[deliverable/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_event_container *container = event->container;
	int ret;
	unsigned long data = (unsigned long) p->addr;

	if (unlikely(!LTTNG_READ_ONCE(container->session->active)))
		return 0;
	if (unlikely(!LTTNG_READ_ONCE(container->enabled)))
		return 0;
	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
		return 0;

	switch (container->type) {
	case LTTNG_EVENT_CONTAINER_CHANNEL:
	{
		struct lttng_channel *chan = lttng_event_container_get_channel(container);
		struct lib_ring_buffer_ctx ctx;

		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);
		break;
	}
	case LTTNG_EVENT_CONTAINER_COUNTER:
	{
		struct lttng_counter *counter = lttng_event_container_get_counter(container);
		size_t index = event->id;

		(void) counter->ops->counter_add(counter->counter, &index, 1);
		break;
	}
	}
	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;
}

/*
 * 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
	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
	2	*
	3	* probes/lttng-kprobes.c
	4	*
	5	* LTTng kprobes integration module.
	6	*
	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/kprobes.h>
	12	#include <linux/slab.h>
	13	#include <lttng/events.h>
	14	#include <ringbuffer/frontend_types.h>
	15	#include <wrapper/vmalloc.h>
	16	#include <wrapper/irqflags.h>
	17	#include <lttng/tracer.h>
	18	#include <blacklist/kprobes.h>
	19
	20	static
	21	int lttng_kprobes_event_handler_pre(struct kprobe p, struct pt_regs regs)
	22	{
	23	struct lttng_event *event =
	24	container_of(p, struct lttng_event, u.kprobe.kp);
	25	struct lttng_probe_ctx lttng_probe_ctx = {
	26	.event = event,
	27	.interruptible = !lttng_regs_irqs_disabled(regs),
	28	};
	29	struct lttng_event_container *container = event->container;
	30	int ret;
	31	unsigned long data = (unsigned long) p->addr;
	32
	33	if (unlikely(!LTTNG_READ_ONCE(container->session->active)))
	34	return 0;
	35	if (unlikely(!LTTNG_READ_ONCE(container->enabled)))
	36	return 0;
	37	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
	38	return 0;
	39
	40	switch (container->type) {
	41	case LTTNG_EVENT_CONTAINER_CHANNEL:
	42	{
	43	struct lttng_channel *chan = lttng_event_container_get_channel(container);
	44	struct lib_ring_buffer_ctx ctx;
	45
	46	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx, sizeof(data),
	47	lttng_alignof(data), -1);
	48	ret = chan->ops->event_reserve(&ctx, event->id);
	49	if (ret < 0)
	50	return 0;
	51	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data));
	52	chan->ops->event_write(&ctx, &data, sizeof(data));
	53	chan->ops->event_commit(&ctx);
	54	break;
	55	}
	56	case LTTNG_EVENT_CONTAINER_COUNTER:
	57	{
	58	struct lttng_counter *counter = lttng_event_container_get_counter(container);
	59	size_t index = event->id;
	60
	61	(void) counter->ops->counter_add(counter->counter, &index, 1);
	62	break;
	63	}
	64	}
	65	return 0;
	66	}
	67
	68	static
	69	int lttng_kprobes_event_notifier_handler_pre(struct kprobe p, struct pt_regs regs)
	70	{
	71	struct lttng_event_notifier *event_notifier =
	72	container_of(p, struct lttng_event_notifier, u.kprobe.kp);
	73	struct lttng_kernel_notifier_ctx notif_ctx;
	74
	75	if (unlikely(!READ_ONCE(event_notifier->enabled)))
	76	return 0;
	77
	78	notif_ctx.eval_capture = LTTNG_READ_ONCE(event_notifier->eval_capture);
	79	event_notifier->send_notification(event_notifier, NULL, NULL, &notif_ctx);
	80
	81	return 0;
	82	}
	83
	84	/*
	85	* Create event description
	86	*/
	87	static
	88	int lttng_create_kprobe_event(const char name, struct lttng_event event)
	89	{
	90	struct lttng_event_field *field;
	91	struct lttng_event_desc *desc;
	92	int ret;
	93
	94	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	95	if (!desc)
	96	return -ENOMEM;
	97	desc->name = kstrdup(name, GFP_KERNEL);
	98	if (!desc->name) {
	99	ret = -ENOMEM;
	100	goto error_str;
	101	}
	102	desc->nr_fields = 1;
	103	desc->fields = field =
	104	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
	105	if (!field) {
	106	ret = -ENOMEM;
	107	goto error_field;
	108	}
	109	field->name = "ip";
	110	field->type.atype = atype_integer;
	111	field->type.u.integer.size = sizeof(unsigned long) * CHAR_BIT;
	112	field->type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	113	field->type.u.integer.signedness = lttng_is_signed_type(unsigned long);
	114	field->type.u.integer.reverse_byte_order = 0;
	115	field->type.u.integer.base = 16;
	116	field->type.u.integer.encoding = lttng_encode_none;
	117	desc->owner = THIS_MODULE;
	118	event->desc = desc;
	119
	120	return 0;
	121
	122	error_field:
	123	kfree(desc->name);
	124	error_str:
	125	kfree(desc);
	126	return ret;
	127	}
	128
	129	/*
	130	* Create event_notifier description
	131	*/
	132	static
	133	int lttng_create_kprobe_event_notifier(const char name, struct lttng_event_notifier event_notifier)
	134	{
	135	struct lttng_event_desc *desc;
	136	int ret;
	137
	138	desc = kzalloc(sizeof(*event_notifier->desc), GFP_KERNEL);
	139	if (!desc)
	140	return -ENOMEM;
	141	desc->name = kstrdup(name, GFP_KERNEL);
	142	if (!desc->name) {
	143	ret = -ENOMEM;
	144	goto error_str;
	145	}
	146	desc->nr_fields = 0;
	147
	148	desc->owner = THIS_MODULE;
	149	event_notifier->desc = desc;
	150
	151	return 0;
	152
	153	error_str:
	154	kfree(desc);
	155	return ret;
	156	}
	157
	158	static
	159	int _lttng_kprobes_register(const char *symbol_name,
	160	uint64_t offset,
	161	uint64_t addr,
	162	struct lttng_kprobe *lttng_kp,
	163	kprobe_pre_handler_t pre_handler)
	164	{
	165	int ret;
	166
	167	/* Kprobes expects a NULL symbol name if unused */
	168	if (symbol_name[0] == '\0')
	169	symbol_name = NULL;
	170
	171	memset(&lttng_kp->kp, 0, sizeof(lttng_kp->kp));
	172	lttng_kp->kp.pre_handler = pre_handler;
	173
	174	if (symbol_name) {
	175	lttng_kp->symbol_name =
	176	kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
	177	GFP_KERNEL);
	178	if (!lttng_kp->symbol_name) {
	179	ret = -ENOMEM;
	180	goto name_error;
	181	}
	182	memcpy(lttng_kp->symbol_name, symbol_name,
	183	LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
	184	lttng_kp->kp.symbol_name = lttng_kp->symbol_name;
	185	}
	186
	187	lttng_kp->kp.offset = offset;
	188	lttng_kp->kp.addr = (void *) (unsigned long) addr;
	189
	190	/*
	191	* Ensure the memory we just allocated don't event_notifier page faults.
	192	* Well.. kprobes itself puts the page fault handler on the blacklist,
	193	* but we can never be too careful.
	194	*/
	195	wrapper_vmalloc_sync_mappings();
	196
	197	ret = register_kprobe(&lttng_kp->kp);
	198	if (ret)
	199	goto register_error;
	200
	201	return 0;
	202
	203	register_error:
	204	kfree(lttng_kp->symbol_name);
	205	name_error:
	206	return ret;
	207	}
	208
	209	int lttng_kprobes_register_event(const char *name,
	210	const char *symbol_name,
	211	uint64_t offset,
	212	uint64_t addr,
	213	struct lttng_event *event)
	214	{
	215	int ret;
	216
	217	ret = lttng_create_kprobe_event(name, event);
	218	if (ret)
	219	goto error;
	220
	221	ret = _lttng_kprobes_register(symbol_name, offset, addr,
	222	&event->u.kprobe, lttng_kprobes_event_handler_pre);
	223	if (ret)
	224	goto register_error;
	225
	226	return 0;
	227
	228	register_error:
	229	kfree(event->desc->fields);
	230	kfree(event->desc->name);
	231	kfree(event->desc);
	232	error:
	233	return ret;
	234	}
	235	EXPORT_SYMBOL_GPL(lttng_kprobes_register_event);
	236
	237	int lttng_kprobes_register_event_notifier(const char *symbol_name,
	238	uint64_t offset,
	239	uint64_t addr,
	240	struct lttng_event_notifier *event_notifier)
	241	{
	242	int ret;
	243	ret = lttng_create_kprobe_event_notifier(symbol_name, event_notifier);
	244	if (ret)
	245	goto error;
	246
	247	ret = _lttng_kprobes_register(symbol_name, offset, addr,
	248	&event_notifier->u.kprobe, lttng_kprobes_event_notifier_handler_pre);
	249	if (ret)
	250	goto register_error;
	251
	252	return 0;
	253
	254	register_error:
	255	kfree(event_notifier->desc->name);
	256	kfree(event_notifier->desc);
	257	error:
	258	return ret;
	259	}
	260	EXPORT_SYMBOL_GPL(lttng_kprobes_register_event_notifier);
	261
	262	void lttng_kprobes_unregister_event(struct lttng_event *event)
	263	{
	264	unregister_kprobe(&event->u.kprobe.kp);
	265	}
	266	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event);
	267
	268	void lttng_kprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier)
	269	{
	270	unregister_kprobe(&event_notifier->u.kprobe.kp);
	271	}
	272	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event_notifier);
	273
	274	void lttng_kprobes_destroy_event_private(struct lttng_event *event)
	275	{
	276	kfree(event->u.kprobe.symbol_name);
	277	kfree(event->desc->fields);
	278	kfree(event->desc->name);
	279	kfree(event->desc);
	280	}
	281	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private);
	282
	283	void lttng_kprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier)
	284	{
	285	kfree(event_notifier->u.kprobe.symbol_name);
	286	kfree(event_notifier->desc->name);
	287	kfree(event_notifier->desc);
	288	}
	289	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private);
	290
	291	MODULE_LICENSE("GPL and additional rights");
	292	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
	293	MODULE_DESCRIPTION("LTTng kprobes probes");
	294	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	295	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	296	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	297	LTTNG_MODULES_EXTRAVERSION);