *data;
+	int size, __size, i;
+	int rctx;
+
+	__size = sizeof(*entry) + tu->size;
+	size = ALIGN(__size + sizeof(u32), sizeof(u64));
+	size -= sizeof(u32);
+	if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
+		return;
+
+	preempt_disable();
+
+	entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
+	if (!entry)
+		goto out;
+
+	entry->ip = uprobe_get_swbp_addr(task_pt_regs(current));
+	data = (u8 *)&entry[1];
+	for (i = 0; i < tu->nr_args; i++)
+		call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
+
+	head = this_cpu_ptr(call->perf_events);
+	perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
+
+ out:
+	preempt_enable();
+}
+#endif	/* CONFIG_PERF_EVENTS */
+
+static
+int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
+{
+	struct trace_uprobe *tu = (struct trace_uprobe *)event->data;
+
+	switch (type) {
+	case TRACE_REG_REGISTER:
+		return probe_event_enable(tu, TP_FLAG_TRACE);
+
+	case TRACE_REG_UNREGISTER:
+		probe_event_disable(tu, TP_FLAG_TRACE);
+		return 0;
+
+#ifdef CONFIG_PERF_EVENTS
+	case TRACE_REG_PERF_REGISTER:
+		return probe_event_enable(tu, TP_FLAG_PROFILE);
+
+	case TRACE_REG_PERF_UNREGISTER:
+		probe_event_disable(tu, TP_FLAG_PROFILE);
+		return 0;
+#endif
+	default:
+		return 0;
+	}
+	return 0;
+}
+
+static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
+{
+	struct uprobe_trace_consumer *utc;
+	struct trace_uprobe *tu;
+
+	utc = container_of(con, struct uprobe_trace_consumer, cons);
+	tu = utc->tu;
+	if (!tu || tu->consumer != utc)
+		return 0;
+
+	if (tu->flags & TP_FLAG_TRACE)
+		uprobe_trace_func(tu, regs);
+
+#ifdef CONFIG_PERF_EVENTS
+	if (tu->flags & TP_FLAG_PROFILE)
+		uprobe_perf_func(tu, regs);
+#endif
+	return 0;
+}
+
+static struct trace_event_functions uprobe_funcs = {
+	.trace		= print_uprobe_event
+};
+
+static int register_uprobe_event(struct trace_uprobe *tu)
+{
+	struct ftrace_event_call *call = &tu->call;
+	int ret;
+
+	/* Initialize ftrace_event_call */
+	INIT_LIST_HEAD(&call->class->fields);
+	call->event.funcs = &uprobe_funcs;
+	call->class->define_fields = uprobe_event_define_fields;
+
+	if (set_print_fmt(tu) < 0)
+		return -ENOMEM;
+
+	ret = register_ftrace_event(&call->event);
+	if (!ret) {
+		kfree(call->print_fmt);
+		return -ENODEV;
+	}
+	call->flags = 0;
+	call->class->reg = trace_uprobe_register;
+	call->data = tu;
+	ret = trace_add_event_call(call);
+
+	if (ret) {
+		pr_info("Failed to register uprobe event: %s\n", call->name);
+		kfree(call->print_fmt);
+		unregister_ftrace_event(&call->event);
+	}
+
+	return ret;
+}
+
+static void unregister_uprobe_event(struct trace_uprobe *tu)
+{
+	/* tu->event is unregistered in trace_remove_event_call() */
+	trace_remove_event_call(&tu->call);
+	kfree(tu->call.print_fmt);
+	tu->call.print_fmt = NULL;
+}
+
+/* Make a trace interface for controling probe points */
+static __init int init_uprobe_trace(void)
+{
+	struct dentry *d_tracer;
+
+	d_tracer = tracing_init_dentry();
+	if (!d_tracer)
+		return 0;
+
+	trace_create_file("uprobe_events", 0644, d_tracer,
+				    NULL, &uprobe_events_ops);
+	/* Profile interface */
+	trace_create_file("uprobe_profile", 0444, d_tracer,
+				    NULL, &uprobe_profile_ops);
+	return 0;
+}
+
+fs_initcall(init_uprobe_trace);