[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 <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 <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_event *event = uprobe_handler->u.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(!LTTNG_READ_ONCE(chan->session->active)))
		return 0;
	if (unlikely(!LTTNG_READ_ONCE(chan->enabled)))
		return 0;
	if (unlikely(!LTTNG_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.integer.size = sizeof(unsigned long) * CHAR_BIT;
	fields[0].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	fields[0].type.u.integer.signedness = lttng_is_signed_type(unsigned long);
	fields[0].type.u.integer.reverse_byte_order = 0;
	fields[0].type.u.integer.base = 16;
	fields[0].type.u.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 "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_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 trigger page faults. */
	wrapper_vmalloc_sync_mappings();

	uprobe_handler->u.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_event *event,
	struct lttng_kernel_event_callsite __user *callsite)
{
	return lttng_uprobes_add_callsite(&event->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_event *event)
{
	int ret = 0;

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

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

	return 0;

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

void lttng_uprobes_unregister_event(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_event);

void lttng_uprobes_destroy_event_private(struct lttng_event *event)
{
	iput(event->u.uprobe.inode);
	kfree(event->desc->name);
	kfree(event->desc);
}
EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_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	*/
	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>
2df37e95 MD	18	#include <lttng/events.h>
2df37e95 MD	19	#include <lttng/tracer.h>
149b9a9d	20	#include <wrapper/irqflags.h>
24591303	21	#include <ringbuffer/frontend_types.h>
149b9a9d YB	22	#include <wrapper/uprobes.h>
	23	#include <wrapper/vmalloc.h>
	24
	25	static
83b802dc	26	int lttng_uprobes_event_handler_pre(struct uprobe_consumer uc, struct pt_regs regs)
149b9a9d	27	{
3aed4dca FD	28	struct lttng_uprobe_handler *uprobe_handler =
3aed4dca FD	29	container_of(uc, struct lttng_uprobe_handler, up_consumer);
83b802dc	30	struct lttng_event *event = uprobe_handler->u.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
585e5dcc	43	if (unlikely(!LTTNG_READ_ONCE(chan->session->active)))
149b9a9d	44	return 0;
585e5dcc	45	if (unlikely(!LTTNG_READ_ONCE(chan->enabled)))
149b9a9d	46	return 0;
585e5dcc	47	if (unlikely(!LTTNG_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;
ceabb767 MD	95	fields[0].type.u.integer.size = sizeof(unsigned long) * CHAR_BIT;
	96	fields[0].type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	97	fields[0].type.u.integer.signedness = lttng_is_signed_type(unsigned long);
	98	fields[0].type.u.integer.reverse_byte_order = 0;
	99	fields[0].type.u.integer.base = 16;
	100	fields[0].type.u.integer.encoding = lttng_encode_none;
149b9a9d YB	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) {
5a15f70c	131	printk(KERN_WARNING "LTTng: Cannot access file backing the fd(%d)\n", fd);
56377c91 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)
5a15f70c	139	printk(KERN_WARNING "LTTng: Cannot grab a reference on the inode.\n");
56377c91 FD	140	error:
	141	rcu_read_unlock();
	142	return inode;
	143	}
	144
83b802dc FD	145
	146	static
	147	int lttng_uprobes_add_callsite(struct lttng_uprobe *uprobe,
	148	struct lttng_kernel_event_callsite __user *callsite,
	149	int (handler)(struct uprobe_consumer self, struct pt_regs *regs),
	150	void *priv_data)
149b9a9d	151	{
3aed4dca FD	152	int ret = 0;
	153	struct lttng_uprobe_handler *uprobe_handler;
	154
83b802dc	155	if (!priv_data) {
3aed4dca FD	156	ret = -EINVAL;
	157	goto end;
	158	}
	159
	160	uprobe_handler = kzalloc(sizeof(struct lttng_uprobe_handler), GFP_KERNEL);
	161	if (!uprobe_handler) {
5a15f70c	162	printk(KERN_WARNING "LTTng: Error allocating uprobe_handler");
3aed4dca FD	163	ret = -ENOMEM;
	164	goto end;
	165	}
	166
	167	/* Ensure the memory we just allocated don't trigger page faults. */
263b6c88	168	wrapper_vmalloc_sync_mappings();
3aed4dca	169
83b802dc FD	170	uprobe_handler->u.event = priv_data;
83b802dc FD	171	uprobe_handler->up_consumer.handler = handler;
3aed4dca FD	172
	173	ret = copy_from_user(&uprobe_handler->offset, &callsite->u.uprobe.offset, sizeof(uint64_t));
	174	if (ret) {
	175	goto register_error;
	176	}
	177
83b802dc	178	ret = wrapper_uprobe_register(uprobe->inode,
3aed4dca FD	179	uprobe_handler->offset, &uprobe_handler->up_consumer);
3aed4dca FD	180	if (ret) {
5a15f70c	181	printk(KERN_WARNING "LTTng: Error registering probe on inode %lu "
83b802dc	182	"and offset 0x%llx\n", uprobe->inode->i_ino,
3aed4dca FD	183	uprobe_handler->offset);
	184	ret = -1;
	185	goto register_error;
	186	}
	187
83b802dc	188	list_add(&uprobe_handler->node, &uprobe->head);
3aed4dca FD	189
	190	return ret;
	191
	192	register_error:
	193	kfree(uprobe_handler);
	194	end:
	195	return ret;
	196	}
3aed4dca	197
83b802dc FD	198	int lttng_uprobes_event_add_callsite(struct lttng_event *event,
	199	struct lttng_kernel_event_callsite __user *callsite)
	200	{
	201	return lttng_uprobes_add_callsite(&event->u.uprobe, callsite,
	202	lttng_uprobes_event_handler_pre, event);
	203	}
	204	EXPORT_SYMBOL_GPL(lttng_uprobes_event_add_callsite);
	205
	206	static
	207	int lttng_uprobes_register(struct lttng_uprobe *uprobe, int fd)
3aed4dca FD	208	{
3aed4dca FD	209	int ret = 0;
56377c91	210	struct inode *inode;
149b9a9d	211
56377c91 FD	212	inode = get_inode_from_fd(fd);
56377c91 FD	213	if (!inode) {
5a15f70c	214	printk(KERN_WARNING "LTTng: Cannot get inode from fd\n");
56377c91 FD	215	ret = -EBADF;
	216	goto inode_error;
	217	}
83b802dc FD	218	uprobe->inode = inode;
	219	INIT_LIST_HEAD(&uprobe->head);
	220
	221	inode_error:
	222	return ret;
	223	}
	224
	225	int lttng_uprobes_register_event(const char name, int fd, struct lttng_event event)
	226	{
	227	int ret = 0;
	228
	229	ret = lttng_create_uprobe_event(name, event);
	230	if (ret)
	231	goto error;
	232
	233	ret = lttng_uprobes_register(&event->u.uprobe, fd);
	234	if (ret)
	235	goto register_error;
149b9a9d	236
149b9a9d YB	237	return 0;
149b9a9d YB	238
83b802dc	239	register_error:
149b9a9d YB	240	kfree(event->desc->name);
	241	kfree(event->desc);
	242	error:
	243	return ret;
	244	}
83b802dc	245	EXPORT_SYMBOL_GPL(lttng_uprobes_register_event);
149b9a9d	246
83b802dc	247	void lttng_uprobes_unregister_event(struct lttng_event *event)
149b9a9d	248	{
3aed4dca FD	249	struct lttng_uprobe_handler iter, tmp;
	250
	251	/*
	252	* Iterate over the list of handler, remove each handler from the list
	253	* and free the struct.
	254	*/
	255	list_for_each_entry_safe(iter, tmp, &event->u.uprobe.head, node) {
	256	wrapper_uprobe_unregister(event->u.uprobe.inode, iter->offset,
	257	&iter->up_consumer);
	258	list_del(&iter->node);
	259	kfree(iter);
	260	}
149b9a9d	261	}
83b802dc	262	EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event);
149b9a9d	263
83b802dc	264	void lttng_uprobes_destroy_event_private(struct lttng_event *event)
149b9a9d YB	265	{
	266	iput(event->u.uprobe.inode);
	267	kfree(event->desc->name);
	268	kfree(event->desc);
	269	}
83b802dc	270	EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_private);
149b9a9d YB	271
	272	MODULE_LICENSE("GPL and additional rights");
	273	MODULE_AUTHOR("Yannick Brosseau");
	274	MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");