[deliverable/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, 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 = 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;
	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);
	kfree(event->u.kprobe.symbol_name);
	kfree(event->desc->fields);
	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
	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 (!ACCESS_ONCE(chan->session->active))
	29	return 0;
	30	lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, sizeof(data),
	31	ltt_alignof(data), -1);
	32	ret = chan->ops->event_reserve(&ctx, event->id);
	33	if (ret < 0)
	34	return 0;
	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);
	38	return 0;
	39	}
	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;
	48	struct lttng_event_desc *desc;
	49	int ret;
	50
	51	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	52	if (!desc)
	53	return -ENOMEM;
	54	desc->name = kstrdup(name, GFP_KERNEL);
	55	if (!desc->name) {
	56	ret = -ENOMEM;
	57	goto error_str;
	58	}
	59	desc->nr_fields = 1;
	60	desc->fields = field =
	61	kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
	62	if (!field) {
	63	ret = -ENOMEM;
	64	goto error_field;
	65	}
	66	field->name = "ip";
	67	field->type.atype = atype_integer;
	68	field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	69	field->type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
	70	field->type.u.basic.integer.signedness = 0;
	71	field->type.u.basic.integer.reverse_byte_order = 0;
	72	field->type.u.basic.integer.base = 16;
	73	field->type.u.basic.integer.encoding = lttng_encode_none;
	74	desc->owner = THIS_MODULE;
	75	event->desc = desc;
	76
	77	return 0;
	78
	79	error_field:
	80	kfree(desc->name);
	81	error_str:
	82	kfree(desc);
	83	return ret;
	84	}
	85
	86	int lttng_kprobes_register(const char *name,
	87	const char *symbol_name,
	88	uint64_t offset,
	89	uint64_t addr,
	90	struct ltt_event *event)
	91	{
	92	int ret;
	93
	94	ret = lttng_create_kprobe_event(name, event);
	95	if (ret)
	96	goto error;
	97	memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
	98	event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
	99	event->u.kprobe.symbol_name =
	100	kzalloc(LTTNG_SYM_NAME_LEN * sizeof(char),
	101	GFP_KERNEL);
	102	if (!event->u.kprobe.symbol_name) {
	103	ret = -ENOMEM;
	104	goto name_error;
	105	}
	106	memcpy(event->u.kprobe.symbol_name, symbol_name,
	107	LTTNG_SYM_NAME_LEN * sizeof(char));
	108	event->u.kprobe.kp.symbol_name =
	109	event->u.kprobe.symbol_name;
	110	event->u.kprobe.kp.offset = offset;
	111	event->u.kprobe.kp.addr = (void *) addr;
	112
	113	/*
	114	* Ensure the memory we just allocated don't trigger page faults.
	115	* Well.. kprobes itself puts the page fault handler on the blacklist,
	116	* but we can never be too careful.
	117	*/
	118	wrapper_vmalloc_sync_all();
	119
	120	ret = register_kprobe(&event->u.kprobe.kp);
	121	if (ret)
	122	goto register_error;
	123	return 0;
	124
	125	register_error:
	126	kfree(event->u.kprobe.symbol_name);
	127	name_error:
	128	kfree(event->desc->fields);
	129	kfree(event->desc->name);
	130	kfree(event->desc);
	131	error:
	132	return ret;
	133	}
	134	EXPORT_SYMBOL_GPL(lttng_kprobes_register);
	135
	136	void lttng_kprobes_unregister(struct ltt_event *event)
	137	{
	138	unregister_kprobe(&event->u.kprobe.kp);
	139	kfree(event->u.kprobe.symbol_name);
	140	kfree(event->desc->fields);
	141	kfree(event->desc->name);
	142	kfree(event->desc);
	143	}
	144	EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
	145
	146	MODULE_LICENSE("GPL and additional rights");
	147	MODULE_AUTHOR("Mathieu Desnoyers");
	148	MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support");