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[2620:137:e000::1:20]) by mx.google.com with ESMTP id me15-20020a17090b17cf00b00263fc986e28si15913189pjb.24.2023.07.25.11.36.39; Tue, 25 Jul 2023 11:36:52 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@chromium.org header.s=google header.b=mdgqGoEy; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232289AbjGYSDk (ORCPT + 99 others); Tue, 25 Jul 2023 14:03:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230313AbjGYSDi (ORCPT ); Tue, 25 Jul 2023 14:03:38 -0400 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 611361FDE for ; Tue, 25 Jul 2023 11:03:36 -0700 (PDT) Received: by mail-pl1-x632.google.com with SMTP id d9443c01a7336-1bbc2e1c6b2so4550875ad.3 for ; Tue, 25 Jul 2023 11:03:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1690308216; x=1690913016; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=A3wk98CPhmXaucfW3yFy0X9veK7c7V/LOvkjR4lZXDk=; b=mdgqGoEyde5ufR0v0DwdbxwxdHa372uxZ0WCuZCPFnP2tWnW3cD+aRMsF3UhDkW2W8 JRNRLtjBkoPm/8J+2v8HL3qRmFef49+Bom+JO5Ec/knUI7wtUTiCn7WGM+yUu0pprK9T lf5uswnmIi0XpGMFOBgRcHhnhqrYFfANyRFJY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690308216; x=1690913016; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=A3wk98CPhmXaucfW3yFy0X9veK7c7V/LOvkjR4lZXDk=; b=TbLYKz23yAIFe0FTjYthClu4bmY8uO5Gvu2IYnMaPz4w5wuyN2uSf4DzWjcAOYuaL2 r3GdbT9KByRUBe5X7BFwKFu2QNNuGkDHIOJur+cijzsTbQeWHBLFTqjRQegB20WIjUjD u2ZbqV2QVOOcAPQnR01pcxQVC2vaIi2mEPLcYWDa0Xk/HQwC/mEgsw6nwTLu66fWhQ0e QhTuagWh41KSQ1Cu+zXfpY41o6iZfqTE21M/2QM4IperMb7xrPpJxjLts9n+Nm2p8Z93 QFeBkY84hDuPBKLxndhhIpGAv+yQ4iVnsGeb9woHcUGVwslZa0RQVnpi9ErkKFpGzHo0 EX0Q== X-Gm-Message-State: ABy/qLZda9OtWv2hG6Pc3Y+iEJDSILaKcvgOvdaVBncBi0VVYv2+PGgj 59L9NzBDzPzFYcrlkgRxa6VXlg== X-Received: by 2002:a17:902:d487:b0:1b8:8069:d432 with SMTP id c7-20020a170902d48700b001b88069d432mr23474plg.16.1690308215805; Tue, 25 Jul 2023 11:03:35 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:9d:2:c363:4681:f5b8:301]) by smtp.gmail.com with ESMTPSA id jl14-20020a170903134e00b001b54a88e4a6sm11305254plb.51.2023.07.25.11.03.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Jul 2023 11:03:35 -0700 (PDT) From: Douglas Anderson To: Mark Brown Cc: Vijaya Krishna Nivarthi , Douglas Anderson , Andy Gross , Bjorn Andersson , Konrad Dybcio , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: [PATCH 1/2] spi: spi-qcom-qspi: Fallback to PIO for xfers that aren't multiples of 4 bytes Date: Tue, 25 Jul 2023 11:02:26 -0700 Message-ID: <20230725110226.1.Ia2f980fc7cd0b831e633391f0bb1272914d8f381@changeid> X-Mailer: git-send-email 2.41.0.487.g6d72f3e995-goog MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1772418721145286497 X-GMAIL-MSGID: 1772418721145286497 The Qualcomm QSPI driver appears to require that any reads using DMA are a mutliple of 4 bytes. If this isn't true then the controller will clobber any extra bytes in memory following the last word. Let's detect this and falback to PIO. This fixes problems reported by slub_debug=FZPUA, which would complain about "kmalloc Redzone overwritten". One such instance said: 0xffffff80c29d541a-0xffffff80c29d541b @offset=21530. First byte 0x0 instead of 0xcc Allocated in mtd_kmalloc_up_to+0x98/0xac age=36 cpu=3 pid=6658 Tracing through what was happening I saw that, while we often did DMA tranfers of 0x1000 bytes, sometimes we'd end up doing ones of 0x41a bytes. Those 0x41a byte transfers were the problem. NOTE: a future change will enable the SPI "mem ops" to help avoid this case, but it still seems good to add the extra check in the transfer. Fixes: b5762d95607e ("spi: spi-qcom-qspi: Add DMA mode support") Signed-off-by: Douglas Anderson Reviewed-by: Bjorn Andersson Reviewed-by: Vijaya Krishna Nivarthi --- drivers/spi/spi-qcom-qspi.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/spi/spi-qcom-qspi.c b/drivers/spi/spi-qcom-qspi.c index a0ad9802b606..39b4d8a8107a 100644 --- a/drivers/spi/spi-qcom-qspi.c +++ b/drivers/spi/spi-qcom-qspi.c @@ -355,10 +355,22 @@ static int qcom_qspi_setup_dma_desc(struct qcom_qspi *ctrl, for (i = 0; i < sgt->nents; i++) { dma_ptr_sg = sg_dma_address(sgt->sgl + i); + dma_len_sg = sg_dma_len(sgt->sgl + i); if (!IS_ALIGNED(dma_ptr_sg, QSPI_ALIGN_REQ)) { dev_warn_once(ctrl->dev, "dma_address not aligned to %d\n", QSPI_ALIGN_REQ); return -EAGAIN; } + /* + * When reading with DMA the controller writes to memory 1 word + * at a time. If the length isn't a multiple of 4 bytes then + * the controller can clobber the things later in memory. + * Fallback to PIO to be safe. + */ + if (ctrl->xfer.dir == QSPI_READ && (dma_len_sg & 0x03)) { + dev_warn_once(ctrl->dev, "fallback to PIO for read of size %#010x\n", + dma_len_sg); + return -EAGAIN; + } } for (i = 0; i < sgt->nents; i++) {