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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 00CD0C35647 for ; Fri, 21 Feb 2020 13:50:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CADC4208C4 for ; Fri, 21 Feb 2020 13:50:43 +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="O/PpAFrM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728891AbgBUNum (ORCPT ); Fri, 21 Feb 2020 08:50:42 -0500 Received: from merlin.infradead.org ([205.233.59.134]:45540 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728841AbgBUNuk (ORCPT ); Fri, 21 Feb 2020 08:50:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=SKWUMBjFXunYZktv3+PwsTSKyH9hFj1H3mSFlJw71rk=; b=O/PpAFrMCSLa6/ZWKy82GufWPu yg2jaXTm6OaoPCGOw8Pv9uwwWGnn0YapFAWHIPisIplZZaKEPIVe3XuIekUKy9thKTI4mSFt80xfT LdsxNORHiMMOZDNP7l+fGoziLk5kRJZBxXJR/LPLpQiw5u5ok4BF8htn7gKQSJON/2sMV/H7coN6K 6uRP+0V82wdNmmyQL8NFrEXmlbFARdfU6G7KT/QMpanZns1UUpwVkHLChXdoxAJlyoCR+fTo+zvW+ avDX4fijN0KzQvq7qw/Wtp5EIa3afNRb51Twger/reBbBvkhGv8pxZyGTQ4pre9BuM8uBX8WFmw+x SNWSEHaA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j58gw-0006VH-IG; Fri, 21 Feb 2020 13:50:06 +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 8906930783F; Fri, 21 Feb 2020 14:48:08 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 3B01829D740B7; Fri, 21 Feb 2020 14:50:01 +0100 (CET) Message-Id: <20200221134216.690116768@infradead.org> User-Agent: quilt/0.65 Date: Fri, 21 Feb 2020 14:34:40 +0100 From: Peter Zijlstra To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, rostedt@goodmis.org Cc: peterz@infradead.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 Subject: [PATCH v4 24/27] x86/int3: Avoid atomic instrumentation References: <20200221133416.777099322@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use arch_atomic_*() and READ_ONCE_NOCHECK() to ensure nothing untoward creeps in and ruins things. That is; this is the INT3 text poke handler, strictly limit the code that runs in it, lest we inadvertenly hit yet another INT3. Reported-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/kernel/alternative.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -960,9 +960,9 @@ static struct bp_patching_desc *bp_desc; static __always_inline struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp) { - struct bp_patching_desc *desc = READ_ONCE(*descp); /* rcu_dereference */ + struct bp_patching_desc *desc = READ_ONCE_NOCHECK(*descp); /* rcu_dereference */ - if (!desc || !atomic_inc_not_zero(&desc->refs)) + if (!desc || !arch_atomic_inc_not_zero(&desc->refs)) return NULL; return desc; @@ -971,7 +971,7 @@ struct bp_patching_desc *try_get_desc(st static __always_inline void put_desc(struct bp_patching_desc *desc) { smp_mb__before_atomic(); - atomic_dec(&desc->refs); + arch_atomic_dec(&desc->refs); } static __always_inline void *text_poke_addr(struct text_poke_loc *tp)