1/* SPDX-License-Identifier: GPL-2.0 */
 2/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
 3
 4#ifndef _TASK_KFUNC_COMMON_H
 5#define _TASK_KFUNC_COMMON_H
 6
 7#include <errno.h>
 8#include <vmlinux.h>
 9#include <bpf/bpf_helpers.h>
10#include <bpf/bpf_tracing.h>
11
12struct __tasks_kfunc_map_value {
13	struct task_struct __kptr * task;
14};
15
16struct {
17	__uint(type, BPF_MAP_TYPE_HASH);
18	__type(key, int);
19	__type(value, struct __tasks_kfunc_map_value);
20	__uint(max_entries, 1);
21} __tasks_kfunc_map SEC(".maps");
22
23struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
24void bpf_task_release(struct task_struct *p) __ksym;
25struct task_struct *bpf_task_from_pid(s32 pid) __ksym;
26struct task_struct *bpf_task_from_vpid(s32 vpid) __ksym;
27void bpf_rcu_read_lock(void) __ksym;
28void bpf_rcu_read_unlock(void) __ksym;
29
30static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p)
31{
32	s32 pid;
33	long status;
34
35	status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);
36	if (status)
37		return NULL;
38
39	return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
40}
41
42static inline int tasks_kfunc_map_insert(struct task_struct *p)
43{
44	struct __tasks_kfunc_map_value local, *v;
45	long status;
46	struct task_struct *acquired, *old;
47	s32 pid;
48
49	status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);
50	if (status)
51		return status;
52
53	local.task = NULL;
54	status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);
55	if (status)
56		return status;
57
58	v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
59	if (!v) {
60		bpf_map_delete_elem(&__tasks_kfunc_map, &pid);
61		return -ENOENT;
62	}
63
64	acquired = bpf_task_acquire(p);
65	if (!acquired)
66		return -ENOENT;
67
68	old = bpf_kptr_xchg(&v->task, acquired);
69	if (old) {
70		bpf_task_release(old);
71		return -EEXIST;
72	}
73
74	return 0;
75}
76
77#endif /* _TASK_KFUNC_COMMON_H */

 1/* SPDX-License-Identifier: GPL-2.0 */
 2/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
 3
 4#ifndef _TASK_KFUNC_COMMON_H
 5#define _TASK_KFUNC_COMMON_H
 6
 7#include <errno.h>
 8#include <vmlinux.h>
 9#include <bpf/bpf_helpers.h>
10#include <bpf/bpf_tracing.h>
11
12struct __tasks_kfunc_map_value {
13	struct task_struct __kptr * task;
14};
15
16struct hash_map {
17	__uint(type, BPF_MAP_TYPE_HASH);
18	__type(key, int);
19	__type(value, struct __tasks_kfunc_map_value);
20	__uint(max_entries, 1);
21} __tasks_kfunc_map SEC(".maps");
22
23struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
24void bpf_task_release(struct task_struct *p) __ksym;
25struct task_struct *bpf_task_from_pid(s32 pid) __ksym;
 
26void bpf_rcu_read_lock(void) __ksym;
27void bpf_rcu_read_unlock(void) __ksym;
28
29static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p)
30{
31	s32 pid;
32	long status;
33
34	status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);
35	if (status)
36		return NULL;
37
38	return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
39}
40
41static inline int tasks_kfunc_map_insert(struct task_struct *p)
42{
43	struct __tasks_kfunc_map_value local, *v;
44	long status;
45	struct task_struct *acquired, *old;
46	s32 pid;
47
48	status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);
49	if (status)
50		return status;
51
52	local.task = NULL;
53	status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);
54	if (status)
55		return status;
56
57	v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
58	if (!v) {
59		bpf_map_delete_elem(&__tasks_kfunc_map, &pid);
60		return -ENOENT;
61	}
62
63	acquired = bpf_task_acquire(p);
64	if (!acquired)
65		return -ENOENT;
66
67	old = bpf_kptr_xchg(&v->task, acquired);
68	if (old) {
69		bpf_task_release(old);
70		return -EEXIST;
71	}
72
73	return 0;
74}
75
76#endif /* _TASK_KFUNC_COMMON_H */