Function free_user_stack

kernel/src/memory.rs:835–855

Free frames used for a thread stack given virtual address

(
    stack_end: VirtAddr
)

/// Free frames used for a thread stack
/// given virtual address
pub fn free_user_stack(
    stack_end: VirtAddr
) -> Result<(), &'static str> {
    let addr = stack_end - 1u64; // Address in last page
    let table = active_level_1_table_containing(addr);

    let memory_info = unsafe {MEMORY_INFO.as_mut().unwrap()};

    let iend = usize::from(addr.p1_index());
    for index in ((iend - 6)..=iend).rev() {
        let entry = &mut table[index];
        if entry.flags().contains(PageTableFlags::WRITABLE) {
            // Free this frame
            memory_info.frame_allocator.deallocate_frame(
                entry.frame().unwrap());
        }
        entry.set_flags(PageTableFlags::empty());
    }

    Ok(())
}