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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 29F95C43381 for ; Tue, 19 Mar 2019 17:32:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F2E6E20811 for ; Tue, 19 Mar 2019 17:32:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727537AbfCSRci (ORCPT ); Tue, 19 Mar 2019 13:32:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44130 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726579AbfCSRci (ORCPT ); Tue, 19 Mar 2019 13:32:38 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D31DD81E09; Tue, 19 Mar 2019 17:32:37 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.34]) by smtp.corp.redhat.com (Postfix) with SMTP id 5E04B5DA2A; Tue, 19 Mar 2019 17:32:34 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 19 Mar 2019 18:32:37 +0100 (CET) Date: Tue, 19 Mar 2019 18:32:33 +0100 From: Oleg Nesterov To: Sudeep Holla Cc: x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Catalin Marinas , Will Deacon , Paul Mackerras , Michael Ellerman , Thomas Gleixner , Ingo Molnar , Richard Weinberger , jdike@addtoit.com, Steve Capper , Haibo Xu , Bin Lu , Andy Lutomirski Subject: Re: [PATCH v2 4/6] powerpc: use common ptrace_syscall_enter hook to handle _TIF_SYSCALL_EMU Message-ID: <20190319173233.GB11525@redhat.com> References: <20190318104925.16600-1-sudeep.holla@arm.com> <20190318104925.16600-5-sudeep.holla@arm.com> <20190318172024.GB23521@redhat.com> <20190318172457.GD18196@e107155-lin> <20190318173341.GD23521@redhat.com> <20190318174028.GE18196@e107155-lin> <20190319170804.GA11525@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190319170804.GA11525@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Tue, 19 Mar 2019 17:32:38 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/19, Oleg Nesterov wrote: > > Well, personally I see no point... Again, after the trivial simplification > x86 does > > if (work & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { > ret = tracehook_report_syscall_entry(regs); > if (ret || (work & _TIF_SYSCALL_EMU)) > return -1L; > } > > this looks simple enough for copy-and-paste. > > > If there's a better way to achieve the same > > I can only say that if we add a common helper, I think it should absorb > tracehook_report_syscall_entry() and handle both TIF's just like the code > above does. Not sure this makes any sense. this won't work, looking at 6/6 I see that arm64 needs to distinguish _TRACE and _EMU ... I don't understand this code, but it looks suspicious. If tracehook_report_syscall_entry() returns nonzero the tracee was killed, syscall_trace_enter() should just return. To me this is another indication that consolidation makes no sense ;) Oleg.