// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"

#define HASHMAP_SZ 4194304

struct {
        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
        __uint(max_entries, 1000);
        __type(key, int);
        __type(value, int);
        __array(values, struct {
                __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
                __uint(map_flags, BPF_F_NO_PREALLOC);
                __type(key, int);
                __type(value, int);
        });
} array_of_local_storage_maps SEC(".maps");

struct {
        __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
        __uint(max_entries, 1000);
        __type(key, int);
        __type(value, int);
        __array(values, struct {
                __uint(type, BPF_MAP_TYPE_HASH);
                __uint(max_entries, HASHMAP_SZ);
                __type(key, int);
                __type(value, int);
        });
} array_of_hash_maps SEC(".maps");

long important_hits;
long hits;

/* set from user-space */
const volatile unsigned int use_hashmap;
const volatile unsigned int hashmap_num_keys;
const volatile unsigned int num_maps;
const volatile unsigned int interleave;

struct loop_ctx {
        struct task_struct *task;
        long loop_hits;
        long loop_important_hits;
};

static int do_lookup(unsigned int elem, struct loop_ctx *lctx)
{
        void *map, *inner_map;
        int idx = 0;

        if (use_hashmap)
                map = &array_of_hash_maps;
        else
                map = &array_of_local_storage_maps;

        inner_map = bpf_map_lookup_elem(map, &elem);
        if (!inner_map)
                return -1;

        if (use_hashmap) {
                idx = bpf_get_prandom_u32() % hashmap_num_keys;
                bpf_map_lookup_elem(inner_map, &idx);
        } else {
                bpf_task_storage_get(inner_map, lctx->task, &idx,
                                     BPF_LOCAL_STORAGE_GET_F_CREATE);
        }

        lctx->loop_hits++;
        if (!elem)
                lctx->loop_important_hits++;
        return 0;
}

static long loop(u32 index, void *ctx)
{
        struct loop_ctx *lctx = (struct loop_ctx *)ctx;
        unsigned int map_idx = index % num_maps;

        do_lookup(map_idx, lctx);
        if (interleave && map_idx % 3 == 0)
                do_lookup(0, lctx);
        return 0;
}

SEC("fentry/" SYS_PREFIX "sys_getpgid")
int get_local(void *ctx)
{
        struct loop_ctx lctx;

        lctx.task = bpf_get_current_task_btf();
        lctx.loop_hits = 0;
        lctx.loop_important_hits = 0;
        bpf_loop(10000, &loop, &lctx, 0);
        __sync_add_and_fetch(&hits, lctx.loop_hits);
        __sync_add_and_fetch(&important_hits, lctx.loop_important_hits);
        return 0;
}

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