[RFC PATCH v2 11/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW

@@ -1170,7 +1170,18 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
 static inline void ptep_set_wrprotect(struct mm_struct *mm,
 				      unsigned long addr, pte_t *ptep)
 {
+	pte_t pte;
+
 	clear_bit(_PAGE_BIT_RW, (unsigned long *)&ptep->pte);
+	pte = *ptep;
+
+	/*
+	 * On platforms before CET, other threads could race to
+	 * create a RO and _PAGE_DIRTY_HW PTE again.  However,
+	 * on CET platforms, this is safe without a TLB flush.
+	 */
+	pte = pte_move_flags(pte, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW);
+	set_pte_at(mm, addr, ptep, pte);
 }
 
 #define flush_tlb_fix_spurious_fault(vma, address) do { } while (0)

@@ -1220,7 +1231,18 @@ static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm,
 static inline void pmdp_set_wrprotect(struct mm_struct *mm,
 				      unsigned long addr, pmd_t *pmdp)
 {
+	pmd_t pmd;
+
 	clear_bit(_PAGE_BIT_RW, (unsigned long *)pmdp);
+	pmd = *pmdp;
+
+	/*
+	 * On platforms before CET, other threads could race to
+	 * create a RO and _PAGE_DIRTY_HW PMD again.  However,
+	 * on CET platforms, this is safe without a TLB flush.
+	 */
+	pmd = pmd_move_flags(pmd, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW);
+	set_pmd_at(mm, addr, pmdp, pmd);
 }
 
 #define pud_write pud_write