[rocket] only write badaddr on certain exceptions

rocket/src/main/scala/util.scala

@@ -49,6 +49,12 @@ object Util {
 
   def minUInt(first: UInt, rest: UInt*): UInt =
     minUInt(first +: rest.toSeq)
+
+  implicit class UIntIsOneOf(val x: UInt) extends AnyVal {
+    def isOneOf(s: Seq[UInt]): Bool = s.map(x === _).reduce(_||_)
+
+    def isOneOf(u1: UInt, u2: UInt*): Bool = isOneOf(u1 +: u2.toSeq)
+  }
 }
 
 import Util._