1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2020 Facebook */
3#include "bpf_iter.h"
4#include <bpf/bpf_helpers.h>
5#include <bpf/bpf_tracing.h>
6
7char _license[] SEC("license") = "GPL";
8
9struct key_t {
10 int a;
11 int b;
12 int c;
13};
14
15struct {
16 __uint(type, BPF_MAP_TYPE_PERCPU_HASH);
17 __uint(max_entries, 3);
18 __type(key, struct key_t);
19 __type(value, __u32);
20} hashmap1 SEC(".maps");
21
22/* will set before prog run */
23volatile const __s32 num_cpus = 0;
24
25/* will collect results during prog run */
26__u32 key_sum_a = 0, key_sum_b = 0, key_sum_c = 0;
27__u32 val_sum = 0;
28
29SEC("iter/bpf_map_elem")
30int dump_bpf_percpu_hash_map(struct bpf_iter__bpf_map_elem *ctx)
31{
32 struct key_t *key = ctx->key;
33 void *pptr = ctx->value;
34 __u32 step;
35 int i;
36
37 if (key == (void *)0 || pptr == (void *)0)
38 return 0;
39
40 key_sum_a += key->a;
41 key_sum_b += key->b;
42 key_sum_c += key->c;
43
44 step = 8;
45 for (i = 0; i < num_cpus; i++) {
46 val_sum += *(__u32 *)pptr;
47 pptr += step;
48 }
49 return 0;
50}
51

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