[PATCH v4 07/15] arm64: mm: Permit contiguous descriptors to be rewritten

[Ard Biesheuvel]

From: Ard Biesheuvel <ardb at kernel.org>

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 at kernel.org>
---
 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 9610dd2d7bd9..bfb2f1cae724 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -134,10 +134,6 @@ 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;
-- 
2.54.0.rc2.544.gc7ae2d5bb8-goog