Subject: Re: [PATCH] bpf: Fix undeclared function 'barrier_nospec' warning
To:     Viresh Kumar <viresh.kumar@linaro.org>,
        Alexei Starovoitov <ast@kernel.org>,
        John Fastabend <john.fastabend@gmail.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Dave Hansen <dave.hansen@linux.intel.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org
References: <9c476aa64c9588205817833dbaa622f87c0e0081.1677051600.git.viresh.kumar@linaro.org>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <c1242eff-baf2-7f46-b7a7-667f973b04a7@iogearbox.net>
Date:   Wed, 22 Feb 2023 20:31:22 +0100
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On 2/22/23 9:24 AM, Viresh Kumar wrote:
> Add the missing header for architectures that don't define
> the barrier_nospec() macro. The nospec.h header is added after the
> inclusion of barrier.h to avoid redefining the macro for architectures
> that already define barrier_nospec() in their respective barrier.h
> headers.
> 
> Fixes: 74e19ef0ff80 ("uaccess: Add speculation barrier to copy_from_user()")
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> Linus's master branch fails currently to build for arm64 without this commit.
> 
>   kernel/bpf/core.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 933869983e2a..92aeb388e422 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -38,6 +38,8 @@
>   #include <linux/memcontrol.h>
>   
>   #include <asm/barrier.h>
> +#include <linux/nospec.h>
> +

nit: The asm/barrier.h include could have just been removed. linux/nospec.h
internally includes asm/barrier.h already.

>   #include <asm/unaligned.h>
>   
>   /* Registers */
>