bsps/powerpc: Add PPC_EXC_CONFIG_USE_FIXED_HANDLER

In case a BSP enables this option, then fixed high level exception
handler will be used.  For normal asynchronous exceptions this is
bsp_interrupt_dispatch() and for other exceptions this is the handler
from the read-only ppc_exc_handler_table.  The global handler is
C_exception_handler().  This avoids some dependencies on valid
read-write data.

1 files changed, 15 insertions, 3 deletions

diff --git a/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c b/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c
index 25d6b26faa..b24467b8e9 100644
--- a/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c
+++ b/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_hdl.c
@@ -39,16 +39,22 @@ uint32_t ppc_exc_vector_register_mchk = 0;
  */
 uint32_t ppc_exc_msr_bits = MSR_IR | MSR_DR | MSR_RI;
 
-static int ppc_exc_handler_default(BSP_Exception_frame *f, unsigned int vector)
+int ppc_exc_handler_default(BSP_Exception_frame *f, unsigned int vector)
 {
   return -1;
 }
 
+#ifndef PPC_EXC_CONFIG_USE_FIXED_HANDLER
+
+exception_handler_t globalExceptHdl = C_exception_handler;
+
 /* Table of C-handlers */
 ppc_exc_handler_t ppc_exc_handler_table [LAST_VALID_EXC + 1] = {
   [0 ... LAST_VALID_EXC] = ppc_exc_handler_default
 };
 
+#endif /* PPC_EXC_CONFIG_USE_FIXED_HANDLER */
+
 ppc_exc_handler_t ppc_exc_get_handler(unsigned vector)
 {
   if (
@@ -65,9 +71,15 @@ rtems_status_code ppc_exc_set_handler(unsigned vector, ppc_exc_handler_t handler
 {
   if (vector <= LAST_VALID_EXC) {
     if (handler == NULL) {
-      ppc_exc_handler_table [vector] = ppc_exc_handler_default;
-    } else {
+      handler = ppc_exc_handler_default;
+    }
+
+    if (ppc_exc_handler_table [vector] != handler) {
+#ifndef PPC_EXC_CONFIG_USE_FIXED_HANDLER
       ppc_exc_handler_table [vector] = handler;
+#else /* PPC_EXC_CONFIG_USE_FIXED_HANDLER */
+      return RTEMS_RESOURCE_IN_USE;
+#endif /* PPC_EXC_CONFIG_USE_FIXED_HANDLER */
     }
 
     return RTEMS_SUCCESSFUL;