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Delete our memory::translate_addr function again

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Philipp Oppermann
2019-03-13 14:12:56 +01:00
parent cb4410c84e
commit b0e1527a95
1 changed files with 1 additions and 51 deletions
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52
src/memory.rs
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@@ -1,6 +1,6 @@
use x86_64::{ use x86_64::{
structures::paging::{MappedPageTable, MapperAllSizes, PageTable, PhysFrame}, structures::paging::{MappedPageTable, MapperAllSizes, PageTable, PhysFrame},
PhysAddr, VirtAddr, VirtAddr,
}; };
/// Initialize a new MappedPageTable. /// Initialize a new MappedPageTable.
@@ -36,53 +36,3 @@ unsafe fn active_level_4_table(physical_memory_offset: u64) -> &'static mut Page
&mut *page_table_ptr // unsafe &mut *page_table_ptr // unsafe
} }
/// Translates the given virtual address to the mapped physical address, or
/// `None` if the address is not mapped.
///
/// This function is unsafe because the caller must guarantee that the
/// complete physical memory is mapped to virtual memory at the passed
/// `physical_memory_offset`.
pub unsafe fn translate_addr(addr: VirtAddr, physical_memory_offset: u64) -> Option<PhysAddr> {
translate_addr_inner(addr, physical_memory_offset)
}
/// Private function that is called by `translate_addr`.
///
/// This function is safe to limit the scope of `unsafe` because Rust treats
/// the whole body of unsafe functions as an unsafe block. This function must
/// only be reachable through `unsafe fn` from outside of this module.
fn translate_addr_inner(addr: VirtAddr, physical_memory_offset: u64) -> Option<PhysAddr> {
use x86_64::registers::control::Cr3;
use x86_64::structures::paging::page_table::FrameError;
// read the active level 4 frame from the CR3 register
let (level_4_table_frame, _) = Cr3::read();
let table_indexes = [
addr.p4_index(),
addr.p3_index(),
addr.p2_index(),
addr.p1_index(),
];
let mut frame = level_4_table_frame;
// traverse the multi-level page table
for &index in &table_indexes {
// convert the frame into a page table reference
let virt = frame.start_address().as_u64() + physical_memory_offset;
let table_ptr: *const PageTable = VirtAddr::new(virt).as_ptr();
let table = unsafe { &*table_ptr };
// read the page table entry and update `frame`
let entry = &table[index];
frame = match entry.frame() {
Ok(frame) => frame,
Err(FrameError::FrameNotPresent) => return None,
Err(FrameError::HugeFrame) => panic!("huge pages not supported"),
};
}
// calculate the physical address by adding the page offset
Some(frame.start_address() + u64::from(addr.page_offset()))
}