armv8-m: make the securefault handled by non-securefult

arch/arm/src/armv8-m/arm_securefault.c

@@ -41,6 +41,38 @@
 
 #ifdef CONFIG_DEBUG_SECUREFAULT
 #  define sfalert(format, ...)  _alert(format, ##__VA_ARGS__)
+
+#  define OFFSET_R0              (0 * 4) /* R0 */
+#  define OFFSET_R1              (1 * 4) /* R1 */
+#  define OFFSET_R2              (2 * 4) /* R2 */
+#  define OFFSET_R3              (3 * 4) /* R3 */
+#  define OFFSET_R12             (4 * 4) /* R12 */
+#  define OFFSET_R14             (5 * 4) /* R14 = LR */
+#  define OFFSET_R15             (6 * 4) /* R15 = PC */
+#  define OFFSET_XPSR            (7 * 4) /* xPSR */
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static void generate_nonsecure_busfault(void)
+{
+  uint32_t nsp;
+
+  /* Get non-secure SP */
+
+  __asm__ __volatile__ ("mrs %0, msp_ns" : "=r" (nsp));
+
+  sfalert("Non-sec sp %08" PRIx32 "\n", nsp);
+  syslog_flush();
+
+  /* Force set return ReturnAddress to 0, then non-secure cpu will crash.
+   * Also, the ReturnAddress is very important, so move it to R12.
+   */
+
+  putreg32(getreg32(nsp + OFFSET_R15), nsp + OFFSET_R12);
+  putreg32(0, nsp + OFFSET_R15);
+}
 #else
 #  define sfalert(...)
 #endif
@@ -49,6 +81,19 @@
  * Public Functions
  ****************************************************************************/
 
+/****************************************************************************
+ * Name: arm_securefault_should_generate
+ *
+ * Description:
+ *   Check whether should generate non-secure IRQ from securefault
+ *
+ ****************************************************************************/
+
+bool weak_function arm_should_generate_nonsecure_busfault(void)
+{
+  return true;
+}
+
 /****************************************************************************
  * Name: arm_securefault
  *
@@ -112,7 +157,16 @@ int arm_securefault(int irq, FAR void *context, FAR void *arg)
 
   putreg32(0xff, SAU_SFSR);
 
+#ifdef CONFIG_DEBUG_SECUREFAULT
+  if (arm_should_generate_nonsecure_busfault())
+    {
+      generate_nonsecure_busfault();
+      return OK;
+    }
+#endif
+
   up_irq_save();
   PANIC();
+
   return OK;
 }