From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
bpf@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>
Subject: Re: [PATCH bpf] bpf: Fix dispatcher patchable function entry to 5 bytes nop
Date: Tue, 18 Oct 2022 16:26:12 +0200 [thread overview]
Message-ID: <Y063hLFH1JXtdg7Y@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20221018075934.574415-1-jolsa@kernel.org>
On Tue, Oct 18, 2022 at 09:59:34AM +0200, Jiri Olsa wrote:
> The patchable_function_entry(5) might output 5 single nop
> instructions (depends on toolchain), which will clash with
> bpf_arch_text_poke check for 5 bytes nop instruction.
>
> Adding early init call for dispatcher that checks and change
> the patchable entry into expected 5 nop instruction if needed.
>
> There's no need to take text_mutex, because we are using it
> in early init call which is called at pre-smp time.
>
> Fixes: ceea991a019c ("bpf: Move bpf_dispatcher function out of ftrace locations")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
next prev parent reply other threads:[~2022-10-18 14:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-18 7:59 [PATCH bpf] bpf: Fix dispatcher patchable function entry to 5 bytes nop Jiri Olsa
2022-10-18 14:26 ` Peter Zijlstra [this message]
2022-10-21 2:10 ` patchwork-bot+netdevbpf
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