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Re: [regression] x86/signal/64: Fix SS handling for signals delivered to 64-bit programs breaks dosemu

From Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups linux.kernel
Subject Re: [regression] x86/signal/64: Fix SS handling for signals delivered to 64-bit programs breaks dosemu
Date 2015-08-13 18:20 +0200
Message-ID <pX3ou-8pv-5@gated-at.bofh.it> (permalink)
References <pWrVU-4h9-5@gated-at.bofh.it> <pX2LL-7qM-5@gated-at.bofh.it> <pX2Vs-7C5-5@gated-at.bofh.it>
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On Thu, Aug 13, 2015 at 8:43 AM, Andy Lutomirski <luto@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

 - 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.

Hmm? That actually makes the code look better, and doesn't
re-introduce that annoying CONFIG_X86_32 case (because it now does it
in obviously the same place as fs/gs).

So the code is cleaner, and closer to what we used to do.

Stas, can you test this one too? I, like Luto, don't actually have a
dosemu test-case.

                      Linus

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Thread

[regression] x86/signal/64: Fix SS handling for signals delivered to  64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-12 02:20 +0200
  Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-12 02:40 +0200
    Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-12 10:30 +0200
      Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-12 18:20 +0200
        Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-12 19:10 +0200
          Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-12 20:30 +0200
            Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-12 21:00 +0200
              Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-12 21:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-12 22:00 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-12 22:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-12 22:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-12 22:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-12 22:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-12 23:00 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-12 23:40 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 00:00 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 00:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals  delivered to 64-bit programs breaks dosemu Ingo Molnar <mingo@kernel.org> - 2015-08-13 10:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 12:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 14:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 17:00 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 17:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 17:40 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 18:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 18:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 18:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 18:40 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 18:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 18:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 19:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 19:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 19:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 20:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 20:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 20:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 20:40 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 20:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 18:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 13:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-12 22:50 +0200
  Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 17:40 +0200
    Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 17:50 +0200
      Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 18:20 +0200
        Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 18:30 +0200
          Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 18:40 +0200
            Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 18:50 +0200
            Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 18:50 +0200
      Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Brian Gerst <brgerst@gmail.com> - 2015-08-13 19:10 +0200
        Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-18 08:40 +0200
          Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-19 00:50 +0200
            Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-19 11:40 +0200
              Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-19 17:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-19 18:40 +0200
          Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-19 00:50 +0200
            Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-19 12:20 +0200
              Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-19 17:40 +0200
      Re: [regression] x86/signal/64: Fix SS handling for signals  delivered to 64-bit programs breaks dosemu Cyrill Gorcunov <gorcunov@gmail.com> - 2015-08-14 10:20 +0200
    Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 20:00 +0200
      Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 20:40 +0200
        Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 20:50 +0200
          Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 21:10 +0200
            Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 21:50 +0200
              Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 22:20 +0200
          Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 22:00 +0200
            Re: [regression] x86/signal/64: Fix SS handling for signals  delivered to 64-bit programs breaks dosemu Cyrill Gorcunov <gorcunov@gmail.com> - 2015-08-13 22:10 +0200
              Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 22:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Raymond Jennings <shentino@gmail.com> - 2015-08-13 23:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 23:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Raymond Jennings <shentino@gmail.com> - 2015-08-14 00:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 00:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 01:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 01:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Raymond Jennings <shentino@gmail.com> - 2015-08-14 01:40 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 01:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 02:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 00:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-14 00:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 00:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-14 00:40 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 01:00 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-14 01:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 01:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-14 02:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 02:20 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 02:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 03:00 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-14 03:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-14 03:40 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 04:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-18 08:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 03:40 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 02:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-14 02:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-14 02:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-14 02:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals  delivered to 64-bit programs breaks dosemu Cyrill Gorcunov <gorcunov@gmail.com> - 2015-08-14 09:30 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Pavel Emelyanov <xemul@parallels.com> - 2015-08-14 12:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals  delivered to 64-bit programs breaks dosemu Cyrill Gorcunov <gorcunov@gmail.com> - 2015-08-14 13:00 +0200
        Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 21:00 +0200
          Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Andy Lutomirski <luto@amacapital.net> - 2015-08-13 21:10 +0200
            Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 21:20 +0200
              Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 21:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-13 22:10 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-18 08:50 +0200
                Re: [regression] x86/signal/64: Fix SS handling for signals delivered  to 64-bit programs breaks dosemu Stas Sergeev <stsp@list.ru> - 2015-08-13 22:10 +0200

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