Merge pull request #1350 from rivosinc/etrigger_fix_exception_match

triggers: Fix etrigger match on exceptions

riscv/processor.cc

@@ -196,8 +196,8 @@ void state_t::reset(processor_t* const proc, reg_t max_isa)
   // mstatus_csr_t::unlogged_write()):
   auto xlen = proc->get_isa().get_max_xlen();
 
-  prv = PRV_M;
-  v = false;
+  prv = prev_prv = PRV_M;
+  v = prev_v = false;
   csrmap[CSR_MISA] = misa = std::make_shared<misa_csr_t>(proc, CSR_MISA, max_isa);
   mstatus = std::make_shared<mstatus_csr_t>(proc, CSR_MSTATUS);
 
@@ -717,6 +717,7 @@ reg_t processor_t::legalize_privilege(reg_t prv)
 void processor_t::set_privilege(reg_t prv)
 {
   mmu->flush_tlb();
+  state.prev_prv = state.prv;
   state.prv = legalize_privilege(prv);
 }
 
@@ -747,17 +748,16 @@ void processor_t::set_virt(bool virt)
   if (state.prv == PRV_M)
     return;
 
-  if (state.v != virt) {
-    /*
-     * Ideally, we should flush TLB here but we don't need it because
-     * set_virt() is always used in conjucter with set_privilege() and
-     * set_privilege() will flush TLB unconditionally.
-     *
-     * The virtualized sstatus register also relies on this TLB flush,
-     * since changing V might change sstatus.MXR and sstatus.SUM.
-     */
-    state.v = virt;
-  }
+  /*
+    * Ideally, we should flush TLB here but we don't need it because
+    * set_virt() is always used in conjucter with set_privilege() and
+    * set_privilege() will flush TLB unconditionally.
+    *
+    * The virtualized sstatus register also relies on this TLB flush,
+    * since changing V might change sstatus.MXR and sstatus.SUM.
+    */
+  state.prev_v = state.v;
+  state.v = virt;
 }
 
 void processor_t::enter_debug_mode(uint8_t cause)

riscv/processor.h

@@ -83,7 +83,9 @@ struct state_t
   // control and status registers
   std::unordered_map<reg_t, csr_t_p> csrmap;
   reg_t prv;    // TODO: Can this be an enum instead?
+  reg_t prev_prv;
   bool v;
+  bool prev_v;
   misa_csr_t_p misa;
   mstatus_csr_t_p mstatus;
   csr_t_p mstatush;

riscv/triggers.cc

@@ -55,16 +55,19 @@ 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);
 }
 
-bool trigger_t::common_match(processor_t * const proc) const noexcept {
-  return mode_match(proc->get_state()) && textra_match(proc);
+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;
+  return mode_match(prv, v) && textra_match(proc);
 }
 
-bool trigger_t::mode_match(state_t * const state) const noexcept
+bool trigger_t::mode_match(reg_t prv, bool v) const noexcept
 {
-  switch (state->prv) {
+  switch (prv) {
     case PRV_M: return m;
-    case PRV_S: return state->v ? vs : s;
-    case PRV_U: return state->v ? vu : u;
+    case PRV_S: return v ? vs : s;
+    case PRV_U: return v ? vu : u;
     default: assert(false);
   }
 }
@@ -397,7 +400,8 @@ void itrigger_t::tdata1_write(processor_t * const proc, const reg_t val, const b
 
 std::optional<match_result_t> trap_common_t::detect_trap_match(processor_t * const proc, const trap_t& t) noexcept
 {
-  if (!common_match(proc))
+  // Use the previous privilege for matching
+  if (!common_match(proc, true))
     return std::nullopt;
 
   auto xlen = proc->get_xlen();

riscv/triggers.h

@@ -90,7 +90,7 @@ class trigger_t {
 
 protected:
   static action_t legalize_action(reg_t val, reg_t action_mask, reg_t dmode_mask) noexcept;
-  bool common_match(processor_t * const proc) const noexcept;
+  bool common_match(processor_t * const proc, bool use_prev_prv = false) const noexcept;
   bool allow_action(const state_t * const state) const;
   reg_t tdata2;
 
@@ -102,7 +102,7 @@ class trigger_t {
 
 private:
   unsigned legalize_mhselect(bool h_enabled) const noexcept;
-  bool mode_match(state_t * const state) const noexcept;
+  bool mode_match(reg_t prv, bool v) const noexcept;
   bool textra_match(processor_t * const proc) const noexcept;
 
   struct mhselect_interpretation {