fix(vm): fix unmap silently not fully unmapping

Bug description:
offset.unmap_range() bailed out if unmap() internally returned an error.
The original intention was that the caller may choose to ignore the page
not mapped errors as of demand paging. This obviously due to bad API
design decision bailed out early instead of unmapping the rest of the
address range aswell. Causing all sorts of bugs. Now its fixed, yay!
(xfe also works now)

Signed-off-by: Anhad Singh <[email protected]>

src/aero_kernel/src/mem/paging/mapper.rs

@@ -1128,15 +1128,6 @@ impl<'a> Translate for OffsetPageTable<'a> {
 }
 
 impl<'a> OffsetPageTable<'a> {
-    pub fn unmap_range(&mut self, range: Range<VirtAddr>, step: u64) -> Result<(), UnmapError> {
-        for addr in range.step_by(step as usize) {
-            let page: Page = Page::containing_address(addr);
-            self.inner.unmap(page)?.1.flush();
-        }
-
-        Ok(())
-    }
-
     pub fn copy_page_range(&mut self, src: &mut OffsetPageTable, range: RangeInclusive<VirtAddr>) {
         let mut map_to = |src: &mut OffsetPageTable, addr, frame, flags| match frame {
             MappedFrame::Size4KiB(frame) => {

src/aero_kernel/src/userland/vm.rs

@@ -16,6 +16,7 @@
 // along with Aero. If not, see <https://www.gnu.org/licenses/>.
 
 use core::fmt::Write;
+use core::ops::Range;
 
 use aero_syscall::{MMapFlags, MMapProt};
 
@@ -733,16 +734,17 @@ impl Mapping {
         start: VirtAddr,
         end: VirtAddr,
     ) -> Result<UnmapResult, UnmapError> {
-        let mut unmap_range_inner = |range| -> Result<(), UnmapError> {
-            match offset_table.unmap_range(range, Size4KiB::SIZE) {
-                Ok(_) => Ok(()),
-
-                // its fine since technically we are not actually allocating the range
-                // and they are just allocated on faults. So there might be a chance where we
-                // try to unmap a region that is mapped but not actually allocated.
-                Err(UnmapError::PageNotMapped) => Ok(()),
-                Err(err) => Err(err),
+        let mut unmap_range_inner = |range: Range<VirtAddr>| -> Result<(), UnmapError> {
+            for addr in range.step_by(Size4KiB::SIZE as usize) {
+                let page: Page = Page::containing_address(addr);
+                match offset_table.unmap(page) {
+                    Ok((_, flusher)) => flusher.flush(),
+                    Err(UnmapError::PageNotMapped) => {}
+                    Err(e) => return Err(e),
+                }
             }
+
+            Ok(())
         };
 
         if end <= self.start_addr || start >= self.end_addr {