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

On Mon, Jan 12, 2015 at 05:27:08PM +0100, Geert Uytterhoeven wrote:

On Mon, Jan 12, 2015 at 5:24 PM, Guenter Roeck [off-list ref] wrote:

quoted

On Mon, Jan 12, 2015 at 06:03:22PM +1100, Stephen Rothwell wrote:

quoted

Hi all,

Changes since 20150109:

The usb-gadget-fixes tree gained a conflict against the usb.current tree.

The net-next tree gained a build failure for which I reverted a commit.

The pinctrl tree gained a build failure so I used the version from
next-20150109.

The akpm tree lost a few patches that turned up elsewhere.

Non-merge commits (relative to Linus' tree): 2202
 2272 files changed, 69868 insertions(+), 38441 deletions(-)

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

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.

Thanks,
Guenter