Want DTrace probes for individual predicate matches

While getting ICMPv6 support off the ground, I spent a long time figuring out why a rule failed to match. Turns out I had the used wrong destination MAC address for OPTE in the guest: a8:40:25:f7:77:77 instead of the correct a8:40:25:ff:77:77. I used the opte-rule-match.d D script to verify that the rule indeed failed to match, but it would be extremely valuable to see exactly how each predicate in the rule matches (or not) against the data provided for it.

The real problem here was that the rule-match probe takes the FlowId and stringifies it, which includes the IP protocol, and source/destination IP addresses and ports, while the actual predicate that failed to match was on the destination MAC address. A probe named something like predicate-match would be very helpful, and could include the predicate kind; the data it was provided; the data it expected to find; and the boolean indicating whether it matched.

Start by reading the existing opte-rule-match.d D script and the rule-match probe it uses. Trace how predicate evaluation data is exposed, then make the requested predicate-level information available: predicate kind, provided data, expected data, and whether it matched; done means the probe can explain the destination-MAC mismatch described here.