On 17.11.2017 16:04, Marek Vasut wrote:
On 11/17/2017 03:28 PM, Dirk Behme wrote:
Its a valid use case to call ehci_submit_async() with a NULL buffer
with length 0. E.g. from usb_set_configuration().
As invalidate_dcache_range() isn't able to judge if the address
NULL is valid or not (depending on the SoC hardware configuration it
might be valid) do the check in ehci_submit_async() as here we know
that we don't have to invalidate such a buffer.
Signed-off-by: Dirk Behme <dirk.be...@de.bosch.com>
Looks OK,
Ok, thanks, I'll drop the RFC, then.
what about the other cache ops in EHCI, are they also affected?
This was found based on a MMU configuration excluding address
0x00000000. Fixing this one location made a usb start and reading from
an USB stick work.
So either only this location is affected, or above use case doesn't
cover all relevant path. In latter case I don't have enough USB
knowledge to evaluate all path by review.
Best regards
Dirk
---
Notes:
This was found on an older vendor specific U-Boot on an ARMv8 SoC
with a MMU configuration where address 0x00000000 is invalid.
The callstack I've seen is
usb_set_configuration(), calls
-> usb_control_msg() with *data == NULL and size == 0
-> submit_control_msg()
-> _ehci_submit_control_msg()
-> ehci_submit_async()
ehci_submit_async() called __asm_invalidate_dcache_range() from
arch/arm/cpu/armv8/cache.S, then. Resulting in an exception trying
to use address 0 in x0 (dc ivac, x0).
I'm slightly unsure why this hasn't been catched or complained about
previously, already. Maybe I missed anything while working with an older
vendor U-Boot? Sorry in this case.
Best regards
Dirk
---
drivers/usb/host/ehci-hcd.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index be3e842dcc..32c661b37e 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -595,8 +595,9 @@ ehci_submit_async(struct usb_device *dev, unsigned long
pipe, void *buffer,
* dangerous operation, it's responsibility of the calling
* code to make sure enough space is reserved.
*/
- invalidate_dcache_range((unsigned long)buffer,
- ALIGN((unsigned long)buffer + length, ARCH_DMA_MINALIGN));
+ if (buffer != NULL && length > 0)
+ invalidate_dcache_range((unsigned long)buffer,
+ ALIGN((unsigned long)buffer + length,
ARCH_DMA_MINALIGN));
/* Check that the TD processing happened */
if (QT_TOKEN_GET_STATUS(token) & QT_TOKEN_STATUS_ACTIVE)
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