Commit 6477c388 authored by Anshuman Khandual's avatar Anshuman Khandual Committed by Will Deacon
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arm64/mm: Set only the PTE_DIRTY bit while preserving the HW dirty state 



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: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20230713071518.628440-1-anshuman.khandual@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent d0ba9612

arch/arm64/include/asm/pgtable.h

+3 −2
Original line number Diff line number Diff line
@@ -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;

}