Mapping with USER_ACCESSIBLE

[haraldh]

Using the frame allocator to map pages with USER_ACCESSIBLE will create new p3 and p2 pages without USER_ACCESSIBLE.

I had to change

x86_64/src/structures/paging/mapper/mapped_page_table.rs

Lines 463 to 466 in fef3b4f

	entry.set_frame(
	frame.frame(),
	PageTableFlags::PRESENT | PageTableFlags::WRITABLE,
	);

to

                entry.set_frame(
                    frame.frame(),
                    PageTableFlags::PRESENT
                        | PageTableFlags::WRITABLE
                        | PageTableFlags::USER_ACCESSIBLE,
                );

Otherwise a ring3 cannot access the page.

Not sure, if the code traversing the p2 and p3 should also check for USER_ACCESSIBLE and correct that.

[phil-opp]

Thanks for reporting! We're already working on a solution to this in #112. Maybe you can help us find a good solution?