Skip to content
Snippets Groups Projects
Select Git revision
  • 84d7ed799fd6c1366547d88ddb8188c65de3b94f
  • vme-testing default
  • ci-test
  • master
  • remoteproc
  • am625-sk-ov5640
  • pcal6534-upstreaming
  • lps22df-upstreaming
  • msc-upstreaming
  • imx8mp
  • iio/noa1305
  • vme-next
  • vme-next-4.14-rc4
  • v4.14-rc4
  • v4.14-rc3
  • v4.14-rc2
  • v4.14-rc1
  • v4.13
  • vme-next-4.13-rc7
  • v4.13-rc7
  • v4.13-rc6
  • v4.13-rc5
  • v4.13-rc4
  • v4.13-rc3
  • v4.13-rc2
  • v4.13-rc1
  • v4.12
  • v4.12-rc7
  • v4.12-rc6
  • v4.12-rc5
  • v4.12-rc4
  • v4.12-rc3
32 results

trace_uprobe.c

Blame
  • trace_uprobe.c 17.77 KiB
    /*
     * 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"
    
    /*
     * 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' 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;
    
    	inode = igrab(path.dentry->d_inode);
    	path_put(&path);
    
    	if (!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);
    	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 or file.\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 = instruction_pointer(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;
    	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 = instruction_pointer(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, NULL);
    
     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);