From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Matt Mullins <mmullins@mmlx.us>, Ingo Molnar <mingo@redhat.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Dmitry Vyukov <dvyukov@google.com>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>, netdev <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Kees Cook <keescook@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
linux-toolchains@vger.kernel.org
Subject: Re: violating function pointer signature
Date: Wed, 18 Nov 2020 09:02:56 -0500 [thread overview]
Message-ID: <20201118090256.55656208@gandalf.local.home> (raw)
In-Reply-To: <20201118132136.GJ3121378@hirez.programming.kicks-ass.net>
On Wed, 18 Nov 2020 14:21:36 +0100
Peter Zijlstra <peterz@infradead.org> wrote:
> I think that as long as the function is completely empty (it never
> touches any of the arguments) this should work in practise.
>
> That is:
>
> void tp_nop_func(void) { }
My original version (the OP of this thread) had this:
+static void tp_stub_func(void)
+{
+ return;
+}
>
> can be used as an argument to any function pointer that has a void
> return. In fact, I already do that, grep for __static_call_nop().
>
> I'm not sure what the LLVM-CFI crud makes of it, but that's their
> problem.
If it is already done elsewhere in the kernel, then I will call this
precedence, and keep the original version.
This way Alexei can't complain about adding a check in the fast path of
more than one callback attached.
-- Steve
next prev parent reply other threads:[~2020-11-18 14:03 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20201116175107.02db396d@gandalf.local.home>
[not found] ` <47463878.48157.1605640510560.JavaMail.zimbra@efficios.com>
[not found] ` <20201117142145.43194f1a@gandalf.local.home>
[not found] ` <375636043.48251.1605642440621.JavaMail.zimbra@efficios.com>
[not found] ` <20201117153451.3015c5c9@gandalf.local.home>
2020-11-18 13:21 ` violating function pointer signature Peter Zijlstra
2020-11-18 13:59 ` Florian Weimer
2020-11-18 14:12 ` Peter Zijlstra
2020-11-18 14:18 ` Florian Weimer
2020-11-18 14:34 ` [PATCH v3] tracepoint: Do not fail unregistering a probe due to memory allocation Steven Rostedt
2020-11-24 5:59 ` Matt Mullins
2020-11-18 14:22 ` violating function pointer signature Steven Rostedt
2020-11-18 19:46 ` Alexei Starovoitov
2020-11-18 20:02 ` Steven Rostedt
2020-11-18 14:02 ` Steven Rostedt [this message]
2020-11-18 16:01 ` Mathieu Desnoyers
2020-11-18 16:19 ` David Laight
2020-11-18 16:50 ` Nick Desaulniers
2020-11-18 17:17 ` Steven Rostedt
2020-11-18 18:12 ` Segher Boessenkool
2020-11-18 18:31 ` Florian Weimer
2020-11-18 18:55 ` Segher Boessenkool
2020-11-18 18:58 ` Steven Rostedt
2020-11-18 18:59 ` Steven Rostedt
2020-11-18 19:11 ` Segher Boessenkool
2020-11-18 19:33 ` Steven Rostedt
2020-11-18 19:48 ` Segher Boessenkool
2020-11-18 20:44 ` Steven Rostedt
2020-11-19 8:21 ` Peter Zijlstra
2020-11-19 8:36 ` Peter Zijlstra
2020-11-19 14:37 ` Segher Boessenkool
2020-11-19 14:59 ` Steven Rostedt
2020-11-19 16:35 ` Segher Boessenkool
2020-11-19 17:42 ` David Laight
2020-11-19 19:27 ` Segher Boessenkool
2020-11-19 17:04 ` Alexei Starovoitov
2020-11-19 17:30 ` Steven Rostedt
2020-11-20 1:31 ` Nick Desaulniers
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