From patchwork Thu Oct 10 04:14:56 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexei Starovoitov X-Patchwork-Id: 1174260 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 46pd6F5MtYz9sPL for ; Thu, 10 Oct 2019 15:15:17 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728823AbfJJEPR convert rfc822-to-8bit (ORCPT ); Thu, 10 Oct 2019 00:15:17 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:16612 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728679AbfJJEPQ (ORCPT ); Thu, 10 Oct 2019 00:15:16 -0400 Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id x9A4F4VZ012057 for ; Wed, 9 Oct 2019 21:15:15 -0700 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 2vgvc018ey-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 09 Oct 2019 21:15:15 -0700 Received: from 2401:db00:2050:5102:face:0:3b:0 (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Wed, 9 Oct 2019 21:15:14 -0700 Received: by devbig007.ftw2.facebook.com (Postfix, from userid 572438) id 675CF760CEE; Wed, 9 Oct 2019 21:15:13 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Alexei Starovoitov Smtp-Origin-Hostname: devbig007.ftw2.facebook.com To: CC: , , , , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH v2 bpf-next 05/12] libbpf: auto-detect btf_id of raw_tracepoint Date: Wed, 9 Oct 2019 21:14:56 -0700 Message-ID: <20191010041503.2526303-6-ast@kernel.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191010041503.2526303-1-ast@kernel.org> References: <20191010041503.2526303-1-ast@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,1.0.8 definitions=2019-10-10_02:2019-10-08,2019-10-10 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 impostorscore=0 spamscore=0 priorityscore=1501 adultscore=0 bulkscore=0 lowpriorityscore=0 malwarescore=0 clxscore=1015 suspectscore=3 mlxlogscore=999 phishscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1908290000 definitions=main-1910100037 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org For raw tracepoint program types libbpf will try to find btf_id of raw tracepoint in vmlinux's BTF. It's a responsiblity of bpf program author to annotate the program with SEC("raw_tracepoint/name") where "name" is a valid raw tracepoint. If "name" is indeed a valid raw tracepoint then in-kernel BTF will have "btf_trace_##name" typedef that points to function prototype of that raw tracepoint. BTF description captures exact argument the kernel C code is passing into raw tracepoint. The kernel verifier will check the types while loading bpf program. libbpf keeps BTF type id in expected_attach_type, but since kernel ignores this attribute for tracing programs copy it into attach_btf_id attribute before loading. Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko --- tools/lib/bpf/bpf.c | 3 +++ tools/lib/bpf/libbpf.c | 17 +++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index cbb933532981..79046067720f 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -228,6 +228,9 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr, memset(&attr, 0, sizeof(attr)); attr.prog_type = load_attr->prog_type; attr.expected_attach_type = load_attr->expected_attach_type; + if (attr.prog_type == BPF_PROG_TYPE_RAW_TRACEPOINT) + /* expected_attach_type is ignored for tracing progs */ + attr.attach_btf_id = attr.expected_attach_type; attr.insn_cnt = (__u32)load_attr->insns_cnt; attr.insns = ptr_to_u64(load_attr->insns); attr.license = ptr_to_u64(load_attr->license); diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a02cdedc4e3f..8bf30a67428c 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -4586,6 +4586,23 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type, continue; *prog_type = section_names[i].prog_type; *expected_attach_type = section_names[i].expected_attach_type; + if (*prog_type == BPF_PROG_TYPE_RAW_TRACEPOINT) { + struct btf *btf = bpf_core_find_kernel_btf(); + char raw_tp_btf_name[128] = "btf_trace_"; + char *dst = raw_tp_btf_name + sizeof("btf_trace_") - 1; + int ret; + + if (IS_ERR(btf)) + /* lack of kernel BTF is not a failure */ + return 0; + /* prepend "btf_trace_" prefix per kernel convention */ + strncat(dst, name + section_names[i].len, + sizeof(raw_tp_btf_name) - (dst - raw_tp_btf_name)); + ret = btf__find_by_name(btf, raw_tp_btf_name); + if (ret > 0) + *expected_attach_type = ret; + btf__free(btf); + } return 0; } pr_warning("failed to guess program type based on ELF section name '%s'\n", name);