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 X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1874AC433E0 for ; Wed, 3 Jun 2020 08:48:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E504F20674 for ; Wed, 3 Jun 2020 08:48:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dSB/FFMv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726635AbgFCIsc (ORCPT ); Wed, 3 Jun 2020 04:48:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59706 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725888AbgFCIsb (ORCPT ); Wed, 3 Jun 2020 04:48:31 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A8B4C05BD43 for ; Wed, 3 Jun 2020 01:48:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=BFvkRQdilbHJpPYwzqAswTtjQYRfuGDRfAkqNIhsFDs=; b=dSB/FFMvXM6gSVR3G4GAbDiYbd MQL5YzfLb5qlxJ3vciS6/CwLB0hiRsHpcW5fkV2zHiRkJzME1wLQI6UfThi6ljDtXue3M6roQMNUV E3KCME2glmjDA2tSJ6jX4P9w6yE55UKrTrSgJM8LLKYEPbub8l4u1uBR1G3jRE3PEVx+BSkcykza2 S1UBqRwtIX1yr9SKvXFAdxxqOVHRFVb2RezL9qdTxFeBVhay25tI6vlYAXXsG3T3O0rHNvV8rwEgy Rrwu/jg5QpuSxE1gANX4JasiqiXbf+9kMlCMQBNqr8stbzy4pEEuxnRuTZkctOVtdl/9xQoR5/8Sw WncHfiWA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jgP4O-0005yL-7P; Wed, 03 Jun 2020 08:48:20 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5BA243035D4; Wed, 3 Jun 2020 10:48:18 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5128B205F7349; Wed, 3 Jun 2020 10:48:18 +0200 (CEST) Date: Wed, 3 Jun 2020 10:48:18 +0200 From: Peter Zijlstra To: Marco Elver Cc: Nick Desaulniers , Will Deacon , Borislav Petkov , Thomas Gleixner , Ingo Molnar , clang-built-linux , "Paul E. McKenney" , Dmitry Vyukov , Alexander Potapenko , Andrey Konovalov , kasan-dev , LKML Subject: [PATCH] rcu: Fixup noinstr warnings Message-ID: <20200603084818.GB2627@hirez.programming.kicks-ass.net> References: <20200602184409.22142-1-elver@google.com> <20200602191936.GE2604@hirez.programming.kicks-ass.net> <20200602193853.GF2604@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200602193853.GF2604@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 02, 2020 at 09:38:53PM +0200, Peter Zijlstra wrote: > That said; noinstr's __no_sanitize combined with atomic_t might be > 'interesting', because the regular atomic things have explicit > annotations in them. That should give validation warnings for the right > .config, I'll have to go try -- so far I've made sure to never enable > the *SAN stuff. --- Subject: rcu: Fixup noinstr warnings A KCSAN build revealed we have explicit annoations through atomic_t usage, switch to arch_atomic_*() for the respective functions. vmlinux.o: warning: objtool: rcu_nmi_exit()+0x4d: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: rcu_dynticks_eqs_enter()+0x25: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: rcu_nmi_enter()+0x4f: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: rcu_dynticks_eqs_exit()+0x2a: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: __rcu_is_watching()+0x25: call to __kcsan_check_access() leaves .noinstr.text section Signed-off-by: Peter Zijlstra (Intel) --- kernel/rcu/tree.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index c716eadc7617..162656b80db9 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -250,7 +250,7 @@ static noinstr void rcu_dynticks_eqs_enter(void) * next idle sojourn. */ rcu_dynticks_task_trace_enter(); // Before ->dynticks update! - seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks); + seq = arch_atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks); // RCU is no longer watching. Better be in extended quiescent state! WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & RCU_DYNTICK_CTRL_CTR)); @@ -274,13 +274,13 @@ static noinstr void rcu_dynticks_eqs_exit(void) * and we also must force ordering with the next RCU read-side * critical section. */ - seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks); + seq = arch_atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks); // RCU is now watching. Better not be in an extended quiescent state! rcu_dynticks_task_trace_exit(); // After ->dynticks update! WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & RCU_DYNTICK_CTRL_CTR)); if (seq & RCU_DYNTICK_CTRL_MASK) { - atomic_andnot(RCU_DYNTICK_CTRL_MASK, &rdp->dynticks); + arch_atomic_andnot(RCU_DYNTICK_CTRL_MASK, &rdp->dynticks); smp_mb__after_atomic(); /* _exit after clearing mask. */ } } @@ -313,7 +313,7 @@ static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) { struct rcu_data *rdp = this_cpu_ptr(&rcu_data); - return !(atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR); + return !(arch_atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR); } /* @@ -692,6 +692,7 @@ noinstr void rcu_nmi_exit(void) { struct rcu_data *rdp = this_cpu_ptr(&rcu_data); + instrumentation_begin(); /* * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks. * (We are exiting an NMI handler, so RCU better be paying attention @@ -705,7 +706,6 @@ noinstr void rcu_nmi_exit(void) * leave it in non-RCU-idle state. */ if (rdp->dynticks_nmi_nesting != 1) { - instrumentation_begin(); trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2, atomic_read(&rdp->dynticks)); WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */ @@ -714,7 +714,6 @@ noinstr void rcu_nmi_exit(void) return; } - instrumentation_begin(); /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_read(&rdp->dynticks)); WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */