Re: [Qemu-devel] [PATCH] Bug Fix:Segmentation fault when use usb-ehci device

[Mike Qiu <qiudayu@linux.vnet.ibm.com>]

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于 2013/7/19 1:14, Andreas Färber 写道:
> Hi,
>
> Am 18.07.2013 17:27, schrieb Mike Qiu:
>> Hi all
>>
>> Any comments ?
> You should've CCed the USB maintainer whose file you are touching for
> review rather than just ppc people, see ./MAINTAINERS.
I have CC to the usb naintainer Gerd Hoffmann, his files are hw/usb/*.

>
> There's some typos in the commit message, but the change looks okay to
> me - although there were discussions to catch this on the memory API
> side of things instead.
You mean this patch: see below:

exec: Support 64-bit operations in address_s

if so it is very different.

BTW, this bug has been opened before?

Thanks
Mike
>
> Regards,
> Andreas
>
>> Thanks
>> Mike
>> 2013/7/16 11:50, Mike Qiu wrote:
>>> For usb-ehci in qemu, its caps just has read() operation,
>>> the write() operation does not exist.
>>>
>>> This cause a Segmentation fault when use usb-ehci device in ppc64
>>> platform.
>>>
>>> here is gdb output:
>>>
>>> Program received signal SIGSEGV, Segmentation fault.
>>> [Switching to Thread 0x3fffa7fcef20 (LWP 6793)]
>>> 0x00000000103f5244 in memory_region_oldmmio_write_accessor
>>> (opaque=0x113e9e78, addr=9, value=0x3fffa7fce088,
>>> size=1, shift=0, mask=255) at /home/Mike/qemu-impreza/memory.c:384
>>> 384  mr->ops->old_mmio.write[ctz32(size)](mr->opaque, addr, tmp);
>>> (gdb) p *mr->ops
>>> $1 = {read = @0x10716f68: 0x1020699c <ehci_caps_read>, write = 0,
>>>     endianness = DEVICE_LITTLE_ENDIAN, valid = {min_access_size = 1,
>>>     max_access_size = 4, unaligned = false, accepts = 0}, impl =
>>>     {min_access_size = 1, max_access_size = 1, unaligned = false},
>>>     old_mmio = {read = {0, 0, 0}, write = {0, 0, 0}}}
>>>
>>> Becasue function write() of mr->ops has not been implement, in
>>> function memory_region_dispatch_write(), it call
>>> oldmmio write accessor, but at the same time old_mmio still not
>>> been implement by default.
>>>
>>> That is the root cause of the Segmentation fault.
>>>
>>> To solve this problem, add empty function: ehci_caps_write()
>>>
>>> Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
>>> ---
>>>   hw/usb/hcd-ehci.c |    7 +++++++
>>>   1 file changed, 7 insertions(+)
>>>
>>> diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
>>> index 67e4b24..6c8a439 100644
>>> --- a/hw/usb/hcd-ehci.c
>>> +++ b/hw/usb/hcd-ehci.c
>>> @@ -1072,6 +1072,12 @@ static void ehci_port_write(void *ptr, hwaddr addr,
>>>       trace_usb_ehci_portsc_change(addr + s->portscbase, addr >> 2, *portsc, old);
>>>   }
>>>
>>> +static void ehci_caps_write(void *ptr, hwaddr addr, uint64_t val,
>>> +                           unsigned size)
>>> +{
>>> +    /* nothing */
>>> +}
>>> +
>>>   static void ehci_opreg_write(void *ptr, hwaddr addr,
>>>                                uint64_t val, unsigned size)
>>>   {
>>> @@ -2380,6 +2386,7 @@ static void ehci_frame_timer(void *opaque)
>>>
>>>   static const MemoryRegionOps ehci_mmio_caps_ops = {
>>>       .read = ehci_caps_read,
>>> +    .write = ehci_caps_write,
>>>       .valid.min_access_size = 1,
>>>       .valid.max_access_size = 4,
>>>       .impl.min_access_size = 1,
>>
>


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