Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now

From	Ingo Molnar <mingo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now
Date	2016-01-12 11:50 +0100
Message-ID	<qQ4Gu-8a9-19@gated-at.bofh.it> (permalink)
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* Andy Lutomirski <luto@amacapital.net> wrote:

> On Mon, Jan 11, 2016 at 2:59 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Shuah Khan <shuahkh@osg.samsung.com> wrote:
> >
> >> On 01/06/2016 12:51 PM, Andy Lutomirski wrote:
> >> > ldt_gdt.c relies on cross-cpu invalidation of SS to do one of its
> >> > tests.  On 32-bit builds, this works fine, but on 64-bit builds, it
> >> > only works if the kernel has proper SS sigcontext handling for
> >> > 64-bit user programs.
> >> >
> >> > Since the SS fixes are currently reverted, restrict the test case to
> >> > 32 bits for now.
> >> >
> >> > In principle, I could change the test to use a different segment
> >> > register, but it would be messy: CS can't point to the LDT for
> >> > 64-bit code, and the other registers don't result in immediate
> >> > faults because they aren't reloaded on kernel -> user transitions.
> >> >
> >> > When we fix sigcontext (in 4.6?), we can revert this.
> >> >
> >> > Signed-off-by: Andy Lutomirski <luto@kernel.org>
> >> > --
> >>
> >> Andy,
> >>
> >> This patch didn't apply to linux-kselftest next.
> >> It probably has to go through x86.
> >
> > It doesn't apply to -tip either. Andy, which tree is this against?
> 
> Oops, it applies on top of a new self-test that I forgot to send.  I
> send a v2 that should be better.  I'll send the new selftest out as
> well once -tip catches up with all the vdso patches.

Ok, sounds great!

Thanks,

	Ingo

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[PATCH] selftests/x86: Disable ldt_gdt_64 for now Andy Lutomirski <luto@kernel.org> - 2016-01-06 21:00 +0100
  Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now Shuah Khan <shuahkh@osg.samsung.com> - 2016-01-07 21:50 +0100
    Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now Ingo Molnar <mingo@kernel.org> - 2016-01-11 12:00 +0100
      Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now Andy Lutomirski <luto@amacapital.net> - 2016-01-12 02:30 +0100
        Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now Ingo Molnar <mingo@kernel.org> - 2016-01-12 11:50 +0100

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