From: Minchan Kim <minchan@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
Catalin Marinas <catalin.marinas@arm.com>,
Yu Zhao <yuzhao@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
stable@vger.kernel.org
Subject: Re: [PATCH 2/6] arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect()
Date: Fri, 20 Nov 2020 09:09:03 -0800 [thread overview]
Message-ID: <20201120170903.GC3377168@google.com> (raw)
In-Reply-To: <20201120143557.6715-3-will@kernel.org>
On Fri, Nov 20, 2020 at 02:35:53PM +0000, Will Deacon wrote:
> With hardware dirty bit management, calling pte_wrprotect() on a writable,
> dirty PTE will lose the dirty state and return a read-only, clean entry.
>
> Move the logic from ptep_set_wrprotect() into pte_wrprotect() to ensure that
> the dirty bit is preserved for writable entries, as this is required for
> soft-dirty bit management if we enable it in the future.
>
> Cc: <stable@vger.kernel.org>
It this stable material if it would be a problem once ARM64 supports
softdirty in future?
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
> arch/arm64/include/asm/pgtable.h | 27 ++++++++++++++-------------
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 1bdf51f01e73..a155551863c9 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -162,13 +162,6 @@ static inline pmd_t set_pmd_bit(pmd_t pmd, pgprot_t prot)
> return pmd;
> }
>
> -static inline pte_t pte_wrprotect(pte_t pte)
> -{
> - pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
> - pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
> - return pte;
> -}
> -
> static inline pte_t pte_mkwrite(pte_t pte)
> {
> pte = set_pte_bit(pte, __pgprot(PTE_WRITE));
> @@ -194,6 +187,20 @@ static inline pte_t pte_mkdirty(pte_t pte)
> return pte;
> }
>
> +static inline pte_t pte_wrprotect(pte_t pte)
> +{
> + /*
> + * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
> + * clear), set the PTE_DIRTY bit.
> + */
> + if (pte_hw_dirty(pte))
> + pte = pte_mkdirty(pte);
> +
> + pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
> + pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
> + return pte;
> +}
> +
> static inline pte_t pte_mkold(pte_t pte)
> {
> return clear_pte_bit(pte, __pgprot(PTE_AF));
> @@ -843,12 +850,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
> pte = READ_ONCE(*ptep);
> do {
> old_pte = pte;
> - /*
> - * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
> - * clear), set the PTE_DIRTY bit.
> - */
> - if (pte_hw_dirty(pte))
> - pte = pte_mkdirty(pte);
> pte = pte_wrprotect(pte);
> pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
> pte_val(old_pte), pte_val(pte));
> --
> 2.29.2.454.gaff20da3a2-goog
>
next prev parent reply other threads:[~2020-11-20 17:09 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 14:35 [PATCH 0/6] tlb: Fix access and (soft-)dirty bit management Will Deacon
2020-11-20 14:35 ` [PATCH 1/6] arm64: pgtable: Fix pte_accessible() Will Deacon
2020-11-20 16:03 ` Minchan Kim
2020-11-20 19:53 ` Yu Zhao
2020-11-23 13:27 ` Catalin Marinas
2020-11-24 10:02 ` Anshuman Khandual
2020-11-20 14:35 ` [PATCH 2/6] arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect() Will Deacon
2020-11-20 17:09 ` Minchan Kim [this message]
2020-11-23 14:31 ` Catalin Marinas
2020-11-23 14:22 ` Catalin Marinas
2020-11-20 14:35 ` [PATCH 3/6] tlb: mmu_gather: Remove unused start/end arguments from tlb_finish_mmu() Will Deacon
2020-11-20 17:20 ` Linus Torvalds
2020-11-23 16:48 ` Will Deacon
2020-11-20 14:35 ` [PATCH 4/6] mm: proc: Invalidate TLB after clearing soft-dirty page state Will Deacon
2020-11-20 15:00 ` Peter Zijlstra
2020-11-20 15:09 ` Peter Zijlstra
2020-11-20 15:15 ` Will Deacon
2020-11-20 15:27 ` Peter Zijlstra
2020-11-23 18:23 ` Will Deacon
2020-11-20 15:55 ` Minchan Kim
2020-11-23 18:41 ` Will Deacon
2020-11-25 22:51 ` Minchan Kim
2020-11-20 20:22 ` Yu Zhao
2020-11-21 2:49 ` Yu Zhao
2020-11-23 19:21 ` Yu Zhao
2020-11-23 22:04 ` Will Deacon
2020-11-20 14:35 ` [PATCH 5/6] tlb: mmu_gather: Introduce tlb_gather_mmu_fullmm() Will Deacon
2020-11-20 17:22 ` Linus Torvalds
2020-11-20 17:31 ` Linus Torvalds
2020-11-23 16:48 ` Will Deacon
2020-11-22 15:11 ` [tlb] e242a269fa: WARNING:at_mm/mmu_gather.c:#tlb_gather_mmu kernel test robot
2020-11-23 17:51 ` Will Deacon
2020-11-20 14:35 ` [PATCH 6/6] mm: proc: Avoid fullmm flush for young/dirty bit toggling Will Deacon
2020-11-20 17:41 ` Linus Torvalds
2020-11-20 17:45 ` Linus Torvalds
2020-11-20 20:40 ` Yu Zhao
2020-11-23 18:35 ` Will Deacon
2020-11-23 20:04 ` Yu Zhao
2020-11-23 21:17 ` Will Deacon
2020-11-24 1:13 ` Yu Zhao
2020-11-24 14:31 ` Will Deacon
2020-11-25 22:01 ` Minchan Kim
2020-11-24 14:46 ` Peter Zijlstra
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