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arm64: mm: Permit transitioning from Global to Non-Global without BBM

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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: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Will Deacon 2018-01-29 11:59:54 +00:00 committed by Greg Kroah-Hartman
parent 6928820180
commit ee28fed5cc
1 changed files with 4 additions and 0 deletions
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4
arch/arm64/mm/mmu.c
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@ -117,6 +117,10 @@ 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;
}