[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 "../ltt-events.h"
#include "../wrapper/ringbuffer/frontend_types.h"
#include "../wrapper/vmalloc.h"
#include "../ltt-tracer.h"

static
int lttng_kprobes_handler_pre(struct kprobe *p, struct pt_regs *regs)
{
	struct ltt_event *event =
		container_of(p, struct ltt_event, u.kprobe.kp);
	struct ltt_channel *chan = event->chan;
	struct lib_ring_buffer_ctx ctx;
	int ret;
	unsigned long data = (unsigned long) p->addr;

	if (!ACCESS_ONCE(chan->session->active))
		return 0;
	lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, sizeof(data),
				 ltt_alignof(data), -1);
	ret = chan->ops->event_reserve(&ctx);
	if (ret < 0)
		return 0;
	lib_ring_buffer_align_ctx(&ctx, ltt_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 ltt_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);
	field->name = "ip";
	field->type.atype = atype_integer;
	field->type.u.basic.integer.size = sizeof(unsigned long);
	field->type.u.basic.integer.alignment = ltt_alignof(unsigned long);
	field->type.u.basic.integer.signedness = 0;
	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;
	event->desc = desc;

	return 0;

error_str:
	kfree(desc);
	return ret;
}

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

	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;
	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 *) 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->name);
	kfree(event->desc);
error:
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_kprobes_register);

void lttng_kprobes_unregister(struct ltt_event *event)
{
	unregister_kprobe(&event->u.kprobe.kp);
	kfree(event->u.kprobe.symbol_name);
	kfree(event->desc->name);
	kfree(event->desc);
}
EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);

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>
d6d808f3 MD	13	#include "../ltt-events.h"
d6d808f3 MD	14	#include "../wrapper/ringbuffer/frontend_types.h"
16a9a591	15	#include "../wrapper/vmalloc.h"
d6d808f3 MD	16	#include "../ltt-tracer.h"
d6d808f3 MD	17
f17701fb MD	18	static
f17701fb MD	19	int lttng_kprobes_handler_pre(struct kprobe p, struct pt_regs regs)
d6d808f3 MD	20	{
	21	struct ltt_event *event =
	22	container_of(p, struct ltt_event, u.kprobe.kp);
	23	struct ltt_channel *chan = event->chan;
	24	struct lib_ring_buffer_ctx ctx;
	25	int ret;
	26	unsigned long data = (unsigned long) p->addr;
	27
	28	if (!ACCESS_ONCE(chan->session->active))
f17701fb	29	return 0;
d6d808f3 MD	30	lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, sizeof(data),
	31	ltt_alignof(data), -1);
	32	ret = chan->ops->event_reserve(&ctx);
	33	if (ret < 0)
f17701fb	34	return 0;
d6d808f3 MD	35	lib_ring_buffer_align_ctx(&ctx, ltt_alignof(data));
	36	chan->ops->event_write(&ctx, &data, sizeof(data));
	37	chan->ops->event_commit(&ctx);
f17701fb	38	return 0;
d6d808f3	39	}
f17701fb MD	40
	41	/*
	42	* Create event description
	43	*/
	44	static
	45	int lttng_create_kprobe_event(const char name, struct ltt_event event)
	46	{
	47	struct lttng_event_field *field;
d3dbe23c	48	struct lttng_event_desc *desc;
f17701fb MD	49	int ret;
f17701fb MD	50
d3dbe23c MD	51	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
d3dbe23c MD	52	if (!desc)
f17701fb	53	return -ENOMEM;
d3dbe23c MD	54	desc->name = kstrdup(name, GFP_KERNEL);
d3dbe23c MD	55	if (!desc->name) {
f17701fb MD	56	ret = -ENOMEM;
	57	goto error_str;
	58	}
d3dbe23c MD	59	desc->nr_fields = 1;
d3dbe23c MD	60	desc->fields = field =
f17701fb MD	61	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
	62	field->name = "ip";
	63	field->type.atype = atype_integer;
	64	field->type.u.basic.integer.size = sizeof(unsigned long);
	65	field->type.u.basic.integer.alignment = ltt_alignof(unsigned long);
	66	field->type.u.basic.integer.signedness = 0;
	67	field->type.u.basic.integer.reverse_byte_order = 0;
e0a7a7c4 MD	68	field->type.u.basic.integer.base = 16;
e0a7a7c4 MD	69	field->type.u.basic.integer.encoding = lttng_encode_none;
d3dbe23c	70	event->desc = desc;
f17701fb MD	71
	72	return 0;
	73
	74	error_str:
d3dbe23c	75	kfree(desc);
f17701fb MD	76	return ret;
	77	}
	78
	79	int lttng_kprobes_register(const char *name,
	80	const char *symbol_name,
	81	uint64_t offset,
	82	uint64_t addr,
	83	struct ltt_event *event)
	84	{
	85	int ret;
	86
	87	ret = lttng_create_kprobe_event(name, event);
	88	if (ret)
	89	goto error;
	90	memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
	91	event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
	92	event->u.kprobe.symbol_name =
e0a7a7c4	93	kzalloc(LTTNG_SYM_NAME_LEN * sizeof(char),
f17701fb MD	94	GFP_KERNEL);
	95	if (!event->u.kprobe.symbol_name) {
	96	ret = -ENOMEM;
	97	goto name_error;
	98	}
	99	memcpy(event->u.kprobe.symbol_name, symbol_name,
e0a7a7c4	100	LTTNG_SYM_NAME_LEN * sizeof(char));
f17701fb MD	101	event->u.kprobe.kp.symbol_name =
	102	event->u.kprobe.symbol_name;
	103	event->u.kprobe.kp.offset = offset;
	104	event->u.kprobe.kp.addr = (void *) addr;
16a9a591 MD	105
	106	/*
	107	* Ensure the memory we just allocated don't trigger page faults.
	108	* Well.. kprobes itself puts the page fault handler on the blacklist,
	109	* but we can never be too careful.
	110	*/
	111	wrapper_vmalloc_sync_all();
	112
f17701fb MD	113	ret = register_kprobe(&event->u.kprobe.kp);
	114	if (ret)
	115	goto register_error;
	116	return 0;
	117
	118	register_error:
	119	kfree(event->u.kprobe.symbol_name);
	120	name_error:
	121	kfree(event->desc->name);
	122	kfree(event->desc);
	123	error:
	124	return ret;
	125	}
	126	EXPORT_SYMBOL_GPL(lttng_kprobes_register);
	127
	128	void lttng_kprobes_unregister(struct ltt_event *event)
	129	{
	130	unregister_kprobe(&event->u.kprobe.kp);
	131	kfree(event->u.kprobe.symbol_name);
	132	kfree(event->desc->name);
	133	kfree(event->desc);
	134	}
	135	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
d6d808f3 MD	136
	137	MODULE_LICENSE("GPL and additional rights");
	138	MODULE_AUTHOR("Mathieu Desnoyers");
	139	MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support");