Make update_flags unsafe too

rust-osdev · Apr 11, 2020 · 604a79b · 604a79b
1 parent 5f578f7
commit 604a79b
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Showing 4 changed files with 24 additions and 10 deletions.
diff --git a/src/structures/paging/mapper/mapped_page_table.rs b/src/structures/paging/mapper/mapped_page_table.rs
@@ -161,7 +161,7 @@ impl<'a, P: PhysToVirt> Mapper<Size1GiB> for MappedPageTable<'a, P> {
         Ok((frame, MapperFlush::new(page)))
     }
 
-    fn update_flags(
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size1GiB>,
         flags: PageTableFlags,
@@ -237,7 +237,7 @@ impl<'a, P: PhysToVirt> Mapper<Size2MiB> for MappedPageTable<'a, P> {
         Ok((frame, MapperFlush::new(page)))
     }
 
-    fn update_flags(
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size2MiB>,
         flags: PageTableFlags,
@@ -315,7 +315,7 @@ impl<'a, P: PhysToVirt> Mapper<Size4KiB> for MappedPageTable<'a, P> {
         Ok((frame, MapperFlush::new(page)))
     }
 
-    fn update_flags(
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size4KiB>,
         flags: PageTableFlags,

diff --git a/src/structures/paging/mapper/mod.rs b/src/structures/paging/mapper/mod.rs
@@ -128,7 +128,15 @@ pub trait Mapper<S: PageSize> {
     fn unmap(&mut self, page: Page<S>) -> Result<(PhysFrame<S>, MapperFlush<S>), UnmapError>;
 
     /// Updates the flags of an existing mapping.
-    fn update_flags(
+    ///
+    /// ## Safety
+    ///
+    /// This method is unsafe because changing the flags of a mapping
+    /// might result in undefined behavior. For example, setting the
+    /// `GLOBAL` and `MUTABLE` flags for a page might result in the corruption
+    /// of values stored in that page from processes running in other address
+    /// spaces.
+    unsafe fn update_flags(
         &mut self,
         page: Page<S>,
         flags: PageTableFlags,

diff --git a/src/structures/paging/mapper/offset_page_table.rs b/src/structures/paging/mapper/offset_page_table.rs
@@ -75,7 +75,7 @@ impl<'a> Mapper<Size1GiB> for OffsetPageTable<'a> {
     }
 
     #[inline]
-    fn update_flags(
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size1GiB>,
         flags: PageTableFlags,
@@ -113,7 +113,7 @@ impl<'a> Mapper<Size2MiB> for OffsetPageTable<'a> {
     }
 
     #[inline]
-    fn update_flags(
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size2MiB>,
         flags: PageTableFlags,
@@ -151,7 +151,7 @@ impl<'a> Mapper<Size4KiB> for OffsetPageTable<'a> {
     }
 
     #[inline]
-    fn update_flags(
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size4KiB>,
         flags: PageTableFlags,

diff --git a/src/structures/paging/mapper/recursive_page_table.rs b/src/structures/paging/mapper/recursive_page_table.rs
@@ -267,7 +267,9 @@ impl<'a> Mapper<Size1GiB> for RecursivePageTable<'a> {
         Ok((frame, MapperFlush::new(page)))
     }
 
-    fn update_flags(
+    // allow unused_unsafe until https://github.com/rust-lang/rust/pull/69245 lands
+    #[allow(unused_unsafe)]
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size1GiB>,
         flags: PageTableFlags,
@@ -359,7 +361,9 @@ impl<'a> Mapper<Size2MiB> for RecursivePageTable<'a> {
         Ok((frame, MapperFlush::new(page)))
     }
 
-    fn update_flags(
+    // allow unused_unsafe until https://github.com/rust-lang/rust/pull/69245 lands
+    #[allow(unused_unsafe)]
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size2MiB>,
         flags: PageTableFlags,
@@ -465,7 +469,9 @@ impl<'a> Mapper<Size4KiB> for RecursivePageTable<'a> {
         Ok((frame, MapperFlush::new(page)))
     }
 
-    fn update_flags(
+    // allow unused_unsafe until https://github.com/rust-lang/rust/pull/69245 lands
+    #[allow(unused_unsafe)]
+    unsafe fn update_flags(
         &mut self,
         page: Page<Size4KiB>,
         flags: PageTableFlags,