[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 <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(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(struct lttng_ctx_field *field,
		struct lib_ring_buffer_ctx *ctx,
		struct lttng_channel *chan)
{
	int prio;

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

static
void prio_get_value(struct lttng_ctx_field *field,
		struct lttng_probe_ctx *lttng_probe_ctx,
		union lttng_ctx_value *value)
{
	value->s64 = wrapper_task_prio_sym(current);
}

int lttng_add_prio_to_ctx(struct lttng_ctx **ctx)
{
	struct lttng_ctx_field *field;
	int ret;

	if (!wrapper_task_prio_sym) {
		ret = wrapper_task_prio_init();
		if (ret)
			return ret;
	}

	field = lttng_append_context(ctx);
	if (!field)
		return -ENOMEM;
	if (lttng_find_context(*ctx, "prio")) {
		lttng_remove_context_field(ctx, field);
		return -EEXIST;
	}
	field->event_field.name = "prio";
	field->event_field.type.atype = atype_integer;
	field->event_field.type.u.integer.size = sizeof(int) * CHAR_BIT;
	field->event_field.type.u.integer.alignment = lttng_alignof(int) * CHAR_BIT;
	field->event_field.type.u.integer.signedness = lttng_is_signed_type(int);
	field->event_field.type.u.integer.reverse_byte_order = 0;
	field->event_field.type.u.integer.base = 10;
	field->event_field.type.u.integer.encoding = lttng_encode_none;
	field->get_size = prio_get_size;
	field->record = prio_record;
	field->get_value = prio_get_value;
	lttng_context_update(*ctx);
	wrapper_vmalloc_sync_mappings();
	return 0;
}
EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx);
Commit	Line	Data
	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
	2	*
	3	* lttng-context-prio.c
	4	*
	5	* LTTng priority context.
	6	*
	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/slab.h>
	12	#include <linux/sched.h>
	13	#include <lttng/events.h>
	14	#include <ringbuffer/frontend_types.h>
	15	#include <wrapper/vmalloc.h>
	16	#include <wrapper/kallsyms.h>
	17	#include <lttng/tracer.h>
	18
	19	static
	20	int (wrapper_task_prio_sym)(struct task_struct t);
	21
	22	int wrapper_task_prio_init(void)
	23	{
	24	wrapper_task_prio_sym = (void *) kallsyms_lookup_funcptr("task_prio");
	25	if (!wrapper_task_prio_sym) {
	26	printk(KERN_WARNING "LTTng: task_prio symbol lookup failed.\n");
	27	return -EINVAL;
	28	}
	29	return 0;
	30	}
	31
	32	/*
	33	* Canary function to check for 'task_prio()' at compile time.
	34	*
	35	* From 'include/linux/sched.h':
	36	*
	37	* extern int task_prio(const struct task_struct *p);
	38	*/
	39	__attribute__((unused)) static
	40	int __canary__task_prio(const struct task_struct *p)
	41	{
	42	return task_prio(p);
	43	}
	44
	45	static
	46	size_t prio_get_size(size_t offset)
	47	{
	48	size_t size = 0;
	49
	50	size += lib_ring_buffer_align(offset, lttng_alignof(int));
	51	size += sizeof(int);
	52	return size;
	53	}
	54
	55	static
	56	void prio_record(struct lttng_ctx_field *field,
	57	struct lib_ring_buffer_ctx *ctx,
	58	struct lttng_channel *chan)
	59	{
	60	int prio;
	61
	62	prio = wrapper_task_prio_sym(current);
	63	lib_ring_buffer_align_ctx(ctx, lttng_alignof(prio));
	64	chan->ops->event_write(ctx, &prio, sizeof(prio));
	65	}
	66
	67	static
	68	void prio_get_value(struct lttng_ctx_field *field,
	69	struct lttng_probe_ctx *lttng_probe_ctx,
	70	union lttng_ctx_value *value)
	71	{
	72	value->s64 = wrapper_task_prio_sym(current);
	73	}
	74
	75	int lttng_add_prio_to_ctx(struct lttng_ctx **ctx)
	76	{
	77	struct lttng_ctx_field *field;
	78	int ret;
	79
	80	if (!wrapper_task_prio_sym) {
	81	ret = wrapper_task_prio_init();
	82	if (ret)
	83	return ret;
	84	}
	85
	86	field = lttng_append_context(ctx);
	87	if (!field)
	88	return -ENOMEM;
	89	if (lttng_find_context(*ctx, "prio")) {
	90	lttng_remove_context_field(ctx, field);
	91	return -EEXIST;
	92	}
	93	field->event_field.name = "prio";
	94	field->event_field.type.atype = atype_integer;
	95	field->event_field.type.u.integer.size = sizeof(int) * CHAR_BIT;
	96	field->event_field.type.u.integer.alignment = lttng_alignof(int) * CHAR_BIT;
	97	field->event_field.type.u.integer.signedness = lttng_is_signed_type(int);
	98	field->event_field.type.u.integer.reverse_byte_order = 0;
	99	field->event_field.type.u.integer.base = 10;
	100	field->event_field.type.u.integer.encoding = lttng_encode_none;
	101	field->get_size = prio_get_size;
	102	field->record = prio_record;
	103	field->get_value = prio_get_value;
	104	lttng_context_update(*ctx);
	105	wrapper_vmalloc_sync_mappings();
	106	return 0;
	107	}
	108	EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx);