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 D2476C761AF for ; Tue, 28 Mar 2023 15:12:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230318AbjC1PML (ORCPT ); Tue, 28 Mar 2023 11:12:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52684 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230191AbjC1PMK (ORCPT ); Tue, 28 Mar 2023 11:12:10 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89C7586AB for ; Tue, 28 Mar 2023 08:11:31 -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 ams.source.kernel.org (Postfix) with ESMTPS id BE793B81D9E for ; Tue, 28 Mar 2023 15:09:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24B9AC433D2; Tue, 28 Mar 2023 15:09:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680016194; bh=bi/be8Q5qAxoSaDo4VTQmTpZr1Y/FUdfULkl/EQS38M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=n9essiE8Qk9StB45Q3Ax5E0xBCNabcVZ4Hb1c0dfjAeeDOouRq3KwYQCkJo8zW+9Y Z83GPx9Lck+cpsJm/QbvISMxrJoaU+kR0sm92dzkUr7L0NXPtBdqIvqsAiK2IbINSD /36CR+mzvvrWzlSEhayC78mQUD7y4E61ZRy2huSY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mark Rutland , Thomas Gleixner , "Paul E. McKenney" , Sasha Levin Subject: [PATCH 5.15 069/146] entry: Snapshot thread flags Date: Tue, 28 Mar 2023 16:42:38 +0200 Message-Id: <20230328142605.595981420@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230328142602.660084725@linuxfoundation.org> References: <20230328142602.660084725@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mark Rutland [ Upstream commit 6ce895128b3bff738fe8d9dd74747a03e319e466 ] Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race. To avoid such issues, a snapshot of the flags has to be taken prior to using them. Some places already use READ_ONCE() for that, others do not. Convert them all to the new flag accessor helpers. Signed-off-by: Mark Rutland Signed-off-by: Thomas Gleixner Acked-by: Paul E. McKenney Link: https://lore.kernel.org/r/20211129130653.2037928-3-mark.rutland@arm.com Stable-dep-of: b41651405481 ("entry/rcu: Check TIF_RESCHED _after_ delayed RCU wake-up") Signed-off-by: Sasha Levin --- include/linux/entry-kvm.h | 2 +- kernel/entry/common.c | 4 ++-- kernel/entry/kvm.c | 4 ++-- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/include/linux/entry-kvm.h b/include/linux/entry-kvm.h index 0d7865a0731ce..07c878d6e323e 100644 --- a/include/linux/entry-kvm.h +++ b/include/linux/entry-kvm.h @@ -75,7 +75,7 @@ static inline void xfer_to_guest_mode_prepare(void) */ static inline bool __xfer_to_guest_mode_work_pending(void) { - unsigned long ti_work = READ_ONCE(current_thread_info()->flags); + unsigned long ti_work = read_thread_flags(); return !!(ti_work & XFER_TO_GUEST_MODE_WORK); } diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 998bdb7b8bf7f..3ce3a0a6c762e 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -187,7 +187,7 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, /* Check if any of the above work has queued a deferred wakeup */ tick_nohz_user_enter_prepare(); - ti_work = READ_ONCE(current_thread_info()->flags); + ti_work = read_thread_flags(); } /* Return the latest work state for arch_exit_to_user_mode() */ @@ -196,7 +196,7 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, static void exit_to_user_mode_prepare(struct pt_regs *regs) { - unsigned long ti_work = READ_ONCE(current_thread_info()->flags); + unsigned long ti_work = read_thread_flags(); lockdep_assert_irqs_disabled(); diff --git a/kernel/entry/kvm.c b/kernel/entry/kvm.c index 49972ee99aff6..96d476e06c777 100644 --- a/kernel/entry/kvm.c +++ b/kernel/entry/kvm.c @@ -26,7 +26,7 @@ static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work) if (ret) return ret; - ti_work = READ_ONCE(current_thread_info()->flags); + ti_work = read_thread_flags(); } while (ti_work & XFER_TO_GUEST_MODE_WORK || need_resched()); return 0; } @@ -43,7 +43,7 @@ int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu) * disabled in the inner loop before going into guest mode. No need * to disable interrupts here. */ - ti_work = READ_ONCE(current_thread_info()->flags); + ti_work = read_thread_flags(); if (!(ti_work & XFER_TO_GUEST_MODE_WORK)) return 0; -- 2.39.2