From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E0F69267B07 for ; Fri, 26 Sep 2025 16:53:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758905636; cv=none; b=DY4EkTad45ePbF5BYKClm26EwsygWBQc7pygVWTwpRjf8+VA4Yywff5AV1xvaj5Uy/rYzyjVhf2TD36AgHT/4Yu/03xJRbkVmBOAeHBbhYmdWZJYxXwr2+6DfJlZV0QCbTOxQ2mhZ4oGzc4tHhw+Xq1/YyfjmXAr2SbFg0X8Vn0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758905636; c=relaxed/simple; bh=LwOJpW+sePplAG4eX66QcVDUAwVdGU5QRYA0F0ndEt0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mP4NsobHQtXs43JjqYzB5nN24GZVdHCsJLFrUwJxIYoyl1pPjkiaUCVEnV2i1xQ1EqsL8eEiE1JBnyDSYgEOvoj62spzYUFXNTnWxzQby9rW//hmKXa8E/0jvjLf8M0rAAz5WYE7Z0guiF2IhsryJXCDRPcKovz+lR6hVnHjboQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=AKxxMsJS; arc=none smtp.client-ip=95.215.58.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="AKxxMsJS" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1758905623; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FxQha2U3givTWX9Jey3JjHcMVKjbxrYi3ZLCeQ5vxsw=; b=AKxxMsJSpuanP0Rm7dhGi4SoTEpl2Csgqr0/89nSGlKItU958szk8s8HqBwyGYTK2X/ocl QcfbfZFc758ls8azpu84GabvqgIg5v3/V8ulCKxVJaATI9UZaw1iaMT5F0T1UUuvJmP/gI 1DtZZTIGpDgZ7CJ5M+z5vSAPSlArCN8= Date: Fri, 26 Sep 2025 09:53:33 -0700 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next] libbpf: fix error when st-prefix_ops and ops from differ btf To: "D. Wythe" Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, pabeni@redhat.com, song@kernel.org, sdf@google.com, haoluo@google.com, yhs@fb.com, edumazet@google.com, john.fastabend@gmail.com, kpsingh@kernel.org, jolsa@kernel.org, mjambigi@linux.ibm.com, wenjia@linux.ibm.com, wintera@linux.ibm.com, dust.li@linux.alibaba.com, tonylu@linux.alibaba.com, guwen@linux.alibaba.com, bpf@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, sidraya@linux.ibm.com, jaka@linux.ibm.com References: <20250926071751.108293-1-alibuda@linux.alibaba.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau Content-Language: en-US In-Reply-To: <20250926071751.108293-1-alibuda@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 9/26/25 12:17 AM, D. Wythe wrote: > When a module registers a struct_ops, the struct_ops type and its > corresponding map_value type ("bpf_struct_ops_") may reside in different > btf objects, here are four possible case: > > +--------+---------------+-------------+---------------------------------+ > | |bpf_struct_ops_| xxx_ops | | > +--------+---------------+-------------+---------------------------------+ > | case 0 | btf_vmlinux | bft_vmlinux | be used and reg only in vmlinux | s/bft/btf/ > +--------+---------------+-------------+---------------------------------+ > | case 1 | btf_vmlinux | mod_btf | INVALID | > +--------+---------------+-------------+---------------------------------+ > | case 2 | mod_btf | btf_vmlinux | reg in mod but be used both in | > | | | | vmlinux and mod. | > +--------+---------------+-------------+---------------------------------+ > | case 3 | mod_btf | mod_btf | be used and reg only in mod | > +--------+---------------+-------------+---------------------------------+ > > Currently we figure out the mod_btf by searching with the struct_ops type, > which makes it impossible to figure out the mod_btf when the struct_ops > type is in btf_vmlinux while it's corresponding map_value type is in > mod_btf (case 2). > > The fix is to use the corresponding map_value type ("bpf_struct_ops_") > as the lookup anchor instead of the struct_ops type to figure out the > `btf` and `mod_btf` via find_ksym_btf_id(), and then we can locate > the kern_type_id via btf__find_by_name_kind() with the `btf` we just > obtained from find_ksym_btf_id(). > > With this change the lookup obtains the correct btf and mod_btf for case 2, > preserves correct behavior for other valid cases, and still fails as > expected for the invalid scenario (case 1). > > Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support") > Signed-off-by: D. Wythe > Acked-by: Andrii Nakryiko > --- > tools/lib/bpf/libbpf.c | 37 ++++++++++++++++++------------------- > 1 file changed, 18 insertions(+), 19 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 5161c2b39875..a93eed660404 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -1018,35 +1018,34 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, > const struct btf_member *kern_data_member; > struct btf *btf = NULL; > __s32 kern_vtype_id, kern_type_id; > - char tname[256]; > + char tname[256], stname[256]; > __u32 i; > > snprintf(tname, sizeof(tname), "%.*s", > (int)bpf_core_essential_name_len(tname_raw), tname_raw); > > - kern_type_id = find_ksym_btf_id(obj, tname, BTF_KIND_STRUCT, > - &btf, mod_btf); > - if (kern_type_id < 0) { > - pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n", > - tname); > - return kern_type_id; > - } > - kern_type = btf__type_by_id(btf, kern_type_id); > + snprintf(stname, sizeof(stname), "%s%.*s", STRUCT_OPS_VALUE_PREFIX, > + (int)strlen(tname), tname); nit. strlen(tname) should not be needed. Others lgtm. Acked-by: Martin KaFai Lau