From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 C56C6C5B57A for ; Fri, 28 Jun 2019 05:53:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9E4862086D for ; Fri, 28 Jun 2019 05:53:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="WhIg+hU5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727114AbfF1FxZ (ORCPT ); Fri, 28 Jun 2019 01:53:25 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:57808 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727085AbfF1FxX (ORCPT ); Fri, 28 Jun 2019 01:53:23 -0400 Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.16.0.27/8.16.0.27) with SMTP id x5S5pQl5016637 for ; Thu, 27 Jun 2019 22:53:21 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=3PjbKb/nEUy6KfRKR954lOrQSKqJL81G3OLgg5ZPWTM=; b=WhIg+hU5/4NVaWtNzY4RnxotbX0TQD6i8RParE64RXjgRBq2uKfmDt+I23Ifv7eebvgK syMONVP86vCjbVOlvs7ZjUqS0ppSwSeHjKYTyI4kOS1oWX2FKNjoNsMqC5iPo0M4Sjlm 2nhQNDx/ho9C7RoOn+edaZ/xzaOQlTC2/Cs= Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by m0001303.ppops.net with ESMTP id 2tdabq8e9h-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Thu, 27 Jun 2019 22:53:21 -0700 Received: from mx-out.facebook.com (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::130) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Thu, 27 Jun 2019 22:53:20 -0700 Received: by dev101.prn2.facebook.com (Postfix, from userid 137359) id AC826861468; Thu, 27 Jun 2019 22:53:19 -0700 (PDT) Smtp-Origin-Hostprefix: dev From: Andrii Nakryiko Smtp-Origin-Hostname: dev101.prn2.facebook.com To: , , , , , , CC: Andrii Nakryiko Smtp-Origin-Cluster: prn2c23 Subject: [PATCH v3 bpf-next 5/9] libbpf: add tracepoint attach API Date: Thu, 27 Jun 2019 22:52:59 -0700 Message-ID: <20190628055303.1249758-6-andriin@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190628055303.1249758-1-andriin@fb.com> References: <20190628055303.1249758-1-andriin@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-28_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906280066 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Allow attaching BPF programs to kernel tracepoint BPF hooks specified by category and name. Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 78 ++++++++++++++++++++++++++++++++++++++++ tools/lib/bpf/libbpf.h | 4 +++ tools/lib/bpf/libbpf.map | 1 + 3 files changed, 83 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 65d2fef41003..76d1599a7d56 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -4229,6 +4229,84 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog, return link; } +static int determine_tracepoint_id(const char* tp_category, const char* tp_name) +{ + char file[PATH_MAX]; + int ret; + + ret = snprintf(file, sizeof(file), + "/sys/kernel/debug/tracing/events/%s/%s/id", + tp_category, tp_name); + if (ret < 0) + return -errno; + if (ret >= sizeof(file)) { + pr_debug("tracepoint %s/%s path is too long\n", + tp_category, tp_name); + return -E2BIG; + } + return parse_uint_from_file(file); +} + +static int perf_event_open_tracepoint(const char* tp_category, + const char* tp_name) +{ + struct perf_event_attr attr = {}; + char errmsg[STRERR_BUFSIZE]; + int tp_id, pfd, err; + + tp_id = determine_tracepoint_id(tp_category, tp_name); + if (tp_id < 0){ + pr_warning("failed to determine tracepoint '%s/%s' perf ID: %s\n", + tp_category, tp_name, + libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg))); + return tp_id; + } + + attr.type = PERF_TYPE_TRACEPOINT; + attr.size = sizeof(attr); + attr.config = tp_id; + + pfd = syscall( __NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */, + -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC); + if (pfd < 0) { + err = -errno; + pr_warning("tracepoint '%s/%s' perf_event_open() failed: %s\n", + tp_category, tp_name, + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); + return err; + } + return pfd; +} + +struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog, + const char *tp_category, + const char *tp_name) +{ + char errmsg[STRERR_BUFSIZE]; + struct bpf_link *link; + int pfd, err; + + pfd = perf_event_open_tracepoint(tp_category, tp_name); + if (pfd < 0) { + pr_warning("program '%s': failed to create tracepoint '%s/%s' perf event: %s\n", + bpf_program__title(prog, false), + tp_category, tp_name, + libbpf_strerror_r(pfd, errmsg, sizeof(errmsg))); + return ERR_PTR(pfd); + } + link = bpf_program__attach_perf_event(prog, pfd); + if (IS_ERR(link)) { + close(pfd); + err = PTR_ERR(link); + pr_warning("program '%s': failed to attach to tracepoint '%s/%s': %s\n", + bpf_program__title(prog, false), + tp_category, tp_name, + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); + return link; + } + return link; +} + enum bpf_perf_event_ret bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size, void **copy_mem, size_t *copy_size, diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index bd767cc11967..60611f4b4e1d 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -178,6 +178,10 @@ LIBBPF_API struct bpf_link * bpf_program__attach_uprobe(struct bpf_program *prog, bool retprobe, pid_t pid, const char *binary_path, size_t func_offset); +LIBBPF_API struct bpf_link * +bpf_program__attach_tracepoint(struct bpf_program *prog, + const char *tp_category, + const char *tp_name); struct bpf_insn; diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 57a40fb60718..3c618b75ef65 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -171,6 +171,7 @@ LIBBPF_0.0.4 { bpf_object__load_xattr; bpf_program__attach_kprobe; bpf_program__attach_perf_event; + bpf_program__attach_tracepoint; bpf_program__attach_uprobe; btf_dump__dump_type; btf_dump__free; -- 2.17.1