| Subject | Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention | From | Ricardo Neri <> | Date | Wed, 08 Mar 2017 16:46:39 -0800 |
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On Wed, 2017-03-08 at 17:08 +0300, Stas Sergeev 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. > Yes, this is the case. > But at least in the past there was an attempt to > support SLDT as it is used by an ancient pharlap > DOS extender (currently unsupported by dosemu1/2). > So how difficult would it be to add an optional > possibility of delivering such SIGSEGV to userspace > so that the kernel's dummy emulation can be overridden?
I suppose a umip=noemulation kernel parameter could be added in this case.
> It doesn't need to be a matter of this particular > patch set, i.e. this proposal should not trigger a > v7 resend of all 21 patches. :) But it would be useful > for the future development of dosemu2.
Would dosemu2 use 32-bit processes in order to keep segmentation? If it could use 64-bit processes, emulation is not used in this case and the SIGSEGV is delivered to user space.
Thanks and BR, Ricardo
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