From: Will Deacon <will.deacon@arm.com>
Date: Mon, 29 Jan 2018 11:59:54 +0000
Subject: arm64: mm: Permit transitioning from Global to Non-Global without BBM
Patch-mainline: v4.16-rc1
Git-commit: 4e602056559633303d7e5bb2ff624778ca248f68
References: bsc#1068032
Break-before-make is not needed when transitioning from Global to
Non-Global mappings, provided that the contiguous hint is not being used.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
arch/arm64/mm/mmu.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index b44992ec9643..fc7902bda02b 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -118,6 +118,10 @@ static bool pgattr_change_is_safe(u64 old, u64 new)
if ((old | new) & PTE_CONT)
return false;
+ /* Transitioning from Global to Non-Global is safe */
+ if (((old ^ new) == PTE_NG) && (new & PTE_NG))
+ return true;
+
return ((old ^ new) & ~mask) == 0;
}