Function active_level_4_table

bootloader/kernel/src/memory.rs:23–35

Returns a mutable reference to the active level 4 table. This function is unsafe because the caller must guarantee that the complete physical memory is mapped to virtual memory at the passed `physical_memory_offset`. Also, this function must be only called once to avoid aliasing `&mut` references (which is undefined behavior).

(physical_memory_offset: VirtAddr)

/// `physical_memory_offset`. Also, this function must be only called once
/// to avoid aliasing `&mut` references (which is undefined behavior).
unsafe fn active_level_4_table(physical_memory_offset: VirtAddr) -> &'static mut PageTable {
    use x86_64::registers::control::Cr3;

    let (level_4_table_frame, _) = Cr3::read();

    let phys = level_4_table_frame.start_address();

    log::info!("level_4_table_frame.start_address {:?}", phys);
    let virt = physical_memory_offset + phys.as_u64();
    let page_table_ptr: *mut PageTable = virt.as_mut_ptr();

    &mut *page_table_ptr // unsafe
}

pub unsafe fn kern_phy_to_virt(physical_memory_offset: VirtAddr, target_phy: PhysAddr) -> VirtAddr {
    let virt = VirtAddr::new(physical_memory_offset.as_u64() + target_phy.as_u64());