1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
|
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
char _license[] SEC("license") = "GPL";
const void *user_ptr = NULL;
struct elem {
__u64 pad;
struct bpf_rcu_head rh;
__u64 val;
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, __u32);
__type(value, struct elem);
} arr SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, __u32);
__type(value, struct elem);
} arr2 SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, __u32);
__type(value, __u64);
} plain SEC(".maps");
__u32 key = 0;
static int reclaim(struct bpf_map *map, void *key, void *value)
{
return 0;
}
static int sleepable_reclaim(struct bpf_map *map, void *key, void *value)
{
struct elem *e = value;
bpf_copy_from_user(&e->val, sizeof(e->val), user_ptr);
return 0;
}
SEC("syscall")
__failure __msg("bpf_rcu_head pointer in R1") __msg("doesn't match map pointer in R2")
int mismatch_map(void *ctx)
{
struct elem *e;
e = bpf_map_lookup_elem(&arr, &key);
if (!e)
return 0;
bpf_call_rcu(&e->rh, &arr2, reclaim);
return 0;
}
SEC("syscall")
__failure __msg("map 'plain' has no valid bpf_rcu_head")
int no_rcu_head(void *ctx)
{
__u64 *val;
val = bpf_map_lookup_elem(&plain, &key);
if (!val)
return 0;
bpf_call_rcu((struct bpf_rcu_head *)val, &plain, reclaim);
return 0;
}
SEC("syscall")
__failure __msg("doesn't point to 'struct bpf_rcu_head' that is at 8")
int wrong_offset(void *ctx)
{
struct elem *e;
e = bpf_map_lookup_elem(&arr, &key);
if (!e)
return 0;
bpf_call_rcu((struct bpf_rcu_head *)&e->pad, &arr, reclaim);
return 0;
}
SEC("syscall")
__failure __msg("R1 type=fp expected=map_value")
int rcu_head_on_stack(void *ctx)
{
struct bpf_rcu_head rh;
bpf_call_rcu(&rh, &arr, reclaim);
return 0;
}
SEC("syscall")
__failure __msg("sleepable helper bpf_copy_from_user") __msg("in non-sleepable prog")
int sleepable_callback(void *ctx)
{
struct elem *e;
e = bpf_map_lookup_elem(&arr, &key);
if (!e)
return 0;
bpf_call_rcu(&e->rh, &arr, sleepable_reclaim);
return 0;
}
|
