// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
#include <linux/bpf.h>
#include <time.h>
#include <bpf/bpf_helpers.h>

#include "bpf_misc.h"

struct inner_map_type {
        __uint(type, BPF_MAP_TYPE_ARRAY);
        __uint(key_size, 4);
        __uint(value_size, 4);
        __uint(max_entries, 1);
} inner_map SEC(".maps");

struct {
        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
        __type(key, int);
        __type(value, int);
        __uint(max_entries, 1);
        __array(values, struct inner_map_type);
} outer_array_map SEC(".maps") = {
        .values = {
                [0] = &inner_map,
        },
};

struct {
        __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
        __type(key, int);
        __type(value, int);
        __uint(max_entries, 1);
        __array(values, struct inner_map_type);
} outer_htab_map SEC(".maps") = {
        .values = {
                [0] = &inner_map,
        },
};

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

int tgid = 0;

static int acc_map_in_map(void *outer_map)
{
        int i, key, value = 0xdeadbeef;
        void *inner_map;

        if ((bpf_get_current_pid_tgid() >> 32) != tgid)
                return 0;

        /* Find nonexistent inner map */
        key = 1;
        inner_map = bpf_map_lookup_elem(outer_map, &key);
        if (inner_map)
                return 0;

        /* Find the old inner map */
        key = 0;
        inner_map = bpf_map_lookup_elem(outer_map, &key);
        if (!inner_map)
                return 0;

        /* Wait for the old inner map to be replaced */
        for (i = 0; i < 2048; i++)
                bpf_map_update_elem(inner_map, &key, &value, 0);

        return 0;
}

SEC("?kprobe/" SYS_PREFIX "sys_getpgid")
int access_map_in_array(void *ctx)
{
        return acc_map_in_map(&outer_array_map);
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int sleepable_access_map_in_array(void *ctx)
{
        return acc_map_in_map(&outer_array_map);
}

SEC("?kprobe/" SYS_PREFIX "sys_getpgid")
int access_map_in_htab(void *ctx)
{
        return acc_map_in_map(&outer_htab_map);
}

SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int sleepable_access_map_in_htab(void *ctx)
{
        return acc_map_in_map(&outer_htab_map);
}