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

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

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

static
size_t vppid_get_size(size_t offset)
{
	size_t size = 0;

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

static
void vppid_record(struct lttng_kernel_ctx_field *field,
		  struct lib_ring_buffer_ctx *ctx,
		  struct lttng_channel *chan)
{
	struct task_struct *parent;
	pid_t vppid;

	/*
	 * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
	 * the current thread nsproxy to perform the lookup.
	 */

	/*
	 * TODO: when we eventually add RCU subsystem instrumentation,
	 * taking the rcu read lock here will trigger RCU tracing
	 * recursively. We should modify the kernel synchronization so
	 * it synchronizes both for RCU and RCU sched, and rely on
	 * rcu_read_lock_sched_notrace.
	 */

	rcu_read_lock();
	parent = rcu_dereference(current->real_parent);
	if (!current->nsproxy)
		vppid = 0;
	else
		vppid = task_tgid_vnr(parent);
	rcu_read_unlock();
	lib_ring_buffer_align_ctx(ctx, lttng_alignof(vppid));
	chan->ops->event_write(ctx, &vppid, sizeof(vppid));
}

static
void vppid_get_value(struct lttng_kernel_ctx_field *field,
		struct lttng_probe_ctx *lttng_probe_ctx,
		union lttng_ctx_value *value)
{
	struct task_struct *parent;
	pid_t vppid;

	/*
	 * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
	 * the current thread nsproxy to perform the lookup.
	 */

	/*
	 * TODO: when we eventually add RCU subsystem instrumentation,
	 * taking the rcu read lock here will trigger RCU tracing
	 * recursively. We should modify the kernel synchronization so
	 * it synchronizes both for RCU and RCU sched, and rely on
	 * rcu_read_lock_sched_notrace.
	 */

	rcu_read_lock();
	parent = rcu_dereference(current->real_parent);
	if (!current->nsproxy)
		vppid = 0;
	else
		vppid = task_tgid_vnr(parent);
	rcu_read_unlock();
	value->s64 = vppid;
}

static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
	lttng_kernel_static_event_field("vppid",
		lttng_kernel_static_type_integer_from_type(pid_t, __BYTE_ORDER, 10),
		false, false, false),
	vppid_get_size,
	NULL,
	vppid_record,
	vppid_get_value,
	NULL, NULL);

int lttng_add_vppid_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_vppid_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-vppid.c
b64bc438 MD	4	*
	5	* LTTng vPPID context.
	6	*
886d51a3	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
b64bc438 MD	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/slab.h>
	12	#include <linux/sched.h>
	13	#include <linux/syscalls.h>
2df37e95	14	#include <lttng/events.h>
437d5aa5	15	#include <lttng/events-internal.h>
24591303	16	#include <ringbuffer/frontend_types.h>
241ae9a8	17	#include <wrapper/vmalloc.h>
2df37e95	18	#include <lttng/tracer.h>
b64bc438 MD	19
	20	static
	21	size_t vppid_get_size(size_t offset)
	22	{
	23	size_t size = 0;
	24
a90917c3	25	size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
b64bc438 MD	26	size += sizeof(pid_t);
	27	return size;
	28	}
	29
	30	static
437d5aa5	31	void vppid_record(struct lttng_kernel_ctx_field *field,
b64bc438	32	struct lib_ring_buffer_ctx *ctx,
a90917c3	33	struct lttng_channel *chan)
b64bc438	34	{
90f96adf	35	struct task_struct *parent;
b64bc438 MD	36	pid_t vppid;
b64bc438 MD	37
90f96adf	38	/*
de544ea5 MD	39	* current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
de544ea5 MD	40	* the current thread nsproxy to perform the lookup.
90f96adf	41	*/
1638c9b4 MD	42
	43	/*
	44	* TODO: when we eventually add RCU subsystem instrumentation,
	45	* taking the rcu read lock here will trigger RCU tracing
	46	* recursively. We should modify the kernel synchronization so
	47	* it synchronizes both for RCU and RCU sched, and rely on
	48	* rcu_read_lock_sched_notrace.
	49	*/
	50
b64bc438	51	rcu_read_lock();
90f96adf	52	parent = rcu_dereference(current->real_parent);
de544ea5	53	if (!current->nsproxy)
90f96adf MD	54	vppid = 0;
	55	else
	56	vppid = task_tgid_vnr(parent);
b64bc438	57	rcu_read_unlock();
a90917c3	58	lib_ring_buffer_align_ctx(ctx, lttng_alignof(vppid));
b64bc438 MD	59	chan->ops->event_write(ctx, &vppid, sizeof(vppid));
	60	}
	61
f127e61e	62	static
437d5aa5	63	void vppid_get_value(struct lttng_kernel_ctx_field *field,
79150a49	64	struct lttng_probe_ctx *lttng_probe_ctx,
f127e61e MD	65	union lttng_ctx_value *value)
	66	{
	67	struct task_struct *parent;
	68	pid_t vppid;
	69
	70	/*
	71	* current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
	72	* the current thread nsproxy to perform the lookup.
	73	*/
	74
	75	/*
	76	* TODO: when we eventually add RCU subsystem instrumentation,
	77	* taking the rcu read lock here will trigger RCU tracing
	78	* recursively. We should modify the kernel synchronization so
	79	* it synchronizes both for RCU and RCU sched, and rely on
	80	* rcu_read_lock_sched_notrace.
	81	*/
	82
	83	rcu_read_lock();
	84	parent = rcu_dereference(current->real_parent);
	85	if (!current->nsproxy)
	86	vppid = 0;
	87	else
	88	vppid = task_tgid_vnr(parent);
	89	rcu_read_unlock();
	90	value->s64 = vppid;
	91	}
	92
437d5aa5 MD	93	static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
	94	lttng_kernel_static_event_field("vppid",
	95	lttng_kernel_static_type_integer_from_type(pid_t, __BYTE_ORDER, 10),
	96	false, false, false),
	97	vppid_get_size,
	98	NULL,
	99	vppid_record,
	100	vppid_get_value,
	101	NULL, NULL);
	102
	103	int lttng_add_vppid_to_ctx(struct lttng_kernel_ctx **ctx)
b64bc438	104	{
437d5aa5	105	int ret;
b64bc438	106
437d5aa5	107	if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
44252f0f	108	return -EEXIST;
437d5aa5	109	ret = lttng_kernel_context_append(ctx, ctx_field);
263b6c88	110	wrapper_vmalloc_sync_mappings();
437d5aa5	111	return ret;
b64bc438 MD	112	}
b64bc438 MD	113	EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx);