Linux x64 syscall asm in Rust

syscall.rs

pub unsafe fn syscall0(n: isize) -> isize {
    let mut ret: isize;
    asm!(
        "syscall",
        in("rax") n,
        out("rcx") _,
        out("r11") _,
        lateout("rax") ret,
    );
    ret
}

pub unsafe fn syscall1(n: isize, a1: isize) -> isize {
    let mut ret: isize;
    asm!(
        "syscall",
        in("rax") n,
        in("rdi") a1,
        out("rcx") _,
        out("r11") _,
        lateout("rax") ret,
    );
    ret
}

pub unsafe fn syscall2(n: isize, a1: isize, a2: isize) -> isize {
    let mut ret: isize;
    asm!(
        "syscall",
        in("rax") n,
        in("rdi") a1,
        in("rsi") a2,
        out("rcx") _,
        out("r11") _,
        lateout("rax") ret,
    );
    ret
}

pub unsafe fn syscall3(n: isize, a1: isize, a2: isize, a3: isize) -> isize {
    let mut ret: isize;
    asm!(
        "syscall",
        in("rax") n,
        in("rdi") a1,
        in("rsi") a2,
        in("rdx") a3,
        out("rcx") _,
        out("r11") _,
        lateout("rax") ret,
    );
    ret
}

pub unsafe fn syscall4(n: isize, a1: isize, a2: isize, a3: isize, a4: isize) -> isize {
    let mut ret: isize;
    asm!(
        "syscall",
        in("rax") n,
        in("rdi") a1,
        in("rsi") a2,
        in("rdx") a3,
        in("r10") a4,
        out("rcx") _,
        out("r11") _,
        lateout("rax") ret,
    );
    ret
}

pub unsafe fn syscall5(n: isize, a1: isize, a2: isize, a3: isize, a4: isize, a5: isize) -> isize {
    let mut ret: isize;
    asm!(
        "syscall",
        in("rax") n,
        in("rdi") a1,
        in("rsi") a2,
        in("rdx") a3,
        in("r10") a4,
        in("r8") a5,
        out("rcx") _,
        out("r11") _,
        lateout("rax") ret,
    );
    ret
}

pub unsafe fn syscall6(
    n: isize,
    a1: isize,
    a2: isize,
    a3: isize,
    a4: isize,
    a5: isize,
    a6: isize,
) -> isize {
    let mut ret: usize;
    asm!(
        "syscall",
        in("rax") n,
        in("rdi") a1,
        in("rsi") a2,
        in("rdx") a3,
        in("r10") a4,
        in("r8") a5,
        in("r9") a6,
        out("rcx") _,
        out("r11") _,
        lateout("rax") ret,
    );
    ret as isize
}