clone

pub fn clone() callconv(.naked) u32

File

Code

pub fn clone() callconv(.naked) u32 {
    // __clone(func, stack, flags, arg, ptid, tls, ctid)
    //         a0,   a1,    a2,    a3,  a4,   a5,  a6
    //
    // syscall(SYS_clone, flags, stack, ptid, tls, ctid)
    //         a7         a0,    a1,    a2,   a3,  a4
    asm volatile (
        \\    # Save func and arg to stack
        \\    addi a1, a1, -8
        \\    sw a0, 0(a1)
        \\    sw a3, 4(a1)
        \\
        \\    # Call SYS_clone
        \\    mv a0, a2
        \\    mv a2, a4
        \\    mv a3, a5
        \\    mv a4, a6
        \\    li a7, 220 # SYS_clone
        \\    ecall
        \\
        \\    beqz a0, 1f
        \\    # Parent
        \\    ret
        \\
        \\    # Child
        \\1:
    );
    if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
        \\    .cfi_undefined ra
    );
    asm volatile (
        \\    mv fp, zero
        \\    mv ra, zero
        \\
        \\    lw a1, 0(sp)
        \\    lw a0, 4(sp)
        \\    jalr a1
        \\
        \\    # Exit
        \\    li a7, 93 # SYS_exit
        \\    ecall
    );
}