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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 94531C2D0C9 for ; Thu, 12 Dec 2019 05:40:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 626B922527 for ; Thu, 12 Dec 2019 05:40:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576129255; bh=XKhjZZ9Eq3LmyvLJDZblqLMH57FvHvbebLAz9KXwU2k=; h=From:To:Cc:Subject:Date:List-ID:From; b=VEe4YJrZ7AR4/sgRlH358r8VqmtxAUH848nmf3De73kaHNzDx6/C3Ym4Vibtl6pmc YczakDaiZWbB0gPd6eURnWPyBYqfLOoxGwr8/Z9EjyCH6ymRxFmB2H8y9961HFKekc SumXSZkkM8SB1W1c713CkOZIsrVgkASEhm6anoCw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726945AbfLLFky (ORCPT ); Thu, 12 Dec 2019 00:40:54 -0500 Received: from mail.kernel.org ([198.145.29.99]:42040 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725980AbfLLFkx (ORCPT ); Thu, 12 Dec 2019 00:40:53 -0500 Received: from wens.tw (mirror2.csie.ntu.edu.tw [140.112.30.76]) (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 DD5222073D; Thu, 12 Dec 2019 05:40:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576129253; bh=XKhjZZ9Eq3LmyvLJDZblqLMH57FvHvbebLAz9KXwU2k=; h=From:To:Cc:Subject:Date:From; b=v4W7GJCoMDjbUoNwzl5rFXo6Rm9FMwzTk1iO/Zp3tV5G2mHEiwaOm+rVPv2lbol/R Hnugq+Iv8ilTrctbmt8hp9WkayBXkvi7K0Kx9ANLLsEKrxyw4so75fBMAx+O0JL49I qeGr9mdPtLWNTdNNeghUczai3+QdIOhHa/n9giXs= Received: by wens.tw (Postfix, from userid 1000) id AF8D75FB77; Thu, 12 Dec 2019 13:40:50 +0800 (CST) From: Chen-Yu Tsai To: Russell King Cc: Chen-Yu Tsai , Christoph Hellwig , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v2] ARM: dma-api: fix max_pfn off-by-one error in __dma_supported() Date: Thu, 12 Dec 2019 13:40:47 +0800 Message-Id: <20191212054047.26202-1-wens@kernel.org> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chen-Yu Tsai max_pfn, as set in arch/arm/mm/init.c: static void __init find_limits(unsigned long *min, unsigned long *max_low, unsigned long *max_high) { *max_low = PFN_DOWN(memblock_get_current_limit()); *min = PFN_UP(memblock_start_of_DRAM()); *max_high = PFN_DOWN(memblock_end_of_DRAM()); } with memblock_end_of_DRAM() pointing to the next byte after DRAM. As such, max_pfn points to the PFN after the end of DRAM. Thus when using max_pfn to check DMA masks, we should subtract one when checking DMA ranges against it. Commit 8bf1268f48ad ("ARM: dma-api: fix off-by-one error in __dma_supported()") fixed the same issue, but missed this spot. This issue was found while working on the sun4i-csi v4l2 driver on the Allwinner R40 SoC. On Allwinner SoCs, DRAM is offset at 0x40000000, and we are starting to use of_dma_configure() with the "dma-ranges" property in the device tree to have the DMA API handle the offset. In this particular instance, dma-ranges was set to the same range as the actual available (2 GiB) DRAM. The following error appeared when the driver attempted to allocate a buffer: sun4i-csi 1c09000.csi: Coherent DMA mask 0x7fffffff (pfn 0x40000-0xc0000) covers a smaller range of system memory than the DMA zone pfn 0x0-0xc0001 sun4i-csi 1c09000.csi: dma_alloc_coherent of size 307200 failed Fixing the off-by-one error makes things work. Fixes: 11a5aa32562e ("ARM: dma-mapping: check DMA mask against available memory") Fixes: 9f28cde0bc64 ("ARM: another fix for the DMA mapping checks") Fixes: ab746573c405 ("ARM: dma-mapping: allow larger DMA mask than supported") Cc: Signed-off-by: Chen-Yu Tsai --- Changes since v1: - correct max_pfn offset in the correct place. --- arch/arm/mm/dma-mapping.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index e822af0d9219..9414d72f664b 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -221,7 +221,7 @@ EXPORT_SYMBOL(arm_coherent_dma_ops); static int __dma_supported(struct device *dev, u64 mask, bool warn) { - unsigned long max_dma_pfn = min(max_pfn, arm_dma_pfn_limit); + unsigned long max_dma_pfn = min(max_pfn - 1, arm_dma_pfn_limit); /* * Translate the device's DMA mask to a PFN limit. This -- 2.24.0