// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Facebook */

#include <linux/bpf.h>
#define BPF_NO_GLOBAL_DATA
#include <bpf/bpf_helpers.h>

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

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

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

volatile int my_pid_var = 0;
volatile int res_var = 0;

SEC("tp/raw_syscalls/sys_enter")
int handle_legacy(void *ctx)
{
        int zero = 0, *my_pid, cur_pid, *my_res;

        my_pid = bpf_map_lookup_elem(&my_pid_map, &zero);
        if (!my_pid)
                return 1;

        cur_pid = bpf_get_current_pid_tgid() >> 32;
        if (cur_pid != *my_pid)
                return 1;

        my_res = bpf_map_lookup_elem(&res_map, &zero);
        if (!my_res)
                return 1;

        if (*my_res == 0)
                /* use bpf_printk() in combination with BPF_NO_GLOBAL_DATA to
                 * force .rodata.str1.1 section that previously caused
                 * problems on old kernels due to libbpf always tried to
                 * create a global data map for it
                 */
                bpf_printk("Legacy-case bpf_printk test, pid %d\n", cur_pid);
        *my_res = 1;

        return *my_res;
}

SEC("tp/raw_syscalls/sys_enter")
int handle_modern(void *ctx)
{
        int cur_pid;

        cur_pid = bpf_get_current_pid_tgid() >> 32;
        if (cur_pid != my_pid_var)
                return 1;

        if (res_var == 0)
                /* we need bpf_printk() to validate libbpf logic around unused
                 * global maps and legacy kernels; see comment in handle_legacy()
                 */
                bpf_printk("Modern-case bpf_printk test, pid %d\n", cur_pid);
        res_var = 1;

        return res_var;
}