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

/*
 * probes/lttng-kretprobes.c
 *
 * LTTng kretprobes integration module.
 *
 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/slab.h>
#include <linux/kref.h>
#include "../lttng-events.h"
#include "../wrapper/ringbuffer/frontend_types.h"
#include "../wrapper/vmalloc.h"
#include "../lttng-tracer.h"

enum lttng_kretprobe_type {
	EVENT_ENTRY = 0,
	EVENT_RETURN = 1,
};

struct lttng_krp {
	struct kretprobe krp;
	struct lttng_event *event[2];	/* ENTRY and RETURN */
	struct kref kref_register;
	struct kref kref_alloc;
};

static
int _lttng_kretprobes_handler(struct kretprobe_instance *krpi,
			      struct pt_regs *regs,
			      enum lttng_kretprobe_type type)
{
	struct lttng_krp *lttng_krp =
		container_of(krpi->rp, struct lttng_krp, krp);
	struct lttng_event *event =
		lttng_krp->event[type];
	struct lttng_channel *chan = event->chan;
	struct lib_ring_buffer_ctx ctx;
	int ret;
	struct {
		unsigned long ip;
		unsigned long parent_ip;
	} payload;

	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;

	payload.ip = (unsigned long) krpi->rp->kp.addr;
	payload.parent_ip = (unsigned long) krpi->ret_addr;

	lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(payload),
				 lttng_alignof(payload), -1);
	ret = chan->ops->event_reserve(&ctx, event->id);
	if (ret < 0)
		return 0;
	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	chan->ops->event_commit(&ctx);
	return 0;
}

static
int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi,
				   struct pt_regs *regs)
{
	return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY);
}

static
int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi,
				    struct pt_regs *regs)
{
	return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN);
}

/*
 * Create event description
 */
static
int lttng_create_kprobe_event(const char *name, struct lttng_event *event,
			      enum lttng_kretprobe_type type)
{
	struct lttng_event_field *fields;
	struct lttng_event_desc *desc;
	int ret;
	char *alloc_name;
	size_t name_len;
	const char *suffix = NULL;

	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	if (!desc)
		return -ENOMEM;
	name_len = strlen(name);
	switch (type) {
	case EVENT_ENTRY:
		suffix = "_entry";
		break;
	case EVENT_RETURN:
		suffix = "_return";
		break;
	}
	name_len += strlen(suffix);
	alloc_name = kmalloc(name_len + 1, GFP_KERNEL);
	if (!alloc_name) {
		ret = -ENOMEM;
		goto error_str;
	}
	strcpy(alloc_name, name);
	strcat(alloc_name, suffix);
	desc->name = alloc_name;
	desc->nr_fields = 2;
	desc->fields = fields =
		kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
	if (!desc->fields) {
		ret = -ENOMEM;
		goto error_fields;
	}
	fields[0].name = "ip";
	fields[0].type.atype = atype_integer;
	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	fields[0].type.u.basic.integer.reverse_byte_order = 0;
	fields[0].type.u.basic.integer.base = 16;
	fields[0].type.u.basic.integer.encoding = lttng_encode_none;

	fields[1].name = "parent_ip";
	fields[1].type.atype = atype_integer;
	fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	fields[1].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	fields[1].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	fields[1].type.u.basic.integer.reverse_byte_order = 0;
	fields[1].type.u.basic.integer.base = 16;
	fields[1].type.u.basic.integer.encoding = lttng_encode_none;

	desc->owner = THIS_MODULE;
	event->desc = desc;

	return 0;

error_fields:
	kfree(desc->name);
error_str:
	kfree(desc);
	return ret;
}

int lttng_kretprobes_register(const char *name,
			   const char *symbol_name,
			   uint64_t offset,
			   uint64_t addr,
			   struct lttng_event *event_entry,
			   struct lttng_event *event_return)
{
	int ret;
	struct lttng_krp *lttng_krp;

	/* Kprobes expects a NULL symbol name if unused */
	if (symbol_name[0] == '\0')
		symbol_name = NULL;

	ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY);
	if (ret)
		goto error;
	ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN);
	if (ret)
		goto event_return_error;
	lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL);
	if (!lttng_krp)
		goto krp_error;
	lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry;
	lttng_krp->krp.handler = lttng_kretprobes_handler_return;
	if (symbol_name) {
		char *alloc_symbol;

		alloc_symbol = kstrdup(symbol_name, GFP_KERNEL);
		if (!alloc_symbol) {
			ret = -ENOMEM;
			goto name_error;
		}
		lttng_krp->krp.kp.symbol_name =
			alloc_symbol;
		event_entry->u.kretprobe.symbol_name =
			alloc_symbol;
		event_return->u.kretprobe.symbol_name =
			alloc_symbol;
	}
	lttng_krp->krp.kp.offset = offset;
	lttng_krp->krp.kp.addr = (void *) (unsigned long) addr;

	/* Allow probe handler to find event structures */
	lttng_krp->event[EVENT_ENTRY] = event_entry;
	lttng_krp->event[EVENT_RETURN] = event_return;
	event_entry->u.kretprobe.lttng_krp = lttng_krp;
	event_return->u.kretprobe.lttng_krp = lttng_krp;

	/*
	 * Both events must be unregistered before the kretprobe is
	 * unregistered. Same for memory allocation.
	 */
	kref_init(&lttng_krp->kref_alloc);
	kref_get(&lttng_krp->kref_alloc);	/* inc refcount to 2 */
	kref_init(&lttng_krp->kref_register);
	kref_get(&lttng_krp->kref_register);	/* inc refcount to 2 */

	/*
	 * 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_kretprobe(&lttng_krp->krp);
	if (ret)
		goto register_error;
	return 0;

register_error:
	kfree(lttng_krp->krp.kp.symbol_name);
name_error:
	kfree(lttng_krp);
krp_error:
	kfree(event_return->desc->fields);
	kfree(event_return->desc->name);
	kfree(event_return->desc);
event_return_error:
	kfree(event_entry->desc->fields);
	kfree(event_entry->desc->name);
	kfree(event_entry->desc);
error:
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_kretprobes_register);

static
void _lttng_kretprobes_unregister_release(struct kref *kref)
{
	struct lttng_krp *lttng_krp =
		container_of(kref, struct lttng_krp, kref_register);
	unregister_kretprobe(&lttng_krp->krp);
}

void lttng_kretprobes_unregister(struct lttng_event *event)
{
	kref_put(&event->u.kretprobe.lttng_krp->kref_register,
		_lttng_kretprobes_unregister_release);
}
EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister);

static
void _lttng_kretprobes_release(struct kref *kref)
{
	struct lttng_krp *lttng_krp =
		container_of(kref, struct lttng_krp, kref_alloc);
	kfree(lttng_krp->krp.kp.symbol_name);
}

void lttng_kretprobes_destroy_private(struct lttng_event *event)
{
	kfree(event->desc->fields);
	kfree(event->desc->name);
	kfree(event->desc);
	kref_put(&event->u.kretprobe.lttng_krp->kref_alloc,
		_lttng_kretprobes_release);
}
EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private);

int lttng_kretprobes_event_enable_state(struct lttng_event *event,
		int enable)
{
	struct lttng_event *event_return;
	struct lttng_krp *lttng_krp;

	if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) {
		return -EINVAL;
	}
	if (event->enabled == enable) {
		return -EBUSY;
	}
	lttng_krp = event->u.kretprobe.lttng_krp;
	event_return = lttng_krp->event[EVENT_RETURN];
	ACCESS_ONCE(event->enabled) = enable;
	ACCESS_ONCE(event_return->enabled) = enable;
	return 0;
}
EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state);

MODULE_LICENSE("GPL and additional rights");
MODULE_AUTHOR("Mathieu Desnoyers");
MODULE_DESCRIPTION("Linux Trace Toolkit Kretprobes Support");
MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	LTTNG_MODULES_EXTRAVERSION);
Commit	Line	Data
	1	/*
	2	* probes/lttng-kretprobes.c
	3	*
	4	* LTTng kretprobes integration module.
	5	*
	6	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	7	*
	8	* This library is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU Lesser General Public
	10	* License as published by the Free Software Foundation; only
	11	* version 2.1 of the License.
	12	*
	13	* This library is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	16	* Lesser General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU Lesser General Public
	19	* License along with this library; if not, write to the Free Software
	20	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	21	*/
	22
	23	#include <linux/module.h>
	24	#include <linux/kprobes.h>
	25	#include <linux/slab.h>
	26	#include <linux/kref.h>
	27	#include "../lttng-events.h"
	28	#include "../wrapper/ringbuffer/frontend_types.h"
	29	#include "../wrapper/vmalloc.h"
	30	#include "../lttng-tracer.h"
	31
	32	enum lttng_kretprobe_type {
	33	EVENT_ENTRY = 0,
	34	EVENT_RETURN = 1,
	35	};
	36
	37	struct lttng_krp {
	38	struct kretprobe krp;
	39	struct lttng_event event[2]; / ENTRY and RETURN */
	40	struct kref kref_register;
	41	struct kref kref_alloc;
	42	};
	43
	44	static
	45	int _lttng_kretprobes_handler(struct kretprobe_instance *krpi,
	46	struct pt_regs *regs,
	47	enum lttng_kretprobe_type type)
	48	{
	49	struct lttng_krp *lttng_krp =
	50	container_of(krpi->rp, struct lttng_krp, krp);
	51	struct lttng_event *event =
	52	lttng_krp->event[type];
	53	struct lttng_channel *chan = event->chan;
	54	struct lib_ring_buffer_ctx ctx;
	55	int ret;
	56	struct {
	57	unsigned long ip;
	58	unsigned long parent_ip;
	59	} payload;
	60
	61	if (unlikely(!ACCESS_ONCE(chan->session->active)))
	62	return 0;
	63	if (unlikely(!ACCESS_ONCE(chan->enabled)))
	64	return 0;
	65	if (unlikely(!ACCESS_ONCE(event->enabled)))
	66	return 0;
	67
	68	payload.ip = (unsigned long) krpi->rp->kp.addr;
	69	payload.parent_ip = (unsigned long) krpi->ret_addr;
	70
	71	lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(payload),
	72	lttng_alignof(payload), -1);
	73	ret = chan->ops->event_reserve(&ctx, event->id);
	74	if (ret < 0)
	75	return 0;
	76	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	77	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	78	chan->ops->event_commit(&ctx);
	79	return 0;
	80	}
	81
	82	static
	83	int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi,
	84	struct pt_regs *regs)
	85	{
	86	return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY);
	87	}
	88
	89	static
	90	int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi,
	91	struct pt_regs *regs)
	92	{
	93	return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN);
	94	}
	95
	96	/*
	97	* Create event description
	98	*/
	99	static
	100	int lttng_create_kprobe_event(const char name, struct lttng_event event,
	101	enum lttng_kretprobe_type type)
	102	{
	103	struct lttng_event_field *fields;
	104	struct lttng_event_desc *desc;
	105	int ret;
	106	char *alloc_name;
	107	size_t name_len;
	108	const char *suffix = NULL;
	109
	110	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	111	if (!desc)
	112	return -ENOMEM;
	113	name_len = strlen(name);
	114	switch (type) {
	115	case EVENT_ENTRY:
	116	suffix = "_entry";
	117	break;
	118	case EVENT_RETURN:
	119	suffix = "_return";
	120	break;
	121	}
	122	name_len += strlen(suffix);
	123	alloc_name = kmalloc(name_len + 1, GFP_KERNEL);
	124	if (!alloc_name) {
	125	ret = -ENOMEM;
	126	goto error_str;
	127	}
	128	strcpy(alloc_name, name);
	129	strcat(alloc_name, suffix);
	130	desc->name = alloc_name;
	131	desc->nr_fields = 2;
	132	desc->fields = fields =
	133	kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
	134	if (!desc->fields) {
	135	ret = -ENOMEM;
	136	goto error_fields;
	137	}
	138	fields[0].name = "ip";
	139	fields[0].type.atype = atype_integer;
	140	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	141	fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	142	fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	143	fields[0].type.u.basic.integer.reverse_byte_order = 0;
	144	fields[0].type.u.basic.integer.base = 16;
	145	fields[0].type.u.basic.integer.encoding = lttng_encode_none;
	146
	147	fields[1].name = "parent_ip";
	148	fields[1].type.atype = atype_integer;
	149	fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	150	fields[1].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	151	fields[1].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	152	fields[1].type.u.basic.integer.reverse_byte_order = 0;
	153	fields[1].type.u.basic.integer.base = 16;
	154	fields[1].type.u.basic.integer.encoding = lttng_encode_none;
	155
	156	desc->owner = THIS_MODULE;
	157	event->desc = desc;
	158
	159	return 0;
	160
	161	error_fields:
	162	kfree(desc->name);
	163	error_str:
	164	kfree(desc);
	165	return ret;
	166	}
	167
	168	int lttng_kretprobes_register(const char *name,
	169	const char *symbol_name,
	170	uint64_t offset,
	171	uint64_t addr,
	172	struct lttng_event *event_entry,
	173	struct lttng_event *event_return)
	174	{
	175	int ret;
	176	struct lttng_krp *lttng_krp;
	177
	178	/* Kprobes expects a NULL symbol name if unused */
	179	if (symbol_name[0] == '\0')
	180	symbol_name = NULL;
	181
	182	ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY);
	183	if (ret)
	184	goto error;
	185	ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN);
	186	if (ret)
	187	goto event_return_error;
	188	lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL);
	189	if (!lttng_krp)
	190	goto krp_error;
	191	lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry;
	192	lttng_krp->krp.handler = lttng_kretprobes_handler_return;
	193	if (symbol_name) {
	194	char *alloc_symbol;
	195
	196	alloc_symbol = kstrdup(symbol_name, GFP_KERNEL);
	197	if (!alloc_symbol) {
	198	ret = -ENOMEM;
	199	goto name_error;
	200	}
	201	lttng_krp->krp.kp.symbol_name =
	202	alloc_symbol;
	203	event_entry->u.kretprobe.symbol_name =
	204	alloc_symbol;
	205	event_return->u.kretprobe.symbol_name =
	206	alloc_symbol;
	207	}
	208	lttng_krp->krp.kp.offset = offset;
	209	lttng_krp->krp.kp.addr = (void *) (unsigned long) addr;
	210
	211	/* Allow probe handler to find event structures */
	212	lttng_krp->event[EVENT_ENTRY] = event_entry;
	213	lttng_krp->event[EVENT_RETURN] = event_return;
	214	event_entry->u.kretprobe.lttng_krp = lttng_krp;
	215	event_return->u.kretprobe.lttng_krp = lttng_krp;
	216
	217	/*
	218	* Both events must be unregistered before the kretprobe is
	219	* unregistered. Same for memory allocation.
	220	*/
	221	kref_init(&lttng_krp->kref_alloc);
	222	kref_get(&lttng_krp->kref_alloc); /* inc refcount to 2 */
	223	kref_init(&lttng_krp->kref_register);
	224	kref_get(&lttng_krp->kref_register); /* inc refcount to 2 */
	225
	226	/*
	227	* Ensure the memory we just allocated don't trigger page faults.
	228	* Well.. kprobes itself puts the page fault handler on the blacklist,
	229	* but we can never be too careful.
	230	*/
	231	wrapper_vmalloc_sync_all();
	232
	233	ret = register_kretprobe(&lttng_krp->krp);
	234	if (ret)
	235	goto register_error;
	236	return 0;
	237
	238	register_error:
	239	kfree(lttng_krp->krp.kp.symbol_name);
	240	name_error:
	241	kfree(lttng_krp);
	242	krp_error:
	243	kfree(event_return->desc->fields);
	244	kfree(event_return->desc->name);
	245	kfree(event_return->desc);
	246	event_return_error:
	247	kfree(event_entry->desc->fields);
	248	kfree(event_entry->desc->name);
	249	kfree(event_entry->desc);
	250	error:
	251	return ret;
	252	}
	253	EXPORT_SYMBOL_GPL(lttng_kretprobes_register);
	254
	255	static
	256	void _lttng_kretprobes_unregister_release(struct kref *kref)
	257	{
	258	struct lttng_krp *lttng_krp =
	259	container_of(kref, struct lttng_krp, kref_register);
	260	unregister_kretprobe(&lttng_krp->krp);
	261	}
	262
	263	void lttng_kretprobes_unregister(struct lttng_event *event)
	264	{
	265	kref_put(&event->u.kretprobe.lttng_krp->kref_register,
	266	_lttng_kretprobes_unregister_release);
	267	}
	268	EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister);
	269
	270	static
	271	void _lttng_kretprobes_release(struct kref *kref)
	272	{
	273	struct lttng_krp *lttng_krp =
	274	container_of(kref, struct lttng_krp, kref_alloc);
	275	kfree(lttng_krp->krp.kp.symbol_name);
	276	}
	277
	278	void lttng_kretprobes_destroy_private(struct lttng_event *event)
	279	{
	280	kfree(event->desc->fields);
	281	kfree(event->desc->name);
	282	kfree(event->desc);
	283	kref_put(&event->u.kretprobe.lttng_krp->kref_alloc,
	284	_lttng_kretprobes_release);
	285	}
	286	EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private);
	287
	288	int lttng_kretprobes_event_enable_state(struct lttng_event *event,
	289	int enable)
	290	{
	291	struct lttng_event *event_return;
	292	struct lttng_krp *lttng_krp;
	293
	294	if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) {
	295	return -EINVAL;
	296	}
	297	if (event->enabled == enable) {
	298	return -EBUSY;
	299	}
	300	lttng_krp = event->u.kretprobe.lttng_krp;
	301	event_return = lttng_krp->event[EVENT_RETURN];
	302	ACCESS_ONCE(event->enabled) = enable;
	303	ACCESS_ONCE(event_return->enabled) = enable;
	304	return 0;
	305	}
	306	EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state);
	307
	308	MODULE_LICENSE("GPL and additional rights");
	309	MODULE_AUTHOR("Mathieu Desnoyers");
	310	MODULE_DESCRIPTION("Linux Trace Toolkit Kretprobes Support");
	311	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	312	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	313	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	314	LTTNG_MODULES_EXTRAVERSION);