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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 38727C2BA83 for ; Fri, 14 Feb 2020 15:26:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0E7BF22314 for ; Fri, 14 Feb 2020 15:26:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581693990; bh=SgTjIAaM95kqOXyHnwAO1PZvRTAkVYcps3rUAVhvSpk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lwhkTDmHMdL7CLxAgdDWKrYrrg/BrPrpvxpEJWFVI08JximYYJwDOqbQJLBtQ+vJy r61INgXB4YJ5h/Y3Gf9IUyZ7iJIBrB9VFLr7o4u9HHL/NfFjvUDf6/dC/XhzzJ99Q2 qWSwOYmajQ9bdxPDgw2usNyDC+kWalx/Rw6EQCIk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387445AbgBNP03 (ORCPT ); Fri, 14 Feb 2020 10:26:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:38128 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729412AbgBNP02 (ORCPT ); Fri, 14 Feb 2020 10:26:28 -0500 Received: from lenoir.home (lfbn-ncy-1-985-231.w90-101.abo.wanadoo.fr [90.101.63.231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9862424649; Fri, 14 Feb 2020 15:26:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581693987; bh=SgTjIAaM95kqOXyHnwAO1PZvRTAkVYcps3rUAVhvSpk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vCaZTu7t+6nbZXtdlBvEI+Mmk2X6Wzh+0HOePLY2omun/hUDKwkNEg3WOzQqUbDF3 euM1mnfagGzxyj5OORC6d+HMh1a1Rt12fU7db+T4eFNGBvM+Dg9Z+26I/ujWAkRent lC57Mda11FDzvfU9IJKxA5TeDOSMe4Pp5Z+SFcV4= From: Frederic Weisbecker To: LKML Cc: Thomas Gleixner , Paul Burton , Peter Zijlstra , "David S . Miller" , Borislav Petkov , Benjamin Herrenschmidt , Paul Mackerras , Andy Lutomirski , Frederic Weisbecker , Ralf Baechle , Ingo Molnar , Will Deacon , Catalin Marinas , Michael Ellerman , Russell King Subject: [PATCH 1/5] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY Date: Fri, 14 Feb 2020 16:26:11 +0100 Message-Id: <20200214152615.25447-2-frederic@kernel.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200214152615.25447-1-frederic@kernel.org> References: <20200214152615.25447-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner Evaluating _TIF_NOHZ to decide whether to use the slow syscall entry path is not only pointless, it's actually counterproductive: 1) Context tracking code is invoked unconditionally before that flag is evaluated. 2) If the flag is set the slow path is invoked for nothing due to #1 Remove it. Signed-off-by: Thomas Gleixner Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Borislav Petkov Cc: Andy Lutomirski Signed-off-by: Frederic Weisbecker --- arch/x86/include/asm/thread_info.h | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index cf4327986e98..6cb9d1b0d1e6 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -133,14 +133,10 @@ struct thread_info { #define _TIF_X32 (1 << TIF_X32) #define _TIF_FSCHECK (1 << TIF_FSCHECK) -/* - * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for - * enter_from_user_mode() - */ +/* Work to do before invoking the actual syscall. */ #define _TIF_WORK_SYSCALL_ENTRY \ (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \ - _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \ - _TIF_NOHZ) + _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT) /* flags to check in __switch_to() */ #define _TIF_WORK_CTXSW_BASE \ -- 2.25.0