Paging Implementation

This commit is contained in:
Sainnhe Park 2022-01-13 12:09:37 +08:00
parent c3e1897c23
commit 042405c597
4 changed files with 102 additions and 17 deletions

View File

@ -13,7 +13,7 @@ edition = "2021"
# panic = "abort" # 禁用 panic 时的栈展开 # panic = "abort" # 禁用 panic 时的栈展开
[dependencies] [dependencies]
bootloader = "0.9.20" bootloader = { version = "0.9.20", features = ["map_physical_memory"] }
volatile = "0.2.6" volatile = "0.2.6"
spin = "0.5.2" spin = "0.5.2"
x86_64 = "0.14.7" x86_64 = "0.14.7"

View File

@ -10,6 +10,7 @@ pub mod serial;
pub mod vga_buffer; pub mod vga_buffer;
pub mod interrupts; pub mod interrupts;
pub mod gdt; pub mod gdt;
pub mod memory;
pub trait Testable { pub trait Testable {
fn run(&self) -> (); fn run(&self) -> ();
@ -42,8 +43,13 @@ pub fn test_panic_handler(info: &PanicInfo) -> ! {
} }
#[cfg(test)] #[cfg(test)]
#[no_mangle] use bootloader::{entry_point, BootInfo};
pub extern "C" fn _start() -> ! {
#[cfg(test)]
entry_point!(test_kernel_main);
#[cfg(test)]
fn test_kernel_main(_boot_info: &'static BootInfo) -> ! {
init(); init();
test_main(); test_main();
hlt_loop(); hlt_loop();

View File

@ -6,25 +6,26 @@
use core::panic::PanicInfo; use core::panic::PanicInfo;
use anos::println; use anos::println;
use bootloader::{BootInfo, entry_point};
entry_point!(kernel_main);
fn kernel_main(boot_info: &'static BootInfo) -> ! {
use anos::memory::{ self, BootInfoFrameAllocator };
use x86_64::{ structures::paging::Page, VirtAddr };
#[no_mangle] // 不重整函数名,否则编译器可能会生成名为 _ZN3blog_os4_start7hb173fedf945531caE 的函数
// extern "C" 告诉编译器这个函数应当使用 C 语言的调用约定
// 函数名为 _start 是因为大多数系统默认用这个名字作为入口点名称
// -> ! 代表这是一个发散函数,不允许有任何返回值,因为它不会被任何函数调用,而是将直接被 bootloader 调用
pub extern "C" fn _start() -> ! {
println!("Hello World{}", "!"); println!("Hello World{}", "!");
anos::init(); anos::init();
let ptr = 0x2031b2 as *mut u32; let phys_mem_offset = VirtAddr::new(boot_info.physical_memory_offset);
unsafe { let x = *ptr; } let mut mapper = unsafe { memory::init(phys_mem_offset) };
println!("read worked"); let mut frame_allocator = unsafe { BootInfoFrameAllocator::init(&boot_info.memory_map) };
unsafe { *ptr = 42 };
println!("write worked");
use x86_64::registers::control::Cr3; let page = Page::containing_address(VirtAddr::new(0xdeadbeaf000));
let (level_4_page_table, _) = Cr3::read(); memory::create_example_mapping(page, &mut mapper, &mut frame_allocator);
println!("Level 4 page table at: {:?}", level_4_page_table.start_address());
let page_ptr: *mut u64 = page.start_address().as_mut_ptr();
unsafe { page_ptr.offset(400).write_volatile(0x_f021_f077_f065_f04e)};
// 触发一个中断 // 触发一个中断
x86_64::instructions::interrupts::int3(); x86_64::instructions::interrupts::int3();

78
src/memory.rs Normal file
View File

@ -0,0 +1,78 @@
use bootloader::bootinfo::{MemoryMap, MemoryRegionType};
use x86_64::{
structures::paging::{
FrameAllocator, Mapper, OffsetPageTable, Page, PageTable, PhysFrame, Size4KiB,
},
PhysAddr, VirtAddr,
};
pub unsafe fn init(physical_memory_offset: VirtAddr) -> OffsetPageTable<'static> {
let level_4_table = active_level_4_table(physical_memory_offset);
OffsetPageTable::new(level_4_table, physical_memory_offset)
}
unsafe fn active_level_4_table(physical_memory_offset: VirtAddr) -> &'static mut PageTable {
use x86_64::registers::control::Cr3;
let (level_4_table_frame, _) = Cr3::read();
let phys = level_4_table_frame.start_address();
let virt = physical_memory_offset + phys.as_u64();
let page_table_ptr: *mut PageTable = virt.as_mut_ptr();
&mut *page_table_ptr
}
pub fn create_example_mapping(
page: Page,
mapper: &mut OffsetPageTable,
frame_allocator: &mut impl FrameAllocator<Size4KiB>,
) {
use x86_64::structures::paging::PageTableFlags as Flags;
let frame = PhysFrame::containing_address(PhysAddr::new(0xb8000));
let flags = Flags::PRESENT | Flags::WRITABLE;
let map_to_result = unsafe {
mapper.map_to(page, frame, flags, frame_allocator)
};
map_to_result.expect("map_to failed").flush();
}
pub struct EmptyFrameAllocator;
unsafe impl FrameAllocator<Size4KiB> for EmptyFrameAllocator {
fn allocate_frame(&mut self) -> Option<PhysFrame> {
None
}
}
pub struct BootInfoFrameAllocator {
memory_map: &'static MemoryMap,
next: usize,
}
impl BootInfoFrameAllocator {
pub unsafe fn init(memory_map: &'static MemoryMap) -> Self {
BootInfoFrameAllocator {
memory_map,
next: 0,
}
}
fn usable_frames(&self) -> impl Iterator<Item = PhysFrame> {
let regions = self.memory_map.iter();
let usable_regions = regions.filter(|r| r.region_type == MemoryRegionType::Usable);
let addr_ranges = usable_regions.map(|r| r.range.start_addr()..r.range.end_addr());
let frame_addresses = addr_ranges.flat_map(|r| r.step_by(4096));
frame_addresses.map(|addr| PhysFrame::containing_address(PhysAddr::new(addr)))
}
}
unsafe impl FrameAllocator<Size4KiB> for BootInfoFrameAllocator {
fn allocate_frame(&mut self) -> Option<PhysFrame> {
let frame = self.usable_frames().nth(self.next);
self.next += 1;
frame
}
}