[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;
}

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