Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1362199

Re: Updated version of RD/WR FS/GS BASE patchkit

From Andi Kleen <andi@firstfloor.org>
Newsgroups linux.kernel
Subject Re: Updated version of RD/WR FS/GS BASE patchkit
Date 2016-03-22 00:00 +0100
Message-ID <rfgXM-3Lu-11@gated-at.bofh.it> (permalink)
References (5 earlier) <rfgbn-3qY-5@gated-at.bofh.it> <rfgl4-3uK-21@gated-at.bofh.it> <rfguK-3zz-15@gated-at.bofh.it> <rfgO6-3If-27@gated-at.bofh.it> <rfgO7-3If-37@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

> No.  My objection is that there needs to be an explicit statement what
> the semantics are.  If the agreed-upon semantics are "undefined
> behavior if GS != 0 and GSBASE doesn't match the descriptor", so be
> it, but this needs to be a conscious decision and needs to be weighed
> against the alternatives.

Documentation/x86/fsgs.txt already has this statement:

>>>
Another requirement is that the FS or GS selector has to be zero
(is normally true unless changed explicitly). When it is non-zero
the context switch assumes the bases were loaded through the LDT/GDT,
and will reload that.
<<<

Is that sufficient?

> 
> The actual implementation details are just details.  They need to
> match the intended semantics, of course.

I believe my implementation matches the paragraph above.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Updated version of RD/WR FS/GS BASE patchkit Andi Kleen <andi@firstfloor.org> - 2016-03-21 17:20 +0100
  Re: Updated version of RD/WR FS/GS BASE patchkit Andy Lutomirski <luto@amacapital.net> - 2016-03-21 20:30 +0100
    Re: Updated version of RD/WR FS/GS BASE patchkit Andi Kleen <andi@firstfloor.org> - 2016-03-21 20:50 +0100
      Re: Updated version of RD/WR FS/GS BASE patchkit Andy Lutomirski <luto@amacapital.net> - 2016-03-21 23:10 +0100
        Re: Updated version of RD/WR FS/GS BASE patchkit Andi Kleen <andi@firstfloor.org> - 2016-03-21 23:20 +0100
          Re: Updated version of RD/WR FS/GS BASE patchkit Andy Lutomirski <luto@amacapital.net> - 2016-03-21 23:30 +0100
            Re: Updated version of RD/WR FS/GS BASE patchkit Andi Kleen <andi@firstfloor.org> - 2016-03-21 23:50 +0100
              Re: Updated version of RD/WR FS/GS BASE patchkit Andy Lutomirski <luto@amacapital.net> - 2016-03-21 23:50 +0100
                Re: Updated version of RD/WR FS/GS BASE patchkit Andy Lutomirski <luto@amacapital.net> - 2016-03-22 00:00 +0100
                Re: Updated version of RD/WR FS/GS BASE patchkit Andi Kleen <andi@firstfloor.org> - 2016-03-22 00:10 +0100
                Re: Updated version of RD/WR FS/GS BASE patchkit Andi Kleen <andi@firstfloor.org> - 2016-03-22 00:00 +0100
  Re: Updated version of RD/WR FS/GS BASE patchkit Andi Kleen <andi@firstfloor.org> - 2016-03-21 20:30 +0100
  Re: Updated version of RD/WR FS/GS BASE patchkit Andy Lutomirski <luto@amacapital.net> - 2016-03-21 20:50 +0100

csiph-web