From: "Paul E. McKenney" <paulmck@linux.ibm.com>
To: Akira Yokosawa <akiyks@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>,
Andrea Parri <andrea.parri@amarulasolutions.com>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Alan Stern <stern@rowland.harvard.edu>,
Will Deacon <will.deacon@arm.com>,
Boqun Feng <boqun.feng@gmail.com>,
Nicholas Piggin <npiggin@gmail.com>,
David Howells <dhowells@redhat.com>,
Jade Alglave <j.alglave@ucl.ac.uk>,
Luc Maranget <luc.maranget@inria.fr>,
Daniel Lustig <dlustig@nvidia.com>
Subject: Re: [RFC PATCH] tools/memory-model: Remove (dep ; rfi) from ppo
Date: Tue, 26 Feb 2019 07:04:27 -0800 [thread overview]
Message-ID: <20190226150427.GM4072@linux.ibm.com> (raw)
In-Reply-To: <b8cdca74-6f7d-cfe3-636c-41a59b0d86da@gmail.com>
On Tue, Feb 26, 2019 at 11:56:57PM +0900, Akira Yokosawa wrote:
> Hi Paul,
>
> On Tue, 26 Feb 2019 06:28:45 -0800, Paul E. McKenney wrote:
> > On Tue, Feb 26, 2019 at 02:49:06PM +0100, Peter Zijlstra wrote:
> >> On Tue, Feb 26, 2019 at 12:38:13PM +0100, Borislav Petkov wrote:
> >>> On Tue, Feb 26, 2019 at 12:30:08PM +0100, Peter Zijlstra wrote:
> >>>> When I used the argc variant, gcc-8 'works', but with s/argc/1/ it is
> >>>> still broken.
> >>>
> >>> As requested on IRC:
> >>
> >> What I asked was if you could get your GCC developer friends to have a
> >> look at this :-)
> >
> > Yes, this all is a bit on the insane side from a kernel viewpoint.
> > But the paper you found does not impose this; it has instead been there
> > for about 20 years, back before C and C++ admitted to the existence
> > of concurrency.
>
> By "it", do you mean the concept of "pointer provenance"?
>
> I'm asking because the paper's header reads:
>
> "ISO/IEC JTC1/SC22/WG14 N2311, 2018-11-09"
>
> Just wanted to make sure.
This paper introduces neither pointer provenance nor indeterminate-on-free,
but rather proposes modification. These things have been around for a
few decades.
Thanx, Paul
> Thanks, Akira
>
> > But of course compilers are getting more aggressive,
> > and yes, some of the problems show up in single-threaded code.
> >
> > The usual response is "then cast the pointers to intptr_t!" but of
> > course that breaks type checking.
> >
> > There is an effort to claw back the concurrency pieces, and I would
> > be happy to run the resulting paper past you guys.
> >
> > I must confess to not being all that sympathetic to code that takes
> > advantage of happenstance stack-frame layout. Is there some reason
> > we need that?
> >
> > Thanx, Paul
> >
>
next prev parent reply other threads:[~2019-02-26 15:04 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-19 22:57 [RFC PATCH] tools/memory-model: Remove (dep ; rfi) from ppo Andrea Parri
2019-02-20 2:01 ` Paul E. McKenney
2019-02-20 9:26 ` Peter Zijlstra
2019-02-20 9:57 ` Will Deacon
2019-02-20 13:17 ` Andrea Parri
2019-02-20 13:14 ` Andrea Parri
2019-02-20 13:27 ` Peter Zijlstra
2019-02-22 11:21 ` Andrea Parri
2019-02-22 13:00 ` Peter Zijlstra
2019-02-25 17:55 ` Paul E. McKenney
2019-02-26 9:21 ` Peter Zijlstra
2019-02-26 9:30 ` Peter Zijlstra
2019-02-26 10:45 ` Peter Zijlstra
2019-02-26 11:21 ` Peter Zijlstra
2019-02-26 11:25 ` Peter Zijlstra
2019-02-26 11:30 ` Peter Zijlstra
2019-02-26 11:38 ` Borislav Petkov
2019-02-26 13:49 ` Peter Zijlstra
2019-02-26 14:28 ` Paul E. McKenney
2019-02-26 14:47 ` Peter Zijlstra
2019-02-26 15:39 ` Paul E. McKenney
2019-02-26 14:56 ` Akira Yokosawa
2019-02-26 15:04 ` Paul E. McKenney [this message]
2019-02-26 15:09 ` Akira Yokosawa
2019-02-26 15:04 ` Peter Zijlstra
2019-03-06 15:46 ` Akira Yokosawa
2019-03-06 16:58 ` Peter Zijlstra
2019-03-06 17:26 ` Paul E. McKenney
2019-03-06 17:24 ` Paul E. McKenney
2019-03-02 15:27 ` Akira Yokosawa
2019-03-04 16:09 ` Paul E. McKenney
2019-02-20 13:41 ` Will Deacon
2019-02-20 15:30 ` Alan Stern
2019-02-20 15:30 ` Alan Stern
2019-02-20 15:22 ` Alan Stern
2019-02-20 15:22 ` Alan Stern
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