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[23.128.96.18]) by mx.google.com with ESMTP id u13si2949605jak.109.2021.09.02.10.00.25; Thu, 02 Sep 2021 10:00:38 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@fb.com header.s=facebook header.b=OWaao3Ul; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=fb.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346429AbhIBQ6c (ORCPT + 99 others); Thu, 2 Sep 2021 12:58:32 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:42028 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346499AbhIBQ6U (ORCPT ); Thu, 2 Sep 2021 12:58:20 -0400 Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 182GqhpN032134 for ; Thu, 2 Sep 2021 09:57:21 -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-transfer-encoding : content-type; s=facebook; bh=pH8/nR2PqifgRk2kuwzHEB3by0fF+l7GC6tqeDa1XB4=; b=OWaao3Ul44rh3Vd1ACF6vQTZKzTSwvS0bm/QdwjLJwu+ZMtY6WgEVAcBw92/4JEldSZH lm001iEHV9bPfI/sqPA3CPnh70OiwlXKn0nYNCQPBtHPFGhClb+gY5XL/MH85YTPWpIa 0fPfybOmQQgBQgSEIEs/ZMbyZiRdKHSUoWs= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 3atdypk8m5-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 02 Sep 2021 09:57:21 -0700 Received: from intmgw002.06.ash9.facebook.com (2620:10d:c085:208::f) 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; Thu, 2 Sep 2021 09:57:20 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 36812FBB7C5B; Thu, 2 Sep 2021 09:57:18 -0700 (PDT) From: Song Liu To: , CC: , , , , , Song Liu Subject: [PATCH v5 bpf-next 2/3] bpf: introduce helper bpf_get_branch_snapshot Date: Thu, 2 Sep 2021 09:57:05 -0700 Message-ID: <20210902165706.2812867-3-songliubraving@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210902165706.2812867-1-songliubraving@fb.com> References: <20210902165706.2812867-1-songliubraving@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-FB-Source: Intern X-Proofpoint-GUID: JyEu-uW4olhTTT0LA6AyKbURKLMYwNZ3 X-Proofpoint-ORIG-GUID: JyEu-uW4olhTTT0LA6AyKbURKLMYwNZ3 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-09-02_04:2021-09-02,2021-09-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 adultscore=0 priorityscore=1501 suspectscore=0 mlxlogscore=999 phishscore=0 clxscore=1015 malwarescore=0 mlxscore=0 lowpriorityscore=0 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2108310000 definitions=main-2109020098 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Song Liu --- include/uapi/linux/bpf.h | 22 ++++++++++++++++++++++ kernel/bpf/trampoline.c | 3 ++- kernel/trace/bpf_trace.c | 33 +++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 22 ++++++++++++++++++++++ 4 files changed, 79 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 791f31dd0abee..c986e6fad5bc0 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 + * branch trace is taken soon after the trigger point of the + * BPF program, so it may contain some entries after the + * trigger point. The user need to filter these entries + * accordingly. + * + * 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 arguments invalid or **size** not a multiple + * of **sizeof**\ (**struct perf_branch_entry**\ ). + * + * **-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), \ /* */ =20 /* integer value in 'imm' field of BPF_CALL instruction selects which he= lper 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 =20 /* dummy _ops. The verifier will operate on target program's ops. */ const struct bpf_verifier_ops bpf_extension_verifier_ops =3D { @@ -526,7 +527,7 @@ void bpf_trampoline_put(struct bpf_trampoline *tr) } =20 #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 =3D NO_START_TIME; =20 diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 8e2eb950aa829..1954bc113087c 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1017,6 +1017,37 @@ static const struct bpf_func_proto bpf_get_attach_= cookie_proto_pe =3D { .arg1_type =3D ARG_PTR_TO_CTX, }; =20 +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 =3D sizeof(struct perf_branch_entry); + u32 entry_cnt =3D size / br_entry_size; + + if (unlikely(flags)) + return -EINVAL; + + if (!buf || (size % br_entry_size !=3D 0)) + return -EINVAL; + + entry_cnt =3D static_call(perf_snapshot_branch_stack)(buf, entry_cnt); + + if (!entry_cnt) + return -ENOENT; + + return entry_cnt * br_entry_size; +#endif +} + +static const struct bpf_func_proto bpf_get_branch_snapshot_proto =3D { + .func =3D bpf_get_branch_snapshot, + .gpl_only =3D true, + .ret_type =3D RET_INTEGER, + .arg1_type =3D ARG_PTR_TO_UNINIT_MEM, + .arg2_type =3D 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 +1163,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, co= nst 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/bp= f.h index 791f31dd0abee..c986e6fad5bc0 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 + * branch trace is taken soon after the trigger point of the + * BPF program, so it may contain some entries after the + * trigger point. The user need to filter these entries + * accordingly. + * + * 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 arguments invalid or **size** not a multiple + * of **sizeof**\ (**struct perf_branch_entry**\ ). + * + * **-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), \ /* */ =20 /* integer value in 'imm' field of BPF_CALL instruction selects which he= lper --=20 2.30.2