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

/*
 * (C) Copyright	2009-2011 -
 * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * LTTng kprobes integration module.
 *
 * Dual LGPL v2.1/GPL v2 license.
 */

#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 "../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_channel *chan = event->chan;
	struct lib_ring_buffer_ctx ctx;
	int ret;
	unsigned long data = (unsigned long) p->addr;

	if (unlikely(!ACCESS_ONCE(chan->session->active)))
		return 0;
	if (unlikely(!ACCESS_ONCE(chan->enabled)))
		return 0;
	if (unlikely(!ACCESS_ONCE(event->enabled)))
		return 0;

	lib_ring_buffer_ctx_init(&ctx, chan->chan, event, 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 = 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_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_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");
MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support");
Commit	Line	Data
d6d808f3 MD	1	/*
	2	* (C) Copyright 2009-2011 -
	3	* Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	4	*
	5	* LTTng kprobes integration module.
	6	*
	7	* Dual LGPL v2.1/GPL v2 license.
	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/kprobes.h>
f17701fb	12	#include <linux/slab.h>
a90917c3	13	#include "../lttng-events.h"
d6d808f3	14	#include "../wrapper/ringbuffer/frontend_types.h"
16a9a591	15	#include "../wrapper/vmalloc.h"
a90917c3	16	#include "../lttng-tracer.h"
d6d808f3	17
f17701fb MD	18	static
f17701fb MD	19	int lttng_kprobes_handler_pre(struct kprobe p, struct pt_regs regs)
d6d808f3	20	{
a90917c3 MD	21	struct lttng_event *event =
	22	container_of(p, struct lttng_event, u.kprobe.kp);
	23	struct lttng_channel *chan = event->chan;
d6d808f3 MD	24	struct lib_ring_buffer_ctx ctx;
	25	int ret;
	26	unsigned long data = (unsigned long) p->addr;
	27
e64957da	28	if (unlikely(!ACCESS_ONCE(chan->session->active)))
f17701fb	29	return 0;
e64957da MD	30	if (unlikely(!ACCESS_ONCE(chan->enabled)))
	31	return 0;
	32	if (unlikely(!ACCESS_ONCE(event->enabled)))
	33	return 0;
	34
f1676205	35	lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(data),
a90917c3	36	lttng_alignof(data), -1);
4e1f08f4	37	ret = chan->ops->event_reserve(&ctx, event->id);
d6d808f3	38	if (ret < 0)
f17701fb	39	return 0;
a90917c3	40	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(data));
d6d808f3 MD	41	chan->ops->event_write(&ctx, &data, sizeof(data));
d6d808f3 MD	42	chan->ops->event_commit(&ctx);
f17701fb	43	return 0;
d6d808f3	44	}
f17701fb MD	45
	46	/*
	47	* Create event description
	48	*/
	49	static
a90917c3	50	int lttng_create_kprobe_event(const char name, struct lttng_event event)
f17701fb MD	51	{
f17701fb MD	52	struct lttng_event_field *field;
d3dbe23c	53	struct lttng_event_desc *desc;
f17701fb MD	54	int ret;
f17701fb MD	55
d3dbe23c MD	56	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
d3dbe23c MD	57	if (!desc)
f17701fb	58	return -ENOMEM;
d3dbe23c MD	59	desc->name = kstrdup(name, GFP_KERNEL);
d3dbe23c MD	60	if (!desc->name) {
f17701fb MD	61	ret = -ENOMEM;
	62	goto error_str;
	63	}
d3dbe23c MD	64	desc->nr_fields = 1;
d3dbe23c MD	65	desc->fields = field =
f17701fb	66	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
0d1a681e MD	67	if (!field) {
	68	ret = -ENOMEM;
	69	goto error_field;
	70	}
f17701fb MD	71	field->name = "ip";
f17701fb MD	72	field->type.atype = atype_integer;
ba1f5986	73	field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
a90917c3	74	field->type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
9e7e4892	75	field->type.u.basic.integer.signedness = is_signed_type(unsigned long);
f17701fb	76	field->type.u.basic.integer.reverse_byte_order = 0;
e0a7a7c4 MD	77	field->type.u.basic.integer.base = 16;
e0a7a7c4 MD	78	field->type.u.basic.integer.encoding = lttng_encode_none;
dc7f600a	79	desc->owner = THIS_MODULE;
d3dbe23c	80	event->desc = desc;
f17701fb MD	81
	82	return 0;
	83
0d1a681e MD	84	error_field:
0d1a681e MD	85	kfree(desc->name);
f17701fb	86	error_str:
d3dbe23c	87	kfree(desc);
f17701fb MD	88	return ret;
	89	}
	90
	91	int lttng_kprobes_register(const char *name,
	92	const char *symbol_name,
	93	uint64_t offset,
	94	uint64_t addr,
a90917c3	95	struct lttng_event *event)
f17701fb MD	96	{
	97	int ret;
	98
c37f2a9b MD	99	/* Kprobes expects a NULL symbol name if unused */
	100	if (symbol_name[0] == '\0')
	101	symbol_name = NULL;
	102
f17701fb MD	103	ret = lttng_create_kprobe_event(name, event);
	104	if (ret)
	105	goto error;
	106	memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
	107	event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
c37f2a9b MD	108	if (symbol_name) {
	109	event->u.kprobe.symbol_name =
	110	kzalloc(LTTNG_SYM_NAME_LEN * sizeof(char),
	111	GFP_KERNEL);
	112	if (!event->u.kprobe.symbol_name) {
	113	ret = -ENOMEM;
	114	goto name_error;
	115	}
	116	memcpy(event->u.kprobe.symbol_name, symbol_name,
	117	LTTNG_SYM_NAME_LEN * sizeof(char));
	118	event->u.kprobe.kp.symbol_name =
	119	event->u.kprobe.symbol_name;
f17701fb	120	}
f17701fb	121	event->u.kprobe.kp.offset = offset;
b2c4e8fb	122	event->u.kprobe.kp.addr = (void *) (unsigned long) addr;
16a9a591 MD	123
	124	/*
	125	* Ensure the memory we just allocated don't trigger page faults.
	126	* Well.. kprobes itself puts the page fault handler on the blacklist,
	127	* but we can never be too careful.
	128	*/
	129	wrapper_vmalloc_sync_all();
	130
f17701fb MD	131	ret = register_kprobe(&event->u.kprobe.kp);
	132	if (ret)
	133	goto register_error;
	134	return 0;
	135
	136	register_error:
	137	kfree(event->u.kprobe.symbol_name);
	138	name_error:
0d1a681e	139	kfree(event->desc->fields);
f17701fb MD	140	kfree(event->desc->name);
	141	kfree(event->desc);
	142	error:
	143	return ret;
	144	}
	145	EXPORT_SYMBOL_GPL(lttng_kprobes_register);
	146
a90917c3	147	void lttng_kprobes_unregister(struct lttng_event *event)
f17701fb MD	148	{
f17701fb MD	149	unregister_kprobe(&event->u.kprobe.kp);
edeb3137 MD	150	}
	151	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
	152
a90917c3	153	void lttng_kprobes_destroy_private(struct lttng_event *event)
edeb3137	154	{
f17701fb	155	kfree(event->u.kprobe.symbol_name);
0d1a681e	156	kfree(event->desc->fields);
f17701fb MD	157	kfree(event->desc->name);
	158	kfree(event->desc);
	159	}
edeb3137	160	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_private);
d6d808f3 MD	161
	162	MODULE_LICENSE("GPL and additional rights");
	163	MODULE_AUTHOR("Mathieu Desnoyers");
	164	MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support");