Hi Sebastian,
The Valgrind bugtracker also contains three patches I proposed back then. I was hoping that this would speed up the process of getting this fixed, but unfortunately it didn't help much. At many places Valgrind does not yet handle signal registers correctly and doesn't complain - except here, which is really unfortunate because even ignoring would be sufficient to make Wine happy.
Sorry this fell through the cracks. One underlying problem is that, some time back in 2003, I learnt just enough about x86 segment stuff to hack up what's currently in Valgrind, and then promptly forgot about it. So I'm not in much of a position to make an informed judgement now.
That said .. I would be OK with a partial fix which improves Valgrind's SS handling enough to make Wine work, so long as it doesn't create a situation where other cases are silently handled incorrectly. That is, if the fix only moves forwards on the correctness scale, and doesn't introduce any regressions.
On rereading https://bugs.kde.org/show_bug.cgi?id=344139#c1 I see that you have a candidate patch (http://ix.io/gKt, "Correctly handle the SS prefix when explicitly specified.") which appears to have the abovementioned properties. Is that correct?
J