From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: david@redhat.com, Anshuman Khandual <anshuman.khandual@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] arm64/mm: Set only the PTE_DIRTY bit while preserving the HW dirty state
Date: Thu, 13 Jul 2023 12:45:18 +0530 [thread overview]
Message-ID: <20230713071518.628440-1-anshuman.khandual@arm.com> (raw)
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>
---
This applies on v6.5-rc1
arch/arm64/include/asm/pgtable.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 0bd18de9fd97..171d6d7f8087 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -212,7 +212,7 @@ 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));
@@ -823,7 +823,8 @@ 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;
}
--
2.30.2
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next reply other threads:[~2023-07-13 7:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-13 7:15 Anshuman Khandual [this message]
2023-07-13 12:17 ` [PATCH] arm64/mm: Set only the PTE_DIRTY bit while preserving the HW dirty state David Hildenbrand
2023-07-21 18:23 ` Catalin Marinas
2023-07-27 12:22 ` Will Deacon
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