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
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
#include "bpf_experimental.h"
struct val_t {
long b, c, d;
};
struct elem {
long sum;
struct val_t __percpu_kptr *pc;
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, int);
__type(value, struct elem);
} array SEC(".maps");
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;
const volatile int nr_cpus;
/* Initialize the percpu object */
SEC("?fentry/bpf_fentry_test1")
int BPF_PROG(test_array_map_1)
{
struct val_t __percpu_kptr *p;
struct elem *e;
int index = 0;
e = bpf_map_lookup_elem(&array, &index);
if (!e)
return 0;
p = bpf_percpu_obj_new(struct val_t);
if (!p)
return 0;
p = bpf_kptr_xchg(&e->pc, p);
if (p)
bpf_percpu_obj_drop(p);
return 0;
}
/* Update percpu data */
SEC("?fentry/bpf_fentry_test2")
int BPF_PROG(test_array_map_2)
{
struct val_t __percpu_kptr *p;
struct val_t *v;
struct elem *e;
int index = 0;
e = bpf_map_lookup_elem(&array, &index);
if (!e)
return 0;
p = e->pc;
if (!p)
return 0;
v = bpf_per_cpu_ptr(p, 0);
if (!v)
return 0;
v->c = 1;
v->d = 2;
return 0;
}
int cpu0_field_d, sum_field_c;
/* Summarize percpu data */
SEC("?fentry/bpf_fentry_test3")
int BPF_PROG(test_array_map_3)
{
struct val_t __percpu_kptr *p;
int i, index = 0;
struct val_t *v;
struct elem *e;
e = bpf_map_lookup_elem(&array, &index);
if (!e)
return 0;
p = e->pc;
if (!p)
return 0;
bpf_for(i, 0, nr_cpus) {
v = bpf_per_cpu_ptr(p, i);
if (v) {
if (i == 0)
cpu0_field_d = v->d;
sum_field_c += v->c;
}
}
return 0;
}
/* Explicitly free allocated percpu data */
SEC("?fentry/bpf_fentry_test4")
int BPF_PROG(test_array_map_4)
{
struct val_t __percpu_kptr *p;
struct elem *e;
int index = 0;
e = bpf_map_lookup_elem(&array, &index);
if (!e)
return 0;
/* delete */
p = bpf_kptr_xchg(&e->pc, NULL);
if (p) {
bpf_percpu_obj_drop(p);
}
return 0;
}
SEC("?fentry.s/bpf_fentry_test1")
int BPF_PROG(test_array_map_10)
{
struct val_t __percpu_kptr *p, *p1;
int i, index = 0;
struct val_t *v;
struct elem *e;
e = bpf_map_lookup_elem(&array, &index);
if (!e)
return 0;
bpf_rcu_read_lock();
p = e->pc;
if (!p) {
p = bpf_percpu_obj_new(struct val_t);
if (!p)
goto out;
p1 = bpf_kptr_xchg(&e->pc, p);
if (p1) {
/* race condition */
bpf_percpu_obj_drop(p1);
}
}
v = bpf_this_cpu_ptr(p);
v->c = 3;
v = bpf_this_cpu_ptr(p);
v->c = 0;
v = bpf_per_cpu_ptr(p, 0);
if (!v)
goto out;
v->c = 1;
v->d = 2;
/* delete */
p1 = bpf_kptr_xchg(&e->pc, NULL);
if (!p1)
goto out;
bpf_for(i, 0, nr_cpus) {
v = bpf_per_cpu_ptr(p, i);
if (v) {
if (i == 0)
cpu0_field_d = v->d;
sum_field_c += v->c;
}
}
/* finally release p */
bpf_percpu_obj_drop(p1);
out:
bpf_rcu_read_unlock();
return 0;
}
char _license[] SEC("license") = "GPL";
|
