From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753509AbaJIJY2 (ORCPT ); Thu, 9 Oct 2014 05:24:28 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:59111 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750873AbaJIJYU (ORCPT ); Thu, 9 Oct 2014 05:24:20 -0400 Date: Thu, 9 Oct 2014 10:23:58 +0100 From: Will Deacon To: Kees Cook Cc: AKASHI Takahiro , Catalin Marinas , "dsaxena@linaro.org" , "arndb@arndb.de" , "linux-arm-kernel@lists.infradead.org" , "linaro-kernel@lists.linaro.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v7 1/6] arm64: ptrace: add PTRACE_SET_SYSCALL Message-ID: <20141009092358.GB3141@arm.com> References: <1412243176-16192-1-git-send-email-takahiro.akashi@linaro.org> <1412243176-16192-2-git-send-email-takahiro.akashi@linaro.org> <20141008141306.GQ26140@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 08, 2014 at 04:30:18PM +0100, Kees Cook wrote: > On Wed, Oct 8, 2014 at 9:13 AM, Will Deacon wrote: > > On Thu, Oct 02, 2014 at 10:46:11AM +0100, AKASHI Takahiro wrote: > >> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > >> index fe63ac5..2842f9f 100644 > >> --- a/arch/arm64/kernel/ptrace.c > >> +++ b/arch/arm64/kernel/ptrace.c > >> @@ -1082,7 +1082,19 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task) > >> long arch_ptrace(struct task_struct *child, long request, > >> unsigned long addr, unsigned long data) > >> { > >> - return ptrace_request(child, request, addr, data); > >> + int ret; > >> + > >> + switch (request) { > >> + case PTRACE_SET_SYSCALL: > >> + task_pt_regs(child)->syscallno = data; > >> + ret = 0; > >> + break; > >> + default: > >> + ret = ptrace_request(child, request, addr, data); > >> + break; > >> + } > >> + > >> + return ret; > >> } > > > > I still don't understand why this needs to be in arch-specific code. Can't > > we implement this in generic code and get architectures to implement > > something like syscall_set_nr if they want the generic interface? > > Personally, I'd rather see this land as-is in the arm64 tree, and then > later optimize PTRACE_SET_SYSCALL out of arm/ and arm64/, especially > since only these architectures implement this at the moment. Why? It should be really straightforward to do this in core code from the get-go and experience shows that, if we don't do it now, it will never happen. > This is my plan for the asm-generic seccomp.h too -- I'd rather avoid > touching other architectures in this series, as it's easier to review > this way. Then we can optimize the code in a separate series, which > will have those changes isolated, etc. But this doesn't need to touch any other architectures... Will