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[92.34.200.121]) by smtp.gmail.com with ESMTPSA id j10sm610110lfc.43.2019.11.12.23.53.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Nov 2019 23:53:47 -0800 (PST) From: Linus Walleij To: Ulf Hansson , linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Stephan Gerhold Cc: Russell King , Linus Walleij , Ludovic Barre , Brian Masney , Niklas Cassel , Russell King Subject: [PATCH 3/3] mmc: mmci: Proper PIO residue handling Date: Wed, 13 Nov 2019 08:53:35 +0100 Message-Id: <20191113075335.31775-4-linus.walleij@linaro.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20191113075335.31775-1-linus.walleij@linaro.org> References: <20191113075335.31775-1-linus.walleij@linaro.org> MIME-Version: 1.0 Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org The MMCI PIO write function contains a bug if using any buffers with sglist miter contents that do not add upp to even 32bit writes. The PIO write code currently does this: iowrite32_rep(base + MMCIFIFO, ptr, (count + 3) >> 2); This will make sure that a single buffer passed in gets written into the FIFO even if it is odd, i.e. not evenly divisible by 4. However it has the following problems: - It will read up to three bytes beyond the end of the buffer and fill the FIFO with unpredictable junk and possibly cause segmentation violations if the read passes a page boundary such as at the end of an sglist buffer. - It will be fine if a single buffer is passed in, but the code handles SG lists. There is a while (1) loop in mmci_pio_irq() which repeatedly calls mmci_pio_write() as long as the FIFO is not half-full, if it gets half-full it exits the IRQ and waits for a new IRQ, also the while loop repeatedly calls sg_miter_next() to consume bytes and this means that between subsequent calls to mmci_pio_write() some random junk can be inserted at the end of each call if the buffers passed in do not contain an number of bytes evenly divisible by 4. Fix this by simply doing this: iowrite32_rep(base + MMCIFIFO, ptr, count >> 2); But since the code will then just not write enough bytes if the count is not evenly divisible by 4, we introduce a special residue buffer and keep track of any odd bytes from 1..3 and just write these padded out with new data in a separate statement the next time we get a call of the mmci_pio_write(), or, if there is for example only 1,2 or 3 bytes in the transfer, or we end up with an odd number of bytes in the residue, flushi it out when we end the current data transaction to the host. Cc: Ludovic Barre Cc: Brian Masney Cc: Stephan Gerhold Cc: Niklas Cassel Cc: Russell King Signed-off-by: Linus Walleij --- ChangeLog v1->v3: - New patch in v3 after discussion with Ulf - I'm unable to test this because I cannot provoke these odd reads/writes but hoping for Stephan to take it for a spin. --- drivers/mmc/host/mmci.c | 125 ++++++++++++++++++++++++++++++++++++---- drivers/mmc/host/mmci.h | 2 + 2 files changed, 117 insertions(+), 10 deletions(-) diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index a08cd845dddc..0d01689016f0 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -607,6 +607,7 @@ static void mmci_init_sg(struct mmci_host *host, struct mmc_data *data) flags |= SG_MITER_FROM_SG; sg_miter_start(&host->sg_miter, data->sg, data->sg_len, flags); + host->pio_write_residue_sz = 0; } static u32 mmci_get_dctrl_cfg(struct mmci_host *host) @@ -1422,30 +1423,111 @@ static int mmci_pio_write(struct mmci_host *host, char *buffer, unsigned int rem struct variant_data *variant = host->variant; void __iomem *base = host->base; char *ptr = buffer; + bool wrote_residue = false; + int i; + + /* + * This will normally not happen during block I/O, but can + * happen during SDIO traffic, where odd byte chunks are + * shoveled to the SDIO link. Fill up the residue buffer + * and flush out. + */ + if (host->pio_write_residue_sz) { + int fill = 4 - host->pio_write_residue_sz; + u32 val = 0; + + /* + * If we need more padding that what we have, just stash + * some more in the residue then and continue. This only + * happens if we're passed e.g. 1 or 2 bytes and there is + * just 1 byte residue residue already: we can't fill up! + */ + if (fill > remain) { + for (i = 0; i < fill; i++) { + host->pio_write_residue[host->pio_write_residue_sz + i] = *ptr; + host->pio_write_residue_sz++; + ptr++; + remain--; + } + return ptr - buffer; + } + + /* Pack the residue into a 32bit word */ + for (i = 0; i < host->pio_write_residue_sz; i++) { + val |= host->pio_write_residue[i]; + val <<= 8; + } + /* Top up with new data */ + for (i = 0; i < fill; i++) { + val |= *ptr; + val <<= 8; + ptr++; + remain--; + } + iowrite32(val, base + MMCIFIFO); + host->pio_write_residue_sz = 0; + wrote_residue = true; + } + + /* + * Maybe the residue plus some few bytes was exactly filling a + * 32bit word. + */ + if (!remain) + return ptr - buffer; do { - unsigned int count, maxcnt; + unsigned int count, maxcnt, written, residue; + /* + * If the FIFO is empty just stash it full with data else + * just half-fill it. + */ maxcnt = status & MCI_TXFIFOEMPTY ? - variant->fifosize : variant->fifohalfsize; + variant->fifosize : variant->fifohalfsize; + + /* Watch it to not overfill the FIFO */ + if (wrote_residue) + maxcnt -= 4; + count = min(remain, maxcnt); /* * SDIO especially may want to send something that is * not divisible by 4 (as opposed to card sectors - * etc), and the FIFO only accept full 32-bit writes. - * So compensate by adding +3 on the count, a single - * byte become a 32bit write, 7 bytes will be two - * 32bit writes etc. + * etc), but the FIFO only accepts full 32-bit writes so start by + * just filling up quickly with as much as we can. */ - iowrite32_rep(base + MMCIFIFO, ptr, (count + 3) >> 2); + iowrite32_rep(base + MMCIFIFO, ptr, count >> 2); + residue = count & 3; - ptr += count; - remain -= count; + written = count - residue; + ptr += written; + remain -= written; - if (remain == 0) + /* Handles the common case for block-IO */ + if (!remain) break; + /* + * These were not written out since we only write 32bit + * words to the FIFO. Since this function gets called + * repeatedly and across page boundaries with new pointers + * in *buffer we need to take special care to stash odd + * bytes away and flush them out in next PIO round or at the + * end of the whole data transfer. + */ + if (remain < 4) { + WARN_ON(remain != residue); + host->pio_write_residue_sz = residue; + for (i = 0; i < residue; i++) { + host->pio_write_residue[i] = *ptr; + ptr++; + remain--; + } + break; + } + status = readl(base + MMCISTATUS); } while (status & MCI_TXFIFOHALFEMPTY); @@ -1522,6 +1604,29 @@ static irqreturn_t mmci_pio_irq(int irq, void *dev_id) if (host->size == 0) { mmci_set_mask1(host, 0); writel(readl(base + MMCIMASK0) | MCI_DATAENDMASK, base + MMCIMASK0); + + if ((status & MCI_TXACTIVE) && host->pio_write_residue_sz) { + /* + * If the last pass of the SG miter left some residue after the pio + * write loop, push that out to the card. We are now at the end of + * the transfer so it is OK to pad with zeroes. + */ + int fill = 4 - host->pio_write_residue_sz; + u32 val = 0; + int i; + + /* Pack the residue into a 32bit word */ + for (i = 0; i < host->pio_write_residue_sz; i++) { + val |= host->pio_write_residue[i]; + val <<= 8; + } + /* Top up with zeroes */ + for (i = 0; i < fill; i++) + val <<= 8; + + iowrite32(val, base + MMCIFIFO); + host->pio_write_residue_sz = 0; + } } return IRQ_HANDLED; diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h index e20af17bb313..a7690b64d4cd 100644 --- a/drivers/mmc/host/mmci.h +++ b/drivers/mmc/host/mmci.h @@ -425,6 +425,8 @@ struct mmci_host { /* pio stuff */ struct sg_mapping_iter sg_miter; unsigned int size; + u8 pio_write_residue[4]; + u8 pio_write_residue_sz; int (*get_rx_fifocnt)(struct mmci_host *h, u32 status, int remain); u8 use_dma:1;