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scx_helpers: Add pid namespace helpers

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Add pid namespace helpers for translating namespace pids.

Signed-off-by: Daniel Hodges <hodges.daniel.scott@gmail.com>
This commit is contained in:
Daniel Hodges 2024-09-03 11:06:08 -07:00
parent 3e2e78a9ec
commit 8f4e9e5e3b
2 changed files with 98 additions and 0 deletions
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17
scheds/include/scx/namespace.bpf.h Normal file
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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
*/
#ifndef __SCHED_EXT_NAMESPACE_BPF_H
#define __SCHED_EXT_NAMESPACE_BPF_H
#include "vmlinux.h"
struct pid_namespace* get_task_pid_ns(const struct task_struct* task);
struct pid* get_task_pid_ptr(const struct task_struct* task, enum pid_type type);
pid_t get_task_ns_pid(const struct task_struct* task, enum pid_type type);
pid_t get_pid_nr_ns(struct pid* pid, struct pid_namespace* ns);
pid_t get_ns_pid(void);
#endif /* __SCHED_EXT_NAMESPACE_BPF_H */

81
scheds/include/scx/namespace_impl.bpf.h Normal file
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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
*/
#include "namespace.bpf.h"
#include <bpf/bpf_core_read.h>
#include <bpf/bpf_helpers.h>
__hidden struct pid* get_task_pid_ptr(const struct task_struct* task,
enum pid_type type)
{
// Returns the pid pointer of the given task. See get_task_pid_ptr for
// the kernel implementation.
return (type == PIDTYPE_PID) ? BPF_CORE_READ(task, thread_pid) :
BPF_CORE_READ(task, signal, pids[type]);
}
__hidden struct pid_namespace* get_task_pid_ns(const struct task_struct* task,
enum pid_type type)
{
struct pid_namespace* ns;
struct pid* p;
int level;
// See kernel function task_active_pid_ns in pid.c which calls into
// ns_of_pid. Returns the pid namespace of the given task.
if (!task)
task = (struct task_struct*)bpf_get_current_task();
if (!task)
return NULL;
p = get_task_pid_ptr(task, type);
if (!p)
return NULL;
level = BPF_CORE_READ(p, level);
ns = BPF_CORE_READ(p, numbers[level].ns);
return ns;
}
__hidden pid_t get_pid_nr_ns(struct pid* pid, struct pid_namespace* ns)
{
int level, ns_level;
pid_t nr = 0;
/* This function implements the kernel equivalent pid_nr_ns in linux/pid.h */
if (!pid || !ns)
return nr;
level = BPF_CORE_READ(pid, level);
ns_level = BPF_CORE_READ(ns, level);
if (ns_level <= level) {
struct upid upid;
upid = BPF_CORE_READ(pid, numbers[ns_level]);
if (upid.ns == ns)
nr = upid.nr;
}
return nr;
}
__hidden pid_t get_task_ns_pid(const struct task_struct* task)
{
struct pid_namespace* ns;
struct pid* p;
if (!task)
task = (struct task_struct*)bpf_get_current_task();
ns = get_task_pid_ns(task, PIDTYPE_TGID);
p = get_task_pid_ptr(task, PIDTYPE_PID);
return get_pid_nr_ns(p, ns);
}
__hidden pid_t get_ns_pid(void)
{
return get_task_ns_pid(NULL);
}