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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 0A0F5C433DF for ; Thu, 14 May 2020 12:33:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFE86206DA for ; Thu, 14 May 2020 12:33:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726156AbgENMd2 (ORCPT ); Thu, 14 May 2020 08:33:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1725925AbgENMd1 (ORCPT ); Thu, 14 May 2020 08:33:27 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8283C061A0C for ; Thu, 14 May 2020 05:33:27 -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 1jZD2t-0006Lq-6u; Thu, 14 May 2020 14:33:03 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 7484A1004CE; Thu, 14 May 2020 14:33:02 +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 3 17/29] x86/entry: Convert Invalid Opcode exception to IDTENTRY In-Reply-To: References: <20200505134354.774943181@linutronix.de> <20200505134904.955511913@linutronix.de> Date: Thu, 14 May 2020 14:33:02 +0200 Message-ID: <87k11ezog1.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 7:15 AM Thomas Gleixner wrote: >> >> From: Thomas Gleixner >> >> Convert #UD to IDTENTRY: >> - Implement the C entry point with DEFINE_IDTENTRY >> - Emit the ASM stub with DECLARE_IDTENTRY >> - Remove the ASM idtentry in 64bit >> - Remove the open coded ASM entry code in 32bit >> - Fixup the XEN/PV code >> - Fixup the FOOF bug call in fault.c >> - Remove the old prototyoes >> >> No functional change. > > I think there *is* a functional change: > > >> --- a/arch/x86/mm/fault.c >> +++ b/arch/x86/mm/fault.c >> @@ -567,7 +567,7 @@ static int is_f00f_bug(struct pt_regs *r >> nr = (address - idt_descr.address) >> 3; >> >> if (nr == 6) { >> - do_invalid_op(regs, 0); >> + handle_invalid_op(regs); > > I suspect the old code was wrong and no one noticed because no one has > a F00F-buggy machine any more. I don't think so. It's really just the same thing. The old #UD C function was: void do_invalid_op(struct pt_regs *regs, long error_code) { do_error_trap(regs, error_code, "invalid opcode", X86_TRAP_UD, SIGILL, ILL_ILLOPN, (void __user *)uprobe_get_trap_addr(regs)); } after expanding the DO_ERROR() muck. The new one does: void handle_invalid_op(struct pt_regs *regs) { do_error_trap(regs, 0, "invalid opcode", X86_TRAP_UD, SIGILL, ILL_ILLOPN, error_get_trap_addr(regs)); } which is exactly the same except for the error code being hardcoded to zero in handle_invalid_op() because #UD does not have one. > So maybe document that you fixed up the F00F bug, too. Otherwise: Not sure what to document :) Thanks, tglx