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Wythe" X-Patchwork-Id: 13900827 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) (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 950DF2248B2; Tue, 10 Dec 2024 04:04:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.119 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733803460; cv=none; b=h1/ywEyqXVEXNy5lmMRR5SS/q/j33o2hIaUloG1S1LA3cp/OcbSz9iuIQ7PpuL24v7AEwhIbABJ/hXhqtOKrSNXHDbtrfi/iVPNe71w2x2imStt7FllOwSN2+lzzWC2s9WsFQsmWZIimxCpQxGx4lrvxBcE9Vv4b6xSqIDO198Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733803460; c=relaxed/simple; bh=AZOdek+RUNNOrIdFnpTnEdTFyhO7MNA3UCr2W4Qo4WY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ysf5ngO4DaSOybnIh0jvDes+Ow2gHjEKA1vPrtxurWNVlVOObzlG6IW26pYSr4HKz5lQ7v0M75tyBfJrcag8o0VdtnyN54CwGsrokU+XwUu9zAp9B1aFTqWvZV/1yRNdVz1ToXpBKSXXEUwIsA2x5zSgFow06RkxaghZt4kg73o= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=Mui6jyZx; arc=none smtp.client-ip=115.124.30.119 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="Mui6jyZx" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1733803454; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=3m/Oe9SBWSoTllrI9BCOOJJsHqYj/BHA8hL2sssyCyE=; b=Mui6jyZxjGczQf4SA10vYMxtcpEMGR/irecKq207IL/HHqJiFs6FkiRqazLJvAIosupyj9IQUW2zDh9u533FLcx1aTLTSnb47l/SlSU6Ie9ehJHeCW+O8Rw7sukLN6ySuSu+2mqsd3U6aVw+KFoWMUvLXGB05GED6CgnuCzZ5cg= Received: from j66a10360.sqa.eu95.tbsite.net(mailfrom:alibuda@linux.alibaba.com fp:SMTPD_---0WLDSEYV_1733803452 cluster:ay36) by smtp.aliyun-inc.com; Tue, 10 Dec 2024 12:04:12 +0800 From: "D. Wythe" To: kgraul@linux.ibm.com, wenjia@linux.ibm.com, jaka@linux.ibm.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, 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, guwen@linux.alibaba.com Cc: kuba@kernel.org, davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH bpf-next v2 4/5] libbpf: fix error when st-prefix_ops and ops from differ btf Date: Tue, 10 Dec 2024 12:04:03 +0800 Message-ID: <20241210040404.10606-5-alibuda@linux.alibaba.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20241210040404.10606-1-alibuda@linux.alibaba.com> References: <20241210040404.10606-1-alibuda@linux.alibaba.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net When a struct_ops named xxx_ops was registered by a module, and it will be used in both built-in modules and the module itself, so that the btf_type of xxx_ops will be present in btf_vmlinux instead of in btf_mod, which means that the btf_type of bpf_struct_ops_xxx_ops and xxx_ops will not be in the same btf. Here are four possible case: +--------+-------------+-------------+---------------------------------+ | | st_opx_xxx | xxx | | +--------+-------------+-------------+---------------------------------+ | case 0 | btf_vmlinux | bft_vmlinux | be used and reg only in vmlinux | +--------+-------------+-------------+---------------------------------+ | case 1 | btf_vmlinux | bpf_mod | INVALID | +--------+-------------+-------------+---------------------------------+ | case 2 | btf_mod | btf_vmlinux | reg in mod but be used both in | | | | | vmlinux and mod. | +--------+-------------+-------------+---------------------------------+ | case 3 | btf_mod | btf_mod | be used and reg only in mod | +--------+-------------+-------------+---------------------------------+ At present, cases 0, 1, and 3 can be correctly identified, because st_ops_xxx is searched from the same btf with xxx. In order to handle case 2 correctly without affecting other cases, we cannot simply change the search method for st_ops_xxx from find_btf_by_prefix_kind() to find_ksym_btf_id(), because in this way, case 1 will not be recognized anymore. To address this issue, if st_ops_xxx cannot be found in the btf with xxx and mod_btf does not exist, do find_ksym_btf_id() again to avoid such issue. Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support") Signed-off-by: D. Wythe --- tools/lib/bpf/libbpf.c | 34 +++++++++++++++++++++++++++++++--- 1 file changed, 31 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 66173ddb5a2d..046feab4ec36 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -994,6 +994,27 @@ static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name, static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix, const char *name, __u32 kind); +static int +find_ksym_btf_id_by_prefix_kind(struct bpf_object *obj, const char *prefix, + const char *name, + __u16 kind, struct btf **res_btf, + struct module_btf **res_mod_btf) +{ + char btf_type_name[128]; + int ret; + + ret = snprintf(btf_type_name, sizeof(btf_type_name), + "%s%s", prefix, name); + /* snprintf returns the number of characters written excluding the + * terminating null. So, if >= BTF_MAX_NAME_SIZE are written, it + * indicates truncation. + */ + if (ret < 0 || ret >= sizeof(btf_type_name)) + return -ENAMETOOLONG; + + return find_ksym_btf_id(obj, btf_type_name, kind, res_btf, res_mod_btf); +} + static int find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, struct module_btf **mod_btf, @@ -1028,9 +1049,16 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX, tname, BTF_KIND_STRUCT); if (kern_vtype_id < 0) { - pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n", - STRUCT_OPS_VALUE_PREFIX, tname); - return kern_vtype_id; + if (kern_vtype_id == -ENOENT && !*mod_btf) + kern_vtype_id = + find_ksym_btf_id_by_prefix_kind(obj, STRUCT_OPS_VALUE_PREFIX, + tname, BTF_KIND_STRUCT, &btf, + mod_btf); + if (kern_vtype_id < 0) { + pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n", + STRUCT_OPS_VALUE_PREFIX, tname); + return kern_vtype_id; + } } kern_vtype = btf__type_by_id(btf, kern_vtype_id);