// SPDX-License-Identifier: GPL-2.0
#include <vmlinux.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>

struct map_value {
        struct task_struct __kptr_untrusted *ptr;
};

struct {
        __uint(type, BPF_MAP_TYPE_LRU_HASH);
        __uint(max_entries, 1);
        __type(key, int);
        __type(value, struct map_value);
} lru_map SEC(".maps");

int pid = 0;
int result = 1;

SEC("fentry/bpf_ktime_get_ns")
int printk(void *ctx)
{
        struct map_value v = {};

        if (pid == bpf_get_current_task_btf()->pid)
                bpf_map_update_elem(&lru_map, &(int){0}, &v, 0);
        return 0;
}

SEC("fentry/do_nanosleep")
int nanosleep(void *ctx)
{
        struct map_value val = {}, *v;
        struct task_struct *current;

        bpf_map_update_elem(&lru_map, &(int){0}, &val, 0);
        v = bpf_map_lookup_elem(&lru_map, &(int){0});
        if (!v)
                return 0;
        bpf_map_delete_elem(&lru_map, &(int){0});
        current = bpf_get_current_task_btf();
        v->ptr = current;
        pid = current->pid;
        bpf_ktime_get_ns();
        result = !v->ptr;
        return 0;
}

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