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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 A5AA8C433DF for ; Fri, 22 May 2020 16:09:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88E60207BC for ; Fri, 22 May 2020 16:09:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730678AbgEVQI7 (ORCPT ); Fri, 22 May 2020 12:08:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730562AbgEVQIy (ORCPT ); Fri, 22 May 2020 12:08:54 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12D39C05BD43; Fri, 22 May 2020 09:08:54 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jcAE5-0000Bg-OP; Fri, 22 May 2020 18:08:49 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 69E6A1C0095; Fri, 22 May 2020 18:08:49 +0200 (CEST) Date: Fri, 22 May 2020 16:08:49 -0000 From: "tip-bot2 for Marco Elver" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/kcsan] kcsan: Avoid inserting __tsan_func_entry/exit if possible Cc: Marco Elver , Borislav Petkov , Will Deacon , "Peter Zijlstra (Intel)" , x86 , LKML In-Reply-To: <20200521142047.169334-3-elver@google.com> References: <20200521142047.169334-3-elver@google.com> MIME-Version: 1.0 Message-ID: <159016372927.17951.13208558813193779021.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the locking/kcsan branch of tip: Commit-ID: 3bc9e5b0725b353b921feaf2c10bb4a9f932646f Gitweb: https://git.kernel.org/tip/3bc9e5b0725b353b921feaf2c10bb4a9f932646f Author: Marco Elver AuthorDate: Thu, 21 May 2020 16:20:38 +02:00 Committer: Borislav Petkov CommitterDate: Fri, 22 May 2020 14:36:19 +02:00 kcsan: Avoid inserting __tsan_func_entry/exit if possible To avoid inserting __tsan_func_{entry,exit}, add option if supported by compiler. Currently only Clang can be told to not emit calls to these functions. It is safe to not emit these, since KCSAN does not rely on them. Note that, if we disable __tsan_func_{entry,exit}(), we need to disable tail-call optimization in sanitized compilation units, as otherwise we may skip frames in the stack trace; in particular when the tail called function is one of the KCSAN's runtime functions, and a report is generated, we might miss the function where the actual access occurred. Since __tsan_func_{entry,exit}() insertion effectively disabled tail-call optimization, there should be no observable change. This was caught and confirmed with kcsan-test & UNWINDER_ORC. Signed-off-by: Marco Elver Signed-off-by: Borislav Petkov Acked-by: Will Deacon Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200521142047.169334-3-elver@google.com --- scripts/Makefile.kcsan | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan index caf1111..20337a7 100644 --- a/scripts/Makefile.kcsan +++ b/scripts/Makefile.kcsan @@ -1,6 +1,15 @@ # SPDX-License-Identifier: GPL-2.0 ifdef CONFIG_KCSAN -CFLAGS_KCSAN := -fsanitize=thread +# GCC and Clang accept backend options differently. Do not wrap in cc-option, +# because Clang accepts "--param" even if it is unused. +ifdef CONFIG_CC_IS_CLANG +cc-param = -mllvm -$(1) +else +cc-param = --param -$(1) +endif + +CFLAGS_KCSAN := -fsanitize=thread \ + $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) endif # CONFIG_KCSAN