Add simple paging, use rust libcore and compile without sse

arch/x86_64/src/paging/entry.rs

@@ -0,0 +1,62 @@
+//! # Page table entry
+//! Some code borrowed from [Phil Opp's Blog](http://os.phil-opp.com/modifying-page-tables.html)
+
+use memory::Frame;
+
+use super::PhysicalAddress;
+
+/// A page table entry
+pub struct Entry(u64);
+
+bitflags! {
+    pub flags EntryFlags: u64 {
+        const PRESENT =         1 << 0,
+        const WRITABLE =        1 << 1,
+        const USER_ACCESSIBLE = 1 << 2,
+        const WRITE_THROUGH =   1 << 3,
+        const NO_CACHE =        1 << 4,
+        const ACCESSED =        1 << 5,
+        const DIRTY =           1 << 6,
+        const HUGE_PAGE =       1 << 7,
+        const GLOBAL =          1 << 8,
+        const NO_EXECUTE =      1 << 63,
+    }
+}
+
+pub const ADDRESS_MASK: usize = 0x000fffff_fffff000;
+
+impl Entry {
+    /// Is the entry unused?
+    pub fn is_unused(&self) -> bool {
+        self.0 == 0
+    }
+
+    /// Make the entry unused
+    pub fn set_unused(&mut self) {
+        self.0 = 0;
+    }
+
+    /// Get the address this page references
+    pub fn address(&self) -> PhysicalAddress {
+        PhysicalAddress::new(self.0 as usize & ADDRESS_MASK)
+    }
+
+    /// Get the current entry flags
+    pub fn flags(&self) -> EntryFlags {
+        EntryFlags::from_bits_truncate(self.0)
+    }
+
+    /// Get the associated frame, if available
+    pub fn pointed_frame(&self) -> Option<Frame> {
+        if self.flags().contains(PRESENT) {
+            Some(Frame::containing_address(self.address()))
+        } else {
+            None
+        }
+    }
+
+    pub fn set(&mut self, frame: Frame, flags: EntryFlags) {
+        debug_assert!(frame.start_address().get() & !ADDRESS_MASK == 0);
+        self.0 = (frame.start_address().get() as u64) | flags.bits();
+    }
+}

arch/x86_64/src/paging/mod.rs

@@ -0,0 +1,165 @@
+//! # Paging
+//! Some code was borrowed from [Phil Opp's Blog](http://os.phil-opp.com/modifying-page-tables.html)
+
+use core::ptr::Unique;
+
+use memory::{Frame, FrameAllocator};
+
+use self::entry::EntryFlags;
+use self::table::{Table, Level4};
+
+pub mod entry;
+pub mod table;
+
+/// Number of entries per page table
+pub const ENTRY_COUNT: usize = 512;
+
+/// Size of pages
+pub const PAGE_SIZE: usize = 4096;
+
+/// Initialize paging
+pub unsafe fn init() -> ActivePageTable {
+    ActivePageTable::new()
+}
+
+pub struct ActivePageTable {
+    p4: Unique<Table<Level4>>,
+}
+
+impl ActivePageTable {
+    /// Create a new page table
+    pub unsafe fn new() -> ActivePageTable {
+        ActivePageTable {
+            p4: Unique::new(table::P4),
+        }
+    }
+
+    fn p4(&self) -> &Table<Level4> {
+        unsafe { self.p4.get() }
+    }
+
+    fn p4_mut(&mut self) -> &mut Table<Level4> {
+        unsafe { self.p4.get_mut() }
+    }
+
+    /// Map a page to a frame
+    pub fn map_to<A>(&mut self, page: Page, frame: Frame, flags: EntryFlags, allocator: &mut A)
+        where A: FrameAllocator
+    {
+        let mut p3 = self.p4_mut().next_table_create(page.p4_index(), allocator);
+        let mut p2 = p3.next_table_create(page.p3_index(), allocator);
+        let mut p1 = p2.next_table_create(page.p2_index(), allocator);
+
+        assert!(p1[page.p1_index()].is_unused());
+        p1[page.p1_index()].set(frame, flags | entry::PRESENT);
+    }
+
+    /// Map a page to the next free frame
+    pub fn map<A>(&mut self, page: Page, flags: EntryFlags, allocator: &mut A)
+        where A: FrameAllocator
+    {
+        let frame = allocator.allocate_frame().expect("out of memory");
+        self.map_to(page, frame, flags, allocator)
+    }
+
+    /// Identity map a frame
+    pub fn identity_map<A>(&mut self, frame: Frame, flags: EntryFlags, allocator: &mut A)
+        where A: FrameAllocator
+    {
+        let page = Page::containing_address(VirtualAddress::new(frame.start_address().get()));
+        self.map_to(page, frame, flags, allocator)
+    }
+
+    /// Unmap a page
+    fn unmap<A>(&mut self, page: Page, allocator: &mut A)
+        where A: FrameAllocator
+    {
+        assert!(self.translate(page.start_address()).is_some());
+
+        let p1 = self.p4_mut()
+                     .next_table_mut(page.p4_index())
+                     .and_then(|p3| p3.next_table_mut(page.p3_index()))
+                     .and_then(|p2| p2.next_table_mut(page.p2_index()))
+                     .expect("mapping code does not support huge pages");
+        let frame = p1[page.p1_index()].pointed_frame().unwrap();
+        p1[page.p1_index()].set_unused();
+        // TODO free p(1,2,3) table if empty
+        allocator.deallocate_frame(frame);
+    }
+
+    fn translate_page(&self, page: Page) -> Option<Frame> {
+        self.p4().next_table(page.p4_index())
+            .and_then(|p3| p3.next_table(page.p3_index()))
+            .and_then(|p2| p2.next_table(page.p2_index()))
+            .and_then(|p1| p1[page.p1_index()].pointed_frame())
+    }
+
+    /// Translate a virtual address to a physical one
+    pub fn translate(&self, virtual_address: VirtualAddress) -> Option<PhysicalAddress> {
+        let offset = virtual_address.get() % PAGE_SIZE;
+        self.translate_page(Page::containing_address(virtual_address))
+            .map(|frame| PhysicalAddress::new(frame.start_address().get() + offset))
+    }
+}
+
+/// A physical address.
+#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+pub struct PhysicalAddress(usize);
+
+impl PhysicalAddress {
+    pub fn new(address: usize) -> Self {
+        PhysicalAddress(address)
+    }
+
+    pub fn get(&self) -> usize {
+        self.0
+    }
+}
+
+/// A virtual address.
+#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+pub struct VirtualAddress(usize);
+
+impl VirtualAddress {
+    pub fn new(address: usize) -> Self {
+        VirtualAddress(address)
+    }
+
+    pub fn get(&self) -> usize {
+        self.0
+    }
+}
+
+/// Page
+#[derive(Debug, Clone, Copy)]
+pub struct Page {
+    number: usize
+}
+
+impl Page {
+    fn start_address(&self) -> VirtualAddress {
+        VirtualAddress::new(self.number * PAGE_SIZE)
+    }
+
+    fn p4_index(&self) -> usize {
+        (self.number >> 27) & 0o777
+    }
+
+    fn p3_index(&self) -> usize {
+        (self.number >> 18) & 0o777
+    }
+
+    fn p2_index(&self) -> usize {
+        (self.number >> 9) & 0o777
+    }
+
+    fn p1_index(&self) -> usize {
+        (self.number >> 0) & 0o777
+    }
+
+    pub fn containing_address(address: VirtualAddress) -> Page {
+        assert!(address.get() < 0x0000_8000_0000_0000 || address.get() >= 0xffff_8000_0000_0000,
+            "invalid address: 0x{:x}", address.get());
+        Page { number: address.get() / PAGE_SIZE }
+    }
+}

arch/x86_64/src/paging/table.rs

@@ -0,0 +1,100 @@
+//! # Page table
+//! Code borrowed from [Phil Opp's Blog](http://os.phil-opp.com/modifying-page-tables.html)
+
+use core::marker::PhantomData;
+use core::ops::{Index, IndexMut};
+
+use memory::FrameAllocator;
+
+use super::entry::*;
+use super::ENTRY_COUNT;
+
+pub const P4: *mut Table<Level4> = 0xffffffff_fffff000 as *mut _;
+
+pub trait TableLevel {}
+
+pub enum Level4 {}
+pub enum Level3 {}
+pub enum Level2 {}
+pub enum Level1 {}
+
+impl TableLevel for Level4 {}
+impl TableLevel for Level3 {}
+impl TableLevel for Level2 {}
+impl TableLevel for Level1 {}
+
+pub trait HierarchicalLevel: TableLevel {
+    type NextLevel: TableLevel;
+}
+
+impl HierarchicalLevel for Level4 {
+    type NextLevel = Level3;
+}
+
+impl HierarchicalLevel for Level3 {
+    type NextLevel = Level2;
+}
+
+impl HierarchicalLevel for Level2 {
+    type NextLevel = Level1;
+}
+
+pub struct Table<L: TableLevel> {
+    entries: [Entry; ENTRY_COUNT],
+    level: PhantomData<L>,
+}
+
+impl<L> Table<L> where L: TableLevel {
+    pub fn zero(&mut self) {
+        for entry in self.entries.iter_mut() {
+            entry.set_unused();
+        }
+    }
+}
+
+impl<L> Table<L> where L: HierarchicalLevel {
+    pub fn next_table(&self, index: usize) -> Option<&Table<L::NextLevel>> {
+        self.next_table_address(index).map(|address| unsafe { &*(address as *const _) })
+    }
+
+    pub fn next_table_mut(&mut self, index: usize) -> Option<&mut Table<L::NextLevel>> {
+        self.next_table_address(index).map(|address| unsafe { &mut *(address as *mut _) })
+    }
+
+    pub fn next_table_create<A>(&mut self, index: usize, allocator: &mut A) -> &mut Table<L::NextLevel>
+        where A: FrameAllocator
+    {
+        if self.next_table(index).is_none() {
+            assert!(!self.entries[index].flags().contains(HUGE_PAGE),
+                    "mapping code does not support huge pages");
+            let frame = allocator.allocate_frame().expect("no frames available");
+            self.entries[index].set(frame, PRESENT | WRITABLE);
+            self.next_table_mut(index).unwrap().zero();
+        }
+        self.next_table_mut(index).unwrap()
+    }
+
+    fn next_table_address(&self, index: usize) -> Option<usize> {
+        let entry_flags = self[index].flags();
+        if entry_flags.contains(PRESENT) && !entry_flags.contains(HUGE_PAGE) {
+            let table_address = self as *const _ as usize;
+            Some((table_address << 9) | (index << 12))
+        } else {
+            None
+        }
+    }
+}
+
+impl<L> Index<usize> for Table<L> where L: TableLevel {
+    type Output = Entry;
+
+    fn index(&self, index: usize) -> &Entry {
+        &self.entries[index]
+    }
+}
+
+impl<L> IndexMut<usize> for Table<L> where L: TableLevel {
+    fn index_mut(&mut self, index: usize) -> &mut Entry {
+        &mut self.entries[index]
+    }
+}