linux-kernel - Re: [PATCH v4 1/1] libbpf: fix USDT SIB argument handling causing unrecognized register error

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Message-ID: <CAADnVQKNGHGuu0GQR=HSCwvV9tm2dS6noKMcou=OEVp6T43NhQ@mail.gmail.com>
Date: Fri, 1 Aug 2025 18:10:07 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Jiawei Zhao <phoenix500526@....com>
Cc: Andrii Nakryiko <andrii@...nel.org>, Alexei Starovoitov <ast@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Yonghong Song <yonghong.song@...ux.dev>, 
	LKML <linux-kernel@...r.kernel.org>, 
	"open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH v4 1/1] libbpf: fix USDT SIB argument handling causing
 unrecognized register error

On Fri, Aug 1, 2025 at 9:16 AM Jiawei Zhao <phoenix500526@....com> wrote:
>
> From: Jiawei Zhao <Phoenix500526@....com>
>
> On x86-64, USDT arguments can be specified using Scale-Index-Base (SIB)
> addressing, e.g. "1@-96(%rbp,%rax,8)". The current USDT implementation
> in libbpf cannot parse this format, causing `bpf_program__attach_usdt()`
> to fail with -ENOENT (unrecognized register).
>
> This patch fixes this by implementing the necessary changes:
> - add correct handling for SIB-addressed arguments in `bpf_usdt_arg`.
> - add adaptive support to `__bpf_usdt_arg_type` and
> `__bpf_usdt_arg_spec` to represent SIB addressing parameters.
>
> Signed-off-by: Jiawei Zhao <Phoenix500526@....com>
> ---
>  tools/lib/bpf/usdt.bpf.h                      | 33 +++++++++++++-
>  tools/lib/bpf/usdt.c                          | 43 ++++++++++++++++---
>  tools/testing/selftests/bpf/Makefile          |  5 +++
>  tools/testing/selftests/bpf/prog_tests/usdt.c | 18 +++++---
>  4 files changed, 86 insertions(+), 13 deletions(-)

You didn't cc bpf@...r. It cannot land this way.
Pls respin and split libbpf vs selftest into separate patches.

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