From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e31.co.us.ibm.com (e31.co.us.ibm.com [32.97.110.149]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e31.co.us.ibm.com", Issuer "Equifax" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 1676CB6FA3 for ; Fri, 8 Jun 2012 16:06:12 +1000 (EST) Received: from /spool/local by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 8 Jun 2012 00:06:10 -0600 Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 68E3819D804F for ; Fri, 8 Jun 2012 06:06:06 +0000 (WET) Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q586672K189614 for ; Fri, 8 Jun 2012 00:06:07 -0600 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q58666sc011574 for ; Fri, 8 Jun 2012 00:06:06 -0600 Date: Fri, 8 Jun 2012 11:31:04 +0530 From: Ananth N Mavinakayanahalli To: Michael Ellerman Subject: Re: [PATCH 2/2] [POWERPC] uprobes: powerpc port Message-ID: <20120608060104.GD13409@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> <20120608043605.GB13409@in.ibm.com> <1339134714.25573.4.camel@concordia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1339134714.25573.4.camel@concordia> Cc: Jim Keniston , Srikar Dronamraju , Peter Zijlstra , lkml , oleg@redhat.com, Paul Mackerras , Anton Blanchard , Ingo Molnar , linuxppc-dev@lists.ozlabs.org Reply-To: ananth@in.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Jun 08, 2012 at 03:51:54PM +1000, Michael Ellerman wrote: > On Fri, 2012-06-08 at 10:06 +0530, Ananth N Mavinakayanahalli wrote: > > 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. > > But you're not executing the instruction, you're passing it to > emulate_step(). Or am I missing something? But MSR_PR=1 and hence emulate_step() will return -1 and hence we will end up single-stepping using user_enable_single_step(). Same with rfid. Ananth