fix(debug): hardware watchpoints, signal stops and breakpoint restore

Assisted-by: GLM 5.3

debug/display_linux_amd64.go

@@ -73,9 +73,29 @@ func decodeRflags(f uint64) string {
 	return flags[:len(flags)-1]
 }
 
-// archReturnAddr reads the return address from the stack (amd64 ABI0 convention).
+// archReturnAddr reads the return address of the current frame (amd64
+// ABI0 convention).  A function that contains a CALL (or has a frame) is
+// assembled with the prologue PUSHQ BP; MOVQ SP, BP, so mid-function the
+// word at SP is the saved caller BP, a stack address, and the return
+// address sits further up.  Walk the stack from SP and take the first word
+// that lies in an executable mapping: stack and data words never do, a
+// return address always does.
 func archReturnAddr(s *Session, regs *Regs) (uint64, error) {
-	return s.Peek(regs.GetSP())
+	ranges := execRanges(s.pid)
+	for off := uint64(0); off < 512; off += 8 {
+		word, err := s.Peek(regs.RSP + off)
+		if err != nil {
+			break
+		}
+		for _, r := range ranges {
+			if word >= r.lo && word < r.hi {
+				return word, nil
+			}
+		}
+	}
+	// No mapping available or nothing code-like on the stack: fall back to
+	// the raw entry convention, [SP] before any push.
+	return s.Peek(regs.RSP)
 }
 
 // archSPLabel returns the SP register name for display.