Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753575Ab2FHEgc (ORCPT ); Fri, 8 Jun 2012 00:36:32 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:47154 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751884Ab2FHEga (ORCPT ); Fri, 8 Jun 2012 00:36:30 -0400 Date: Fri, 8 Jun 2012 10:06:05 +0530 From: Ananth N Mavinakayanahalli To: Jim Keniston Cc: Peter Zijlstra , Srikar Dronamraju , lkml , oleg@redhat.com, Paul Mackerras , Anton Blanchard , Ingo Molnar , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 2/2] [POWERPC] uprobes: powerpc port Message-ID: <20120608043605.GB13409@in.ibm.com> Reply-To: ananth@in.ibm.com References: <20120606091950.GB6745@in.ibm.com> <20120606092150.GC6745@in.ibm.com> <1338974822.2749.89.camel@twins> <20120606093541.GA29580@in.ibm.com> <1339006084.3458.25.camel@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1339006084.3458.25.camel@localhost> User-Agent: Mutt/1.5.17 (2007-11-01) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12060804-7606-0000-0000-000000F4E0AE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1256 Lines: 30 On Wed, Jun 06, 2012 at 11:08:04AM -0700, Jim Keniston wrote: > On Wed, 2012-06-06 at 15:05 +0530, Ananth N Mavinakayanahalli wrote: > > On Wed, Jun 06, 2012 at 11:27:02AM +0200, Peter Zijlstra wrote: > > > On Wed, 2012-06-06 at 14:51 +0530, Ananth N Mavinakayanahalli wrote: ... > > For the kernel, the only ones that are off limits are rfi (return from > > interrupt), mtmsr (move to msr). All other instructions can be probed. > > > > Both those instructions are supervisor level, so we won't see them in > > userspace at all; so we should be able to probe all user level > > instructions. > > Presumably rfi or mtmsr could show up in the instruction stream via an > erroneous or mischievous asm statement. It'd be good to verify that you > handle that gracefully. That'd be flagged elsewhere, by the architecture itself -- you'd get a privileged instruciton exception if you try execute any instruction not part of the UISA. I therefore don't think its a necessary check in the uprobes code. Ananth -- 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/