1 files changed, 21 insertions, 6 deletions

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 0b10204e72fc..c0ba8cdfa10a 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -314,9 +314,25 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 	if (pte_present(pte) && pte_user_exec(pte) && !pte_special(pte))
 		__sync_icache_dcache(pte);
 
-	if (system_supports_mte() &&
-	    pte_present(pte) && pte_tagged(pte) && !pte_special(pte))
-		mte_sync_tags(ptep, pte);
+	/*
+	 * If the PTE would provide user space access to the tags associated
+	 * with it then ensure that the MTE tags are synchronised.  Although
+	 * pte_access_permitted() returns false for exec only mappings, they
+	 * don't expose tags (instruction fetches don't check tags).
+	 */
+	if (system_supports_mte() && pte_access_permitted(pte, false) &&
+	    !pte_special(pte)) {
+		pte_t old_pte = READ_ONCE(*ptep);
+		/*
+		 * We only need to synchronise if the new PTE has tags enabled
+		 * or if swapping in (in which case another mapping may have
+		 * set tags in the past even if this PTE isn't tagged).
+		 * (!pte_none() && !pte_present()) is an open coded version of
+		 * is_swap_pte()
+		 */
+		if (pte_tagged(pte) || (!pte_none(old_pte) && !pte_present(old_pte)))
+			mte_sync_tags(old_pte, pte);
+	}
 
 	__check_racy_pte_update(mm, ptep, pte);
 
@@ -511,13 +527,12 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 
 #define pmd_none(pmd)		(!pmd_val(pmd))
 
-#define pmd_bad(pmd)		(!(pmd_val(pmd) & PMD_TABLE_BIT))
-
 #define pmd_table(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
 				 PMD_TYPE_TABLE)
 #define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
 				 PMD_TYPE_SECT)
 #define pmd_leaf(pmd)		pmd_sect(pmd)
+#define pmd_bad(pmd)		(!pmd_table(pmd))
 
 #define pmd_leaf_size(pmd)	(pmd_cont(pmd) ? CONT_PMD_SIZE : PMD_SIZE)
 #define pte_leaf_size(pte)	(pte_cont(pte) ? CONT_PTE_SIZE : PAGE_SIZE)
@@ -604,7 +619,7 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
 	pr_err("%s:%d: bad pmd %016llx.\n", __FILE__, __LINE__, pmd_val(e))
 
 #define pud_none(pud)		(!pud_val(pud))
-#define pud_bad(pud)		(!(pud_val(pud) & PUD_TABLE_BIT))
+#define pud_bad(pud)		(!pud_table(pud))
 #define pud_present(pud)	pte_present(pud_pte(pud))
 #define pud_leaf(pud)		pud_sect(pud)
 #define pud_valid(pud)		pte_valid(pud_pte(pud))