Function patch_aarch64_page21 

pub fn patch_aarch64_page21(
    buf: &mut [u8],
    off: usize,
    site_addr: u64,
    target: u64,
) -> Result<(), PatchError>

aarch64 adrp hi21: the PAGE delta (4 KiB pages), split immlo[30:29] / immhi[23:5]. Range ±4 GiB.