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Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests

From Borislav Petkov <bp@suse.de>
Newsgroups linux.kernel
Subject Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests
Date 2015-11-19 13:10 +0100
Message-ID <qwwci-Gn-13@gated-at.bofh.it> (permalink)
References <qwhdg-7Lc-9@gated-at.bofh.it> <qwhdg-7Lc-29@gated-at.bofh.it> <qwhwC-7V2-33@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, Nov 18, 2015 at 12:21:56PM -0800, Andy Lutomirski wrote:
> Could we make this a little less subtle:
> 
> ALTERNATIVE "testl %eax, %eax; lz .Lsyscall_32_done", "jmp
> .Lsyscasll_32_done", X86_FEATURE_XENPV
> 
> Borislav, what do you think?

I don't mind either.

I would've said your version doesn't touch %eax so the result in there
might be useful for callers but all paths do overwrite it, AFAICT.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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Thread

[PATCH 0/3] Fix and cleanup for 32-bit PV sysexit Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-18 21:10 +0100
  [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-18 21:10 +0100
    Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Andy Lutomirski <luto@amacapital.net> - 2015-11-18 21:30 +0100
      Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Borislav Petkov <bp@suse.de> - 2015-11-18 21:50 +0100
      Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Brian Gerst <brgerst@gmail.com> - 2015-11-18 22:00 +0100
        Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Andy Lutomirski <luto@amacapital.net> - 2015-11-18 22:00 +0100
          Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-18 23:10 +0100
      Re: [PATCH 1/3] x86/xen: Avoid fast syscall path for Xen PV guests Borislav Petkov <bp@suse.de> - 2015-11-19 13:10 +0100
  Re: [PATCH 0/3] Fix and cleanup for 32-bit PV sysexit Borislav Petkov <bp@suse.de> - 2015-11-19 13:20 +0100

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