From patchwork Fri Sep 10 18:33:51 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12485685 X-Patchwork-Delegate: bpf@iogearbox.net 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 62297C433EF for ; Fri, 10 Sep 2021 18:34:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47D7B611EF for ; Fri, 10 Sep 2021 18:34:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232209AbhIJSfR (ORCPT ); Fri, 10 Sep 2021 14:35:17 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:63942 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229523AbhIJSfP (ORCPT ); Fri, 10 Sep 2021 14:35:15 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 18AIVRqX025420 for ; Fri, 10 Sep 2021 11:34:04 -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-transfer-encoding : content-type; s=facebook; bh=YMhudgSnNK/DoRnkGT2S8DkNAHFpeKIKyVhGGUUs4ag=; b=IrET1FpymW0zjKWtg52fG3vXampMfdtQ6YY7N+9pl+TZCpI/JcY4gaB2Pttkts+4zNy2 BSZ9wrNs6QFJ1EDkdmnfzyoWz7YdHAEvE8JKt+dL7gS9bXKUzsydmqG1binbww/DB2tf G+X+M7TTBIpjMPzWUvCqMOmKCFpmnhlTekA= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 3aytg0pqg3-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 10 Sep 2021 11:34:03 -0700 Received: from intmgw001.06.ash9.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:11d::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.14; Fri, 10 Sep 2021 11:34:02 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id DD51910A9148C; Fri, 10 Sep 2021 11:34:01 -0700 (PDT) From: Song Liu To: , CC: , , , , , Song Liu , John Fastabend , Andrii Nakryiko Subject: [PATCH v7 bpf-next 2/3] bpf: introduce helper bpf_get_branch_snapshot Date: Fri, 10 Sep 2021 11:33:51 -0700 Message-ID: <20210910183352.3151445-3-songliubraving@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210910183352.3151445-1-songliubraving@fb.com> References: <20210910183352.3151445-1-songliubraving@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-FB-Source: Intern X-Proofpoint-GUID: KUCH0-KpSUyDtgWQfwdkwYwu3_5-_hPN X-Proofpoint-ORIG-GUID: KUCH0-KpSUyDtgWQfwdkwYwu3_5-_hPN X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-09-10_07:2021-09-09,2021-09-10 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 impostorscore=0 spamscore=0 bulkscore=0 suspectscore=0 lowpriorityscore=0 adultscore=0 priorityscore=1501 mlxlogscore=999 malwarescore=0 clxscore=1015 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109030001 definitions=main-2109100106 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Introduce bpf_get_branch_snapshot(), which allows tracing pogram to get branch trace from hardware (e.g. Intel LBR). To use the feature, the user need to create perf_event with proper branch_record filtering on each cpu, and then calls bpf_get_branch_snapshot in the bpf function. On Intel CPUs, VLBR event (raw event 0x1b00) can be use for this. Acked-by: John Fastabend Acked-by: Andrii Nakryiko Signed-off-by: Song Liu --- include/uapi/linux/bpf.h | 22 ++++++++++++++++++++++ kernel/bpf/trampoline.c | 3 ++- kernel/trace/bpf_trace.c | 30 ++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 22 ++++++++++++++++++++++ 4 files changed, 76 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 791f31dd0abee..b695ef151001e 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4877,6 +4877,27 @@ union bpf_attr { * Get the struct pt_regs associated with **task**. * Return * A pointer to struct pt_regs. + * + * long bpf_get_branch_snapshot(void *entries, u32 size, u64 flags) + * Description + * Get branch trace from hardware engines like Intel LBR. The + * hardware engine is stopped shortly after the helper is + * called. Therefore, the user need to filter branch entries + * based on the actual use case. To capture branch trace + * before the trigger point of the BPF program, the helper + * should be called at the beginning of the BPF program. + * + * The data is stored as struct perf_branch_entry into output + * buffer *entries*. *size* is the size of *entries* in bytes. + * *flags* is reserved for now and must be zero. + * + * Return + * On success, number of bytes written to *buf*. On error, a + * negative value. + * + * **-EINVAL** if *flags* is not zero. + * + * **-ENOENT** if architecture does not support branch records. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5055,6 +5076,7 @@ union bpf_attr { FN(get_func_ip), \ FN(get_attach_cookie), \ FN(task_pt_regs), \ + FN(get_branch_snapshot), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index fe1e857324e66..39eaaff81953d 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -10,6 +10,7 @@ #include #include #include +#include /* dummy _ops. The verifier will operate on target program's ops. */ const struct bpf_verifier_ops bpf_extension_verifier_ops = { @@ -526,7 +527,7 @@ void bpf_trampoline_put(struct bpf_trampoline *tr) } #define NO_START_TIME 1 -static u64 notrace bpf_prog_start_time(void) +static __always_inline u64 notrace bpf_prog_start_time(void) { u64 start = NO_START_TIME; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 8e2eb950aa829..067e88c3d2ee5 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1017,6 +1017,34 @@ static const struct bpf_func_proto bpf_get_attach_cookie_proto_pe = { .arg1_type = ARG_PTR_TO_CTX, }; +BPF_CALL_3(bpf_get_branch_snapshot, void *, buf, u32, size, u64, flags) +{ +#ifndef CONFIG_X86 + return -ENOENT; +#else + static const u32 br_entry_size = sizeof(struct perf_branch_entry); + u32 entry_cnt = size / br_entry_size; + + entry_cnt = static_call(perf_snapshot_branch_stack)(buf, entry_cnt); + + if (unlikely(flags)) + return -EINVAL; + + if (!entry_cnt) + return -ENOENT; + + return entry_cnt * br_entry_size; +#endif +} + +static const struct bpf_func_proto bpf_get_branch_snapshot_proto = { + .func = bpf_get_branch_snapshot, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_UNINIT_MEM, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, +}; + static const struct bpf_func_proto * bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -1132,6 +1160,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_snprintf_proto; case BPF_FUNC_get_func_ip: return &bpf_get_func_ip_proto_tracing; + case BPF_FUNC_get_branch_snapshot: + return &bpf_get_branch_snapshot_proto; default: return bpf_base_func_proto(func_id); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 791f31dd0abee..b695ef151001e 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -4877,6 +4877,27 @@ union bpf_attr { * Get the struct pt_regs associated with **task**. * Return * A pointer to struct pt_regs. + * + * long bpf_get_branch_snapshot(void *entries, u32 size, u64 flags) + * Description + * Get branch trace from hardware engines like Intel LBR. The + * hardware engine is stopped shortly after the helper is + * called. Therefore, the user need to filter branch entries + * based on the actual use case. To capture branch trace + * before the trigger point of the BPF program, the helper + * should be called at the beginning of the BPF program. + * + * The data is stored as struct perf_branch_entry into output + * buffer *entries*. *size* is the size of *entries* in bytes. + * *flags* is reserved for now and must be zero. + * + * Return + * On success, number of bytes written to *buf*. On error, a + * negative value. + * + * **-EINVAL** if *flags* is not zero. + * + * **-ENOENT** if architecture does not support branch records. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5055,6 +5076,7 @@ union bpf_attr { FN(get_func_ip), \ FN(get_attach_cookie), \ FN(task_pt_regs), \ + FN(get_branch_snapshot), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper