add os[1-8]-ref for os refereces, add guide, add README

os7-ref/src/mm/address.rs

@@ -0,0 +1,259 @@
+//! Implementation of physical and virtual address and page number.
+use super::PageTableEntry;
+use crate::config::{PAGE_SIZE, PAGE_SIZE_BITS};
+use core::fmt::{self, Debug, Formatter};
+
+/// Definitions
+#[repr(C)]
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub struct PhysAddr(pub usize);
+
+#[repr(C)]
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub struct VirtAddr(pub usize);
+
+#[repr(C)]
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub struct PhysPageNum(pub usize);
+
+#[repr(C)]
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub struct VirtPageNum(pub usize);
+
+/// Debugging
+
+impl Debug for VirtAddr {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.write_fmt(format_args!("VA:{:#x}", self.0))
+    }
+}
+impl Debug for VirtPageNum {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.write_fmt(format_args!("VPN:{:#x}", self.0))
+    }
+}
+impl Debug for PhysAddr {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.write_fmt(format_args!("PA:{:#x}", self.0))
+    }
+}
+impl Debug for PhysPageNum {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.write_fmt(format_args!("PPN:{:#x}", self.0))
+    }
+}
+
+/// T: {PhysAddr, VirtAddr, PhysPageNum, VirtPageNum}
+/// T -> usize: T.0
+/// usize -> T: usize.into()
+
+impl From<usize> for PhysAddr {
+    fn from(v: usize) -> Self {
+        Self(v)
+    }
+}
+impl From<usize> for PhysPageNum {
+    fn from(v: usize) -> Self {
+        Self(v)
+    }
+}
+impl From<usize> for VirtAddr {
+    fn from(v: usize) -> Self {
+        Self(v)
+    }
+}
+impl From<usize> for VirtPageNum {
+    fn from(v: usize) -> Self {
+        Self(v)
+    }
+}
+impl From<PhysAddr> for usize {
+    fn from(v: PhysAddr) -> Self {
+        v.0
+    }
+}
+impl From<PhysPageNum> for usize {
+    fn from(v: PhysPageNum) -> Self {
+        v.0
+    }
+}
+impl From<VirtAddr> for usize {
+    fn from(v: VirtAddr) -> Self {
+        v.0
+    }
+}
+impl From<VirtPageNum> for usize {
+    fn from(v: VirtPageNum) -> Self {
+        v.0
+    }
+}
+
+impl VirtAddr {
+    pub fn floor(&self) -> VirtPageNum {
+        VirtPageNum(self.0 / PAGE_SIZE)
+    }
+    pub fn ceil(&self) -> VirtPageNum {
+        VirtPageNum((self.0 - 1 + PAGE_SIZE) / PAGE_SIZE)
+    }
+    pub fn page_offset(&self) -> usize {
+        self.0 & (PAGE_SIZE - 1)
+    }
+    pub fn aligned(&self) -> bool {
+        self.page_offset() == 0
+    }
+}
+impl From<VirtAddr> for VirtPageNum {
+    fn from(v: VirtAddr) -> Self {
+        assert_eq!(v.page_offset(), 0);
+        v.floor()
+    }
+}
+impl From<VirtPageNum> for VirtAddr {
+    fn from(v: VirtPageNum) -> Self {
+        Self(v.0 << PAGE_SIZE_BITS)
+    }
+}
+impl PhysAddr {
+    pub fn floor(&self) -> PhysPageNum {
+        PhysPageNum(self.0 / PAGE_SIZE)
+    }
+    pub fn ceil(&self) -> PhysPageNum {
+        PhysPageNum((self.0 - 1 + PAGE_SIZE) / PAGE_SIZE)
+    }
+    pub fn page_offset(&self) -> usize {
+        self.0 & (PAGE_SIZE - 1)
+    }
+    pub fn aligned(&self) -> bool {
+        self.page_offset() == 0
+    }
+}
+impl From<PhysAddr> for PhysPageNum {
+    fn from(v: PhysAddr) -> Self {
+        assert_eq!(v.page_offset(), 0);
+        v.floor()
+    }
+}
+impl From<PhysPageNum> for PhysAddr {
+    fn from(v: PhysPageNum) -> Self {
+        Self(v.0 << PAGE_SIZE_BITS)
+    }
+}
+
+impl VirtPageNum {
+    pub fn indexes(&self) -> [usize; 3] {
+        let mut vpn = self.0;
+        let mut idx = [0usize; 3];
+        for i in (0..3).rev() {
+            idx[i] = vpn & 511;
+            vpn >>= 9;
+        }
+        idx
+    }
+}
+
+impl PhysAddr {
+    pub fn get_ref<T>(&self) -> &'static T {
+        unsafe { (self.0 as *const T).as_ref().unwrap() }
+    }
+    pub fn get_mut<T>(&self) -> &'static mut T {
+        unsafe { (self.0 as *mut T).as_mut().unwrap() }
+    }
+}
+impl PhysPageNum {
+    pub fn get_pte_array(&self) -> &'static mut [PageTableEntry] {
+        let pa: PhysAddr = (*self).into();
+        unsafe { core::slice::from_raw_parts_mut(pa.0 as *mut PageTableEntry, 512) }
+    }
+    pub fn get_bytes_array(&self) -> &'static mut [u8] {
+        let pa: PhysAddr = (*self).into();
+        unsafe { core::slice::from_raw_parts_mut(pa.0 as *mut u8, 4096) }
+    }
+    pub fn get_mut<T>(&self) -> &'static mut T {
+        let pa: PhysAddr = (*self).into();
+        pa.get_mut()
+    }
+}
+
+pub trait StepByOne {
+    fn step(&mut self);
+}
+impl StepByOne for VirtPageNum {
+    fn step(&mut self) {
+        self.0 += 1;
+    }
+}
+
+impl StepByOne for PhysPageNum {
+    fn step(&mut self) {
+        self.0 += 1;
+    }
+}
+
+#[derive(Copy, Clone)]
+/// a simple range structure for type T
+pub struct SimpleRange<T>
+where
+    T: StepByOne + Copy + PartialEq + PartialOrd + Debug,
+{
+    l: T,
+    r: T,
+}
+impl<T> SimpleRange<T>
+where
+    T: StepByOne + Copy + PartialEq + PartialOrd + Debug,
+{
+    pub fn new(start: T, end: T) -> Self {
+        assert!(start <= end, "start {:?} > end {:?}!", start, end);
+        Self { l: start, r: end }
+    }
+    pub fn get_start(&self) -> T {
+        self.l
+    }
+    pub fn get_end(&self) -> T {
+        self.r
+    }
+}
+impl<T> IntoIterator for SimpleRange<T>
+where
+    T: StepByOne + Copy + PartialEq + PartialOrd + Debug,
+{
+    type Item = T;
+    type IntoIter = SimpleRangeIterator<T>;
+    fn into_iter(self) -> Self::IntoIter {
+        SimpleRangeIterator::new(self.l, self.r)
+    }
+}
+/// iterator for the simple range structure
+pub struct SimpleRangeIterator<T>
+where
+    T: StepByOne + Copy + PartialEq + PartialOrd + Debug,
+{
+    current: T,
+    end: T,
+}
+impl<T> SimpleRangeIterator<T>
+where
+    T: StepByOne + Copy + PartialEq + PartialOrd + Debug,
+{
+    pub fn new(l: T, r: T) -> Self {
+        Self { current: l, end: r }
+    }
+}
+impl<T> Iterator for SimpleRangeIterator<T>
+where
+    T: StepByOne + Copy + PartialEq + PartialOrd + Debug,
+{
+    type Item = T;
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current == self.end {
+            None
+        } else {
+            let t = self.current;
+            self.current.step();
+            Some(t)
+        }
+    }
+}
+
+/// a simple range structure for virtual page number
+pub type VPNRange = SimpleRange<VirtPageNum>;

os7-ref/src/mm/frame_allocator.rs

@@ -0,0 +1,136 @@
+//! Implementation of [`FrameAllocator`] which
+//! controls all the frames in the operating system.
+
+use super::{PhysAddr, PhysPageNum};
+use crate::config::MEMORY_END;
+use crate::sync::UPSafeCell;
+use alloc::vec::Vec;
+use core::fmt::{self, Debug, Formatter};
+use lazy_static::*;
+
+/// manage a frame which has the same lifecycle as the tracker
+pub struct FrameTracker {
+    pub ppn: PhysPageNum,
+}
+
+impl FrameTracker {
+    pub fn new(ppn: PhysPageNum) -> Self {
+        // page cleaning
+        let bytes_array = ppn.get_bytes_array();
+        for i in bytes_array {
+            *i = 0;
+        }
+        Self { ppn }
+    }
+}
+
+impl Debug for FrameTracker {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.write_fmt(format_args!("FrameTracker:PPN={:#x}", self.ppn.0))
+    }
+}
+
+impl Drop for FrameTracker {
+    fn drop(&mut self) {
+        frame_dealloc(self.ppn);
+    }
+}
+
+trait FrameAllocator {
+    fn new() -> Self;
+    fn alloc(&mut self) -> Option<PhysPageNum>;
+    fn dealloc(&mut self, ppn: PhysPageNum);
+}
+
+/// an implementation for frame allocator
+pub struct StackFrameAllocator {
+    current: usize,
+    end: usize,
+    recycled: Vec<usize>,
+}
+
+impl StackFrameAllocator {
+    pub fn init(&mut self, l: PhysPageNum, r: PhysPageNum) {
+        self.current = l.0;
+        self.end = r.0;
+        info!("last {} Physical Frames.", self.end - self.current);
+    }
+}
+impl FrameAllocator for StackFrameAllocator {
+    fn new() -> Self {
+        Self {
+            current: 0,
+            end: 0,
+            recycled: Vec::new(),
+        }
+    }
+    fn alloc(&mut self) -> Option<PhysPageNum> {
+        if let Some(ppn) = self.recycled.pop() {
+            Some(ppn.into())
+        } else if self.current == self.end {
+            None
+        } else {
+            self.current += 1;
+            Some((self.current - 1).into())
+        }
+    }
+    fn dealloc(&mut self, ppn: PhysPageNum) {
+        let ppn = ppn.0;
+        // validity check
+        if ppn >= self.current || self.recycled.iter().any(|v| *v == ppn) {
+            panic!("Frame ppn={:#x} has not been allocated!", ppn);
+        }
+        // recycle
+        self.recycled.push(ppn);
+    }
+}
+
+type FrameAllocatorImpl = StackFrameAllocator;
+
+lazy_static! {
+    /// frame allocator instance through lazy_static!
+    pub static ref FRAME_ALLOCATOR: UPSafeCell<FrameAllocatorImpl> =
+        unsafe { UPSafeCell::new(FrameAllocatorImpl::new()) };
+}
+
+pub fn init_frame_allocator() {
+    extern "C" {
+        fn ekernel();
+    }
+    FRAME_ALLOCATOR.exclusive_access().init(
+        PhysAddr::from(ekernel as usize).ceil(),
+        PhysAddr::from(MEMORY_END).floor(),
+    );
+}
+
+/// initiate the frame allocator using `ekernel` and `MEMORY_END`
+pub fn frame_alloc() -> Option<FrameTracker> {
+    FRAME_ALLOCATOR
+        .exclusive_access()
+        .alloc()
+        .map(FrameTracker::new)
+}
+
+/// deallocate a frame
+pub fn frame_dealloc(ppn: PhysPageNum) {
+    FRAME_ALLOCATOR.exclusive_access().dealloc(ppn);
+}
+
+#[allow(unused)]
+/// a simple test for frame allocator
+pub fn frame_allocator_test() {
+    let mut v: Vec<FrameTracker> = Vec::new();
+    for i in 0..5 {
+        let frame = frame_alloc().unwrap();
+        info!("{:?}", frame);
+        v.push(frame);
+    }
+    v.clear();
+    for i in 0..5 {
+        let frame = frame_alloc().unwrap();
+        info!("{:?}", frame);
+        v.push(frame);
+    }
+    drop(v);
+    info!("frame_allocator_test passed!");
+}

os7-ref/src/mm/heap_allocator.rs

@@ -0,0 +1,51 @@
+//! The global allocator
+
+use crate::config::KERNEL_HEAP_SIZE;
+use buddy_system_allocator::LockedHeap;
+
+#[global_allocator]
+/// heap allocator instance
+static HEAP_ALLOCATOR: LockedHeap = LockedHeap::empty();
+
+#[alloc_error_handler]
+/// panic when heap allocation error occurs
+pub fn handle_alloc_error(layout: core::alloc::Layout) -> ! {
+    panic!("Heap allocation error, layout = {:?}", layout);
+}
+
+/// heap space ([u8; KERNEL_HEAP_SIZE])
+static mut HEAP_SPACE: [u8; KERNEL_HEAP_SIZE] = [0; KERNEL_HEAP_SIZE];
+
+/// initiate heap allocator
+pub fn init_heap() {
+    unsafe {
+        HEAP_ALLOCATOR
+            .lock()
+            .init(HEAP_SPACE.as_ptr() as usize, KERNEL_HEAP_SIZE);
+    }
+}
+
+#[allow(unused)]
+pub fn heap_test() {
+    use alloc::boxed::Box;
+    use alloc::vec::Vec;
+    extern "C" {
+        fn sbss();
+        fn ebss();
+    }
+    let bss_range = sbss as usize..ebss as usize;
+    let a = Box::new(5);
+    assert_eq!(*a, 5);
+    assert!(bss_range.contains(&(a.as_ref() as *const _ as usize)));
+    drop(a);
+    let mut v: Vec<usize> = Vec::new();
+    for i in 0..500 {
+        v.push(i);
+    }
+    for (i, vi) in v.iter().enumerate().take(500) {
+        assert_eq!(*vi, i);
+    }
+    assert!(bss_range.contains(&(v.as_ptr() as usize)));
+    drop(v);
+    info!("heap_test passed!");
+}

os7-ref/src/mm/memory_set.rs

@@ -0,0 +1,404 @@
+//! Implementation of [`MapArea`] and [`MemorySet`].
+
+use super::{frame_alloc, FrameTracker};
+use super::{PTEFlags, PageTable, PageTableEntry};
+use super::{PhysAddr, PhysPageNum, VirtAddr, VirtPageNum};
+use super::{StepByOne, VPNRange};
+use crate::config::{MEMORY_END, PAGE_SIZE, TRAMPOLINE, TRAP_CONTEXT, USER_STACK_SIZE, MMIO};
+use crate::sync::UPSafeCell;
+use alloc::collections::BTreeMap;
+use alloc::sync::Arc;
+use alloc::vec::Vec;
+use lazy_static::*;
+use riscv::register::satp;
+
+extern "C" {
+    fn stext();
+    fn etext();
+    fn srodata();
+    fn erodata();
+    fn sdata();
+    fn edata();
+    fn sbss_with_stack();
+    fn ebss();
+    fn ekernel();
+    fn strampoline();
+}
+
+lazy_static! {
+    /// a memory set instance through lazy_static! managing kernel space
+    pub static ref KERNEL_SPACE: Arc<UPSafeCell<MemorySet>> =
+        Arc::new(unsafe { UPSafeCell::new(MemorySet::new_kernel()) });
+}
+
+/// Get the token of the kernel memory space
+pub fn kernel_token() -> usize {
+    KERNEL_SPACE.exclusive_access().token()
+}
+
+/// memory set structure, controls virtual-memory space
+pub struct MemorySet {
+    page_table: PageTable,
+    areas: Vec<MapArea>,
+}
+
+impl MemorySet {
+    pub fn new_bare() -> Self {
+        Self {
+            page_table: PageTable::new(),
+            areas: Vec::new(),
+        }
+    }
+    pub fn token(&self) -> usize {
+        self.page_table.token()
+    }
+    /// Assume that no conflicts.
+    pub fn insert_framed_area(
+        &mut self,
+        start_va: VirtAddr,
+        end_va: VirtAddr,
+        permission: MapPermission,
+    ) {
+        self.push(
+            MapArea::new(start_va, end_va, MapType::Framed, permission),
+            None,
+        );
+    }
+    pub fn remove_area_with_start_vpn(&mut self, start_vpn: VirtPageNum) {
+        if let Some((idx, area)) = self
+            .areas
+            .iter_mut()
+            .enumerate()
+            .find(|(_, area)| area.vpn_range.get_start() == start_vpn)
+        {
+            area.unmap(&mut self.page_table);
+            self.areas.remove(idx);
+        }
+    }
+    fn push(&mut self, mut map_area: MapArea, data: Option<&[u8]>) {
+        map_area.map(&mut self.page_table);
+        if let Some(data) = data {
+            map_area.copy_data(&mut self.page_table, data);
+        }
+        self.areas.push(map_area);
+    }
+    /// Mention that trampoline is not collected by areas.
+    fn map_trampoline(&mut self) {
+        self.page_table.map(
+            VirtAddr::from(TRAMPOLINE).into(),
+            PhysAddr::from(strampoline as usize).into(),
+            PTEFlags::R | PTEFlags::X,
+        );
+    }
+    /// Without kernel stacks.
+    pub fn new_kernel() -> Self {
+        let mut memory_set = Self::new_bare();
+        // map trampoline
+        memory_set.map_trampoline();
+        // map kernel sections
+        info!(".text [{:#x}, {:#x})", stext as usize, etext as usize);
+        info!(".rodata [{:#x}, {:#x})", srodata as usize, erodata as usize);
+        info!(".data [{:#x}, {:#x})", sdata as usize, edata as usize);
+        info!(
+            ".bss [{:#x}, {:#x})",
+            sbss_with_stack as usize, ebss as usize
+        );
+        info!("mapping .text section");
+        memory_set.push(
+            MapArea::new(
+                (stext as usize).into(),
+                (etext as usize).into(),
+                MapType::Identical,
+                MapPermission::R | MapPermission::X,
+            ),
+            None,
+        );
+        info!("mapping .rodata section");
+        memory_set.push(
+            MapArea::new(
+                (srodata as usize).into(),
+                (erodata as usize).into(),
+                MapType::Identical,
+                MapPermission::R,
+            ),
+            None,
+        );
+        info!("mapping .data section");
+        memory_set.push(
+            MapArea::new(
+                (sdata as usize).into(),
+                (edata as usize).into(),
+                MapType::Identical,
+                MapPermission::R | MapPermission::W,
+            ),
+            None,
+        );
+        info!("mapping .bss section");
+        memory_set.push(
+            MapArea::new(
+                (sbss_with_stack as usize).into(),
+                (ebss as usize).into(),
+                MapType::Identical,
+                MapPermission::R | MapPermission::W,
+            ),
+            None,
+        );
+        info!("mapping physical memory");
+        memory_set.push(
+            MapArea::new(
+                (ekernel as usize).into(),
+                MEMORY_END.into(),
+                MapType::Identical,
+                MapPermission::R | MapPermission::W,
+            ),
+            None,
+        );
+        info!("mapping memory-mapped registers");
+        for pair in MMIO {
+            memory_set.push(
+                MapArea::new(
+                    (*pair).0.into(),
+                    ((*pair).0 + (*pair).1).into(),
+                    MapType::Identical,
+                    MapPermission::R | MapPermission::W,
+                ),
+            None);
+        }
+        memory_set
+    }
+    /// Include sections in elf and trampoline and TrapContext and user stack,
+    /// also returns user_sp and entry point.
+    pub fn from_elf(elf_data: &[u8]) -> (Self, usize, usize) {
+        let mut memory_set = Self::new_bare();
+        // map trampoline
+        memory_set.map_trampoline();
+        // map program headers of elf, with U flag
+        let elf = xmas_elf::ElfFile::new(elf_data).unwrap();
+        let elf_header = elf.header;
+        let magic = elf_header.pt1.magic;
+        assert_eq!(magic, [0x7f, 0x45, 0x4c, 0x46], "invalid elf!");
+        let ph_count = elf_header.pt2.ph_count();
+        let mut max_end_vpn = VirtPageNum(0);
+        for i in 0..ph_count {
+            let ph = elf.program_header(i).unwrap();
+            if ph.get_type().unwrap() == xmas_elf::program::Type::Load {
+                let start_va: VirtAddr = (ph.virtual_addr() as usize).into();
+                let end_va: VirtAddr = ((ph.virtual_addr() + ph.mem_size()) as usize).into();
+                let mut map_perm = MapPermission::U;
+                let ph_flags = ph.flags();
+                if ph_flags.is_read() {
+                    map_perm |= MapPermission::R;
+                }
+                if ph_flags.is_write() {
+                    map_perm |= MapPermission::W;
+                }
+                if ph_flags.is_execute() {
+                    map_perm |= MapPermission::X;
+                }
+                let map_area = MapArea::new(start_va, end_va, MapType::Framed, map_perm);
+                max_end_vpn = map_area.vpn_range.get_end();
+                memory_set.push(
+                    map_area,
+                    Some(&elf.input[ph.offset() as usize..(ph.offset() + ph.file_size()) as usize]),
+                );
+            }
+        }
+        // map user stack with U flags
+        let max_end_va: VirtAddr = max_end_vpn.into();
+        let mut user_stack_bottom: usize = max_end_va.into();
+        // guard page
+        user_stack_bottom += PAGE_SIZE;
+        let user_stack_top = user_stack_bottom + USER_STACK_SIZE;
+        memory_set.push(
+            MapArea::new(
+                user_stack_bottom.into(),
+                user_stack_top.into(),
+                MapType::Framed,
+                MapPermission::R | MapPermission::W | MapPermission::U,
+            ),
+            None,
+        );
+        // map TrapContext
+        memory_set.push(
+            MapArea::new(
+                TRAP_CONTEXT.into(),
+                TRAMPOLINE.into(),
+                MapType::Framed,
+                MapPermission::R | MapPermission::W,
+            ),
+            None,
+        );
+        (
+            memory_set,
+            user_stack_top,
+            elf.header.pt2.entry_point() as usize,
+        )
+    }
+    /// Copy an identical user_space
+    pub fn from_existed_user(user_space: &MemorySet) -> MemorySet {
+        let mut memory_set = Self::new_bare();
+        // map trampoline
+        memory_set.map_trampoline();
+        // copy data sections/trap_context/user_stack
+        for area in user_space.areas.iter() {
+            let new_area = MapArea::from_another(area);
+            memory_set.push(new_area, None);
+            // copy data from another space
+            for vpn in area.vpn_range {
+                let src_ppn = user_space.translate(vpn).unwrap().ppn();
+                let dst_ppn = memory_set.translate(vpn).unwrap().ppn();
+                dst_ppn
+                    .get_bytes_array()
+                    .copy_from_slice(src_ppn.get_bytes_array());
+            }
+        }
+        memory_set
+    }
+    pub fn activate(&self) {
+        let satp = self.page_table.token();
+        unsafe {
+            satp::write(satp);
+            core::arch::asm!("sfence.vma");
+        }
+    }
+    pub fn translate(&self, vpn: VirtPageNum) -> Option<PageTableEntry> {
+        self.page_table.translate(vpn)
+    }
+    pub fn recycle_data_pages(&mut self) {
+        //*self = Self::new_bare();
+        self.areas.clear();
+    }
+}
+
+/// map area structure, controls a contiguous piece of virtual memory
+pub struct MapArea {
+    vpn_range: VPNRange,
+    data_frames: BTreeMap<VirtPageNum, FrameTracker>,
+    map_type: MapType,
+    map_perm: MapPermission,
+}
+
+impl MapArea {
+    pub fn new(
+        start_va: VirtAddr,
+        end_va: VirtAddr,
+        map_type: MapType,
+        map_perm: MapPermission,
+    ) -> Self {
+        let start_vpn: VirtPageNum = start_va.floor();
+        let end_vpn: VirtPageNum = end_va.ceil();
+        Self {
+            vpn_range: VPNRange::new(start_vpn, end_vpn),
+            data_frames: BTreeMap::new(),
+            map_type,
+            map_perm,
+        }
+    }
+    pub fn from_another(another: &MapArea) -> Self {
+        Self {
+            vpn_range: VPNRange::new(another.vpn_range.get_start(), another.vpn_range.get_end()),
+            data_frames: BTreeMap::new(),
+            map_type: another.map_type,
+            map_perm: another.map_perm,
+        }
+    }
+    pub fn map_one(&mut self, page_table: &mut PageTable, vpn: VirtPageNum) {
+        let ppn: PhysPageNum;
+        match self.map_type {
+            MapType::Identical => {
+                ppn = PhysPageNum(vpn.0);
+            }
+            MapType::Framed => {
+                let frame = frame_alloc().unwrap();
+                ppn = frame.ppn;
+                self.data_frames.insert(vpn, frame);
+            }
+        }
+        let pte_flags = PTEFlags::from_bits(self.map_perm.bits).unwrap();
+        page_table.map(vpn, ppn, pte_flags);
+    }
+
+    pub fn unmap_one(&mut self, page_table: &mut PageTable, vpn: VirtPageNum) {
+        #[allow(clippy::single_match)]
+        match self.map_type {
+            MapType::Framed => {
+                self.data_frames.remove(&vpn);
+            }
+            _ => {}
+        }
+        page_table.unmap(vpn);
+    }
+    pub fn map(&mut self, page_table: &mut PageTable) {
+        for vpn in self.vpn_range {
+            self.map_one(page_table, vpn);
+        }
+    }
+    pub fn unmap(&mut self, page_table: &mut PageTable) {
+        for vpn in self.vpn_range {
+            self.unmap_one(page_table, vpn);
+        }
+    }
+    /// data: start-aligned but maybe with shorter length
+    /// assume that all frames were cleared before
+    pub fn copy_data(&mut self, page_table: &mut PageTable, data: &[u8]) {
+        assert_eq!(self.map_type, MapType::Framed);
+        let mut start: usize = 0;
+        let mut current_vpn = self.vpn_range.get_start();
+        let len = data.len();
+        loop {
+            let src = &data[start..len.min(start + PAGE_SIZE)];
+            let dst = &mut page_table
+                .translate(current_vpn)
+                .unwrap()
+                .ppn()
+                .get_bytes_array()[..src.len()];
+            dst.copy_from_slice(src);
+            start += PAGE_SIZE;
+            if start >= len {
+                break;
+            }
+            current_vpn.step();
+        }
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Debug)]
+/// map type for memory set: identical or framed
+pub enum MapType {
+    Identical,
+    Framed,
+}
+
+bitflags! {
+    /// map permission corresponding to that in pte: `R W X U`
+    pub struct MapPermission: u8 {
+        const R = 1 << 1;
+        const W = 1 << 2;
+        const X = 1 << 3;
+        const U = 1 << 4;
+    }
+}
+
+#[allow(unused)]
+pub fn remap_test() {
+    let mut kernel_space = KERNEL_SPACE.exclusive_access();
+    let mid_text: VirtAddr = ((stext as usize + etext as usize) / 2).into();
+    let mid_rodata: VirtAddr = ((srodata as usize + erodata as usize) / 2).into();
+    let mid_data: VirtAddr = ((sdata as usize + edata as usize) / 2).into();
+    assert!(!kernel_space
+        .page_table
+        .translate(mid_text.floor())
+        .unwrap()
+        .writable());
+    assert!(!kernel_space
+        .page_table
+        .translate(mid_rodata.floor())
+        .unwrap()
+        .writable());
+    assert!(!kernel_space
+        .page_table
+        .translate(mid_data.floor())
+        .unwrap()
+        .executable());
+    info!("remap_test passed!");
+}

os7-ref/src/mm/mod.rs

@@ -0,0 +1,29 @@
+//! Memory management implementation
+//!
+//! SV39 page-based virtual-memory architecture for RV64 systems, and
+//! everything about memory management, like frame allocator, page table,
+//! map area and memory set, is implemented here.
+//!
+//! Every task or process has a memory_set to control its virtual memory.
+
+
+mod address;
+mod frame_allocator;
+mod heap_allocator;
+mod memory_set;
+mod page_table;
+
+pub use address::{PhysAddr, PhysPageNum, VirtAddr, VirtPageNum};
+pub use address::{StepByOne, VPNRange};
+pub use frame_allocator::{frame_alloc, frame_dealloc, FrameTracker};
+pub use memory_set::{remap_test, kernel_token};
+pub use memory_set::{MapPermission, MemorySet, KERNEL_SPACE};
+pub use page_table::{translated_byte_buffer, translated_refmut, translated_ref, translated_str, PageTableEntry};
+pub use page_table::{PTEFlags, PageTable, UserBuffer};
+
+/// initiate heap allocator, frame allocator and kernel space
+pub fn init() {
+    heap_allocator::init_heap();
+    frame_allocator::init_frame_allocator();
+    KERNEL_SPACE.exclusive_access().activate();
+}

os7-ref/src/mm/page_table.rs

@@ -0,0 +1,260 @@
+//! Implementation of [`PageTableEntry`] and [`PageTable`].
+
+use super::{frame_alloc, FrameTracker, PhysAddr, PhysPageNum, StepByOne, VirtAddr, VirtPageNum};
+use alloc::string::String;
+use alloc::vec;
+use alloc::vec::Vec;
+use bitflags::*;
+
+bitflags! {
+    /// page table entry flags
+    pub struct PTEFlags: u8 {
+        const V = 1 << 0;
+        const R = 1 << 1;
+        const W = 1 << 2;
+        const X = 1 << 3;
+        const U = 1 << 4;
+        const G = 1 << 5;
+        const A = 1 << 6;
+        const D = 1 << 7;
+    }
+}
+
+#[derive(Copy, Clone)]
+#[repr(C)]
+/// page table entry structure
+pub struct PageTableEntry {
+    pub bits: usize,
+}
+
+impl PageTableEntry {
+    pub fn new(ppn: PhysPageNum, flags: PTEFlags) -> Self {
+        PageTableEntry {
+            bits: ppn.0 << 10 | flags.bits as usize,
+        }
+    }
+    pub fn empty() -> Self {
+        PageTableEntry { bits: 0 }
+    }
+    pub fn ppn(&self) -> PhysPageNum {
+        (self.bits >> 10 & ((1usize << 44) - 1)).into()
+    }
+    pub fn flags(&self) -> PTEFlags {
+        PTEFlags::from_bits(self.bits as u8).unwrap()
+    }
+    pub fn is_valid(&self) -> bool {
+        (self.flags() & PTEFlags::V) != PTEFlags::empty()
+    }
+    pub fn readable(&self) -> bool {
+        (self.flags() & PTEFlags::R) != PTEFlags::empty()
+    }
+    pub fn writable(&self) -> bool {
+        (self.flags() & PTEFlags::W) != PTEFlags::empty()
+    }
+    pub fn executable(&self) -> bool {
+        (self.flags() & PTEFlags::X) != PTEFlags::empty()
+    }
+}
+
+/// page table structure
+pub struct PageTable {
+    root_ppn: PhysPageNum,
+    frames: Vec<FrameTracker>,
+}
+
+/// Assume that it won't oom when creating/mapping.
+impl PageTable {
+    pub fn new() -> Self {
+        let frame = frame_alloc().unwrap();
+        PageTable {
+            root_ppn: frame.ppn,
+            frames: vec![frame],
+        }
+    }
+    /// Temporarily used to get arguments from user space.
+    pub fn from_token(satp: usize) -> Self {
+        Self {
+            root_ppn: PhysPageNum::from(satp & ((1usize << 44) - 1)),
+            frames: Vec::new(),
+        }
+    }
+    fn find_pte_create(&mut self, vpn: VirtPageNum) -> Option<&mut PageTableEntry> {
+        let mut idxs = vpn.indexes();
+        let mut ppn = self.root_ppn;
+        let mut result: Option<&mut PageTableEntry> = None;
+        for (i, idx) in idxs.iter_mut().enumerate() {
+            let pte = &mut ppn.get_pte_array()[*idx];
+            if i == 2 {
+                result = Some(pte);
+                break;
+            }
+            if !pte.is_valid() {
+                let frame = frame_alloc().unwrap();
+                *pte = PageTableEntry::new(frame.ppn, PTEFlags::V);
+                self.frames.push(frame);
+            }
+            ppn = pte.ppn();
+        }
+        result
+    }
+    fn find_pte(&self, vpn: VirtPageNum) -> Option<&PageTableEntry> {
+        let idxs = vpn.indexes();
+        let mut ppn = self.root_ppn;
+        let mut result: Option<&PageTableEntry> = None;
+        for (i, idx) in idxs.iter().enumerate() {
+            let pte = &ppn.get_pte_array()[*idx];
+            if i == 2 {
+                result = Some(pte);
+                break;
+            }
+            if !pte.is_valid() {
+                return None;
+            }
+            ppn = pte.ppn();
+        }
+        result
+    }
+    #[allow(unused)]
+    pub fn map(&mut self, vpn: VirtPageNum, ppn: PhysPageNum, flags: PTEFlags) {
+        let pte = self.find_pte_create(vpn).unwrap();
+        assert!(!pte.is_valid(), "vpn {:?} is mapped before mapping", vpn);
+        *pte = PageTableEntry::new(ppn, flags | PTEFlags::V);
+    }
+    #[allow(unused)]
+    pub fn unmap(&mut self, vpn: VirtPageNum) {
+        let pte = self.find_pte_create(vpn).unwrap();
+        assert!(pte.is_valid(), "vpn {:?} is invalid before unmapping", vpn);
+        *pte = PageTableEntry::empty();
+    }
+    pub fn translate(&self, vpn: VirtPageNum) -> Option<PageTableEntry> {
+        self.find_pte(vpn).copied()
+    }
+    pub fn translate_va(&self, va: VirtAddr) -> Option<PhysAddr> {
+        self.find_pte(va.clone().floor()).map(|pte| {
+            //println!("translate_va:va = {:?}", va);
+            let aligned_pa: PhysAddr = pte.ppn().into();
+            //println!("translate_va:pa_align = {:?}", aligned_pa);
+            let offset = va.page_offset();
+            let aligned_pa_usize: usize = aligned_pa.into();
+            (aligned_pa_usize + offset).into()
+        })
+    }
+    pub fn token(&self) -> usize {
+        8usize << 60 | self.root_ppn.0
+    }
+}
+
+/// translate a pointer to a mutable u8 Vec through page table
+pub fn translated_byte_buffer(token: usize, ptr: *const u8, len: usize) -> Vec<&'static mut [u8]> {
+    let page_table = PageTable::from_token(token);
+    let mut start = ptr as usize;
+    let end = start + len;
+    let mut v = Vec::new();
+    while start < end {
+        let start_va = VirtAddr::from(start);
+        let mut vpn = start_va.floor();
+        let ppn = page_table.translate(vpn).unwrap().ppn();
+        vpn.step();
+        let mut end_va: VirtAddr = vpn.into();
+        end_va = end_va.min(VirtAddr::from(end));
+        if end_va.page_offset() == 0 {
+            v.push(&mut ppn.get_bytes_array()[start_va.page_offset()..]);
+        } else {
+            v.push(&mut ppn.get_bytes_array()[start_va.page_offset()..end_va.page_offset()]);
+        }
+        start = end_va.into();
+    }
+    v
+}
+
+pub fn translated_str(token: usize, ptr: *const u8) -> String {
+    let page_table = PageTable::from_token(token);
+    let mut string = String::new();
+    let mut va = ptr as usize;
+    loop {
+        let ch: u8 = *(page_table
+            .translate_va(VirtAddr::from(va))
+            .unwrap()
+            .get_mut());
+        if ch == 0 {
+            break;
+        } else {
+            string.push(ch as char);
+            va += 1;
+        }
+    }
+    string
+}
+
+pub fn translated_ref<T>(token: usize, ptr: *const T) -> &'static T {
+    let page_table = PageTable::from_token(token);
+    page_table.translate_va(VirtAddr::from(ptr as usize)).unwrap().get_mut()
+}
+
+pub fn translated_refmut<T>(token: usize, ptr: *mut T) -> &'static mut T {
+    //println!("into translated_refmut!");
+    let page_table = PageTable::from_token(token);
+    let va = ptr as usize;
+    //println!("translated_refmut: before translate_va");
+    page_table
+        .translate_va(VirtAddr::from(va))
+        .unwrap()
+        .get_mut()
+}
+
+/// An abstraction over a buffer passed from user space to kernel space
+pub struct UserBuffer {
+    pub buffers: Vec<&'static mut [u8]>,
+}
+
+impl UserBuffer {
+    /// Constuct a UserBuffer
+    pub fn new(buffers: Vec<&'static mut [u8]>) -> Self {
+        Self { buffers }
+    }
+    /// Get the length of a UserBuffer
+    pub fn len(&self) -> usize {
+        let mut total: usize = 0;
+        for b in self.buffers.iter() {
+            total += b.len();
+        }
+        total
+    }
+}
+
+impl IntoIterator for UserBuffer {
+    type Item = *mut u8;
+    type IntoIter = UserBufferIterator;
+    fn into_iter(self) -> Self::IntoIter {
+        UserBufferIterator {
+            buffers: self.buffers,
+            current_buffer: 0,
+            current_idx: 0,
+        }
+    }
+}
+
+// An iterator over a UserBuffer
+pub struct UserBufferIterator {
+    buffers: Vec<&'static mut [u8]>,
+    current_buffer: usize,
+    current_idx: usize,
+}
+
+impl Iterator for UserBufferIterator {
+    type Item = *mut u8;
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current_buffer >= self.buffers.len() {
+            None
+        } else {
+            let r = &mut self.buffers[self.current_buffer][self.current_idx] as *mut _;
+            if self.current_idx + 1 == self.buffers[self.current_buffer].len() {
+                self.current_idx = 0;
+                self.current_buffer += 1;
+            } else {
+                self.current_idx += 1;
+            }
+            Some(r)
+        }
+    }
+}