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

/* SPDX-License-Identifier: (GPL-2.0 OR LGPL-2.1)
 *
 * 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 <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(!READ_ONCE(chan->session->active)))
		return 0;
	if (unlikely(!READ_ONCE(chan->enabled)))
		return 0;
	if (unlikely(!READ_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 = (unsigned long)instruction_pointer(regs);

	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_mappings();

	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
99fc3bbd MJ	1	/* SPDX-License-Identifier: (GPL-2.0 OR LGPL-2.1)
99fc3bbd MJ	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	*/
	11
	12	#include <linux/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>
149b9a9d YB	18	#include <lttng-events.h>
	19	#include <lttng-tracer.h>
	20	#include <wrapper/irqflags.h>
	21	#include <wrapper/ringbuffer/frontend_types.h>
	22	#include <wrapper/uprobes.h>
	23	#include <wrapper/vmalloc.h>
	24
	25	static
	26	int lttng_uprobes_handler_pre(struct uprobe_consumer uc, struct pt_regs regs)
	27	{
3aed4dca FD	28	struct lttng_uprobe_handler *uprobe_handler =
	29	container_of(uc, struct lttng_uprobe_handler, up_consumer);
	30	struct lttng_event *event = uprobe_handler->event;
149b9a9d YB	31	struct lttng_probe_ctx lttng_probe_ctx = {
	32	.event = event,
	33	.interruptible = !lttng_regs_irqs_disabled(regs),
	34	};
	35	struct lttng_channel *chan = event->chan;
	36	struct lib_ring_buffer_ctx ctx;
	37	int ret;
	38
	39	struct {
	40	unsigned long ip;
56377c91	41	} payload;
149b9a9d	42
b29a9c89	43	if (unlikely(!READ_ONCE(chan->session->active)))
149b9a9d	44	return 0;
b29a9c89	45	if (unlikely(!READ_ONCE(chan->enabled)))
149b9a9d	46	return 0;
b29a9c89	47	if (unlikely(!READ_ONCE(event->enabled)))
149b9a9d YB	48	return 0;
	49
	50	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx,
	51	sizeof(payload), lttng_alignof(payload), -1);
	52
	53	ret = chan->ops->event_reserve(&ctx, event->id);
	54	if (ret < 0)
	55	return 0;
	56
	57	/* Event payload. */
7445d54f	58	payload.ip = (unsigned long)instruction_pointer(regs);
56377c91	59
149b9a9d YB	60	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	61	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	62	chan->ops->event_commit(&ctx);
	63	return 0;
	64	}
	65
	66	/*
	67	* Create event description.
	68	*/
	69	static
	70	int lttng_create_uprobe_event(const char name, struct lttng_event event)
	71	{
	72	struct lttng_event_desc *desc;
	73	struct lttng_event_field *fields;
	74	int ret;
	75
	76	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	77	if (!desc)
	78	return -ENOMEM;
	79	desc->name = kstrdup(name, GFP_KERNEL);
	80	if (!desc->name) {
	81	ret = -ENOMEM;
	82	goto error_str;
	83	}
	84
	85	desc->nr_fields = 1;
	86	desc->fields = fields =
	87	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
	88
	89	if (!desc->fields) {
	90	ret = -ENOMEM;
	91	goto error_fields;
	92	}
	93	fields[0].name = "ip";
	94	fields[0].type.atype = atype_integer;
	95	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	96	fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	97	fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	98	fields[0].type.u.basic.integer.reverse_byte_order = 0;
	99	fields[0].type.u.basic.integer.base = 16;
	100	fields[0].type.u.basic.integer.encoding = lttng_encode_none;
	101
	102	desc->owner = THIS_MODULE;
	103	event->desc = desc;
	104
	105	return 0;
	106
	107	error_fields:
	108	kfree(desc->name);
	109	error_str:
	110	kfree(desc);
	111	return ret;
	112	}
	113
56377c91 FD	114	/*
	115	* Returns the inode struct from the current task and an fd. The inode is
	116	* grabbed by this function and must be put once we are done with it using
	117	* iput().
	118	*/
	119	static struct inode *get_inode_from_fd(int fd)
	120	{
	121	struct file *file;
	122	struct inode *inode;
	123
	124	rcu_read_lock();
	125	/*
	126	* Returns the file backing the given fd. Needs to be done inside an RCU
	127	* critical section.
	128	*/
	129	file = fcheck(fd);
	130	if (file == NULL) {
	131	printk(KERN_WARNING "Cannot access file backing the fd(%d)\n", fd);
	132	inode = NULL;
	133	goto error;
	134	}
	135
	136	/* Grab a reference on the inode. */
	137	inode = igrab(file->f_path.dentry->d_inode);
	138	if (inode == NULL)
	139	printk(KERN_WARNING "Cannot grab a reference on the inode.\n");
	140	error:
	141	rcu_read_unlock();
	142	return inode;
	143	}
	144
3aed4dca FD	145	int lttng_uprobes_add_callsite(struct lttng_event *event,
3aed4dca FD	146	struct lttng_kernel_event_callsite __user *callsite)
149b9a9d	147	{
3aed4dca FD	148	int ret = 0;
	149	struct lttng_uprobe_handler *uprobe_handler;
	150
	151	if (!event) {
	152	ret = -EINVAL;
	153	goto end;
	154	}
	155
	156	uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
	157	if (!uprobe_handler) {
	158	printk(KERN_WARNING "Error allocating uprobe_uprobe_handlers");
	159	ret = -ENOMEM;
	160	goto end;
	161	}
	162
	163	/* Ensure the memory we just allocated don't trigger page faults. */
da0fcb14	164	wrapper_vmalloc_sync_mappings();
3aed4dca FD	165
	166	uprobe_handler->event = event;
	167	uprobe_handler->up_consumer.handler = lttng_uprobes_handler_pre;
	168
	169	ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
	170	if (ret) {
	171	goto register_error;
	172	}
	173
	174	ret = wrapper_uprobe_register(event->u.uprobe.inode,
	175	uprobe_handler->offset, &uprobe_handler->up_consumer);
	176	if (ret) {
	177	printk(KERN_WARNING "Error registering probe on inode %lu "
	178	"and offset 0x%llx\n", event->u.uprobe.inode->i_ino,
	179	uprobe_handler->offset);
	180	ret = -1;
	181	goto register_error;
	182	}
	183
	184	list_add(&uprobe_handler->node, &event->u.uprobe.head);
	185
	186	return ret;
	187
	188	register_error:
	189	kfree(uprobe_handler);
	190	end:
	191	return ret;
	192	}
	193	EXPORT_SYMBOL_GPL(lttng_uprobes_add_callsite);
	194
	195	int lttng_uprobes_register(const char name, int fd, struct lttng_event event)
	196	{
	197	int ret = 0;
56377c91	198	struct inode *inode;
149b9a9d YB	199
	200	ret = lttng_create_uprobe_event(name, event);
	201	if (ret)
	202	goto error;
	203
56377c91 FD	204	inode = get_inode_from_fd(fd);
	205	if (!inode) {
	206	printk(KERN_WARNING "Cannot get inode from fd\n");
	207	ret = -EBADF;
	208	goto inode_error;
	209	}
56377c91	210	event->u.uprobe.inode = inode;
3aed4dca	211	INIT_LIST_HEAD(&event->u.uprobe.head);
149b9a9d	212
149b9a9d YB	213	return 0;
149b9a9d YB	214
56377c91	215	inode_error:
149b9a9d YB	216	kfree(event->desc->name);
	217	kfree(event->desc);
	218	error:
	219	return ret;
	220	}
	221	EXPORT_SYMBOL_GPL(lttng_uprobes_register);
	222
	223	void lttng_uprobes_unregister(struct lttng_event *event)
	224	{
3aed4dca FD	225	struct lttng_uprobe_handler iter, tmp;
	226
	227	/*
	228	* Iterate over the list of handler, remove each handler from the list
	229	* and free the struct.
	230	*/
	231	list_for_each_entry_safe(iter, tmp, &event->u.uprobe.head, node) {
	232	wrapper_uprobe_unregister(event->u.uprobe.inode, iter->offset,
	233	&iter->up_consumer);
	234	list_del(&iter->node);
	235	kfree(iter);
	236	}
149b9a9d YB	237	}
	238	EXPORT_SYMBOL_GPL(lttng_uprobes_unregister);
	239
	240	void lttng_uprobes_destroy_private(struct lttng_event *event)
	241	{
	242	iput(event->u.uprobe.inode);
	243	kfree(event->desc->name);
	244	kfree(event->desc);
	245	}
	246	EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_private);
	247
	248	MODULE_LICENSE("GPL and additional rights");
	249	MODULE_AUTHOR("Yannick Brosseau");
	250	MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");