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
12 struct __tasks_kfunc_map_value {
13 struct task_struct __kptr_ref * task;
14 };
15
16 struct 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
23 struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
24 struct task_struct *bpf_task_kptr_get(struct task_struct **pp) __ksym;
25 void bpf_task_release(struct task_struct *p) __ksym;
26 struct task_struct *bpf_task_from_pid(s32 pid) __ksym;
27
tasks_kfunc_map_value_lookup(struct task_struct * p)28 static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p)
29 {
30 s32 pid;
31 long status;
32
33 status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);
34 if (status)
35 return NULL;
36
37 return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
38 }
39
tasks_kfunc_map_insert(struct task_struct * p)40 static inline int tasks_kfunc_map_insert(struct task_struct *p)
41 {
42 struct __tasks_kfunc_map_value local, *v;
43 long status;
44 struct task_struct *acquired, *old;
45 s32 pid;
46
47 status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid);
48 if (status)
49 return status;
50
51 local.task = NULL;
52 status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);
53 if (status)
54 return status;
55
56 v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
57 if (!v) {
58 bpf_map_delete_elem(&__tasks_kfunc_map, &pid);
59 return -ENOENT;
60 }
61
62 acquired = bpf_task_acquire(p);
63 old = bpf_kptr_xchg(&v->task, acquired);
64 if (old) {
65 bpf_task_release(old);
66 return -EEXIST;
67 }
68
69 return 0;
70 }
71
72 #endif /* _TASK_KFUNC_COMMON_H */
73