Messages in this thread | | | Subject | Re: [PATCH] x86: Use entire page for the per-cpu GDT only if paravirt-enabled | From | "H. Peter Anvin" <> | Date | Tue, 29 Sep 2015 13:30:52 -0700 |
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On 09/29/2015 11:02 AM, Andy Lutomirski wrote: > On Tue, Sep 29, 2015 at 10:50 AM, Linus Torvalds > <torvalds@linux-foundation.org> wrote: >> On Tue, Sep 29, 2015 at 1:35 PM, Andy Lutomirski <luto@amacapital.net> wrote: >>> >>> Does anyone know what happens if you stick a non-accessed segment in >>> the GDT, map the GDT RO, and access it? >> >> You should get a #PF, as you guess, but go ahead and test it if you >> want to make sure. > > Then I think that, if we do this, the patch series should first make > it percpu and fixmapped but RW and then flip it RO as a separate patch > in case we need to revert the actual RO bit. I don't want to break > Wine or The Witcher 2 because of this, and we might need various > fixups. I really hope that no one uses get_thread_area to check > whether TLS has been accessed. >
Of course.
-hpa
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