88 lines
3 KiB
Rust
88 lines
3 KiB
Rust
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use core::ptr::Unique;
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use memory::{Frame, FrameAllocator};
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use super::{Page, PAGE_SIZE, PhysicalAddress, VirtualAddress};
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use super::entry::{self, EntryFlags};
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use super::table::{self, Table, Level4};
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pub struct Mapper {
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p4: Unique<Table<Level4>>,
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}
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impl Mapper {
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/// Create a new page table
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pub unsafe fn new() -> Mapper {
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Mapper {
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p4: Unique::new(table::P4),
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}
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}
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pub fn p4(&self) -> &Table<Level4> {
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unsafe { self.p4.get() }
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}
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pub fn p4_mut(&mut self) -> &mut Table<Level4> {
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unsafe { self.p4.get_mut() }
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}
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/// Map a page to a frame
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pub fn map_to<A>(&mut self, page: Page, frame: Frame, flags: EntryFlags, allocator: &mut A)
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where A: FrameAllocator
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{
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let mut p3 = self.p4_mut().next_table_create(page.p4_index(), allocator);
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let mut p2 = p3.next_table_create(page.p3_index(), allocator);
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let mut p1 = p2.next_table_create(page.p2_index(), allocator);
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assert!(p1[page.p1_index()].is_unused());
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p1[page.p1_index()].set(frame, flags | entry::PRESENT);
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}
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/// Map a page to the next free frame
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pub fn map<A>(&mut self, page: Page, flags: EntryFlags, allocator: &mut A)
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where A: FrameAllocator
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{
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let frame = allocator.allocate_frame().expect("out of memory");
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self.map_to(page, frame, flags, allocator)
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}
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/// Identity map a frame
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pub fn identity_map<A>(&mut self, frame: Frame, flags: EntryFlags, allocator: &mut A)
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where A: FrameAllocator
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{
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let page = Page::containing_address(VirtualAddress::new(frame.start_address().get()));
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self.map_to(page, frame, flags, allocator)
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}
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/// Unmap a page
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pub fn unmap<A>(&mut self, page: Page, allocator: &mut A)
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where A: FrameAllocator
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{
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assert!(self.translate(page.start_address()).is_some());
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let p1 = self.p4_mut()
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.next_table_mut(page.p4_index())
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.and_then(|p3| p3.next_table_mut(page.p3_index()))
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.and_then(|p2| p2.next_table_mut(page.p2_index()))
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.expect("mapping code does not support huge pages");
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let frame = p1[page.p1_index()].pointed_frame().unwrap();
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p1[page.p1_index()].set_unused();
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// TODO free p(1,2,3) table if empty
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allocator.deallocate_frame(frame);
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}
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pub fn translate_page(&self, page: Page) -> Option<Frame> {
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self.p4().next_table(page.p4_index())
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.and_then(|p3| p3.next_table(page.p3_index()))
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.and_then(|p2| p2.next_table(page.p2_index()))
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.and_then(|p1| p1[page.p1_index()].pointed_frame())
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}
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/// Translate a virtual address to a physical one
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pub fn translate(&self, virtual_address: VirtualAddress) -> Option<PhysicalAddress> {
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let offset = virtual_address.get() % PAGE_SIZE;
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self.translate_page(Page::containing_address(virtual_address))
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.map(|frame| PhysicalAddress::new(frame.start_address().get() + offset))
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}
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}
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