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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Networking <netdev@vger.kernel.org>, bpf <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>
Subject: Re: [PATCH bpf-next 06/29] bpf: Add bpf_arg/bpf_ret_value helpers for tracing programs
Date: Wed, 1 Dec 2021 12:36:29 -0800	[thread overview]
Message-ID: <CAADnVQKjOGr+v-xA6JP2wriha6BFFA0cs8cdUY-74ft2YYzXkg@mail.gmail.com> (raw)
In-Reply-To: <CAEf4BzabQ9YU=d-F0ypA6W73YD534cAb2SkAkwYuyD6dk71LSQ@mail.gmail.com>

On Wed, Dec 1, 2021 at 10:00 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> But you emphasized an important point, that it's probably good to
> allow users to distinguish errors from reading actual value 0. There
> are and will be situations where argument isn't available or some
> combination of conditions are not supported. So I think, while it's a
> bit more verbose, these forms are generally better:
>
> int bpf_get_func_arg(int n, u64 *value);
> int bpf_get_func_ret(u64 *value);
>
> WDYT?

Makes sense to me.
The verifier will be able to inline it just fine.
Two extra insns only compared to direct return.

  reply	other threads:[~2021-12-01 20:38 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-18 11:24 [RFC bpf-next v5 00/29] bpf: Add batch support for attaching trampolines Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 01/29] ftrace: Use direct_ops hash in unregister_ftrace_direct Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 02/29] ftrace: Add cleanup to unregister_ftrace_direct_multi Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 03/29] ftrace: Add ftrace_set_filter_ips function Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 04/29] bpf: Factor bpf_check_attach_target function Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 05/29] bpf: Add bpf_check_attach_model function Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 06/29] bpf: Add bpf_arg/bpf_ret_value helpers for tracing programs Jiri Olsa
2021-11-24 21:43   ` Andrii Nakryiko
2021-11-25 16:14     ` Alexei Starovoitov
2021-11-28 18:07       ` Jiri Olsa
2021-11-28 18:06     ` Jiri Olsa
2021-12-01  7:13       ` Andrii Nakryiko
2021-12-01 17:37         ` Alexei Starovoitov
2021-12-01 17:59           ` Andrii Nakryiko
2021-12-01 20:36             ` Alexei Starovoitov [this message]
2021-12-01 21:16             ` Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 07/29] bpf, x64: Allow to use caller address from stack Jiri Olsa
2021-11-19  4:14   ` Alexei Starovoitov
2021-11-19 21:46     ` Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 08/29] bpf: Keep active attached trampoline in bpf_prog Jiri Olsa
2021-11-24 21:48   ` Andrii Nakryiko
2021-11-28 17:24     ` Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 09/29] bpf: Add support to load multi func tracing program Jiri Olsa
2021-11-19  4:11   ` Alexei Starovoitov
2021-11-22 20:15     ` Jiri Olsa
2021-11-24 21:51       ` Andrii Nakryiko
2021-11-28 17:41         ` Jiri Olsa
2021-12-01  7:17           ` Andrii Nakryiko
2021-12-01 21:20             ` Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 10/29] bpf: Add bpf_trampoline_id object Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 11/29] bpf: Add addr to " Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 12/29] bpf: Add struct bpf_tramp_node layer Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 13/29] bpf: Add bpf_tramp_attach layer for trampoline attachment Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 14/29] bpf: Add support to store multiple ids in bpf_tramp_id object Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 15/29] bpf: Add support to store multiple addrs " Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 16/29] bpf: Add bpf_tramp_id_single function Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 17/29] bpf: Resolve id in bpf_tramp_id_single Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 18/29] bpf: Add refcount_t to struct bpf_tramp_id Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 19/29] bpf: Add support to attach trampolines with multiple IDs Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 20/29] bpf: Add support for tracing multi link Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 21/29] libbpf: Add btf__find_by_glob_kind function Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 22/29] libbpf: Add support to link multi func tracing program Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 23/29] selftests/bpf: Add bpf_arg/bpf_ret_value test Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 24/29] selftests/bpf: Add fentry multi func test Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 25/29] selftests/bpf: Add fexit " Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 26/29] selftests/bpf: Add fentry/fexit " Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 27/29] selftests/bpf: Add mixed " Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 28/29] selftests/bpf: Add ret_mod " Jiri Olsa
2021-11-18 11:24 ` [PATCH bpf-next 29/29] selftests/bpf: Add attach " Jiri Olsa

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