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.
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);-- 2.29.2.454.gaff20da3a2-goog