It used to look like this:
http://git.savannah.gnu.org/gitweb/?p=libunwind.git;a=commitdiff;h=92cc7fd78a5a79c4bb5f85bfb7d7fb025df9cd5a
Hmm, that's not too bad, but a long stretch from pretty ;-)
How would you 'encode' this in the perf callchain data?
These days we just look at dwarf augmentation string:
http://git.savannah.gnu.org/gitweb/?p=libunwind.git;a=blob;f=src/dwarf/Gfde.c;h=8659624b0320c514057861a259b6efe1b605bbf3;hb=HEAD#l189
Right, except of course we don't have that in kernel..