From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: [PATCH v3 04/22] x86/doublefault: Make memmove() notrace/NOKPROBE Date: Wed, 19 Feb 2020 10:55:13 -0500 Message-ID: <20200219105513.4b0b7f29@gandalf.local.home> References: <20200219144724.800607165@infradead.org> <20200219150744.604459293@infradead.org> <20200219103614.2299ff61@gandalf.local.home> <20200219154031.GE18400@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mail.kernel.org ([198.145.29.99]:47408 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726604AbgBSPzR (ORCPT ); Wed, 19 Feb 2020 10:55:17 -0500 In-Reply-To: <20200219154031.GE18400@hirez.programming.kicks-ass.net> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, luto@kernel.org, tony.luck@intel.com, frederic@kernel.org, dan.carpenter@oracle.com, mhiramat@kernel.org On Wed, 19 Feb 2020 16:40:31 +0100 Peter Zijlstra wrote: > > Hmm, for things like this, which is adding notrace because of a single > > instance of it (although it is fine to trace in any other instance), it > > would be nice to have a gcc helper that could call "memmove+5" which > > would skip the tracing portion. > > Or just open-code the memmove() in do_double_fault() I suppose. I don't > think we care about super optimized code there. It's the bloody ESPFIX > trainwreck. Or just create a memmove_notrace() version and use that. -- Steve