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

/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
 *
 * probes/lttng-kretprobes.c
 *
 * LTTng kretprobes integration module.
 *
 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#include <linux/module.h>
#include <wrapper/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 <wrapper/irqflags.h>
#include <lttng-tracer.h>
#include <blacklist/kprobes.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(lttng_get_kretprobe(krpi), struct lttng_krp, krp);
	struct lttng_event *event =
		lttng_krp->event[type];
	struct lttng_probe_ctx lttng_probe_ctx = {
		.event = event,
		.interruptible = !lttng_regs_irqs_disabled(regs),
	};
	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(!LTTNG_READ_ONCE(chan->session->active)))
		return 0;
	if (unlikely(!LTTNG_READ_ONCE(chan->enabled)))
		return 0;
	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
		return 0;

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

	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx, 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, no overflow. */
	kref_init(&lttng_krp->kref_register);
	kref_get(&lttng_krp->kref_register);	/* inc refcount to 2, no overflow. */

	/*
	 * 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_mappings();

	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];
	WRITE_ONCE(event->enabled, enable);
	WRITE_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 <mathieu.desnoyers@efficios.com>");
MODULE_DESCRIPTION("LTTng kretprobes probes");
MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	LTTNG_MODULES_EXTRAVERSION);
Commit	Line	Data
9f36eaed MJ	1	/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
	2	*
	3	* probes/lttng-kretprobes.c
7371f44c MD	4	*
	5	* LTTng kretprobes integration module.
	6	*
886d51a3	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
7371f44c MD	8	*/
	9
	10	#include <linux/module.h>
9097b0c2	11	#include <wrapper/kprobes.h>
7371f44c MD	12	#include <linux/slab.h>
7371f44c MD	13	#include <linux/kref.h>
156a3977 MD	14	#include <lttng-events.h>
	15	#include <wrapper/ringbuffer/frontend_types.h>
	16	#include <wrapper/vmalloc.h>
	17	#include <wrapper/irqflags.h>
	18	#include <lttng-tracer.h>
caa068b5	19	#include <blacklist/kprobes.h>
7371f44c MD	20
	21	enum lttng_kretprobe_type {
	22	EVENT_ENTRY = 0,
	23	EVENT_RETURN = 1,
	24	};
	25
	26	struct lttng_krp {
	27	struct kretprobe krp;
a90917c3	28	struct lttng_event event[2]; / ENTRY and RETURN */
7371f44c MD	29	struct kref kref_register;
	30	struct kref kref_alloc;
	31	};
	32
	33	static
	34	int _lttng_kretprobes_handler(struct kretprobe_instance *krpi,
	35	struct pt_regs *regs,
	36	enum lttng_kretprobe_type type)
	37	{
	38	struct lttng_krp *lttng_krp =
9097b0c2	39	container_of(lttng_get_kretprobe(krpi), struct lttng_krp, krp);
a90917c3	40	struct lttng_event *event =
7371f44c	41	lttng_krp->event[type];
79150a49 JD	42	struct lttng_probe_ctx lttng_probe_ctx = {
79150a49 JD	43	.event = event,
ccecf3fb	44	.interruptible = !lttng_regs_irqs_disabled(regs),
79150a49	45	};
a90917c3	46	struct lttng_channel *chan = event->chan;
7371f44c MD	47	struct lib_ring_buffer_ctx ctx;
	48	int ret;
	49	struct {
	50	unsigned long ip;
	51	unsigned long parent_ip;
	52	} payload;
	53
57ccbfa6	54	if (unlikely(!LTTNG_READ_ONCE(chan->session->active)))
7371f44c	55	return 0;
57ccbfa6	56	if (unlikely(!LTTNG_READ_ONCE(chan->enabled)))
7371f44c	57	return 0;
57ccbfa6	58	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
7371f44c MD	59	return 0;
7371f44c MD	60
9097b0c2	61	payload.ip = (unsigned long) lttng_get_kretprobe(krpi)->kp.addr;
7371f44c MD	62	payload.parent_ip = (unsigned long) krpi->ret_addr;
7371f44c MD	63
79150a49	64	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx, sizeof(payload),
a90917c3	65	lttng_alignof(payload), -1);
7371f44c MD	66	ret = chan->ops->event_reserve(&ctx, event->id);
	67	if (ret < 0)
	68	return 0;
a90917c3	69	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
7371f44c MD	70	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	71	chan->ops->event_commit(&ctx);
	72	return 0;
	73	}
	74
	75	static
	76	int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi,
	77	struct pt_regs *regs)
	78	{
	79	return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY);
	80	}
	81
	82	static
	83	int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi,
	84	struct pt_regs *regs)
	85	{
	86	return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN);
	87	}
	88
	89	/*
	90	* Create event description
	91	*/
	92	static
a90917c3	93	int lttng_create_kprobe_event(const char name, struct lttng_event event,
7371f44c MD	94	enum lttng_kretprobe_type type)
	95	{
	96	struct lttng_event_field *fields;
	97	struct lttng_event_desc *desc;
	98	int ret;
	99	char *alloc_name;
	100	size_t name_len;
	101	const char *suffix = NULL;
	102
	103	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	104	if (!desc)
	105	return -ENOMEM;
	106	name_len = strlen(name);
	107	switch (type) {
	108	case EVENT_ENTRY:
	109	suffix = "_entry";
	110	break;
	111	case EVENT_RETURN:
	112	suffix = "_return";
	113	break;
	114	}
	115	name_len += strlen(suffix);
	116	alloc_name = kmalloc(name_len + 1, GFP_KERNEL);
	117	if (!alloc_name) {
	118	ret = -ENOMEM;
	119	goto error_str;
	120	}
	121	strcpy(alloc_name, name);
	122	strcat(alloc_name, suffix);
	123	desc->name = alloc_name;
	124	desc->nr_fields = 2;
	125	desc->fields = fields =
	126	kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
	127	if (!desc->fields) {
	128	ret = -ENOMEM;
	129	goto error_fields;
	130	}
	131	fields[0].name = "ip";
	132	fields[0].type.atype = atype_integer;
	133	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
a90917c3	134	fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
06254b0f	135	fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
7371f44c MD	136	fields[0].type.u.basic.integer.reverse_byte_order = 0;
	137	fields[0].type.u.basic.integer.base = 16;
	138	fields[0].type.u.basic.integer.encoding = lttng_encode_none;
	139
	140	fields[1].name = "parent_ip";
	141	fields[1].type.atype = atype_integer;
	142	fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
a90917c3	143	fields[1].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
06254b0f	144	fields[1].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
7371f44c MD	145	fields[1].type.u.basic.integer.reverse_byte_order = 0;
	146	fields[1].type.u.basic.integer.base = 16;
	147	fields[1].type.u.basic.integer.encoding = lttng_encode_none;
	148
	149	desc->owner = THIS_MODULE;
	150	event->desc = desc;
	151
	152	return 0;
	153
	154	error_fields:
	155	kfree(desc->name);
	156	error_str:
	157	kfree(desc);
	158	return ret;
	159	}
	160
	161	int lttng_kretprobes_register(const char *name,
	162	const char *symbol_name,
	163	uint64_t offset,
	164	uint64_t addr,
a90917c3 MD	165	struct lttng_event *event_entry,
a90917c3 MD	166	struct lttng_event *event_return)
7371f44c MD	167	{
	168	int ret;
	169	struct lttng_krp *lttng_krp;
	170
	171	/* Kprobes expects a NULL symbol name if unused */
	172	if (symbol_name[0] == '\0')
	173	symbol_name = NULL;
	174
	175	ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY);
	176	if (ret)
	177	goto error;
	178	ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN);
	179	if (ret)
	180	goto event_return_error;
	181	lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL);
	182	if (!lttng_krp)
	183	goto krp_error;
	184	lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry;
	185	lttng_krp->krp.handler = lttng_kretprobes_handler_return;
	186	if (symbol_name) {
	187	char *alloc_symbol;
	188
	189	alloc_symbol = kstrdup(symbol_name, GFP_KERNEL);
	190	if (!alloc_symbol) {
	191	ret = -ENOMEM;
	192	goto name_error;
	193	}
	194	lttng_krp->krp.kp.symbol_name =
	195	alloc_symbol;
	196	event_entry->u.kretprobe.symbol_name =
	197	alloc_symbol;
	198	event_return->u.kretprobe.symbol_name =
	199	alloc_symbol;
	200	}
	201	lttng_krp->krp.kp.offset = offset;
b2c4e8fb	202	lttng_krp->krp.kp.addr = (void *) (unsigned long) addr;
7371f44c MD	203
	204	/* Allow probe handler to find event structures */
	205	lttng_krp->event[EVENT_ENTRY] = event_entry;
	206	lttng_krp->event[EVENT_RETURN] = event_return;
	207	event_entry->u.kretprobe.lttng_krp = lttng_krp;
	208	event_return->u.kretprobe.lttng_krp = lttng_krp;
	209
	210	/*
	211	* Both events must be unregistered before the kretprobe is
	212	* unregistered. Same for memory allocation.
	213	*/
	214	kref_init(&lttng_krp->kref_alloc);
9c1f4643	215	kref_get(&lttng_krp->kref_alloc); /* inc refcount to 2, no overflow. */
7371f44c	216	kref_init(&lttng_krp->kref_register);
9c1f4643	217	kref_get(&lttng_krp->kref_register); /* inc refcount to 2, no overflow. */
7371f44c MD	218
	219	/*
	220	* Ensure the memory we just allocated don't trigger page faults.
	221	* Well.. kprobes itself puts the page fault handler on the blacklist,
	222	* but we can never be too careful.
	223	*/
ea53823c	224	wrapper_vmalloc_sync_mappings();
7371f44c MD	225
	226	ret = register_kretprobe(&lttng_krp->krp);
	227	if (ret)
	228	goto register_error;
	229	return 0;
	230
	231	register_error:
	232	kfree(lttng_krp->krp.kp.symbol_name);
	233	name_error:
	234	kfree(lttng_krp);
	235	krp_error:
	236	kfree(event_return->desc->fields);
	237	kfree(event_return->desc->name);
	238	kfree(event_return->desc);
	239	event_return_error:
	240	kfree(event_entry->desc->fields);
	241	kfree(event_entry->desc->name);
	242	kfree(event_entry->desc);
	243	error:
	244	return ret;
	245	}
	246	EXPORT_SYMBOL_GPL(lttng_kretprobes_register);
	247
	248	static
	249	void _lttng_kretprobes_unregister_release(struct kref *kref)
	250	{
	251	struct lttng_krp *lttng_krp =
	252	container_of(kref, struct lttng_krp, kref_register);
	253	unregister_kretprobe(&lttng_krp->krp);
	254	}
	255
a90917c3	256	void lttng_kretprobes_unregister(struct lttng_event *event)
7371f44c MD	257	{
	258	kref_put(&event->u.kretprobe.lttng_krp->kref_register,
	259	_lttng_kretprobes_unregister_release);
	260	}
	261	EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister);
	262
	263	static
	264	void _lttng_kretprobes_release(struct kref *kref)
	265	{
	266	struct lttng_krp *lttng_krp =
	267	container_of(kref, struct lttng_krp, kref_alloc);
	268	kfree(lttng_krp->krp.kp.symbol_name);
	269	}
	270
a90917c3	271	void lttng_kretprobes_destroy_private(struct lttng_event *event)
7371f44c MD	272	{
	273	kfree(event->desc->fields);
	274	kfree(event->desc->name);
	275	kfree(event->desc);
	276	kref_put(&event->u.kretprobe.lttng_krp->kref_alloc,
	277	_lttng_kretprobes_release);
	278	}
	279	EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private);
	280
a0493bef MD	281	int lttng_kretprobes_event_enable_state(struct lttng_event *event,
	282	int enable)
	283	{
	284	struct lttng_event *event_return;
	285	struct lttng_krp *lttng_krp;
	286
	287	if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) {
	288	return -EINVAL;
	289	}
	290	if (event->enabled == enable) {
	291	return -EBUSY;
	292	}
	293	lttng_krp = event->u.kretprobe.lttng_krp;
	294	event_return = lttng_krp->event[EVENT_RETURN];
a8f2d0c7 MJ	295	WRITE_ONCE(event->enabled, enable);
a8f2d0c7 MJ	296	WRITE_ONCE(event_return->enabled, enable);
a0493bef MD	297	return 0;
	298	}
	299	EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state);
	300
7371f44c	301	MODULE_LICENSE("GPL and additional rights");
1c124020 MJ	302	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
1c124020 MJ	303	MODULE_DESCRIPTION("LTTng kretprobes probes");
13ab8b0a MD	304	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	305	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	306	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	307	LTTNG_MODULES_EXTRAVERSION);