Basic swap framework, temporarily disable SwapManagers

crate/memory/src/cow.rs

@@ -78,12 +78,12 @@ impl<T: PageTable> CowExt<T> {
         }
         use core::mem::uninitialized;
         let mut temp_data: [u8; PAGE_SIZE] = unsafe { uninitialized() };
-        self.read_page(addr, &mut temp_data[..]);
+        temp_data[..].copy_from_slice(self.get_page_slice_mut(addr));
 
         self.unmap_shared(addr);
         self.map(addr, alloc_frame());
 
-        self.write_page(addr, &temp_data[..]);
+        self.get_page_slice_mut(addr).copy_from_slice(&temp_data[..]);
         true
     }
 }

crate/memory/src/lib.rs

@@ -5,7 +5,7 @@ extern crate alloc;
 
 pub mod paging;
 pub mod cow;
-//pub mod swap;
+pub mod swap;
 
 type VirtAddr = usize;
 type PhysAddr = usize;

crate/memory/src/paging/mock_page_table.rs

@@ -19,6 +19,7 @@ pub struct MockEntry {
     dirty: bool,
     writable_shared: bool,
     readonly_shared: bool,
+    swapped: bool,
 }
 
 impl Entry for MockEntry {
@@ -32,7 +33,7 @@ impl Entry for MockEntry {
     fn set_writable(&mut self, value: bool) { self.writable = value; }
     fn set_present(&mut self, value: bool) { self.present = value; }
     fn target(&self) -> usize { self.target }
-
+    fn set_target(&mut self, target: usize) { self.target = target; }
     fn writable_shared(&self) -> bool { self.writable_shared }
     fn readonly_shared(&self) -> bool { self.readonly_shared }
     fn set_shared(&mut self, writable: bool) {
@@ -43,7 +44,8 @@ impl Entry for MockEntry {
         self.writable_shared = false;
         self.readonly_shared = false;
     }
-
+    fn swapped(&self) -> bool { self.swapped }
+    fn set_swapped(&mut self, value: bool) { self.swapped = value; }
     fn user(&self) -> bool { unimplemented!() }
     fn set_user(&mut self, value: bool) { unimplemented!() }
     fn execute(&self) -> bool { unimplemented!() }
@@ -71,15 +73,11 @@ impl PageTable for MockPageTable {
     fn get_entry(&mut self, addr: VirtAddr) -> &mut <Self as PageTable>::Entry {
         &mut self.entries[addr / PAGE_SIZE]
     }
-    fn read_page(&mut self, addr: usize, data: &mut [u8]) {
+    fn get_page_slice_mut<'a,'b>(&'a mut self, addr: VirtAddr) -> &'b mut [u8] {
         self._read(addr);
         let pa = self.translate(addr) & !(PAGE_SIZE - 1);
-        data.copy_from_slice(&self.data[pa..pa + PAGE_SIZE]);
-    }
-    fn write_page(&mut self, addr: usize, data: &[u8]) {
-        self._write(addr);
-        let pa = self.translate(addr) & !(PAGE_SIZE - 1);
-        self.data[pa..pa + PAGE_SIZE].copy_from_slice(data);
+        let data = unsafe{ &mut *(&mut self.data as *mut [u8; PAGE_SIZE * PAGE_COUNT])};
+        &mut data[pa..pa + PAGE_SIZE]
     }
     fn read(&mut self, addr: usize) -> u8 {
         self._read(addr);

crate/memory/src/paging/mod.rs

@@ -15,8 +15,7 @@ pub trait PageTable {
     fn unmap(&mut self, addr: VirtAddr);
     fn get_entry(&mut self, addr: VirtAddr) -> &mut Self::Entry;
     // For testing with mock
-    fn read_page(&mut self, addr: VirtAddr, data: &mut [u8]);
-    fn write_page(&mut self, addr: VirtAddr, data: &[u8]);
+    fn get_page_slice_mut<'a,'b>(&'a mut self, addr: VirtAddr) -> &'b mut [u8];
     fn read(&mut self, addr: VirtAddr) -> u8;
     fn write(&mut self, addr: VirtAddr, data: u8);
 }
@@ -42,6 +41,7 @@ pub trait Entry {
     fn set_present(&mut self, value: bool);
 
     fn target(&self) -> PhysAddr;
+    fn set_target(&mut self, target: PhysAddr);
 
     // For Copy-on-write extension
     fn writable_shared(&self) -> bool;
@@ -49,6 +49,10 @@ pub trait Entry {
     fn set_shared(&mut self, writable: bool);
     fn clear_shared(&mut self);
 
+    // For Swap extension
+    fn swapped(&self) -> bool;
+    fn set_swapped(&mut self, value: bool);
+
     fn user(&self) -> bool;
     fn set_user(&mut self, value: bool);
     fn execute(&self) -> bool;

crate/memory/src/swap/mock_swapper.rs

@@ -1,27 +1,35 @@
 use super::Swapper;
 use alloc::btree_map::BTreeMap;
+use core::mem::uninitialized;
 
+const PAGE_SIZE: usize = 4096;
+
+#[derive(Default)]
 pub struct MockSwapper {
-    map: BTreeMap<usize, [u8; 4096]>,
+    map: BTreeMap<usize, [u8; PAGE_SIZE]>,
 }
 
 impl Swapper for MockSwapper {
-    fn swap_out(&mut self, data: &[u8; 4096]) -> Result<usize, ()> {
+    fn swap_out(&mut self, data: &[u8]) -> Result<usize, ()> {
         let id = self.alloc_id();
-        self.map.insert(id, data.clone());
+        let mut slice: [u8; PAGE_SIZE] = unsafe{ uninitialized() };
+        slice.copy_from_slice(data);
+        self.map.insert(id, slice);
         Ok(id)
     }
 
-    fn swap_update(&mut self, token: usize, data: &[u8; 4096]) -> Result<(), ()> {
+    fn swap_update(&mut self, token: usize, data: &[u8]) -> Result<(), ()> {
         if !self.map.contains_key(&token) {
             return Err(());
         }
-        self.map.insert(token, data.clone());
+        let mut slice: [u8; PAGE_SIZE] = unsafe{ uninitialized() };
+        slice.copy_from_slice(data);
+        self.map.insert(token, slice);
         Ok(())
     }
-    fn swap_in(&mut self, token: usize, data: &mut [u8; 4096]) -> Result<(), ()> {
+    fn swap_in(&mut self, token: usize, data: &mut [u8]) -> Result<(), ()> {
         match self.map.remove(&token) {
-            Some(d) => *data = d,
+            Some(d) => data.copy_from_slice(d.as_ref()),
             None => return Err(()),
         }
         Ok(())
@@ -29,9 +37,6 @@ impl Swapper for MockSwapper {
 }
 
 impl MockSwapper {
-    pub fn new() -> Self {
-        MockSwapper {map: BTreeMap::new()}
-    }
     fn alloc_id(&self) -> usize {
         (0 .. 100usize).find(|i| !self.map.contains_key(i)).unwrap()
     }
@@ -40,7 +45,6 @@ impl MockSwapper {
 #[cfg(test)]
 mod test {
     use super::*;
-    use core::mem::uninitialized;
 
     fn assert_data_eq(data1: &[u8; 4096], data2: &[u8; 4096]) {
         for (&a, &b) in data2.iter().zip(data1.iter()) {
@@ -50,7 +54,7 @@ mod test {
 
     #[test]
     fn swap_out_in() {
-        let mut swapper = MockSwapper::new();
+        let mut swapper = MockSwapper::default();
         let mut data: [u8; 4096] = unsafe{ uninitialized() };
         let data1: [u8; 4096] = unsafe{ uninitialized() };
         let token = swapper.swap_out(&data1).unwrap();
@@ -60,7 +64,7 @@ mod test {
 
     #[test]
     fn swap_update() {
-        let mut swapper = MockSwapper::new();
+        let mut swapper = MockSwapper::default();
         let mut data: [u8; 4096] = unsafe{ uninitialized() };
         let data1: [u8; 4096] = unsafe{ uninitialized() };
         let data2: [u8; 4096] = unsafe{ uninitialized() };
@@ -72,7 +76,7 @@ mod test {
 
     #[test]
     fn invalid_token() {
-        let mut swapper = MockSwapper::new();
+        let mut swapper = MockSwapper::default();
         let mut data: [u8; 4096] = unsafe{ uninitialized() };
         assert_eq!(swapper.swap_in(0, &mut data), Err(()));
     }

crate/memory/src/swap/mod.rs

@@ -1,13 +1,16 @@
-pub use self::fifo::FifoSwapManager;
-pub use self::enhanced_clock::EnhancedClockSwapManager;
-
 use super::*;
-use super::paging::PageTable;
+use super::paging::*;
+use core::ops::{Deref, DerefMut};
+
+//pub use self::fifo::FifoSwapManager;
+//pub use self::enhanced_clock::EnhancedClockSwapManager;
 
-mod fifo;
-mod enhanced_clock;
+//mod fifo;
+//mod enhanced_clock;
+#[cfg(test)]
 mod mock_swapper;
 
+/// Manage all swappable pages, decide which to swap out
 pub trait SwapManager {
     /// Called when tick interrupt occured
     fn tick(&mut self);
@@ -20,11 +23,99 @@ pub trait SwapManager {
 }
 
 pub trait Swapper {
-    fn swap_out(&mut self, data: &[u8; 4096]) -> Result<usize, ()>;
-    fn swap_update(&mut self, token: usize, data: &[u8; 4096]) -> Result<(), ()>;
-    fn swap_in(&mut self, token: usize, data: &mut [u8; 4096]) -> Result<(), ()>;
+    /// Allocate space on device and write data to it.
+    /// Return a token indicating the location.
+    fn swap_out(&mut self, data: &[u8]) -> Result<usize, ()>;
+    /// Update data on device.
+    fn swap_update(&mut self, token: usize, data: &[u8]) -> Result<(), ()>;
+    /// Recover data from device and deallocate the space.
+    fn swap_in(&mut self, token: usize, data: &mut [u8]) -> Result<(), ()>;
+}
+
+/// Wrapper for page table, supporting swap functions
+struct SwapExt<T: PageTable, M: SwapManager, S: Swapper> {
+    page_table: T,
+    swap_manager: M,
+    swapper: S,
+}
+
+impl<T: PageTable, M: SwapManager, S: Swapper> SwapExt<T, M, S> {
+    pub fn new(page_table: T, swap_manager: M, swapper: S) -> Self {
+        SwapExt {
+            page_table,
+            swap_manager,
+            swapper,
+        }
+    }
+    /// Swap out any one of the swapped pages, return the released PhysAddr.
+    pub fn swap_out_any(&mut self) -> Result<PhysAddr, SwapError> {
+        match self.swap_manager.pop() {
+            None => Err(SwapError::NoSwapped),
+            Some(addr) => self.swap_out(addr),
+        }
+    }
+    /// Swap out page of `addr`, return the origin map target.
+    fn swap_out(&mut self, addr: VirtAddr) -> Result<PhysAddr, SwapError> {
+        let data = self.page_table.get_page_slice_mut(addr);
+        let entry = self.page_table.get_entry(addr);
+        if entry.swapped() {
+            return Err(SwapError::AlreadySwapped);
+        }
+        let token = self.swapper.swap_out(data).map_err(|_| SwapError::IOError)?;
+        let target = entry.target();
+        entry.set_target(token * PAGE_SIZE);
+        entry.set_swapped(true);
+        entry.set_present(false);
+        entry.update();
+        Ok(target)
+    }
+    /// Map page of `addr` to `target`, then swap in the data.
+    fn swap_in(&mut self, addr: VirtAddr, target: PhysAddr) -> Result<(), SwapError> {
+        let token = {
+            let entry = self.page_table.get_entry(addr);
+            if !entry.swapped() {
+                return Err(SwapError::NotSwapped);
+            }
+            let token = entry.target() / PAGE_SIZE;
+            entry.set_target(target);
+            entry.set_swapped(false);
+            entry.set_present(true);
+            entry.update();
+            token
+        };
+        let data = self.page_table.get_page_slice_mut(addr);
+        self.swapper.swap_in(token, data).map_err(|_| SwapError::IOError)?;
+        Ok(())
+    }
+    pub fn page_fault_handler(&mut self, addr: VirtAddr, alloc_frame: impl FnOnce() -> PhysAddr) -> bool {
+        {
+            let entry = self.page_table.get_entry(addr);
+            if !entry.swapped() {
+                return false;
+            }
+        }
+        self.swap_in(addr, alloc_frame()).ok().unwrap();
+        true
+    }
+}
+
+pub enum SwapError {
+    AlreadySwapped,
+    NotSwapped,
+    NoSwapped,
+    IOError,
+}
+
+impl<T: PageTable, M: SwapManager, S: Swapper> Deref for SwapExt<T, M, S> {
+    type Target = T;
+
+    fn deref(&self) -> &<Self as Deref>::Target {
+        &self.page_table
+    }
 }
 
-pub trait SwappablePageTable: PageTable {
-    fn swap_out(&mut self, addr: VirtAddr) -> Result<(), ()>;
+impl<T: PageTable, M: SwapManager, S: Swapper> DerefMut for SwapExt<T, M, S> {
+    fn deref_mut(&mut self) -> &mut <Self as Deref>::Target {
+        &mut self.page_table
+    }
 }

src/arch/x86_64/paging/mod.rs

@@ -58,16 +58,9 @@ impl PageTable for ActivePageTable {
         unsafe { &mut *(entry_addr as *mut PageEntry) }
     }
 
-    fn read_page(&mut self, addr: usize, data: &mut [u8]) {
+    fn get_page_slice_mut<'a, 'b>(&'a mut self, addr: VirtAddr) -> &'b mut [u8] {
         use core::slice;
-        let mem = unsafe { slice::from_raw_parts((addr & !0xfffusize) as *const u8, 4096) };
-        data.copy_from_slice(mem);
-    }
-
-    fn write_page(&mut self, addr: usize, data: &[u8]) {
-        use core::slice;
-        let mem = unsafe { slice::from_raw_parts_mut((addr & !0xfffusize) as *mut u8, 4096) };
-        mem.copy_from_slice(data);
+        unsafe { slice::from_raw_parts_mut((addr & !0xfffusize) as *mut u8, PAGE_SIZE) }
     }
 
     fn read(&mut self, addr: usize) -> u8 {
@@ -119,6 +112,10 @@ impl Entry for PageEntry {
     fn set_writable(&mut self, value: bool) { self.as_flags().set(EF::WRITABLE, value); }
     fn set_present(&mut self, value: bool) { self.as_flags().set(EF::PRESENT, value); }
     fn target(&self) -> usize { self.0.addr().as_u64() as usize }
+    fn set_target(&mut self, target: usize) {
+        let flags = self.0.flags();
+        self.0.set_addr(PhysAddr::new(target as u64), flags);
+    }
     fn writable_shared(&self) -> bool { self.0.flags().contains(EF::BIT_10) }
     fn readonly_shared(&self) -> bool { self.0.flags().contains(EF::BIT_9) }
     fn set_shared(&mut self, writable: bool) {
@@ -127,6 +124,8 @@ impl Entry for PageEntry {
         flags.set(EF::BIT_9, !writable);
     }
     fn clear_shared(&mut self) { self.as_flags().remove(EF::BIT_9 | EF::BIT_10); }
+    fn swapped(&self) -> bool { self.0.flags().contains(EF::BIT_11) }
+    fn set_swapped(&mut self, value: bool) { self.as_flags().set(EF::BIT_11, value); }
     fn user(&self) -> bool { self.0.flags().contains(EF::USER_ACCESSIBLE) }
     fn set_user(&mut self, value: bool) {
         self.as_flags().set(EF::USER_ACCESSIBLE, value);

src/memory/mod.rs

@@ -14,7 +14,7 @@ mod memory_set;
 mod stack_allocator;
 mod address;
 
-const PAGE_SIZE: usize = 1 << 12;
+pub const PAGE_SIZE: usize = 1 << 12;
 
 lazy_static! {
     static ref FRAME_ALLOCATOR: Mutex<BitAlloc64K> = Mutex::new(BitAlloc64K::default());