1 files changed, 12 insertions, 0 deletions
diff --git a/el3/el3.c b/el3/el3.c
index 78e69d1..f8c9107 100644
--- a/el3/el3.c
+++ b/el3/el3.c
@@ -328,6 +328,18 @@ void el3_start(uintptr_t base, uintptr_t size)
 
     el3_monitor_init();
 
+    /* Initialize SCR. In particular, we must ensure that SCR_EL3.RW is 1
+     * so that we define EL1 as AArch64; otherwise the exception return
+     * will fail; we also want SCR_EL3.NS to be 0.
+     * Setting SCR_ST and SCR_HCE isn't necessary but this configuration
+     * is essentially "turn off all the trap-to-EL3 possibilities".
+     */
+#ifdef AARCH64
+    WRITE_SCR(SCR_ST | SCR_RW | SCR_HCE);
+#else
+    WRITE_SCR(SCR_HCE);
+#endif
+
     /* Set-up our state to return to secure EL1 to start its init on exception
      * return.
      */