From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.190]) by ozlabs.org (Postfix) with ESMTP id ACFD667B59 for ; Thu, 17 Aug 2006 00:43:38 +1000 (EST) Received: by nf-out-0910.google.com with SMTP id p48so625761nfa for ; Wed, 16 Aug 2006 07:43:36 -0700 (PDT) Message-ID: <787b0d920608160743t60ba42b7m5dd1426e0ee1f576@mail.gmail.com> Date: Wed, 16 Aug 2006 10:43:36 -0400 From: "Albert Cahalan" To: "Paul Mackerras" Subject: Re: PowerPC paxtest results w/ gcc-4.1 In-Reply-To: <17634.64640.709200.871907@cargo.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed References: <17630.27174.711916.643790@cargo.ozlabs.ibm.com> <000301c6bf97$e9151e00$99dfdfdf@bakuhatsu.net> <17633.18057.778991.483461@cargo.ozlabs.ibm.com> <20060816105925.GB21865@iram.es> <17634.64640.709200.871907@cargo.ozlabs.ibm.com> Cc: debian-powerpc@lists.debian.org, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 8/16/06, Paul Mackerras wrote: > Gabriel Paubert writes: > > BTW, there is one way to make pages non executable: mark > > them as guarded, but it will have a significant cost in > > terms of performance. > > Indeed. I guess we could do that as a config option for machines that > really want maximum security at the expense of performance, but I > don't think all users would want that. On the other hand, if you want to squeeze some performance out of the chip, turn off coherency. (probably not for SMP) I've done it before, with a non-Linux OS. It does help. Other tricks are to map userspace via BATs and, on the 7410 at least, to map half or all of the outermost cache memory as a special block of high-speed memory.