Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 22 Mar 2018 01:40:38 +0000 | Subject | Re: [PATCH 14/15] x86/fsgsbase/64: Support legacy behavior when FS/GS updated by ptracer |
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On Wed, Mar 21, 2018 at 3:11 PM, Bae, Chang Seok <chang.seok.bae@intel.com> wrote: > On 3/20/18, 17:47, "Andy Lutomirski" <luto@kernel.org> wrote: >> If I've understood all your emails right, when you looked at existing >> ptrace users, you found that all of them that write to gs and/or >> gs_base do it as part of a putregs call that writes them at the same >> time. If so, then your patch does exactly the same thing that my old >> patches did, but your patch is much more complicated. So why did you >> add all that complexity? > > What is tried to be provided is backward compatibility by emulating > “mov gs (fs) …” when index is only changed and preserve a (given) base value > in other cases.
mov to gs changes GSBASE even if GS was unchanged.
But it's not clear to me that you've identified any case where emulating this behavior is useful.
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