/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2020 Facebook */
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>

struct inner_map {
        __uint(type, BPF_MAP_TYPE_ARRAY);
        __uint(max_entries, 1);
        __type(key, int);
        __type(value, int);
} inner_map1 SEC(".maps"),
  inner_map2 SEC(".maps");

struct inner_map_sz2 {
        __uint(type, BPF_MAP_TYPE_ARRAY);
        __uint(max_entries, 2);
        __type(key, int);
        __type(value, int);
} inner_map_sz2 SEC(".maps");

struct outer_arr {
        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
        __uint(max_entries, 3);
        __type(key, int);
        __type(value, int);
        /* it's possible to use anonymous struct as inner map definition here */
        __array(values, struct {
                __uint(type, BPF_MAP_TYPE_ARRAY);
                /* changing max_entries to 2 will fail during load
                 * due to incompatibility with inner_map definition */
                __uint(max_entries, 1);
                __type(key, int);
                __type(value, int);
        });
} outer_arr SEC(".maps") = {
        /* (void *) cast is necessary because we didn't use `struct inner_map`
         * in __inner(values, ...)
         * Actually, a conscious effort is required to screw up initialization
         * of inner map slots, which is a great thing!
         */
        .values = { (void *)&inner_map1, 0, (void *)&inner_map2 },
};

struct inner_map_sz3 {
        __uint(type, BPF_MAP_TYPE_ARRAY);
        __uint(map_flags, BPF_F_INNER_MAP);
        __uint(max_entries, 3);
        __type(key, int);
        __type(value, int);
} inner_map3 SEC(".maps"),
  inner_map4 SEC(".maps");

struct inner_map_sz4 {
        __uint(type, BPF_MAP_TYPE_ARRAY);
        __uint(map_flags, BPF_F_INNER_MAP);
        __uint(max_entries, 5);
        __type(key, int);
        __type(value, int);
} inner_map5 SEC(".maps");

struct outer_arr_dyn {
        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
        __uint(max_entries, 3);
        __type(key, int);
        __type(value, int);
        __array(values, struct {
                __uint(type, BPF_MAP_TYPE_ARRAY);
                __uint(map_flags, BPF_F_INNER_MAP);
                __uint(max_entries, 1);
                __type(key, int);
                __type(value, int);
        });
} outer_arr_dyn SEC(".maps") = {
        .values = {
                [0] = (void *)&inner_map3,
                [1] = (void *)&inner_map4,
                [2] = (void *)&inner_map5,
        },
};

struct outer_hash {
        __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
        __uint(max_entries, 5);
        __type(key, int);
        /* Here everything works flawlessly due to reuse of struct inner_map
         * and compiler will complain at the attempt to use non-inner_map
         * references below. This is great experience.
         */
        __array(values, struct inner_map);
} outer_hash SEC(".maps") = {
        .values = {
                [0] = &inner_map2,
                [4] = &inner_map1,
        },
};

struct sockarr_sz1 {
        __uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
        __uint(max_entries, 1);
        __type(key, int);
        __type(value, int);
} sockarr_sz1 SEC(".maps");

struct sockarr_sz2 {
        __uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
        __uint(max_entries, 2);
        __type(key, int);
        __type(value, int);
} sockarr_sz2 SEC(".maps");

struct outer_sockarr_sz1 {
        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
        __uint(max_entries, 1);
        __type(key, int);
        __type(value, int);
        __array(values, struct sockarr_sz1);
} outer_sockarr SEC(".maps") = {
        .values = { (void *)&sockarr_sz1 },
};

int input = 0;

SEC("raw_tp/sys_enter")
int handle__sys_enter(void *ctx)
{
        struct inner_map *inner_map;
        int key = 0, val;

        inner_map = bpf_map_lookup_elem(&outer_arr, &key);
        if (!inner_map)
                return 1;
        val = input;
        bpf_map_update_elem(inner_map, &key, &val, 0);

        inner_map = bpf_map_lookup_elem(&outer_hash, &key);
        if (!inner_map)
                return 1;
        val = input + 1;
        bpf_map_update_elem(inner_map, &key, &val, 0);

        inner_map = bpf_map_lookup_elem(&outer_arr_dyn, &key);
        if (!inner_map)
                return 1;
        val = input + 2;
        bpf_map_update_elem(inner_map, &key, &val, 0);

        return 0;
}

char _license[] SEC("license") = "GPL";