[Xen-devel] [PATCH MM-PART2 RESEND v2 18/19] xen/arm: mm: Check start is always before end in {destroy, modify}_xen_mappings

[Julien Grall <julien.grall@xxxxxxx>]

The two helpers {destroy, modify}_xen_mappings don't check that the
start is always before the end. This should never happen but if it
happens, it will result to unexpected behavior.

Catch such issues earlier on by adding an ASSERT in destroy_xen_mappings
and modify_xen_mappings.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Reviewed-by: Andrii Anisov <andrii_anisov@xxxxxxxx>

---
    Changes in v2:
        - Add Andrii's reviewed-by
---
 xen/arch/arm/mm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index eacc1647e0..b408de7c75 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1077,11 +1077,13 @@ int populate_pt_range(unsigned long virt, unsigned long 
nr_mfns)
 
 int destroy_xen_mappings(unsigned long v, unsigned long e)
 {
+    ASSERT(v <= e);
     return create_xen_entries(REMOVE, v, INVALID_MFN, (e - v) >> PAGE_SHIFT, 
0);
 }
 
 int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int flags)
 {
+    ASSERT(s <= e);
     return create_xen_entries(MODIFY, s, INVALID_MFN, (e - s) >> PAGE_SHIFT,
                               flags);
 }
-- 
2.11.0


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