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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,FAKE_REPLY_C,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 D5F0DC43331 for ; Thu, 26 Mar 2020 20:48:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 A37E02070A for ; Thu, 26 Mar 2020 20:48:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="AXyWPy9U"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="vkbsDVHf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A37E02070A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=FcomvzH35jbrLtekswHClGQlD3V16Ea+TKDX1bAXqGA=; b=AXyWPy9UpvTDlp h8ASeDL6PeJ2Pemp42u6jZBMeDX0AaAFBDyVkeU0RymylHHL1I0bpGUcHLlwIp6sDzVArHfi4LXax dchwedl4H0uIHVPfPDg1njdnchnPiNWRQ0DO9UYNdDFRBQKcncPploMdnXH+hTtv155JHNzaKP3mE VwjzI5PHJlNOvh3SjK3l72IREHQVFesbUg9Di3gGCMJM2AH8XJn0TvEnON/kFbWsRKWw/iYRe59nl 0G4HYgxEzfaSnVoqQRwmyv4YEBFYWPQKr0kgCt3x2G8Qn4xwER6tK9osGmk8eMYRPRN0xh05QH9Jc 8UV4+RvVCdiuRtHYI4DA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jHZQB-0000Km-Qi; Thu, 26 Mar 2020 20:48:11 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jHZQ9-0000KS-FX for linux-arm-kernel@lists.infradead.org; Thu, 26 Mar 2020 20:48:10 +0000 Received: from localhost (mobile-166-175-186-165.mycingular.net [166.175.186.165]) (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 B60FF2070A; Thu, 26 Mar 2020 20:48:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585255689; bh=6RKen0ioTy65oeuJuXAtJ6M2BJxU8YbCxuM+rKEX6NY=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=vkbsDVHff3CZYPxtxcc0HH1/CZg3CSmvig9OJyTv8xuiWi01uIYoBe5p1UK/juO07 W2cirk8UdPTFG/Fx2mEs/VvE9am3rbh8UJYQ7Dufa7Y1+2lSDW8ps9HN3qv87cQc1I XwxIrq10sk/x+sVNQpLiRH+unIfFfgKFXSCP8zwc= Date: Thu, 26 Mar 2020 15:48:07 -0500 From: Bjorn Helgaas To: Ray Jui Subject: Re: [PATCH 1/3] PCI: iproc: fix out of bound array access Message-ID: <20200326204807.GA87784@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4a836faf-645d-a1ab-d525-738a318758a0@broadcom.com> User-Agent: Mutt/1.12.2 (2019-09-21) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200326_134809_556806_958D4A2A X-CRM114-Status: GOOD ( 29.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Srinath Mannam , Florian Fainelli , Bharat Gooty , Ray Jui , linux-kernel@vger.kernel.org, Lorenzo Pieralisi , bcm-kernel-feedback-list@broadcom.com, linux-pci@vger.kernel.org, Andrew Murray , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Mar 26, 2020 at 01:27:36PM -0700, Ray Jui wrote: > On 3/26/2020 12:48 PM, Bjorn Helgaas wrote: > > ... > > It's outside the scope of this patch, but I'm not really a fan of the > > pcie->reg_offsets[] scheme this driver uses to deal with these > > differences. There usually seems to be *something* that keeps the > > driver from referencing registers that don't exist, but it doesn't > > seem like the mechanism is very consistent or robust: > > > > - IPROC_PCIE_LINK_STATUS is implemented by PAXB but not PAXC. > > iproc_pcie_check_link() avoids using it if "ep_is_internal", which > > is set for PAXC and PAXC_V2. Not an obvious connection. > > > > - IPROC_PCIE_CLK_CTRL is implemented for PAXB and PAXC_V1, but not > > PAXC_V2. iproc_pcie_perst_ctrl() avoids using it ep_is_internal", > > so it *doesn't* use it for PAXC_V1, which does implement it. > > Maybe a bug, maybe intentional; I can't tell. > > > > - IPROC_PCIE_INTX_EN is only implemented by PAXB (not PAXC), but > > AFAICT, we always call iproc_pcie_enable() and rely on > > iproc_pcie_write_reg() silently drop the write to it on PAXC. > > > > - IPROC_PCIE_OARR0 is implemented by PAXB and PAXB_V2 and used by > > iproc_pcie_map_ranges(), which is called if "need_ob_cfg", which > > is set if there's a "brcm,pcie-ob" DT property. No clear > > connection to PAXB. > > > > I think it would be more readable if we used a single variant > > identifier consistently, e.g., the "pcie->type" already used in > > iproc_pcie_msi_steer(), or maybe a set of variant-specific function > > pointers as pcie-qcom.c does. > > It is not possible to use a single variant identifier consistently, > i.e., 'pcie->type'. Many of these features are controller revision > specific, and certain revisions of the controllers may all have a > certain feature, while other revisions of the controllers do not. In > addition, there are overlap in features across different controllers. > > IMO, it makes sense to have feature specific flags or booleans, and have > those features enabled or disabled based on 'pcie->type', which is what > the current driver does, but like you pointed out, what the driver > failed is to do this consistently. There are several drivers that have the same problem of dealing with different revisions of hardware. It would be nice to do it in a consistent style, whatever that is. > The IPROC_PCIE_INTX_EN example you pointed out is a good example. I > agree with you that we shouldn't rely on iproc_pcie_write_reg to > silently drop the operation for PAXC. We should add code to make it > explictly obvious that legacy interrupt is not supported in all PAXC > controllers. > > pcie->pcie->reg_offsets[] scheme was not intended to be used to silently > drop register access that are activated based on features. It's a > mistake that should be fixed if some code in the driver is done that > way, as you pointed out. That's actually why I dug into this a bit -- the iproc_pcie_reg_is_invalid() case is really a design-time error, so it seemed like there should be a WARN() there instead of silently returning 0 or ignoring a write. Bjorn _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel