From: Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>
To: paulmck@kernel.org
Cc: Alan Stern <stern@rowland.harvard.edu>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>,
John Stultz <jstultz@google.com>,
Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>,
Frederic Weisbecker <frederic@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>,
Uladzislau Rezki <urezki@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang1211@gmail.com>,
Ingo Molnar <mingo@redhat.com>, Waiman Long <longman@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vlastimil Babka <vbabka@suse.cz>,
maged.michael@gmail.com, Mateusz Guzik <mjguzik@gmail.com>,
Gary Guo <gary@garyguo.net>,
rcu@vger.kernel.org, linux-mm@kvack.org, lkmm@lists.linux.dev
Subject: Re: [PATCH 1/2] compiler.h: Introduce ptr_eq() to preserve address dependency
Date: Mon, 30 Sep 2024 14:06:12 +0200 [thread overview]
Message-ID: <50bd6ecb-c8e3-4043-9040-b2b4ee71fc02@huaweicloud.com> (raw)
In-Reply-To: <973ae617-96a8-456a-a805-af3d61270125@paulmck-laptop>
Am 9/30/2024 um 1:04 PM schrieb Paul E. McKenney:
> On Mon, Sep 30, 2024 at 11:42:11AM +0200, Jonas Oberhauser wrote:
>>
>>
>> I also currently don't see any major difference between the constant and
>> register case. The point is that the address is known before loading into b,
>> and hence the compiler + hardware can speculatively load *b before loading
>> into b.
>
> In theory, true. In practice, in the register case, you need a little
> more bad luck for the compiler to be able to exploit your mistake.
If there's one thing I've never run out of, then it is bad luck with
technology.
jonas
next prev parent reply other threads:[~2024-09-30 12:06 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-28 13:51 [PATCH 0/2] Introduce ptr_eq() to preserve address dependency Mathieu Desnoyers
2024-09-28 13:51 ` [PATCH 1/2] compiler.h: " Mathieu Desnoyers
2024-09-28 14:49 ` Alan Stern
2024-09-28 15:30 ` Mathieu Desnoyers
2024-09-28 15:32 ` Mathieu Desnoyers
2024-09-28 15:49 ` Alan Stern
2024-09-28 15:55 ` Mathieu Desnoyers
2024-09-28 21:15 ` Alan Stern
2024-09-30 9:42 ` Jonas Oberhauser
2024-09-30 11:04 ` Paul E. McKenney
2024-09-30 12:06 ` Jonas Oberhauser [this message]
2024-09-30 13:54 ` Paul E. McKenney
2024-09-28 22:26 ` Alan Huang
2024-09-28 23:55 ` Boqun Feng
2024-09-29 0:20 ` Alan Huang
2024-09-30 8:57 ` Jonas Oberhauser
2024-09-30 9:15 ` Alan Huang
2024-09-30 9:27 ` Alan Huang
2024-09-30 9:33 ` Jonas Oberhauser
2024-09-30 10:12 ` Alan Huang
2024-09-30 11:26 ` Jonas Oberhauser
2024-09-30 16:43 ` Alan Stern
2024-09-30 17:05 ` Jonas Oberhauser
2024-09-30 18:53 ` Alan Stern
2024-10-01 17:11 ` David Laight
2024-10-01 22:57 ` 'Alan Stern'
2024-10-02 8:13 ` David Laight
2024-10-02 14:14 ` 'Alan Stern'
2024-10-02 15:24 ` David Laight
2024-10-03 1:50 ` 'Alan Stern'
2024-10-03 13:23 ` Mathieu Desnoyers
2024-10-03 17:07 ` David Laight
2024-10-03 18:00 ` Mathieu Desnoyers
2024-10-07 11:54 ` Jonas Oberhauser
2024-10-07 13:18 ` David Laight
2024-10-07 13:21 ` Mathieu Desnoyers
2024-10-07 14:59 ` Jonas Oberhauser
2024-09-28 23:24 ` Gary Guo
2024-09-29 10:36 ` Mathieu Desnoyers
2024-09-28 13:51 ` [PATCH 2/2] Documentation: RCU: Refer to ptr_eq() Mathieu Desnoyers
2024-09-28 14:58 ` Alan Stern
2024-09-28 15:09 ` Mathieu Desnoyers
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