From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14556 invoked by alias); 28 Feb 2012 08:49:07 -0000 Received: (qmail 14547 invoked by uid 22791); 28 Feb 2012 08:49:05 -0000 X-SWARE-Spam-Status: No, hits=-2.0 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx3.mail.elte.hu (HELO mx3.mail.elte.hu) (157.181.1.138) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 28 Feb 2012 08:48:52 +0000 Received: from elvis.elte.hu ([157.181.1.14]) by mx3.mail.elte.hu with esmtp (Exim) id 1S2Ijb-0007KW-8n from ; Tue, 28 Feb 2012 09:48:44 +0100 Received: by elvis.elte.hu (Postfix, from userid 1004) id 726D83E2596; Tue, 28 Feb 2012 09:48:24 +0100 (CET) Date: Tue, 28 Feb 2012 08:49:00 -0000 From: Ingo Molnar To: Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, yrl.pp-manager.tt@hitachi.com, systemtap@sourceware.org, anderson@redhat.com, Thomas Gleixner , "H. Peter Anvin" , Ananth N Mavinakayanahalli Subject: Re: Re: [PATCH v3 -tip] [BUGFIX] x86/kprobes: Fix to recover instructions on optimized path Message-ID: <20120228084828.GK21106@elte.hu> References: <20120223083703.GA26781@elte.hu> <20120224095412.8462.55698.stgit@localhost.localdomain> <20120227093421.GA10078@elte.hu> <4F4C4182.1040706@hitachi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F4C4182.1040706@hitachi.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=AWL,BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] 0.0 AWL AWL: From: address is in the auto white-list X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2012-q1/txt/msg00208.txt.bz2 * Masami Hiramatsu wrote: > (2012/02/27 18:34), Ingo Molnar wrote: > > > > * Masami Hiramatsu wrote: > > > >> + > >> +#ifdef CONFIG_OPTPROBES > >> +static unsigned long __recover_optprobed_insn(struct kprobe *kp, > >> + kprobe_opcode_t *buf, > >> + unsigned long addr) > >> +{ > >> + long offs = addr - (unsigned long)kp->addr - 1; > >> + struct optimized_kprobe *op = container_of(kp, struct optimized_kprobe, kp); > >> + > >> + /* > >> + * If the kprobe can be optimized, original bytes which can be > >> + * overwritten by jump destination address. In this case, original > >> + * bytes must be recovered from op->optinsn.copied_insn buffer. > >> + */ > >> + memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); > >> + if (addr == (unsigned long)kp->addr) { > >> + buf[0] = kp->opcode; > >> + memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE); > >> + } else > >> + memcpy(buf, op->optinsn.copied_insn + offs, RELATIVE_ADDR_SIZE - offs); > >> + > >> + return (unsigned long)buf; > >> +} > >> +#endif > > > > Why not stick this into a new kprobes-opt.c file? > > Would you mean that I should split all optprobe stuffs into > new file? Yeah, that would be sensible I think - and it might help avoid similar complications in the future. Could (and probably should) be done in a separate patch - to keep the bits that you already fixed and tested intact. > > This should be a separate, kprobes_recover_opt() method and > > be inside kprobes-opt.c as well. > > OK, I'll do that. But I think it should be separated work. > Just for the bugfix, I think this should go into this style, > because this should be pushed into stable tree too. I don't think we can push such a large and complex looking patch into v3.3 (let alone into -stable) - it's v3.4 material, and that's why I asked for the cleaner split-out as well. This optprobes code is really non-obvious at the moment and a split-out might improve that and might make future fixes easier to merge. Thanks, Ingo