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https://github.com/DragonOS-Community/DragonOS.git
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163 lines
5.1 KiB
Rust
163 lines
5.1 KiB
Rust
//! 该文件用于系统启动早期,内存管理器初始化之前,提供一些简单的内存映射功能
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//!
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//! 映射关系为:
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//!
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//! 虚拟地址 0-100M与虚拟地址 0x8000_0000_0000 - 0x8000_0640_0000 之间具有重映射关系。
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//! 也就是说,他们的第二级页表在最顶级页表中,占用了第0和第256个页表项。
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//!
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//! 对于x86:
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//! 这里假设在内核引导文件中,已经填写了前100M的页表,其中,前50M是真实映射到内存的,后面的仅仅创建了页表,表项全部为0。
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use bitmap::{traits::BitMapOps, StaticBitmap};
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use crate::{
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libs::spinlock::SpinLock,
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mm::{MMArch, MemoryManagementArch, PhysAddr},
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};
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use core::marker::PhantomData;
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use super::{
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allocator::page_frame::{FrameAllocator, PageFrameCount, PageFrameUsage},
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page::PageFlags,
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PageTableKind, VirtAddr,
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};
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/// 用于存储重映射页表的位图和页面
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static EARLY_IOREMAP_PAGES: SpinLock<EarlyIoRemapPages> = SpinLock::new(EarlyIoRemapPages::new());
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/// 早期重映射使用的页表
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#[repr(C)]
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#[repr(align(4096))]
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#[derive(Clone, Copy)]
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struct EarlyRemapPage {
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data: [u64; MMArch::PAGE_SIZE],
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}
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impl EarlyRemapPage {
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/// 清空数据
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fn zero(&mut self) {
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self.data.fill(0);
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}
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}
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#[repr(C)]
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struct EarlyIoRemapPages {
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pages: [EarlyRemapPage; Self::EARLY_REMAP_PAGES_NUM],
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bmp: StaticBitmap<{ Self::EARLY_REMAP_PAGES_NUM }>,
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}
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impl EarlyIoRemapPages {
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/// 预留的用于在内存管理初始化之前,映射内存所使用的页表数量
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pub const EARLY_REMAP_PAGES_NUM: usize = 256;
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pub const fn new() -> Self {
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Self {
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pages: [EarlyRemapPage {
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data: [0; MMArch::PAGE_SIZE],
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}; Self::EARLY_REMAP_PAGES_NUM],
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bmp: StaticBitmap::new(),
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}
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}
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/// 分配一个页面
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///
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/// 如果成功,返回虚拟地址
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///
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/// 如果失败,返回None
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pub fn allocate_page(&mut self) -> Option<VirtAddr> {
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if let Some(index) = self.bmp.first_false_index() {
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self.bmp.set(index, true);
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// 清空数据
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self.pages[index].zero();
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let p = &self.pages[index] as *const EarlyRemapPage as usize;
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let vaddr = VirtAddr::new(p);
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assert!(vaddr.check_aligned(MMArch::PAGE_SIZE));
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return Some(vaddr);
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} else {
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return None;
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}
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}
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pub fn free_page(&mut self, addr: VirtAddr) {
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// 判断地址是否合法
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let start_vaddr = &self.pages[0] as *const EarlyRemapPage as usize;
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let offset = addr.data() - start_vaddr;
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let index = offset / MMArch::PAGE_SIZE;
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if index < Self::EARLY_REMAP_PAGES_NUM {
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assert_eq!(self.bmp.get(index).unwrap(), true);
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self.bmp.set(index, false);
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}
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}
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}
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/// 伪分配器
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struct PseudoAllocator<MMA> {
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phantom: PhantomData<MMA>,
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}
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impl<MMA: MemoryManagementArch> PseudoAllocator<MMA> {
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pub const fn new() -> Self {
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Self {
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phantom: PhantomData,
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}
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}
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}
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/// 为NoInitAllocator实现FrameAllocator
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impl<MMA: MemoryManagementArch> FrameAllocator for PseudoAllocator<MMA> {
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unsafe fn allocate(&mut self, count: PageFrameCount) -> Option<(PhysAddr, PageFrameCount)> {
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assert!(count.data() == 1);
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let vaddr = EARLY_IOREMAP_PAGES.lock_irqsave().allocate_page()?;
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let paddr = MMA::virt_2_phys(vaddr)?;
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return Some((paddr, count));
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}
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unsafe fn free(&mut self, address: PhysAddr, count: PageFrameCount) {
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assert_eq!(count.data(), 1);
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assert!(address.check_aligned(MMA::PAGE_SIZE));
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let vaddr = MMA::phys_2_virt(address);
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if let Some(vaddr) = vaddr {
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EARLY_IOREMAP_PAGES.lock_irqsave().free_page(vaddr);
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}
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}
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/// @brief: 获取内存区域页帧的使用情况
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/// @param self
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/// @return 页帧的使用情况
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unsafe fn usage(&self) -> PageFrameUsage {
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// 暂时不支持
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panic!("NoInitAllocator can't get page frame usage");
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}
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}
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/// Use pseudo mapper to map physical memory to virtual memory.
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///
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/// ## Safety
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///
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/// 调用该函数时,必须保证内存管理器尚未初始化。否则将导致未定义的行为
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///
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/// 并且,内核引导文件必须以4K页为粒度,填写了前100M的内存映射关系。(具体以本文件开头的注释为准)
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pub unsafe fn pseudo_map_phys(vaddr: VirtAddr, paddr: PhysAddr, count: PageFrameCount) {
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assert!(vaddr.check_aligned(MMArch::PAGE_SIZE));
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assert!(paddr.check_aligned(MMArch::PAGE_SIZE));
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let mut pseudo_allocator = PseudoAllocator::<MMArch>::new();
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let mut mapper = crate::mm::page::PageMapper::<MMArch, _>::new(
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PageTableKind::Kernel,
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MMArch::table(PageTableKind::Kernel),
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&mut pseudo_allocator,
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);
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let flags: PageFlags<MMArch> = PageFlags::new().set_write(true).set_execute(true);
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for i in 0..count.data() {
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let vaddr = vaddr + i * MMArch::PAGE_SIZE;
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let paddr = paddr + i * MMArch::PAGE_SIZE;
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let flusher = mapper.map_phys(vaddr, paddr, flags).unwrap();
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flusher.ignore();
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}
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mapper.make_current();
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}
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