Support more operations on PageFlags

src/page/flags.rs

@@ -1,4 +1,7 @@
-use core::marker::PhantomData;
+use core::{
+    fmt,
+    marker::PhantomData
+};
 
 use crate::Arch;
 
@@ -21,6 +24,18 @@ impl<A: Arch> PageFlags<A> {
         }
     }
 
+    #[inline(always)]
+    pub fn new_table() -> Self {
+        unsafe {
+            Self::from_data(
+                // Flags set to present, kernel space, read-only, no-execute by default
+                A::ENTRY_FLAG_DEFAULT_TABLE |
+                A::ENTRY_FLAG_READONLY |
+                A::ENTRY_FLAG_NO_EXEC
+            )
+        }
+    }
+
     #[inline(always)]
     pub unsafe fn from_data(data: usize) -> Self {
         Self { data, phantom: PhantomData }
@@ -31,6 +46,7 @@ impl<A: Arch> PageFlags<A> {
         self.data
     }
 
+    #[must_use]
     #[inline(always)]
     pub fn custom_flag(mut self, flag: usize, value: bool) -> Self {
         if value {
@@ -41,11 +57,28 @@ impl<A: Arch> PageFlags<A> {
         self
     }
 
+    #[inline(always)]
+    pub fn has_flag(&self, flag: usize) -> bool {
+        self.data & flag == flag
+    }
+
+    #[inline(always)]
+    pub fn has_present(&self) -> bool {
+        self.has_flag(A::ENTRY_FLAG_PRESENT)
+    }
+
+    #[must_use]
     #[inline(always)]
     pub fn user(self, value: bool) -> Self {
         self.custom_flag(A::ENTRY_FLAG_USER, value)
     }
 
+    #[inline(always)]
+    pub fn has_user(&self) -> bool {
+        self.has_flag(A::ENTRY_FLAG_USER)
+    }
+
+    #[must_use]
     #[inline(always)]
     pub fn write(self, value: bool) -> Self {
         // Architecture may use readonly or readwrite, support either
@@ -53,6 +86,13 @@ impl<A: Arch> PageFlags<A> {
             .custom_flag(A::ENTRY_FLAG_READWRITE, value)
     }
 
+    #[inline(always)]
+    pub fn has_write(&self) -> bool {
+        // Architecture may use readonly or readwrite, support either
+        self.data & (A::ENTRY_FLAG_READONLY | A::ENTRY_FLAG_READWRITE) == A::ENTRY_FLAG_READWRITE
+    }
+
+    #[must_use]
     #[inline(always)]
     pub fn execute(self, value: bool) -> Self {
         //TODO: write xor execute?
@@ -60,4 +100,18 @@ impl<A: Arch> PageFlags<A> {
         self.custom_flag(A::ENTRY_FLAG_NO_EXEC, !value)
             .custom_flag(A::ENTRY_FLAG_EXEC, value)
     }
+
+    #[inline(always)]
+    pub fn has_execute(&self) -> bool {
+        // Architecture may use no exec or exec, support either
+        self.data & (A::ENTRY_FLAG_NO_EXEC | A::ENTRY_FLAG_EXEC) == A::ENTRY_FLAG_EXEC
+    }
 }
+
+impl<A: Arch> fmt::Debug for PageFlags<A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("PageFlags")
+            .field("data", &self.data)
+            .finish()
+    }
+}