I concocted a test case that was independent from ghc, confirmed it still reproduced with current binutils git and filed an upstream bug: https://sourceware.org/bugzilla/show_bug.cgi?id=26902. I even made a little patch that fixes the problem but I don't know if it's in any way correct.
- Bug#973623: stack overflows with ghc on ppc64el Steve Langasek
- Bug#973623: Michael Hudson-Doyle
- Bug#973623: stack overflows with ghc on ppc64el Matthias Klose
- Bug#973623: stack overflows with ghc on ppc6... Michael Hudson-Doyle
- Bug#973623: Michael Hudson-Doyle
