* Set the new canary */
 	arc4random_buf(&td2->td_md.md_canary, sizeof(td2->td_md.md_canary));
@@ -192,6 +194,8 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
 	td->td_md.md_spinlock_count = 1;
 	td->td_md.md_saved_daif = PSR_DAIF_DEFAULT;
 
+	td->td_md.md_sctlr = td0->td_md.md_sctlr;
+
 #if defined(PERTHREAD_SSP)
 	/* Set the new canary */
 	arc4random_buf(&td->td_md.md_canary, sizeof(td->td_md.md_canary));
diff --git a/sys/arm64/include/armreg.h b/sys/arm64/include/armreg.h
index 6447f0064d33..4233a01d143c 100644
--- a/sys/arm64/include/armreg.h
+++ b/sys/arm64/include/armreg.h
@@ -2803,6 +2803,7 @@
      SCTLR_SA |				\
      SCTLR_C |				\
      SCTLR_M)
+#define	SCTLR_USER_MASK	(SCTLR_ATA0 | SCTLR_TCF0_MASK)
 
 /* SCTLR_EL12 */
 #define	SCTLR_EL12_REG			MRS_REG_ALT_NAME(SCTLR_EL12)
diff --git a/sys/arm64/include/proc.h b/sys/arm64/include/proc.h
index b40990e89385..d5879a794269 100644
--- a/sys/arm64/include/proc.h
+++ b/sys/arm64/include/proc.h
@@ -70,7 +70,8 @@ struct mdthread {
 	int md_efirt_dis_pf;
 
 	int md_reserved0;
-	uint64_t md_reserved[2];
+	uint64_t md_sctlr;
+	uint64_t md_reserved1;
 };
 
 struct mdproc {