Firefox has its own linker on Android

While this is a really cool trick, I think it would be better to avoid using SIGSEGV, seeing as how it's already used sometimes by JIT vms such as the JVM (I'm not sure if ART does the same) to indicate branch misprediction and drop back to interpreted code from a compiled section.

It also won't play well with anything that tries to hook functions, since they'll pull in a NULL as the original function. Or does this work around that also?

It would be really cool to see this upstreamed to bionic. Firefox has always been really fast on android, especially when opening for the first time.