[lttng-modules.git] / src / lttng-context-prio.c

/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
 *
 * lttng-context-prio.c
 *
 * LTTng priority context.
 *
 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

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

static
int (*wrapper_task_prio_sym)(struct task_struct *t);

int wrapper_task_prio_init(void)
{
	wrapper_task_prio_sym = (void *) kallsyms_lookup_funcptr("task_prio");
	if (!wrapper_task_prio_sym) {
		printk(KERN_WARNING "LTTng: task_prio symbol lookup failed.\n");
		return -EINVAL;
	}
	return 0;
}

/*
 * Canary function to check for 'task_prio()' at compile time.
 *
 * From 'include/linux/sched.h':
 *
 *   extern int task_prio(const struct task_struct *p);
 */
__attribute__((unused)) static
int __canary__task_prio(const struct task_struct *p)
{
	return task_prio(p);
}

static
size_t prio_get_size(void *priv, struct lttng_kernel_probe_ctx *probe_ctx, size_t offset)
{
	size_t size = 0;

	size += lib_ring_buffer_align(offset, lttng_alignof(int));
	size += sizeof(int);
	return size;
}

static
void prio_record(void *priv, struct lttng_kernel_probe_ctx *probe_ctx,
		struct lttng_kernel_ring_buffer_ctx *ctx,
		struct lttng_kernel_channel_buffer *chan)
{
	int prio;

	prio = wrapper_task_prio_sym(current);
	chan->ops->event_write(ctx, &prio, sizeof(prio), lttng_alignof(prio));
}

static
void prio_get_value(void *priv,
		struct lttng_kernel_probe_ctx *lttng_probe_ctx,
		struct lttng_ctx_value *value)
{
	value->u.s64 = wrapper_task_prio_sym(current);
}

static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
	lttng_kernel_static_event_field("prio",
		lttng_kernel_static_type_integer_from_type(int, __BYTE_ORDER, 10),
		false, false, false),
	prio_get_size,
	prio_record,
	prio_get_value,
	NULL, NULL);

int lttng_add_prio_to_ctx(struct lttng_kernel_ctx **ctx)
{
	int ret;

	if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
		return -EEXIST;
	ret = lttng_kernel_context_append(ctx, ctx_field);
	wrapper_vmalloc_sync_mappings();
	return ret;
}
EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx);
Commit	Line	Data
b7cdc182	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
9f36eaed	2	*
886d51a3	3	* lttng-context-prio.c
a8ad3613 MD	4	*
	5	* LTTng priority context.
	6	*
886d51a3	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
a8ad3613 MD	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/slab.h>
	12	#include <linux/sched.h>
2df37e95	13	#include <lttng/events.h>
437d5aa5	14	#include <lttng/events-internal.h>
24591303	15	#include <ringbuffer/frontend_types.h>
241ae9a8 MD	16	#include <wrapper/vmalloc.h>
241ae9a8 MD	17	#include <wrapper/kallsyms.h>
2df37e95	18	#include <lttng/tracer.h>
a8ad3613	19
979133c5 MD	20	static
	21	int (wrapper_task_prio_sym)(struct task_struct t);
	22
	23	int wrapper_task_prio_init(void)
	24	{
c539a324	25	wrapper_task_prio_sym = (void *) kallsyms_lookup_funcptr("task_prio");
979133c5 MD	26	if (!wrapper_task_prio_sym) {
	27	printk(KERN_WARNING "LTTng: task_prio symbol lookup failed.\n");
	28	return -EINVAL;
	29	}
	30	return 0;
	31	}
	32
3dfec228 MJ	33	/*
	34	* Canary function to check for 'task_prio()' at compile time.
	35	*
	36	* From 'include/linux/sched.h':
	37	*
	38	* extern int task_prio(const struct task_struct *p);
	39	*/
	40	__attribute__((unused)) static
	41	int __canary__task_prio(const struct task_struct *p)
	42	{
	43	return task_prio(p);
	44	}
	45
a8ad3613	46	static
a92e844e	47	size_t prio_get_size(void priv, struct lttng_kernel_probe_ctx probe_ctx, size_t offset)
a8ad3613 MD	48	{
	49	size_t size = 0;
	50
a90917c3	51	size += lib_ring_buffer_align(offset, lttng_alignof(int));
a8ad3613 MD	52	size += sizeof(int);
	53	return size;
	54	}
	55
	56	static
a92e844e	57	void prio_record(void priv, struct lttng_kernel_probe_ctx probe_ctx,
8a57ec02	58	struct lttng_kernel_ring_buffer_ctx *ctx,
f7d06400	59	struct lttng_kernel_channel_buffer *chan)
a8ad3613 MD	60	{
	61	int prio;
	62
8fefc8a2	63	prio = wrapper_task_prio_sym(current);
f5ffbd77	64	chan->ops->event_write(ctx, &prio, sizeof(prio), lttng_alignof(prio));
a8ad3613 MD	65	}
a8ad3613 MD	66
f127e61e	67	static
2dc781e0	68	void prio_get_value(void *priv,
a92e844e	69	struct lttng_kernel_probe_ctx *lttng_probe_ctx,
2dc781e0	70	struct lttng_ctx_value *value)
f127e61e	71	{
2dc781e0	72	value->u.s64 = wrapper_task_prio_sym(current);
f127e61e MD	73	}
f127e61e MD	74
437d5aa5 MD	75	static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
	76	lttng_kernel_static_event_field("prio",
	77	lttng_kernel_static_type_integer_from_type(int, __BYTE_ORDER, 10),
	78	false, false, false),
	79	prio_get_size,
437d5aa5 MD	80	prio_record,
	81	prio_get_value,
	82	NULL, NULL);
	83
	84	int lttng_add_prio_to_ctx(struct lttng_kernel_ctx **ctx)
a8ad3613	85	{
a8ad3613 MD	86	int ret;
a8ad3613 MD	87
437d5aa5	88	if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
44252f0f	89	return -EEXIST;
437d5aa5	90	ret = lttng_kernel_context_append(ctx, ctx_field);
263b6c88	91	wrapper_vmalloc_sync_mappings();
437d5aa5	92	return ret;
a8ad3613 MD	93	}
a8ad3613 MD	94	EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx);