feat: add guard page

marekvospel · Nov 26, 2023 · 1dc5fb2 · 1dc5fb2
1 parent 4ca6684
commit 1dc5fb2
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Showing 3 changed files with 8 additions and 6 deletions.
diff --git a/src/memory/frames/bump_alloc.rs b/src/memory/frames/bump_alloc.rs
@@ -2,6 +2,8 @@ use core::ops::RangeInclusive;
 
 use multiboot2::{MemoryArea, MemoryAreaType};
 
+use crate::println;
+
 use super::{FrameAlloc, PhysicalFrame, PAGE_SIZE};
 
 pub struct BumpAllocator<'a> {
@@ -70,6 +72,7 @@ impl<'a> FrameAlloc for BumpAllocator<'a> {
     }
 
     fn deallocate_frame(&mut self, _frame: PhysicalFrame) {
-        unimplemented!()
+        println!("[WARN] Trying to deallocate a frame, BumpAllocator doesn't support that");
+        // unimplemented!()
     }
 }
diff --git a/src/memory/mod.rs b/src/memory/mod.rs
@@ -96,9 +96,10 @@ fn remap_kernel<A: FrameAlloc>(
         mapper.identity_map(vga_text, EntryFlags::WRITABLE, allocator);
     });
 
-    active_table.switch(new_table);
+    let old_table = active_table.switch(new_table);
 
-    // TODO: guard page
+    let old_page = Page::containing_address(old_table.p4_frame.start_address());
+    active_table.unmap(old_page, allocator);
 }
 
 fn enable_write_protect_bit() {

diff --git a/src/memory/paging/mapper.rs b/src/memory/paging/mapper.rs
@@ -168,9 +168,7 @@ impl ActivePageTable {
         let old = Cr3::read();
 
         let old_table = InactivePageTable {
-            p4_frame: PhysicalFrame {
-                number: old.0.start_address().as_u64(),
-            },
+            p4_frame: PhysicalFrame::by_addr(old.0.start_address().as_u64()),
         };
         unsafe {
             Cr3::write(