[PATCH v2 1/2] rust: mm: add VmaRef range query helpers

From: liujinlong <[email protected]>

Add helpers on VmaRef to query the virtual address span and test
address membership:

  range()               - returns core::ops::Range<usize> covering
                          [vm_start, vm_end), giving callers access
                          to all standard Range methods (len(),
                          contains(), iteration, etc.)
  contains_range()      - sub-range membership, returns false
                          on overflow
  is_page_aligned()     - PAGE_SIZE alignment for one address
  is_page_aligned_range() - PAGE_SIZE alignment for addr and size

is_page_aligned() and is_page_aligned_range() are associated
functions rather than methods, since they do not reference any VMA
state.  They live here instead of a separate utility module to
keep the page-alignment helpers close to the range-checking code
that often uses them.

Signed-off-by: liujinlong <[email protected]>
---
 rust/kernel/mm/virt.rs | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs
index 63eb730b0b05..c11fb4c089bd 100644
--- a/rust/kernel/mm/virt.rs
+++ b/rust/kernel/mm/virt.rs
@@ -18,7 +18,7 @@
     bindings,
     error::{code::EINVAL, to_result, Result},
     mm::MmWithUser,
-    page::Page,
+    page::{Page, PAGE_SIZE},
     types::Opaque,
 };
 
@@ -92,6 +92,36 @@ pub fn end(&self) -> usize {
         unsafe { (*self.as_ptr()).__bindgen_anon_1.__bindgen_anon_1.vm_end }
     }
 
+    /// Return the virtual address range `[vm_start, vm_end)` of this
+    /// VMA as a [`Range<usize>`], giving callers access to all the
+    /// standard range methods (`len()`, `contains()`, iteration, etc.).
+    #[inline]
+    pub fn range(&self) -> core::ops::Range<usize> {
+        self.start()..self.end()
+    }
+
+    /// True if `[addr, addr + size)` lies in `[vm_start, vm_end)`;
+    /// returns false on overflow.
+    #[inline]
+    pub fn contains_range(&self, addr: usize, size: usize) -> bool {
+        let Some(end) = addr.checked_add(size) else {
+            return false;
+        };
+        self.start() <= addr && end <= self.end()
+    }
+
+    /// True if `addr` is `PAGE_SIZE`-aligned.
+    #[inline]
+    pub fn is_page_aligned(addr: usize) -> bool {
+        addr % PAGE_SIZE == 0
+    }
+
+    /// True if `addr` and `size` are both page-aligned.
+    #[inline]
+    pub fn is_page_aligned_range(addr: usize, size: usize) -> bool {
+        Self::is_page_aligned(addr) && Self::is_page_aligned(size)
+    }
+
     /// Zap pages in the given page range.
     ///
     /// This clears page table mappings for the range at the leaf level, leaving all other page
-- 
2.25.1