Add simple paging, use rust libcore and compile without sse

arch/x86_64/src/memory/area_frame_alloc.rs

@@ -0,0 +1,81 @@
+//! # Area frame allocator
+//! Some code was borrowed from [Phil Opp's Blog](http://os.phil-opp.com/allocating-frames.html)
+
+use paging::PhysicalAddress;
+
+use super::{Frame, FrameAllocator, MemoryArea, MemoryAreaIter};
+
+
+pub struct AreaFrameAllocator {
+    next_free_frame: Frame,
+    current_area: Option<&'static MemoryArea>,
+    areas: MemoryAreaIter,
+    kernel_start: Frame,
+    kernel_end: Frame
+}
+
+impl AreaFrameAllocator {
+    pub fn new(kernel_start: usize, kernel_end: usize, memory_areas: MemoryAreaIter) -> AreaFrameAllocator {
+        let mut allocator = AreaFrameAllocator {
+            next_free_frame: Frame::containing_address(PhysicalAddress::new(0)),
+            current_area: None,
+            areas: memory_areas,
+            kernel_start: Frame::containing_address(PhysicalAddress::new(kernel_start)),
+            kernel_end: Frame::containing_address(PhysicalAddress::new(kernel_end))
+        };
+        allocator.choose_next_area();
+        allocator
+    }
+
+    fn choose_next_area(&mut self) {
+        self.current_area = self.areas.clone().filter(|area| {
+            let address = area.base_addr + area.length - 1;
+            Frame::containing_address(PhysicalAddress::new(address as usize)) >= self.next_free_frame
+        }).min_by_key(|area| area.base_addr);
+
+        if let Some(area) = self.current_area {
+            let start_frame = Frame::containing_address(PhysicalAddress::new(area.base_addr as usize));
+            if self.next_free_frame < start_frame {
+                self.next_free_frame = start_frame;
+            }
+        }
+    }
+}
+
+impl FrameAllocator for AreaFrameAllocator {
+    fn allocate_frame(&mut self) -> Option<Frame> {
+        if let Some(area) = self.current_area {
+            // "Clone" the frame to return it if it's free. Frame doesn't
+            // implement Clone, but we can construct an identical frame.
+            let frame = Frame{ number: self.next_free_frame.number };
+
+            // the last frame of the current area
+            let current_area_last_frame = {
+                let address = area.base_addr + area.length - 1;
+                Frame::containing_address(PhysicalAddress::new(address as usize))
+            };
+
+            if frame > current_area_last_frame {
+                // all frames of current area are used, switch to next area
+                self.choose_next_area();
+            } else if frame >= self.kernel_start && frame <= self.kernel_end {
+                // `frame` is used by the kernel
+                self.next_free_frame = Frame {
+                    number: self.kernel_end.number + 1
+                };
+            } else {
+                // frame is unused, increment `next_free_frame` and return it
+                self.next_free_frame.number += 1;
+                return Some(frame);
+            }
+            // `frame` was not valid, try it again with the updated `next_free_frame`
+            self.allocate_frame()
+        } else {
+            None // no free frames left
+        }
+    }
+
+    fn deallocate_frame(&mut self, frame: Frame) {
+        unimplemented!()
+    }
+}

arch/x86_64/src/memory/mod.rs

@@ -0,0 +1,109 @@
+//! # Memory management
+//! Some code was borrowed from [Phil Opp's Blog](http://os.phil-opp.com/allocating-frames.html)
+
+pub use paging::{PAGE_SIZE, PhysicalAddress};
+
+use self::area_frame_alloc::AreaFrameAllocator;
+
+pub mod area_frame_alloc;
+
+/// The current memory map. It's size is maxed out to 512 entries, due to it being
+/// from 0x500 to 0x5000 (800 is the absolute total)
+static mut MEMORY_MAP: [MemoryArea; 512] = [MemoryArea { base_addr: 0, length: 0, _type: 0, acpi: 0 }; 512];
+
+/// Memory does not exist
+const MEMORY_AREA_NULL: u32 = 0;
+
+/// Memory is free to use
+const MEMORY_AREA_FREE: u32 = 1;
+
+/// Memory is reserved
+const MEMORY_AREA_RESERVED: u32 = 2;
+
+/// Memory is used by ACPI, and can be reclaimed
+const MEMORY_AREA_ACPI: u32 = 3;
+
+#[derive(Clone)]
+pub struct MemoryAreaIter {
+    _type: u32,
+    i: usize
+}
+
+impl MemoryAreaIter {
+    fn new(_type: u32) -> Self {
+        MemoryAreaIter {
+            _type: _type,
+            i: 0
+        }
+    }
+}
+
+impl Iterator for MemoryAreaIter {
+    type Item = &'static MemoryArea;
+    fn next(&mut self) -> Option<Self::Item> {
+        while self.i < unsafe { MEMORY_MAP.len() } {
+            let entry = unsafe { &MEMORY_MAP[self.i] };
+            self.i += 1;
+            if entry._type == self._type {
+                return Some(entry);
+            }
+        }
+        None
+    }
+}
+
+/// Init memory module
+/// Must be called once, and only once,
+pub unsafe fn init(kernel_start: usize, kernel_end: usize) -> AreaFrameAllocator {
+    // Copy memory map from bootloader location
+    for (i, mut entry) in MEMORY_MAP.iter_mut().enumerate() {
+        *entry = *(0x500 as *const MemoryArea).offset(i as isize);
+        if entry.length > 0 {
+            println!("{:?}", entry);
+        }
+    }
+
+    AreaFrameAllocator::new(kernel_start, kernel_end, MemoryAreaIter::new(MEMORY_AREA_FREE))
+}
+
+/// A memory map area
+#[derive(Copy, Clone, Debug, Default)]
+#[repr(packed)]
+pub struct MemoryArea {
+    pub base_addr: u64,
+    pub length: u64,
+    pub _type: u32,
+    pub acpi: u32
+}
+
+/// A frame, allocated by the frame allocator.
+/// Do not add more derives, or make anything `pub`!
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Frame {
+    number: usize
+}
+
+impl Frame {
+    /// Create a frame containing `address`
+    pub fn containing_address(address: PhysicalAddress) -> Frame {
+        Frame {
+            number: address.get() / PAGE_SIZE
+        }
+    }
+
+    /// Get the address of this frame
+    pub fn start_address(&self) -> PhysicalAddress {
+        PhysicalAddress::new(self.number * PAGE_SIZE)
+    }
+
+    fn clone(&self) -> Frame {
+        Frame {
+            number: self.number
+        }
+    }
+}
+
+pub trait FrameAllocator {
+    fn allocate_frame(&mut self) -> Option<Frame>;
+    fn deallocate_frame(&mut self, frame: Frame);
+}