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/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
*
* 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 <wrapper/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_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_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;
}
int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx)
{
struct lttng_ctx_field *field;
field = lttng_append_context(ctx);
if (!field)
return -ENOMEM;
if (lttng_find_context(*ctx, "vppid")) {
lttng_remove_context_field(ctx, field);
return -EEXIST;
}
field->event_field.name = "vppid";
field->event_field.type.atype = atype_integer;
field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(pid_t);
field->event_field.type.u.basic.integer.reverse_byte_order = 0;
field->event_field.type.u.basic.integer.base = 10;
field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
field->get_size = vppid_get_size;
field->record = vppid_record;
field->get_value = vppid_get_value;
lttng_context_update(*ctx);
wrapper_vmalloc_sync_all();
return 0;
}
EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx);
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