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

/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
 *
 * 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 <wrapper/ringbuffer/frontend_types.h>
#include <wrapper/vmalloc.h>
#include <wrapper/irqflags.h>
#include <lttng-tracer.h>

static
int lttng_kprobes_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(!READ_ONCE(chan->session->active)))
		return 0;
	if (unlikely(!READ_ONCE(chan->enabled)))
		return 0;
	if (unlikely(!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;
}

/*
 * 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.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	field->type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	field->type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	field->type.u.basic.integer.reverse_byte_order = 0;
	field->type.u.basic.integer.base = 16;
	field->type.u.basic.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;
}

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

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

	ret = lttng_create_kprobe_event(name, event);
	if (ret)
		goto error;
	memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
	event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
	if (symbol_name) {
		event->u.kprobe.symbol_name =
			kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
				GFP_KERNEL);
		if (!event->u.kprobe.symbol_name) {
			ret = -ENOMEM;
			goto name_error;
		}
		memcpy(event->u.kprobe.symbol_name, symbol_name,
		       LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
		event->u.kprobe.kp.symbol_name =
			event->u.kprobe.symbol_name;
	}
	event->u.kprobe.kp.offset = offset;
	event->u.kprobe.kp.addr = (void *) (unsigned long) addr;

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

	ret = register_kprobe(&event->u.kprobe.kp);
	if (ret)
		goto register_error;
	return 0;

register_error:
	kfree(event->u.kprobe.symbol_name);
name_error:
	kfree(event->desc->fields);
	kfree(event->desc->name);
	kfree(event->desc);
error:
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_kprobes_register);

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

void lttng_kprobes_destroy_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_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
9f36eaed MJ	1	/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
9f36eaed MJ	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>
156a3977 MD	13	#include <lttng-events.h>
	14	#include <wrapper/ringbuffer/frontend_types.h>
	15	#include <wrapper/vmalloc.h>
	16	#include <wrapper/irqflags.h>
	17	#include <lttng-tracer.h>
d6d808f3	18
f17701fb MD	19	static
f17701fb MD	20	int lttng_kprobes_handler_pre(struct kprobe p, struct pt_regs regs)
d6d808f3	21	{
a90917c3 MD	22	struct lttng_event *event =
a90917c3 MD	23	container_of(p, struct lttng_event, u.kprobe.kp);
79150a49 JD	24	struct lttng_probe_ctx lttng_probe_ctx = {
79150a49 JD	25	.event = event,
ccecf3fb	26	.interruptible = !lttng_regs_irqs_disabled(regs),
79150a49	27	};
a90917c3	28	struct lttng_channel *chan = event->chan;
d6d808f3 MD	29	struct lib_ring_buffer_ctx ctx;
	30	int ret;
	31	unsigned long data = (unsigned long) p->addr;
	32
a8f2d0c7	33	if (unlikely(!READ_ONCE(chan->session->active)))
f17701fb	34	return 0;
a8f2d0c7	35	if (unlikely(!READ_ONCE(chan->enabled)))
e64957da	36	return 0;
a8f2d0c7	37	if (unlikely(!READ_ONCE(event->enabled)))
e64957da MD	38	return 0;
e64957da MD	39
79150a49	40	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx, sizeof(data),
a90917c3	41	lttng_alignof(data), -1);
4e1f08f4	42	ret = chan->ops->event_reserve(&ctx, event->id);
d6d808f3	43	if (ret < 0)
f17701fb	44	return 0;
a90917c3	45	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data));
d6d808f3 MD	46	chan->ops->event_write(&ctx, &data, sizeof(data));
d6d808f3 MD	47	chan->ops->event_commit(&ctx);
f17701fb	48	return 0;
d6d808f3	49	}
f17701fb MD	50
	51	/*
	52	* Create event description
	53	*/
	54	static
a90917c3	55	int lttng_create_kprobe_event(const char name, struct lttng_event event)
f17701fb MD	56	{
f17701fb MD	57	struct lttng_event_field *field;
d3dbe23c	58	struct lttng_event_desc *desc;
f17701fb MD	59	int ret;
f17701fb MD	60
d3dbe23c MD	61	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
d3dbe23c MD	62	if (!desc)
f17701fb	63	return -ENOMEM;
d3dbe23c MD	64	desc->name = kstrdup(name, GFP_KERNEL);
d3dbe23c MD	65	if (!desc->name) {
f17701fb MD	66	ret = -ENOMEM;
	67	goto error_str;
	68	}
d3dbe23c MD	69	desc->nr_fields = 1;
d3dbe23c MD	70	desc->fields = field =
f17701fb	71	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
0d1a681e MD	72	if (!field) {
	73	ret = -ENOMEM;
	74	goto error_field;
	75	}
f17701fb MD	76	field->name = "ip";
f17701fb MD	77	field->type.atype = atype_integer;
ba1f5986	78	field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
a90917c3	79	field->type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
06254b0f	80	field->type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
f17701fb	81	field->type.u.basic.integer.reverse_byte_order = 0;
e0a7a7c4 MD	82	field->type.u.basic.integer.base = 16;
e0a7a7c4 MD	83	field->type.u.basic.integer.encoding = lttng_encode_none;
dc7f600a	84	desc->owner = THIS_MODULE;
d3dbe23c	85	event->desc = desc;
f17701fb MD	86
	87	return 0;
	88
0d1a681e MD	89	error_field:
0d1a681e MD	90	kfree(desc->name);
f17701fb	91	error_str:
d3dbe23c	92	kfree(desc);
f17701fb MD	93	return ret;
	94	}
	95
	96	int lttng_kprobes_register(const char *name,
	97	const char *symbol_name,
	98	uint64_t offset,
	99	uint64_t addr,
a90917c3	100	struct lttng_event *event)
f17701fb MD	101	{
	102	int ret;
	103
c37f2a9b MD	104	/* Kprobes expects a NULL symbol name if unused */
	105	if (symbol_name[0] == '\0')
	106	symbol_name = NULL;
	107
f17701fb MD	108	ret = lttng_create_kprobe_event(name, event);
	109	if (ret)
	110	goto error;
	111	memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
	112	event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
c37f2a9b MD	113	if (symbol_name) {
c37f2a9b MD	114	event->u.kprobe.symbol_name =
f8695253	115	kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
c37f2a9b MD	116	GFP_KERNEL);
	117	if (!event->u.kprobe.symbol_name) {
	118	ret = -ENOMEM;
	119	goto name_error;
	120	}
	121	memcpy(event->u.kprobe.symbol_name, symbol_name,
f8695253	122	LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
c37f2a9b MD	123	event->u.kprobe.kp.symbol_name =
c37f2a9b MD	124	event->u.kprobe.symbol_name;
f17701fb	125	}
f17701fb	126	event->u.kprobe.kp.offset = offset;
b2c4e8fb	127	event->u.kprobe.kp.addr = (void *) (unsigned long) addr;
16a9a591 MD	128
	129	/*
	130	* Ensure the memory we just allocated don't trigger page faults.
	131	* Well.. kprobes itself puts the page fault handler on the blacklist,
	132	* but we can never be too careful.
	133	*/
	134	wrapper_vmalloc_sync_all();
	135
f17701fb MD	136	ret = register_kprobe(&event->u.kprobe.kp);
	137	if (ret)
	138	goto register_error;
	139	return 0;
	140
	141	register_error:
	142	kfree(event->u.kprobe.symbol_name);
	143	name_error:
0d1a681e	144	kfree(event->desc->fields);
f17701fb MD	145	kfree(event->desc->name);
	146	kfree(event->desc);
	147	error:
	148	return ret;
	149	}
	150	EXPORT_SYMBOL_GPL(lttng_kprobes_register);
	151
a90917c3	152	void lttng_kprobes_unregister(struct lttng_event *event)
f17701fb MD	153	{
f17701fb MD	154	unregister_kprobe(&event->u.kprobe.kp);
edeb3137 MD	155	}
	156	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
	157
a90917c3	158	void lttng_kprobes_destroy_private(struct lttng_event *event)
edeb3137	159	{
f17701fb	160	kfree(event->u.kprobe.symbol_name);
0d1a681e	161	kfree(event->desc->fields);
f17701fb MD	162	kfree(event->desc->name);
	163	kfree(event->desc);
	164	}
edeb3137	165	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_private);
d6d808f3 MD	166
d6d808f3 MD	167	MODULE_LICENSE("GPL and additional rights");
1c124020 MJ	168	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1c124020 MJ	169	MODULE_DESCRIPTION("LTTng kprobes probes");
13ab8b0a MD	170	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	171	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	172	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	173	LTTNG_MODULES_EXTRAVERSION);