[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/file.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_fdget_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();
	if (file)
		fput(file);
	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>
c35f268c	13	#include <linux/file.h>
3aed4dca	14	#include <linux/list.h>
149b9a9d YB	15	#include <linux/module.h>
	16	#include <linux/namei.h>
	17	#include <linux/slab.h>
3aed4dca	18	#include <linux/uaccess.h>
853f5b15 MJ	19	#include <linux/uprobes.h>
853f5b15 MJ	20
2df37e95	21	#include <lttng/events.h>
a67ba386	22	#include <lttng/events-internal.h>
2df37e95	23	#include <lttng/tracer.h>
149b9a9d	24	#include <wrapper/irqflags.h>
24591303	25	#include <ringbuffer/frontend_types.h>
149b9a9d YB	26	#include <wrapper/vmalloc.h>
	27
	28	static
83b802dc	29	int lttng_uprobes_event_handler_pre(struct uprobe_consumer uc, struct pt_regs regs)
149b9a9d	30	{
3aed4dca FD	31	struct lttng_uprobe_handler *uprobe_handler =
3aed4dca FD	32	container_of(uc, struct lttng_uprobe_handler, up_consumer);
e2d5dbc7	33	struct lttng_kernel_event_common *event = uprobe_handler->event;
a92e844e	34	struct lttng_kernel_probe_ctx lttng_probe_ctx = {
e2d5dbc7	35	.event = event,
149b9a9d YB	36	.interruptible = !lttng_regs_irqs_disabled(regs),
149b9a9d YB	37	};
149b9a9d YB	38	struct {
149b9a9d YB	39	unsigned long ip;
56377c91	40	} payload;
149b9a9d	41
e2d5dbc7 MD	42	switch (event->type) {
	43	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	44	{
	45	struct lttng_kernel_event_recorder *event_recorder =
	46	container_of(event, struct lttng_kernel_event_recorder, parent);
f7d06400	47	struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
e2d5dbc7	48
f7d06400	49	if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active)))
e2d5dbc7	50	return 0;
f7d06400	51	if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled)))
e2d5dbc7 MD	52	return 0;
	53	break;
	54	}
	55	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
	56	break;
	57	default:
	58	WARN_ON_ONCE(1);
	59	}
9de67196	60
e2d5dbc7	61	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
9de67196 FD	62	return 0;
9de67196 FD	63
e2d5dbc7 MD	64	switch (event->type) {
	65	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	66	{
	67	struct lttng_kernel_event_recorder *event_recorder =
	68	container_of(event, struct lttng_kernel_event_recorder, parent);
f7d06400	69	struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
8a57ec02	70	struct lttng_kernel_ring_buffer_ctx ctx;
e2d5dbc7 MD	71	int ret;
e2d5dbc7 MD	72
b1199bd3 MD	73	lib_ring_buffer_ctx_init(&ctx, event_recorder,
b1199bd3 MD	74	sizeof(payload), lttng_alignof(payload), &lttng_probe_ctx);
e2d5dbc7	75
c2fb9c1c	76	ret = chan->ops->event_reserve(&ctx);
e2d5dbc7 MD	77	if (ret < 0)
	78	return 0;
	79
	80	/* Event payload. */
	81	payload.ip = (unsigned long)instruction_pointer(regs);
	82
f5ffbd77	83	chan->ops->event_write(&ctx, &payload, sizeof(payload), lttng_alignof(payload));
e2d5dbc7 MD	84	chan->ops->event_commit(&ctx);
	85	break;
	86	}
	87	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
	88	{
	89	struct lttng_kernel_event_notifier *event_notifier =
	90	container_of(event, struct lttng_kernel_event_notifier, parent);
	91	struct lttng_kernel_notification_ctx notif_ctx;
	92
	93	notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
	94	event_notifier->notification_send(event_notifier, NULL, NULL, &notif_ctx);
	95	break;
	96	}
	97	default:
	98	WARN_ON_ONCE(1);
	99	}
9de67196 FD	100	return 0;
	101	}
	102
6c8c025b MD	103	static const struct lttng_kernel_event_field *event_fields[] = {
	104	lttng_kernel_static_event_field("ip",
	105	lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16),
4697aac7	106	false, false),
6c8c025b MD	107	};
	108
	109	static const struct lttng_kernel_tracepoint_class tp_class = {
	110	.nr_fields = ARRAY_SIZE(event_fields),
	111	.fields = event_fields,
	112	};
437d5aa5	113
149b9a9d YB	114	/*
	115	* Create event description.
	116	*/
	117	static
17806c46	118	int lttng_create_uprobe_event(const char name, struct lttng_kernel_event_common event)
149b9a9d	119	{
437d5aa5	120	struct lttng_kernel_event_desc *desc;
149b9a9d YB	121	int ret;
149b9a9d YB	122
437d5aa5	123	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
149b9a9d YB	124	if (!desc)
149b9a9d YB	125	return -ENOMEM;
6c8c025b	126	desc->tp_class = &tp_class;
437d5aa5 MD	127	desc->event_name = kstrdup(name, GFP_KERNEL);
437d5aa5 MD	128	if (!desc->event_name) {
149b9a9d YB	129	ret = -ENOMEM;
	130	goto error_str;
	131	}
149b9a9d	132	desc->owner = THIS_MODULE;
17806c46	133	event->priv->desc = desc;
9de67196 FD	134
	135	return 0;
	136
	137	error_str:
	138	kfree(desc);
	139	return ret;
	140	}
	141
56377c91 FD	142	/*
	143	* Returns the inode struct from the current task and an fd. The inode is
	144	* grabbed by this function and must be put once we are done with it using
	145	* iput().
	146	*/
	147	static struct inode *get_inode_from_fd(int fd)
	148	{
	149	struct file *file;
	150	struct inode *inode;
	151
	152	rcu_read_lock();
	153	/*
	154	* Returns the file backing the given fd. Needs to be done inside an RCU
	155	* critical section.
	156	*/
c35f268c	157	file = lttng_lookup_fdget_rcu(fd);
56377c91	158	if (file == NULL) {
5a15f70c	159	printk(KERN_WARNING "LTTng: Cannot access file backing the fd(%d)\n", fd);
56377c91 FD	160	inode = NULL;
	161	goto error;
	162	}
	163
	164	/* Grab a reference on the inode. */
	165	inode = igrab(file->f_path.dentry->d_inode);
	166	if (inode == NULL)
5a15f70c	167	printk(KERN_WARNING "LTTng: Cannot grab a reference on the inode.\n");
c35f268c	168
56377c91 FD	169	error:
56377c91 FD	170	rcu_read_unlock();
c35f268c KS	171	if (file)
c35f268c KS	172	fput(file);
56377c91 FD	173	return inode;
	174	}
	175
83b802dc FD	176
	177	static
	178	int lttng_uprobes_add_callsite(struct lttng_uprobe *uprobe,
606828e4	179	struct lttng_kernel_abi_event_callsite __user *callsite,
83b802dc FD	180	int (handler)(struct uprobe_consumer self, struct pt_regs *regs),
83b802dc FD	181	void *priv_data)
149b9a9d	182	{
3aed4dca FD	183	int ret = 0;
	184	struct lttng_uprobe_handler *uprobe_handler;
	185
83b802dc	186	if (!priv_data) {
3aed4dca FD	187	ret = -EINVAL;
	188	goto end;
	189	}
	190
	191	uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
	192	if (!uprobe_handler) {
5a15f70c	193	printk(KERN_WARNING "LTTng: Error allocating uprobe_handler");
3aed4dca FD	194	ret = -ENOMEM;
	195	goto end;
	196	}
	197
196bfc6a	198	/* Ensure the memory we just allocated don't notify page faults. */
263b6c88	199	wrapper_vmalloc_sync_mappings();
3aed4dca	200
e2d5dbc7	201	uprobe_handler->event = priv_data;
83b802dc	202	uprobe_handler->up_consumer.handler = handler;
3aed4dca FD	203
	204	ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
	205	if (ret) {
	206	goto register_error;
	207	}
	208
853f5b15	209	ret = uprobe_register(uprobe->inode,
3aed4dca FD	210	uprobe_handler->offset, &uprobe_handler->up_consumer);
3aed4dca FD	211	if (ret) {
5a15f70c	212	printk(KERN_WARNING "LTTng: Error registering probe on inode %lu "
83b802dc	213	"and offset 0x%llx\n", uprobe->inode->i_ino,
3aed4dca FD	214	uprobe_handler->offset);
	215	ret = -1;
	216	goto register_error;
	217	}
	218
83b802dc	219	list_add(&uprobe_handler->node, &uprobe->head);
3aed4dca FD	220
	221	return ret;
	222
	223	register_error:
	224	kfree(uprobe_handler);
	225	end:
	226	return ret;
	227	}
3aed4dca	228
e2d5dbc7	229	int lttng_uprobes_event_add_callsite(struct lttng_kernel_event_common *event,
606828e4	230	struct lttng_kernel_abi_event_callsite __user *callsite)
83b802dc	231	{
e2d5dbc7 MD	232	return lttng_uprobes_add_callsite(&event->priv->u.uprobe, callsite,
e2d5dbc7 MD	233	lttng_uprobes_event_handler_pre, event);
83b802dc FD	234	}
	235	EXPORT_SYMBOL_GPL(lttng_uprobes_event_add_callsite);
	236
	237	static
	238	int lttng_uprobes_register(struct lttng_uprobe *uprobe, int fd)
3aed4dca FD	239	{
3aed4dca FD	240	int ret = 0;
56377c91	241	struct inode *inode;
149b9a9d	242
56377c91 FD	243	inode = get_inode_from_fd(fd);
56377c91 FD	244	if (!inode) {
5a15f70c	245	printk(KERN_WARNING "LTTng: Cannot get inode from fd\n");
56377c91 FD	246	ret = -EBADF;
	247	goto inode_error;
	248	}
83b802dc FD	249	uprobe->inode = inode;
	250	INIT_LIST_HEAD(&uprobe->head);
	251
	252	inode_error:
	253	return ret;
	254	}
	255
17806c46	256	int lttng_uprobes_register_event(const char name, int fd, struct lttng_kernel_event_common event)
83b802dc FD	257	{
	258	int ret = 0;
	259
17806c46	260	ret = lttng_create_uprobe_event(name, event);
83b802dc FD	261	if (ret)
	262	goto error;
	263
17806c46	264	ret = lttng_uprobes_register(&event->priv->u.uprobe, fd);
83b802dc FD	265	if (ret)
83b802dc FD	266	goto register_error;
149b9a9d	267
149b9a9d YB	268	return 0;
149b9a9d YB	269
83b802dc	270	register_error:
17806c46 MD	271	kfree(event->priv->desc->event_name);
17806c46 MD	272	kfree(event->priv->desc);
149b9a9d YB	273	error:
	274	return ret;
	275	}
83b802dc	276	EXPORT_SYMBOL_GPL(lttng_uprobes_register_event);
149b9a9d	277
9de67196 FD	278	static
9de67196 FD	279	void lttng_uprobes_unregister(struct inode inode, struct list_head head)
149b9a9d	280	{
3aed4dca FD	281	struct lttng_uprobe_handler iter, tmp;
	282
	283	/*
	284	* Iterate over the list of handler, remove each handler from the list
	285	* and free the struct.
	286	*/
9de67196	287	list_for_each_entry_safe(iter, tmp, head, node) {
853f5b15	288	uprobe_unregister(inode, iter->offset, &iter->up_consumer);
3aed4dca FD	289	list_del(&iter->node);
	290	kfree(iter);
	291	}
9de67196 FD	292	}
9de67196 FD	293
17806c46	294	void lttng_uprobes_unregister_event(struct lttng_kernel_event_common *event)
9de67196	295	{
17806c46	296	lttng_uprobes_unregister(event->priv->u.uprobe.inode, &event->priv->u.uprobe.head);
149b9a9d	297	}
83b802dc	298	EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event);
149b9a9d	299
17806c46	300	void lttng_uprobes_destroy_event_private(struct lttng_kernel_event_common *event)
149b9a9d	301	{
17806c46 MD	302	iput(event->priv->u.uprobe.inode);
	303	kfree(event->priv->desc->event_name);
	304	kfree(event->priv->desc);
149b9a9d	305	}
83b802dc	306	EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_private);
149b9a9d	307
a67ba386	308	void lttng_uprobes_destroy_event_notifier_private(struct lttng_kernel_event_notifier *event_notifier)
9de67196	309	{
a67ba386 MD	310	iput(event_notifier->priv->parent.u.uprobe.inode);
	311	kfree(event_notifier->priv->parent.desc->event_name);
	312	kfree(event_notifier->priv->parent.desc);
9de67196 FD	313	}
	314	EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_notifier_private);
	315
149b9a9d YB	316	MODULE_LICENSE("GPL and additional rights");
	317	MODULE_AUTHOR("Yannick Brosseau");
	318	MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");