Re: linux-next: Tree for Jan 12 (build failures: m68k, ppc)

On 01/15/2015 02:12 AM, Geert Uytterhoeven wrote:

On Mon, Jan 12, 2015 at 6:59 PM, Guenter Roeck [off-list ref] wrote:

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Build failures, seen since next-20150109:
         m68k:allmodconfig
         powerpc:ppc6xx_defconfig

It looks like parisc is also suffering:
http://kisskb.ellerman.id.au/kisskb/buildresult/12343847/

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Due to:
         ERROR: "__get_user_bad" [drivers/gpu/drm/drm.ko] undefined!
         make[1]: *** [__modpost] Error 1

Caused by commit d34f20d6e2f (drm: Atomic modeset ioctl).

Yeah, it needs a get_user() that supports 64-bit data.

Hi Geert,

I assume you mean m68k, where 64 bit support for get_user has been disabled.

The problem on powerpc is different though: __get_user_nocheck()
and __get_user_check() use
         unsigned long __gu_val;
followed by
         __get_user_size(__gu_val, __gu_addr, (size), __gu_err);

__get_user_size() fails in
         if (size > sizeof(x))
                  (x) = __get_user_bad();

Presumably "unsigned long" is 32 bit on 32 bit powerpc, not 64 bit.

Overall, the explicit 64-bit use of get_user() seems to be quite unusual.

I noticed you've sent a fix for DRM.

Doh, and I was just fixing m68k...

Sorry, should have Cc:'d you.

Guenter