How to use syscall to create and manage custom system calls in Golang?

Creating and managing custom system calls in Go involves several steps. Here's a step-by-step guide to help you:

Step 1: Define the system call identifier

Open the file that contains the system call definitions (typically under syscall/syscall_linux.go).
Search for the syscall package, and navigate to the Amd64 structure.
Add a constant to define a unique system call number for your custom system call. Make sure it is not already used by any existing system calls.

Example:

const (
    SYS_MY_CUSTOM_CALL = syscall.SYS_ARCH_PRCTL + 1
)

Step 2: Declare the custom system call

Create a new function that will serve as your custom system call.
Import the necessary packages (syscall, unsafe) and include the //go:noescape directive to prevent the compiler from optimizing the call away.
Use the syscall.Syscall or syscall.Syscall6 function to invoke the system call using the previously defined identifier. Ensure the correct number of arguments and registers are used.
The return value should be of type uintptr, and cast it to your desired return type.

Example:

package main

import (
    "syscall"
    "unsafe"
)

//go:noescape
func myCustomCall(arg1, arg2 uintptr) (uintptr, uintptr, uintptr) {
    return syscall.Syscall(SYS_MY_CUSTOM_CALL, arg1, arg2, 0)
}

Step 3: Test the custom system call

Write a simple code snippet to demonstrate the usage of your custom system call.
Pass the arguments required for your custom call and handle any returned values accordingly.

Example:

package main

import "fmt"

func main() {
    ret, _, _ := myCustomCall(uintptr(10), uintptr(20))
    fmt.Println("Custom system call result:", ret)
}

That's it! You've now created and used a custom system call in Go using the syscall package. Remember to compile and run the code on a Linux machine for the system call to work as expected.