microblaze: Trap on bus accesses to unmapped areas.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
diff --git a/target-microblaze/op_helper.c b/target-microblaze/op_helper.c
index a5b3827..2cc4ced 100644
--- a/target-microblaze/op_helper.c
+++ b/target-microblaze/op_helper.c
@@ -245,3 +245,30 @@
     mmu_write(env, rn, v);
 }
 #endif
+
+void do_unassigned_access(target_phys_addr_t addr, int is_write, int is_exec,
+                          int is_asi, int size)
+{
+    CPUState *saved_env;
+    /* XXX: hack to restore env in all cases, even if not called from
+       generated code */
+    saved_env = env;
+    env = cpu_single_env;
+    qemu_log("Unassigned " TARGET_FMT_plx " wr=%d exe=%d\n",
+             addr, is_write, is_exec);
+    if (!(env->sregs[SR_MSR] & MSR_EE)) {
+        return;
+    }
+
+    if (is_exec) {
+        if (!(env->pvr.regs[2] & PVR2_IOPB_BUS_EXC_MASK)) {
+            env->sregs[SR_ESR] = ESR_EC_INSN_BUS;
+            helper_raise_exception(EXCP_HW_EXCP);
+        }
+    } else {
+        if (!(env->pvr.regs[2] & PVR2_DOPB_BUS_EXC_MASK)) {
+            env->sregs[SR_ESR] = ESR_EC_DATA_BUS;
+            helper_raise_exception(EXCP_HW_EXCP);
+        }
+    }
+}