[deliverable/lttng-modules.git] / probes / lttng-ftrace.c

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

/*
 * Ftrace function tracer does not seem to provide synchronization between probe
 * teardown and callback execution. Therefore, we make this module permanently
 * loaded (unloadable).
 *
 * TODO: Move to register_ftrace_function() (which is exported for
 * modules) for Linux >= 3.0. It is faster (only enables the selected
 * functions), and will stay there.
 */

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

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
static
void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip,
		struct trace_array *tr, struct ftrace_probe_ops *ops,
		void *data)
{
	struct lttng_event *event = data;
	struct lttng_probe_ctx lttng_probe_ctx = {
		.event = event,
		.interruptible = !irqs_disabled(),
	};
	struct lttng_channel *chan = event->chan;
	struct lib_ring_buffer_ctx ctx;
	struct {
		unsigned long ip;
		unsigned long parent_ip;
	} payload;
	int ret;

	if (unlikely(!READ_ONCE(chan->session->active)))
		return;
	if (unlikely(!READ_ONCE(chan->enabled)))
		return;
	if (unlikely(!READ_ONCE(event->enabled)))
		return;

	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;
	payload.ip = ip;
	payload.parent_ip = parent_ip;
	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	chan->ops->event_commit(&ctx);
	return;
}
#else
static
void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
{
	struct lttng_event *event = *data;
	struct lttng_probe_ctx lttng_probe_ctx = {
		.event = event,
		.interruptible = !irqs_disabled(),
	};
	struct lttng_channel *chan = event->chan;
	struct lib_ring_buffer_ctx ctx;
	struct {
		unsigned long ip;
		unsigned long parent_ip;
	} payload;
	int ret;

	if (unlikely(!READ_ONCE(chan->session->active)))
		return;
	if (unlikely(!READ_ONCE(chan->enabled)))
		return;
	if (unlikely(!READ_ONCE(event->enabled)))
		return;

	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;
	payload.ip = ip;
	payload.parent_ip = parent_ip;
	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	chan->ops->event_commit(&ctx);
	return;
}
#endif

/*
 * Create event description
 */
static
int lttng_create_ftrace_event(const char *name, struct lttng_event *event)
{
	struct lttng_event_field *fields;
	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 = 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;
}

static
struct ftrace_probe_ops lttng_ftrace_ops = {
	.func = lttng_ftrace_handler,
};

int lttng_ftrace_register(const char *name,
			  const char *symbol_name,
			  struct lttng_event *event)
{
	int ret;

	ret = lttng_create_ftrace_event(name, event);
	if (ret)
		goto error;

	event->u.ftrace.symbol_name = kstrdup(symbol_name, GFP_KERNEL);
	if (!event->u.ftrace.symbol_name)
		goto name_error;

	/* Ensure the memory we just allocated don't trigger page faults */
	wrapper_vmalloc_sync_all();

	ret = wrapper_register_ftrace_function_probe(event->u.ftrace.symbol_name,
			&lttng_ftrace_ops, event);
	if (ret < 0)
		goto register_error;
	return 0;

register_error:
	kfree(event->u.ftrace.symbol_name);
name_error:
	kfree(event->desc->name);
	kfree(event->desc);
error:
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_ftrace_register);

void lttng_ftrace_unregister(struct lttng_event *event)
{
	wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
			&lttng_ftrace_ops, event);
}
EXPORT_SYMBOL_GPL(lttng_ftrace_unregister);

void lttng_ftrace_destroy_private(struct lttng_event *event)
{
	kfree(event->u.ftrace.symbol_name);
	kfree(event->desc->fields);
	kfree(event->desc->name);
	kfree(event->desc);
}
EXPORT_SYMBOL_GPL(lttng_ftrace_destroy_private);

int lttng_ftrace_init(void)
{
	wrapper_vmalloc_sync_all();
	return 0;
}
module_init(lttng_ftrace_init)

/*
 * Ftrace takes care of waiting for a grace period (RCU sched) at probe
 * unregistration, and disables preemption around probe call.
 */
void lttng_ftrace_exit(void)
{
}
module_exit(lttng_ftrace_exit)

MODULE_LICENSE("GPL and additional rights");
MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
MODULE_DESCRIPTION("LTTng ftrace probes");
MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	LTTNG_MODULES_EXTRAVERSION);
Commit	Line	Data
	1	/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
	2	*
	3	* probes/lttng-ftrace.c
	4	*
	5	* LTTng function tracer integration module.
	6	*
	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*/
	9
	10	/*
	11	* Ftrace function tracer does not seem to provide synchronization between probe
	12	* teardown and callback execution. Therefore, we make this module permanently
	13	* loaded (unloadable).
	14	*
	15	* TODO: Move to register_ftrace_function() (which is exported for
	16	* modules) for Linux >= 3.0. It is faster (only enables the selected
	17	* functions), and will stay there.
	18	*/
	19
	20	#include <linux/module.h>
	21	#include <linux/ftrace.h>
	22	#include <linux/slab.h>
	23	#include <lttng-events.h>
	24	#include <wrapper/ringbuffer/frontend_types.h>
	25	#include <wrapper/ftrace.h>
	26	#include <wrapper/vmalloc.h>
	27	#include <lttng-tracer.h>
	28
	29	#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
	30	static
	31	void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip,
	32	struct trace_array tr, struct ftrace_probe_ops ops,
	33	void *data)
	34	{
	35	struct lttng_event *event = data;
	36	struct lttng_probe_ctx lttng_probe_ctx = {
	37	.event = event,
	38	.interruptible = !irqs_disabled(),
	39	};
	40	struct lttng_channel *chan = event->chan;
	41	struct lib_ring_buffer_ctx ctx;
	42	struct {
	43	unsigned long ip;
	44	unsigned long parent_ip;
	45	} payload;
	46	int ret;
	47
	48	if (unlikely(!READ_ONCE(chan->session->active)))
	49	return;
	50	if (unlikely(!READ_ONCE(chan->enabled)))
	51	return;
	52	if (unlikely(!READ_ONCE(event->enabled)))
	53	return;
	54
	55	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx,
	56	sizeof(payload), lttng_alignof(payload), -1);
	57	ret = chan->ops->event_reserve(&ctx, event->id);
	58	if (ret < 0)
	59	return;
	60	payload.ip = ip;
	61	payload.parent_ip = parent_ip;
	62	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	63	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	64	chan->ops->event_commit(&ctx);
	65	return;
	66	}
	67	#else
	68	static
	69	void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
	70	{
	71	struct lttng_event event = data;
	72	struct lttng_probe_ctx lttng_probe_ctx = {
	73	.event = event,
	74	.interruptible = !irqs_disabled(),
	75	};
	76	struct lttng_channel *chan = event->chan;
	77	struct lib_ring_buffer_ctx ctx;
	78	struct {
	79	unsigned long ip;
	80	unsigned long parent_ip;
	81	} payload;
	82	int ret;
	83
	84	if (unlikely(!READ_ONCE(chan->session->active)))
	85	return;
	86	if (unlikely(!READ_ONCE(chan->enabled)))
	87	return;
	88	if (unlikely(!READ_ONCE(event->enabled)))
	89	return;
	90
	91	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx,
	92	sizeof(payload), lttng_alignof(payload), -1);
	93	ret = chan->ops->event_reserve(&ctx, event->id);
	94	if (ret < 0)
	95	return;
	96	payload.ip = ip;
	97	payload.parent_ip = parent_ip;
	98	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
	99	chan->ops->event_write(&ctx, &payload, sizeof(payload));
	100	chan->ops->event_commit(&ctx);
	101	return;
	102	}
	103	#endif
	104
	105	/*
	106	* Create event description
	107	*/
	108	static
	109	int lttng_create_ftrace_event(const char name, struct lttng_event event)
	110	{
	111	struct lttng_event_field *fields;
	112	struct lttng_event_desc *desc;
	113	int ret;
	114
	115	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
	116	if (!desc)
	117	return -ENOMEM;
	118	desc->name = kstrdup(name, GFP_KERNEL);
	119	if (!desc->name) {
	120	ret = -ENOMEM;
	121	goto error_str;
	122	}
	123	desc->nr_fields = 2;
	124	desc->fields = fields =
	125	kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
	126	if (!desc->fields) {
	127	ret = -ENOMEM;
	128	goto error_fields;
	129	}
	130	fields[0].name = "ip";
	131	fields[0].type.atype = atype_integer;
	132	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	133	fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	134	fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	135	fields[0].type.u.basic.integer.reverse_byte_order = 0;
	136	fields[0].type.u.basic.integer.base = 16;
	137	fields[0].type.u.basic.integer.encoding = lttng_encode_none;
	138
	139	fields[1].name = "parent_ip";
	140	fields[1].type.atype = atype_integer;
	141	fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
	142	fields[1].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
	143	fields[1].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
	144	fields[1].type.u.basic.integer.reverse_byte_order = 0;
	145	fields[1].type.u.basic.integer.base = 16;
	146	fields[1].type.u.basic.integer.encoding = lttng_encode_none;
	147
	148	desc->owner = THIS_MODULE;
	149	event->desc = desc;
	150
	151	return 0;
	152
	153	error_fields:
	154	kfree(desc->name);
	155	error_str:
	156	kfree(desc);
	157	return ret;
	158	}
	159
	160	static
	161	struct ftrace_probe_ops lttng_ftrace_ops = {
	162	.func = lttng_ftrace_handler,
	163	};
	164
	165	int lttng_ftrace_register(const char *name,
	166	const char *symbol_name,
	167	struct lttng_event *event)
	168	{
	169	int ret;
	170
	171	ret = lttng_create_ftrace_event(name, event);
	172	if (ret)
	173	goto error;
	174
	175	event->u.ftrace.symbol_name = kstrdup(symbol_name, GFP_KERNEL);
	176	if (!event->u.ftrace.symbol_name)
	177	goto name_error;
	178
	179	/* Ensure the memory we just allocated don't trigger page faults */
	180	wrapper_vmalloc_sync_all();
	181
	182	ret = wrapper_register_ftrace_function_probe(event->u.ftrace.symbol_name,
	183	&lttng_ftrace_ops, event);
	184	if (ret < 0)
	185	goto register_error;
	186	return 0;
	187
	188	register_error:
	189	kfree(event->u.ftrace.symbol_name);
	190	name_error:
	191	kfree(event->desc->name);
	192	kfree(event->desc);
	193	error:
	194	return ret;
	195	}
	196	EXPORT_SYMBOL_GPL(lttng_ftrace_register);
	197
	198	void lttng_ftrace_unregister(struct lttng_event *event)
	199	{
	200	wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
	201	&lttng_ftrace_ops, event);
	202	}
	203	EXPORT_SYMBOL_GPL(lttng_ftrace_unregister);
	204
	205	void lttng_ftrace_destroy_private(struct lttng_event *event)
	206	{
	207	kfree(event->u.ftrace.symbol_name);
	208	kfree(event->desc->fields);
	209	kfree(event->desc->name);
	210	kfree(event->desc);
	211	}
	212	EXPORT_SYMBOL_GPL(lttng_ftrace_destroy_private);
	213
	214	int lttng_ftrace_init(void)
	215	{
	216	wrapper_vmalloc_sync_all();
	217	return 0;
	218	}
	219	module_init(lttng_ftrace_init)
	220
	221	/*
	222	* Ftrace takes care of waiting for a grace period (RCU sched) at probe
	223	* unregistration, and disables preemption around probe call.
	224	*/
	225	void lttng_ftrace_exit(void)
	226	{
	227	}
	228	module_exit(lttng_ftrace_exit)
	229
	230	MODULE_LICENSE("GPL and additional rights");
	231	MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
	232	MODULE_DESCRIPTION("LTTng ftrace probes");
	233	MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
	234	__stringify(LTTNG_MODULES_MINOR_VERSION) "."
	235	__stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
	236	LTTNG_MODULES_EXTRAVERSION);