From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Arnd Bergmann" <arnd@arndb.de>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Andrii Nakryiko" <andrii@kernel.org>,
"John Fastabend" <john.fastabend@gmail.com>,
"KP Singh" <kpsingh@chromium.org>,
"David Miller" <davem@davemloft.net>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Jakub Sitnicki" <jakub@cloudflare.com>,
"Björn Töpel" <bjorn.topel@intel.com>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
"Jiri Olsa" <jolsa@kernel.org>,
"Pankaj Bharadiya" <pankaj.laxminarayan.bharadiya@intel.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
"open list" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] bpf: suppress -Wcast-function-type warning
Date: Mon, 26 Oct 2020 15:26:11 -0700 [thread overview]
Message-ID: <CAEf4BzaKSzEbPStm8EXk4RH417jHieSF3LCazQPXZ6qGskqB6Q@mail.gmail.com> (raw)
In-Reply-To: <20201026210332.3885166-1-arnd@kernel.org>
On Mon, Oct 26, 2020 at 2:03 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> Building with -Wextra shows lots of warnings in the bpf
> code such as
>
> kernel/bpf/verifier.c: In function ‘jit_subprogs’:
> include/linux/filter.h:345:4: warning: cast between incompatible function types from ‘unsigned int (*)(const void *, const struct bpf_insn *)’ to ‘u64 (*)(u64, u64, u64, u64, u64)’ {aka ‘long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)’} [-Wcast-function-type]
> 345 | ((u64 (*)(u64, u64, u64, u64, u64))(x))
> | ^
> kernel/bpf/verifier.c:10706:16: note: in expansion of macro ‘BPF_CAST_CALL’
> 10706 | insn->imm = BPF_CAST_CALL(func[subprog]->bpf_func) -
> | ^~~~~~~~~~~~~
>
> This appears to be intentional, so change the cast in a way that
> suppresses the warning.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
LGTM.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
> include/linux/filter.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/filter.h b/include/linux/filter.h
> index 1b62397bd124..20ba04583eaa 100644
> --- a/include/linux/filter.h
> +++ b/include/linux/filter.h
> @@ -342,7 +342,7 @@ static inline bool insn_is_zext(const struct bpf_insn *insn)
> /* Function call */
>
> #define BPF_CAST_CALL(x) \
> - ((u64 (*)(u64, u64, u64, u64, u64))(x))
> + ((u64 (*)(u64, u64, u64, u64, u64))(uintptr_t)(x))
>
> #define BPF_EMIT_CALL(FUNC) \
> ((struct bpf_insn) { \
> --
> 2.27.0
>
prev parent reply other threads:[~2020-10-26 22:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 21:03 [PATCH] bpf: suppress -Wcast-function-type warning Arnd Bergmann
2020-10-26 22:20 ` David Laight
2020-10-26 22:26 ` Andrii Nakryiko [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAEf4BzaKSzEbPStm8EXk4RH417jHieSF3LCazQPXZ6qGskqB6Q@mail.gmail.com \
--to=andrii.nakryiko@gmail.com \
--cc=andrii@kernel.org \
--cc=arnd@arndb.de \
--cc=arnd@kernel.org \
--cc=ast@kernel.org \
--cc=bjorn.topel@intel.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=jakub@cloudflare.com \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kafai@fb.com \
--cc=kpsingh@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pankaj.laxminarayan.bharadiya@intel.com \
--cc=songliubraving@fb.com \
--cc=tglx@linutronix.de \
--cc=toke@redhat.com \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).