Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753043Ab2HVIcg (ORCPT ); Wed, 22 Aug 2012 04:32:36 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:48105 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751447Ab2HVIcd (ORCPT ); Wed, 22 Aug 2012 04:32:33 -0400 Date: Wed, 22 Aug 2012 14:02:25 +0530 From: Ananth N Mavinakayanahalli To: Oleg Nesterov Cc: Benjamin Herrenschmidt , linuxppc-dev@lists.ozlabs.org, lkml , Paul Mackerras , Anton Blanchard , michael@ellerman.id.au, Ingo Molnar , peterz@infradead.org, Srikar Dronamraju Subject: Re: [PATCH v3 2/2] powerpc: Uprobes port to powerpc Message-ID: <20120822083224.GC29216@in.ibm.com> Reply-To: ananth@in.ibm.com References: <20120726051902.GA29466@in.ibm.com> <20120726052029.GB29466@in.ibm.com> <20120815165931.GA10059@redhat.com> <1345066913.11751.4.camel@pasglop> <20120816050030.GA12060@in.ibm.com> <20120816152112.GA8874@redhat.com> <20120817051307.GA4782@in.ibm.com> <20120817150031.GA5029@redhat.com> <20120821112433.GB3519@in.ibm.com> <20120821130930.GA10382@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120821130930.GA10382@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12082208-1976-0000-0000-00001072C366 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1525 Lines: 42 On Tue, Aug 21, 2012 at 03:09:30PM +0200, Oleg Nesterov wrote: ... > > This is true for Intel like architectures that have *one* swbp > > instruction. On Powerpc, gdb for instance, can insert a trap variant at > > the address. Therefore, is_swbp_insn() by definition should return true > > for all trap variants. > > Not in this case, I think. > > OK, I was going to do this later, but this discussion makes me think > I should try to send the patch sooner. > > set_swbp()->is_swbp_at_addr() is simply unneeded and in fact should > be considered as unnecessary pessimization. > > set_orig_insn()->is_swbp_at_addr() makes more sense, but it can't fix > all races with userpace. Still it should die. > > > OK. I will separate out the is_swbp_insn() change into a separate patch. > > Great thanks. And if we remove is_swbp_insn() from set_swbp() and > set_orig_insn() then the semantics of is_swbp_insn() will much more > clear, and in this case I powerpc probably really needs to change it. Oleg, I have posted a new version for review [1] without the is_swbp_insn() change. I will await your changes around is_swbp_at_addr() and make changes to the powerpc code if necessary. Regards, Ananth [1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2012-August/100524.html -- 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/