Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754899Ab1DUQ2R (ORCPT ); Thu, 21 Apr 2011 12:28:17 -0400 Received: from toast.topped-with-meat.com ([204.197.218.159]:34531 "EHLO topped-with-meat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754769Ab1DUQ2Q (ORCPT ); Thu, 21 Apr 2011 12:28:16 -0400 X-Greylist: delayed 371 seconds by postgrey-1.27 at vger.kernel.org; Thu, 21 Apr 2011 12:28:16 EDT MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Eric Paris X-Fcc: ~/Mail/lkml Cc: Srikar Dronamraju , Eric Paris , Peter Zijlstra , Ingo Molnar , Steven Rostedt , Linux-mm , Linus Torvalds , Jonathan Corbet , Masami Hiramatsu , Thomas Gleixner , Ananth N Mavinakayanahalli , Oleg Nesterov , Andrew Morton , SystemTap , Jim Keniston , Andi Kleen , LKML , sds@tycho.nsa.gov Subject: Re: [PATCH v3 2.6.39-rc1-tip 12/26] 12: uprobes: slot allocation for uprobes In-Reply-To: Eric Paris's message of Thursday, 21 April 2011 10:45:33 -0400 <1303397133.1708.41.camel@unknown001a4b0c2895> References: <20110401143223.15455.19844.sendpatchset@localhost6.localdomain6> <20110401143457.15455.64839.sendpatchset@localhost6.localdomain6> <1303145171.32491.886.camel@twins> <20110419062654.GB10698@linux.vnet.ibm.com> <20110421141125.GG10698@linux.vnet.ibm.com> <1303397133.1708.41.camel@unknown001a4b0c2895> X-Zippy-Says: Half a mind is a terrible thing to waste! Message-Id: <20110421161442.61A532C15B@topped-with-meat.com> Date: Thu, 21 Apr 2011 09:14:42 -0700 (PDT) X-CMAE-Score: 0 X-CMAE-Analysis: v=2.0 cv=MoMpGxme c=1 sm=1 a=GAGUJ4Jf488A:10 a=kj9zAlcOel0A:10 a=-QHIz3BqkMX5BjEzqIgA:9 a=CjuIK1q_8ugA:10 a=WkljmVdYkabdwxfqvArNOQ==:117 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 909 Lines: 20 > Unrelated note: I'd prefer to see that page be READ+EXEC only once it > has been mapped into the victim task. Obviously the portion of the code > that creates this page and sets up the instructions to run is going to > need write. Maybe this isn't feasible. Maybe this magic pages gets > written a lot even after it's been mapped in. But I'd rather, if > possible, know that my victim tasks didn't have a WRITE+EXEC page > available...... AIUI the page never really needs to be writable in the page tables. It's never written from user mode. It's only written by kernel code, and that can use a separate momentary kmap to do its writing. Thanks, Roland -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/