message: Take &mut when returning &mut
  Fixes mut_from_ref
diff: @@ -387,7 +387,7 @@ struct PageTable<L> {
  /// This additional trait is necessary to make use of Rust's specialization feature and provide a default
  /// implementation of some methods.
  trait PageTableMethods {
  - fn get_page_table_entry<S: PageSize>(&self, page: Page<S>) -> Option<PageTableEntry>;
  + fn get_page_table_entry<S: PageSize>(&mut self, page: Page<S>) -> Option<PageTableEntry>;
  fn map_page_in_this_table<S: PageSize>(
  &mut self,
  page: Page<S>,
  @@ -438,7 +438,10 @@ impl<L: PageTableLevel> PageTableMethods for PageTable<L> {
  ///
  /// This is the default implementation called only for PT.
  /// It is overridden by a specialized implementation for all tables with sub tables (all except PT).
  - default fn get_page_table_entry<S: PageSize>(&self, page: Page<S>) -> Option<PageTableEntry> {
  + default fn get_page_table_entry<S: PageSize>(
  + &mut self,
  + page: Page<S>,
  + ) -> Option<PageTableEntry> {
  assert_eq!(L::LEVEL, S::MAP_LEVEL);
  let index = page.table_index::<L>();
  @@ -472,7 +475,7 @@ where
  ///
  /// This is the implementation for all tables with subtables (PML4, PDPT, PDT).
  /// It overrides the default implementation above.
  - fn get_page_table_entry<S: PageSize>(&self, page: Page<S>) -> Option<PageTableEntry> {
  + fn get_page_table_entry<S: PageSize>(&mut self, page: Page<S>) -> Option<PageTableEntry> {
  assert!(L::LEVEL >= S::MAP_LEVEL);
  let index = page.table_index::<L>();
  @@ -534,12 +537,12 @@ where
  /// Returns the next subtable for the given page in the page table hierarchy.
  ///
  /// Must only be called if a page of this size is mapped in a subtable!
  - fn subtable<S: PageSize>(&self, page: Page<S>) -> &mut PageTable<L::SubtableLevel> {
  + fn subtable<S: PageSize>(&mut self, page: Page<S>) -> &mut PageTable<L::SubtableLevel> {
  assert!(L::LEVEL > S::MAP_LEVEL);
  // Calculate the address of the subtable.
  let index = page.table_index::<L>();
  - let table_address = self as *const PageTable<L> as usize;
  + let table_address = self as *mut PageTable<L> as usize;
  let subtable_address = (table_address << PAGE_MAP_BITS) | (index << PAGE_BITS);
  unsafe { &mut *(subtable_address as *mut PageTable<L::SubtableLevel>) }
  }
  