[lttng-modules.git] / probes / lttng-uprobes.c

/*
 * probes/lttng-uprobes.c
 *
 * LTTng uprobes integration module.
 *
 * Copyright (C) 2013 Yannick Brosseau <yannick.brosseau@gmail.com>
 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <linux/fdtable.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <lttng-events.h>
#include <lttng-tracer.h>
#include <wrapper/irqflags.h>
#include <wrapper/ringbuffer/frontend_types.h>
#include <wrapper/uprobes.h>
#include <wrapper/vmalloc.h>

static
int lttng_uprobes_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs)
{
	struct lttng_uprobe_handler *uprobe_handler =
		container_of(uc, struct lttng_uprobe_handler, up_consumer);
	struct lttng_event *event = uprobe_handler->event;
	struct lttng_probe_ctx lttng_probe_ctx = {
		.event = event,
		.interruptible = !lttng_regs_irqs_disabled(regs),
	};
	struct lttng_channel *chan = event->chan;
	struct lib_ring_buffer_ctx ctx;
	int ret;

	struct {
		unsigned long ip;
	} payload;

	if (unlikely(!ACCESS_ONCE(chan->session->active)))
		return 0;
	if (unlikely(!ACCESS_ONCE(chan->enabled)))
		return 0;
	if (unlikely(!ACCESS_ONCE(event->enabled)))
		return 0;

	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx,
		sizeof(payload), lttng_alignof(payload), -1);

	ret = chan->ops->event_reserve(&ctx, event->id);
	if (ret < 0)
		return 0;

	/* Event payload. */
	payload.ip = regs->ip;

	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	chan->ops->event_commit(&ctx);
	return 0;
}

/*
 * Create event description.
 */
static
int lttng_create_uprobe_event(const char *name, struct lttng_event *event)
{
	struct lttng_event_desc *desc;
	struct lttng_event_field *fields;
	int ret;

	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	if (!desc)
		return -ENOMEM;
	desc->name = kstrdup(name, GFP_KERNEL);
	if (!desc->name) {
		ret = -ENOMEM;
		goto error_str;
	}

	desc->nr_fields = 1;
	desc->fields = fields =
		kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);

	if (!desc->fields) {
		ret = -ENOMEM;
		goto error_fields;
	}
	fields[0].name = "ip";
	fields[0].type.atype = atype_integer;
	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	fields[0].type.u.basic.integer.reverse_byte_order = 0;
	fields[0].type.u.basic.integer.base = 16;
	fields[0].type.u.basic.integer.encoding = lttng_encode_none;

	desc->owner = THIS_MODULE;
	event->desc = desc;

	return 0;

error_fields:
	kfree(desc->name);
error_str:
	kfree(desc);
	return ret;
}

/*
 * Returns the inode struct from the current task and an fd. The inode is
 * grabbed by this function and must be put once we are done with it using
 * iput().
 */
static struct inode *get_inode_from_fd(int fd)
{
	struct file *file;
	struct inode *inode;

	rcu_read_lock();
	/*
	 * Returns the file backing the given fd. Needs to be done inside an RCU
	 * critical section.
	 */
	file = fcheck(fd);
	if (file == NULL) {
		printk(KERN_WARNING "Cannot access file backing the fd(%d)\n", fd);
		inode = NULL;
		goto error;
	}

	/* Grab a reference on the inode. */
	inode = igrab(file->f_path.dentry->d_inode);
	if (inode == NULL)
		printk(KERN_WARNING "Cannot grab a reference on the inode.\n");
error:
	rcu_read_unlock();
	return inode;
}

int lttng_uprobes_add_callsite(struct lttng_event *event,
	struct lttng_kernel_event_callsite __user *callsite)
{
	int ret = 0;
	struct lttng_uprobe_handler *uprobe_handler;

	if (!event) {
		ret = -EINVAL;
		goto end;
	}

	uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
	if (!uprobe_handler) {
		printk(KERN_WARNING "Error allocating uprobe_uprobe_handlers");
		ret = -ENOMEM;
		goto end;
	}

	/* Ensure the memory we just allocated don't trigger page faults. */
	wrapper_vmalloc_sync_all();

	uprobe_handler->event = event;
	uprobe_handler->up_consumer.handler = lttng_uprobes_handler_pre;

	ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
	if (ret) {
		goto register_error;
	}

	ret = wrapper_uprobe_register(event->u.uprobe.inode,
		      uprobe_handler->offset, &uprobe_handler->up_consumer);
	if (ret) {
		printk(KERN_WARNING "Error registering probe on inode %lu "
		       "and offset 0x%llx\n", event->u.uprobe.inode->i_ino,
		       uprobe_handler->offset);
		ret = -1;
		goto register_error;
	}

	list_add(&uprobe_handler->node, &event->u.uprobe.head);

	return ret;

register_error:
	kfree(uprobe_handler);
end:
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_uprobes_add_callsite);

int lttng_uprobes_register(const char *name, int fd, struct lttng_event *event)
{
	int ret = 0;
	struct inode *inode;

	ret = lttng_create_uprobe_event(name, event);
	if (ret)
		goto error;

	inode = get_inode_from_fd(fd);
	if (!inode) {
		printk(KERN_WARNING "Cannot get inode from fd\n");
		ret = -EBADF;
		goto inode_error;
	}
	event->u.uprobe.inode = inode;
	INIT_LIST_HEAD(&event->u.uprobe.head);

	return 0;

inode_error:
	kfree(event->desc->name);
	kfree(event->desc);
error:
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_uprobes_register);

void lttng_uprobes_unregister(struct lttng_event *event)
{
	struct lttng_uprobe_handler *iter, *tmp;

	/*
	 * Iterate over the list of handler, remove each handler from the list
	 * and free the struct.
	 */
	list_for_each_entry_safe(iter, tmp, &event->u.uprobe.head, node) {
		wrapper_uprobe_unregister(event->u.uprobe.inode, iter->offset,
			&iter->up_consumer);
		list_del(&iter->node);
		kfree(iter);
	}
}
EXPORT_SYMBOL_GPL(lttng_uprobes_unregister);

void lttng_uprobes_destroy_private(struct lttng_event *event)
{
	iput(event->u.uprobe.inode);
	kfree(event->desc->name);
	kfree(event->desc);
}
EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_private);

MODULE_LICENSE("GPL and additional rights");
MODULE_AUTHOR("Yannick Brosseau");
MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");
Commit	Line	Data
149b9a9d YB	1	/*
	2	* probes/lttng-uprobes.c
	3	*
	4	* LTTng uprobes integration module.
	5	*
	6	* Copyright (C) 2013 Yannick Brosseau <yannick.brosseau@gmail.com>
	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*
	9	* This library is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU Lesser General Public
	11	* License as published by the Free Software Foundation; only
	12	* version 2.1 of the License.
	13	*
	14	* This library is distributed in the hope that it will be useful,
	15	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* Lesser General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU Lesser General Public
	20	* License along with this library; if not, write to the Free Software
	21	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	22	*/
	23
	24	#include <linux/fdtable.h>
3aed4dca	25	#include <linux/list.h>
149b9a9d YB	26	#include <linux/module.h>
	27	#include <linux/namei.h>
	28	#include <linux/slab.h>
3aed4dca	29	#include <linux/uaccess.h>
149b9a9d YB	30	#include <lttng-events.h>
	31	#include <lttng-tracer.h>
	32	#include <wrapper/irqflags.h>
	33	#include <wrapper/ringbuffer/frontend_types.h>
	34	#include <wrapper/uprobes.h>
	35	#include <wrapper/vmalloc.h>
	36
	37	static
	38	int lttng_uprobes_handler_pre(struct uprobe_consumer uc, struct pt_regs regs)
	39	{
3aed4dca FD	40	struct lttng_uprobe_handler *uprobe_handler =
	41	container_of(uc, struct lttng_uprobe_handler, up_consumer);
	42	struct lttng_event *event = uprobe_handler->event;
149b9a9d YB	43	struct lttng_probe_ctx lttng_probe_ctx = {
	44	.event = event,
	45	.interruptible = !lttng_regs_irqs_disabled(regs),
	46	};
	47	struct lttng_channel *chan = event->chan;
	48	struct lib_ring_buffer_ctx ctx;
	49	int ret;
	50
	51	struct {
	52	unsigned long ip;
56377c91	53	} payload;
149b9a9d YB	54
	55	if (unlikely(!ACCESS_ONCE(chan->session->active)))
	56	return 0;
	57	if (unlikely(!ACCESS_ONCE(chan->enabled)))
	58	return 0;
	59	if (unlikely(!ACCESS_ONCE(event->enabled)))
	60	return 0;
	61
	62	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx,
	63	sizeof(payload), lttng_alignof(payload), -1);
	64
	65	ret = chan->ops->event_reserve(&ctx, event->id);
	66	if (ret < 0)
	67	return 0;
	68
	69	/* Event payload. */
	70	payload.ip = regs->ip;
56377c91	71
149b9a9d YB	72	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	73	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	74	chan->ops->event_commit(&ctx);
	75	return 0;
	76	}
	77
	78	/*
	79	* Create event description.
	80	*/
	81	static
	82	int lttng_create_uprobe_event(const char name, struct lttng_event event)
	83	{
	84	struct lttng_event_desc *desc;
	85	struct lttng_event_field *fields;
	86	int ret;
	87
	88	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	89	if (!desc)
	90	return -ENOMEM;
	91	desc->name = kstrdup(name, GFP_KERNEL);
	92	if (!desc->name) {
	93	ret = -ENOMEM;
	94	goto error_str;
	95	}
	96
	97	desc->nr_fields = 1;
	98	desc->fields = fields =
	99	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
	100
	101	if (!desc->fields) {
	102	ret = -ENOMEM;
	103	goto error_fields;
	104	}
	105	fields[0].name = "ip";
	106	fields[0].type.atype = atype_integer;
	107	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	108	fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	109	fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	110	fields[0].type.u.basic.integer.reverse_byte_order = 0;
	111	fields[0].type.u.basic.integer.base = 16;
	112	fields[0].type.u.basic.integer.encoding = lttng_encode_none;
	113
	114	desc->owner = THIS_MODULE;
	115	event->desc = desc;
	116
	117	return 0;
	118
	119	error_fields:
	120	kfree(desc->name);
	121	error_str:
	122	kfree(desc);
	123	return ret;
	124	}
	125
56377c91 FD	126	/*
	127	* Returns the inode struct from the current task and an fd. The inode is
	128	* grabbed by this function and must be put once we are done with it using
	129	* iput().
	130	*/
	131	static struct inode *get_inode_from_fd(int fd)
	132	{
	133	struct file *file;
	134	struct inode *inode;
	135
	136	rcu_read_lock();
	137	/*
	138	* Returns the file backing the given fd. Needs to be done inside an RCU
	139	* critical section.
	140	*/
	141	file = fcheck(fd);
	142	if (file == NULL) {
	143	printk(KERN_WARNING "Cannot access file backing the fd(%d)\n", fd);
	144	inode = NULL;
	145	goto error;
	146	}
	147
	148	/* Grab a reference on the inode. */
	149	inode = igrab(file->f_path.dentry->d_inode);
	150	if (inode == NULL)
	151	printk(KERN_WARNING "Cannot grab a reference on the inode.\n");
	152	error:
	153	rcu_read_unlock();
	154	return inode;
	155	}
	156
3aed4dca FD	157	int lttng_uprobes_add_callsite(struct lttng_event *event,
3aed4dca FD	158	struct lttng_kernel_event_callsite __user *callsite)
149b9a9d	159	{
3aed4dca FD	160	int ret = 0;
	161	struct lttng_uprobe_handler *uprobe_handler;
	162
	163	if (!event) {
	164	ret = -EINVAL;
	165	goto end;
	166	}
	167
	168	uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
	169	if (!uprobe_handler) {
	170	printk(KERN_WARNING "Error allocating uprobe_uprobe_handlers");
	171	ret = -ENOMEM;
	172	goto end;
	173	}
	174
	175	/* Ensure the memory we just allocated don't trigger page faults. */
	176	wrapper_vmalloc_sync_all();
	177
	178	uprobe_handler->event = event;
	179	uprobe_handler->up_consumer.handler = lttng_uprobes_handler_pre;
	180
	181	ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
	182	if (ret) {
	183	goto register_error;
	184	}
	185
	186	ret = wrapper_uprobe_register(event->u.uprobe.inode,
	187	uprobe_handler->offset, &uprobe_handler->up_consumer);
	188	if (ret) {
	189	printk(KERN_WARNING "Error registering probe on inode %lu "
	190	"and offset 0x%llx\n", event->u.uprobe.inode->i_ino,
	191	uprobe_handler->offset);
	192	ret = -1;
	193	goto register_error;
	194	}
	195
	196	list_add(&uprobe_handler->node, &event->u.uprobe.head);
	197
	198	return ret;
	199
	200	register_error:
	201	kfree(uprobe_handler);
	202	end:
	203	return ret;
	204	}
	205	EXPORT_SYMBOL_GPL(lttng_uprobes_add_callsite);
	206
	207	int lttng_uprobes_register(const char name, int fd, struct lttng_event event)
	208	{
	209	int ret = 0;
56377c91	210	struct inode *inode;
149b9a9d YB	211
	212	ret = lttng_create_uprobe_event(name, event);
	213	if (ret)
	214	goto error;
	215
56377c91 FD	216	inode = get_inode_from_fd(fd);
	217	if (!inode) {
	218	printk(KERN_WARNING "Cannot get inode from fd\n");
	219	ret = -EBADF;
	220	goto inode_error;
	221	}
56377c91	222	event->u.uprobe.inode = inode;
3aed4dca	223	INIT_LIST_HEAD(&event->u.uprobe.head);
149b9a9d	224
149b9a9d YB	225	return 0;
149b9a9d YB	226
56377c91	227	inode_error:
149b9a9d YB	228	kfree(event->desc->name);
	229	kfree(event->desc);
	230	error:
	231	return ret;
	232	}
	233	EXPORT_SYMBOL_GPL(lttng_uprobes_register);
	234
	235	void lttng_uprobes_unregister(struct lttng_event *event)
	236	{
3aed4dca FD	237	struct lttng_uprobe_handler iter, tmp;
	238
	239	/*
	240	* Iterate over the list of handler, remove each handler from the list
	241	* and free the struct.
	242	*/
	243	list_for_each_entry_safe(iter, tmp, &event->u.uprobe.head, node) {
	244	wrapper_uprobe_unregister(event->u.uprobe.inode, iter->offset,
	245	&iter->up_consumer);
	246	list_del(&iter->node);
	247	kfree(iter);
	248	}
149b9a9d YB	249	}
	250	EXPORT_SYMBOL_GPL(lttng_uprobes_unregister);
	251
	252	void lttng_uprobes_destroy_private(struct lttng_event *event)
	253	{
	254	iput(event->u.uprobe.inode);
	255	kfree(event->desc->name);
	256	kfree(event->desc);
	257	}
	258	EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_private);
	259
	260	MODULE_LICENSE("GPL and additional rights");
	261	MODULE_AUTHOR("Yannick Brosseau");
	262	MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");