1 files changed, 18 insertions, 15 deletions

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 149d05fb9421..3ff03a755c32 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -149,12 +149,20 @@ static inline pte_t pte_mkwrite(pte_t pte)
 
 static inline pte_t pte_mkclean(pte_t pte)
 {
-        return clear_pte_bit(pte, __pgprot(PTE_DIRTY));
+        pte = clear_pte_bit(pte, __pgprot(PTE_DIRTY));
+        pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
+
+        return pte;
 }
 
 static inline pte_t pte_mkdirty(pte_t pte)
 {
-        return set_pte_bit(pte, __pgprot(PTE_DIRTY));
+        pte = set_pte_bit(pte, __pgprot(PTE_DIRTY));
+
+        if (pte_write(pte))
+                pte = clear_pte_bit(pte, __pgprot(PTE_RDONLY));
+
+        return pte;
 }
 
 static inline pte_t pte_mkold(pte_t pte)
@@ -641,28 +649,23 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 /*
- * ptep_set_wrprotect - mark read-only while preserving the hardware update of
- * the Access Flag.
+ * ptep_set_wrprotect - mark read-only while trasferring potential hardware
+ * dirty status (PTE_DBM && !PTE_RDONLY) to the software PTE_DIRTY bit.
  */
 #define __HAVE_ARCH_PTEP_SET_WRPROTECT
 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
 {
         pte_t old_pte, pte;
 
-        /*
-         * ptep_set_wrprotect() is only called on CoW mappings which are
-         * private (!VM_SHARED) with the pte either read-only (!PTE_WRITE &&
-         * PTE_RDONLY) or writable and software-dirty (PTE_WRITE &&
-         * !PTE_RDONLY && PTE_DIRTY); see is_cow_mapping() and
-         * protection_map[]. There is no race with the hardware update of the
-         * dirty state: clearing of PTE_RDONLY when PTE_WRITE (a.k.a. PTE_DBM)
-         * is set.
-         */
-        VM_WARN_ONCE(pte_write(*ptep) && !pte_dirty(*ptep),
-                     "%s: potential race with hardware DBM", __func__);
         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));