Paging: Rework identity_map

src/arch/x86_64/kernel/acpi.rs

+use x86_64::structures::paging::PhysFrame;
+
 use crate::arch::x86_64::kernel::processor;
 use crate::arch::x86_64::mm::paging::{
 	BasePageSize, PageSize, PageTableEntryFlags, PageTableEntryFlagsExt,
@@ -255,10 +257,10 @@ fn detect_rsdp(start_address: PhysAddr, end_address: PhysAddr) -> Result<&'stati
 		// Have we crossed a page boundary in the last iteration?
 		if current_address / BasePageSize::SIZE as usize > current_page {
 			// Identity-map this possible page of the RSDP.
-			paging::identity_map(
-				PhysAddr::from(current_address),
-				PhysAddr::from(current_address),
-			);
+			let frame = PhysFrame::<BasePageSize>::containing_address(x86_64::PhysAddr::new(
+				current_address as u64,
+			));
+			paging::identity_map(frame);
 			current_page = current_address / BasePageSize::SIZE as usize;
 		}
 
@@ -304,7 +306,9 @@ fn detect_rsdp(start_address: PhysAddr, end_address: PhysAddr) -> Result<&'stati
 /// Returns a reference to the ACPI RSDP within the Ok() if successful or an empty Err() on failure.
 fn detect_acpi() -> Result<&'static AcpiRsdp, ()> {
 	// Get the address of the EBDA.
-	paging::identity_map(EBDA_PTR_LOCATION, EBDA_PTR_LOCATION);
+	let frame =
+		PhysFrame::<BasePageSize>::containing_address(x86_64::PhysAddr::new(EBDA_PTR_LOCATION.0));
+	paging::identity_map(frame);
 	let ebda_ptr_location: &u16 =
 		unsafe { &*(VirtAddr::from(EBDA_PTR_LOCATION.as_u64()).as_ptr()) };
 	let ebda_address = PhysAddr((*ebda_ptr_location as u64) << 4);

src/arch/x86_64/mm/paging.rs

@@ -239,28 +239,27 @@ pub fn unmap<S: PageSize>(virtual_address: VirtAddr, count: usize) {
 }
 
 #[cfg(feature = "acpi")]
-pub fn identity_map(start_address: PhysAddr, end_address: PhysAddr) {
-	let first_page =
-		Page::<BasePageSize>::containing_address(x86_64::VirtAddr::new(start_address.as_u64()));
-	let last_page =
-		Page::<BasePageSize>::containing_address(x86_64::VirtAddr::new(end_address.as_u64()));
+pub fn identity_map<S>(frame: PhysFrame<S>)
+where
+	S: PageSize + core::fmt::Debug,
+	RecursivePageTable<'static>: Mapper<S>,
+{
 	assert!(
-		last_page.start_address().as_u64() < mm::kernel_start_address().0,
+		frame.start_address().as_u64() < mm::kernel_start_address().0,
 		"Address {:#X} to be identity-mapped is not below Kernel start address",
-		last_page.start_address()
+		frame.start_address()
 	);
 
-	let mut flags = PageTableEntryFlags::empty();
-	flags.normal().read_only().execute_disable();
-	let count = (last_page.start_address().as_u64() - first_page.start_address().as_u64())
-		/ BasePageSize::SIZE
-		+ 1;
-	map::<BasePageSize>(
-		VirtAddr(first_page.start_address().as_u64()),
-		PhysAddr(first_page.start_address().as_u64()),
-		count as usize,
-		flags,
-	);
+	unsafe {
+		recursive_page_table()
+			.identity_map(
+				frame,
+				PageTableEntryFlags::PRESENT | PageTableEntryFlags::NO_EXECUTE,
+				&mut physicalmem::FrameAlloc,
+			)
+			.unwrap()
+			.flush();
+	}
 }
 
 #[inline]