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::EntryFlags,
23 PageTableKind, VirtAddr,
24 };
25
26 /// 用于存储重映射页表的位图和页面
27 pub static EARLY_IOREMAP_PAGES: SpinLock<EarlyIoRemapPages> =
28 SpinLock::new(EarlyIoRemapPages::new());
29
30 /// 早期重映射使用的页表
31 #[repr(C)]
32 #[repr(align(4096))]
33 #[derive(Clone, Copy)]
34 struct EarlyRemapPage {
35 data: [u64; MMArch::PAGE_SIZE],
36 }
37
38 impl EarlyRemapPage {
39 /// 清空数据
zero(&mut self)40 fn zero(&mut self) {
41 self.data.fill(0);
42 }
43 }
44
45 #[repr(C)]
46 pub struct EarlyIoRemapPages {
47 pages: [EarlyRemapPage; Self::EARLY_REMAP_PAGES_NUM],
48 bmp: StaticBitmap<{ Self::EARLY_REMAP_PAGES_NUM }>,
49 }
50
51 impl EarlyIoRemapPages {
52 /// 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
53 pub const EARLY_REMAP_PAGES_NUM: usize = 256;
new() -> Self54 pub const fn new() -> Self {
55 Self {
56 pages: [EarlyRemapPage {
57 data: [0; MMArch::PAGE_SIZE],
58 }; Self::EARLY_REMAP_PAGES_NUM],
59 bmp: StaticBitmap::new(),
60 }
61 }
62
63 /// 分配一个页面
64 ///
65 /// 如果成功，返回虚拟地址
66 ///
67 /// 如果失败，返回None
allocate_page(&mut self) -> Option<VirtAddr>68 pub fn allocate_page(&mut self) -> Option<VirtAddr> {
69 if let Some(index) = self.bmp.first_false_index() {
70 self.bmp.set(index, true);
71 // 清空数据
72 self.pages[index].zero();
73
74 let p = &self.pages[index] as *const EarlyRemapPage as usize;
75 let vaddr = VirtAddr::new(p);
76 assert!(vaddr.check_aligned(MMArch::PAGE_SIZE));
77 return Some(vaddr);
78 } else {
79 return None;
80 }
81 }
82
free_page(&mut self, addr: VirtAddr)83 pub fn free_page(&mut self, addr: VirtAddr) {
84 // 判断地址是否合法
85 let start_vaddr = &self.pages[0] as *const EarlyRemapPage as usize;
86 let offset = addr.data() - start_vaddr;
87 let index = offset / MMArch::PAGE_SIZE;
88 if index < Self::EARLY_REMAP_PAGES_NUM {
89 assert!(self.bmp.get(index).unwrap());
90 self.bmp.set(index, false);
91 }
92 }
93 }
94
95 /// 伪分配器
96 struct PseudoAllocator<MMA> {
97 phantom: PhantomData<MMA>,
98 }
99
100 impl<MMA: MemoryManagementArch> PseudoAllocator<MMA> {
new() -> Self101 pub const fn new() -> Self {
102 Self {
103 phantom: PhantomData,
104 }
105 }
106 }
107
108 /// 为NoInitAllocator实现FrameAllocator
109 impl<MMA: MemoryManagementArch> FrameAllocator for PseudoAllocator<MMA> {
allocate(&mut self, count: PageFrameCount) -> Option<(PhysAddr, PageFrameCount)>110 unsafe fn allocate(&mut self, count: PageFrameCount) -> Option<(PhysAddr, PageFrameCount)> {
111 assert!(count.data() == 1);
112 let vaddr = EARLY_IOREMAP_PAGES.lock_irqsave().allocate_page()?;
113 let paddr = MMA::virt_2_phys(vaddr)?;
114 return Some((paddr, count));
115 }
116
free(&mut self, address: PhysAddr, count: PageFrameCount)117 unsafe fn free(&mut self, address: PhysAddr, count: PageFrameCount) {
118 assert_eq!(count.data(), 1);
119 assert!(address.check_aligned(MMA::PAGE_SIZE));
120
121 let vaddr = MMA::phys_2_virt(address);
122 if let Some(vaddr) = vaddr {
123 EARLY_IOREMAP_PAGES.lock_irqsave().free_page(vaddr);
124 }
125 }
126 /// @brief: 获取内存区域页帧的使用情况
127 /// @param self
128 /// @return 页帧的使用情况
usage(&self) -> PageFrameUsage129 unsafe fn usage(&self) -> PageFrameUsage {
130 // 暂时不支持
131 panic!("NoInitAllocator can't get page frame usage");
132 }
133 }
134
135 /// Use pseudo mapper to map physical memory to virtual memory.
136 ///
137 /// ## Safety
138 ///
139 /// 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
140 ///
141 /// 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）
142 #[inline(never)]
pseudo_map_phys(vaddr: VirtAddr, paddr: PhysAddr, count: PageFrameCount)143 pub unsafe fn pseudo_map_phys(vaddr: VirtAddr, paddr: PhysAddr, count: PageFrameCount) {
144 let flags: EntryFlags<MMArch> = EntryFlags::new().set_write(true);
145
146 pseudo_map_phys_with_flags(vaddr, paddr, count, flags);
147 }
148
149 /// Use pseudo mapper to map physical memory to virtual memory
150 /// with READ_ONLY and EXECUTE flags.
151 #[inline(never)]
pseudo_map_phys_ro(vaddr: VirtAddr, paddr: PhysAddr, count: PageFrameCount)152 pub unsafe fn pseudo_map_phys_ro(vaddr: VirtAddr, paddr: PhysAddr, count: PageFrameCount) {
153 let flags: EntryFlags<MMArch> = EntryFlags::new().set_write(false).set_execute(true);
154
155 pseudo_map_phys_with_flags(vaddr, paddr, count, flags);
156 }
157
158 #[inline(never)]
pseudo_map_phys_with_flags( vaddr: VirtAddr, paddr: PhysAddr, count: PageFrameCount, flags: EntryFlags<MMArch>, )159 pub unsafe fn pseudo_map_phys_with_flags(
160 vaddr: VirtAddr,
161 paddr: PhysAddr,
162 count: PageFrameCount,
163 flags: EntryFlags<MMArch>,
164 ) {
165 assert!(vaddr.check_aligned(MMArch::PAGE_SIZE));
166 assert!(paddr.check_aligned(MMArch::PAGE_SIZE));
167
168 let mut pseudo_allocator = PseudoAllocator::<MMArch>::new();
169
170 let mut mapper = crate::mm::page::PageMapper::<MMArch, _>::new(
171 PageTableKind::Kernel,
172 MMArch::table(PageTableKind::Kernel),
173 &mut pseudo_allocator,
174 );
175
176 for i in 0..count.data() {
177 let vaddr = vaddr + i * MMArch::PAGE_SIZE;
178 let paddr = paddr + i * MMArch::PAGE_SIZE;
179 let flusher: crate::mm::page::PageFlush<MMArch> =
180 mapper.map_phys(vaddr, paddr, flags).unwrap();
181 flusher.ignore();
182 }
183
184 mapper.make_current();
185 }
186
187 /// Unmap physical memory from virtual memory.
188 ///
189 /// ## 说明
190 ///
191 /// 该函数在系统启动早期，内存管理尚未初始化的时候使用
192 #[inline(never)]
pseudo_unmap_phys(vaddr: VirtAddr, count: PageFrameCount)193 pub unsafe fn pseudo_unmap_phys(vaddr: VirtAddr, count: PageFrameCount) {
194 assert!(vaddr.check_aligned(MMArch::PAGE_SIZE));
195
196 let mut pseudo_allocator = PseudoAllocator::<MMArch>::new();
197
198 let mut mapper = crate::mm::page::PageMapper::<MMArch, _>::new(
199 PageTableKind::Kernel,
200 MMArch::table(PageTableKind::Kernel),
201 &mut pseudo_allocator,
202 );
203
204 for i in 0..count.data() {
205 let vaddr = vaddr + i * MMArch::PAGE_SIZE;
206 if let Some((_, _, flusher)) = mapper.unmap_phys(vaddr, true) {
207 flusher.ignore();
208 };
209 }
210
211 mapper.make_current();
212 }
213