Rusty did not like the __dot_sym approach and suggested instead:

1) make rem, urem, mul, umul, div and udiv aliases to .rem, .urem etc:

   extern int rem(int, int) __attribute__((weak,alias(".rem")));

2) EXPORT_SYMBOL(rem) etc.
3) Check genksyms recognises that prototype (it should).
4) Copy "dedotify" from ppc64 to handle them on load.

The only real downside is the risk that someone else will export
those names, but I think that's pretty unlikely.