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

/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
 *
 * 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>
 *
 */

#include <wrapper/fdtable.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/uprobes.h>

#include <lttng/events.h>
#include <lttng/events-internal.h>
#include <lttng/tracer.h>
#include <wrapper/irqflags.h>
#include <ringbuffer/frontend_types.h>
#include <wrapper/vmalloc.h>

static
int lttng_uprobes_event_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_kernel_event_common *event = uprobe_handler->event;
	struct lttng_kernel_probe_ctx lttng_probe_ctx = {
		.event = event,
		.interruptible = !lttng_regs_irqs_disabled(regs),
	};
	struct {
		unsigned long ip;
	} payload;

	switch (event->type) {
	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	{
		struct lttng_kernel_event_recorder *event_recorder =
			container_of(event, struct lttng_kernel_event_recorder, parent);
		struct lttng_kernel_channel_buffer *chan = event_recorder->chan;

		if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active)))
			return 0;
		if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled)))
			return 0;
		break;
	}
	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
		break;
	default:
		WARN_ON_ONCE(1);
	}

	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
		return 0;

	switch (event->type) {
	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	{
		struct lttng_kernel_event_recorder *event_recorder =
			container_of(event, struct lttng_kernel_event_recorder, parent);
		struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
		struct lttng_kernel_ring_buffer_ctx ctx;
		int ret;

		lib_ring_buffer_ctx_init(&ctx, event_recorder,
			sizeof(payload), lttng_alignof(payload), &lttng_probe_ctx);

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

		/* Event payload. */
		payload.ip = (unsigned long)instruction_pointer(regs);

		chan->ops->event_write(&ctx, &payload, sizeof(payload), lttng_alignof(payload));
		chan->ops->event_commit(&ctx);
		break;
	}
	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
	{
		struct lttng_kernel_event_notifier *event_notifier =
			container_of(event, struct lttng_kernel_event_notifier, parent);
		struct lttng_kernel_notification_ctx notif_ctx;

		notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
		event_notifier->notification_send(event_notifier, NULL, NULL, &notif_ctx);
		break;
	}
	default:
		WARN_ON_ONCE(1);
	}
	return 0;
}

static const struct lttng_kernel_event_field *event_fields[] = {
	lttng_kernel_static_event_field("ip",
		lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16),
		false, false),
};

static const struct lttng_kernel_tracepoint_class tp_class = {
	.nr_fields = ARRAY_SIZE(event_fields),
	.fields = event_fields,
};

/*
 * Create event description.
 */
static
int lttng_create_uprobe_event(const char *name, struct lttng_kernel_event_common *event)
{
	struct lttng_kernel_event_desc *desc;
	int ret;

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

	return 0;

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 = lttng_lookup_fd_rcu(fd);
	if (file == NULL) {
		printk(KERN_WARNING "LTTng: 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 "LTTng: Cannot grab a reference on the inode.\n");
error:
	rcu_read_unlock();
	return inode;
}


static
int lttng_uprobes_add_callsite(struct lttng_uprobe *uprobe,
	struct lttng_kernel_abi_event_callsite __user *callsite,
	int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs),
	void *priv_data)
{
	int ret = 0;
	struct lttng_uprobe_handler *uprobe_handler;

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

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

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

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

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

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

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

	return ret;

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

int lttng_uprobes_event_add_callsite(struct lttng_kernel_event_common *event,
	struct lttng_kernel_abi_event_callsite __user *callsite)
{
	return lttng_uprobes_add_callsite(&event->priv->u.uprobe, callsite,
		lttng_uprobes_event_handler_pre, event);
}
EXPORT_SYMBOL_GPL(lttng_uprobes_event_add_callsite);

static
int lttng_uprobes_register(struct lttng_uprobe *uprobe, int fd)
{
	int ret = 0;
	struct inode *inode;

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

inode_error:
	return ret;
}

int lttng_uprobes_register_event(const char *name, int fd, struct lttng_kernel_event_common *event)
{
	int ret = 0;

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

	ret = lttng_uprobes_register(&event->priv->u.uprobe, fd);
	if (ret)
		goto register_error;

	return 0;

register_error:
	kfree(event->priv->desc->event_name);
	kfree(event->priv->desc);
error:
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_uprobes_register_event);

static
void lttng_uprobes_unregister(struct inode *inode, struct list_head *head)
{
	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, head, node) {
		uprobe_unregister(inode, iter->offset, &iter->up_consumer);
		list_del(&iter->node);
		kfree(iter);
	}
}

void lttng_uprobes_unregister_event(struct lttng_kernel_event_common *event)
{
	lttng_uprobes_unregister(event->priv->u.uprobe.inode, &event->priv->u.uprobe.head);
}
EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event);

void lttng_uprobes_destroy_event_private(struct lttng_kernel_event_common *event)
{
	iput(event->priv->u.uprobe.inode);
	kfree(event->priv->desc->event_name);
	kfree(event->priv->desc);
}
EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_private);

void lttng_uprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier)
{
	iput(event_notifier->priv->parent.u.uprobe.inode);
	kfree(event_notifier->priv->parent.desc->event_name);
	kfree(event_notifier->priv->parent.desc);
}
EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_notifier_private);

MODULE_LICENSE("GPL and additional rights");
MODULE_AUTHOR("Yannick Brosseau");
MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");
Commit	Line	Data
b7cdc182	1	/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
8134eb60	2	*
149b9a9d YB	3	* probes/lttng-uprobes.c
	4	*
	5	* LTTng uprobes integration module.
	6	*
	7	* Copyright (C) 2013 Yannick Brosseau <yannick.brosseau@gmail.com>
	8	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	9	*
149b9a9d YB	10	*/
149b9a9d YB	11
0aebcd68	12	#include <wrapper/fdtable.h>
3aed4dca	13	#include <linux/list.h>
149b9a9d YB	14	#include <linux/module.h>
	15	#include <linux/namei.h>
	16	#include <linux/slab.h>
3aed4dca	17	#include <linux/uaccess.h>
853f5b15 MJ	18	#include <linux/uprobes.h>
853f5b15 MJ	19
2df37e95	20	#include <lttng/events.h>
a67ba386	21	#include <lttng/events-internal.h>
2df37e95	22	#include <lttng/tracer.h>
149b9a9d	23	#include <wrapper/irqflags.h>
24591303	24	#include <ringbuffer/frontend_types.h>
149b9a9d YB	25	#include <wrapper/vmalloc.h>
	26
	27	static
83b802dc	28	int lttng_uprobes_event_handler_pre(struct uprobe_consumer uc, struct pt_regs regs)
149b9a9d	29	{
3aed4dca FD	30	struct lttng_uprobe_handler *uprobe_handler =
3aed4dca FD	31	container_of(uc, struct lttng_uprobe_handler, up_consumer);
e2d5dbc7	32	struct lttng_kernel_event_common *event = uprobe_handler->event;
a92e844e	33	struct lttng_kernel_probe_ctx lttng_probe_ctx = {
e2d5dbc7	34	.event = event,
149b9a9d YB	35	.interruptible = !lttng_regs_irqs_disabled(regs),
149b9a9d YB	36	};
149b9a9d YB	37	struct {
149b9a9d YB	38	unsigned long ip;
56377c91	39	} payload;
149b9a9d	40
e2d5dbc7 MD	41	switch (event->type) {
	42	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	43	{
	44	struct lttng_kernel_event_recorder *event_recorder =
	45	container_of(event, struct lttng_kernel_event_recorder, parent);
f7d06400	46	struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
e2d5dbc7	47
f7d06400	48	if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active)))
e2d5dbc7	49	return 0;
f7d06400	50	if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled)))
e2d5dbc7 MD	51	return 0;
	52	break;
	53	}
	54	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
	55	break;
	56	default:
	57	WARN_ON_ONCE(1);
	58	}
9de67196	59
e2d5dbc7	60	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
9de67196 FD	61	return 0;
9de67196 FD	62
e2d5dbc7 MD	63	switch (event->type) {
	64	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	65	{
	66	struct lttng_kernel_event_recorder *event_recorder =
	67	container_of(event, struct lttng_kernel_event_recorder, parent);
f7d06400	68	struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
8a57ec02	69	struct lttng_kernel_ring_buffer_ctx ctx;
e2d5dbc7 MD	70	int ret;
e2d5dbc7 MD	71
b1199bd3 MD	72	lib_ring_buffer_ctx_init(&ctx, event_recorder,
b1199bd3 MD	73	sizeof(payload), lttng_alignof(payload), &lttng_probe_ctx);
e2d5dbc7	74
c2fb9c1c	75	ret = chan->ops->event_reserve(&ctx);
e2d5dbc7 MD	76	if (ret < 0)
	77	return 0;
	78
	79	/* Event payload. */
	80	payload.ip = (unsigned long)instruction_pointer(regs);
	81
f5ffbd77	82	chan->ops->event_write(&ctx, &payload, sizeof(payload), lttng_alignof(payload));
e2d5dbc7 MD	83	chan->ops->event_commit(&ctx);
	84	break;
	85	}
	86	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
	87	{
	88	struct lttng_kernel_event_notifier *event_notifier =
	89	container_of(event, struct lttng_kernel_event_notifier, parent);
	90	struct lttng_kernel_notification_ctx notif_ctx;
	91
	92	notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
	93	event_notifier->notification_send(event_notifier, NULL, NULL, &notif_ctx);
	94	break;
	95	}
	96	default:
	97	WARN_ON_ONCE(1);
	98	}
9de67196 FD	99	return 0;
	100	}
	101
6c8c025b MD	102	static const struct lttng_kernel_event_field *event_fields[] = {
	103	lttng_kernel_static_event_field("ip",
	104	lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16),
4697aac7	105	false, false),
6c8c025b MD	106	};
	107
	108	static const struct lttng_kernel_tracepoint_class tp_class = {
	109	.nr_fields = ARRAY_SIZE(event_fields),
	110	.fields = event_fields,
	111	};
437d5aa5	112
149b9a9d YB	113	/*
	114	* Create event description.
	115	*/
	116	static
17806c46	117	int lttng_create_uprobe_event(const char name, struct lttng_kernel_event_common event)
149b9a9d	118	{
437d5aa5	119	struct lttng_kernel_event_desc *desc;
149b9a9d YB	120	int ret;
149b9a9d YB	121
437d5aa5	122	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
149b9a9d YB	123	if (!desc)
149b9a9d YB	124	return -ENOMEM;
6c8c025b	125	desc->tp_class = &tp_class;
437d5aa5 MD	126	desc->event_name = kstrdup(name, GFP_KERNEL);
437d5aa5 MD	127	if (!desc->event_name) {
149b9a9d YB	128	ret = -ENOMEM;
	129	goto error_str;
	130	}
149b9a9d	131	desc->owner = THIS_MODULE;
17806c46	132	event->priv->desc = desc;
9de67196 FD	133
	134	return 0;
	135
	136	error_str:
	137	kfree(desc);
	138	return ret;
	139	}
	140
56377c91 FD	141	/*
	142	* Returns the inode struct from the current task and an fd. The inode is
	143	* grabbed by this function and must be put once we are done with it using
	144	* iput().
	145	*/
	146	static struct inode *get_inode_from_fd(int fd)
	147	{
	148	struct file *file;
	149	struct inode *inode;
	150
	151	rcu_read_lock();
	152	/*
	153	* Returns the file backing the given fd. Needs to be done inside an RCU
	154	* critical section.
	155	*/
0aebcd68	156	file = lttng_lookup_fd_rcu(fd);
56377c91	157	if (file == NULL) {
5a15f70c	158	printk(KERN_WARNING "LTTng: Cannot access file backing the fd(%d)\n", fd);
56377c91 FD	159	inode = NULL;
	160	goto error;
	161	}
	162
	163	/* Grab a reference on the inode. */
	164	inode = igrab(file->f_path.dentry->d_inode);
	165	if (inode == NULL)
5a15f70c	166	printk(KERN_WARNING "LTTng: Cannot grab a reference on the inode.\n");
56377c91 FD	167	error:
	168	rcu_read_unlock();
	169	return inode;
	170	}
	171
83b802dc FD	172
	173	static
	174	int lttng_uprobes_add_callsite(struct lttng_uprobe *uprobe,
606828e4	175	struct lttng_kernel_abi_event_callsite __user *callsite,
83b802dc FD	176	int (handler)(struct uprobe_consumer self, struct pt_regs *regs),
83b802dc FD	177	void *priv_data)
149b9a9d	178	{
3aed4dca FD	179	int ret = 0;
	180	struct lttng_uprobe_handler *uprobe_handler;
	181
83b802dc	182	if (!priv_data) {
3aed4dca FD	183	ret = -EINVAL;
	184	goto end;
	185	}
	186
	187	uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
	188	if (!uprobe_handler) {
5a15f70c	189	printk(KERN_WARNING "LTTng: Error allocating uprobe_handler");
3aed4dca FD	190	ret = -ENOMEM;
	191	goto end;
	192	}
	193
196bfc6a	194	/* Ensure the memory we just allocated don't notify page faults. */
263b6c88	195	wrapper_vmalloc_sync_mappings();
3aed4dca	196
e2d5dbc7	197	uprobe_handler->event = priv_data;
83b802dc	198	uprobe_handler->up_consumer.handler = handler;
3aed4dca FD	199
	200	ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
	201	if (ret) {
	202	goto register_error;
	203	}
	204
853f5b15	205	ret = uprobe_register(uprobe->inode,
3aed4dca FD	206	uprobe_handler->offset, &uprobe_handler->up_consumer);
3aed4dca FD	207	if (ret) {
5a15f70c	208	printk(KERN_WARNING "LTTng: Error registering probe on inode %lu "
83b802dc	209	"and offset 0x%llx\n", uprobe->inode->i_ino,
3aed4dca FD	210	uprobe_handler->offset);
	211	ret = -1;
	212	goto register_error;
	213	}
	214
83b802dc	215	list_add(&uprobe_handler->node, &uprobe->head);
3aed4dca FD	216
	217	return ret;
	218
	219	register_error:
	220	kfree(uprobe_handler);
	221	end:
	222	return ret;
	223	}
3aed4dca	224
e2d5dbc7	225	int lttng_uprobes_event_add_callsite(struct lttng_kernel_event_common *event,
606828e4	226	struct lttng_kernel_abi_event_callsite __user *callsite)
83b802dc	227	{
e2d5dbc7 MD	228	return lttng_uprobes_add_callsite(&event->priv->u.uprobe, callsite,
e2d5dbc7 MD	229	lttng_uprobes_event_handler_pre, event);
83b802dc FD	230	}
	231	EXPORT_SYMBOL_GPL(lttng_uprobes_event_add_callsite);
	232
	233	static
	234	int lttng_uprobes_register(struct lttng_uprobe *uprobe, int fd)
3aed4dca FD	235	{
3aed4dca FD	236	int ret = 0;
56377c91	237	struct inode *inode;
149b9a9d	238
56377c91 FD	239	inode = get_inode_from_fd(fd);
56377c91 FD	240	if (!inode) {
5a15f70c	241	printk(KERN_WARNING "LTTng: Cannot get inode from fd\n");
56377c91 FD	242	ret = -EBADF;
	243	goto inode_error;
	244	}
83b802dc FD	245	uprobe->inode = inode;
	246	INIT_LIST_HEAD(&uprobe->head);
	247
	248	inode_error:
	249	return ret;
	250	}
	251
17806c46	252	int lttng_uprobes_register_event(const char name, int fd, struct lttng_kernel_event_common event)
83b802dc FD	253	{
	254	int ret = 0;
	255
17806c46	256	ret = lttng_create_uprobe_event(name, event);
83b802dc FD	257	if (ret)
	258	goto error;
	259
17806c46	260	ret = lttng_uprobes_register(&event->priv->u.uprobe, fd);
83b802dc FD	261	if (ret)
83b802dc FD	262	goto register_error;
149b9a9d	263
149b9a9d YB	264	return 0;
149b9a9d YB	265
83b802dc	266	register_error:
17806c46 MD	267	kfree(event->priv->desc->event_name);
17806c46 MD	268	kfree(event->priv->desc);
149b9a9d YB	269	error:
	270	return ret;
	271	}
83b802dc	272	EXPORT_SYMBOL_GPL(lttng_uprobes_register_event);
149b9a9d	273
9de67196 FD	274	static
9de67196 FD	275	void lttng_uprobes_unregister(struct inode inode, struct list_head head)
149b9a9d	276	{
3aed4dca FD	277	struct lttng_uprobe_handler iter, tmp;
	278
	279	/*
	280	* Iterate over the list of handler, remove each handler from the list
	281	* and free the struct.
	282	*/
9de67196	283	list_for_each_entry_safe(iter, tmp, head, node) {
853f5b15	284	uprobe_unregister(inode, iter->offset, &iter->up_consumer);
3aed4dca FD	285	list_del(&iter->node);
	286	kfree(iter);
	287	}
9de67196 FD	288	}
9de67196 FD	289
17806c46	290	void lttng_uprobes_unregister_event(struct lttng_kernel_event_common *event)
9de67196	291	{
17806c46	292	lttng_uprobes_unregister(event->priv->u.uprobe.inode, &event->priv->u.uprobe.head);
149b9a9d	293	}
83b802dc	294	EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event);
149b9a9d	295
17806c46	296	void lttng_uprobes_destroy_event_private(struct lttng_kernel_event_common *event)
149b9a9d	297	{
17806c46 MD	298	iput(event->priv->u.uprobe.inode);
	299	kfree(event->priv->desc->event_name);
	300	kfree(event->priv->desc);
149b9a9d	301	}
83b802dc	302	EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_private);
149b9a9d	303
a67ba386	304	void lttng_uprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier)
9de67196	305	{
a67ba386 MD	306	iput(event_notifier->priv->parent.u.uprobe.inode);
	307	kfree(event_notifier->priv->parent.desc->event_name);
	308	kfree(event_notifier->priv->parent.desc);
9de67196 FD	309	}
	310	EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_notifier_private);
	311
149b9a9d YB	312	MODULE_LICENSE("GPL and additional rights");
	313	MODULE_AUTHOR("Yannick Brosseau");
	314	MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");