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Add unsafe map_to function and make translate unsafe, too

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These functions are unsafe because it's possible to get aliased &mut references.
This commit is contained in:
Philipp Oppermann
2015-12-09 00:51:34 +01:00
parent e84344f59a
commit 46b93e0650
2 changed files with 33 additions and 4 deletions
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20
src/memory/paging/mod.rs
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@@ -1,4 +1,5 @@
use memory::{PAGE_SIZE, Frame};
pub use self::entry::*;
use memory::{PAGE_SIZE, Frame, FrameAllocator};
mod entry;
mod table;
@@ -38,14 +39,13 @@ impl Page {
}
}
pub fn translate(virtual_address: VirtualAddress) -> Option<PhysicalAddress> {
pub unsafe fn translate(virtual_address: VirtualAddress) -> Option<PhysicalAddress> {
let offset = virtual_address % PAGE_SIZE;
translate_page(Page::containing_address(virtual_address))
.map(|frame| frame.number * PAGE_SIZE + offset)
}
fn translate_page(page: Page) -> Option<Frame> {
use self::entry::HUGE_PAGE;
unsafe fn translate_page(page: Page) -> Option<Frame> {
let p3 = unsafe { &*table::P4 }.next_table(page.p4_index());
@@ -83,3 +83,15 @@ fn translate_page(page: Page) -> Option<Frame> {
.and_then(|p1| p1[page.p1_index()].pointed_frame())
.or_else(huge_page)
}
pub unsafe fn map_to<A>(page: Page, frame: Frame, flags: EntryFlags, allocator: &mut A)
where A: FrameAllocator
{
let p4 = unsafe { &mut *table::P4 };
let mut p3 = p4.next_table_create(page.p4_index(), allocator);
let mut p2 = p3.next_table_create(page.p3_index(), allocator);
let mut p1 = p2.next_table_create(page.p2_index(), allocator);
assert!(p1[page.p1_index()].is_unused());
p1[page.p1_index()].set(frame, flags | PRESENT);
}