1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2022 Bytedance */
3
4#include "vmlinux.h"
5#include <bpf/bpf_helpers.h>
6
7__u64 percpu_array_elem_sum = 0;
8__u64 percpu_hash_elem_sum = 0;
9__u64 percpu_lru_hash_elem_sum = 0;
10const volatile int nr_cpus;
11const volatile int my_pid;
12
13struct {
14 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
15 __uint(max_entries, 1);
16 __type(key, __u32);
17 __type(value, __u64);
18} percpu_array_map SEC(".maps");
19
20struct {
21 __uint(type, BPF_MAP_TYPE_PERCPU_HASH);
22 __uint(max_entries, 1);
23 __type(key, __u64);
24 __type(value, __u64);
25} percpu_hash_map SEC(".maps");
26
27struct {
28 __uint(type, BPF_MAP_TYPE_LRU_PERCPU_HASH);
29 __uint(max_entries, 1);
30 __type(key, __u64);
31 __type(value, __u64);
32} percpu_lru_hash_map SEC(".maps");
33
34struct read_percpu_elem_ctx {
35 void *map;
36 __u64 sum;
37};
38
39static int read_percpu_elem_callback(__u32 index, struct read_percpu_elem_ctx *ctx)
40{
41 __u64 key = 0;
42 __u64 *value;
43
44 value = bpf_map_lookup_percpu_elem(ctx->map, &key, index);
45 if (value)
46 ctx->sum += *value;
47 return 0;
48}
49
50SEC("tp/syscalls/sys_enter_getuid")
51int sysenter_getuid(const void *ctx)
52{
53 struct read_percpu_elem_ctx map_ctx;
54
55 if (my_pid != (bpf_get_current_pid_tgid() >> 32))
56 return 0;
57
58 map_ctx.map = &percpu_array_map;
59 map_ctx.sum = 0;
60 bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
61 percpu_array_elem_sum = map_ctx.sum;
62
63 map_ctx.map = &percpu_hash_map;
64 map_ctx.sum = 0;
65 bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
66 percpu_hash_elem_sum = map_ctx.sum;
67
68 map_ctx.map = &percpu_lru_hash_map;
69 map_ctx.sum = 0;
70 bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
71 percpu_lru_hash_elem_sum = map_ctx.sum;
72
73 return 0;
74}
75
76char _license[] SEC("license") = "GPL";
77

source code of linux/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c