From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09D69C04FDE for ; Mon, 12 Dec 2022 10:44:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232227AbiLLKoR (ORCPT ); Mon, 12 Dec 2022 05:44:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232098AbiLLKlR (ORCPT ); Mon, 12 Dec 2022 05:41:17 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6F4A9F037 for ; Mon, 12 Dec 2022 02:36:28 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 952741FB; Mon, 12 Dec 2022 02:37:08 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.40.60]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AC2723F5A1; Mon, 12 Dec 2022 02:36:26 -0800 (PST) Date: Mon, 12 Dec 2022 10:36:23 +0000 From: Mark Rutland To: Steven Rostedt Cc: Ard Biesheuvel , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, will@kernel.org, samitolvanen@google.com, keescook@chromium.org, mhiramat@kernel.org Subject: Re: [PATCH] ftrace: Allow WITH_ARGS flavour of graph tracer with shadow call stack Message-ID: References: <20221209143402.3332369-1-ardb@kernel.org> <20221209165139.37d033ee@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221209165139.37d033ee@gandalf.local.home> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 09, 2022 at 04:51:39PM -0500, Steven Rostedt wrote: > On Fri, 9 Dec 2022 14:40:25 +0000 > Mark Rutland wrote: > > > On Fri, Dec 09, 2022 at 03:34:02PM +0100, Ard Biesheuvel wrote: > > > The recent switch on arm64 from DYNAMIC_FTRACE_WITH_REGS to > > > DYNAMIC_FTRACE_WITH_ARGS failed to take into account that we currently > > > require the former in order to allow the function graph tracer to be > > > enabled in combination with shadow call stacks. This means that this is > > > no longer permitted at all, in spite of the fact that either flavour of > > > ftrace works perfectly fine in this combination. > > > > > > Given that arm64 is the only arch that implements shadow call stacks in > > > the first place, let's update the condition to just reflect the arm64 > > > change. When other architectures adopt shadow call stack support, this > > > can be revisited if needed. > > > > > > Signed-off-by: Ard Biesheuvel > > > > My bad; sorry about this, and thanks for the fix! > > > > Acked-by: Mark Rutland > > > > We should probably also add: > > > > Fixes: 26299b3f6ba26bfc ("ftrace: arm64: move from REGS to ARGS") > > Actually, I believe it is: > > Fixes: ddc9863e9e90 ("scs: Disable when function graph tracing is enabled") Ah; it's slightly more subtle since these were on different branches that got merged. Either's correct in its own branch, and the merge is where things went wrong. I think the overall least confusing thing is to bite the bullet and list both REGS and ARGS, i.e. depends on DYNAMIC_FTRACE_WITH_ARGS || DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER ... and for the fixes tag have: Fixes: ddc9863e9e90 ("scs: Disable when function graph tracing is enabled") That way the commit is correct regardless of the REGS -> ARGS conversion, and will work if backported independently. Thanks, Mark.