From: Andy Lutomirski <luto@amacapital.net>
To: Jann Horn <jann@thejh.net>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
John Stultz <john.stultz@linaro.org>,
Michal Hocko <mhocko@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Linux API <linux-api@vger.kernel.org>,
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>,
Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>,
Dmitry Vyukov <dvyukov@google.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>,
Kyle Huey <me@kylehuey.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Paul Gortmaker <paul.gortmaker@windriver.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>,
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 14:07:43 -0700 [thread overview]
Message-ID: <CALCETrXg4qo+oeq7xqMv9n9RehQ3jGjifJRK90jD=n-2r6=qaA@mail.gmail.com> (raw)
In-Reply-To: <20160912175656.GA8935@laptop.thejh.net>
On Sep 12, 2016 10:57 AM, "Jann Horn" <jann@thejh.net> wrote:
>
> 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()"?
Indeed.
So it should have defined and tested behavior on fork() and execve().
Maybe fork() should preserve the flag after all.
--Andy
next prev parent reply other threads:[~2016-09-12 21:08 UTC|newest]
Thread overview: 18+ 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 9:07 ` Borislav Petkov
2016-09-12 14:15 ` Kyle Huey
2016-09-12 14:34 ` Borislav Petkov
2016-09-13 18:42 ` Kyle Huey
2016-09-12 16:56 ` Andy Lutomirski
2016-09-12 17:18 ` Borislav Petkov
2016-09-12 17:56 ` Jann Horn
2016-09-12 21:07 ` Andy Lutomirski [this message]
2016-09-14 6:13 ` Kyle Huey
2016-09-14 18:52 ` Andy Lutomirski
2016-09-14 19:22 ` Andrew Cooper
2016-09-14 19:23 ` Boris Ostrovsky
2016-09-14 19:28 ` Andrew Cooper
2016-09-14 19:36 ` Andy Lutomirski
2016-09-14 19:42 ` Andrew Cooper
2016-09-12 17:37 ` Andi Kleen
2016-09-12 18:25 ` Henrique de Moraes Holschuh
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