usb/gadget: Add driver for Aspeed SoC virtual hub

Quoted 9 lines · Benjamin Herrenschmidt

Quoted 4 lines

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:

Quoted 7 lines

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...