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arm64/mm: Set only the PTE_DIRTY bit while preserving the HW dirty state

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pte_mkdirty() creates dirty states both in SW and HW bits, which is really
not required, either in pte_wrprotect() or pte_modify() for preserving the
HW dirty state. Because pte_mkdirty() sets PTE_DIRTY and clears PTE_RDONLY
as pte_write() always evaluates to be true - otherwise pte_hw_dirty() will
not test out in the first place. Clearing PTE_RDONLY again is not required
here because the pte is already in pte_hw_dirty() but might soon loose its
dirty state thus requiring preservation in SW dirty bit i.e PTE_DIRTY.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20230713071518.628440-1-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Anshuman Khandual 2023-07-13 12:45:18 +05:30 committed by Will Deacon
parent d0ba961217
commit 6477c3886a
1 changed files with 3 additions and 2 deletions
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5
arch/arm64/include/asm/pgtable.h
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@ -213,7 +213,7 @@ static inline pte_t pte_wrprotect(pte_t pte)
* clear), set the PTE_DIRTY bit.
*/
if (pte_hw_dirty(pte))
pte = pte_mkdirty(pte);
pte = set_pte_bit(pte, __pgprot(PTE_DIRTY));
pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
@ -824,7 +824,8 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
PTE_ATTRINDX_MASK;
/* preserve the hardware dirty information */
if (pte_hw_dirty(pte))
pte = pte_mkdirty(pte);
pte = set_pte_bit(pte, __pgprot(PTE_DIRTY));
pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
return pte;
}