Hi! Tavis noticed that on ARM kernels with CONFIG_BINFMT_ELF_FDPIC, it looks like the FDPIC_FUNCPTRS personality flag is not reset on execve(). This would mean that if a process first executes an ELF FDPIC binary (which forces the personality to PER_LINUX_FDPIC), and then executes a non-FDPIC binary, the signal handling code (setup_return()) will have bogus behavior (interpreting a normal function pointer as an FDPIC function handle).
I think FDPIC_FUNCPTRS should probably either be reset on every execve() or not be a personality flag at all (since AFAIU pretty much the whole point of personality flags is that they control behavior even across execve()). (I don't have an FDPIC toolchain, so I'm writing this solely based on having read the code, without having actually tested it.)
