On Thu, Aug 13, 2015 at 9:19 AM, Linus Torvalds <torva...@linux-foundation.org> wrote: > On Thu, Aug 13, 2015 at 8:43 AM, Andy Lutomirski <l...@amacapital.net> wrote: >> >> I'm trying to fix it without reverting. If that doesn't work, then we >> revert. Yesterday, I thought I had a reasonably clean fix, but it >> turned out that it only solved half of the problem. > > The thing is, I actually think that the current situation is crazy. > > Especially given that we don't restore any of the other segment > registers on x86-64 (except CS, of course) > > So how about this "alternate" minimal patch instead. The difference is: > > - we actually leave the > > regs->ss = __USER_DS; > > in __setup_rt_frame, to guarantee that when we take a signal, we do > take it with a valid SS
That by itself is enough to break DOSEMU. I think we may be stuck with my hack to only replace regs->ss if the old one was invalid. > > - but it removes all the other games with SS (and treats it exactly > the same as FS/GS). > > So now we don't play games with the actual sigcontext, and > hopefully dosemu is happier. You mean that we always set ss to __USER_DS on sigreturn? The problem is that user code *can't* program SS when calling sigreturn because the SYSCALL instruction zaps it. I'll try to implement something. If this regression were new in 4.2-rc, then I'd say revert first and ask questions later, but the regression is in 4.1 as well :( --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
