From patchwork Tue Jan 12 07:55:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 361705 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B83CBC43219 for ; Tue, 12 Jan 2021 07:56:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C64422E03 for ; Tue, 12 Jan 2021 07:56:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404241AbhALH4Y convert rfc822-to-8bit (ORCPT ); Tue, 12 Jan 2021 02:56:24 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:7167 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403970AbhALH4X (ORCPT ); Tue, 12 Jan 2021 02:56:23 -0500 Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 10C7rCDo013461 for ; Mon, 11 Jan 2021 23:55:42 -0800 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 35yw8798t6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 11 Jan 2021 23:55:42 -0800 Received: from intmgw001.03.ash8.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c085:11d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Mon, 11 Jan 2021 23:55:40 -0800 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 8A0BD2ECD646; Mon, 11 Jan 2021 23:55:36 -0800 (PST) From: Andrii Nakryiko To: , , , CC: , , Hao Luo , Yonghong Song Subject: [PATCH v3 bpf-next 6/7] libbpf: support kernel module ksym externs Date: Mon, 11 Jan 2021 23:55:19 -0800 Message-ID: <20210112075520.4103414-7-andrii@kernel.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20210112075520.4103414-1-andrii@kernel.org> References: <20210112075520.4103414-1-andrii@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.343, 18.0.737 definitions=2021-01-12_03:2021-01-11,2021-01-12 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 lowpriorityscore=0 adultscore=0 priorityscore=1501 suspectscore=0 mlxscore=0 spamscore=0 mlxlogscore=999 bulkscore=0 clxscore=1015 impostorscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101120042 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Add support for searching for ksym externs not just in vmlinux BTF, but across all module BTFs, similarly to how it's done for CO-RE relocations. Kernels that expose module BTFs through sysfs are assumed to support new ldimm64 instruction extension with BTF FD provided in insn[1].imm field, so no extra feature detection is performed. Acked-by: Yonghong Song Acked-by: Hao Luo Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 50 +++++++++++++++++++++++++++--------------- 1 file changed, 32 insertions(+), 18 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 6ae748f6ea11..2abbc3800568 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -395,7 +395,8 @@ struct extern_desc { unsigned long long addr; /* target btf_id of the corresponding kernel var. */ - int vmlinux_btf_id; + int kernel_btf_obj_fd; + int kernel_btf_id; /* local btf_id of the ksym extern's type. */ __u32 type_id; @@ -6162,7 +6163,8 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog) } else /* EXT_KSYM */ { if (ext->ksym.type_id) { /* typed ksyms */ insn[0].src_reg = BPF_PSEUDO_BTF_ID; - insn[0].imm = ext->ksym.vmlinux_btf_id; + insn[0].imm = ext->ksym.kernel_btf_id; + insn[1].imm = ext->ksym.kernel_btf_obj_fd; } else { /* typeless ksyms */ insn[0].imm = (__u32)ext->ksym.addr; insn[1].imm = ext->ksym.addr >> 32; @@ -7319,7 +7321,8 @@ static int bpf_object__read_kallsyms_file(struct bpf_object *obj) static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) { struct extern_desc *ext; - int i, id; + struct btf *btf; + int i, j, id, btf_fd, err; for (i = 0; i < obj->nr_extern; i++) { const struct btf_type *targ_var, *targ_type; @@ -7331,10 +7334,25 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) if (ext->type != EXT_KSYM || !ext->ksym.type_id) continue; - id = btf__find_by_name_kind(obj->btf_vmlinux, ext->name, - BTF_KIND_VAR); + btf = obj->btf_vmlinux; + btf_fd = 0; + id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR); + if (id == -ENOENT) { + err = load_module_btfs(obj); + if (err) + return err; + + for (j = 0; j < obj->btf_module_cnt; j++) { + btf = obj->btf_modules[j].btf; + /* we assume module BTF FD is always >0 */ + btf_fd = obj->btf_modules[j].fd; + id = btf__find_by_name_kind(btf, ext->name, BTF_KIND_VAR); + if (id != -ENOENT) + break; + } + } if (id <= 0) { - pr_warn("extern (ksym) '%s': failed to find BTF ID in vmlinux BTF.\n", + pr_warn("extern (ksym) '%s': failed to find BTF ID in kernel BTF(s).\n", ext->name); return -ESRCH; } @@ -7343,24 +7361,19 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) local_type_id = ext->ksym.type_id; /* find target type_id */ - targ_var = btf__type_by_id(obj->btf_vmlinux, id); - targ_var_name = btf__name_by_offset(obj->btf_vmlinux, - targ_var->name_off); - targ_type = skip_mods_and_typedefs(obj->btf_vmlinux, - targ_var->type, - &targ_type_id); + targ_var = btf__type_by_id(btf, id); + targ_var_name = btf__name_by_offset(btf, targ_var->name_off); + targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id); ret = bpf_core_types_are_compat(obj->btf, local_type_id, - obj->btf_vmlinux, targ_type_id); + btf, targ_type_id); if (ret <= 0) { const struct btf_type *local_type; const char *targ_name, *local_name; local_type = btf__type_by_id(obj->btf, local_type_id); - local_name = btf__name_by_offset(obj->btf, - local_type->name_off); - targ_name = btf__name_by_offset(obj->btf_vmlinux, - targ_type->name_off); + local_name = btf__name_by_offset(obj->btf, local_type->name_off); + targ_name = btf__name_by_offset(btf, targ_type->name_off); pr_warn("extern (ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n", ext->name, local_type_id, @@ -7370,7 +7383,8 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj) } ext->is_set = true; - ext->ksym.vmlinux_btf_id = id; + ext->ksym.kernel_btf_obj_fd = btf_fd; + ext->ksym.kernel_btf_id = id; pr_debug("extern (ksym) '%s': resolved to [%d] %s %s\n", ext->name, id, btf_kind_str(targ_var), targ_var_name); }