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 3A8E4C433EF for ; Thu, 16 Jun 2022 01:26:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353312AbiFPB0d (ORCPT ); Wed, 15 Jun 2022 21:26:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344002AbiFPB0b (ORCPT ); Wed, 15 Jun 2022 21:26:31 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E9BE51E54; Wed, 15 Jun 2022 18:26:31 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A604561CB3; Thu, 16 Jun 2022 01:26:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01816C3411A; Thu, 16 Jun 2022 01:26:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1655342790; bh=RVnT4ZhKcCC/rRu0iJrXXNZrI1VuclV9+DrhvH6u4bU=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=m8F26jI1i6uGOOKDtqA1FxbbM8hOQdLFCLpDMfzpCHfDhoDYCzdyzkP+oOBE3ora0 1XtpZPTit4/HwPfcHp7jAPQ+pf8n+x+IWjkcKxSd0iU9uKqcFAGb6oMj8rH5QtgxAI 9YXBV6O7okl7g7dcoNq0SNnlo/fQ0F5fMplHg9vBUJO3nG7FFRMccmSI+EL5rLmUaf Tjv70dYHf08MgWiz5AX3OK4/9RIGVFtQhO/GVQ4KzYNWnSPMeCT85coIVFvYrfW8Xh 6TA6MPtt+LP5VHoRRJQm3XWxDAsqMg8eaqDt9/xNn7fngOJXN8MTXwJJywBWeOVXR/ kW+/qtOoHFKAw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 932E05C0587; Wed, 15 Jun 2022 18:26:29 -0700 (PDT) Date: Wed, 15 Jun 2022 18:26:29 -0700 From: "Paul E. McKenney" To: Stephen Rothwell Cc: Nathan Chancellor , Frederic Weisbecker , Sami Tolvanen , Kees Cook , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-next@vger.kernel.org Subject: Re: Contextual conflict between kspp and rcu trees Message-ID: <20220616012629.GL1790663@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20220616091634.55ebbdb0@canb.auug.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220616091634.55ebbdb0@canb.auug.org.au> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 16, 2022 at 09:16:34AM +1000, Stephen Rothwell wrote: > Hi Nathan, > > On Wed, 15 Jun 2022 12:55:53 -0700 Nathan Chancellor wrote: > > > > There is a contextual conflict between commit e1d337335207 ("cfi: Fix > > __cfi_slowpath_diag RCU usage with cpuidle") in the kspp tree and commit > > dcc0c11aa87b ("rcu/context-tracking: Remove rcu_irq_enter/exit()") in > > the rcu tree, which is visible when building ARCH=arm64 defconfig + > > CONFIG_LTO_CLANG_THIN=y + CONFIG_CFI_CLANG=y with clang: > > > > kernel/cfi.c:298:3: error: call to undeclared function 'rcu_irq_enter'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] > > rcu_irq_enter(); > > ^ > > kernel/cfi.c:298:3: note: did you mean 'ct_irq_enter'? > > ./include/linux/context_tracking_irq.h:6:6: note: 'ct_irq_enter' declared here > > void ct_irq_enter(void); > > ^ > > kernel/cfi.c:307:3: error: call to undeclared function 'rcu_irq_exit'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] > > rcu_irq_exit(); > > ^ > > kernel/cfi.c:307:3: note: did you mean 'ct_irq_exit'? > > ./include/linux/context_tracking_irq.h:7:6: note: 'ct_irq_exit' declared here > > void ct_irq_exit(void); > > ^ > > 2 errors generated. > > > > > > Per the above RCU commit and commit 6c5218715286 ("context_tracking: > > Take IRQ eqs entrypoints over RCU"), it appears that the following diff > > is the proper fix up. Would you mind applying it to the merge of > > whichever tree comes second if possible? I did build and boot test it > > but it would not be a bad idea for Sami and Frederic to verify that it > > is correct so that Kees/Paul can mention it to Linus :) > > > > Cheers, > > Nathan > > > > diff --git a/kernel/cfi.c b/kernel/cfi.c > > index 08102d19ec15..2046276ee234 100644 > > --- a/kernel/cfi.c > > +++ b/kernel/cfi.c > > @@ -295,7 +295,7 @@ static inline cfi_check_fn find_check_fn(unsigned long ptr) > > rcu_idle = !rcu_is_watching(); > > if (rcu_idle) { > > local_irq_save(flags); > > - rcu_irq_enter(); > > + ct_irq_enter(); > > } > > > > if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) > > @@ -304,7 +304,7 @@ static inline cfi_check_fn find_check_fn(unsigned long ptr) > > fn = find_module_check_fn(ptr); > > > > if (rcu_idle) { > > - rcu_irq_exit(); > > + ct_irq_exit(); > > local_irq_restore(flags); > > } > > > > I will apply that to the merge of the rcu tree today (unless Paul finds > time to update (and test :-) ) the rcu tree before I get to it) as the > CFI fix is now in Linus' tree. Please! In theory, I could rebase -rcu to linus/master now, but in practice the odds of it producing something useful are all too low. I will take care of it tomorrow (Thursday) morning, Pacific Time. Thanx, Paul