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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 184F6C433F5 for ; Thu, 28 Apr 2022 18:54:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348911AbiD1S5N convert rfc822-to-8bit (ORCPT ); Thu, 28 Apr 2022 14:57:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236775AbiD1S5M (ORCPT ); Thu, 28 Apr 2022 14:57:12 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 035FEB9F1F for ; Thu, 28 Apr 2022 11:53:56 -0700 (PDT) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 23SIPHfJ026723 for ; Thu, 28 Apr 2022 11:53:56 -0700 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3fprsrxuvx-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 28 Apr 2022 11:53:56 -0700 Received: from twshared29473.14.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::d) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 28 Apr 2022 11:53:54 -0700 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 209AB19360489; Thu, 28 Apr 2022 11:53:52 -0700 (PDT) From: Andrii Nakryiko To: , , CC: , , Delyan Kratunov , Jiri Olsa , Song Liu Subject: [PATCH v2 bpf-next 1/3] libbpf: allow "incomplete" basic tracing SEC() definitions Date: Thu, 28 Apr 2022 11:53:47 -0700 Message-ID: <20220428185349.3799599-2-andrii@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220428185349.3799599-1-andrii@kernel.org> References: <20220428185349.3799599-1-andrii@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-ORIG-GUID: sUpgTEQK1Z6pkjPW_gGGpMCmzWYTDjnt X-Proofpoint-GUID: sUpgTEQK1Z6pkjPW_gGGpMCmzWYTDjnt X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-04-28_03,2022-04-28_01,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org In a lot of cases the target of kprobe/kretprobe, tracepoint, raw tracepoint, etc BPF program might not be known at the compilation time and will be discovered at runtime. This was always a supported case by libbpf, with APIs like bpf_program__attach_{kprobe,tracepoint,etc}() accepting full target definition, regardless of what was defined in SEC() definition in BPF source code. Unfortunately, up till now libbpf still enforced users to specify at least something for the fake target, e.g., SEC("kprobe/whatever"), which is cumbersome and somewhat misleading. This patch allows target-less SEC() definitions for basic tracing BPF program types: - kprobe/kretprobe; - multi-kprobe/multi-kretprobe; - tracepoints; - raw tracepoints. Such target-less SEC() definitions are meant to specify declaratively proper BPF program type only. Attachment of them will have to be handled programmatically using correct APIs. As such, skeleton's auto-attachment of such BPF programs is skipped and generic bpf_program__attach() will fail, if attempted, due to the lack of enough target information. Acked-by: Song Liu Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 69 +++++++++++++++++++++++++++++++----------- 1 file changed, 51 insertions(+), 18 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 73a5192defb3..e840e48d3a76 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -8853,22 +8853,22 @@ static const struct bpf_sec_def section_defs[] = { SEC_DEF("socket", SOCKET_FILTER, 0, SEC_NONE | SEC_SLOPPY_PFX), SEC_DEF("sk_reuseport/migrate", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE | SEC_SLOPPY_PFX), SEC_DEF("sk_reuseport", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE | SEC_SLOPPY_PFX), - SEC_DEF("kprobe/", KPROBE, 0, SEC_NONE, attach_kprobe), + SEC_DEF("kprobe+", KPROBE, 0, SEC_NONE, attach_kprobe), SEC_DEF("uprobe+", KPROBE, 0, SEC_NONE, attach_uprobe), - SEC_DEF("kretprobe/", KPROBE, 0, SEC_NONE, attach_kprobe), + SEC_DEF("kretprobe+", KPROBE, 0, SEC_NONE, attach_kprobe), SEC_DEF("uretprobe+", KPROBE, 0, SEC_NONE, attach_uprobe), - SEC_DEF("kprobe.multi/", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi), - SEC_DEF("kretprobe.multi/", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi), + SEC_DEF("kprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi), + SEC_DEF("kretprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi), SEC_DEF("usdt+", KPROBE, 0, SEC_NONE, attach_usdt), SEC_DEF("tc", SCHED_CLS, 0, SEC_NONE), SEC_DEF("classifier", SCHED_CLS, 0, SEC_NONE | SEC_SLOPPY_PFX | SEC_DEPRECATED), SEC_DEF("action", SCHED_ACT, 0, SEC_NONE | SEC_SLOPPY_PFX), - SEC_DEF("tracepoint/", TRACEPOINT, 0, SEC_NONE, attach_tp), - SEC_DEF("tp/", TRACEPOINT, 0, SEC_NONE, attach_tp), - SEC_DEF("raw_tracepoint/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp), - SEC_DEF("raw_tp/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp), - SEC_DEF("raw_tracepoint.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp), - SEC_DEF("raw_tp.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp), + SEC_DEF("tracepoint+", TRACEPOINT, 0, SEC_NONE, attach_tp), + SEC_DEF("tp+", TRACEPOINT, 0, SEC_NONE, attach_tp), + SEC_DEF("raw_tracepoint+", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp), + SEC_DEF("raw_tp+", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp), + SEC_DEF("raw_tracepoint.w+", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp), + SEC_DEF("raw_tp.w+", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp), SEC_DEF("tp_btf/", TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace), SEC_DEF("fentry/", TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace), SEC_DEF("fmod_ret/", TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace), @@ -10595,6 +10595,12 @@ static int attach_kprobe(const struct bpf_program *prog, long cookie, struct bpf char *func; int n; + *link = NULL; + + /* no auto-attach for SEC("kprobe") and SEC("kretprobe") */ + if (strcmp(prog->sec_name, "kprobe") == 0 || strcmp(prog->sec_name, "kretprobe") == 0) + return 0; + opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe/"); if (opts.retprobe) func_name = prog->sec_name + sizeof("kretprobe/") - 1; @@ -10625,6 +10631,13 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru char *pattern; int n; + *link = NULL; + + /* no auto-attach for SEC("kprobe.multi") and SEC("kretprobe.multi") */ + if (strcmp(prog->sec_name, "kprobe.multi") == 0 || + strcmp(prog->sec_name, "kretprobe.multi") == 0) + return 0; + opts.retprobe = str_has_pfx(prog->sec_name, "kretprobe.multi/"); if (opts.retprobe) spec = prog->sec_name + sizeof("kretprobe.multi/") - 1; @@ -11329,6 +11342,12 @@ static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_lin if (!sec_name) return -ENOMEM; + *link = NULL; + + /* no auto-attach for SEC("tp") or SEC("tracepoint") */ + if (strcmp(prog->sec_name, "tp") == 0 || strcmp(prog->sec_name, "tracepoint") == 0) + return 0; + /* extract "tp//" or "tracepoint//" */ if (str_has_pfx(prog->sec_name, "tp/")) tp_cat = sec_name + sizeof("tp/") - 1; @@ -11380,20 +11399,34 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *pr static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link) { static const char *const prefixes[] = { - "raw_tp/", - "raw_tracepoint/", - "raw_tp.w/", - "raw_tracepoint.w/", + "raw_tp", + "raw_tracepoint", + "raw_tp.w", + "raw_tracepoint.w", }; size_t i; const char *tp_name = NULL; + *link = NULL; + for (i = 0; i < ARRAY_SIZE(prefixes); i++) { - if (str_has_pfx(prog->sec_name, prefixes[i])) { - tp_name = prog->sec_name + strlen(prefixes[i]); - break; - } + size_t pfx_len; + + if (!str_has_pfx(prog->sec_name, prefixes[i])) + continue; + + pfx_len = strlen(prefixes[i]); + /* no auto-attach case of, e.g., SEC("raw_tp") */ + if (prog->sec_name[pfx_len] == '\0') + return 0; + + if (prog->sec_name[pfx_len] != '/') + continue; + + tp_name = prog->sec_name + pfx_len + 1; + break; } + if (!tp_name) { pr_warn("prog '%s': invalid section name '%s'\n", prog->name, prog->sec_name); -- 2.30.2