Work if tcontrol doesn't exist.

Author: rtwfroody

riscv/insns/mret.h

@@ -20,5 +20,5 @@ if (prev_virt && prev_prv == PRV_U)
   STATE.vsstatus->write(STATE.vsstatus->read() & ~SSTATUS_SDT);
 STATE.mstatus->write(s);
 if (STATE.mstatush) STATE.mstatush->write(s >> 32); // log mstatush change
-STATE.tcontrol->write((STATE.tcontrol->read() & CSR_TCONTROL_MPTE) ? (CSR_TCONTROL_MPTE | CSR_TCONTROL_MTE) : 0);
+if (STATE.tcontrol) STATE.tcontrol->write((STATE.tcontrol->read() & CSR_TCONTROL_MPTE) ? (CSR_TCONTROL_MPTE | CSR_TCONTROL_MTE) : 0);
 p->set_privilege(prev_prv, prev_virt);

riscv/processor.cc

@@ -535,7 +535,7 @@ void processor_t::take_trap(trap_t& t, reg_t epc)
     state.elp = elp_t::NO_LP_EXPECTED;
     state.mstatus->write(s);
     if (state.mstatush) state.mstatush->write(s >> 32);  // log mstatush change
-    state.tcontrol->write((state.tcontrol->read() & CSR_TCONTROL_MTE) ? CSR_TCONTROL_MPTE : 0);
+    if (state.tcontrol) state.tcontrol->write((state.tcontrol->read() & CSR_TCONTROL_MTE) ? CSR_TCONTROL_MPTE : 0);
     set_privilege(PRV_M, false);
   }
 }

riscv/triggers.cc

@@ -55,11 +55,18 @@ void trigger_t::tdata3_write(processor_t * const proc, const reg_t val) noexcept
   sselect = (sselect_t)((proc->extension_enabled_const('S') && get_field(val, CSR_TEXTRA_SSELECT(xlen)) <= SSELECT_MAXVAL) ? get_field(val, CSR_TEXTRA_SSELECT(xlen)) : SSELECT_IGNORE);
 }
 
+static reg_t tcontrol_value(const state_t * state) {
+  if (state->tcontrol)
+    return state->tcontrol->read();
+  else
+    return 0;
+}
+
 bool trigger_t::common_match(processor_t * const proc, bool use_prev_prv) const noexcept {
   auto state = proc->get_state();
   auto prv = use_prev_prv ? state->prev_prv : state->prv;
   auto v = use_prev_prv ? state->prev_v : state->v;
-  auto m_enabled = get_action() != 0 || (state->tcontrol->read() & CSR_TCONTROL_MTE);
+  auto m_enabled = get_action() != 0 || (tcontrol_value(state) & CSR_TCONTROL_MTE);
   return (prv < PRV_M || m_enabled) && mode_match(prv, v) && textra_match(proc);
 }