Messages in this thread | | | Subject | Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention | From | Stas Sergeev <> | Date | Fri, 10 Mar 2017 14:33:53 +0300 |
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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.
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