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

/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
 *
 * probes/lttng-kprobes.c
 *
 * LTTng kprobes integration module.
 *
 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/slab.h>
#include <lttng/events.h>
#include <ringbuffer/frontend_types.h>
#include <wrapper/vmalloc.h>
#include <wrapper/irqflags.h>
#include <lttng/tracer.h>
#include <blacklist/kprobes.h>

static
int lttng_kprobes_event_handler_pre(struct kprobe *p, struct pt_regs *regs)
{
	struct lttng_event *event =
		container_of(p, struct lttng_event, u.kprobe.kp);
	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;
	unsigned long data = (unsigned long) p->addr;

	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(data),
				 lttng_alignof(data), -1);
	ret = chan->ops->event_reserve(&ctx, event->id);
	if (ret < 0)
		return 0;
	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data));
	chan->ops->event_write(&ctx, &data, sizeof(data));
	chan->ops->event_commit(&ctx);
	return 0;
}

static
int lttng_kprobes_event_notifier_handler_pre(struct kprobe *p, struct pt_regs *regs)
{
	struct lttng_event_notifier *event_notifier =
		container_of(p, struct lttng_event_notifier, u.kprobe.kp);

	if (unlikely(!READ_ONCE(event_notifier->enabled)))
		return 0;

	event_notifier->send_notification(event_notifier, NULL, NULL);

	return 0;
}

/*
 * Create event description
 */
static
int lttng_create_kprobe_event(const char *name, struct lttng_event *event)
{
	struct lttng_event_field *field;
	struct lttng_event_desc *desc;
	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 = field =
		kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
	if (!field) {
		ret = -ENOMEM;
		goto error_field;
	}
	field->name = "ip";
	field->type.atype = atype_integer;
	field->type.u.integer.size = sizeof(unsigned long) * CHAR_BIT;
	field->type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	field->type.u.integer.signedness = lttng_is_signed_type(unsigned long);
	field->type.u.integer.reverse_byte_order = 0;
	field->type.u.integer.base = 16;
	field->type.u.integer.encoding = lttng_encode_none;
	desc->owner = THIS_MODULE;
	event->desc = desc;

	return 0;

error_field:
	kfree(desc->name);
error_str:
	kfree(desc);
	return ret;
}

/*
 * Create event_notifier description
 */
static
int lttng_create_kprobe_event_notifier(const char *name, struct lttng_event_notifier *event_notifier)
{
	struct lttng_event_desc *desc;
	int ret;

	desc = kzalloc(sizeof(*event_notifier->desc), GFP_KERNEL);
	if (!desc)
		return -ENOMEM;
	desc->name = kstrdup(name, GFP_KERNEL);
	if (!desc->name) {
		ret = -ENOMEM;
		goto error_str;
	}
	desc->nr_fields = 0;

	desc->owner = THIS_MODULE;
	event_notifier->desc = desc;

	return 0;

error_str:
	kfree(desc);
	return ret;
}

static
int _lttng_kprobes_register(const char *symbol_name,
			   uint64_t offset,
			   uint64_t addr,
			   struct lttng_kprobe *lttng_kp,
			   kprobe_pre_handler_t pre_handler)
{
	int ret;

	/* Kprobes expects a NULL symbol name if unused */
	if (symbol_name[0] == '\0')
		symbol_name = NULL;

	memset(&lttng_kp->kp, 0, sizeof(lttng_kp->kp));
	lttng_kp->kp.pre_handler = pre_handler;

	if (symbol_name) {
		lttng_kp->symbol_name =
			kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
				GFP_KERNEL);
		if (!lttng_kp->symbol_name) {
			ret = -ENOMEM;
			goto name_error;
		}
		memcpy(lttng_kp->symbol_name, symbol_name,
		       LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
		lttng_kp->kp.symbol_name = lttng_kp->symbol_name;
	}

	lttng_kp->kp.offset = offset;
	lttng_kp->kp.addr = (void *) (unsigned long) addr;

	/*
	 * Ensure the memory we just allocated don't event_notifier page faults.
	 * Well.. kprobes itself puts the page fault handler on the blacklist,
	 * but we can never be too careful.
	 */
	wrapper_vmalloc_sync_mappings();

	ret = register_kprobe(&lttng_kp->kp);
	if (ret)
		goto register_error;

	return 0;

register_error:
	kfree(lttng_kp->symbol_name);
name_error:
	return ret;
}

int lttng_kprobes_register_event(const char *name,
			   const char *symbol_name,
			   uint64_t offset,
			   uint64_t addr,
			   struct lttng_event *event)
{
	int ret;

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

	ret = _lttng_kprobes_register(symbol_name, offset, addr,
		&event->u.kprobe, lttng_kprobes_event_handler_pre);
	if (ret)
		goto register_error;

	return 0;

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

int lttng_kprobes_register_event_notifier(const char *symbol_name,
			   uint64_t offset,
			   uint64_t addr,
			   struct lttng_event_notifier *event_notifier)
{
	int ret;
	ret = lttng_create_kprobe_event_notifier(symbol_name, event_notifier);
	if (ret)
		goto error;

	ret = _lttng_kprobes_register(symbol_name, offset, addr,
		&event_notifier->u.kprobe, lttng_kprobes_event_notifier_handler_pre);
	if (ret)
		goto register_error;

	return 0;

register_error:
	kfree(event_notifier->desc->name);
	kfree(event_notifier->desc);
error:
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_kprobes_register_event_notifier);

void lttng_kprobes_unregister_event(struct lttng_event *event)
{
	unregister_kprobe(&event->u.kprobe.kp);
}
EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event);

void lttng_kprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier)
{
	unregister_kprobe(&event_notifier->u.kprobe.kp);
}
EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event_notifier);

void lttng_kprobes_destroy_event_private(struct lttng_event *event)
{
	kfree(event->u.kprobe.symbol_name);
	kfree(event->desc->fields);
	kfree(event->desc->name);
	kfree(event->desc);
}
EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private);

void lttng_kprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier)
{
	kfree(event_notifier->u.kprobe.symbol_name);
	kfree(event_notifier->desc->name);
	kfree(event_notifier->desc);
}
EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private);

MODULE_LICENSE("GPL and additional rights");
MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
MODULE_DESCRIPTION("LTTng kprobes probes");
MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	LTTNG_MODULES_EXTRAVERSION);
Commit	Line	Data
b7cdc182	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
9f36eaed	2	*
886d51a3	3	* probes/lttng-kprobes.c
d6d808f3 MD	4	*
	5	* LTTng kprobes integration module.
	6	*
886d51a3	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
d6d808f3 MD	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/kprobes.h>
f17701fb	12	#include <linux/slab.h>
2df37e95	13	#include <lttng/events.h>
24591303	14	#include <ringbuffer/frontend_types.h>
156a3977 MD	15	#include <wrapper/vmalloc.h>
156a3977 MD	16	#include <wrapper/irqflags.h>
2df37e95	17	#include <lttng/tracer.h>
caa068b5	18	#include <blacklist/kprobes.h>
d6d808f3	19
f17701fb	20	static
8bf17deb	21	int lttng_kprobes_event_handler_pre(struct kprobe p, struct pt_regs regs)
d6d808f3	22	{
a90917c3 MD	23	struct lttng_event *event =
a90917c3 MD	24	container_of(p, struct lttng_event, u.kprobe.kp);
79150a49 JD	25	struct lttng_probe_ctx lttng_probe_ctx = {
79150a49 JD	26	.event = event,
ccecf3fb	27	.interruptible = !lttng_regs_irqs_disabled(regs),
79150a49	28	};
a90917c3	29	struct lttng_channel *chan = event->chan;
d6d808f3 MD	30	struct lib_ring_buffer_ctx ctx;
	31	int ret;
	32	unsigned long data = (unsigned long) p->addr;
	33
585e5dcc	34	if (unlikely(!LTTNG_READ_ONCE(chan->session->active)))
f17701fb	35	return 0;
585e5dcc	36	if (unlikely(!LTTNG_READ_ONCE(chan->enabled)))
e64957da	37	return 0;
585e5dcc	38	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
e64957da MD	39	return 0;
e64957da MD	40
79150a49	41	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx, sizeof(data),
a90917c3	42	lttng_alignof(data), -1);
4e1f08f4	43	ret = chan->ops->event_reserve(&ctx, event->id);
d6d808f3	44	if (ret < 0)
f17701fb	45	return 0;
a90917c3	46	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data));
d6d808f3 MD	47	chan->ops->event_write(&ctx, &data, sizeof(data));
d6d808f3 MD	48	chan->ops->event_commit(&ctx);
f17701fb	49	return 0;
d6d808f3	50	}
f17701fb	51
2b16f0c9 FD	52	static
	53	int lttng_kprobes_event_notifier_handler_pre(struct kprobe p, struct pt_regs regs)
	54	{
	55	struct lttng_event_notifier *event_notifier =
	56	container_of(p, struct lttng_event_notifier, u.kprobe.kp);
	57
	58	if (unlikely(!READ_ONCE(event_notifier->enabled)))
	59	return 0;
	60
99d223ad	61	event_notifier->send_notification(event_notifier, NULL, NULL);
2b16f0c9 FD	62
	63	return 0;
	64	}
	65
f17701fb MD	66	/*
	67	* Create event description
	68	*/
	69	static
a90917c3	70	int lttng_create_kprobe_event(const char name, struct lttng_event event)
f17701fb MD	71	{
f17701fb MD	72	struct lttng_event_field *field;
d3dbe23c	73	struct lttng_event_desc *desc;
f17701fb MD	74	int ret;
f17701fb MD	75
d3dbe23c MD	76	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
d3dbe23c MD	77	if (!desc)
f17701fb	78	return -ENOMEM;
d3dbe23c MD	79	desc->name = kstrdup(name, GFP_KERNEL);
d3dbe23c MD	80	if (!desc->name) {
f17701fb MD	81	ret = -ENOMEM;
	82	goto error_str;
	83	}
d3dbe23c MD	84	desc->nr_fields = 1;
d3dbe23c MD	85	desc->fields = field =
f17701fb	86	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
0d1a681e MD	87	if (!field) {
	88	ret = -ENOMEM;
	89	goto error_field;
	90	}
f17701fb MD	91	field->name = "ip";
f17701fb MD	92	field->type.atype = atype_integer;
ceabb767 MD	93	field->type.u.integer.size = sizeof(unsigned long) * CHAR_BIT;
	94	field->type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	95	field->type.u.integer.signedness = lttng_is_signed_type(unsigned long);
	96	field->type.u.integer.reverse_byte_order = 0;
	97	field->type.u.integer.base = 16;
	98	field->type.u.integer.encoding = lttng_encode_none;
dc7f600a	99	desc->owner = THIS_MODULE;
d3dbe23c	100	event->desc = desc;
f17701fb MD	101
	102	return 0;
	103
0d1a681e MD	104	error_field:
0d1a681e MD	105	kfree(desc->name);
f17701fb	106	error_str:
d3dbe23c	107	kfree(desc);
f17701fb MD	108	return ret;
	109	}
	110
2b16f0c9 FD	111	/*
	112	* Create event_notifier description
	113	*/
	114	static
	115	int lttng_create_kprobe_event_notifier(const char name, struct lttng_event_notifier event_notifier)
	116	{
	117	struct lttng_event_desc *desc;
	118	int ret;
	119
	120	desc = kzalloc(sizeof(*event_notifier->desc), GFP_KERNEL);
	121	if (!desc)
	122	return -ENOMEM;
	123	desc->name = kstrdup(name, GFP_KERNEL);
	124	if (!desc->name) {
	125	ret = -ENOMEM;
	126	goto error_str;
	127	}
	128	desc->nr_fields = 0;
	129
	130	desc->owner = THIS_MODULE;
	131	event_notifier->desc = desc;
	132
	133	return 0;
	134
	135	error_str:
	136	kfree(desc);
	137	return ret;
	138	}
	139
8bf17deb FD	140	static
8bf17deb FD	141	int _lttng_kprobes_register(const char *symbol_name,
f17701fb MD	142	uint64_t offset,
f17701fb MD	143	uint64_t addr,
8bf17deb FD	144	struct lttng_kprobe *lttng_kp,
8bf17deb FD	145	kprobe_pre_handler_t pre_handler)
f17701fb MD	146	{
	147	int ret;
	148
c37f2a9b MD	149	/* Kprobes expects a NULL symbol name if unused */
	150	if (symbol_name[0] == '\0')
	151	symbol_name = NULL;
	152
8bf17deb FD	153	memset(&lttng_kp->kp, 0, sizeof(lttng_kp->kp));
	154	lttng_kp->kp.pre_handler = pre_handler;
	155
c37f2a9b	156	if (symbol_name) {
8bf17deb	157	lttng_kp->symbol_name =
f8695253	158	kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
c37f2a9b	159	GFP_KERNEL);
8bf17deb	160	if (!lttng_kp->symbol_name) {
c37f2a9b MD	161	ret = -ENOMEM;
	162	goto name_error;
	163	}
8bf17deb	164	memcpy(lttng_kp->symbol_name, symbol_name,
f8695253	165	LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
8bf17deb	166	lttng_kp->kp.symbol_name = lttng_kp->symbol_name;
f17701fb	167	}
8bf17deb FD	168
	169	lttng_kp->kp.offset = offset;
	170	lttng_kp->kp.addr = (void *) (unsigned long) addr;
16a9a591 MD	171
16a9a591 MD	172	/*
2b16f0c9	173	* Ensure the memory we just allocated don't event_notifier page faults.
16a9a591 MD	174	* Well.. kprobes itself puts the page fault handler on the blacklist,
	175	* but we can never be too careful.
	176	*/
263b6c88	177	wrapper_vmalloc_sync_mappings();
16a9a591	178
8bf17deb	179	ret = register_kprobe(&lttng_kp->kp);
f17701fb MD	180	if (ret)
f17701fb MD	181	goto register_error;
8bf17deb	182
f17701fb MD	183	return 0;
	184
	185	register_error:
8bf17deb	186	kfree(lttng_kp->symbol_name);
f17701fb	187	name_error:
8bf17deb FD	188	return ret;
	189	}
	190
	191	int lttng_kprobes_register_event(const char *name,
	192	const char *symbol_name,
	193	uint64_t offset,
	194	uint64_t addr,
	195	struct lttng_event *event)
	196	{
	197	int ret;
	198
	199	ret = lttng_create_kprobe_event(name, event);
	200	if (ret)
	201	goto error;
	202
	203	ret = _lttng_kprobes_register(symbol_name, offset, addr,
	204	&event->u.kprobe, lttng_kprobes_event_handler_pre);
	205	if (ret)
	206	goto register_error;
	207
	208	return 0;
	209
	210	register_error:
0d1a681e	211	kfree(event->desc->fields);
f17701fb MD	212	kfree(event->desc->name);
	213	kfree(event->desc);
	214	error:
	215	return ret;
	216	}
8bf17deb	217	EXPORT_SYMBOL_GPL(lttng_kprobes_register_event);
f17701fb	218
2b16f0c9 FD	219	int lttng_kprobes_register_event_notifier(const char *symbol_name,
	220	uint64_t offset,
	221	uint64_t addr,
	222	struct lttng_event_notifier *event_notifier)
	223	{
	224	int ret;
	225	ret = lttng_create_kprobe_event_notifier(symbol_name, event_notifier);
	226	if (ret)
	227	goto error;
	228
	229	ret = _lttng_kprobes_register(symbol_name, offset, addr,
	230	&event_notifier->u.kprobe, lttng_kprobes_event_notifier_handler_pre);
	231	if (ret)
	232	goto register_error;
	233
	234	return 0;
	235
	236	register_error:
	237	kfree(event_notifier->desc->name);
	238	kfree(event_notifier->desc);
	239	error:
	240	return ret;
	241	}
	242	EXPORT_SYMBOL_GPL(lttng_kprobes_register_event_notifier);
	243
8bf17deb	244	void lttng_kprobes_unregister_event(struct lttng_event *event)
f17701fb MD	245	{
f17701fb MD	246	unregister_kprobe(&event->u.kprobe.kp);
edeb3137	247	}
8bf17deb	248	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event);
edeb3137	249
2b16f0c9 FD	250	void lttng_kprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier)
	251	{
	252	unregister_kprobe(&event_notifier->u.kprobe.kp);
	253	}
	254	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event_notifier);
	255
8bf17deb	256	void lttng_kprobes_destroy_event_private(struct lttng_event *event)
edeb3137	257	{
f17701fb	258	kfree(event->u.kprobe.symbol_name);
0d1a681e	259	kfree(event->desc->fields);
f17701fb MD	260	kfree(event->desc->name);
	261	kfree(event->desc);
	262	}
8bf17deb	263	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private);
d6d808f3	264
2b16f0c9 FD	265	void lttng_kprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier)
	266	{
	267	kfree(event_notifier->u.kprobe.symbol_name);
	268	kfree(event_notifier->desc->name);
	269	kfree(event_notifier->desc);
	270	}
	271	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private);
	272
d6d808f3	273	MODULE_LICENSE("GPL and additional rights");
1c124020 MJ	274	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1c124020 MJ	275	MODULE_DESCRIPTION("LTTng kprobes probes");
13ab8b0a MD	276	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	277	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	278	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	279	LTTNG_MODULES_EXTRAVERSION);