From f405cea5bc29fa6628d0783a8ca58bfb901b0f9a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20Balv=C3=ADn?= <opensource@petrbalvin.org>
Date: Fri, 2 Oct 2026 00:40:54 +0200
Subject: [PATCH] fix(cmd): stop the coverage run on a stray in-place trap

Assisted-by: GLM 5.3
---
 cmd/gasm/debug_ptrace.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/cmd/gasm/debug_ptrace.go b/cmd/gasm/debug_ptrace.go
index 4316d56..28f3c68 100644
--- a/cmd/gasm/debug_ptrace.go
+++ b/cmd/gasm/debug_ptrace.go
@@ -239,10 +239,12 @@ REPL commands:
 				fmt.Printf("gasm debug: cover: stopped on signal %v\n", sig)
 				break
 			}
+			reason, _ := sess.StopInfo()
 			regs, rerr := sess.GetRegs()
 			if rerr != nil {
 				break
 			}
+			trapPC := regs.GetPC()
 			// HandleTrap restores the original byte, rewinds PC and counts
 			// the hit on the breakpoint itself.  Single-step over the
 			// restored instruction so the reinsertion at the top of the
@@ -251,6 +253,12 @@ REPL commands:
 				if err := sess.Step(); err != nil {
 					break
 				}
+			} else if debug.TrapStray(sess, reason, trapPC) {
+				// A breakpoint-class trap that matches none of ours and left
+				// the PC in place: resuming would re-execute the trapping
+				// instruction forever, so the coverage run stops here.
+				fmt.Printf("gasm debug: cover: SIGTRAP at %#x matches no breakpoint; the PC did not advance\n", trapPC)
+				break
 			}
 		}
 		hits := map[uint64]int{}