bpf/progs/for_each_hash_map_elem.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /* Copyright (c) 2021 Facebook */
0003 #include "vmlinux.h"
0004 #include <bpf/bpf_helpers.h>
0005
0006 char _license[] SEC("license") = "GPL";
0007
0008 struct {
0009     __uint(type, BPF_MAP_TYPE_HASH);
0010     __uint(max_entries, 3);
0011     __type(key, __u32);
0012     __type(value, __u64);
0013 } hashmap SEC(".maps");
0014
0015 struct {
0016     __uint(type, BPF_MAP_TYPE_PERCPU_HASH);
0017     __uint(max_entries, 1);
0018     __type(key, __u32);
0019     __type(value, __u64);
0020 } percpu_map SEC(".maps");
0021
0022 struct callback_ctx {
0023     struct __sk_buff *ctx;
0024     int input;
0025     int output;
0026 };
0027
0028 static __u64
0029 check_hash_elem(struct bpf_map *map, __u32 *key, __u64 *val,
0030         struct callback_ctx *data)
0031 {
0032     struct __sk_buff *skb = data->ctx;
0033     __u32 k;
0034     __u64 v;
0035
0036     if (skb) {
0037         k = *key;
0038         v = *val;
0039         if (skb->len == 10000 && k == 10 && v == 10)
0040             data->output = 3; /* impossible path */
0041         else
0042             data->output = 4;
0043     } else {
0044         data->output = data->input;
0045         bpf_map_delete_elem(map, key);
0046     }
0047
0048     return 0;
0049 }
0050
0051 __u32 cpu = 0;
0052 __u32 percpu_called = 0;
0053 __u32 percpu_key = 0;
0054 __u64 percpu_val = 0;
0055 int percpu_output = 0;
0056
0057 static __u64
0058 check_percpu_elem(struct bpf_map *map, __u32 *key, __u64 *val,
0059           struct callback_ctx *unused)
0060 {
0061     struct callback_ctx data;
0062
0063     percpu_called++;
0064     cpu = bpf_get_smp_processor_id();
0065     percpu_key = *key;
0066     percpu_val = *val;
0067
0068     data.ctx = 0;
0069     data.input = 100;
0070     data.output = 0;
0071     bpf_for_each_map_elem(&hashmap, check_hash_elem, &data, 0);
0072     percpu_output = data.output;
0073
0074     return 0;
0075 }
0076
0077 int hashmap_output = 0;
0078 int hashmap_elems = 0;
0079 int percpu_map_elems = 0;
0080
0081 SEC("tc")
0082 int test_pkt_access(struct __sk_buff *skb)
0083 {
0084     struct callback_ctx data;
0085
0086     data.ctx = skb;
0087     data.input = 10;
0088     data.output = 0;
0089     hashmap_elems = bpf_for_each_map_elem(&hashmap, check_hash_elem, &data, 0);
0090     hashmap_output = data.output;
0091
0092     percpu_map_elems = bpf_for_each_map_elem(&percpu_map, check_percpu_elem,
0093                          (void *)0, 0);
0094     return 0;
0095 }