[PATCH v3 06/13] arm64: mm: Permit contiguous descriptors to be rewritten

[Ard Biesheuvel]

From: Ard Biesheuvel <ardb@xxxxxxxxxx>

Currently, pgattr_change_is_safe() is overly pedantic when it comes to
descriptors with the contiguous hint attribute set, as it rejects
assignments even if the old and the new value are the same.

So relax the check to allow that.

Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
 arch/arm64/mm/mmu.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 744cf76f25aa..6780236b6cf8 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -140,10 +140,6 @@ bool pgattr_change_is_safe(pteval_t old, pteval_t new)
 	if (pte_pfn(__pte(old)) != pte_pfn(__pte(new)))
 		return false;
 
-	/* live contiguous mappings may not be manipulated at all */
-	if ((old | new) & PTE_CONT)
-		return false;
-
 	/* Transitioning from Non-Global to Global is unsafe */
 	if (old & ~new & PTE_NG)
 		return false;
-- 
2.53.0.959.g497ff81fa9-goog