linux-kernel - [PATCH 4.14 43/53] usb: dwc2: Fix DMA cache alignment issues

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Message-Id: <20190617210752.152355123@linuxfoundation.org>
Date:   Mon, 17 Jun 2019 23:10:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Douglas Anderson <dianders@...omium.org>,
        Minas Harutyunyan <hminas@...opsys.com>,
        Martin Schiller <ms@....tdt.de>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>
Subject: [PATCH 4.14 43/53] usb: dwc2: Fix DMA cache alignment issues

From: Martin Schiller <ms@....tdt.de>

commit 4a4863bf2e7932e584a3a462d3c6daf891142ddc upstream.

Insert a padding between data and the stored_xfer_buffer pointer to
ensure they are not on the same cache line.

Otherwise, the stored_xfer_buffer gets corrupted for IN URBs on
non-cache-coherent systems. (In my case: Lantiq xRX200 MIPS)

Fixes: 3bc04e28a030 ("usb: dwc2: host: Get aligned DMA in a more supported way")
Fixes: 56406e017a88 ("usb: dwc2: Fix DMA alignment to start at allocated boundary")
Cc: <stable@...r.kernel.org>
Tested-by: Douglas Anderson <dianders@...omium.org>
Reviewed-by: Douglas Anderson <dianders@...omium.org>
Acked-by: Minas Harutyunyan <hminas@...opsys.com>
Signed-off-by: Martin Schiller <ms@....tdt.de>
Signed-off-by: Felipe Balbi <felipe.balbi@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/dwc2/hcd.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -2652,8 +2652,10 @@ static void dwc2_free_dma_aligned_buffer
 		return;
 
 	/* Restore urb->transfer_buffer from the end of the allocated area */
-	memcpy(&stored_xfer_buffer, urb->transfer_buffer +
-	       urb->transfer_buffer_length, sizeof(urb->transfer_buffer));
+	memcpy(&stored_xfer_buffer,
+	       PTR_ALIGN(urb->transfer_buffer + urb->transfer_buffer_length,
+			 dma_get_cache_alignment()),
+	       sizeof(urb->transfer_buffer));
 
 	if (usb_urb_dir_in(urb))
 		memcpy(stored_xfer_buffer, urb->transfer_buffer,
@@ -2680,6 +2682,7 @@ static int dwc2_alloc_dma_aligned_buffer
 	 * DMA
 	 */
 	kmalloc_size = urb->transfer_buffer_length +
+		(dma_get_cache_alignment() - 1) +
 		sizeof(urb->transfer_buffer);
 
 	kmalloc_ptr = kmalloc(kmalloc_size, mem_flags);
@@ -2690,7 +2693,8 @@ static int dwc2_alloc_dma_aligned_buffer
 	 * Position value of original urb->transfer_buffer pointer to the end
 	 * of allocation for later referencing
 	 */
-	memcpy(kmalloc_ptr + urb->transfer_buffer_length,
+	memcpy(PTR_ALIGN(kmalloc_ptr + urb->transfer_buffer_length,
+			 dma_get_cache_alignment()),
 	       &urb->transfer_buffer, sizeof(urb->transfer_buffer));
 
 	if (usb_urb_dir_out(urb))