[lttng-modules.git] / 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_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.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;
}

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_mappings();

	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
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>
156a3977	13	#include <lttng-events.h>
24591303	14	#include <ringbuffer/frontend_types.h>
156a3977 MD	15	#include <wrapper/vmalloc.h>
	16	#include <wrapper/irqflags.h>
	17	#include <lttng-tracer.h>
caa068b5	18	#include <blacklist/kprobes.h>
d6d808f3	19
f17701fb MD	20	static
f17701fb MD	21	int lttng_kprobes_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
a8f2d0c7	34	if (unlikely(!READ_ONCE(chan->session->active)))
f17701fb	35	return 0;
a8f2d0c7	36	if (unlikely(!READ_ONCE(chan->enabled)))
e64957da	37	return 0;
a8f2d0c7	38	if (unlikely(!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 MD	51
	52	/*
	53	* Create event description
	54	*/
	55	static
a90917c3	56	int lttng_create_kprobe_event(const char name, struct lttng_event event)
f17701fb MD	57	{
f17701fb MD	58	struct lttng_event_field *field;
d3dbe23c	59	struct lttng_event_desc *desc;
f17701fb MD	60	int ret;
f17701fb MD	61
d3dbe23c MD	62	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
d3dbe23c MD	63	if (!desc)
f17701fb	64	return -ENOMEM;
d3dbe23c MD	65	desc->name = kstrdup(name, GFP_KERNEL);
d3dbe23c MD	66	if (!desc->name) {
f17701fb MD	67	ret = -ENOMEM;
	68	goto error_str;
	69	}
d3dbe23c MD	70	desc->nr_fields = 1;
d3dbe23c MD	71	desc->fields = field =
f17701fb	72	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
0d1a681e MD	73	if (!field) {
	74	ret = -ENOMEM;
	75	goto error_field;
	76	}
f17701fb MD	77	field->name = "ip";
f17701fb MD	78	field->type.atype = atype_integer;
ceabb767 MD	79	field->type.u.integer.size = sizeof(unsigned long) * CHAR_BIT;
	80	field->type.u.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	81	field->type.u.integer.signedness = lttng_is_signed_type(unsigned long);
	82	field->type.u.integer.reverse_byte_order = 0;
	83	field->type.u.integer.base = 16;
	84	field->type.u.integer.encoding = lttng_encode_none;
dc7f600a	85	desc->owner = THIS_MODULE;
d3dbe23c	86	event->desc = desc;
f17701fb MD	87
	88	return 0;
	89
0d1a681e MD	90	error_field:
0d1a681e MD	91	kfree(desc->name);
f17701fb	92	error_str:
d3dbe23c	93	kfree(desc);
f17701fb MD	94	return ret;
	95	}
	96
	97	int lttng_kprobes_register(const char *name,
	98	const char *symbol_name,
	99	uint64_t offset,
	100	uint64_t addr,
a90917c3	101	struct lttng_event *event)
f17701fb MD	102	{
	103	int ret;
	104
c37f2a9b MD	105	/* Kprobes expects a NULL symbol name if unused */
	106	if (symbol_name[0] == '\0')
	107	symbol_name = NULL;
	108
f17701fb MD	109	ret = lttng_create_kprobe_event(name, event);
	110	if (ret)
	111	goto error;
	112	memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
	113	event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
c37f2a9b MD	114	if (symbol_name) {
c37f2a9b MD	115	event->u.kprobe.symbol_name =
f8695253	116	kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
c37f2a9b MD	117	GFP_KERNEL);
	118	if (!event->u.kprobe.symbol_name) {
	119	ret = -ENOMEM;
	120	goto name_error;
	121	}
	122	memcpy(event->u.kprobe.symbol_name, symbol_name,
f8695253	123	LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
c37f2a9b MD	124	event->u.kprobe.kp.symbol_name =
c37f2a9b MD	125	event->u.kprobe.symbol_name;
f17701fb	126	}
f17701fb	127	event->u.kprobe.kp.offset = offset;
b2c4e8fb	128	event->u.kprobe.kp.addr = (void *) (unsigned long) addr;
16a9a591 MD	129
	130	/*
	131	* Ensure the memory we just allocated don't trigger page faults.
	132	* Well.. kprobes itself puts the page fault handler on the blacklist,
	133	* but we can never be too careful.
	134	*/
263b6c88	135	wrapper_vmalloc_sync_mappings();
16a9a591	136
f17701fb MD	137	ret = register_kprobe(&event->u.kprobe.kp);
	138	if (ret)
	139	goto register_error;
	140	return 0;
	141
	142	register_error:
	143	kfree(event->u.kprobe.symbol_name);
	144	name_error:
0d1a681e	145	kfree(event->desc->fields);
f17701fb MD	146	kfree(event->desc->name);
	147	kfree(event->desc);
	148	error:
	149	return ret;
	150	}
	151	EXPORT_SYMBOL_GPL(lttng_kprobes_register);
	152
a90917c3	153	void lttng_kprobes_unregister(struct lttng_event *event)
f17701fb MD	154	{
f17701fb MD	155	unregister_kprobe(&event->u.kprobe.kp);
edeb3137 MD	156	}
	157	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
	158
a90917c3	159	void lttng_kprobes_destroy_private(struct lttng_event *event)
edeb3137	160	{
f17701fb	161	kfree(event->u.kprobe.symbol_name);
0d1a681e	162	kfree(event->desc->fields);
f17701fb MD	163	kfree(event->desc->name);
	164	kfree(event->desc);
	165	}
edeb3137	166	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_private);
d6d808f3 MD	167
d6d808f3 MD	168	MODULE_LICENSE("GPL and additional rights");
1c124020 MJ	169	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1c124020 MJ	170	MODULE_DESCRIPTION("LTTng kprobes probes");
13ab8b0a MD	171	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	172	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	173	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	174	LTTNG_MODULES_EXTRAVERSION);