1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3
4 #ifndef _CGRP_KFUNC_COMMON_H
5 #define _CGRP_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 __cgrps_kfunc_map_value {
13 struct cgroup __kptr * cgrp;
14 };
15
16 struct {
17 __uint(type, BPF_MAP_TYPE_HASH);
18 __type(key, int);
19 __type(value, struct __cgrps_kfunc_map_value);
20 __uint(max_entries, 1);
21 } __cgrps_kfunc_map SEC(".maps");
22
23 struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
24 void bpf_cgroup_release(struct cgroup *p) __ksym;
25 struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym;
26 struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
27 void bpf_rcu_read_lock(void) __ksym;
28 void bpf_rcu_read_unlock(void) __ksym;
29
30 static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp)
31 {
32 s32 id;
33 long status;
34
35 status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
36 if (status)
37 return NULL;
38
39 return bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
40 }
41
42 static inline int cgrps_kfunc_map_insert(struct cgroup *cgrp)
43 {
44 struct __cgrps_kfunc_map_value local, *v;
45 long status;
46 struct cgroup *acquired, *old;
47 s32 id;
48
49 status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
50 if (status)
51 return status;
52
53 local.cgrp = NULL;
54 status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);
55 if (status)
56 return status;
57
58 v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
59 if (!v) {
60 bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
61 return -ENOENT;
62 }
63
64 acquired = bpf_cgroup_acquire(cgrp);
65 if (!acquired) {
66 bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
67 return -ENOENT;
68 }
69
70 old = bpf_kptr_xchg(&v->cgrp, acquired);
71 if (old) {
72 bpf_cgroup_release(old);
73 return -EEXIST;
74 }
75
76 return 0;
77 }
78
79 #endif /* _CGRP_KFUNC_COMMON_H */
80
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