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From: Eduard Zingerman <eddyz87@gmail.com>
To: "Xu Kuohai" <xukuohai@huaweicloud.com>,
	"Alexis Lothoré" <alexis.lothore@bootlin.com>,
	"Andrii Nakryiko" <andrii.nakryiko@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	 John Fastabend <john.fastabend@gmail.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau	 <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song	 <yonghong.song@linux.dev>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev	 <sdf@fomichev.me>,
	Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
	 Puranjay Mohan <puranjay@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,  Mykola Lysenko	 <mykolal@fb.com>,
	Shuah Khan <shuah@kernel.org>,
	Maxime Coquelin	 <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	 Florent Revest <revest@chromium.org>,
	Bastien Curutchet <bastien.curutchet@bootlin.com>,
	 ebpf@linuxfoundation.org,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	 bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	 linux-arm-kernel@lists.infradead.org,
	linux-kselftest@vger.kernel.org,
	 linux-stm32@st-md-mailman.stormreply.com
Subject: Re: [PATCH RFC bpf-next 1/4] bpf: add struct largest member size in func model
Date: Mon, 28 Apr 2025 00:11:46 -0700	[thread overview]
Message-ID: <b6878f60a62c4c6b4b7daa2272a18280e8fc362b.camel@gmail.com> (raw)
In-Reply-To: <2f13f928-9148-44e0-a44c-872a3779b0ef@huaweicloud.com>

On Fri, 2025-04-25 at 17:23 +0800, Xu Kuohai wrote:

[...]

> For the two questions you mentioned, I’m not sure if we can access DWARF attributes
> at runtime. As for adding parameter locations to BTF at building time, I think it
> means we would need to record CPU-related register info in BTF, which I don’t think
> is a good idea.

Another option would be for pahole to check if function parameter
DW_AT_locaction is placed in accordance with ABI.
These flags can be recorded in a dedicated section or smth like this.
Having said that, DW_AT_locaction seem to be not very reliable.
E.g. for bpf_testmod.ko generated by clang 19.1.7 I don't see
DW_AT_locaction specified for parameters a, b, c.



  reply	other threads:[~2025-04-28  7:17 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-11 20:32 [PATCH RFC bpf-next 0/4] bpf, arm64: support up to 12 arguments Alexis Lothoré (eBPF Foundation)
2025-04-11 20:32 ` [PATCH RFC bpf-next 1/4] bpf: add struct largest member size in func model Alexis Lothoré (eBPF Foundation)
2025-04-14 11:04   ` Jiri Olsa
2025-04-14 20:27     ` Alexis Lothoré
2025-04-16 21:24   ` Andrii Nakryiko
2025-04-17  7:14     ` Alexis Lothoré
2025-04-17 14:10       ` Xu Kuohai
2025-04-20 16:02         ` Alexis Lothoré
2025-04-21  2:14           ` Xu Kuohai
2025-04-23 15:38             ` Alexis Lothoré
2025-04-23 17:15       ` Andrii Nakryiko
2025-04-23 19:24         ` Alexis Lothoré
2025-04-24 12:00           ` Xu Kuohai
2025-04-24 13:38             ` Alexis Lothoré
2025-04-24 23:14               ` Alexei Starovoitov
2025-04-25  8:47                 ` Alexis Lothoré
2025-04-25  9:23               ` Xu Kuohai
2025-04-28  7:11                 ` Eduard Zingerman [this message]
     [not found]           ` <DADMLIVHMSSO.3AXSI5216WCT6@bootlin.com>
2025-06-04 17:31             ` [Question] attributes encoding in BTF Ihor Solodrai
2025-06-05  7:35               ` Alexis Lothoré
2025-06-05 16:09                 ` Alexei Starovoitov
2025-06-06  7:45                   ` Alexis Lothoré
2025-06-06 16:22                     ` Alexei Starovoitov
2025-04-11 20:32 ` [PATCH RFC bpf-next 2/4] bpf, arm64: Support up to 12 function arguments Alexis Lothoré
2025-04-11 20:32 ` [PATCH RFC bpf-next 3/4] bpf/selftests: add tests to validate proper arguments alignment on ARM64 Alexis Lothoré (eBPF Foundation)
2025-04-28  7:01   ` Eduard Zingerman
2025-04-28 10:08     ` Alexis Lothoré
2025-04-28 16:52       ` Eduard Zingerman
2025-04-28 20:41         ` Alexis Lothoré
2025-04-29  9:49           ` Alexis Lothoré
2025-04-11 20:32 ` [PATCH RFC bpf-next 4/4] bpf/selftests: enable tracing tests for ARM64 Alexis Lothoré (eBPF Foundation)

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