bugfix in raising accelerator interrupts

hwacha/hwacha.cc

@@ -103,5 +103,5 @@ void hwacha_t::take_exception(reg_t c, reg_t a)
   cause = c;
   aux = a;
   raise_interrupt();
-  throw std::logic_error("a hwacha exception was posted, but interrupts are disabled!");
+  throw std::logic_error("unreachable!");
 }

riscv/extension.cc

@@ -12,7 +12,14 @@ void extension_t::illegal_instruction()
 
 void extension_t::raise_interrupt()
 {
-  p->raise_interrupt(IRQ_COP);
+  int priv = get_field(p->get_state()->mstatus, MSTATUS_PRV);
+  int ie = get_field(p->get_state()->mstatus, MSTATUS_IE);
+
+  if (priv < PRV_M || (priv == PRV_M && ie)) {
+    p->raise_interrupt(IRQ_COP);
+  }
+
+  throw std::logic_error("a COP exception was posted, but interrupts are disabled!");
 }
 
 void extension_t::clear_interrupt()