netdev - Re: [PATCH net-next] bpf: fix pointer cast warning

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Date:   Wed, 21 Jul 2021 14:45:42 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Florent Revest <revest@...omium.org>,
        Alan Maguire <alan.maguire@...cle.com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] bpf: fix pointer cast warning

On Wed, Jul 21, 2021 at 2:20 PM Arnd Bergmann <arnd@...nel.org> wrote:
>
> From: Arnd Bergmann <arnd@...db.de>
>
> kp->addr is a pointer, so it cannot be cast directly to a 'u64'
> when it gets interpreted as an integer value:
>
> kernel/trace/bpf_trace.c: In function '____bpf_get_func_ip_kprobe':
> kernel/trace/bpf_trace.c:968:21: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
>   968 |         return kp ? (u64) kp->addr : 0;
>
> Use the uintptr_t type instead.
>
> Fixes: 9ffd9f3ff719 ("bpf: Add bpf_get_func_ip helper for kprobe programs")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---

I'll take this through the bpf-next tree, if no one objects. Thanks for the fix!


>  kernel/trace/bpf_trace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 0de09f068697..a428d1ef0085 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -965,7 +965,7 @@ BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
>  {
>         struct kprobe *kp = kprobe_running();
>
> -       return kp ? (u64) kp->addr : 0;
> +       return kp ? (uintptr_t)kp->addr : 0;
>  }
>
>  static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
> --
> 2.29.2
>