On Thu, Jun 07, 2018 at 01:57:03PM -0700, Andy Lutomirski wrote: ... > > > > I didn't read the whole series of patches in details > > yet, hopefully will be able tomorrow. Thanks Andy for > > CC'ing! > > We have uc_flags. It might be useful to carve out some of the flag > space (24 bits?) to indicate something like the *size* of sigcontext > and teach the kernel that new sigcontext fields should only be parsed > on sigreturn() if the size is large enough. Yes, this should do the trick.