On Fri, Apr 13, 2018 at 09:33:17AM -0700, Linus Torvalds wrote: > On Fri, Apr 13, 2018 at 2:42 AM, Russell King - ARM Linux > <li...@armlinux.org.uk> wrote: > > > > Yes, it does solve the problem at hand with strace - the exact patch I > > tested against 4.16 is below. > > Ok, good. > > > However, FPE_FLTUNK is not defined in older kernels, so while we can > > fix it this way for the current merge window, that doesn't help 4.16. > > I wonder if we should even bother with FPE_FLTUNK. > > I suspect we might as well use FPE_FLTINV, I suspect, and not have > this complexity at all. That case is not worth worrying about, since > it's a "this shouldn't happen anyway" and the *real* reason will be in > the kernel logs due to vfs_panic(). > > So it's not like this is something that the user should ever care > about the si_code about.
Ack, my intended meaning for FPE_FLTUNK is that the fp exception is either spurious or we can't tell easily (or possibly at all) which FPE_XXX should be returned. It's up to userspace to figure it out if it really cares. Previously we were accidentally returning SI_USER in si_code for arm64. This case on arm looks like a more serious error for which FPE_FLTINV may be more appropriate anyway. [...] Cheers ---Dave