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=-3.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 8664EC5CFFE for ; Mon, 10 Dec 2018 13:30:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 568E42084E for ; Mon, 10 Dec 2018 13:30:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 568E42084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727558AbeLJNa3 (ORCPT ); Mon, 10 Dec 2018 08:30:29 -0500 Received: from vmicros1.altlinux.org ([194.107.17.57]:41572 "EHLO vmicros1.altlinux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727527AbeLJNa2 (ORCPT ); Mon, 10 Dec 2018 08:30:28 -0500 Received: from mua.local.altlinux.org (mua.local.altlinux.org [192.168.1.14]) by vmicros1.altlinux.org (Postfix) with ESMTP id CAADB72CC66; Mon, 10 Dec 2018 16:30:25 +0300 (MSK) Received: by mua.local.altlinux.org (Postfix, from userid 508) id BF0CC7CF1FC; Mon, 10 Dec 2018 16:30:25 +0300 (MSK) Date: Mon, 10 Dec 2018 16:30:25 +0300 From: "Dmitry V. Levin" To: Geert Uytterhoeven Cc: Oleg Nesterov , Andy Lutomirski , lineprinter@altlinux.org, Eugene Syromiatnikov , linux-m68k , Linux Kernel Mailing List Subject: Re: [PATCH v5 13/25] m68k: add asm/syscall.h Message-ID: <20181210133025.GG11942@altlinux.org> References: <20181210042352.GA6092@altlinux.org> <20181210043010.GM6131@altlinux.org> <20181210124059.GA11942@altlinux.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="xB0nW4MQa6jZONgY" Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --xB0nW4MQa6jZONgY Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Geert, On Mon, Dec 10, 2018 at 02:06:28PM +0100, Geert Uytterhoeven wrote: > On Mon, Dec 10, 2018 at 1:41 PM Dmitry V. Levin wrote: > > On Mon, Dec 10, 2018 at 09:45:42AM +0100, Geert Uytterhoeven wrote: > > > On Mon, Dec 10, 2018 at 5:30 AM Dmitry V. Levin wr= ote: > > > > syscall_get_* functions are required to be implemented on all > > > > architectures in order to extend the generic ptrace API with > > > > PTRACE_GET_SYSCALL_INFO request. > > > > > > > > This introduces asm/syscall.h on m68k implementing all 5 syscall_ge= t_* > > > > functions as documented in asm-generic/syscall.h: syscall_get_nr, > > > > syscall_get_arguments, syscall_get_error, syscall_get_return_value, > > > > and syscall_get_arch. > > > > > > > > Cc: Geert Uytterhoeven > > > > Cc: Oleg Nesterov > > > > Cc: Andy Lutomirski > > > > Cc: Elvira Khabirova > > > > Cc: Eugene Syromyatnikov > > > > Cc: linux-m68k@lists.linux-m68k.org > > > > Signed-off-by: Dmitry V. Levin > > > > --- > > > > > > > > Notes: > > > > v5: added syscall_get_nr, syscall_get_arguments, syscall_get_er= ror, > > > > and syscall_get_return_value > > > > v1: added syscall_get_arch > > > > > > > --- /dev/null > > > > +++ b/arch/m68k/include/asm/syscall.h > > > > @@ -0,0 +1,39 @@ > > > > > > > +static inline void > > > > +syscall_get_arguments(struct task_struct *task, struct pt_regs *re= gs, > > > > + unsigned int i, unsigned int n, unsigned long= *args) > > > > +{ > > > > + BUG_ON(i + n > 6); > > > > > > Does this have to crash the kernel? > > > > This is what most of other architectures do, but we could choose > > a softer approach, e.g. use WARN_ON_ONCE instead. > > > > > Perhaps you can return an error code instead? > > > > That would be problematic given the signature of this function > > and the nature of the potential bug which would most likely be a usage = error. >=20 > Of course to handle that, the function's signature need to be changed. > Changing it has the advantage that the error handling can be done at the > caller, in common code, instead of duplicating it for all > architectures, possibly > leading to different semantics. Given that *all* current users of syscall_get_arguments specify i =3D=3D 0 (and there is an architecture that has BUG_ON(i)),=20 it should be really a usage error to get into situation where i + n > 6, I wish a BUILD_BUG_ON could be used here instead. I don't think it worths pushing the change of API just to convert a "cannot happen" assertion into an error that would have to be dealt with on the caller side. --=20 ldv --xB0nW4MQa6jZONgY Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIcBAEBCAAGBQJcDmpxAAoJEAVFT+BVnCUI3DcP/j4lZGNykTpZLphxgSp27Zaa VWC5E6e/HM1tH0RqIfRsYAmS1m15cYDG1MaoohsIMKUi0gzfXhJm/LCTbRlwQBKT KA3c+NL7i0DYX5wo08BZbe33LkeHZxPrLbDV5lrJvEHV7M1U2QUSSZqvyqpcDes1 B3UGaYtnngHgK9E/WntEoPCibtVi7ThGWHohZQcoBtwvc9PX5t5wW3CDFsOxwMol U1mGpMoyP8UYLF7WRfCBR+ESTTO9FB/Q0EBSfZXBjACAjQl4Ut2+VpgiBvJe/WDg YbluyEoTDntS+tirjr5heZOSqq5RgjszRjiw4R86pgsZhZ6xg9SNKcUA0h3AQvVg 6DGQvgW3clt7po37gyJhqJww0FzOrZYLz9z2fy03koHwxY5hY3oDJzXcrSrxqRNB VeNri5epY2mHIwgiOrjvqfnAN8A783PA1it/+S7ENj8SNgdDi1gJXLJMskOvvBWE kxecuPGb+M9BvU2dKo1VpD6oRIKZYIDq3s+w9sFo7nCgINNE7Eo0I/ljRVwMNEOQ rBcSVpMHr/EoWrGUpt6/EG3MsDsM0FoNuF3PObXsyYo7uE6yMeGU3AVJd7hpIzcC TF+PVtAUP4IOIjSqu4N+GA3vGrqUjzc09xTKtNAj9m27gLteik+2oOhzY28wWchZ f5P8a3qjNTe6/pFWd18w =iMqD -----END PGP SIGNATURE----- --xB0nW4MQa6jZONgY--