Re: [ammarfaizi2-block:stable/linux-stable-rc/queue/5.4 15/15] kernel/bpf/core.c:1570:3: error: implicit declaration of function 'barrier_nospec'

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

On Thu, Feb 23, 2023 at 09:31:08PM +0800, kernel test robot wrote:
> tree:   https://github.com/ammarfaizi2/linux-block stable/linux-stable-rc/queue/5.4
> commit: 3bb990ea37595b41a1f06a551e5dd35372ea404a [15/15] uaccess: Add speculation barrier to copy_from_user()
...
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Link: https://lore.kernel.org/oe-kbuild-all/202302232136.AWzwjCvb-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
> >> kernel/bpf/core.c:1570:3: error: implicit declaration of function 'barrier_nospec' [-Werror,-Wimplicit-function-declaration]
>                    barrier_nospec();
>                    ^
>    1 error generated.

It's missing #include <linux/nospec.h>. The fix for this is:

Upstream f3dd0c53370e70c0f9b7e931bbec12916f3bb8cc ("bpf: add missing header file include")

That one needs to get backported too. Or just fold that in to maintain
the bisectability (for stable kernels).

Thanks,

-- 
Ammar Faizi