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From: Florian Weimer <fw@deneb.enyo.de>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	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 19:31:50 +0100	[thread overview]
Message-ID: <87o8jutt2h.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <20201118181226.GK2672@gate.crashing.org> (Segher Boessenkool's message of "Wed, 18 Nov 2020 12:12:26 -0600")

* Segher Boessenkool:

> On Wed, Nov 18, 2020 at 12:17:30PM -0500, Steven Rostedt wrote:
>> I could change the stub from (void) to () if that would be better.
>
> Don't?  In a function definition they mean exactly the same thing (and
> the kernel uses (void) everywhere else, which many people find clearer).

And I think () functions expected a caller-provided parameter save
area on powerpc64le, while (void) functions do not.  It does not
matter for an empty function, but GCC prefers to use the parameter
save area instead of setting up a stack frame if it is present.  So
you get stack corruption if you call a () function as a (void)
function.  (The other way round is fine.)

  reply	other threads:[~2020-11-18 18:32 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-16 22:51 [PATCH] tracepoint: Do not fail unregistering a probe due to memory allocation Steven Rostedt
2020-11-16 23:16 ` Steven Rostedt
2020-11-17 19:15 ` Mathieu Desnoyers
2020-11-17 19:21   ` Steven Rostedt
2020-11-17 19:47     ` Mathieu Desnoyers
2020-11-17 20:34       ` Steven Rostedt
2020-11-17 20:58         ` Steven Rostedt
2020-11-17 21:22           ` Mathieu Desnoyers
2020-11-17 22:16             ` Steven Rostedt
2020-11-17 23:08               ` Mathieu Desnoyers
2020-11-18  1:11                 ` Steven Rostedt
2020-11-17 21:08         ` Mathieu Desnoyers
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
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 [this message]
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
2020-11-17 21:33 ` [PATCH] tracepoint: Do not fail unregistering a probe due to memory allocation Kees Cook
2020-11-17 22:19   ` Steven Rostedt
2020-11-17 23:12     ` Mathieu Desnoyers

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