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Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention

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On Fri, 2017-03-10 at 14:33 +0300, Stas Sergeev wrote:
> 10.03.2017 05:39, Andy Lutomirski пишет:
> > On Thu, Mar 9, 2017 at 2:10 PM, Stas Sergeev <stsp@list.ru> wrote:
> >> 09.03.2017 04:15, Ricardo Neri пишет:
> >>
> >>> On Wed, 2017-03-08 at 08:46 -0800, Andy Lutomirski wrote:
> >>>> On Wed, Mar 8, 2017 at 8:29 AM, Stas Sergeev <stsp@list.ru> wrote:
> >>>>> 08.03.2017 19:06, Andy Lutomirski пишет:
> >>>>>> On Wed, Mar 8, 2017 at 6:08 AM, Stas Sergeev <stsp@list.ru> wrote:
> >>>>>>> 08.03.2017 03:32, Ricardo Neri пишет:
> >>>>>>>> These are the instructions covered by UMIP:
> >>>>>>>> * SGDT - Store Global Descriptor Table
> >>>>>>>> * SIDT - Store Interrupt Descriptor Table
> >>>>>>>> * SLDT - Store Local Descriptor Table
> >>>>>>>> * SMSW - Store Machine Status Word
> >>>>>>>> * STR - Store Task Register
> >>>>>>>>
> >>>>>>>> This patchset initially treated tasks running in virtual-8086
> >>>> mode as a
> >>>>>>>> special case. However, I received clarification that DOSEMU[8]
> >>>> does not
> >>>>>>>> support applications that use these instructions.
> >>>>>> Can you remind me what was special about it?  It looks like you
> >>>> still
> >>>>>> emulate them in v8086 mode.
> >>>>> Indeed, sorry, I meant prot mode here. :)
> >>>>> So I wonder what was cited to be special about v86.
> >>> Initially my patches disabled UMIP on virtual-8086 instructions, without
> >>> regards of protected mode (i.e., UMIP was always enabled). I didn't have
> >>> emulation at the time. Then, I added emulation code that now covers
> >>> protected and virtual-8086 modes. I guess it is not special anymore.
> >> But isn't SLDT&friends just throw UD in v86?
> >> How does UMIP affect this? How does your patch affect
> >> this?
> > Er, right.  Ricardo, your code may need fixing.  But don't you have a
> > test case for this?
> Why would you need one?
> Or do you really want to allow these instructions
> in v86 by the means of emulation? If so - this wasn't
> clearly stated in the patch description, neither it was
> properly discussed, it seems.

It str and sldt can be emulated in vm86 but as Andy mention, the
behavior sould be the same with and without emulation.

Thanks and BR,
Ricardo

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[v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 09/21] x86/insn-eval: Add functions to get default operand and address sizes Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 03/21] x86/mpx: Do not use R/EBP as base in the SIB byte with Mod = 0 Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 08/21] x86/insn-eval: Add utility function to get segment descriptor base address Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 15/21] x86/mm: Relocate page fault error codes to traps.h Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
    Re: [v6 PATCH 15/21] x86/mm: Relocate page fault error codes to traps.h Andy Lutomirski <luto@amacapital.net> - 2017-03-08 17:10 +0100
  [v6 PATCH 11/21] insn/eval: Incorporate segment base in address computation Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 16/21] x86/cpufeature: Add User-Mode Instruction Prevention definitions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 21/21] selftests/x86: Add tests for User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
    Re: [v6 PATCH 21/21] selftests/x86: Add tests for User-Mode  Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-08 17:30 +0100
      Re: [v6 PATCH 21/21] selftests/x86: Add tests for User-Mode  Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 00:40 +0100
  [v6 PATCH 01/21] x86/mpx: Use signed variables to compute effective addresses Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 20/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 13/21] x86/insn-eval: Add support to resolve 16-bit addressing encodings Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 17/21] x86: Add emulation code for UMIP instructions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 05/21] x86/insn-eval: Add utility functions to get register offsets Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 12/21] x86/insn: Support both signed 32-bit and 64-bit effective addresses Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 07/21] x86/insn-eval: Add utility function to get segment descriptor Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 18/21] x86/umip: Force a page fault when unable to copy emulated result to user Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 14/21] x86/insn-eval: Add wrapper function for 16-bit and 32-bit address encodings Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 06/21] x86/insn-eval: Add utility functions to get segment selector Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 02:00 +0100
  [v6 PATCH 02/21] x86/mpx: Do not use SIB index if index points to R/ESP Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 02:00 +0100
  [v6 PATCH 19/21] x86/traps: Fixup general protection faults caused by UMIP Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 02:00 +0100
    Re: [v6 PATCH 19/21] x86/traps: Fixup general protection faults  caused by UMIP Andy Lutomirski <luto@amacapital.net> - 2017-03-08 17:00 +0100
  [v6 PATCH 10/21] x86/insn-eval: Do not use R/EBP as base if mod in ModRM is zero Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 02:10 +0100
  [v6 PATCH 04/21] x86/mpx, x86/insn: Relocate insn util functions to a new insn-kernel Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 04:50 +0100
  Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-08 15:30 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-08 18:00 +0100
      Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-09 02:20 +0100
        Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-09 23:10 +0100
        Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@kernel.org> - 2017-03-10 03:50 +0100
          Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-10 22:00 +0100
            Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-10 22:10 +0100
              Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-10 22:40 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-08 18:20 +0100
      Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-09 02:20 +0100
        Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-09 23:20 +0100
          Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-10 03:50 +0100
            Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-10 12:40 +0100
              Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-10 15:20 +0100
                Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 02:30 +0100
              Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 01:10 +0100
            Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 01:00 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-08 23:30 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-08 23:50 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-09 02:50 +0100
      Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-10 02:30 +0100
        Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 00:50 +0100
          Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-11 01:00 +0100
            Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 01:20 +0100
  Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-08 17:20 +0100

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