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=-3.8 required=3.0 tests=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 7B67EC4BA09 for ; Tue, 25 Feb 2020 23:29:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5295B24680 for ; Tue, 25 Feb 2020 23:29:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729827AbgBYX3s (ORCPT ); Tue, 25 Feb 2020 18:29:48 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:55647 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729849AbgBYX0F (ORCPT ); Tue, 25 Feb 2020 18:26:05 -0500 Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1j6jaG-0004dD-Qy; Wed, 26 Feb 2020 00:25:49 +0100 Received: from nanos.tec.linutronix.de (localhost [IPv6:::1]) by nanos.tec.linutronix.de (Postfix) with ESMTP id D7A7C10408C; Wed, 26 Feb 2020 00:25:36 +0100 (CET) Message-Id: <20200225222648.395059616@linutronix.de> User-Agent: quilt/0.65 Date: Tue, 25 Feb 2020 23:16:08 +0100 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Steven Rostedt , Brian Gerst , Juergen Gross , Paolo Bonzini , Arnd Bergmann Subject: [patch 02/24] x86/entry/64: Avoid pointless code when CONTEXT_TRACKING=n References: <20200225221606.511535280@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 GAS cannot optimize out the test and conditional jump when context tracking is disabled and CALL_enter_from_user_mode is an empty macro. Wrap it in #ifdeffery. Will go away once all this is moved to C. Signed-off-by: Thomas Gleixner --- arch/x86/entry/entry_64.S | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -884,12 +884,14 @@ apicinterrupt IRQ_WORK_VECTOR irq_work TRACE_IRQS_OFF .endif +#ifdef CONFIG_CONTEXT_TRACKING .if \paranoid == 0 testb $3, CS(%rsp) jz .Lfrom_kernel_no_context_tracking_\@ CALL_enter_from_user_mode .Lfrom_kernel_no_context_tracking_\@: .endif +#endif movq %rsp, %rdi /* pt_regs pointer */