From 733e6db9736d1d29cbc4d69a60cfe3bd3be77620 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 20 Nov 2020 13:57:48 +0000 Subject: [PATCH] arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect() commit ff1712f953e27f0b0718762ec17d0adb15c9fd0b upstream. 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: Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits") Reviewed-by: Catalin Marinas Link: https://lore.kernel.org/r/20201120143557.6715-3-will@kernel.org Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- 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 ac6bd56e970d..69dfc340e71b 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -136,13 +136,6 @@ static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot) return pte; } -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)); @@ -168,6 +161,20 @@ 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)); @@ -783,12 +790,6 @@ 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));