linux-kernel - [PATCH V2 4/4] mic: vop: copy data to kernel space then write to io memory

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Message-Id: <20200929091106.24624-5-sherry.sun@nxp.com>
Date:   Tue, 29 Sep 2020 17:11:06 +0800
From:   Sherry Sun <sherry.sun@....com>
To:     sudeep.dutt@...el.com, ashutosh.dixit@...el.com, arnd@...db.de,
        gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, linux-imx@....com
Subject: [PATCH V2 4/4] mic: vop: copy data to kernel space then write to io memory

Read and write io memory should address align on ARCH ARM. Change to use
memcpy_toio to avoid kernel panic caused by the address un-align issue.

Signed-off-by: Sherry Sun <sherry.sun@....com>
Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
---
 drivers/misc/mic/vop/vop_vringh.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/misc/mic/vop/vop_vringh.c b/drivers/misc/mic/vop/vop_vringh.c
index 45fdb394de11..7014ffe88632 100644
--- a/drivers/misc/mic/vop/vop_vringh.c
+++ b/drivers/misc/mic/vop/vop_vringh.c
@@ -602,6 +602,7 @@ static int vop_virtio_copy_from_user(struct vop_vdev *vdev, void __user *ubuf,
 	size_t partlen;
 	bool dma = VOP_USE_DMA && vi->dma_ch;
 	int err = 0;
+	size_t offset = 0;
 
 	if (dma) {
 		dma_alignment = 1 << vi->dma_ch->device->copy_align;
@@ -655,13 +656,20 @@ static int vop_virtio_copy_from_user(struct vop_vdev *vdev, void __user *ubuf,
 	 * We are copying to IO below and should ideally use something
 	 * like copy_from_user_toio(..) if it existed.
 	 */
-	if (copy_from_user((void __force *)dbuf, ubuf, len)) {
-		err = -EFAULT;
-		dev_err(vop_dev(vdev), "%s %d err %d\n",
-			__func__, __LINE__, err);
-		goto err;
+	while (len) {
+		partlen = min_t(size_t, len, VOP_INT_DMA_BUF_SIZE);
+
+		if (copy_from_user(vvr->buf, ubuf + offset, partlen)) {
+			err = -EFAULT;
+			dev_err(vop_dev(vdev), "%s %d err %d\n",
+				__func__, __LINE__, err);
+			goto err;
+		}
+		memcpy_toio(dbuf + offset, vvr->buf, partlen);
+		offset += partlen;
+		vdev->out_bytes += partlen;
+		len -= partlen;
 	}
-	vdev->out_bytes += len;
 	err = 0;
 err:
 	vpdev->hw_ops->unmap(vpdev, dbuf);
-- 
2.17.1