clone

pub fn clone() callconv(.naked) u64

File

Code

pub fn clone() callconv(.naked) u64 {
    // __clone(func, stack, flags, arg, ptid, tls, ctid)
    //         x0,   x1,    w2,    x3,  x4,   x5,  x6
    //
    // syscall(SYS_clone, flags, stack, ptid, tls, ctid)
    //         x8,        x0,    x1,    x2,   x3,  x4
    asm volatile (
        \\      // align stack and save func,arg
        \\      and x1,x1,#-16
        \\      stp x0,x3,[x1,#-16]!
        \\
        \\      // syscall
        \\      uxtw x0,w2
        \\      mov x2,x4
        \\      mov x3,x5
        \\      mov x4,x6
        \\      mov x8,#220 // SYS_clone
        \\      svc #0
        \\
        \\      cbz x0,1f
        \\      // parent
        \\      ret
        \\
        \\      // child
        \\1:
    );
    if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
        \\     .cfi_undefined lr
    );
    asm volatile (
        \\      mov fp, 0
        \\      mov lr, 0
        \\
        \\      ldp x1,x0,[sp],#16
        \\      blr x1
        \\      mov x8,#93 // SYS_exit
        \\      svc #0
    );
}