Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.15 043/202] [Variant 3/Meltdown] arm64: mm: Permit transitioning from Global to Non-Global without BBM | Date | Thu, 15 Feb 2018 16:15:43 +0100 |
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4.15-stable review patch. If anyone has any objections, please let me know.
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From: Will Deacon <will.deacon@arm.com>
Commit 4e6020565596 upstream.
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/arm64/mm/mmu.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -117,6 +117,10 @@ static bool pgattr_change_is_safe(u64 ol 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; }
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