nvic: Make ICSR.RETTOBASE handle banked exceptions

Update the code in nvic_rettobase() so that it checks the
sec_vectors[] array as well as the vectors[] array if needed.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 1505240046-11454-7-git-send-email-peter.maydell@linaro.org

hw/intc/armv7m_nvic.c

@@ -84,9 +84,12 @@ static int nvic_pending_prio(NVICState *s)
 static bool nvic_rettobase(NVICState *s)
 {
     int irq, nhand = 0;
+    bool check_sec = arm_feature(&s->cpu->env, ARM_FEATURE_M_SECURITY);
 
     for (irq = ARMV7M_EXCP_RESET; irq < s->num_irq; irq++) {
-        if (s->vectors[irq].active) {
+        if (s->vectors[irq].active ||
+            (check_sec && irq < NVIC_INTERNAL_VECTORS &&
+             s->sec_vectors[irq].active)) {
             nhand++;
             if (nhand == 2) {
                 return 0;