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+
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};
+use crate::sync::UPSafeCell;
+use alloc::collections::BTreeMap;
+use alloc::sync::Arc;
+use alloc::vec::Vec;
+use core::arch::asm;
+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! {
+ pub static ref KERNEL_SPACE: Arc<UPSafeCell<MemorySet>> =
+ Arc::new(unsafe { UPSafeCell::new(MemorySet::new_kernel()) });
+}
+
+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()
+ }
+
+ 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);
+ }
+
+ fn map_trampoline(&mut self) {
+ self.page_table.map(
+ VirtAddr::from(TRAMPOLINE).into(),
+ PhysAddr::from(strampoline as usize).into(),
+ PTEFlags::R | PTEFlags::X,
+ );
+ }
+
+ pub fn new_kernel() -> Self {
+ let mut memory_set = Self::new_bare();
+
+ memory_set.map_trampoline();
+
+ println!(".text [{:#x}, {:#x})", stext as usize, etext as usize);
+ println!(".rodata [{:#x}, {:#x})", srodata as usize, erodata as usize);
+ println!(".data [{:#x}, {:#x})", sdata as usize, edata as usize);
+ println!(
+ ".bss [{:#x}, {:#x})",
+ sbss_with_stack as usize, ebss as usize
+ );
+ println!("mapping .text section");
+ memory_set.push(
+ MapArea::new(
+ (stext as usize).into(),
+ (etext as usize).into(),
+ MapType::Identical,
+ MapPermission::R | MapPermission::X,
+ ),
+ None,
+ );
+ println!("mapping .rodata section");
+ memory_set.push(
+ MapArea::new(
+ (srodata as usize).into(),
+ (erodata as usize).into(),
+ MapType::Identical,
+ MapPermission::R,
+ ),
+ None,
+ );
+ println!("mapping .data section");
+ memory_set.push(
+ MapArea::new(
+ (sdata as usize).into(),
+ (edata as usize).into(),
+ MapType::Identical,
+ MapPermission::R | MapPermission::W,
+ ),
+ None,
+ );
+ println!("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,
+ );
+ println!("mapping physical memory");
+ memory_set.push(
+ MapArea::new(
+ (ekernel as usize).into(),
+ MEMORY_END.into(),
+ MapType::Identical,
+ MapPermission::R | MapPermission::W,
+ ),
+ None,
+ );
+ memory_set
+ }
+
+
+ pub fn from_elf(elf_data: &[u8]) -> (Self, usize, usize) {
+ let mut memory_set = Self::new_bare();
+
+ memory_set.map_trampoline();
+
+ 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]),
+ );
+ }
+ }
+
+ let max_end_va: VirtAddr = max_end_vpn.into();
+ let mut user_stack_bottom: usize = max_end_va.into();
+
+ 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,
+ );
+
+ 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,
+ )
+ }
+ pub fn from_existed_user(user_space: &MemorySet) -> MemorySet {
+ let mut memory_set = Self::new_bare();
+
+ memory_set.map_trampoline();
+
+ for area in user_space.areas.iter() {
+ let new_area = MapArea::from_another(area);
+ memory_set.push(new_area, None);
+
+ 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);
+ asm!("sfence.vma");
+ }
+ }
+ pub fn translate(&self, vpn: VirtPageNum) -> Option<PageTableEntry> {
+ self.page_table.translate(vpn)
+ }
+ pub fn recycle_data_pages(&mut self) {
+
+ self.areas.clear();
+ }
+}
+
+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) {
+ if 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);
+ }
+ }
+
+
+ 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)]
+pub enum MapType {
+ Identical,
+ Framed,
+}
+
+bitflags! {
+ 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(),
+ );
+ println!("remap_test passed!");
+}
+
