add: memory area

os/Cargo.lock

@@ -8,6 +8,21 @@ version = "0.10.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dc827186963e592360843fb5ba4b973e145841266c1357f7180c43526f2e5b61"
 
+[[package]]
+name = "bitflags"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
+
+[[package]]
+name = "buddy_system_allocator"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4e85e760e105b46ae0bd1236578793c6c147ae7463fe95c8350296b8bfcb830"
+dependencies = [
+ "spin 0.7.1",
+]
+
 [[package]]
 name = "critical-section"
 version = "1.1.2"
@@ -30,7 +45,7 @@ version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 dependencies = [
- "spin",
+ "spin 0.9.8",
 ]
 
 [[package]]
@@ -52,6 +67,8 @@ checksum = "8d5439c4ad607c3c23abf66de8c8bf57ba8adcd1f129e699851a6e43935d339d"
 name = "os"
 version = "0.3.0"
 dependencies = [
+ "bitflags",
+ "buddy_system_allocator",
  "lazy_static",
  "riscv",
  "sbi-rt",
@@ -86,6 +103,12 @@ dependencies = [
  "static_assertions",
 ]
 
+[[package]]
+name = "spin"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13287b4da9d1207a4f4929ac390916d64eacfe236a487e9a9f5b3be392be5162"
+
 [[package]]
 name = "spin"
 version = "0.9.8"

os/Cargo.toml

@@ -7,3 +7,5 @@ edition = "2021"
 sbi-rt = { version = "0.0.2", features = ["legacy"] }
 lazy_static = { version = "1.4.0", features = ["spin_no_std"] }
 riscv = { version = "0.10.0" }
+buddy_system_allocator = {version = "0.6"}
+bitflags = {version = "2.6"}

os/src/boards/qemu.rs

@@ -1 +1,5 @@
 pub const CLOCK_FREQUENCY: usize = 10000000;
+pub const MEMORY_END: usize = 0x8800_0000;
+pub const MMIO: &[(usize, usize)] = &[
+    (0x0010_0000, 0x00_2000)
+];

os/src/config.rs

@@ -1,8 +1,17 @@
 pub const USER_STACK_SIZE: usize = 4096;
 pub const KERNEL_STACK_SIZE: usize = 4096 * 2;
+pub const KERNEL_HEAP_SIZE: usize = 0x30_0000;
+pub const PAGE_SIZE: usize = 0x1000;
+pub const PAGE_SIZE_BITS: usize = 0xc;
 
-pub const MAX_APP_NUM: usize = 4;
-pub const APP_BASE_ADDRESS: usize = 0x80400000;
-pub const APP_SIZE_LIMIT: usize = 0x20000;
+pub const TRAMPOLINE: usize = usize::MAX - PAGE_SIZE + 1;
+pub const TRAP_CONTEXT: usize = TRAMPOLINE - PAGE_SIZE;
 
-pub use crate::boards::qemu::CLOCK_FREQUENCY;
+/// Return (bottom, top) of a kernel stack in kernel space
+pub fn kernel_stack_position(app_id: usize) -> (usize, usize) {
+    let top = TRAMPOLINE - app_id * (KERNEL_STACK_SIZE + PAGE_SIZE);
+    let bottom = top - KERNEL_STACK_SIZE;
+    (bottom, top)
+}
+
+pub use crate::boards::qemu::{CLOCK_FREQUENCY, MEMORY_END, MMIO};

os/src/loader.rs

@@ -1,100 +0,0 @@
-use crate::config::{
-    APP_BASE_ADDRESS, APP_SIZE_LIMIT, KERNEL_STACK_SIZE, MAX_APP_NUM, USER_STACK_SIZE,
-};
-use crate::log_information;
-use crate::trap::context::TrapContext;
-use core::arch::asm;
-
-#[repr(align(4096))]
-#[derive(Copy, Clone)]
-struct KernelStack {
-    data: [u8; KERNEL_STACK_SIZE],
-}
-
-#[repr(align(4096))]
-#[derive(Copy, Clone)]
-struct UserStack {
-    data: [u8; USER_STACK_SIZE],
-}
-
-static KERNEL_STACK: [KernelStack; MAX_APP_NUM] = [KernelStack {
-    data: [0; KERNEL_STACK_SIZE],
-}; MAX_APP_NUM];
-
-static USER_STACK: [UserStack; MAX_APP_NUM] = [UserStack {
-    data: [0; USER_STACK_SIZE],
-}; MAX_APP_NUM];
-
-impl KernelStack {
-    fn get_sp(&self) -> usize {
-        self.data.as_ptr() as usize + KERNEL_STACK_SIZE
-    }
-
-    pub fn push_context(&self, trap_context: TrapContext) -> usize {
-        let pointer = (self.get_sp() - size_of::<TrapContext>()) as *mut TrapContext;
-
-        unsafe {
-            *pointer = trap_context;
-        }
-
-        pointer as usize
-    }
-}
-
-impl UserStack {
-    fn get_sp(&self) -> usize {
-        self.data.as_ptr() as usize + USER_STACK_SIZE
-    }
-}
-
-pub fn get_app_num() -> usize {
-    extern "C" {
-        fn _num_app();
-    }
-
-    let app_num_ptr = _num_app as usize as *const usize;
-
-    unsafe { app_num_ptr.read_volatile() }
-}
-
-pub fn load_apps() {
-    extern "C" {
-        fn _num_app();
-    }
-
-    let app_num_ptr = _num_app as usize as *const usize;
-    let app_num = unsafe { app_num_ptr.read_volatile() };
-    let app_start = unsafe { core::slice::from_raw_parts(app_num_ptr.add(1), app_num + 1) };
-
-    for i in 0..app_num {
-        let base_address = APP_BASE_ADDRESS + i * APP_SIZE_LIMIT;
-
-        // 清除目标的内存区域
-        for address in base_address..base_address + APP_SIZE_LIMIT {
-            unsafe {
-                (address as *mut u8).write_volatile(0);
-            }
-        }
-
-        // 将程序从数据段复制过来
-        let source = unsafe {
-            core::slice::from_raw_parts(app_start[i] as *const u8, app_start[i + 1] - app_start[i])
-        };
-        let destination =
-            unsafe { core::slice::from_raw_parts_mut(base_address as *mut u8, source.len()) };
-
-        destination.copy_from_slice(source);
-    }
-
-    log_information!("Load {} applications in memory.", app_num);
-    unsafe {
-        asm!("fence.i");
-    }
-}
-
-pub fn initialize_app_context(app_id: usize) -> usize {
-    KERNEL_STACK[app_id].push_context(TrapContext::init_application_context(
-        APP_BASE_ADDRESS + app_id * APP_SIZE_LIMIT,
-        USER_STACK[app_id].get_sp(),
-    ))
-}

os/src/main.rs

@@ -1,5 +1,7 @@
 #![no_std]
 #![no_main]
+#![feature(alloc_error_handler)]
+extern crate alloc;
 
 use crate::utils::clear_bss;
 use core::arch::global_asm;
@@ -7,7 +9,6 @@ use core::arch::global_asm;
 mod boards;
 mod config;
 mod console;
-mod loader;
 mod sbi;
 mod sync;
 mod syscall;
@@ -15,6 +16,7 @@ mod task;
 mod timer;
 mod trap;
 mod utils;
+mod memory;
 
 global_asm!(include_str!("entry.asm"));
 global_asm!(include_str!("link_app.asm"));
@@ -24,8 +26,6 @@ fn rust_main() -> ! {
     clear_bss();
     log_information!("Hello, rCore!");
     trap::init();
-    loader::load_apps();
-    task::run_first_task();
 
     unreachable!()
 }

os/src/memory.rs

@@ -0,0 +1,5 @@
+mod heap_allocator;
+mod address;
+mod page_table;
+mod frame_allocator;
+mod memory_set;

os/src/memory/address.rs

@@ -0,0 +1,256 @@
+use crate::config::{PAGE_SIZE, PAGE_SIZE_BITS};
+use core::fmt::{Debug, Formatter};
+use core::slice::from_raw_parts_mut;
+use crate::memory::page_table::PageTableEntry;
+
+// 在SV39模式下，物理地址的宽度为56，虚拟地址的宽度为39
+pub const PHYSICAL_ADDRESS_WIDTH: usize = 56;
+pub const PHYSICAL_PAGE_NUMBER_WIDTH: usize = PHYSICAL_ADDRESS_WIDTH - PAGE_SIZE_BITS;
+pub const VIRTUAL_ADDRESS_WIDTH: usize = 39;
+pub const VIRTUAL_PAGE_NUMBER_WIDTH: usize = VIRTUAL_ADDRESS_WIDTH - PAGE_SIZE_BITS;
+
+/// 物理地址
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub struct PhysicalAddress(pub usize);
+
+impl PhysicalAddress {
+    pub fn page_offset(&self) -> usize {
+        self.0 & (PAGE_SIZE - 1)
+    }
+
+    pub fn floor(&self) -> PhysicalPageNumber {
+        PhysicalPageNumber(self.0 / PAGE_SIZE)
+    }
+
+    pub fn ceil(&self) -> PhysicalPageNumber {
+        if self.0 == 0 {
+            PhysicalPageNumber(0)
+        } else {
+            PhysicalPageNumber((self.0 - 1 + PAGE_SIZE) / PAGE_SIZE)
+        }
+    }
+
+    pub fn is_aligned(&self) -> bool {
+        self.page_offset() == 0
+    }
+}
+
+impl Debug for PhysicalAddress {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        f.write_fmt(format_args!("Physical address: {:#x}.", self.0))
+    }
+}
+
+impl From<usize> for PhysicalAddress {
+    fn from(value: usize) -> Self {
+        Self(value & ((1 << PHYSICAL_ADDRESS_WIDTH) - 1))
+    }
+}
+
+impl From<PhysicalAddress> for usize {
+    fn from(value: PhysicalAddress) -> Self {
+        value.0
+    }
+}
+
+impl From<PhysicalAddress> for PhysicalPageNumber {
+    fn from(value: PhysicalAddress) -> Self {
+        assert_eq!(value.page_offset(), 0);
+        value.floor()
+    }
+}
+
+impl From<PhysicalPageNumber> for PhysicalAddress {
+    fn from(value: PhysicalPageNumber) -> Self {
+        Self(value.0 << PAGE_SIZE_BITS)
+    }
+}
+
+/// 物理页号
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub struct PhysicalPageNumber(pub usize);
+
+// 这里的unsafe只是为了绕过编译器的生命周期检查
+impl PhysicalPageNumber {
+    pub fn get_page_table_entry_array(&self) -> &'static mut [PageTableEntry] {
+        let address: PhysicalAddress = (*self).into();
+        unsafe {
+            // 一个页表的大小是2^12 byte
+            // 页表项的大小是8 byte
+            // 所有一共有2^9
+            from_raw_parts_mut(address.0 as *mut PageTableEntry, 512)
+        }
+    }
+
+    pub fn get_bytes_array(&self) -> &'static mut [u8] {
+        let address: PhysicalAddress = (*self).into();
+        unsafe {
+            from_raw_parts_mut(address.0 as *mut u8, PAGE_SIZE)
+        }
+    }
+
+    pub fn get_mut<T>(&self) ->&'static mut T {
+        let address: PhysicalAddress = (*self).into();
+        unsafe {
+            (address.0 as *mut T).as_mut().unwrap()
+        }
+    }
+}
+
+impl Debug for PhysicalPageNumber {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        f.write_fmt(format_args!("Physical page number: {:#x}.", self.0))
+    }
+}
+
+impl From<usize> for PhysicalPageNumber {
+    fn from(value: usize) -> Self {
+        Self(value & ((1 << PHYSICAL_PAGE_NUMBER_WIDTH) - 1))
+    }
+}
+
+impl From<PhysicalPageNumber> for usize {
+    fn from(value: PhysicalPageNumber) -> Self {
+        value.0
+    }
+}
+
+/// 虚拟地址
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub struct VirtualAddress(pub usize);
+
+impl VirtualAddress {
+    pub fn page_offset(&self) -> usize {
+        self.0 & (PAGE_SIZE - 1)
+    }
+    
+    pub fn is_aligned(&self) -> bool {
+        self.page_offset() == 0
+    }
+    
+    pub fn floor(&self) -> VirtualPageNumber {
+        VirtualPageNumber(self.0 / PAGE_SIZE)
+    }
+    
+    pub fn ceil(&self) -> VirtualPageNumber {
+        VirtualPageNumber((self.0 - 1 + PAGE_SIZE) / PAGE_SIZE)
+    }
+}
+
+impl Debug for VirtualAddress {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        f.write_fmt(format_args!("Virtual address: {:#x}.", self.0))
+    }
+}
+
+impl From<usize> for VirtualAddress {
+    fn from(value: usize) -> Self {
+        Self(value & ((1 << VIRTUAL_ADDRESS_WIDTH) - 1))
+    }
+}
+
+impl From<VirtualAddress> for usize {
+    fn from(value: VirtualAddress) -> Self {
+        value.0
+    }
+}
+
+/// 虚拟页号
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub struct VirtualPageNumber(pub usize);
+
+impl VirtualPageNumber {
+    pub fn get_indexes(&self) -> [usize; 3] {
+        let mut number = self.0;
+        let mut indexes = [0usize; 3];
+
+        for i in 0..3 {
+            indexes[i] = number & (1 << 9 - 1);
+            number = number >> 9;
+        }
+
+        indexes
+    }
+    
+    pub fn step(&mut self) {
+        self.0 += 1;
+    }
+}
+
+impl Debug for VirtualPageNumber {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        f.write_fmt(format_args!("Virtual page number: {:#x}.", self.0))
+    }
+}
+
+impl From<usize> for VirtualPageNumber {
+    fn from(value: usize) -> Self {
+        Self(value & ((1 << VIRTUAL_PAGE_NUMBER_WIDTH) - 1))
+    }
+}
+
+impl From<VirtualPageNumber> for usize {
+    fn from(value: VirtualPageNumber) -> Self {
+        value.0
+    }
+}
+
+#[derive(Copy, Clone)]
+pub struct VirtualPageSpan {
+    left: VirtualPageNumber,
+    right: VirtualPageNumber
+}
+
+impl VirtualPageSpan {
+    pub fn new(start: VirtualPageNumber, end: VirtualPageNumber) -> Self {
+        Self {
+            left: start,
+            right: end
+        }
+    }
+    
+    pub fn get_start(&self) -> VirtualPageNumber {
+        self.left
+    }
+    
+    pub fn get_end(&self) -> VirtualPageNumber {
+        self.right
+    }
+}
+
+impl IntoIterator for VirtualPageSpan {
+    type Item = VirtualPageNumber;
+    type IntoIter = VirtualPageSpanIterator;
+
+    fn into_iter(self) -> Self::IntoIter {
+        VirtualPageSpanIterator::new(&self)
+    }
+}
+
+pub struct VirtualPageSpanIterator {
+    current: VirtualPageNumber,
+    end: VirtualPageNumber
+}
+
+impl VirtualPageSpanIterator {
+    fn new(span: &VirtualPageSpan) -> Self {
+        Self {
+            current: span.left,
+            end: span.right
+        }
+    }
+}
+
+impl Iterator for VirtualPageSpanIterator {
+    type Item = VirtualPageNumber;
+    
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current == self.end {
+            None
+        } else { 
+            let t = self.current;
+            self.current.step();
+            Some(t)
+        }
+    }
+}

os/src/memory/frame_allocator.rs

@@ -0,0 +1,110 @@
+use crate::config::MEMORY_END;
+use crate::memory::address::{PhysicalAddress, PhysicalPageNumber};
+use crate::sync::single_cell::SingleCell;
+use alloc::vec;
+use alloc::vec::Vec;
+use lazy_static::lazy_static;
+
+trait FrameAllocator {
+    fn new() -> Self;
+
+    fn alloc(&mut self) -> Option<PhysicalPageNumber>;
+
+    fn dealloc(&mut self, page_number: PhysicalPageNumber);
+}
+
+struct StackedFrameAllocator {
+    current: usize,
+    end: usize,
+    recycled: Vec<usize>,
+}
+
+impl FrameAllocator for StackedFrameAllocator {
+    fn new() -> Self {
+        Self {
+            current: 0,
+            end: 0,
+            recycled: vec![],
+        }
+    }
+
+    fn alloc(&mut self) -> Option<PhysicalPageNumber> {
+        if let Some(page_num) = self.recycled.pop() {
+            Some(page_num.into())
+        } else {
+            if self.current == self.end {
+                None
+            } else {
+                self.current += 1;
+                Some((self.current - 1).into())
+            }
+        }
+    }
+
+    fn dealloc(&mut self, page_number: PhysicalPageNumber) {
+        let page_number = page_number.0;
+
+        if page_number >= self.current
+            || self.recycled.iter().find(|&p| *p == page_number).is_some()
+        {
+            panic!(
+                "Frame physical page number={:#x} has not been allocated.",
+                page_number
+            );
+        }
+
+        self.recycled.push(page_number);
+    }
+}
+
+impl StackedFrameAllocator {
+    pub fn init(&mut self, l: PhysicalPageNumber, r: PhysicalPageNumber) {
+        self.current = l.0;
+        self.end = r.0;
+    }
+}
+
+pub struct FrameTracker {
+    pub page_number: PhysicalPageNumber
+}
+
+impl FrameTracker {
+    fn new(page_number: PhysicalPageNumber) -> Self {
+        // 清空页帧中的内容
+        let byte_array = page_number.get_bytes_array();
+        for i in byte_array.as_mut() {
+            *i = 0;
+        }
+        
+        Self {
+            page_number
+        }
+    }
+}
+
+impl Drop for FrameTracker {
+    fn drop(&mut self) {
+        FRAME_ALLOCATOR.exclusive_borrow().dealloc(self.page_number);
+    }
+}
+
+lazy_static! {
+    static ref FRAME_ALLOCATOR: SingleCell<StackedFrameAllocator> =
+        SingleCell::new(StackedFrameAllocator::new());
+}
+
+pub fn initialize_frame_allocator() {
+    extern "C" {
+        fn ekernel();
+    }
+
+    FRAME_ALLOCATOR.exclusive_borrow().init(
+        PhysicalAddress::from(ekernel as usize).ceil(),
+        PhysicalAddress::from(MEMORY_END).floor(),
+    )
+}       
+
+pub fn allocate_frame() -> Option<FrameTracker> {
+    FRAME_ALLOCATOR.exclusive_borrow().alloc().map(|p| FrameTracker::new(p))
+}
+

os/src/memory/heap_allocator.rs

@@ -0,0 +1,20 @@
+use buddy_system_allocator::LockedHeap;
+use crate::config::KERNEL_HEAP_SIZE;
+
+#[global_allocator]
+static HEAP_ALLOCATOR: LockedHeap = LockedHeap::empty();
+
+static mut HEAP_SPACE: [u8; KERNEL_HEAP_SIZE] = [0; KERNEL_HEAP_SIZE];
+
+pub fn init_heap() {
+    unsafe {
+        HEAP_ALLOCATOR
+            .lock()
+            .init(HEAP_SPACE.as_ptr() as usize, KERNEL_HEAP_SIZE);
+    }
+}
+
+#[alloc_error_handler]
+pub fn handle_alloc_error(layout: core::alloc::Layout) -> ! {
+    panic!("Heap allocation failed, layout: {:?}", layout);
+}

os/src/memory/memory_set.rs

@@ -0,0 +1,145 @@
+use alloc::collections::BTreeMap;
+use alloc::vec;
+use alloc::vec::Vec;
+use bitflags::bitflags;
+use crate::config::PAGE_SIZE;
+use crate::memory::address::{PhysicalPageNumber, VirtualAddress, VirtualPageNumber, VirtualPageSpan};
+use crate::memory::frame_allocator::{allocate_frame, FrameTracker};
+use crate::memory::page_table::{PageTable, PageTableEntryFlags};
+
+/// 虚拟地址的映射方式
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+pub enum MapType {
+    /// 恒等映射
+    Identical,
+    /// 新分配物理页帧
+    Framed
+}
+
+bitflags! {
+    /// 逻辑段的权限控制
+    /// 只是PageTableEntryFlags的子集
+    /// 其他的标志位对于权限控制无用，只和地址转换有关
+    pub struct MapPermission: u8 {
+        const R = 1 << 1;
+        const W = 1 << 2;
+        const X = 1 << 3;
+        const U = 1 << 4;
+    }
+}
+
+/// 一段地址连续的虚拟内存
+pub struct MapArea {
+    virtual_page_span: VirtualPageSpan,
+    data_frames: BTreeMap<VirtualPageNumber, FrameTracker>,
+    map_type: MapType,
+    map_permission: MapPermission
+}
+
+impl MapArea {
+    pub fn new(
+        start: VirtualAddress,
+        end: VirtualAddress,
+        map_type: MapType,
+        map_permission: MapPermission
+    ) -> Self {
+        let start = start.floor();
+        let end = end.ceil();
+        
+        Self {
+            virtual_page_span: VirtualPageSpan::new(start, end),
+            data_frames: BTreeMap::new(),
+            map_type,
+            map_permission
+        }
+    }
+    
+    pub fn map(&mut self, page_table: &mut PageTable) {
+        for page_number in self.virtual_page_span {
+            self.map_one(page_table, page_number);
+        }
+    }
+    
+    pub fn unmap(&mut self, page_table: &mut PageTable) {
+        for page_number in self.virtual_page_span {
+            self.unmap_one(page_table, page_number);
+        }
+    }
+    
+    /// Copy data into this MapArea
+    /// The data is start-aligned and shorter than MapArea!
+    pub fn copy_data(&mut self, page_table: &mut PageTable, data: &[u8]) {
+        assert_eq!(self.map_type, MapType::Framed);
+        let mut start = 0;
+        let mut current_page_number = self.virtual_page_span.get_start();
+        let length = data.len();
+
+        loop {
+            let source = &data[start..length.min(start + PAGE_SIZE)];
+            let destination = &mut page_table
+                .translate(current_page_number)
+                .unwrap()
+                .physical_page_numer()
+                .get_bytes_array()[..source.len()];
+            
+            destination.copy_from_slice(source);
+            start += PAGE_SIZE;
+            if start >= length {
+                break
+            }
+            
+            // 自增
+            current_page_number.step()
+        }
+    }
+    
+    fn map_one(&mut self, page_table: &mut PageTable, virtual_page_number: VirtualPageNumber) {
+        let physical_page_number = match self.map_type {
+            MapType::Identical => {
+                // 使用和虚拟页号一样的物理页号
+                PhysicalPageNumber(virtual_page_number.0)
+            },
+            MapType::Framed => {
+                // 分配新的物理页帧
+                let frame = allocate_frame().unwrap();
+                let frame_number = frame.page_number;
+                self.data_frames.insert(virtual_page_number, frame);
+                frame_number
+            }
+        };
+        let flags = PageTableEntryFlags::from_bits(self.map_permission.bits()).unwrap();
+        page_table.map(virtual_page_number, physical_page_number, flags);
+    }
+    
+    fn unmap_one(&mut self, page_table: &mut PageTable, virtual_page_number: VirtualPageNumber) {
+        match self.map_type {
+            MapType::Framed => {
+                self.data_frames.remove(&virtual_page_number);
+            },
+            _ => {}
+        }
+        page_table.unmap(virtual_page_number);
+    }
+}
+
+pub struct MemorySet {
+    page_table: PageTable,
+    areas: Vec<MapArea>
+}
+
+impl MemorySet {
+    pub fn new_bare() -> Self {
+        Self {
+            page_table: PageTable::new(),
+            areas: vec![]
+        }
+    }
+    
+    fn push(&mut self, mut map_area: MapArea, data: Option<&[u8]>) {
+        
+    }
+}
+
+
+
+

os/src/memory/page_table.rs

@@ -0,0 +1,161 @@
+use crate::memory::address::{PhysicalPageNumber, VirtualPageNumber, PHYSICAL_PAGE_NUMBER_WIDTH};
+use crate::memory::frame_allocator::{allocate_frame, FrameTracker};
+use alloc::vec;
+use alloc::vec::Vec;
+use bitflags::bitflags;
+
+bitflags! {
+    #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+    pub struct PageTableEntryFlags: u8 {
+        /// Valid
+        const V = 1 << 0;
+        ///Read
+        const R = 1 << 1;
+        /// Write
+        const W = 1 << 2;
+        /// Execute
+        const X = 1 << 3;
+        /// User
+        const U = 1 << 4;
+        /// unknown
+        const G = 1 << 5;
+        /// Accessed
+        const A = 1 << 6;
+        /// Dirty
+        const D = 1 << 7;
+    }
+}
+
+#[derive(Copy, Clone)]
+#[repr(C)]
+pub struct PageTableEntry {
+    pub bits: usize,
+}
+
+impl PageTableEntry {
+    pub fn new(page_num: PhysicalPageNumber, flags: PageTableEntryFlags) -> Self {
+        Self {
+            bits: page_num.0 << 10 | flags.bits() as usize,
+        }
+    }
+
+    pub fn empty() -> Self {
+        Self { bits: 0 }
+    }
+
+    pub fn physical_page_numer(&self) -> PhysicalPageNumber {
+        (self.bits >> 10 & (1usize << PHYSICAL_PAGE_NUMBER_WIDTH - 1)).into()
+    }
+
+    pub fn flags(&self) -> PageTableEntryFlags {
+        PageTableEntryFlags::from_bits(self.bits as u8).unwrap()
+    }
+
+    pub fn is_valid(&self) -> bool {
+        (self.flags() & PageTableEntryFlags::V) != PageTableEntryFlags::empty()
+    }
+
+    pub fn readable(&self) -> bool {
+        (self.flags() & PageTableEntryFlags::R) != PageTableEntryFlags::empty()
+    }
+
+    pub fn writable(&self) -> bool {
+        (self.flags() & PageTableEntryFlags::W) != PageTableEntryFlags::empty()
+    }
+
+    pub fn executable(&self) -> bool {
+        (self.flags() & PageTableEntryFlags::X) != PageTableEntryFlags::empty()
+    }
+}
+
+pub struct PageTable {
+    root_page_number: PhysicalPageNumber,
+    frames: Vec<FrameTracker>,
+}
+
+impl PageTable {
+    pub fn new() -> Self {
+        let frame = allocate_frame().unwrap();
+        Self {
+            root_page_number: frame.page_number,
+            frames: vec![frame],
+        }
+    }
+
+    pub fn map(
+        &mut self,
+        virtual_page_number: VirtualPageNumber,
+        physical_page_number: PhysicalPageNumber,
+        flags: PageTableEntryFlags,
+    ) {
+        let entry = self.find_entry_or_create(virtual_page_number);
+        assert!(
+            !entry.is_valid(),
+            "Virtual page number {:?} is mapped before mapping.",
+            virtual_page_number
+        );
+        *entry = PageTableEntry::new(physical_page_number, flags | PageTableEntryFlags::V);
+    }
+
+    pub fn unmap(&mut self, virtual_page_number: VirtualPageNumber) {
+        let entry = self.find_entry(virtual_page_number).unwrap();
+        assert!(
+            entry.is_valid(),
+            "Virtual page number {:?} is invalid before unmapping",
+            virtual_page_number
+        );
+        *entry = PageTableEntry::empty();
+    }
+
+    /// 从satp寄存器创建临时的页表
+    /// 方便在用户空间时手动查看页表
+    pub fn from_token(satp: usize) -> Self {
+        Self {
+            root_page_number: PhysicalPageNumber::from(
+                satp & ((1usize << PHYSICAL_PAGE_NUMBER_WIDTH) - 1),
+            ),
+            frames: vec![],
+        }
+    }
+
+    pub fn translate(&self, virtual_page_number: VirtualPageNumber) -> Option<PageTableEntry> {
+        self.find_entry(virtual_page_number).map(|e| e.clone())
+    }
+
+    fn find_entry_or_create(&mut self, page_number: VirtualPageNumber) -> &mut PageTableEntry {
+        let indexes = page_number.get_indexes();
+        let mut physical_page_number = self.root_page_number;
+
+        for i in 0..2 {
+            let entry = &mut physical_page_number.get_page_table_entry_array()[indexes[i]];
+
+            // 当V是1，其他都是0的页帧就是页表
+            if !entry.is_valid() {
+                let frame = allocate_frame().unwrap();
+                *entry = PageTableEntry::new(frame.page_number, PageTableEntryFlags::V);
+                self.frames.push(frame);
+            }
+
+            physical_page_number = entry.physical_page_numer();
+        }
+
+        &mut physical_page_number.get_page_table_entry_array()[indexes[2]]
+    }
+
+    fn find_entry(&self, page_number: VirtualPageNumber) -> Option<&mut PageTableEntry> {
+        let indexes = page_number.get_indexes();
+        let mut physical_page_number = self.root_page_number;
+
+        for i in 0..2 {
+            let entry = &mut physical_page_number.get_page_table_entry_array()[indexes[i]];
+
+            if !entry.is_valid() {
+                return None;
+            }
+
+            physical_page_number = entry.physical_page_numer();
+        }
+
+        Some(&mut physical_page_number.get_page_table_entry_array()[indexes[2]])
+    }
+}

os/src/task.rs

@@ -1,7 +1,5 @@
 use lazy_static::lazy_static;
 
-use crate::config::MAX_APP_NUM;
-use crate::loader::{get_app_num, initialize_app_context};
 use crate::log_information;
 use crate::sbi::shutdown;
 use crate::sync::single_cell::SingleCell;

user/Makefile

@@ -0,0 +1,23 @@
+TARGET := riscv64gc-unknown-none-elf
+MODE := release
+APP_DIR := src/bin
+TARGET_DIR := target/$(TARGET)/$(MODE)
+APPS := $(wildcard $(APP_DIR)/*.rs)
+ELFS := $(patsubst $(APP_DIR)/%.rs, $(TARGET_DIR)/%, $(APPS))
+BINS := $(patsubst $(APP_DIR)/%.rs, $(TARGET_DIR)/%.bin, $(APPS))
+
+OBJDUMP := rust-objdump --arch-name=riscv64
+OBJCOPY := rust-objcopy --binary-architecture=riscv64
+
+elf: $(APPS)
+	@cargo build --release
+
+binary: elf
+	@$(foreach elf, $(ELFS), $(OBJCOPY) $(elf) --strip-all -O binary $(patsubst $(TARGET_DIR)/%, $(TARGET_DIR)/%.bin, $(elf));)
+
+build: binary
+
+clean:
+	@cargo clean
+
+.PHONY: elf binary build clean

user/build.py

@@ -1,30 +0,0 @@
-#!/bin/python3
-import os
-
-base_address = 0x80400000
-step = 0x20000
-linker = 'src/linker.ld'
-target_dir = "target/riscv64gc-unknown-none-elf/release/"
-
-app_id = 0
-apps = os.listdir('src/bin')
-apps.sort()
-for app in apps:
-    app = app[:app.find('.')]
-    lines = []
-    lines_before = []
-    with open(linker, 'r') as f:
-        for line in f.readlines():
-            lines_before.append(line)
-            line = line.replace(hex(base_address), hex(base_address+step * app_id))
-            lines.append(line)
-    with open(linker, 'w+') as f:
-        f.writelines(lines)
-    os.system('cargo build --bin %s --release' % app)
-    source_name = target_dir + app
-    dest_name = target_dir + app + ".bin"
-    os.system("rust-objcopy %s --binary-architecture=riscv64 --strip-all -O binary %s" %(source_name, dest_name))
-    print('[build.py] application %s start with address %s' %(app, hex(base_address+step*app_id)))
-    with open(linker, 'w+') as f:
-        f.writelines(lines_before)
-    app_id = app_id + 1

user/src/bin/load_fault.rs

@@ -0,0 +1,17 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+use core::ptr::{null_mut, read_volatile};
+
+#[no_mangle]
+fn main() -> i32 {
+    println!("Application 'load_fault' is running...");
+    println!("Kernel should kill this application!");
+    unsafe {
+        let _ = read_volatile(null_mut::<u8>());
+    }
+    0
+}

user/src/bin/set_break.rs

@@ -0,0 +1,56 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+use core::ptr::slice_from_raw_parts_mut;
+use user_lib::sys_set_break;
+
+#[no_mangle]
+fn main() -> i32 {
+    println!("Test set break start...");
+    const PAGE_SIZE: usize = 0x1000;
+    
+    let origin_break = sys_set_break(0);
+    println!("Origin break address is {:x}.", origin_break);
+    
+    let break_address = sys_set_break(PAGE_SIZE as i32);
+    if origin_break != break_address {
+        return -1;
+    }
+    
+    let break_address = sys_set_break(0);
+    println!("Now break address is {:x}.", break_address);
+    
+    println!("Try to write into allocated page.");
+    let new_page = unsafe {
+        &mut *slice_from_raw_parts_mut(origin_break as usize as *const u8 as *mut u8, PAGE_SIZE)
+    };
+    for pos in 0..PAGE_SIZE {
+        new_page[pos] = 0;
+    }
+    println!("Write successfully.");
+    
+    sys_set_break(PAGE_SIZE as i32 * 10);
+    let break_address = sys_set_break(0);
+    println!("Allocated 10 more pages, break address is {:x}.", break_address);
+    
+    sys_set_break(PAGE_SIZE as i32 * -11);
+    let break_address = sys_set_break(0);
+    println!("Deallocated all 11 pages, break address is {:x}.", break_address);
+    
+    println!("Try to deallocated one more page, which should fail.");
+    let result = sys_set_break(PAGE_SIZE as i32 * -1);
+    if result == -1 {
+        println!("But succeed, exit!");
+        return -1;
+    }
+    
+    println!("Try to write into deallocated pages, which should make this application killed by kernel.");
+    for pos in 0..PAGE_SIZE {
+        new_page[pos] = 0;
+    }
+    
+    0
+}

user/src/lib.rs

@@ -11,7 +11,6 @@ pub mod console;
 #[no_mangle]
 #[link_section = ".text.entry"]
 pub extern "C" fn _start() -> ! {
-    utils::clear_bss();
     exit(main());
     panic!("Unreachable after exit main!");
 }
@@ -36,3 +35,7 @@ pub fn get_time() -> isize {
 pub fn sys_yield() -> isize {
     syscall::sys_yield()
 }
+
+pub fn sys_set_break(size: i32) -> isize {
+    syscall::sys_set_break(size)
+}

user/src/linker.ld

@@ -1,7 +1,7 @@
 OUTPUT_ARCH(riscv)
 ENTRY(_start)
 
-BASE_ADDRESS = 0x80400000;
+BASE_ADDRESS = 0x10000;
 
 SECTIONS
 {
@@ -10,19 +10,19 @@ SECTIONS
         *(.text.entry)
         *(.text .text.*)
     }
+    . = ALIGN(4K);
     .rodata : {
         *(.rodata .rodata.*)
         *(.srodata .srodata.*)
     }
+    . = ALIGN(4K);
     .data : {
         *(.data .data.*)
         *(.sdata .sdata.*)
     }
     .bss : {
-        start_bss = .;
         *(.bss .bss.*)
         *(.sbss .sbss.*)
-        end_bss = .;
     }
     /DISCARD/ : {
         *(.eh_frame)

user/src/syscall.rs

@@ -4,6 +4,7 @@ const SYSCALL_WRITE: usize = 64;
 const SYSCALL_EXIT: usize = 93;
 const SYSCALL_YIELD: usize = 124;
 const SYSCALL_GET_TIME: usize = 169;
+const SYSCALL_SET_BREAK: usize = 214;
 
 fn syscall(id: usize, args: [usize; 3]) -> isize {
     let mut result: isize;
@@ -36,3 +37,7 @@ pub fn sys_yield() -> isize {
 pub fn sys_get_time() -> isize {
     syscall(SYSCALL_GET_TIME, [0, 0, 0])
 }
+
+pub fn sys_set_break(size: i32) -> isize {
+    syscall(SYSCALL_SET_BREAK, [size as usize, 0, 0])
+}

user/src/utils.rs

@@ -1,18 +1,6 @@
 use crate::println;
 use core::panic::PanicInfo;
 
-pub fn clear_bss() {
-    extern "C" {
-        fn start_bss();
-
-        fn end_bss();
-    }
-
-    for i in start_bss as usize..end_bss as usize {
-        unsafe { (i as *mut u8).write_volatile(0) }
-    }
-}
-
 #[panic_handler]
 fn panic_handler(info: &PanicInfo) -> ! {
     let message = info.message();