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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 43E8DC43441 for ; Sun, 11 Nov 2018 20:06:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 102CA20869 for ; Sun, 11 Nov 2018 20:06:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 102CA20869 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731344AbeKLFzb (ORCPT ); Mon, 12 Nov 2018 00:55:31 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51894 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730984AbeKLFza (ORCPT ); Mon, 12 Nov 2018 00:55:30 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gLvt4-0000oM-4Z; Sun, 11 Nov 2018 19:59:14 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gLvsR-0001W1-7M; Sun, 11 Nov 2018 19:58:35 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Ingo Molnar" , "Steven Rostedt (VMware)" , "Mikulas Patocka" Date: Sun, 11 Nov 2018 19:49:05 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 114/366] branch-check: fix long->int truncation when profiling branches In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit 2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe upstream. The function __builtin_expect returns long type (see the gcc documentation), and so do macros likely and unlikely. Unfortunatelly, when CONFIG_PROFILE_ANNOTATED_BRANCHES is selected, the macros likely and unlikely expand to __branch_check__ and __branch_check__ truncates the long type to int. This unintended truncation may cause bugs in various kernel code (we found a bug in dm-writecache because of it), so it's better to fix __branch_check__ to return long. Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1805300818140.24812@file01.intranet.prod.int.rdu2.redhat.com Cc: Ingo Molnar Fixes: 1f0d69a9fc815 ("tracing: profile likely and unlikely annotations") Signed-off-by: Mikulas Patocka Signed-off-by: Steven Rostedt (VMware) [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- include/linux/compiler.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -105,7 +105,7 @@ void ftrace_likely_update(struct ftrace_ #define unlikely_notrace(x) __builtin_expect(!!(x), 0) #define __branch_check__(x, expect) ({ \ - int ______r; \ + long ______r; \ static struct ftrace_branch_data \ __attribute__((__aligned__(4))) \ __attribute__((section("_ftrace_annotated_branch"))) \