Fixed page size, fuzzer now does memory.

hbvm/fuzz/fuzz_targets/vm.rs

@@ -10,10 +10,34 @@ use {
 
 fuzz_target!(|data: &[u8]| {
     if let Ok(mut vm) = Vm::<_, 16384>::new_validated(data, TestTrapHandler, Default::default()) {
+        let page = Box::into_raw(Box::<Page>::default());
+
+        unsafe {
+            vm.memory
+                .map(
+                    page.cast(),
+                    0,
+                    hbvm::mem::paging::Permission::Write,
+                    PageSize::Size4K,
+                )
+                .unwrap()
+        };
+
         let _ = vm.run();
+
+        vm.memory.unmap(0).unwrap();
+        let _ = unsafe { Box::from_raw(page) };
     }
 });
 
+#[repr(align(4096))]
+struct Page([u8; 4096]);
+impl Default for Page {
+    fn default() -> Self {
+        unsafe { std::mem::MaybeUninit::zeroed().assume_init() }
+    }
+}
+
 struct TestTrapHandler;
 impl HandlePageFault for TestTrapHandler {
     fn page_fault(

hbvm/src/mem/mod.rs

@@ -365,7 +365,7 @@ impl Iterator for AddrPageLookuper {
                                 perm,
                                 PageSize::from_lvl(lvl)?,
                                 // In-page offset
-                                self.addr as usize & ((1 << (lvl * 9 + 12)) - 1),
+                                addr_extract_index(self.addr, lvl),
                             );
                         }
                     }
@@ -393,7 +393,7 @@ impl Iterator for AddrPageLookuper {
 /// the output of the function is unspecified (yes, it can also panic :)
 pub fn addr_extract_index(addr: u64, lvl: u8) -> usize {
     debug_assert!(lvl <= 4);
-    usize::try_from((addr >> (lvl * 9 + 12)) & ((1 << 9) - 1)).expect("?conradluget a better CPU")
+    usize::try_from((addr >> (lvl * 8 + 12)) & ((1 << 8) - 1)).expect("?conradluget a better CPU")
 }
 
 /// Page size