Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls

From	Ingo Molnar <mingo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls
Date	2016-07-14 10:10 +0200
Message-ID	<rUJSz-6Yc-53@gated-at.bofh.it> (permalink)
References	(5 earlier) <rTKH0-8jQ-15@gated-at.bofh.it> <rTLD4-xi-21@gated-at.bofh.it> <rU8T0-7sL-11@gated-at.bofh.it> <rUnfj-8tL-1@gated-at.bofh.it> <rUxom-6SS-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

* Andy Lutomirski <luto@amacapital.net> wrote:

> On Wed, Jul 13, 2016 at 12:56 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Andy Lutomirski <luto@amacapital.net> wrote:
> >
> >> > If we push a PKRU value into a thread between the rdpkru() and wrpkru(), we'll
> >> > lose the content of that "push".  I'm not sure there's any way to guarantee
> >> > this with a user-controlled register.
> >>
> >> We could try to insist that user code uses some vsyscall helper that tracks
> >> which bits are as-yet-unassigned.  That's quite messy, though.
> >
> > Actually, if we turned the vDSO into something more like a minimal user-space 
> > library with the ability to run at process startup as well to prepare stuff 
> > then it's painful to get right only *once*, and there will be tons of other 
> > areas where a proper per thread data storage on the user-space side would be 
> > immensely useful!
> 
> Doing this could be tricky: how exactly is the vDSO supposed to find per-thread 
> data without breaking existing glibc?

So I think the way this could be done is by allocating it itself. The vDSO vma 
itself is 'external' to glibc as well to begin with - this would be a small 
extension to that concept.

Thanks,

	Ingo

Thread

Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Andy Lutomirski <luto@amacapital.net> - 2016-07-11 06:30 +0200
  Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Ingo Molnar <mingo@kernel.org> - 2016-07-11 09:40 +0200
    Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Dave Hansen <dave@sr71.net> - 2016-07-11 16:30 +0200
      Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Ingo Molnar <mingo@kernel.org> - 2016-07-12 09:20 +0200
        Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Dave Hansen <dave@sr71.net> - 2016-07-12 17:40 +0200
    Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Andy Lutomirski <luto@amacapital.net> - 2016-07-11 17:00 +0200
  Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Dave Hansen <dave@sr71.net> - 2016-07-11 16:40 +0200
    Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Andy Lutomirski <luto@amacapital.net> - 2016-07-11 16:50 +0200
      Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Dave Hansen <dave.hansen@intel.com> - 2016-07-11 17:50 +0200
        Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Andy Lutomirski <luto@amacapital.net> - 2016-07-12 18:40 +0200
          Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Dave Hansen <dave.hansen@intel.com> - 2016-07-12 19:20 +0200
            Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Andy Lutomirski <luto@amacapital.net> - 2016-07-13 01:00 +0200
          Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Ingo Molnar <mingo@kernel.org> - 2016-07-13 10:00 +0200
            Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Andy Lutomirski <luto@amacapital.net> - 2016-07-13 20:50 +0200
              Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Ingo Molnar <mingo@kernel.org> - 2016-07-14 10:10 +0200
                Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Andy Lutomirski <luto@amacapital.net> - 2016-07-18 06:50 +0200
                Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Ingo Molnar <mingo@kernel.org> - 2016-07-18 12:00 +0200

csiph-web