1 //! 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 2 //! 3 //! 映射关系为： 4 //! 5 //! 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。 6 //! 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。 7 //! 8 //! 对于x86: 9 //! 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。 10 11 use bitmap::{traits::BitMapOps, StaticBitmap}; 12 13 use crate::{ 14 libs::spinlock::SpinLock, 15 mm::{MMArch, MemoryManagementArch, PhysAddr}, 16 }; 17 18 use core::marker::PhantomData; 19 20 use super::{ 21 allocator::page_frame::{FrameAllocator, PageFrameCount, PageFrameUsage}, 22 page::PageFlags, 23 PageTableKind, VirtAddr, 24 }; 25 26 /// 用于存储重映射页表的位图和页面 27 static EARLY_IOREMAP_PAGES: SpinLock<EarlyIoRemapPages> = SpinLock::new(EarlyIoRemapPages::new()); 28 29 /// 早期重映射使用的页表 30 #[repr(C)] 31 #[repr(align(4096))] 32 #[derive(Clone, Copy)] 33 struct EarlyRemapPage { 34 data: [u64; MMArch::PAGE_SIZE], 35 } 36 37 impl EarlyRemapPage { 38 /// 清空数据 39 fn zero(&mut self) { 40 self.data.fill(0); 41 } 42 } 43 44 #[repr(C)] 45 struct EarlyIoRemapPages { 46 pages: [EarlyRemapPage; Self::EARLY_REMAP_PAGES_NUM], 47 bmp: StaticBitmap<{ Self::EARLY_REMAP_PAGES_NUM }>, 48 } 49 50 impl EarlyIoRemapPages { 51 /// 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 52 pub const EARLY_REMAP_PAGES_NUM: usize = 256; 53 pub const fn new() -> Self { 54 Self { 55 pages: [EarlyRemapPage { 56 data: [0; MMArch::PAGE_SIZE], 57 }; Self::EARLY_REMAP_PAGES_NUM], 58 bmp: StaticBitmap::new(), 59 } 60 } 61 62 /// 分配一个页面 63 /// 64 /// 如果成功，返回虚拟地址 65 /// 66 /// 如果失败，返回None 67 pub fn allocate_page(&mut self) -> Option<VirtAddr> { 68 if let Some(index) = self.bmp.first_false_index() { 69 self.bmp.set(index, true); 70 // 清空数据 71 self.pages[index].zero(); 72 73 let p = &self.pages[index] as *const EarlyRemapPage as usize; 74 let vaddr = VirtAddr::new(p); 75 assert!(vaddr.check_aligned(MMArch::PAGE_SIZE)); 76 return Some(vaddr); 77 } else { 78 return None; 79 } 80 } 81 82 pub fn free_page(&mut self, addr: VirtAddr) { 83 // 判断地址是否合法 84 let start_vaddr = &self.pages[0] as *const EarlyRemapPage as usize; 85 let offset = addr.data() - start_vaddr; 86 let index = offset / MMArch::PAGE_SIZE; 87 if index < Self::EARLY_REMAP_PAGES_NUM { 88 assert_eq!(self.bmp.get(index).unwrap(), true); 89 self.bmp.set(index, false); 90 } 91 } 92 } 93 94 /// 伪分配器 95 struct PseudoAllocator<MMA> { 96 phantom: PhantomData<MMA>, 97 } 98 99 impl<MMA: MemoryManagementArch> PseudoAllocator<MMA> { 100 pub const fn new() -> Self { 101 Self { 102 phantom: PhantomData, 103 } 104 } 105 } 106 107 /// 为NoInitAllocator实现FrameAllocator 108 impl<MMA: MemoryManagementArch> FrameAllocator for PseudoAllocator<MMA> { 109 unsafe fn allocate(&mut self, count: PageFrameCount) -> Option<(PhysAddr, PageFrameCount)> { 110 assert!(count.data() == 1); 111 let vaddr = EARLY_IOREMAP_PAGES.lock_irqsave().allocate_page()?; 112 let paddr = MMA::virt_2_phys(vaddr)?; 113 return Some((paddr, count)); 114 } 115 116 unsafe fn free(&mut self, address: PhysAddr, count: PageFrameCount) { 117 assert_eq!(count.data(), 1); 118 assert!(address.check_aligned(MMA::PAGE_SIZE)); 119 let vaddr = MMA::phys_2_virt(address); 120 if let Some(vaddr) = vaddr { 121 EARLY_IOREMAP_PAGES.lock_irqsave().free_page(vaddr); 122 } 123 } 124 /// @brief: 获取内存区域页帧的使用情况 125 /// @param self 126 /// @return 页帧的使用情况 127 unsafe fn usage(&self) -> PageFrameUsage { 128 // 暂时不支持 129 panic!("NoInitAllocator can't get page frame usage"); 130 } 131 } 132 133 /// Use pseudo mapper to map physical memory to virtual memory. 134 /// 135 /// ## Safety 136 /// 137 /// 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 138 /// 139 /// 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） 140 #[inline(never)] 141 pub unsafe fn pseudo_map_phys(vaddr: VirtAddr, paddr: PhysAddr, count: PageFrameCount) { 142 assert!(vaddr.check_aligned(MMArch::PAGE_SIZE)); 143 assert!(paddr.check_aligned(MMArch::PAGE_SIZE)); 144 145 let mut pseudo_allocator = PseudoAllocator::<MMArch>::new(); 146 147 let mut mapper = crate::mm::page::PageMapper::<MMArch, _>::new( 148 PageTableKind::Kernel, 149 MMArch::table(PageTableKind::Kernel), 150 &mut pseudo_allocator, 151 ); 152 153 let flags: PageFlags<MMArch> = PageFlags::new().set_write(true).set_execute(true); 154 155 for i in 0..count.data() { 156 let vaddr = vaddr + i * MMArch::PAGE_SIZE; 157 let paddr = paddr + i * MMArch::PAGE_SIZE; 158 let flusher = mapper.map_phys(vaddr, paddr, flags).unwrap(); 159 flusher.ignore(); 160 } 161 162 mapper.make_current(); 163 } 164 165 /// Unmap physical memory from virtual memory. 166 /// 167 /// ## 说明 168 /// 169 /// 该函数在系统启动早期，内存管理尚未初始化的时候使用 170 #[inline(never)] 171 pub unsafe fn pseudo_unmap_phys(vaddr: VirtAddr, count: PageFrameCount) { 172 assert!(vaddr.check_aligned(MMArch::PAGE_SIZE)); 173 assert!(count.data() == 1); 174 175 let mut pseudo_allocator = PseudoAllocator::<MMArch>::new(); 176 177 let mut mapper = crate::mm::page::PageMapper::<MMArch, _>::new( 178 PageTableKind::Kernel, 179 MMArch::table(PageTableKind::Kernel), 180 &mut pseudo_allocator, 181 ); 182 183 for i in 0..count.data() { 184 let vaddr = vaddr + i * MMArch::PAGE_SIZE; 185 mapper.unmap_phys(vaddr, true).map(|(_, _, flusher)| { 186 flusher.ignore(); 187 }); 188 } 189 190 mapper.make_current(); 191 } 192