From 6e8cc9d56cc32c607db0cc83e3d93cf366ef4e13 Mon Sep 17 00:00:00 2001
From: Tim Newsome <tim@casualhacker.net>
Date: Thu, 22 Aug 2024 09:51:45 -0700
Subject: [PATCH] Only implement tcontrol to handle reentrant triggers.

The spec says to only implement a single option. Option 2 gives software
more flexibility, and we already have an implementation. Let's use that
one. See also #1777.
---
 riscv/triggers.cc | 23 ++++-------------------
 riscv/triggers.h  |  1 -
 2 files changed, 4 insertions(+), 20 deletions(-)

diff --git a/riscv/triggers.cc b/riscv/triggers.cc
index 9eac9684e1..9e2cffa755 100644
--- a/riscv/triggers.cc
+++ b/riscv/triggers.cc
@@ -110,21 +110,6 @@ bool trigger_t::textra_match(processor_t * const proc) const noexcept
   return true;
 }
 
-bool trigger_t::allow_action(const state_t * const state) const
-{
-  if (get_action() == ACTION_DEBUG_EXCEPTION) {
-    const bool mstatus_mie = state->mstatus->read() & MSTATUS_MIE;
-    const bool sstatus_sie = state->sstatus->read() & MSTATUS_SIE;
-    const bool vsstatus_sie = state->vsstatus->read() & MSTATUS_SIE;
-    const bool medeleg_breakpoint = (state->medeleg->read() >> CAUSE_BREAKPOINT) & 1;
-    const bool hedeleg_breakpoint = (state->hedeleg->read() >> CAUSE_BREAKPOINT) & 1;
-    return (state->prv != PRV_M || mstatus_mie) &&
-           (state->prv != PRV_S || state->v || !medeleg_breakpoint || sstatus_sie) &&
-           (state->prv != PRV_S || !state->v || !medeleg_breakpoint || !hedeleg_breakpoint || vsstatus_sie);
-  }
-  return true;
-}
-
 reg_t disabled_trigger_t::tdata1_read(const processor_t * const proc) const noexcept
 {
   auto xlen = proc->get_xlen();
@@ -235,7 +220,7 @@ std::optional<match_result_t> mcontrol_common_t::detect_memory_access_match(proc
     value &= 0xffffffff;
   }
 
-  if (simple_match(xlen, value) && allow_action(proc->get_state())) {
+  if (simple_match(xlen, value)) {
     /* This is OK because this function is only called if the trigger was not
      * inhibited by the previous trigger in the chain. */
     set_hit(timing ? HIT_IMMEDIATELY_AFTER : HIT_BEFORE);
@@ -316,7 +301,7 @@ void mcontrol6_t::tdata1_write(processor_t * const proc, const reg_t val, const
 
 std::optional<match_result_t> icount_t::detect_icount_fire(processor_t * const proc) noexcept
 {
-  if (!common_match(proc) || !allow_action(proc->get_state()))
+  if (!common_match(proc))
     return std::nullopt;
 
   std::optional<match_result_t> ret = std::nullopt;
@@ -331,7 +316,7 @@ std::optional<match_result_t> icount_t::detect_icount_fire(processor_t * const p
 
 void icount_t::detect_icount_decrement(processor_t * const proc) noexcept
 {
-  if (!common_match(proc) || !allow_action(proc->get_state()))
+  if (!common_match(proc))
     return;
 
   if (count >= 1) {
@@ -423,7 +408,7 @@ std::optional<match_result_t> trap_common_t::detect_trap_match(processor_t * con
   bool interrupt = (t.cause() & ((reg_t)1 << (xlen - 1))) != 0;
   reg_t bit = t.cause() & ~((reg_t)1 << (xlen - 1));
   assert(bit < xlen);
-  if (simple_match(interrupt, bit) && allow_action(proc->get_state())) {
+  if (simple_match(interrupt, bit)) {
     hit = true;
     return match_result_t(TIMING_AFTER, action);
   }
diff --git a/riscv/triggers.h b/riscv/triggers.h
index 24f920630d..9fba77d566 100644
--- a/riscv/triggers.h
+++ b/riscv/triggers.h
@@ -99,7 +99,6 @@ 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, bool use_prev_prv = false) const noexcept;
-  bool allow_action(const state_t * const state) const;
   reg_t tdata2;
 
   bool vs = false;