From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Hogan Subject: Re: pt_regs leak into userspace (was Re: [PATCH v3 20/71] ARC: Signal handling) Date: Mon, 11 Feb 2013 10:28:06 +0000 Message-ID: <5118C7B6.6040807@imgtec.com> References: <1359024639-21915-1-git-send-email-vgupta@synopsys.com> <1359024639-21915-9-git-send-email-vgupta@synopsys.com> <51189D2F.4030000@synopsys.com> <5118C458.2070205@synopsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from multi.imgtec.com ([194.200.65.239]:26980 "EHLO multi.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755225Ab3BKK2L (ORCPT ); Mon, 11 Feb 2013 05:28:11 -0500 In-Reply-To: <5118C458.2070205@synopsys.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Vineet Gupta Cc: Jonas Bonn , Arnd Bergmann , "linux-arch@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Al Viro On 11/02/13 10:13, Vineet Gupta wrote: > On Monday 11 February 2013 03:06 PM, Jonas Bonn wrote: >> On 11 February 2013 08:26, Vineet Gupta wrote: >> >>> The only downside of this patch is that userspace signal stack grows in size, >>> since signal frame only cares about scratch regs (pt_regs), but has to accommodate >>> unused placeholder for callee regs too by virtue of using user_regs_struct. >> Is this really true? Don't setcontext and friends require that _all_ >> the registers be part of sigcontext? > > But for an ABI - callee saved regs will anyhow be saved/restored even in > setcontext case ! So collecting it for that purpose seems useless, or am I missing > something here. I think Jonas' point was that signals are asynchronous, i.e. you could get interrupted by a signal at virtually any time during the program's execution. Cheers James