[v6,2/2] usb/gadget: Add driver for Aspeed SoC virtual hub

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Sun, 2018-03-25 at 12:25 +1100, Benjamin Herrenschmidt wrote:
> On Sat, 2018-03-24 at 12:19 +1100, Benjamin Herrenschmidt wrote:
> > > In function ‘memcpy’,
> > >      inlined from ‘ast_vhub_rep_desc’ at drivers/usb/gadget/udc/aspeed-vhub/hub.c:276:2:
> > > ./include/linux/string.h:341:4: error: call to ‘__read_overflow2’ declared with attribute error: detected read beyond size of object passed as 2nd parameter
> > >      __read_overflow2();
> > 
> > That's really odd... some new gcc thing ? I don't understand where the
> > overflow would occur... Do you see anything ? Unless my brain is acting
> > up, there is no overflow and gcc is bogus:
> > 
> > I just hand counted the size of the 3 possible structures "desc" can
> > point to and compared to the constants used for the size, and it all
> > fits.
> > 
> > Unfortunately, I can't seem to reproduce with the version of cross
> > compiler I'm using here, so I'm not sure what construct to use to
> > make gcc stop erroneously barfing...
> 
> So I've tried with 2 ARM cross compilers (gcc 6.3.0 built by buildroot
> and 7.2.1 from Fedora 27) and couldn't reproduce this.
> 
> I also tried an x86_64 build with that driver with 7.3.1 20180130 (from
> Fedora 27) and here too, couldn't reproduce the problem.
> 
> What toolchain precisely are you using ? It really smells like a gcc
> bug to me...

Today Joel tried on a 7.3.0 from Ubuntu, still no error. We tried a
gcc 8, and while we didn't hit that error, it did spew a couple
of warnings, one of them being an actual typo/bug so I'll send a
v7 today, however, nothing like what you reported.

Cheers,
Ben.
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