Hi Boris,
On 2/23/20 4:02 AM, Boris ARZUR wrote:
Hi Guenter,
I tried your series of patch. rndis_host tethering & loading the machine
seems to work fine. No more crashing.
That being said, I now have an issue with regular USB keys (I tried a few):
usb 3-1: reset high-speed USB device number 2 using dwc2
I was able to reproduce this issue with the unpatched kernel, by disabling
the early return in dwc2_alloc_dma_aligned_buffer(), see attached.
There are times were re-allocation fails, either with your patch or with
the (almost-)original code.
In particular it seems that there is a packet of lenght 13, usb_urb_dir_in() == true,
usb_pipetype(urb->pipe) == PIPE_BULK, that comes in every 2s or so, that
does not reallocate properly.
In the original code, it's not a problem thanks to the early return, but your code
wants 512B (maxp) and forces reallocation...
Thanks for finding this. Back to the drawing board.
Thanks, Boris.
Guenter Roeck wrote:
On Sat, Feb 15, 2020 at 02:36:47PM +0900, Boris ARZUR wrote:
Hi Guenter,
The first time around I was 0/ changing fonts 1/ trimming the dump message
in the kernel 2/ filming my screen. That's not practical at all...
Mmm, pstore does seem to work on my machine. CHROME_PSTORE is not available
to me because I'm not on x86, I just enabled the rest and nothing pops up
Your system is Veyron, isn't it ? It does support pstore (I am using one for
my testing as well), but I guess that depends on the BIOS/firmware installed.
Guenter
in /sys/fs/pstore...
So I took pictures (OCR did not help):
- https://funyu.konbu.org/pQUF2P08etcpVxuKZ0A720%2b0/IMG_20200215_134343.jpg.webp
is a stack trace for your earlier patch "min_t", in
https://www.spinics.net/lists/linux-usb/msg191019.html ;
- https://funyu.konbu.org/pQUF2P08etcpVxuKZ0A720%2b0/IMG_20200215_135816.jpg.webp
is a stack trace for your later patch "container_of", in
https://www.spinics.net/lists/linux-usb/msg191074.html .
Both patches crash (without even loading the machine), but "container_of" is
a bit more resilient.
Yes, those patches didn't address the core problem. Can you test with the
attached two patches ?
Thanks,
Guenter
From a1c0551b62b038b495177737828f986961184110 Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@xxxxxxxxxxxx>
Date: Mon, 10 Feb 2020 14:04:06 -0800
Subject: [PATCH 1/2] usb: dwc2: Simplify DMA alignment code
The code to align buffers for DMA was first introduced with commit
3bc04e28a030 ("usb: dwc2: host: Get aligned DMA in a more supported way").
It was updated with commit 56406e017a88 ("usb: dwc2: Fix DMA alignment
to start at allocated boundary") because it did not really align buffers to
DMA boundaries but to DWC2_USB_DMA_ALIGN. This was then optimized in commit
1e111e885238 ("usb: dwc2: Fix inefficient copy of unaligned buffers")
to only copy actual data rather than the whole buffer. Commit 4a4863bf2e79
("usb: dwc2: Fix DMA cache alignment issues") changed this further to add
a padding at the end of the buffer to ensure that the old data pointer is
not in the same cache line as the buffer.
This last commit states "Otherwise, the stored_xfer_buffer gets corrupted
for IN URBs on non-cache-coherent systems". However, such corruptions are
still observed. Either case, DMA is not expected to overwrite more memory
than it is supposed to do, suggesting that the commit may have been hiding
a problem rather than fixing it.
On top of that, DMA alignment is still not guaranteed since it only happens
if the original buffer is not aligned to DWC2_USB_DMA_ALIGN, which is still
a constant of 4 and not really associated with DMA alignment.
Move the old data pointer back to the beginning of the new buffer,
restoring most of the original commit and to simplify the code. Define
DWC2_USB_DMA_ALIGN to dma_get_cache_alignment() to fix the DMA alignment
for real this time.
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
drivers/usb/dwc2/hcd.c | 50 +++++++++++++++++++-----------------------
1 file changed, 22 insertions(+), 28 deletions(-)
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index b90f858af960..b5841197165a 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -2469,21 +2469,24 @@ static int dwc2_alloc_split_dma_aligned_buf(struct dwc2_hsotg *hsotg,
return 0;
}
-#define DWC2_USB_DMA_ALIGN 4
+#define DWC2_USB_DMA_ALIGN dma_get_cache_alignment()
+
+struct dma_aligned_buffer {
+ void *kmalloc_ptr;
+ void *old_xfer_buffer;
+ u8 data[0];
+};
static void dwc2_free_dma_aligned_buffer(struct urb *urb)
{
- void *stored_xfer_buffer;
+ struct dma_aligned_buffer *temp;
size_t length;
if (!(urb->transfer_flags & URB_ALIGNED_TEMP_BUFFER))
return;
- /* Restore urb->transfer_buffer from the end of the allocated area */
- memcpy(&stored_xfer_buffer,
- PTR_ALIGN(urb->transfer_buffer + urb->transfer_buffer_length,
- dma_get_cache_alignment()),
- sizeof(urb->transfer_buffer));
+ temp = container_of(urb->transfer_buffer,
+ struct dma_aligned_buffer, data);
if (usb_urb_dir_in(urb)) {
if (usb_pipeisoc(urb->pipe))
@@ -2491,17 +2494,17 @@ static void dwc2_free_dma_aligned_buffer(struct urb *urb)
else
length = urb->actual_length;
- memcpy(stored_xfer_buffer, urb->transfer_buffer, length);
+ memcpy(temp->old_xfer_buffer, temp->data, length);
}
- kfree(urb->transfer_buffer);
- urb->transfer_buffer = stored_xfer_buffer;
+ urb->transfer_buffer = temp->old_xfer_buffer;
+ kfree(temp->kmalloc_ptr);
urb->transfer_flags &= ~URB_ALIGNED_TEMP_BUFFER;
}
static int dwc2_alloc_dma_aligned_buffer(struct urb *urb, gfp_t mem_flags)
{
- void *kmalloc_ptr;
+ struct dma_aligned_buffer *temp, *kmalloc_ptr;
size_t kmalloc_size;
if (urb->num_sgs || urb->sg ||
@@ -2509,31 +2512,22 @@ static int dwc2_alloc_dma_aligned_buffer(struct urb *urb, gfp_t mem_flags)
!((uintptr_t)urb->transfer_buffer & (DWC2_USB_DMA_ALIGN - 1)))
return 0;
- /*
- * Allocate a buffer with enough padding for original transfer_buffer
- * pointer. This allocation is guaranteed to be aligned properly for
- * DMA
- */
+ /* Allocate a buffer with enough padding for alignment */
kmalloc_size = urb->transfer_buffer_length +
- (dma_get_cache_alignment() - 1) +
- sizeof(urb->transfer_buffer);
+ sizeof(struct dma_aligned_buffer) + DWC2_USB_DMA_ALIGN - 1;
kmalloc_ptr = kmalloc(kmalloc_size, mem_flags);
if (!kmalloc_ptr)
return -ENOMEM;
- /*
- * Position value of original urb->transfer_buffer pointer to the end
- * of allocation for later referencing
- */
- memcpy(PTR_ALIGN(kmalloc_ptr + urb->transfer_buffer_length,
- dma_get_cache_alignment()),
- &urb->transfer_buffer, sizeof(urb->transfer_buffer));
-
+ /* Position our struct dma_aligned_buffer such that data is aligned */
+ temp = PTR_ALIGN(kmalloc_ptr + 1, DWC2_USB_DMA_ALIGN) - 1;
+ temp->kmalloc_ptr = kmalloc_ptr;
+ temp->old_xfer_buffer = urb->transfer_buffer;
if (usb_urb_dir_out(urb))
- memcpy(kmalloc_ptr, urb->transfer_buffer,
+ memcpy(temp->data, urb->transfer_buffer,
urb->transfer_buffer_length);
- urb->transfer_buffer = kmalloc_ptr;
+ urb->transfer_buffer = temp->data;
urb->transfer_flags |= URB_ALIGNED_TEMP_BUFFER;
--
2.17.1
From 9df13854b3717f8c16a2012dec614f737bb8c15d Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@xxxxxxxxxxxx>
Date: Mon, 10 Feb 2020 13:11:00 -0800
Subject: [PATCH 2/2] usb: dwc2: Allocate input buffers as multiples of
wMaxPacketSize
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
The following messages are seen on Veyron Chromebooks running v4.19 or
later kernels.
dwc2 ff580000.usb: dwc2_update_urb_state(): trimming xfer length
dwc2 ff580000.usb: dwc2_hc_chhltd_intr_dma: Channel 7 - ChHltd set, but reason is unknown
dwc2 ff580000.usb: hcint 0x00000002, intsts 0x04600021
This is typically followed by a crash.
Unable to handle kernel paging request at virtual address 29f9d9fc
pgd = 4797dac9
[29f9d9fc] *pgd=80000000004003, *pmd=00000000
Internal error: Oops: a06 [#1] PREEMPT SMP ARM
Modules linked in: ip6t_REJECT rfcomm i2c_dev uinput hci_uart btbcm ...
CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 4.19.87-07825-g4ab3515f6e4d #1
Hardware name: Rockchip (Device Tree)
PC is at memcpy+0x50/0x330
LR is at 0xdd9ac94
...
[<c0a89f50>] (memcpy) from [<c0783b94>] (dwc2_free_dma_aligned_buffer+0x5c/0x7c)
[<c0783b94>] (dwc2_free_dma_aligned_buffer) from [<c0765dcc>] (__usb_hcd_giveback_urb+0x78/0x130)
[<c0765dcc>] (__usb_hcd_giveback_urb) from [<c07678fc>] (usb_giveback_urb_bh+0xa0/0xe4)
[<c07678fc>] (usb_giveback_urb_bh) from [<c023a164>] (tasklet_action_common+0xc0/0xdc)
[<c023a164>] (tasklet_action_common) from [<c02021f0>] (__do_softirq+0x1b8/0x434)
[<c02021f0>] (__do_softirq) from [<c0239a14>] (irq_exit+0xdc/0xe0)
[<c0239a14>] (irq_exit) from [<c029f260>] (__handle_domain_irq+0x94/0xd0)
[<c029f260>] (__handle_domain_irq) from [<c05da780>] (gic_handle_irq+0x74/0xb0)
[<c05da780>] (gic_handle_irq) from [<c02019f8>] (__irq_svc+0x58/0x8c)
The crash suggests that the memory after the end of a temporary DMA-aligned
buffer is overwritten.
The problem is typically only seen in kernels which include commit
56406e017a88 ("usb: dwc2: Fix DMA alignment to start at allocated
boundary"), presumably because that commit moves the pointer to the old
buffer to the end of the newly allocated buffer, where it is more likely
to be overwritten.
Code analysis shows that the transfer size programmed into the chip for
input transfers is a multiple of an endpoint's maximum packet size
(wMaxPacketSize). In the observed situation, the transfer size and thus
the size of the input buffer is 1522 bytes. With a maximum packet size
of 64 bytes, the chip is programmed to receive up to 1536 bytes of data.
This overwrites the end of the buffer.
To work around the problem, always allocate a multiple of wMaxPacketSize
bytes for receive buffers. Do this even for DMA-aligned buffers if the
receive buffer size is not a multiple of wMaxPacketSize. At the same time,
do not update chan->xfer_len if the transfer size is 0.
Reported-by: Boris ARZUR <boris@xxxxxxxxx>
Cc: Boris ARZUR <boris@xxxxxxxxx>
Cc: Jonathan Bell <jonathan@xxxxxxxxxxxxxxx>
Cc: Antti Seppälä <a.seppala@xxxxxxxxx>
Fixes: 56406e017a88 ("usb: dwc2: Fix DMA alignment to start at allocated boundary")
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
drivers/usb/dwc2/hcd.c | 37 +++++++++++++++++++++++++++----------
1 file changed, 27 insertions(+), 10 deletions(-)
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index b5841197165a..f27dc11e409c 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -1313,18 +1313,20 @@ static void dwc2_hc_start_transfer(struct dwc2_hsotg *hsotg,
if (num_packets > max_hc_pkt_count) {
num_packets = max_hc_pkt_count;
chan->xfer_len = num_packets * chan->max_packet;
+ } else if (chan->ep_is_in) {
+ /*
+ * Always program an integral # of max packets for IN
+ * transfers.
+ * Note: This assumes that the input buffer is
+ * aligned accordingly.
+ */
+ chan->xfer_len = num_packets * chan->max_packet;
}
} else {
/* Need 1 packet for transfer length of 0 */
num_packets = 1;
}
- if (chan->ep_is_in)
- /*
- * Always program an integral # of max packets for IN
- * transfers
- */
- chan->xfer_len = num_packets * chan->max_packet;
if (chan->ep_type == USB_ENDPOINT_XFER_INT ||
chan->ep_type == USB_ENDPOINT_XFER_ISOC)
@@ -2505,16 +2507,31 @@ static void dwc2_free_dma_aligned_buffer(struct urb *urb)
static int dwc2_alloc_dma_aligned_buffer(struct urb *urb, gfp_t mem_flags)
{
struct dma_aligned_buffer *temp, *kmalloc_ptr;
+ struct usb_host_endpoint *ep = urb->ep;
+ int maxp = usb_endpoint_maxp(&ep->desc);
size_t kmalloc_size;
- if (urb->num_sgs || urb->sg ||
- urb->transfer_buffer_length == 0 ||
+ if (urb->num_sgs || urb->sg || urb->transfer_buffer_length == 0)
+ return 0;
+
+ /*
+ * Input transfer buffer size must be a multiple of the endpoint's
+ * maximum packet size to match the transfer limit programmed into
+ * the chip.
+ * See calculation of chan->xfer_len in dwc2_hc_start_transfer().
+ */
+ if (usb_urb_dir_out(urb))
+ kmalloc_size = urb->transfer_buffer_length;
+ else
+ kmalloc_size = roundup(urb->transfer_buffer_length, maxp);
+
+ if (kmalloc_size == urb->transfer_buffer_length &&
!((uintptr_t)urb->transfer_buffer & (DWC2_USB_DMA_ALIGN - 1)))
return 0;
/* Allocate a buffer with enough padding for alignment */
- kmalloc_size = urb->transfer_buffer_length +
- sizeof(struct dma_aligned_buffer) + DWC2_USB_DMA_ALIGN - 1;
+ kmalloc_size += sizeof(struct dma_aligned_buffer) +
+ DWC2_USB_DMA_ALIGN - 1;
kmalloc_ptr = kmalloc(kmalloc_size, mem_flags);
if (!kmalloc_ptr)
--
2.17.1
