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From: Jann Horn <jann@thejh.net>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Kyle Huey <me@kylehuey.com>, Thomas Gleixner <tglx@linutronix.de>,
	John Stultz <john.stultz@linaro.org>,
	Ingo Molnar <mingo@redhat.com>, Michal Hocko <mhocko@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	"Luis R. Rodriguez" <mcgrof@kernel.org>,
	Mateusz Guzik <mguzik@redhat.com>,
	Alex Thorlton <athorlton@sgi.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>,
	Jiri Slaby <jslaby@suse.cz>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Ben Segall <bsegall@google.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, Denys Vlasenko <dvlasenk@redhat.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	"Robert O'Callahan" <robert@ocallahan.org>,
	"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
	<linux-kernel@vger.kernel.org>, Juergen Gross <jgross@suse.com>,
	Linux API <linux-api@vger.kernel.org>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Kees Cook <keescook@chromium.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Borislav Petkov <bp@suse.de>, Len Brown <len.brown@intel.com>,
	Huang Rui <ray.huang@amd.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] prctl,x86 Add PR_[GET|SET]_CPUID for controlling the CPUID instruction.
Date: Mon, 12 Sep 2016 19:56:56 +0200	[thread overview]
Message-ID: <20160912175656.GA8935@laptop.thejh.net> (raw)
In-Reply-To: <CALCETrVJAib918qn9CL4Tvyfok-8eAHimYDabXUF=1Nsxo4-Pw@mail.gmail.com>

On Mon, Sep 12, 2016 at 09:56:11AM -0700, Andy Lutomirski wrote:
> On Sep 11, 2016 5:29 PM, "Kyle Huey" <me@kylehuey.com> wrote:
> >
> > rr (http://rr-project.org/), a userspace record-and-replay reverse-
> > execution debugger, would like to trap and emulate the CPUID instruction.
> > This would allow us to a) mask away certain hardware features that rr does
> > not support (e.g. RDRAND) and b) enable trace portability across machines
> > by providing constant results.
> >
> > Intel supports faulting on the CPUID instruction in newer processors. Bit
> > 31 of MSR_PLATFORM_INFO advertises support for this feature. It is
> > documented in detail in Section 2.3.2 of
> > http://www.intel.com/content/dam/www/public/us/en/documents/application-notes/virtualization-technology-flexmigration-application-note.pdf.
[...]
> If this bit is preserved on fork(), then no_new_privs must be checked
> (or it must be cleared on "unsafe" exec, but that's nasty).

I think you mean "preserved on execve()"?

WARNING: multiple messages have this Message-ID (diff)
From: Jann Horn <jann-XZ1E9jl8jIdeoWH0uzbU5w@public.gmane.org>
To: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
Cc: Kyle Huey <me-OhBmq/TcCDJWk0Htik3J/w@public.gmane.org>,
	Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
	John Stultz <john.stultz-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	"Michael S. Tsirkin"
	<mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Alexander Shishkin
	<alexander.shishkin-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
	Aravind Gopalakrishnan
	<Aravind.Gopalakrishnan-5C7GfCeVMHo@public.gmane.org>,
	Vlastimil Babka <vbabka-AlSwsSmVLrQ@public.gmane.org>,
	"Luis R. Rodriguez"
	<mcgrof-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Mateusz Guzik <mguzik-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Alex Thorlton <athorlton-sJ/iWh9BUns@public.gmane.org>,
	"Rafael J. Wysocki"
	<rafael.j.wysocki-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Dmitry Vyukov <dvyukov-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Vladimir Zapolskiy
	<vladimir_zapolskiy-nmGgyN9QBj3QT0dZR+AlfA@public.gmane.org>,
	Jiri Slaby <jslaby-AlSwsSmVLrQ@public.gmane.org>,
	Andrey Ryabinin
	<aryabinin-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>,
	Ben Segall <bsegall-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	mainta
Subject: Re: [PATCH] prctl,x86 Add PR_[GET|SET]_CPUID for controlling the CPUID instruction.
Date: Mon, 12 Sep 2016 19:56:56 +0200	[thread overview]
Message-ID: <20160912175656.GA8935@laptop.thejh.net> (raw)
In-Reply-To: <CALCETrVJAib918qn9CL4Tvyfok-8eAHimYDabXUF=1Nsxo4-Pw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Mon, Sep 12, 2016 at 09:56:11AM -0700, Andy Lutomirski wrote:
> On Sep 11, 2016 5:29 PM, "Kyle Huey" <me-OhBmq/TcCDJWk0Htik3J/w@public.gmane.org> wrote:
> >
> > rr (http://rr-project.org/), a userspace record-and-replay reverse-
> > execution debugger, would like to trap and emulate the CPUID instruction.
> > This would allow us to a) mask away certain hardware features that rr does
> > not support (e.g. RDRAND) and b) enable trace portability across machines
> > by providing constant results.
> >
> > Intel supports faulting on the CPUID instruction in newer processors. Bit
> > 31 of MSR_PLATFORM_INFO advertises support for this feature. It is
> > documented in detail in Section 2.3.2 of
> > http://www.intel.com/content/dam/www/public/us/en/documents/application-notes/virtualization-technology-flexmigration-application-note.pdf.
[...]
> If this bit is preserved on fork(), then no_new_privs must be checked
> (or it must be cleared on "unsafe" exec, but that's nasty).

I think you mean "preserved on execve()"?

  parent reply	other threads:[~2016-09-12 17:57 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-12  0:29 [PATCH] prctl,x86 Add PR_[GET|SET]_CPUID for controlling the CPUID instruction Kyle Huey
2016-09-12  0:29 ` Kyle Huey
2016-09-12  9:07 ` Borislav Petkov
2016-09-12  9:07   ` Borislav Petkov
2016-09-12 14:15   ` Kyle Huey
2016-09-12 14:15     ` Kyle Huey
2016-09-12 14:34     ` Borislav Petkov
2016-09-12 14:34       ` Borislav Petkov
2016-09-12 14:34       ` Borislav Petkov
2016-09-13 18:42     ` Kyle Huey
2016-09-13 18:42       ` Kyle Huey
2016-09-12 16:56 ` Andy Lutomirski
2016-09-12 16:56   ` Andy Lutomirski
2016-09-12 17:18   ` Borislav Petkov
2016-09-12 17:18     ` Borislav Petkov
2016-09-12 17:56   ` Jann Horn [this message]
2016-09-12 17:56     ` Jann Horn
2016-09-12 21:07     ` Andy Lutomirski
2016-09-12 21:07       ` Andy Lutomirski
2016-09-14  6:13   ` Kyle Huey
2016-09-14  6:13     ` Kyle Huey
2016-09-14 18:52     ` Andy Lutomirski
2016-09-14 18:52       ` Andy Lutomirski
2016-09-14 19:22       ` Andrew Cooper
2016-09-14 19:22         ` Andrew Cooper
2016-09-14 19:23       ` Boris Ostrovsky
2016-09-14 19:23         ` Boris Ostrovsky
2016-09-14 19:28         ` Andrew Cooper
2016-09-14 19:28           ` Andrew Cooper
2016-09-14 19:36           ` Andy Lutomirski
2016-09-14 19:36             ` Andy Lutomirski
2016-09-14 19:42             ` Andrew Cooper
2016-09-14 19:42               ` Andrew Cooper
2016-09-14 19:42             ` [PATCH] prctl, x86 " Andrew Cooper
2016-09-12 17:37 ` [PATCH] prctl,x86 " Andi Kleen
2016-09-12 18:25   ` Henrique de Moraes Holschuh

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