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=-0.8 required=3.0 tests=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 7D00DC433DF for ; Thu, 14 May 2020 18:44:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C95620657 for ; Thu, 14 May 2020 18:44:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727772AbgENSob (ORCPT ); Thu, 14 May 2020 14:44:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726667AbgENSob (ORCPT ); Thu, 14 May 2020 14:44:31 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 055B6C061A0C for ; Thu, 14 May 2020 11:44:31 -0700 (PDT) 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 1jZIq1-0005j2-Pr; Thu, 14 May 2020 20:44:09 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 019A81004CE; Thu, 14 May 2020 20:44:08 +0200 (CEST) From: Thomas Gleixner To: Andy Lutomirski Cc: LKML , X86 ML , "Paul E. McKenney" , Andy Lutomirski , Alexandre Chartre , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Mathieu Desnoyers , Josh Poimboeuf , Will Deacon Subject: Re: [patch V4 part 4 08/24] x86/entry: Provide IDTENTRY_IST In-Reply-To: References: <20200505134926.578885807@linutronix.de> <20200505135314.137125609@linutronix.de> Date: Thu, 14 May 2020 20:44:08 +0200 Message-ID: <87v9kyxsp3.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain 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 Andy Lutomirski writes: > On Tue, May 5, 2020 at 7:16 AM Thomas Gleixner wrote: >> >> Same as IDTENTRY but for exceptions which run on Interrupt STacks (IST) on >> 64bit. For 32bit this maps to IDTENTRY. >> >> There are 3 variants which will be used: >> IDTENTRY_MCE >> IDTENTRY_DB >> IDTENTRY_NMI >> >> These map to IDTENTRY_IST, but only the MCE and DB variants are emitting >> ASM code as the NMI entry needs hand crafted ASM still. >> >> The function defines do not contain any idtenter/exit calls as these >> exceptions need special treatment. > > Okay I guess, but in the long run I'm guessing that we'll want to > merge a bunch of this to DECLARE_IDTENTRY_NOASM and just manually emit > the special cases in entry_32/64.S. The ASM is still the paranoid muck which is emitted nicely. But on the C side this needs a different treatment than the regular exceptions which all use idtentry_enter() before and idtentry_exit() after the handler function body. Those need magic things before and after nmi_enter/exit(). That's why the C function is directly called and does not have any automatically emitted enter/exit stuff like the other IDTENTRY variants. Thanks, tglx