From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57CA8C54FCB for ; Fri, 24 Apr 2020 13:24:33 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 086AF205C9 for ; Fri, 24 Apr 2020 13:24:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 086AF205C9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 497vz24Hf6zDr8V for ; Fri, 24 Apr 2020 23:24:30 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=srs0=19w6=6i=goodmis.org=rostedt@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=goodmis.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 497vwG73MWzDqVF for ; Fri, 24 Apr 2020 23:22:06 +1000 (AEST) Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 291E720767; Fri, 24 Apr 2020 13:22:04 +0000 (UTC) Date: Fri, 24 Apr 2020 09:22:02 -0400 From: Steven Rostedt To: Christophe Leroy Subject: Re: [PATCH 3/3] powerpc/kprobes: Check return value of patch_instruction() Message-ID: <20200424092202.71cfc549@gandalf.local.home> In-Reply-To: References: <3a132ac385340244b8d74179ac7bbbda7bf1f503.1587654213.git.naveen.n.rao@linux.vnet.ibm.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Naveen N. Rao" , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, 23 Apr 2020 17:41:52 +0200 Christophe Leroy wrote: > > diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c > > index 024f7aad1952..046485bb0a52 100644 > > --- a/arch/powerpc/kernel/optprobes.c > > +++ b/arch/powerpc/kernel/optprobes.c > > @@ -139,52 +139,67 @@ void arch_remove_optimized_kprobe(struct optimized_kprobe *op) > > } > > } > > > > +#define PATCH_INSN(addr, instr) \ > > +do { \ > > + int rc = patch_instruction((unsigned int *)(addr), instr); \ > > + if (rc) { \ > > + pr_err("%s:%d Error patching instruction at 0x%pK (%pS): %d\n", \ > > + __func__, __LINE__, \ > > + (void *)(addr), (void *)(addr), rc); \ > > + return rc; \ > > + } \ > > +} while (0) > > + > > I hate this kind of macro which hides the "return". > > What about keeping the return action in the caller ? > > Otherwise, what about implementing something based on the use of goto, > on the same model as unsafe_put_user() for instance ? #define PATCH_INSN(addr, instr) \ ({ int rc = patch_instruction((unsigned int *)(addr), instr); \ if (rc) \ pr_err("%s:%d Error patching instruction at 0x%pK (%pS): %d\n", \ __func__, __LINE__, \ (void *)(addr), (void *)(addr), rc); \ rc; \ }) Then you can just do: ret = PATCH_INSN(...); if (ret) return ret; in the code. -- Steve