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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 A22F6C433E2 for ; Wed, 22 Jul 2020 18:25:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7423F207E8 for ; Wed, 22 Jul 2020 18:25:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="wTi597w8"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="rzdia+Of" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732019AbgGVSZ6 (ORCPT ); Wed, 22 Jul 2020 14:25:58 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:51176 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726462AbgGVSZ6 (ORCPT ); Wed, 22 Jul 2020 14:25:58 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1595442356; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=De2Oo3WYSjxDYyxtzHkgNAFZFz1uqYilAgoG2Mi1/0E=; b=wTi597w8/WAvYo6fRhtK8Csx9AtQpbzEmpgE3ZBRJ9pE/j2ad+0y5sTi0vRAghKFrxVejv EpcFdThV2BtJrR/Gf/tlO7DUSE4/2+wnqa6iCfEIyHY0yDh9QnXo5ZBOj64gGsX6qKsPkd 8ZzWGZ5VrSiVViESnb4dXPf0P6vk+RTYWNZum31cPDhAQsSlZgNQW4wDP82kQf/bUZutwN so3gzqknEwCf/CFXSRbqx9VmYjIi49DyJpDeLcQdHTL3H4Zh9V/Vuco21Cem5ntUFIDcH4 DFuwT5YrOXYcUyvpd17rnlvGAaFdbIE9Q4FvGjV8h/4LrIVkhQ64CyufKz2ZOg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1595442356; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=De2Oo3WYSjxDYyxtzHkgNAFZFz1uqYilAgoG2Mi1/0E=; b=rzdia+Of0BW+JLmcJkwDHHcZakCXbL4PaRIYIuDNTEyyNIpL5hKfZCt7BOCx58Zq7T0/9t yJk/QNK9n7b1XmCA== To: Kees Cook Cc: LKML , x86@kernel.org, linux-arch@vger.kernel.org, Will Deacon , Arnd Bergmann , Mark Rutland , Keno Fischer , Paolo Bonzini , kvm@vger.kernel.org, Gabriel Krisman Bertazi Subject: Re: [patch V4 10/15] x86/entry: Use generic syscall entry function In-Reply-To: <202007211440.BEF76E2@keescook> References: <20200721105706.030914876@linutronix.de> <20200721110809.325060396@linutronix.de> <202007211440.BEF76E2@keescook> Date: Wed, 22 Jul 2020 20:25:55 +0200 Message-ID: <87wo2vz9sc.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kees, Kees Cook writes: > On Tue, Jul 21, 2020 at 12:57:16PM +0200, Thomas Gleixner wrote: > > This doesn't look very expensive, and they certain indicate really bad > conditions. Does this need to be behind a CONFIG? (Whatever the answer, > we can probably make those changes in a later series -- some of these > also look not arch-specific...) The most expensive part is native_save_flags(). The extra branches could be visible in benchmarks, but its a good question whether this should be just enabled. I just keep it as is for now as I would need to make the flags and the on_thread_stack() part x86 specific anyway, but yes we can revisit that once we agreed on the general direction of this. Thanks, tglx