[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 (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),
				 ltt_alignof(data), -1);
	ret = chan->ops->event_reserve(&ctx, event->id);
	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);
	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 = ltt_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 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->fields);
	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);
}
EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);

void lttng_kprobes_destroy_private(struct ltt_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
	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>
	12	#include <linux/slab.h>
	13	#include "../ltt-events.h"
	14	#include "../wrapper/ringbuffer/frontend_types.h"
	15	#include "../wrapper/vmalloc.h"
	16	#include "../ltt-tracer.h"
	17
	18	static
	19	int lttng_kprobes_handler_pre(struct kprobe p, struct pt_regs regs)
	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 (unlikely(!ACCESS_ONCE(chan->session->active)))
	29	return 0;
	30	if (unlikely(!ACCESS_ONCE(chan->enabled)))
	31	return 0;
	32	if (unlikely(!ACCESS_ONCE(event->enabled)))
	33	return 0;
	34
	35	lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(data),
	36	ltt_alignof(data), -1);
	37	ret = chan->ops->event_reserve(&ctx, event->id);
	38	if (ret < 0)
	39	return 0;
	40	lib_ring_buffer_align_ctx(&ctx, ltt_alignof(data));
	41	chan->ops->event_write(&ctx, &data, sizeof(data));
	42	chan->ops->event_commit(&ctx);
	43	return 0;
	44	}
	45
	46	/*
	47	* Create event description
	48	*/
	49	static
	50	int lttng_create_kprobe_event(const char name, struct ltt_event event)
	51	{
	52	struct lttng_event_field *field;
	53	struct lttng_event_desc *desc;
	54	int ret;
	55
	56	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	57	if (!desc)
	58	return -ENOMEM;
	59	desc->name = kstrdup(name, GFP_KERNEL);
	60	if (!desc->name) {
	61	ret = -ENOMEM;
	62	goto error_str;
	63	}
	64	desc->nr_fields = 1;
	65	desc->fields = field =
	66	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
	67	if (!field) {
	68	ret = -ENOMEM;
	69	goto error_field;
	70	}
	71	field->name = "ip";
	72	field->type.atype = atype_integer;
	73	field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	74	field->type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
	75	field->type.u.basic.integer.signedness = is_signed_type(unsigned long);
	76	field->type.u.basic.integer.reverse_byte_order = 0;
	77	field->type.u.basic.integer.base = 16;
	78	field->type.u.basic.integer.encoding = lttng_encode_none;
	79	desc->owner = THIS_MODULE;
	80	event->desc = desc;
	81
	82	return 0;
	83
	84	error_field:
	85	kfree(desc->name);
	86	error_str:
	87	kfree(desc);
	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,
	95	struct ltt_event *event)
	96	{
	97	int ret;
	98
	99	ret = lttng_create_kprobe_event(name, event);
	100	if (ret)
	101	goto error;
	102	memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
	103	event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
	104	event->u.kprobe.symbol_name =
	105	kzalloc(LTTNG_SYM_NAME_LEN * sizeof(char),
	106	GFP_KERNEL);
	107	if (!event->u.kprobe.symbol_name) {
	108	ret = -ENOMEM;
	109	goto name_error;
	110	}
	111	memcpy(event->u.kprobe.symbol_name, symbol_name,
	112	LTTNG_SYM_NAME_LEN * sizeof(char));
	113	event->u.kprobe.kp.symbol_name =
	114	event->u.kprobe.symbol_name;
	115	event->u.kprobe.kp.offset = offset;
	116	event->u.kprobe.kp.addr = (void *) addr;
	117
	118	/*
	119	* Ensure the memory we just allocated don't trigger page faults.
	120	* Well.. kprobes itself puts the page fault handler on the blacklist,
	121	* but we can never be too careful.
	122	*/
	123	wrapper_vmalloc_sync_all();
	124
	125	ret = register_kprobe(&event->u.kprobe.kp);
	126	if (ret)
	127	goto register_error;
	128	return 0;
	129
	130	register_error:
	131	kfree(event->u.kprobe.symbol_name);
	132	name_error:
	133	kfree(event->desc->fields);
	134	kfree(event->desc->name);
	135	kfree(event->desc);
	136	error:
	137	return ret;
	138	}
	139	EXPORT_SYMBOL_GPL(lttng_kprobes_register);
	140
	141	void lttng_kprobes_unregister(struct ltt_event *event)
	142	{
	143	unregister_kprobe(&event->u.kprobe.kp);
	144	}
	145	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
	146
	147	void lttng_kprobes_destroy_private(struct ltt_event *event)
	148	{
	149	kfree(event->u.kprobe.symbol_name);
	150	kfree(event->desc->fields);
	151	kfree(event->desc->name);
	152	kfree(event->desc);
	153	}
	154	EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_private);
	155
	156	MODULE_LICENSE("GPL and additional rights");
	157	MODULE_AUTHOR("Mathieu Desnoyers");
	158	MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support");