Groups > linux.kernel > #1519551

Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention definitions

From	Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention definitions
Date	2016-11-11 05:10 +0100
Message-ID	<sCbk5-7IZ-7@gated-at.bofh.it> (permalink)
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On Thu, 2016-11-10 at 09:58 +0100, Borislav Petkov wrote:
> On Wed, Nov 09, 2016 at 07:24:43PM -0800, Ricardo Neri wrote:
> > I intended this feature to be configurable at build time in case someone
> > wants to build a kernel without it; similar to other features such as
> > SMAP. Is this not needed? Should Linux be built with this feature always
> > enabled?
> > 
> > This feature could always be disabled via a kernel parameter, though;
> > even if Linux is built with it.
> 
> It probably is a good idea to have it build-time configurable for the
> embedded folks. But you can do a before and after build and look at
> the vmlinux size and see how much it has grown. If it is only a couple
> of KBs I guess we can drop the config option even but I know there are
> people who still care about KBs too...

Thanks for the suggestions. Perhaps I can include these metrics in my
V2. On th other hand, Dave Hansen gave a good argument on potential
conflicts when, of instance running on an AMD CPU. UMIP is enabled by
setting a bit in CR4. If that bit is not supposed to be set, that could
cause a #GP fault.

Thanks and BR,
Ricardo
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)

Thread

[PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention definitions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2016-11-08 07:20 +0100
  Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention definitions Andy Lutomirski <luto@amacapital.net> - 2016-11-08 16:40 +0100
    Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction  Prevention definitions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2016-11-09 05:30 +0100
      Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention definitions Andy Lutomirski <luto@amacapital.net> - 2016-11-09 12:50 +0100
        Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction  Prevention definitions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2016-11-10 04:30 +0100
          Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention  definitions Borislav Petkov <bp@suse.de> - 2016-11-10 10:00 +0100
            Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction  Prevention definitions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2016-11-11 05:10 +0100
              Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention  definitions Borislav Petkov <bp@suse.de> - 2016-11-11 11:30 +0100
                Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction  Prevention definitions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2016-11-12 02:30 +0100
              Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention  definitions Dave Hansen <dave.hansen@linux.intel.com> - 2016-11-11 19:10 +0100
          Re: [PATCH 1/4] x86/cpufeature: Add User-Mode Instruction Prevention  definitions Dave Hansen <dave.hansen@linux.intel.com> - 2016-11-10 18:10 +0100

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