From patchwork Wed Sep 1 00:35:15 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12468007 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, 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 2B469C4320E for ; Wed, 1 Sep 2021 00:35:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 124AE61053 for ; Wed, 1 Sep 2021 00:35:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241447AbhIAAg3 (ORCPT ); Tue, 31 Aug 2021 20:36:29 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:51700 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S230062AbhIAAg2 (ORCPT ); Tue, 31 Aug 2021 20:36:28 -0400 Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.16.0.43/8.16.0.43) with SMTP id 1810Xf4g002701 for ; Tue, 31 Aug 2021 17:35:32 -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=M+oSr91wZM4AdpVJbkwn+Sn6mz/eExc1SXQ25sIII6I=; b=QaD8/fJcb9iLYEHiy6IVimMw1za4lFwclf+k05eBWxy7DCWwTVf7VZ/zUFSiMRXCiSrI wA1fxz37vnIFOOUDIrPHUFpkJqYRpxPL0T0DHGiWEQU9MzXuJUlS7mTu477qUynb6beQ vsEg7zeRa6aWFlVITFpExcZHWBDaMBFvTi8= Received: from mail.thefacebook.com ([163.114.132.120]) by m0001303.ppops.net with ESMTP id 3assek2pqg-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 31 Aug 2021 17:35:31 -0700 Received: from intmgw002.06.ash9.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:21d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 31 Aug 2021 17:35:29 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 66B2BF5868EB; Tue, 31 Aug 2021 17:35:23 -0700 (PDT) From: Song Liu To: , CC: , , , , , Song Liu Subject: [PATCH v4 bpf-next 1/3] perf: enable branch record for software events Date: Tue, 31 Aug 2021 17:35:15 -0700 Message-ID: <20210901003517.3953145-2-songliubraving@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210901003517.3953145-1-songliubraving@fb.com> References: <20210901003517.3953145-1-songliubraving@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-FB-Source: Intern X-Proofpoint-ORIG-GUID: _Nf7iES7ZJWa3axybXqHj-7vnvAq6VKI X-Proofpoint-GUID: _Nf7iES7ZJWa3axybXqHj-7vnvAq6VKI X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-31_10:2021-08-31,2021-08-31 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 clxscore=1015 suspectscore=0 impostorscore=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 mlxlogscore=999 spamscore=0 phishscore=0 malwarescore=0 mlxscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2109010001 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net The typical way to access branch record (e.g. Intel LBR) is via hardware perf_event. For CPUs with FREEZE_LBRS_ON_PMI support, PMI could capture reliable LBR. On the other hand, LBR could also be useful in non-PMI scenario. For example, in kretprobe or bpf fexit program, LBR could provide a lot of information on what happened with the function. Add API to use branch record for software use. Note that, when the software event triggers, it is necessary to stop the branch record hardware asap. Therefore, static_call is used to remove some branch instructions in this process. Signed-off-by: Song Liu --- arch/x86/events/intel/core.c | 26 +++++++++++++++++++++++--- arch/x86/events/intel/ds.c | 8 -------- arch/x86/events/perf_event.h | 10 ++++++++-- include/linux/perf_event.h | 26 ++++++++++++++++++++++++++ kernel/events/core.c | 2 ++ 5 files changed, 59 insertions(+), 13 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index ac6fd2dabf6a2..fe9bec93eb53b 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -2143,7 +2143,7 @@ static __initconst const u64 knl_hw_cache_extra_regs * However, there are some cases which may change PEBS status, e.g. PMI * throttle. The PEBS_ENABLE should be updated where the status changes. */ -static void __intel_pmu_disable_all(void) +static __always_inline void __intel_pmu_disable_all(void) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); @@ -2153,7 +2153,7 @@ static void __intel_pmu_disable_all(void) intel_pmu_disable_bts(); } -static void intel_pmu_disable_all(void) +static __always_inline void intel_pmu_disable_all(void) { __intel_pmu_disable_all(); intel_pmu_pebs_disable_all(); @@ -2186,6 +2186,20 @@ static void intel_pmu_enable_all(int added) __intel_pmu_enable_all(added, false); } +static int +intel_pmu_snapshot_branch_stack(struct perf_branch_snapshot *br_snapshot) +{ + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + + intel_pmu_disable_all(); + intel_pmu_lbr_read(); + memcpy(br_snapshot->entries, cpuc->lbr_entries, + sizeof(struct perf_branch_entry) * x86_pmu.lbr_nr); + br_snapshot->nr = x86_pmu.lbr_nr; + intel_pmu_enable_all(0); + return 0; +} + /* * Workaround for: * Intel Errata AAK100 (model 26) @@ -6283,9 +6297,15 @@ __init int intel_pmu_init(void) x86_pmu.lbr_nr = 0; } - if (x86_pmu.lbr_nr) + if (x86_pmu.lbr_nr) { pr_cont("%d-deep LBR, ", x86_pmu.lbr_nr); + /* only support branch_stack snapshot for perfmon >= v2 */ + if (x86_pmu.disable_all == intel_pmu_disable_all) + static_call_update(perf_snapshot_branch_stack, + intel_pmu_snapshot_branch_stack); + } + intel_pmu_check_extra_regs(x86_pmu.extra_regs); /* Support full width counters using alternative MSR range */ diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index 8647713276a73..8a832986578a9 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1296,14 +1296,6 @@ void intel_pmu_pebs_enable_all(void) wrmsrl(MSR_IA32_PEBS_ENABLE, cpuc->pebs_enabled); } -void intel_pmu_pebs_disable_all(void) -{ - struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); - - if (cpuc->pebs_enabled) - wrmsrl(MSR_IA32_PEBS_ENABLE, 0); -} - static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index e3ac05c97b5e5..171abbb359fe5 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -1240,6 +1240,14 @@ static inline bool intel_pmu_has_bts(struct perf_event *event) return intel_pmu_has_bts_period(event, hwc->sample_period); } +static __always_inline void intel_pmu_pebs_disable_all(void) +{ + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + + if (cpuc->pebs_enabled) + wrmsrl(MSR_IA32_PEBS_ENABLE, 0); +} + int intel_pmu_save_and_restart(struct perf_event *event); struct event_constraint * @@ -1314,8 +1322,6 @@ void intel_pmu_pebs_disable(struct perf_event *event); void intel_pmu_pebs_enable_all(void); -void intel_pmu_pebs_disable_all(void); - void intel_pmu_pebs_sched_task(struct perf_event_context *ctx, bool sched_in); void intel_pmu_auto_reload_read(struct perf_event *event); diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index fe156a8170aa3..a368dfd754608 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -57,6 +57,7 @@ struct perf_guest_info_callbacks { #include #include #include +#include #include struct perf_callchain_entry { @@ -1612,4 +1613,29 @@ extern void __weak arch_perf_update_userpage(struct perf_event *event, extern __weak u64 arch_perf_get_page_size(struct mm_struct *mm, unsigned long addr); #endif +/* + * Snapshot branch stack on software events. + * + * Branch stack can be very useful in understanding software events. For + * example, when a long function, e.g. sys_perf_event_open, returns an + * errno, it is not obvious why the function failed. Branch stack could + * provide very helpful information in this type of scenarios. + * + * On software event, it is necessary to stop the hardware branch recorder + * fast. Otherwise, the hardware register/buffer will be flushed with + * entries af the triggering event. Therefore, static call is used to + * stop the hardware recorder. + */ +enum { + PERF_MAX_BRANCH_SNAPSHOT = 32, +}; + +struct perf_branch_snapshot { + unsigned int nr; + struct perf_branch_entry entries[PERF_MAX_BRANCH_SNAPSHOT]; +}; + +typedef int (perf_snapshot_branch_stack_t)(struct perf_branch_snapshot *); +DECLARE_STATIC_CALL(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t); + #endif /* _LINUX_PERF_EVENT_H */ diff --git a/kernel/events/core.c b/kernel/events/core.c index 011cc5069b7ba..d32a3cf37eb90 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -13437,3 +13437,5 @@ struct cgroup_subsys perf_event_cgrp_subsys = { .threaded = true, }; #endif /* CONFIG_CGROUP_PERF */ + +DEFINE_STATIC_CALL_RET0(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t); From patchwork Wed Sep 1 00:35:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12468011 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, URIBL_BLOCKED,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 EB59CC4320A for ; Wed, 1 Sep 2021 00:35:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0D2061041 for ; Wed, 1 Sep 2021 00:35:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230062AbhIAAgd (ORCPT ); Tue, 31 Aug 2021 20:36:33 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:12048 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241458AbhIAAgb (ORCPT ); Tue, 31 Aug 2021 20:36:31 -0400 Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 1810ShFG011771 for ; Tue, 31 Aug 2021 17:35:36 -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=wAnRhnQHsBGWS30dkE41tRfVrCpRIrwrA3URonrxIPY=; b=eDls+kmj5k/ZqNbOzphaDriia8Rg2WcjO5ly7vXvxvJE2fHf/yOdlBQxbvqiURnZwYAG /Dyr2trV3/1QpfNNZSHawgui/FWBtXSj9Qbuubneh5Ajb49uXVOTMbcd1aQa/tuD9mRN pZkd441w5n+CG5i0zd7M3yFCeue5aeq8QK4= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 3arykq3tjr-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 31 Aug 2021 17:35:35 -0700 Received: from intmgw001.37.frc1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::e) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.14; Tue, 31 Aug 2021 17:35:33 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 7041FF586921; Tue, 31 Aug 2021 17:35:26 -0700 (PDT) From: Song Liu To: , CC: , , , , , Song Liu Subject: [PATCH v4 bpf-next 2/3] bpf: introduce helper bpf_get_branch_snapshot Date: Tue, 31 Aug 2021 17:35:16 -0700 Message-ID: <20210901003517.3953145-3-songliubraving@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210901003517.3953145-1-songliubraving@fb.com> References: <20210901003517.3953145-1-songliubraving@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-FB-Source: Intern X-Proofpoint-GUID: ZwJdycc0MsNgz679farVLcuAGaI2tTSn X-Proofpoint-ORIG-GUID: ZwJdycc0MsNgz679farVLcuAGaI2tTSn X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-31_10:2021-08-31,2021-08-31 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 impostorscore=0 lowpriorityscore=0 adultscore=0 malwarescore=0 priorityscore=1501 mlxscore=0 phishscore=0 bulkscore=0 mlxlogscore=999 spamscore=0 clxscore=1015 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2109010001 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. Signed-off-by: Song Liu --- include/uapi/linux/bpf.h | 22 +++++++++++++++++++ kernel/bpf/trampoline.c | 3 ++- kernel/trace/bpf_trace.c | 40 ++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 22 +++++++++++++++++++ 4 files changed, 86 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), \ /* */ /* 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..a8ec3634a3329 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1017,6 +1017,44 @@ static const struct bpf_func_proto bpf_get_attach_cookie_proto_pe = { .arg1_type = ARG_PTR_TO_CTX, }; +static DEFINE_PER_CPU(struct perf_branch_snapshot, bpf_perf_branch_snapshot); + +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 to_copy; + + if (unlikely(flags)) + return -EINVAL; + + if (!buf || (size % br_entry_size != 0)) + return -EINVAL; + + static_call(perf_snapshot_branch_stack)(this_cpu_ptr(&bpf_perf_branch_snapshot)); + + if (this_cpu_ptr(&bpf_perf_branch_snapshot)->nr == 0) + return -ENOENT; + + to_copy = this_cpu_ptr(&bpf_perf_branch_snapshot)->nr * + sizeof(struct perf_branch_entry); + to_copy = min_t(u32, size, to_copy); + memcpy(buf, this_cpu_ptr(&bpf_perf_branch_snapshot)->entries, to_copy); + + return to_copy; +#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 +1170,8 @@ 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..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), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper From patchwork Wed Sep 1 00:35:17 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12468009 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, URIBL_BLOCKED,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 57A82C41537 for ; Wed, 1 Sep 2021 00:35:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 363C761075 for ; Wed, 1 Sep 2021 00:35:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241453AbhIAAga (ORCPT ); Tue, 31 Aug 2021 20:36:30 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:61680 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230062AbhIAAg3 (ORCPT ); Tue, 31 Aug 2021 20:36:29 -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 1810S4t7028187 for ; Tue, 31 Aug 2021 17:35:33 -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=ji+vwwd4eLTbcJw2c2j868X0v2GjIrzS21oBKXZzeeQ=; b=bb85rmRpAeoxyE3Rdeywwz4bzb8c/1q2U5gZYMLxTx8U4t50tdIOCAjhTbYXtpRhcRds wJA8GRdMHBHe+lpID6Ez+pFp5vl4403jrC+IofdJ8yN4frlJ1M7oab/Tk/FZ7U4CmdyP zztfcUNXYmi96fIGB2ZLs4Hhi1Ik5G1X/nA= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 3aryqsbt2s-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 31 Aug 2021 17:35:33 -0700 Received: from intmgw001.05.ash9.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 15.1.2308.14; Tue, 31 Aug 2021 17:35:32 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 305F2F58692A; Tue, 31 Aug 2021 17:35:29 -0700 (PDT) From: Song Liu To: , CC: , , , , , Song Liu Subject: [PATCH v4 bpf-next 3/3] selftests/bpf: add test for bpf_get_branch_snapshot Date: Tue, 31 Aug 2021 17:35:17 -0700 Message-ID: <20210901003517.3953145-4-songliubraving@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210901003517.3953145-1-songliubraving@fb.com> References: <20210901003517.3953145-1-songliubraving@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-FB-Source: Intern X-Proofpoint-GUID: 7w6s5v2cUE08krQbUIqKPD2aGshahgud X-Proofpoint-ORIG-GUID: 7w6s5v2cUE08krQbUIqKPD2aGshahgud X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-31_10:2021-08-31,2021-08-31 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 impostorscore=0 priorityscore=1501 adultscore=0 phishscore=0 spamscore=0 mlxscore=0 bulkscore=0 clxscore=1015 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2109010001 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This test uses bpf_get_branch_snapshot from a fexit program. The test uses a target function (bpf_testmod_loop_test) and compares the record against kallsyms. If there isn't enough record matching kallsyms, the test fails. Signed-off-by: Song Liu Acked-by: Andrii Nakryiko --- .../selftests/bpf/bpf_testmod/bpf_testmod.c | 14 ++- .../bpf/prog_tests/get_branch_snapshot.c | 101 ++++++++++++++++++ .../selftests/bpf/progs/get_branch_snapshot.c | 44 ++++++++ tools/testing/selftests/bpf/trace_helpers.c | 37 +++++++ tools/testing/selftests/bpf/trace_helpers.h | 5 + 5 files changed, 200 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c create mode 100644 tools/testing/selftests/bpf/progs/get_branch_snapshot.c diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index 141d8da687d21..19635e57ff21a 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -13,6 +13,18 @@ DEFINE_PER_CPU(int, bpf_testmod_ksym_percpu) = 123; +noinline int bpf_testmod_loop_test(int n) +{ + int i, sum = 0; + + /* the primary goal of this test is to test LBR. Create a lot of + * branches in the function, so we can catch it easily. + */ + for (i = 0; i < n; i++) + sum += i; + return sum; +} + noinline ssize_t bpf_testmod_test_read(struct file *file, struct kobject *kobj, struct bin_attribute *bin_attr, @@ -24,6 +36,7 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj, .len = len, }; + bpf_testmod_loop_test(101); trace_bpf_testmod_test_read(current, &ctx); return -EIO; /* always fail */ @@ -71,4 +84,3 @@ module_exit(bpf_testmod_exit); MODULE_AUTHOR("Andrii Nakryiko"); MODULE_DESCRIPTION("BPF selftests module"); MODULE_LICENSE("Dual BSD/GPL"); - diff --git a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c new file mode 100644 index 0000000000000..03ffa5cdf9b09 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c @@ -0,0 +1,101 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Facebook */ +#include +#include "get_branch_snapshot.skel.h" + +static int *pfd_array; +static int cpu_cnt; + +static int create_perf_events(void) +{ + struct perf_event_attr attr = {0}; + int cpu; + + /* create perf event */ + attr.size = sizeof(attr); + attr.type = PERF_TYPE_RAW; + attr.config = 0x1b00; + attr.sample_type = PERF_SAMPLE_BRANCH_STACK; + attr.branch_sample_type = PERF_SAMPLE_BRANCH_KERNEL | + PERF_SAMPLE_BRANCH_USER | PERF_SAMPLE_BRANCH_ANY; + + cpu_cnt = libbpf_num_possible_cpus(); + pfd_array = malloc(sizeof(int) * cpu_cnt); + if (!pfd_array) { + cpu_cnt = 0; + return 1; + } + + for (cpu = 0; cpu < cpu_cnt; cpu++) { + pfd_array[cpu] = syscall(__NR_perf_event_open, &attr, + -1, cpu, -1, PERF_FLAG_FD_CLOEXEC); + if (pfd_array[cpu] < 0) + break; + } + + return cpu == 0; +} + +static void close_perf_events(void) +{ + int cpu = 0; + int fd; + + while (cpu++ < cpu_cnt) { + fd = pfd_array[cpu]; + if (fd < 0) + break; + close(fd); + } + free(pfd_array); +} + +void test_get_branch_snapshot(void) +{ + struct get_branch_snapshot *skel = NULL; + int err; + + if (create_perf_events()) { + test__skip(); /* system doesn't support LBR */ + goto cleanup; + } + + skel = get_branch_snapshot__open_and_load(); + if (!ASSERT_OK_PTR(skel, "get_branch_snapshot__open_and_load")) + goto cleanup; + + err = kallsyms_find("bpf_testmod_loop_test", &skel->bss->address_low); + if (!ASSERT_OK(err, "kallsyms_find")) + goto cleanup; + + err = kallsyms_find_next("bpf_testmod_loop_test", &skel->bss->address_high); + if (!ASSERT_OK(err, "kallsyms_find_next")) + goto cleanup; + + err = get_branch_snapshot__attach(skel); + if (!ASSERT_OK(err, "get_branch_snapshot__attach")) + goto cleanup; + + /* trigger the program */ + system("cat /sys/kernel/bpf_testmod > /dev/null 2>& 1"); + + if (skel->bss->total_entries < 16) { + /* too few entries for the hit/waste test */ + test__skip(); + goto cleanup; + } + + ASSERT_GT(skel->bss->test1_hits, 1, "find_looptest_in_lbr"); + + /* Given we stop LBR in software, we will waste a few entries. + * But we should try to waste as few as possible entries. We are at + * about 11 on x86_64 systems. + * Add a check for < 15 so that we get heads-up when something + * changes and wastes too many entries. + */ + ASSERT_LT(skel->bss->wasted_entries, 15, "check_wasted_entries"); + +cleanup: + get_branch_snapshot__destroy(skel); + close_perf_events(); +} diff --git a/tools/testing/selftests/bpf/progs/get_branch_snapshot.c b/tools/testing/selftests/bpf/progs/get_branch_snapshot.c new file mode 100644 index 0000000000000..24a6e7a9c08ac --- /dev/null +++ b/tools/testing/selftests/bpf/progs/get_branch_snapshot.c @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Facebook */ +#include "vmlinux.h" +#include +#include + +char _license[] SEC("license") = "GPL"; + +__u64 test1_hits = 0; +__u64 address_low = 0; +__u64 address_high = 0; +int wasted_entries = 0; +long total_entries = 0; + +struct perf_branch_entry entries[PERF_MAX_BRANCH_SNAPSHOT] = {}; + + +static inline bool in_range(__u64 val) +{ + return (val >= address_low) && (val < address_high); +} + +SEC("fexit/bpf_testmod_loop_test") +int BPF_PROG(test1, int n, int ret) +{ + long i; + + total_entries = bpf_get_branch_snapshot(entries, sizeof(entries), 0); + total_entries /= sizeof(struct perf_branch_entry); + + bpf_printk("total_entries %lu\n", total_entries); + + for (i = 0; i < PERF_MAX_BRANCH_SNAPSHOT; i++) { + if (i >= total_entries) + break; + if (in_range(entries[i].from) && in_range(entries[i].to)) + test1_hits++; + else if (!test1_hits) + wasted_entries++; + bpf_printk("i %d from %llx to %llx", i, entries[i].from, + entries[i].to); + } + return 0; +} diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c index e7a19b04d4eaf..5100a169b72b1 100644 --- a/tools/testing/selftests/bpf/trace_helpers.c +++ b/tools/testing/selftests/bpf/trace_helpers.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include #include @@ -117,6 +118,42 @@ int kallsyms_find(const char *sym, unsigned long long *addr) return err; } +/* find the address of the next symbol of the same type, this can be used + * to determine the end of a function. + */ +int kallsyms_find_next(const char *sym, unsigned long long *addr) +{ + char type, found_type, name[500]; + unsigned long long value; + bool found = false; + int err = 0; + FILE *f; + + f = fopen("/proc/kallsyms", "r"); + if (!f) + return -EINVAL; + + while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) { + /* Different types of symbols in kernel modules are mixed + * in /proc/kallsyms. Only return the next matching type. + * Use tolower() for type so that 'T' matches 't'. + */ + if (found && found_type == tolower(type)) { + *addr = value; + goto out; + } + if (strcmp(name, sym) == 0) { + found = true; + found_type = tolower(type); + } + } + err = -ENOENT; + +out: + fclose(f); + return err; +} + void read_trace_pipe(void) { int trace_fd; diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h index d907b445524d5..bc8ed86105d94 100644 --- a/tools/testing/selftests/bpf/trace_helpers.h +++ b/tools/testing/selftests/bpf/trace_helpers.h @@ -16,6 +16,11 @@ long ksym_get_addr(const char *name); /* open kallsyms and find addresses on the fly, faster than load + search. */ int kallsyms_find(const char *sym, unsigned long long *addr); +/* find the address of the next symbol, this can be used to determine the + * end of a function + */ +int kallsyms_find_next(const char *sym, unsigned long long *addr); + void read_trace_pipe(void); ssize_t get_uprobe_offset(const void *addr, ssize_t base);