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)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 5316ADDFE9 for ; Sat, 7 Jul 2007 12:33:38 +1000 (EST) Subject: Re: Executing from readablee, no-exec pages From: Benjamin Herrenschmidt To: David Woodhouse In-Reply-To: <1183732922.2747.36.camel@shinybook.infradead.org> References: <468D68D4.4050704@freescale.com> <1183732922.2747.36.camel@shinybook.infradead.org> Content-Type: text/plain Date: Sat, 07 Jul 2007 12:33:00 +1000 Message-Id: <1183775580.3388.191.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, paulus@samba.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2007-07-06 at 10:42 -0400, David Woodhouse wrote: > On Thu, 2007-07-05 at 16:55 -0500, Scott Wood wrote: > > To maintain compatibility with these versions, we could change the test > > in do_page_fault() to include VM_READ as well as VM_EXEC on targets that > > don't have a separate exec-bit in hardware (are there any powerpc mmus > > that do?). > > 64-bit implementations since POWER4 have separate exec permissions, > don't they? So any userspace which tries to execute non-executable pages > is already broken when running on a ppc64 machine; I wouldn't worry too > much about letting it break on ppc32 too. > > We already use vDSO signal trampolines even on the 32-bit kernel, right? The problem was with old glibc 32 bits which used to jump to an instruction in the .got iirc that wasn't in an executable section Ben.