From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754755Ab2B0UYO (ORCPT ); Mon, 27 Feb 2012 15:24:14 -0500 Received: from mail-lpp01m010-f46.google.com ([209.85.215.46]:53678 "EHLO mail-lpp01m010-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754605Ab2B0UYJ convert rfc822-to-8bit (ORCPT ); Mon, 27 Feb 2012 15:24:09 -0500 Authentication-Results: mr.google.com; spf=pass (google.com: domain of wad@chromium.org designates 10.112.25.8 as permitted sender) smtp.mail=wad@chromium.org; dkim=pass header.i=wad@chromium.org MIME-Version: 1.0 In-Reply-To: <20120227172208.GC10608@redhat.com> References: <1330140111-17201-1-git-send-email-wad@chromium.org> <1330140111-17201-8-git-send-email-wad@chromium.org> <20120227172208.GC10608@redhat.com> Date: Mon, 27 Feb 2012 14:24:04 -0600 Message-ID: Subject: Re: [PATCH v11 08/12] signal, x86: add SIGSYS info and make it synchronous. From: Will Drewry To: Oleg Nesterov Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, kernel-hardening@lists.openwall.com, netdev@vger.kernel.org, x86@kernel.org, arnd@arndb.de, davem@davemloft.net, hpa@zytor.com, mingo@redhat.com, peterz@infradead.org, rdunlap@xenotime.net, mcgrathr@chromium.org, tglx@linutronix.de, luto@mit.edu, eparis@redhat.com, serge.hallyn@canonical.com, djm@mindrot.org, scarybeasts@gmail.com, indan@nul.nu, pmoore@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, eric.dumazet@gmail.com, markus@chromium.org, coreyb@linux.vnet.ibm.com, keescook@chromium.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 27, 2012 at 11:22 AM, Oleg Nesterov wrote: > On 02/24, Will Drewry wrote: >> >> To ensure that SIGSYS delivery occurs on return from the triggering >> system call, SIGSYS is added to the SYNCHRONOUS_MASK macro. > > Hmm. Can't understand... please help. > >>  #define SYNCHRONOUS_MASK \ >>       (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \ >> -      sigmask(SIGTRAP) | sigmask(SIGFPE)) >> +      sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS)) > > Why? > > SYNCHRONOUS_MASK just tells dequeue_signal() "pick them first". > This is needed to make sure that the handler for, say SIGSEGV, > can use ucontext->ip as a faulting addr. I think that Roland covered this. (Since the syscall_rollback was called it's nice to let our handler get first go.) > But seccomp adds info->si_call_addr, this looks unneeded. True enough. I can drop it. It'd only be useful if the SIGSYS wasn't being forced and the signal was being handled without ucontext_t access. thanks!