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Date: Fri, 20 Nov 2020 14:35:53 +0000 From: Will Deacon <will@...nel.org> To: linux-kernel@...r.kernel.org Cc: kernel-team@...roid.com, Will Deacon <will@...nel.org>, Catalin Marinas <catalin.marinas@....com>, Yu Zhao <yuzhao@...gle.com>, Minchan Kim <minchan@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org, stable@...r.kernel.org Subject: [PATCH 2/6] arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect() 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@...r.kernel.org> Signed-off-by: Will Deacon <will@...nel.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
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