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