triggers: add disabled_trigger_t

README.md

@@ -38,7 +38,7 @@ Spike supports the following RISC-V ISA features:
   - Svpbmt extension, v1.0
   - Svinval extension, v1.0
   - Debug v0.14
-    - 4 triggers fixed to type=2 (mcontrol)
+    - 4 triggers support type=2 (mcontrol) and type=15 (disabled)
   - Smepmp extension v1.0
   - Smstateen extension, v1.0
   - Sscofpmf v0.5.2

riscv/triggers.cc

@@ -13,6 +13,22 @@ void trigger_with_tdata2_t::tdata2_write(processor_t UNUSED * const proc, const
   tdata2 = val;
 }
 
+reg_t disabled_trigger_t::tdata1_read(const processor_t * const proc) const noexcept
+{
+  auto xlen = proc->get_xlen();
+  reg_t tdata1 = 0;
+  tdata1 = set_field(tdata1, CSR_TDATA1_TYPE(xlen), CSR_TDATA1_TYPE_DISABLED);
+  tdata1 = set_field(tdata1, CSR_TDATA1_DMODE(xlen), dmode);
+  return tdata1;
+}
+
+void disabled_trigger_t::tdata1_write(processor_t * const proc, const reg_t val) noexcept
+{
+  // Any supported tdata.type results in disabled trigger
+  auto xlen = proc->get_xlen();
+  dmode = proc->get_state()->debug_mode ? get_field(val, CSR_TDATA1_DMODE(xlen)) : 0;
+}
+
 reg_t mcontrol_t::tdata1_read(const processor_t * const proc) const noexcept {
   reg_t v = 0;
   auto xlen = proc->get_xlen();
@@ -182,7 +198,21 @@ bool module_t::tdata1_write(processor_t * const proc, unsigned index, const reg_
   if (triggers[index]->get_dmode() && !proc->get_state()->debug_mode) {
     return false;
   }
-  triggers[index]->tdata1_write(proc, val);
+
+  auto xlen = proc->get_xlen();
+
+  unsigned type = get_field(val, CSR_TDATA1_TYPE(xlen));
+  reg_t tdata1 = val;
+  reg_t tdata2 = triggers[index]->tdata2_read(proc);
+
+  delete triggers[index];
+  switch (type) {
+    case CSR_TDATA1_TYPE_MCONTROL: triggers[index] = new mcontrol_t(); break;
+    default: triggers[index] = new disabled_trigger_t(); break;
+  }
+
+  triggers[index]->tdata1_write(proc, tdata1);
+  triggers[index]->tdata2_write(proc, tdata2);
   proc->trigger_updated(triggers);
   return true;
 }
@@ -205,7 +235,7 @@ bool module_t::tdata2_write(processor_t * const proc, unsigned index, const reg_
 reg_t module_t::tinfo_read(UNUSED const processor_t * const proc, unsigned UNUSED index) const noexcept
 {
   /* In spike, every trigger supports the same types. */
-  return 1<<MCONTROL_TYPE_MATCH;
+  return (1 << MCONTROL_TYPE_MATCH) | (1 << CSR_TDATA1_TYPE_DISABLED);
 }
 
 };

riscv/triggers.h

@@ -66,8 +66,8 @@ public:
   virtual bool get_load() const { return false; }
   virtual action_t get_action() const { return ACTION_DEBUG_EXCEPTION; }
 
-  virtual match_result_t memory_access_match(processor_t * const proc,
-      operation_t operation, reg_t address, std::optional<reg_t> data) = 0;
+  virtual match_result_t memory_access_match(processor_t UNUSED * const proc,
+      operation_t UNUSED operation, reg_t UNUSED address, std::optional<reg_t> UNUSED data) { return match_result_t(false); }
 };
 
 class trigger_with_tdata2_t : public trigger_t {
@@ -79,6 +79,17 @@ protected:
   reg_t tdata2;
 };
 
+class disabled_trigger_t : public trigger_with_tdata2_t {
+public:
+  virtual reg_t tdata1_read(const processor_t * const proc) const noexcept override;
+  virtual void tdata1_write(processor_t * const proc, const reg_t val) noexcept override;
+
+  virtual bool get_dmode() const override { return dmode; }
+
+private:
+  bool dmode;
+};
+
 class mcontrol_t : public trigger_with_tdata2_t {
 public:
   typedef enum