Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755463Ab2FFJfx (ORCPT ); Wed, 6 Jun 2012 05:35:53 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:56274 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750713Ab2FFJfu (ORCPT ); Wed, 6 Jun 2012 05:35:50 -0400 Date: Wed, 6 Jun 2012 15:05:41 +0530 From: Ananth N Mavinakayanahalli To: Peter Zijlstra Cc: linuxppc-dev@lists.ozlabs.org, lkml , Paul Mackerras , benh@kernel.crashing.org, Srikar Dronamraju , Anton Blanchard , Ingo Molnar , oleg@redhat.com Subject: Re: [PATCH 2/2] [POWERPC] uprobes: powerpc port Message-ID: <20120606093541.GA29580@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1338974822.2749.89.camel@twins> User-Agent: Mutt/1.5.17 (2007-11-01) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12060609-7182-0000-0000-000001AD07B7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1354 Lines: 31 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: > > One TODO in this port compared to x86 is the uprobe abort_xol() logic. > > x86 depends on the thread_struct.trap_nr (absent in powerpc) to determine > > if a signal was caused when the uprobed instruction was single-stepped/ > > emulated, in which case, we reset the instruction pointer to the probed > > address and retry the probe again. > > Another curious difference is that x86 uses an instruction decoder and > contains massive tables to validate we can probe a particular > instruction. > > Can we probe all possible PPC instructions? 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. I am not aware of specific caveats for vector/altivec instructions; maybe Paul or Ben are more suitable to comment on that. 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/