From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3wqG113ymhzDqMS for ; Sat, 17 Jun 2017 08:55:17 +1000 (AEST) Message-ID: <1497653684.2897.104.camel@kernel.crashing.org> Subject: Re: [RFC PATCH 7/7 v1]powerpc: Deliver SEGV signal on protection key violation. From: Benjamin Herrenschmidt To: Ram Pai Cc: Anshuman Khandual , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, dave.hansen@intel.com, paulus@samba.org, aneesh.kumar@linux.vnet.ibm.com Date: Sat, 17 Jun 2017 08:54:44 +1000 In-Reply-To: <20170616191537.GB17588@ram.oc3035372033.ibm.com> References: <1496711109-4968-1-git-send-email-linuxram@us.ibm.com> <1496711109-4968-8-git-send-email-linuxram@us.ibm.com> <622d7abf-3d99-8897-5afb-ef8c4f950fc0@linux.vnet.ibm.com> <1497609181.2897.100.camel@kernel.crashing.org> <20170616191537.GB17588@ram.oc3035372033.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2017-06-16 at 12:15 -0700, Ram Pai wrote: > gp_regs size is not changed, nor is the layout. A unused field in > the gp_regs is used to fill in the AMR contents. Old binaries will not > be knowing about this unused field, and hence should not break. > > New binaries can leverage this already existing but newly defined > field; to read the contents of AMR. > > Is it still a concern? Calls to sys_swapcontext with a made-up context will end up with a crap AMR if done by code who didn't know about that register. Ben.