[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 <lttng/events-internal.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_kernel_event_common_private *event_priv =
		container_of(p, struct lttng_kernel_event_common_private, u.kprobe.kp);
	struct lttng_kernel_event_common *event = event_priv->pub;
	struct lttng_kernel_probe_ctx lttng_probe_ctx = {
		.event = event,
		.interruptible = !lttng_regs_irqs_disabled(regs),
	};
	unsigned long data = (unsigned long) p->addr;

	switch (event->type) {
	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	{
		struct lttng_kernel_event_recorder_private *event_recorder_priv =
			container_of(event_priv, struct lttng_kernel_event_recorder_private, parent);
		struct lttng_kernel_event_recorder *event_recorder =
			event_recorder_priv->pub;
		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(data),
					 lttng_alignof(data), &lttng_probe_ctx);
		ret = chan->ops->event_reserve(&ctx);
		if (ret < 0)
			return 0;
		chan->ops->event_write(&ctx, &data, sizeof(data), lttng_alignof(data));
		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_kprobe_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;
}

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_ABI_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_ABI_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_kernel_event_common *event)
{
	int ret;

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

	ret = _lttng_kprobes_register(symbol_name, offset, addr,
		&event->priv->u.kprobe, lttng_kprobes_event_handler_pre);
	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_kprobes_register_event);

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

void lttng_kprobes_destroy_event_private(struct lttng_kernel_event_common *event)
{
	kfree(event->priv->u.kprobe.symbol_name);
	kfree(event->priv->desc->event_name);
	kfree(event->priv->desc);
}
EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_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>
a67ba386	14	#include <lttng/events-internal.h>
24591303	15	#include <ringbuffer/frontend_types.h>
156a3977 MD	16	#include <wrapper/vmalloc.h>
156a3977 MD	17	#include <wrapper/irqflags.h>
2df37e95	18	#include <lttng/tracer.h>
caa068b5	19	#include <blacklist/kprobes.h>
d6d808f3	20
f17701fb	21	static
8bf17deb	22	int lttng_kprobes_event_handler_pre(struct kprobe p, struct pt_regs regs)
d6d808f3	23	{
a67ba386 MD	24	struct lttng_kernel_event_common_private *event_priv =
a67ba386 MD	25	container_of(p, struct lttng_kernel_event_common_private, u.kprobe.kp);
e2d5dbc7	26	struct lttng_kernel_event_common *event = event_priv->pub;
a92e844e	27	struct lttng_kernel_probe_ctx lttng_probe_ctx = {
e2d5dbc7	28	.event = event,
ccecf3fb	29	.interruptible = !lttng_regs_irqs_disabled(regs),
79150a49	30	};
d6d808f3 MD	31	unsigned long data = (unsigned long) p->addr;
d6d808f3 MD	32
e2d5dbc7 MD	33	switch (event->type) {
	34	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	35	{
	36	struct lttng_kernel_event_recorder_private *event_recorder_priv =
	37	container_of(event_priv, struct lttng_kernel_event_recorder_private, parent);
	38	struct lttng_kernel_event_recorder *event_recorder =
	39	event_recorder_priv->pub;
f7d06400	40	struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
e2d5dbc7	41
f7d06400	42	if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active)))
e2d5dbc7	43	return 0;
f7d06400	44	if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled)))
e2d5dbc7 MD	45	return 0;
	46	break;
	47	}
	48	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
	49	break;
	50	default:
	51	WARN_ON_ONCE(1);
	52	}
a67ba386	53
e2d5dbc7	54	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
2b16f0c9 FD	55	return 0;
2b16f0c9 FD	56
e2d5dbc7 MD	57	switch (event->type) {
	58	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
	59	{
	60	struct lttng_kernel_event_recorder *event_recorder =
	61	container_of(event, struct lttng_kernel_event_recorder, parent);
f7d06400	62	struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
8a57ec02	63	struct lttng_kernel_ring_buffer_ctx ctx;
e2d5dbc7 MD	64	int ret;
e2d5dbc7 MD	65
b1199bd3 MD	66	lib_ring_buffer_ctx_init(&ctx, event_recorder, sizeof(data),
b1199bd3 MD	67	lttng_alignof(data), &lttng_probe_ctx);
c2fb9c1c	68	ret = chan->ops->event_reserve(&ctx);
e2d5dbc7 MD	69	if (ret < 0)
e2d5dbc7 MD	70	return 0;
f5ffbd77	71	chan->ops->event_write(&ctx, &data, sizeof(data), lttng_alignof(data));
e2d5dbc7 MD	72	chan->ops->event_commit(&ctx);
	73	break;
	74	}
	75	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
	76	{
	77	struct lttng_kernel_event_notifier *event_notifier =
	78	container_of(event, struct lttng_kernel_event_notifier, parent);
	79	struct lttng_kernel_notification_ctx notif_ctx;
	80
	81	notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
	82	event_notifier->notification_send(event_notifier, NULL, NULL, &notif_ctx);
	83	break;
	84	}
	85	default:
	86	WARN_ON_ONCE(1);
	87	}
2b16f0c9 FD	88	return 0;
	89	}
	90
6c8c025b MD	91	static const struct lttng_kernel_event_field *event_fields[] = {
	92	lttng_kernel_static_event_field("ip",
	93	lttng_kernel_static_type_integer_from_type(unsigned long, __BYTE_ORDER, 16),
	94	false, false, false),
	95	};
	96
	97	static const struct lttng_kernel_tracepoint_class tp_class = {
	98	.nr_fields = ARRAY_SIZE(event_fields),
	99	.fields = event_fields,
	100	};
437d5aa5	101
f17701fb MD	102	/*
	103	* Create event description
	104	*/
	105	static
6a35e5bd	106	int lttng_create_kprobe_event(const char name, struct lttng_kernel_event_common event)
f17701fb	107	{
437d5aa5	108	struct lttng_kernel_event_desc *desc;
f17701fb MD	109	int ret;
f17701fb MD	110
437d5aa5	111	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
d3dbe23c	112	if (!desc)
f17701fb	113	return -ENOMEM;
6c8c025b	114	desc->tp_class = &tp_class;
437d5aa5 MD	115	desc->event_name = kstrdup(name, GFP_KERNEL);
437d5aa5 MD	116	if (!desc->event_name) {
f17701fb MD	117	ret = -ENOMEM;
	118	goto error_str;
	119	}
dc7f600a	120	desc->owner = THIS_MODULE;
6a35e5bd	121	event->priv->desc = desc;
2b16f0c9 FD	122
	123	return 0;
	124
	125	error_str:
	126	kfree(desc);
	127	return ret;
	128	}
	129
8bf17deb FD	130	static
8bf17deb FD	131	int _lttng_kprobes_register(const char *symbol_name,
f17701fb MD	132	uint64_t offset,
f17701fb MD	133	uint64_t addr,
8bf17deb FD	134	struct lttng_kprobe *lttng_kp,
8bf17deb FD	135	kprobe_pre_handler_t pre_handler)
f17701fb MD	136	{
	137	int ret;
	138
c37f2a9b MD	139	/* Kprobes expects a NULL symbol name if unused */
	140	if (symbol_name[0] == '\0')
	141	symbol_name = NULL;
	142
8bf17deb FD	143	memset(&lttng_kp->kp, 0, sizeof(lttng_kp->kp));
	144	lttng_kp->kp.pre_handler = pre_handler;
	145
c37f2a9b	146	if (symbol_name) {
8bf17deb	147	lttng_kp->symbol_name =
606828e4	148	kzalloc(LTTNG_KERNEL_ABI_SYM_NAME_LEN * sizeof(char),
c37f2a9b	149	GFP_KERNEL);
8bf17deb	150	if (!lttng_kp->symbol_name) {
c37f2a9b MD	151	ret = -ENOMEM;
	152	goto name_error;
	153	}
8bf17deb	154	memcpy(lttng_kp->symbol_name, symbol_name,
606828e4	155	LTTNG_KERNEL_ABI_SYM_NAME_LEN * sizeof(char));
8bf17deb	156	lttng_kp->kp.symbol_name = lttng_kp->symbol_name;
f17701fb	157	}
8bf17deb FD	158
	159	lttng_kp->kp.offset = offset;
	160	lttng_kp->kp.addr = (void *) (unsigned long) addr;
16a9a591 MD	161
16a9a591 MD	162	/*
196bfc6a	163	* Ensure the memory we just allocated don't notify page faults.
16a9a591 MD	164	* Well.. kprobes itself puts the page fault handler on the blacklist,
	165	* but we can never be too careful.
	166	*/
263b6c88	167	wrapper_vmalloc_sync_mappings();
16a9a591	168
8bf17deb	169	ret = register_kprobe(&lttng_kp->kp);
f17701fb MD	170	if (ret)
f17701fb MD	171	goto register_error;
8bf17deb	172
f17701fb MD	173	return 0;
	174
	175	register_error:
8bf17deb	176	kfree(lttng_kp->symbol_name);
f17701fb	177	name_error:
8bf17deb FD	178	return ret;
	179	}
	180
	181	int lttng_kprobes_register_event(const char *name,
	182	const char *symbol_name,
	183	uint64_t offset,
	184	uint64_t addr,
6a35e5bd	185	struct lttng_kernel_event_common *event)
8bf17deb FD	186	{
	187	int ret;
	188
6a35e5bd	189	ret = lttng_create_kprobe_event(name, event);
8bf17deb FD	190	if (ret)
	191	goto error;
	192
	193	ret = _lttng_kprobes_register(symbol_name, offset, addr,
6a35e5bd	194	&event->priv->u.kprobe, lttng_kprobes_event_handler_pre);
8bf17deb FD	195	if (ret)
	196	goto register_error;
	197
	198	return 0;
	199
	200	register_error:
6a35e5bd MD	201	kfree(event->priv->desc->event_name);
6a35e5bd MD	202	kfree(event->priv->desc);
f17701fb MD	203	error:
	204	return ret;
	205	}
8bf17deb	206	EXPORT_SYMBOL_GPL(lttng_kprobes_register_event);
f17701fb	207
6a35e5bd	208	void lttng_kprobes_unregister_event(struct lttng_kernel_event_common *event)
f17701fb	209	{
6a35e5bd	210	unregister_kprobe(&event->priv->u.kprobe.kp);
edeb3137	211	}
8bf17deb	212	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event);
edeb3137	213
6a35e5bd	214	void lttng_kprobes_destroy_event_private(struct lttng_kernel_event_common *event)
2b16f0c9	215	{
6a35e5bd MD	216	kfree(event->priv->u.kprobe.symbol_name);
	217	kfree(event->priv->desc->event_name);
	218	kfree(event->priv->desc);
f17701fb	219	}
8bf17deb	220	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private);
d6d808f3 MD	221
d6d808f3 MD	222	MODULE_LICENSE("GPL and additional rights");
1c124020 MJ	223	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1c124020 MJ	224	MODULE_DESCRIPTION("LTTng kprobes probes");
13ab8b0a MD	225	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	226	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	227	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	228	LTTNG_MODULES_EXTRAVERSION);