[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);
	struct lttng_kernel_notifier_ctx notif_ctx;

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

	notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
	event_notifier->send_notification(event_notifier, NULL, NULL, &notif_ctx);

	return 0;
}

static const struct lttng_kernel_type_common *event_type =
	lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16);

/*
 * Create event description
 */
static
int lttng_create_kprobe_event(const char *name, struct lttng_event *event)
{
	const struct lttng_kernel_event_field **fieldp_array;
	struct lttng_kernel_event_field *field;
	struct lttng_kernel_event_desc *desc;
	int ret;

	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
	if (!desc)
		return -ENOMEM;
	desc->event_name = kstrdup(name, GFP_KERNEL);
	if (!desc->event_name) {
		ret = -ENOMEM;
		goto error_str;
	}
	desc->nr_fields = 1;
	fieldp_array = kzalloc(1 * sizeof(struct lttng_kernel_event_field *), GFP_KERNEL);
	if (!fieldp_array) {
		ret = -ENOMEM;
		goto error_fieldp_array;
	}
	desc->fields = fieldp_array;
	desc->fields[0] = field =
		kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL);
	if (!field) {
		ret = -ENOMEM;
		goto error_field;
	}
	field->name = "ip";
	field->type = event_type;
	desc->owner = THIS_MODULE;
	event->desc = desc;

	return 0;

error_field:
	kfree(fieldp_array);
error_fieldp_array:
	kfree(desc->event_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_kernel_event_desc *desc;
	int ret;

	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
	if (!desc)
		return -ENOMEM;
	desc->event_name = kstrdup(name, GFP_KERNEL);
	if (!desc->event_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 notify 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->event_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->event_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[0]);
	kfree(event->desc->fields);
	kfree(event->desc->event_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->event_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);
c3eddb2e	57	struct lttng_kernel_notifier_ctx notif_ctx;
2b16f0c9 FD	58
	59	if (unlikely(!READ_ONCE(event_notifier->enabled)))
	60	return 0;
	61
c3eddb2e MD	62	notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
c3eddb2e MD	63	event_notifier->send_notification(event_notifier, NULL, NULL, &notif_ctx);
2b16f0c9 FD	64
	65	return 0;
	66	}
	67
437d5aa5 MD	68	static const struct lttng_kernel_type_common *event_type =
	69	lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16);
	70
f17701fb MD	71	/*
	72	* Create event description
	73	*/
	74	static
a90917c3	75	int lttng_create_kprobe_event(const char name, struct lttng_event event)
f17701fb	76	{
437d5aa5 MD	77	const struct lttng_kernel_event_field **fieldp_array;
	78	struct lttng_kernel_event_field *field;
	79	struct lttng_kernel_event_desc *desc;
f17701fb MD	80	int ret;
f17701fb MD	81
437d5aa5	82	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
d3dbe23c	83	if (!desc)
f17701fb	84	return -ENOMEM;
437d5aa5 MD	85	desc->event_name = kstrdup(name, GFP_KERNEL);
437d5aa5 MD	86	if (!desc->event_name) {
f17701fb MD	87	ret = -ENOMEM;
	88	goto error_str;
	89	}
d3dbe23c	90	desc->nr_fields = 1;
437d5aa5 MD	91	fieldp_array = kzalloc(1 * sizeof(struct lttng_kernel_event_field *), GFP_KERNEL);
	92	if (!fieldp_array) {
	93	ret = -ENOMEM;
	94	goto error_fieldp_array;
	95	}
	96	desc->fields = fieldp_array;
	97	desc->fields[0] = field =
	98	kzalloc(sizeof(struct lttng_kernel_event_field), GFP_KERNEL);
0d1a681e MD	99	if (!field) {
	100	ret = -ENOMEM;
	101	goto error_field;
	102	}
f17701fb	103	field->name = "ip";
437d5aa5	104	field->type = event_type;
dc7f600a	105	desc->owner = THIS_MODULE;
d3dbe23c	106	event->desc = desc;
f17701fb MD	107
	108	return 0;
	109
0d1a681e	110	error_field:
437d5aa5 MD	111	kfree(fieldp_array);
	112	error_fieldp_array:
	113	kfree(desc->event_name);
f17701fb	114	error_str:
d3dbe23c	115	kfree(desc);
f17701fb MD	116	return ret;
	117	}
	118
2b16f0c9 FD	119	/*
	120	* Create event_notifier description
	121	*/
	122	static
	123	int lttng_create_kprobe_event_notifier(const char name, struct lttng_event_notifier event_notifier)
	124	{
437d5aa5	125	struct lttng_kernel_event_desc *desc;
2b16f0c9 FD	126	int ret;
2b16f0c9 FD	127
437d5aa5	128	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
2b16f0c9 FD	129	if (!desc)
2b16f0c9 FD	130	return -ENOMEM;
437d5aa5 MD	131	desc->event_name = kstrdup(name, GFP_KERNEL);
437d5aa5 MD	132	if (!desc->event_name) {
2b16f0c9 FD	133	ret = -ENOMEM;
	134	goto error_str;
	135	}
	136	desc->nr_fields = 0;
	137
	138	desc->owner = THIS_MODULE;
	139	event_notifier->desc = desc;
	140
	141	return 0;
	142
	143	error_str:
	144	kfree(desc);
	145	return ret;
	146	}
	147
8bf17deb FD	148	static
8bf17deb FD	149	int _lttng_kprobes_register(const char *symbol_name,
f17701fb MD	150	uint64_t offset,
f17701fb MD	151	uint64_t addr,
8bf17deb FD	152	struct lttng_kprobe *lttng_kp,
8bf17deb FD	153	kprobe_pre_handler_t pre_handler)
f17701fb MD	154	{
	155	int ret;
	156
c37f2a9b MD	157	/* Kprobes expects a NULL symbol name if unused */
	158	if (symbol_name[0] == '\0')
	159	symbol_name = NULL;
	160
8bf17deb FD	161	memset(&lttng_kp->kp, 0, sizeof(lttng_kp->kp));
	162	lttng_kp->kp.pre_handler = pre_handler;
	163
c37f2a9b	164	if (symbol_name) {
8bf17deb	165	lttng_kp->symbol_name =
f8695253	166	kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
c37f2a9b	167	GFP_KERNEL);
8bf17deb	168	if (!lttng_kp->symbol_name) {
c37f2a9b MD	169	ret = -ENOMEM;
	170	goto name_error;
	171	}
8bf17deb	172	memcpy(lttng_kp->symbol_name, symbol_name,
f8695253	173	LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
8bf17deb	174	lttng_kp->kp.symbol_name = lttng_kp->symbol_name;
f17701fb	175	}
8bf17deb FD	176
	177	lttng_kp->kp.offset = offset;
	178	lttng_kp->kp.addr = (void *) (unsigned long) addr;
16a9a591 MD	179
16a9a591 MD	180	/*
196bfc6a	181	* Ensure the memory we just allocated don't notify page faults.
16a9a591 MD	182	* Well.. kprobes itself puts the page fault handler on the blacklist,
	183	* but we can never be too careful.
	184	*/
263b6c88	185	wrapper_vmalloc_sync_mappings();
16a9a591	186
8bf17deb	187	ret = register_kprobe(&lttng_kp->kp);
f17701fb MD	188	if (ret)
f17701fb MD	189	goto register_error;
8bf17deb	190
f17701fb MD	191	return 0;
	192
	193	register_error:
8bf17deb	194	kfree(lttng_kp->symbol_name);
f17701fb	195	name_error:
8bf17deb FD	196	return ret;
	197	}
	198
	199	int lttng_kprobes_register_event(const char *name,
	200	const char *symbol_name,
	201	uint64_t offset,
	202	uint64_t addr,
	203	struct lttng_event *event)
	204	{
	205	int ret;
	206
	207	ret = lttng_create_kprobe_event(name, event);
	208	if (ret)
	209	goto error;
	210
	211	ret = _lttng_kprobes_register(symbol_name, offset, addr,
	212	&event->u.kprobe, lttng_kprobes_event_handler_pre);
	213	if (ret)
	214	goto register_error;
	215
	216	return 0;
	217
	218	register_error:
0d1a681e	219	kfree(event->desc->fields);
437d5aa5	220	kfree(event->desc->event_name);
f17701fb MD	221	kfree(event->desc);
	222	error:
	223	return ret;
	224	}
8bf17deb	225	EXPORT_SYMBOL_GPL(lttng_kprobes_register_event);
f17701fb	226
2b16f0c9 FD	227	int lttng_kprobes_register_event_notifier(const char *symbol_name,
	228	uint64_t offset,
	229	uint64_t addr,
	230	struct lttng_event_notifier *event_notifier)
	231	{
	232	int ret;
	233	ret = lttng_create_kprobe_event_notifier(symbol_name, event_notifier);
	234	if (ret)
	235	goto error;
	236
	237	ret = _lttng_kprobes_register(symbol_name, offset, addr,
	238	&event_notifier->u.kprobe, lttng_kprobes_event_notifier_handler_pre);
	239	if (ret)
	240	goto register_error;
	241
	242	return 0;
	243
	244	register_error:
437d5aa5	245	kfree(event_notifier->desc->event_name);
2b16f0c9 FD	246	kfree(event_notifier->desc);
	247	error:
	248	return ret;
	249	}
	250	EXPORT_SYMBOL_GPL(lttng_kprobes_register_event_notifier);
	251
8bf17deb	252	void lttng_kprobes_unregister_event(struct lttng_event *event)
f17701fb MD	253	{
f17701fb MD	254	unregister_kprobe(&event->u.kprobe.kp);
edeb3137	255	}
8bf17deb	256	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event);
edeb3137	257
2b16f0c9 FD	258	void lttng_kprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier)
	259	{
	260	unregister_kprobe(&event_notifier->u.kprobe.kp);
	261	}
	262	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event_notifier);
	263
8bf17deb	264	void lttng_kprobes_destroy_event_private(struct lttng_event *event)
edeb3137	265	{
f17701fb	266	kfree(event->u.kprobe.symbol_name);
437d5aa5	267	kfree(event->desc->fields[0]);
0d1a681e	268	kfree(event->desc->fields);
437d5aa5	269	kfree(event->desc->event_name);
f17701fb MD	270	kfree(event->desc);
f17701fb MD	271	}
8bf17deb	272	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private);
d6d808f3	273
2b16f0c9 FD	274	void lttng_kprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier)
	275	{
	276	kfree(event_notifier->u.kprobe.symbol_name);
437d5aa5	277	kfree(event_notifier->desc->event_name);
2b16f0c9 FD	278	kfree(event_notifier->desc);
	279	}
	280	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private);
	281
d6d808f3	282	MODULE_LICENSE("GPL and additional rights");
1c124020 MJ	283	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1c124020 MJ	284	MODULE_DESCRIPTION("LTTng kprobes probes");
13ab8b0a MD	285	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	286	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	287	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	288	LTTNG_MODULES_EXTRAVERSION);