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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, 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 CB94BC43381 for ; Mon, 18 Mar 2019 14:59:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A384520850 for ; Mon, 18 Mar 2019 14:59:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727844AbfCRO7S (ORCPT ); Mon, 18 Mar 2019 10:59:18 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:35844 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726731AbfCRO7R (ORCPT ); Mon, 18 Mar 2019 10:59:17 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 01F531650; Mon, 18 Mar 2019 07:59:17 -0700 (PDT) Received: from e107155-lin (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0DE063F59C; Mon, 18 Mar 2019 07:59:13 -0700 (PDT) Date: Mon, 18 Mar 2019 14:59:11 +0000 From: Sudeep Holla To: "Dmitry V. Levin" Cc: x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Catalin Marinas , Will Deacon , Oleg Nesterov , 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: <20190318145911.GC18196@e107155-lin> References: <20190318104925.16600-1-sudeep.holla@arm.com> <20190318104925.16600-5-sudeep.holla@arm.com> <20190318142618.GA27941@altlinux.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190318142618.GA27941@altlinux.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 18, 2019 at 05:26:18PM +0300, Dmitry V. Levin wrote: > On Mon, Mar 18, 2019 at 10:49:23AM +0000, Sudeep Holla wrote: > > Now that we have a new hook ptrace_syscall_enter that can be called from > > syscall entry code and it handles PTRACE_SYSEMU in generic code, we > > can do some cleanup using the same in do_syscall_trace_enter. > > > > Cc: Oleg Nesterov > > Cc: Paul Mackerras > > Cc: Michael Ellerman > > Signed-off-by: Sudeep Holla > > --- > > arch/powerpc/kernel/ptrace.c | 48 ++++++++++++++++-------------------- > > 1 file changed, 21 insertions(+), 27 deletions(-) > > > > diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c > > index 2e2183b800a8..05579a5dcb12 100644 > > --- a/arch/powerpc/kernel/ptrace.c > > +++ b/arch/powerpc/kernel/ptrace.c > > @@ -3278,35 +3278,29 @@ long do_syscall_trace_enter(struct pt_regs *regs) > > > > user_exit(); > > > > - flags = READ_ONCE(current_thread_info()->flags) & > > - (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE); > > - > > - if (flags) { > > - int rc = tracehook_report_syscall_entry(regs); > > + if (unlikely(ptrace_syscall_enter(regs))) { > > + /* > > + * A nonzero return code from tracehook_report_syscall_entry() > > + * tells us to prevent the syscall execution, but we are not > > + * going to execute it anyway. > > + * > > + * Returning -1 will skip the syscall execution. We want to > > + * avoid clobbering any registers, so we don't goto the skip > > + * label below. > > + */ > > + return -1; > > + } > > This comment is out of sync with the changed code. Still applicable indirectly as ptrace_syscall_enter just executes tracehook_report_syscall_entry, but I agree needs rewording, will update. -- Regards, Sudeep