// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#include <vmlinux.h>
#include <linux/version.h>
#include <bpf/bpf_helpers.h>

struct task_struct *bpf_task_from_pid(int pid) __ksym;
void bpf_task_release(struct task_struct *p) __ksym;
int bpf_send_signal_task(struct task_struct *task, int sig, enum pid_type type, u64 value) __ksym;

__u32 sig = 0, pid = 0, status = 0, signal_thread = 0, target_pid = 0;

static __always_inline int bpf_send_signal_test(void *ctx)
{
        struct task_struct *target_task = NULL;
        int ret;
        u64 value;

        if (status != 0 || pid == 0)
                return 0;

        if ((bpf_get_current_pid_tgid() >> 32) == pid) {
                if (target_pid) {
                        target_task = bpf_task_from_pid(target_pid);
                        if (!target_task)
                                return 0;
                        value = 8;
                }

                if (signal_thread) {
                        if (target_pid)
                                ret = bpf_send_signal_task(target_task, sig, PIDTYPE_PID, value);
                        else
                                ret = bpf_send_signal_thread(sig);
                } else {
                        if (target_pid)
                                ret = bpf_send_signal_task(target_task, sig, PIDTYPE_TGID, value);
                        else
                                ret = bpf_send_signal(sig);
                }
                if (ret == 0)
                        status = 1;
        }

        if (target_task)
                bpf_task_release(target_task);

        return 0;
}

SEC("tracepoint/syscalls/sys_enter_nanosleep")
int send_signal_tp(void *ctx)
{
        return bpf_send_signal_test(ctx);
}

SEC("tracepoint/sched/sched_switch")
int send_signal_tp_sched(void *ctx)
{
        return bpf_send_signal_test(ctx);
}

SEC("perf_event")
int send_signal_perf(void *ctx)
{
        return bpf_send_signal_test(ctx);
}

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