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From: Leon Hwang <leon.hwang@linux.dev>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Kafai Wan <mannkafai@gmail.com>, Song Liu <song@kernel.org>,
	Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Eduard <eddyz87@gmail.com>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
	Matt Bobrowski <mattbobrowski@google.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Simon Horman <horms@kernel.org>, Mykola Lysenko <mykolal@fb.com>,
	Shuah Khan <shuah@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	linux-trace-kernel <linux-trace-kernel@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	"open list:KERNEL SELFTEST FRAMEWORK"
	<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH bpf-next 1/4] bpf: Allow get_func_[arg|arg_cnt] helpers in raw tracepoint programs
Date: Tue, 13 May 2025 00:01:50 +0800	[thread overview]
Message-ID: <e2bd2bd0-cb0f-4eef-896e-f1569b40243f@linux.dev> (raw)
In-Reply-To: <CAADnVQJNekoXnai0VGOVj8Q3e5RPtTXhNRjdfxF_PxjoQLDYRA@mail.gmail.com>



On 2025/5/12 23:25, Alexei Starovoitov wrote:
> On Mon, May 12, 2025 at 4:12 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>>

[...]

>>
>> However, since bpf_rdonly_cast() is a kfunc, it causes registers r1–r5
>> to be considered volatile.
> 
> It is not.
> See:
> BTF_ID_FLAGS(func, bpf_rdonly_cast, KF_FASTCALL)
> and relevant commits.

Thanks for the reminder — you're right, bpf_rdonly_cast() is marked with
KF_FASTCALL, so it doesn't make r1–r5 volatile.

Thanks,
Leon


  reply	other threads:[~2025-05-12 16:02 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-26 16:00 [PATCH bpf-next 0/4] bpf: Allow get_func_[arg|arg_cnt] helpers in raw tracepoint programs KaFai Wan
2025-04-26 16:00 ` [PATCH bpf-next 1/4] " KaFai Wan
2025-04-30  2:46   ` Alexei Starovoitov
2025-04-30 12:43     ` Kafai Wan
2025-04-30 15:54       ` Leon Hwang
2025-04-30 16:53         ` Alexei Starovoitov
2025-05-02 14:25           ` Leon Hwang
2025-05-06 21:01             ` Andrii Nakryiko
2025-05-12 11:12               ` Leon Hwang
2025-05-12 15:25                 ` Alexei Starovoitov
2025-05-12 16:01                   ` Leon Hwang [this message]
2025-05-01 20:53       ` Andrii Nakryiko
2025-04-26 16:00 ` [PATCH bpf-next 2/4] bpf: Enable BPF_PROG_TEST_RUN for tp_btf KaFai Wan
2025-05-01 20:55   ` Andrii Nakryiko
2025-04-26 16:00 ` [PATCH bpf-next 3/4] selftests/bpf: Add raw_tp_test_run " KaFai Wan
2025-04-26 16:00 ` [PATCH bpf-next 4/4] selftests/bpf: Add tests for get_func_[arg|arg_cnt] helpers in raw tracepoint programs KaFai Wan

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