add const visitor for page_table

yodalee · May 20, 2022 · d2855b1 · d2855b1
1 parent 149ba1e
commit d2855b1
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Showing 2 changed files with 50 additions and 5 deletions.
diff --git a/src/kvm.rs b/src/kvm.rs
@@ -2,7 +2,7 @@ use rv64::csr::satp::{Satp, SatpMode};
 use rv64::asm::sfence_vma;
 
 use crate::vm::page_table::{PageTable, PageTableLevel, PageTableEntry};
-use crate::vm::page_table_walker::{PageTableVisitor, PageTableWalkerMut};
+use crate::vm::page_table_walker::{PageTableVisitorMut, PageTableWalkerMut};
 use crate::vm::addr::{VirtAddr, PhysAddr, align_up, align_down};
 use crate::vm::page_flag::PteFlag;
 use crate::riscv::{PAGESIZE, MAXVA};
@@ -86,7 +86,7 @@ struct PageMapper {
     perm: PteFlag
 }
 
-impl PageTableVisitor for PageMapper {
+impl PageTableVisitorMut for PageMapper {
     type Output = Result<(), &'static str>;
     fn is_valid_va(&self, va: VirtAddr) -> bool {
         va < VirtAddr::new(MAXVA)
@@ -118,7 +118,7 @@ struct PageUnmapper {
     do_free: bool
 }
 
-impl PageTableVisitor for PageUnmapper {
+impl PageTableVisitorMut for PageUnmapper {
     type Output = Result<(), &'static str>;
     fn is_valid_va(&self, va: VirtAddr) -> bool {
         va < VirtAddr::new(MAXVA)

diff --git a/src/vm/page_table_walker.rs b/src/vm/page_table_walker.rs
@@ -9,14 +9,14 @@ pub struct PageTableWalkerMut<'a, Extra> {
     pub extra: Extra,
 }
 
-pub trait PageTableVisitor {
+pub trait PageTableVisitorMut {
     type Output : core::ops::Try;
     fn is_valid_va(&self, va: VirtAddr) -> bool;
     fn leaf(&mut self, pte: &mut PageTableEntry) -> Self::Output;
     fn nonleaf(&mut self, pte: &mut PageTableEntry) -> Self::Output;
 }
 
-impl<'a, Extra: PageTableVisitor> PageTableWalkerMut<'a, Extra> {
+impl<'a, Extra: PageTableVisitorMut> PageTableWalkerMut<'a, Extra> {
     pub fn new(page_table: &'a mut PageTable, va: VirtAddr, level: PageTableLevel, extra: Extra) -> Option<Self> {
         extra.is_valid_va(va).then(
             move || Self {
@@ -46,3 +46,48 @@ impl<'a, Extra: PageTableVisitor> PageTableWalkerMut<'a, Extra> {
         }
     }
 }
+
+pub struct PageTableWalker<'a, Extra> {
+    pub page_table: &'a PageTable,
+    pub va: VirtAddr,
+    pub level: PageTableLevel,
+    pub extra: Extra,
+}
+
+pub trait PageTableVisitor {
+    type Output : core::ops::Try;
+    fn is_valid_va(&self, va: VirtAddr) -> bool;
+    fn leaf(&self, pte: &PageTableEntry) -> Self::Output;
+    fn nonleaf(&self, pte: &PageTableEntry) -> Self::Output;
+}
+
+impl<'a, Extra: PageTableVisitor> PageTableWalker<'a, Extra> {
+    pub fn new(page_table: &'a PageTable, va: VirtAddr, level: PageTableLevel, extra: Extra) -> Option<Self> {
+        extra.is_valid_va(va).then(
+            move || Self {
+                page_table,
+                va,
+                level,
+                extra
+            }
+        )
+    }
+    pub fn visit(&mut self) -> Extra::Output {
+        let index = self.va.get_index(self.level);
+        let pte = &self.page_table[index];
+
+        match self.level.next_level() {
+            None => {
+                self.extra.leaf(pte)
+            }
+            Some(next_level) => {
+                let _ = self.extra.nonleaf(pte)?;
+
+                let next_table = unsafe { &*(pte.addr() as *const PageTable) };
+                self.page_table = next_table;
+                self.level = next_level;
+                self.visit()
+            }
+        }
+    }
+}