Initial import

1 files changed, 1336 insertions, 0 deletions

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
new file mode 100644
index 000000000..6dd022c7b
--- /dev/null
+++ b/kernel/trace/trace_uprobe.c
@@ -0,0 +1,1336 @@
+/*
+ * 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 <linux/string.h>
+
+#include "trace_probe.h"
+
+#define UPROBE_EVENT_SYSTEM	"uprobes"
+
+struct uprobe_trace_entry_head {
+	struct trace_entry	ent;
+	unsigned long		vaddr[];
+};
+
+#define SIZEOF_TRACE_ENTRY(is_return)			\
+	(sizeof(struct uprobe_trace_entry_head) +	\
+	 sizeof(unsigned long) * (is_return ? 2 : 1))
+
+#define DATAOF_TRACE_ENTRY(entry, is_return)		\
+	((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))
+
+struct trace_uprobe_filter {
+	rwlock_t		rwlock;
+	int			nr_systemwide;
+	struct list_head	perf_events;
+};
+
+/*
+ * uprobe event core functions
+ */
+struct trace_uprobe {
+	struct list_head		list;
+	struct trace_uprobe_filter	filter;
+	struct uprobe_consumer		consumer;
+	struct inode			*inode;
+	char				*filename;
+	unsigned long			offset;
+	unsigned long			nhit;
+	struct trace_probe		tp;
+};
+
+#define SIZEOF_TRACE_UPROBE(n)				\
+	(offsetof(struct trace_uprobe, tp.args) +	\
+	(sizeof(struct probe_arg) * (n)))
+
+static int register_uprobe_event(struct trace_uprobe *tu);
+static int unregister_uprobe_event(struct trace_uprobe *tu);
+
+static DEFINE_MUTEX(uprobe_lock);
+static LIST_HEAD(uprobe_list);
+
+struct uprobe_dispatch_data {
+	struct trace_uprobe	*tu;
+	unsigned long		bp_addr;
+};
+
+static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
+static int uretprobe_dispatcher(struct uprobe_consumer *con,
+				unsigned long func, struct pt_regs *regs);
+
+#ifdef CONFIG_STACK_GROWSUP
+static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
+{
+	return addr - (n * sizeof(long));
+}
+#else
+static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
+{
+	return addr + (n * sizeof(long));
+}
+#endif
+
+static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
+{
+	unsigned long ret;
+	unsigned long addr = user_stack_pointer(regs);
+
+	addr = adjust_stack_addr(addr, n);
+
+	if (copy_from_user(&ret, (void __force __user *) addr, sizeof(ret)))
+		return 0;
+
+	return ret;
+}
+
+/*
+ * Uprobes-specific fetch functions
+ */
+#define DEFINE_FETCH_stack(type)					\
+static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,		\
+					 void *offset, void *dest)	\
+{									\
+	*(type *)dest = (type)get_user_stack_nth(regs,			\
+					      ((unsigned long)offset)); \
+}
+DEFINE_BASIC_FETCH_FUNCS(stack)
+/* No string on the stack entry */
+#define fetch_stack_string	NULL
+#define fetch_stack_string_size	NULL
+
+#define DEFINE_FETCH_memory(type)					\
+static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,		\
+					  void *addr, void *dest)	\
+{									\
+	type retval;							\
+	void __user *vaddr = (void __force __user *) addr;		\
+									\
+	if (copy_from_user(&retval, vaddr, sizeof(type)))		\
+		*(type *)dest = 0;					\
+	else								\
+		*(type *) dest = retval;				\
+}
+DEFINE_BASIC_FETCH_FUNCS(memory)
+/*
+ * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
+ * length and relative data location.
+ */
+static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
+					    void *addr, void *dest)
+{
+	long ret;
+	u32 rloc = *(u32 *)dest;
+	int maxlen  = get_rloc_len(rloc);
+	u8 *dst = get_rloc_data(dest);
+	void __user *src = (void __force __user *) addr;
+
+	if (!maxlen)
+		return;
+
+	ret = strncpy_from_user(dst, src, maxlen);
+
+	if (ret < 0) {	/* Failed to fetch string */
+		((u8 *)get_rloc_data(dest))[0] = '\0';
+		*(u32 *)dest = make_data_rloc(0, get_rloc_offs(rloc));
+	} else {
+		*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(rloc));
+	}
+}
+
+static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
+						 void *addr, void *dest)
+{
+	int len;
+	void __user *vaddr = (void __force __user *) addr;
+
+	len = strnlen_user(vaddr, MAX_STRING_SIZE);
+
+	if (len == 0 || len > MAX_STRING_SIZE)  /* Failed to check length */
+		*(u32 *)dest = 0;
+	else
+		*(u32 *)dest = len;
+}
+
+static unsigned long translate_user_vaddr(void *file_offset)
+{
+	unsigned long base_addr;
+	struct uprobe_dispatch_data *udd;
+
+	udd = (void *) current->utask->vaddr;
+
+	base_addr = udd->bp_addr - udd->tu->offset;
+	return base_addr + (unsigned long)file_offset;
+}
+
+#define DEFINE_FETCH_file_offset(type)					\
+static void FETCH_FUNC_NAME(file_offset, type)(struct pt_regs *regs,	\
+					       void *offset, void *dest)\
+{									\
+	void *vaddr = (void *)translate_user_vaddr(offset);		\
+									\
+	FETCH_FUNC_NAME(memory, type)(regs, vaddr, dest);		\
+}
+DEFINE_BASIC_FETCH_FUNCS(file_offset)
+DEFINE_FETCH_file_offset(string)
+DEFINE_FETCH_file_offset(string_size)
+
+/* Fetch type information table */
+static const struct fetch_type uprobes_fetch_type_table[] = {
+	/* Special types */
+	[FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
+					sizeof(u32), 1, "__data_loc char[]"),
+	[FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
+					string_size, sizeof(u32), 0, "u32"),
+	/* Basic types */
+	ASSIGN_FETCH_TYPE(u8,  u8,  0),
+	ASSIGN_FETCH_TYPE(u16, u16, 0),
+	ASSIGN_FETCH_TYPE(u32, u32, 0),
+	ASSIGN_FETCH_TYPE(u64, u64, 0),
+	ASSIGN_FETCH_TYPE(s8,  u8,  1),
+	ASSIGN_FETCH_TYPE(s16, u16, 1),
+	ASSIGN_FETCH_TYPE(s32, u32, 1),
+	ASSIGN_FETCH_TYPE(s64, u64, 1),
+
+	ASSIGN_FETCH_TYPE_END
+};
+
+static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
+{
+	rwlock_init(&filter->rwlock);
+	filter->nr_systemwide = 0;
+	INIT_LIST_HEAD(&filter->perf_events);
+}
+
+static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
+{
+	return !filter->nr_systemwide && list_empty(&filter->perf_events);
+}
+
+static inline bool is_ret_probe(struct trace_uprobe *tu)
+{
+	return tu->consumer.ret_handler != NULL;
+}
+
+/*
+ * Allocate new trace_uprobe and initialize it (including uprobes).
+ */
+static struct trace_uprobe *
+alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
+{
+	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->tp.call.class = &tu->tp.class;
+	tu->tp.call.name = kstrdup(event, GFP_KERNEL);
+	if (!tu->tp.call.name)
+		goto error;
+
+	tu->tp.class.system = kstrdup(group, GFP_KERNEL);
+	if (!tu->tp.class.system)
+		goto error;
+
+	INIT_LIST_HEAD(&tu->list);
+	INIT_LIST_HEAD(&tu->tp.files);
+	tu->consumer.handler = uprobe_dispatcher;
+	if (is_ret)
+		tu->consumer.ret_handler = uretprobe_dispatcher;
+	init_trace_uprobe_filter(&tu->filter);
+	return tu;
+
+error:
+	kfree(tu->tp.call.name);
+	kfree(tu);
+
+	return ERR_PTR(-ENOMEM);
+}
+
+static void free_trace_uprobe(struct trace_uprobe *tu)
+{
+	int i;
+
+	for (i = 0; i < tu->tp.nr_args; i++)
+		traceprobe_free_probe_arg(&tu->tp.args[i]);
+
+	iput(tu->inode);
+	kfree(tu->tp.call.class->system);
+	kfree(tu->tp.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(ftrace_event_name(&tu->tp.call), event) == 0 &&
+		    strcmp(tu->tp.call.class->system, group) == 0)
+			return tu;
+
+	return NULL;
+}
+
+/* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
+static int unregister_trace_uprobe(struct trace_uprobe *tu)
+{
+	int ret;
+
+	ret = unregister_uprobe_event(tu);
+	if (ret)
+		return ret;
+
+	list_del(&tu->list);
+	free_trace_uprobe(tu);
+	return 0;
+}
+
+/* Register a trace_uprobe and probe_event */
+static int register_trace_uprobe(struct trace_uprobe *tu)
+{
+	struct trace_uprobe *old_tu;
+	int ret;
+
+	mutex_lock(&uprobe_lock);
+
+	/* register as an event */
+	old_tu = find_probe_event(ftrace_event_name(&tu->tp.call),
+			tu->tp.call.class->system);
+	if (old_tu) {
+		/* delete old event */
+		ret = unregister_trace_uprobe(old_tu);
+		if (ret)
+			goto end;
+	}
+
+	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|r[:[GRP/]EVENT] PATH:OFFSET [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, is_return;
+	int i, ret;
+
+	inode = NULL;
+	ret = 0;
+	is_delete = false;
+	is_return = false;
+	event = NULL;
+	group = NULL;
+
+	/* argc must be >= 1 */
+	if (argv[0][0] == '-')
+		is_delete = true;
+	else if (argv[0][0] == 'r')
+		is_return = 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) {
+		int ret;
+
+		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 */
+		ret = unregister_trace_uprobe(tu);
+		mutex_unlock(&uprobe_lock);
+		return ret;
+	}
+
+	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) {
+		ret = -EINVAL;
+		goto fail_address_parse;
+	}
+
+	*arg++ = '\0';
+	filename = argv[1];
+	ret = kern_path(filename, LOOKUP_FOLLOW, &path);
+	if (ret)
+		goto fail_address_parse;
+
+	inode = igrab(d_inode(path.dentry));
+	path_put(&path);
+
+	if (!inode || !S_ISREG(inode->i_mode)) {
+		ret = -EINVAL;
+		goto fail_address_parse;
+	}
+
+	ret = kstrtoul(arg, 0, &offset);
+	if (ret)
+		goto fail_address_parse;
+
+	argc -= 2;
+	argv += 2;
+
+	/* setup a probe */
+	if (!event) {
+		char *tail;
+		char *ptr;
+
+		tail = kstrdup(kbasename(filename), GFP_KERNEL);
+		if (!tail) {
+			ret = -ENOMEM;
+			goto fail_address_parse;
+		}
+
+		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, is_return);
+	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++) {
+		struct probe_arg *parg = &tu->tp.args[i];
+
+		/* Increment count for freeing args in error case */
+		tu->tp.nr_args++;
+
+		/* Parse argument name */
+		arg = strchr(argv[i], '=');
+		if (arg) {
+			*arg++ = '\0';
+			parg->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);
+			parg->name = kstrdup(buf, GFP_KERNEL);
+		}
+
+		if (!parg->name) {
+			pr_info("Failed to allocate argument[%d] name.\n", i);
+			ret = -ENOMEM;
+			goto error;
+		}
+
+		if (!is_good_name(parg->name)) {
+			pr_info("Invalid argument[%d] name: %s\n", i, parg->name);
+			ret = -EINVAL;
+			goto error;
+		}
+
+		if (traceprobe_conflict_field_name(parg->name, tu->tp.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->tp.size, parg,
+						 is_return, false,
+						 uprobes_fetch_type_table);
+		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:
+	iput(inode);
+
+	pr_info("Failed to parse address or file.\n");
+
+	return ret;
+}
+
+static int cleanup_all_probes(void)
+{
+	struct trace_uprobe *tu;
+	int ret = 0;
+
+	mutex_lock(&uprobe_lock);
+	while (!list_empty(&uprobe_list)) {
+		tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
+		ret = unregister_trace_uprobe(tu);
+		if (ret)
+			break;
+	}
+	mutex_unlock(&uprobe_lock);
+	return ret;
+}
+
+/* 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;
+	char c = is_ret_probe(tu) ? 'r' : 'p';
+	int i;
+
+	seq_printf(m, "%c:%s/%s", c, tu->tp.call.class->system,
+			ftrace_event_name(&tu->tp.call));
+	seq_printf(m, " %s:0x%p", tu->filename, (void *)tu->offset);
+
+	for (i = 0; i < tu->tp.nr_args; i++)
+		seq_printf(m, " %s=%s", tu->tp.args[i].name, tu->tp.args[i].comm);
+
+	seq_putc(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)
+{
+	int ret;
+
+	if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
+		ret = cleanup_all_probes();
+		if (ret)
+			return ret;
+	}
+
+	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,
+			ftrace_event_name(&tu->tp.call), 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,
+};
+
+struct uprobe_cpu_buffer {
+	struct mutex mutex;
+	void *buf;
+};
+static struct uprobe_cpu_buffer __percpu *uprobe_cpu_buffer;
+static int uprobe_buffer_refcnt;
+
+static int uprobe_buffer_init(void)
+{
+	int cpu, err_cpu;
+
+	uprobe_cpu_buffer = alloc_percpu(struct uprobe_cpu_buffer);
+	if (uprobe_cpu_buffer == NULL)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		struct page *p = alloc_pages_node(cpu_to_node(cpu),
+						  GFP_KERNEL, 0);
+		if (p == NULL) {
+			err_cpu = cpu;
+			goto err;
+		}
+		per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf = page_address(p);
+		mutex_init(&per_cpu_ptr(uprobe_cpu_buffer, cpu)->mutex);
+	}
+
+	return 0;
+
+err:
+	for_each_possible_cpu(cpu) {
+		if (cpu == err_cpu)
+			break;
+		free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf);
+	}
+
+	free_percpu(uprobe_cpu_buffer);
+	return -ENOMEM;
+}
+
+static int uprobe_buffer_enable(void)
+{
+	int ret = 0;
+
+	BUG_ON(!mutex_is_locked(&event_mutex));
+
+	if (uprobe_buffer_refcnt++ == 0) {
+		ret = uprobe_buffer_init();
+		if (ret < 0)
+			uprobe_buffer_refcnt--;
+	}
+
+	return ret;
+}
+
+static void uprobe_buffer_disable(void)
+{
+	int cpu;
+
+	BUG_ON(!mutex_is_locked(&event_mutex));
+
+	if (--uprobe_buffer_refcnt == 0) {
+		for_each_possible_cpu(cpu)
+			free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer,
+							     cpu)->buf);
+
+		free_percpu(uprobe_cpu_buffer);
+		uprobe_cpu_buffer = NULL;
+	}
+}
+
+static struct uprobe_cpu_buffer *uprobe_buffer_get(void)
+{
+	struct uprobe_cpu_buffer *ucb;
+	int cpu;
+
+	cpu = raw_smp_processor_id();
+	ucb = per_cpu_ptr(uprobe_cpu_buffer, cpu);
+
+	/*
+	 * Use per-cpu buffers for fastest access, but we might migrate
+	 * so the mutex makes sure we have sole access to it.
+	 */
+	mutex_lock(&ucb->mutex);
+
+	return ucb;
+}
+
+static void uprobe_buffer_put(struct uprobe_cpu_buffer *ucb)
+{
+	mutex_unlock(&ucb->mutex);
+}
+
+static void __uprobe_trace_func(struct trace_uprobe *tu,
+				unsigned long func, struct pt_regs *regs,
+				struct uprobe_cpu_buffer *ucb, int dsize,
+				struct ftrace_event_file *ftrace_file)
+{
+	struct uprobe_trace_entry_head *entry;
+	struct ring_buffer_event *event;
+	struct ring_buffer *buffer;
+	void *data;
+	int size, esize;
+	struct ftrace_event_call *call = &tu->tp.call;
+
+	WARN_ON(call != ftrace_file->event_call);
+
+	if (WARN_ON_ONCE(tu->tp.size + dsize > PAGE_SIZE))
+		return;
+
+	if (ftrace_trigger_soft_disabled(ftrace_file))
+		return;
+
+	esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
+	size = esize + tu->tp.size + dsize;
+	event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
+						call->event.type, size, 0, 0);
+	if (!event)
+		return;
+
+	entry = ring_buffer_event_data(event);
+	if (is_ret_probe(tu)) {
+		entry->vaddr[0] = func;
+		entry->vaddr[1] = instruction_pointer(regs);
+		data = DATAOF_TRACE_ENTRY(entry, true);
+	} else {
+		entry->vaddr[0] = instruction_pointer(regs);
+		data = DATAOF_TRACE_ENTRY(entry, false);
+	}
+
+	memcpy(data, ucb->buf, tu->tp.size + dsize);
+
+	event_trigger_unlock_commit(ftrace_file, buffer, event, entry, 0, 0);
+}
+
+/* uprobe handler */
+static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,
+			     struct uprobe_cpu_buffer *ucb, int dsize)
+{
+	struct event_file_link *link;
+
+	if (is_ret_probe(tu))
+		return 0;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(link, &tu->tp.files, list)
+		__uprobe_trace_func(tu, 0, regs, ucb, dsize, link->file);
+	rcu_read_unlock();
+
+	return 0;
+}
+
+static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
+				 struct pt_regs *regs,
+				 struct uprobe_cpu_buffer *ucb, int dsize)
+{
+	struct event_file_link *link;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(link, &tu->tp.files, list)
+		__uprobe_trace_func(tu, func, regs, ucb, dsize, link->file);
+	rcu_read_unlock();
+}
+
+/* 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 *entry;
+	struct trace_seq *s = &iter->seq;
+	struct trace_uprobe *tu;
+	u8 *data;
+	int i;
+
+	entry = (struct uprobe_trace_entry_head *)iter->ent;
+	tu = container_of(event, struct trace_uprobe, tp.call.event);
+
+	if (is_ret_probe(tu)) {
+		trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
+				 ftrace_event_name(&tu->tp.call),
+				 entry->vaddr[1], entry->vaddr[0]);
+		data = DATAOF_TRACE_ENTRY(entry, true);
+	} else {
+		trace_seq_printf(s, "%s: (0x%lx)",
+				 ftrace_event_name(&tu->tp.call),
+				 entry->vaddr[0]);
+		data = DATAOF_TRACE_ENTRY(entry, false);
+	}
+
+	for (i = 0; i < tu->tp.nr_args; i++) {
+		struct probe_arg *parg = &tu->tp.args[i];
+
+		if (!parg->type->print(s, parg->name, data + parg->offset, entry))
+			goto out;
+	}
+
+	trace_seq_putc(s, '\n');
+
+ out:
+	return trace_handle_return(s);
+}
+
+typedef bool (*filter_func_t)(struct uprobe_consumer *self,
+				enum uprobe_filter_ctx ctx,
+				struct mm_struct *mm);
+
+static int
+probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
+		   filter_func_t filter)
+{
+	bool enabled = trace_probe_is_enabled(&tu->tp);
+	struct event_file_link *link = NULL;
+	int ret;
+
+	if (file) {
+		if (tu->tp.flags & TP_FLAG_PROFILE)
+			return -EINTR;
+
+		link = kmalloc(sizeof(*link), GFP_KERNEL);
+		if (!link)
+			return -ENOMEM;
+
+		link->file = file;
+		list_add_tail_rcu(&link->list, &tu->tp.files);
+
+		tu->tp.flags |= TP_FLAG_TRACE;
+	} else {
+		if (tu->tp.flags & TP_FLAG_TRACE)
+			return -EINTR;
+
+		tu->tp.flags |= TP_FLAG_PROFILE;
+	}
+
+	WARN_ON(!uprobe_filter_is_empty(&tu->filter));
+
+	if (enabled)
+		return 0;
+
+	ret = uprobe_buffer_enable();
+	if (ret)
+		goto err_flags;
+
+	tu->consumer.filter = filter;
+	ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
+	if (ret)
+		goto err_buffer;
+
+	return 0;
+
+ err_buffer:
+	uprobe_buffer_disable();
+
+ err_flags:
+	if (file) {
+		list_del(&link->list);
+		kfree(link);
+		tu->tp.flags &= ~TP_FLAG_TRACE;
+	} else {
+		tu->tp.flags &= ~TP_FLAG_PROFILE;
+	}
+	return ret;
+}
+
+static void
+probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
+{
+	if (!trace_probe_is_enabled(&tu->tp))
+		return;
+
+	if (file) {
+		struct event_file_link *link;
+
+		link = find_event_file_link(&tu->tp, file);
+		if (!link)
+			return;
+
+		list_del_rcu(&link->list);
+		/* synchronize with u{,ret}probe_trace_func */
+		synchronize_sched();
+		kfree(link);
+
+		if (!list_empty(&tu->tp.files))
+			return;
+	}
+
+	WARN_ON(!uprobe_filter_is_empty(&tu->filter));
+
+	uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
+	tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
+
+	uprobe_buffer_disable();
+}
+
+static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
+{
+	int ret, i, size;
+	struct uprobe_trace_entry_head field;
+	struct trace_uprobe *tu = event_call->data;
+
+	if (is_ret_probe(tu)) {
+		DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_FUNC, 0);
+		DEFINE_FIELD(unsigned long, vaddr[1], FIELD_STRING_RETIP, 0);
+		size = SIZEOF_TRACE_ENTRY(true);
+	} else {
+		DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
+		size = SIZEOF_TRACE_ENTRY(false);
+	}
+	/* Set argument names as fields */
+	for (i = 0; i < tu->tp.nr_args; i++) {
+		struct probe_arg *parg = &tu->tp.args[i];
+
+		ret = trace_define_field(event_call, parg->type->fmttype,
+					 parg->name, size + parg->offset,
+					 parg->type->size, parg->type->is_signed,
+					 FILTER_OTHER);
+
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+#ifdef CONFIG_PERF_EVENTS
+static bool
+__uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
+{
+	struct perf_event *event;
+
+	if (filter->nr_systemwide)
+		return true;
+
+	list_for_each_entry(event, &filter->perf_events, hw.tp_list) {
+		if (event->hw.target->mm == mm)
+			return true;
+	}
+
+	return false;
+}
+
+static inline bool
+uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
+{
+	return __uprobe_perf_filter(&tu->filter, event->hw.target->mm);
+}
+
+static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
+{
+	bool done;
+
+	write_lock(&tu->filter.rwlock);
+	if (event->hw.target) {
+		list_del(&event->hw.tp_list);
+		done = tu->filter.nr_systemwide ||
+			(event->hw.target->flags & PF_EXITING) ||
+			uprobe_filter_event(tu, event);
+	} else {
+		tu->filter.nr_systemwide--;
+		done = tu->filter.nr_systemwide;
+	}
+	write_unlock(&tu->filter.rwlock);
+
+	if (!done)
+		return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
+
+	return 0;
+}
+
+static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
+{
+	bool done;
+	int err;
+
+	write_lock(&tu->filter.rwlock);
+	if (event->hw.target) {
+		/*
+		 * event->parent != NULL means copy_process(), we can avoid
+		 * uprobe_apply(). current->mm must be probed and we can rely
+		 * on dup_mmap() which preserves the already installed bp's.
+		 *
+		 * attr.enable_on_exec means that exec/mmap will install the
+		 * breakpoints we need.
+		 */
+		done = tu->filter.nr_systemwide ||
+			event->parent || event->attr.enable_on_exec ||
+			uprobe_filter_event(tu, event);
+		list_add(&event->hw.tp_list, &tu->filter.perf_events);
+	} else {
+		done = tu->filter.nr_systemwide;
+		tu->filter.nr_systemwide++;
+	}
+	write_unlock(&tu->filter.rwlock);
+
+	err = 0;
+	if (!done) {
+		err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
+		if (err)
+			uprobe_perf_close(tu, event);
+	}
+	return err;
+}
+
+static bool uprobe_perf_filter(struct uprobe_consumer *uc,
+				enum uprobe_filter_ctx ctx, struct mm_struct *mm)
+{
+	struct trace_uprobe *tu;
+	int ret;
+
+	tu = container_of(uc, struct trace_uprobe, consumer);
+	read_lock(&tu->filter.rwlock);
+	ret = __uprobe_perf_filter(&tu->filter, mm);
+	read_unlock(&tu->filter.rwlock);
+
+	return ret;
+}
+
+static void __uprobe_perf_func(struct trace_uprobe *tu,
+			       unsigned long func, struct pt_regs *regs,
+			       struct uprobe_cpu_buffer *ucb, int dsize)
+{
+	struct ftrace_event_call *call = &tu->tp.call;
+	struct uprobe_trace_entry_head *entry;
+	struct hlist_head *head;
+	void *data;
+	int size, esize;
+	int rctx;
+
+	esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
+
+	size = esize + tu->tp.size + dsize;
+	size = ALIGN(size + sizeof(u32), sizeof(u64)) - sizeof(u32);
+	if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
+		return;
+
+	preempt_disable();
+	head = this_cpu_ptr(call->perf_events);
+	if (hlist_empty(head))
+		goto out;
+
+	entry = perf_trace_buf_prepare(size, call->event.type, NULL, &rctx);
+	if (!entry)
+		goto out;
+
+	if (is_ret_probe(tu)) {
+		entry->vaddr[0] = func;
+		entry->vaddr[1] = instruction_pointer(regs);
+		data = DATAOF_TRACE_ENTRY(entry, true);
+	} else {
+		entry->vaddr[0] = instruction_pointer(regs);
+		data = DATAOF_TRACE_ENTRY(entry, false);
+	}
+
+	memcpy(data, ucb->buf, tu->tp.size + dsize);
+
+	if (size - esize > tu->tp.size + dsize) {
+		int len = tu->tp.size + dsize;
+
+		memset(data + len, 0, size - esize - len);
+	}
+
+	perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
+ out:
+	preempt_enable();
+}
+
+/* uprobe profile handler */
+static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs,
+			    struct uprobe_cpu_buffer *ucb, int dsize)
+{
+	if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
+		return UPROBE_HANDLER_REMOVE;
+
+	if (!is_ret_probe(tu))
+		__uprobe_perf_func(tu, 0, regs, ucb, dsize);
+	return 0;
+}
+
+static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
+				struct pt_regs *regs,
+				struct uprobe_cpu_buffer *ucb, int dsize)
+{
+	__uprobe_perf_func(tu, func, regs, ucb, dsize);
+}
+#endif	/* CONFIG_PERF_EVENTS */
+
+static int
+trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type,
+		      void *data)
+{
+	struct trace_uprobe *tu = event->data;
+	struct ftrace_event_file *file = data;
+
+	switch (type) {
+	case TRACE_REG_REGISTER:
+		return probe_event_enable(tu, file, NULL);
+
+	case TRACE_REG_UNREGISTER:
+		probe_event_disable(tu, file);
+		return 0;
+
+#ifdef CONFIG_PERF_EVENTS
+	case TRACE_REG_PERF_REGISTER:
+		return probe_event_enable(tu, NULL, uprobe_perf_filter);
+
+	case TRACE_REG_PERF_UNREGISTER:
+		probe_event_disable(tu, NULL);
+		return 0;
+
+	case TRACE_REG_PERF_OPEN:
+		return uprobe_perf_open(tu, data);
+
+	case TRACE_REG_PERF_CLOSE:
+		return uprobe_perf_close(tu, data);
+
+#endif
+	default:
+		return 0;
+	}
+	return 0;
+}
+
+static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
+{
+	struct trace_uprobe *tu;
+	struct uprobe_dispatch_data udd;
+	struct uprobe_cpu_buffer *ucb;
+	int dsize, esize;
+	int ret = 0;
+
+
+	tu = container_of(con, struct trace_uprobe, consumer);
+	tu->nhit++;
+
+	udd.tu = tu;
+	udd.bp_addr = instruction_pointer(regs);
+
+	current->utask->vaddr = (unsigned long) &udd;
+
+	if (WARN_ON_ONCE(!uprobe_cpu_buffer))
+		return 0;
+
+	dsize = __get_data_size(&tu->tp, regs);
+	esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
+
+	ucb = uprobe_buffer_get();
+	store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
+
+	if (tu->tp.flags & TP_FLAG_TRACE)
+		ret |= uprobe_trace_func(tu, regs, ucb, dsize);
+
+#ifdef CONFIG_PERF_EVENTS
+	if (tu->tp.flags & TP_FLAG_PROFILE)
+		ret |= uprobe_perf_func(tu, regs, ucb, dsize);
+#endif
+	uprobe_buffer_put(ucb);
+	return ret;
+}
+
+static int uretprobe_dispatcher(struct uprobe_consumer *con,
+				unsigned long func, struct pt_regs *regs)
+{
+	struct trace_uprobe *tu;
+	struct uprobe_dispatch_data udd;
+	struct uprobe_cpu_buffer *ucb;
+	int dsize, esize;
+
+	tu = container_of(con, struct trace_uprobe, consumer);
+
+	udd.tu = tu;
+	udd.bp_addr = func;
+
+	current->utask->vaddr = (unsigned long) &udd;
+
+	if (WARN_ON_ONCE(!uprobe_cpu_buffer))
+		return 0;
+
+	dsize = __get_data_size(&tu->tp, regs);
+	esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
+
+	ucb = uprobe_buffer_get();
+	store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
+
+	if (tu->tp.flags & TP_FLAG_TRACE)
+		uretprobe_trace_func(tu, func, regs, ucb, dsize);
+
+#ifdef CONFIG_PERF_EVENTS
+	if (tu->tp.flags & TP_FLAG_PROFILE)
+		uretprobe_perf_func(tu, func, regs, ucb, dsize);
+#endif
+	uprobe_buffer_put(ucb);
+	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->tp.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->tp, is_ret_probe(tu)) < 0)
+		return -ENOMEM;
+
+	ret = register_ftrace_event(&call->event);
+	if (!ret) {
+		kfree(call->print_fmt);
+		return -ENODEV;
+	}
+
+	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",
+			ftrace_event_name(call));
+		kfree(call->print_fmt);
+		unregister_ftrace_event(&call->event);
+	}
+
+	return ret;
+}
+
+static int unregister_uprobe_event(struct trace_uprobe *tu)
+{
+	int ret;
+
+	/* tu->event is unregistered in trace_remove_event_call() */
+	ret = trace_remove_event_call(&tu->tp.call);
+	if (ret)
+		return ret;
+	kfree(tu->tp.call.print_fmt);
+	tu->tp.call.print_fmt = NULL;
+	return 0;
+}
+
+/* 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 (IS_ERR(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);