From 38e57ba3ba0f907270b57d8b6a17381681a76545 Mon Sep 17 00:00:00 2001
From: Parth <parth.sinha@webcurl.co.uk>
Date: Tue, 28 Jul 2026 10:44:50 +0100
Subject: [PATCH] Debug/Trace: stop execution when a timing-before trigger
 matches
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End the current processor step after taking the trigger action, preventing an extra debug-ROM or trap-handler
instruction from executing before the caller observes the matched instruction’s architectural context.
---
 riscv/execute.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/riscv/execute.cc b/riscv/execute.cc
index 97c90de1..8f30acaa 100644
--- a/riscv/execute.cc
+++ b/riscv/execute.cc
@@ -346,6 +346,10 @@ void processor_t::step(size_t n)
     catch (triggers::matched_t& t)
     {
       take_trigger_action(t.action, t.address, pc, t.gva);
+      // End this step at the trigger boundary.  In particular, a timing-before
+      // trigger retires no instruction, so continuing would immediately execute
+      // from the debug ROM or trap vector to consume the remaining step count.
+      n = instret;
     }
     catch(trap_debug_mode&)
     {