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=-13.1 required=3.0 tests=BAYES_00,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, 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 132A0C433E1 for ; Wed, 15 Jul 2020 05:29:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D89522068F for ; Wed, 15 Jul 2020 05:29:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="dx6TtZ6C" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728453AbgGOF3K (ORCPT ); Wed, 15 Jul 2020 01:29:10 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:48876 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728441AbgGOF3K (ORCPT ); Wed, 15 Jul 2020 01:29:10 -0400 Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 06F5SEU6018689 for ; Tue, 14 Jul 2020 22:29:08 -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=XSMkumciHLDEqkxs1TfDOcyUVuWIsOhqryFAIq0eY8Q=; b=dx6TtZ6CyzDqZ0D9nVxKuoOJ/XVFn8MagsmcldzYbVSjHOC7gvGxSjaAlIqlLFsUi6Eg 4CwrfdfeTv0tk3zYwu1eNZ4xti9R4ZN6OEV9A0aJn24JoOWwgUbo4rDeQxj/f4g0MJ/l HY84ewyaeOKXyBRJCsDA6qCx/JCPJ8bYyYY= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 327wdrp17s-10 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 14 Jul 2020 22:29:08 -0700 Received: from intmgw003.03.ash8.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 14 Jul 2020 22:29:04 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id E552A62E52E0; Tue, 14 Jul 2020 22:26:07 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig006.ftw2.facebook.com To: , , CC: , , , , , , , Song Liu Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH v2 bpf-next 1/2] bpf: separate bpf_get_[stack|stackid] for perf events BPF Date: Tue, 14 Jul 2020 22:26:00 -0700 Message-ID: <20200715052601.2404533-2-songliubraving@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200715052601.2404533-1-songliubraving@fb.com> References: <20200715052601.2404533-1-songliubraving@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-07-15_02:2020-07-15,2020-07-15 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 mlxscore=0 malwarescore=0 phishscore=0 clxscore=1015 impostorscore=0 suspectscore=0 adultscore=0 spamscore=0 lowpriorityscore=0 priorityscore=1501 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007150046 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Calling get_perf_callchain() on perf_events from PEBS entries may cause unwinder errors. To fix this issue, the callchain is fetched early. Such perf_events are marked with __PERF_SAMPLE_CALLCHAIN_EARLY. Similarly, calling bpf_get_[stack|stackid] on perf_events from PEBS may also cause unwinder errors. To fix this, add separate version of these two helpers, bpf_get_[stack|stackid]_pe. These two hepers use callchain i= n bpf_perf_event_data_kern->data->callchain. Signed-off-by: Song Liu --- include/linux/bpf.h | 2 + kernel/bpf/stackmap.c | 204 +++++++++++++++++++++++++++++++++++---- kernel/trace/bpf_trace.c | 4 +- 3 files changed, 190 insertions(+), 20 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c67c88ad35f85..bfc7a283c0f93 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1637,6 +1637,8 @@ extern const struct bpf_func_proto bpf_get_current_= comm_proto; extern const struct bpf_func_proto bpf_get_stackid_proto; extern const struct bpf_func_proto bpf_get_stack_proto; extern const struct bpf_func_proto bpf_get_task_stack_proto; +extern const struct bpf_func_proto bpf_get_stackid_proto_pe; +extern const struct bpf_func_proto bpf_get_stack_proto_pe; extern const struct bpf_func_proto bpf_sock_map_update_proto; extern const struct bpf_func_proto bpf_sock_hash_update_proto; extern const struct bpf_func_proto bpf_get_current_cgroup_id_proto; diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 48d8e739975fa..0587d4ddb06ce 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -4,6 +4,7 @@ #include #include #include +#include #include #include #include @@ -387,11 +388,10 @@ get_callchain_entry_for_task(struct task_struct *ta= sk, u32 init_nr) #endif } =20 -BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, ma= p, - u64, flags) +static long __bpf_get_stackid(struct bpf_map *map, + struct perf_callchain_entry *trace, u64 flags) { struct bpf_stack_map *smap =3D container_of(map, struct bpf_stack_map, = map); - struct perf_callchain_entry *trace; struct stack_map_bucket *bucket, *new_bucket, *old_bucket; u32 max_depth =3D map->value_size / stack_map_data_size(map); /* stack_map_alloc() checks that max_depth <=3D sysctl_perf_event_max_s= tack */ @@ -399,21 +399,9 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, = struct bpf_map *, map, u32 skip =3D flags & BPF_F_SKIP_FIELD_MASK; u32 hash, id, trace_nr, trace_len; bool user =3D flags & BPF_F_USER_STACK; - bool kernel =3D !user; u64 *ips; bool hash_matches; =20 - if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | - BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) - return -EINVAL; - - trace =3D get_perf_callchain(regs, init_nr, kernel, user, - sysctl_perf_event_max_stack, false, false); - - if (unlikely(!trace)) - /* couldn't fetch the stack trace */ - return -EFAULT; - /* get_perf_callchain() guarantees that trace->nr >=3D init_nr * and trace-nr <=3D sysctl_perf_event_max_stack, so trace_nr <=3D max_= depth */ @@ -478,6 +466,30 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, = struct bpf_map *, map, return id; } =20 +BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, ma= p, + u64, flags) +{ + u32 max_depth =3D map->value_size / stack_map_data_size(map); + /* stack_map_alloc() checks that max_depth <=3D sysctl_perf_event_max_s= tack */ + u32 init_nr =3D sysctl_perf_event_max_stack - max_depth; + bool user =3D flags & BPF_F_USER_STACK; + struct perf_callchain_entry *trace; + bool kernel =3D !user; + + if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | + BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) + return -EINVAL; + + trace =3D get_perf_callchain(regs, init_nr, kernel, user, + sysctl_perf_event_max_stack, false, false); + + if (unlikely(!trace)) + /* couldn't fetch the stack trace */ + return -EFAULT; + + return __bpf_get_stackid(map, trace, flags); +} + const struct bpf_func_proto bpf_get_stackid_proto =3D { .func =3D bpf_get_stackid, .gpl_only =3D true, @@ -487,7 +499,87 @@ const struct bpf_func_proto bpf_get_stackid_proto =3D= { .arg3_type =3D ARG_ANYTHING, }; =20 +static __u64 count_kernel_ip(struct perf_callchain_entry *trace) +{ + __u64 nr_kernel =3D 0; + + while (nr_kernel < trace->nr) { + if (trace->ip[nr_kernel] =3D=3D PERF_CONTEXT_USER) + break; + nr_kernel++; + } + return nr_kernel; +} + +BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, + struct bpf_map *, map, u64, flags) +{ + struct perf_event *event =3D ctx->event; + struct perf_callchain_entry *trace; + bool has_kernel, has_user; + bool kernel, user; + + /* perf_sample_data doesn't have callchain, use bpf_get_stackid */ + if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY)) + return bpf_get_stackid((unsigned long)(ctx->regs), + (unsigned long) map, flags, 0, 0); + + if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | + BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) + return -EINVAL; + + user =3D flags & BPF_F_USER_STACK; + kernel =3D !user; + + has_kernel =3D !event->attr.exclude_callchain_kernel; + has_user =3D !event->attr.exclude_callchain_user; + + if ((kernel && !has_kernel) || (user && !has_user)) + return -EINVAL; + + trace =3D ctx->data->callchain; + if (!trace || (!has_kernel && !has_user)) + return -EFAULT; + + if (has_kernel && has_user) { + __u64 nr_kernel =3D count_kernel_ip(trace); + int ret; + + if (kernel) { + __u64 nr =3D trace->nr; + + trace->nr =3D nr_kernel; + ret =3D __bpf_get_stackid(map, trace, flags); + + /* restore nr */ + trace->nr =3D nr; + } else { /* user */ + u64 skip =3D flags & BPF_F_SKIP_FIELD_MASK; + + skip +=3D nr_kernel; + if (skip > ~BPF_F_SKIP_FIELD_MASK) + return -EFAULT; + + flags =3D (flags & ~BPF_F_SKIP_FIELD_MASK) | + (skip & BPF_F_SKIP_FIELD_MASK); + ret =3D __bpf_get_stackid(map, trace, flags); + } + return ret; + } + return __bpf_get_stackid(map, trace, flags); +} + +const struct bpf_func_proto bpf_get_stackid_proto_pe =3D { + .func =3D bpf_get_stackid_pe, + .gpl_only =3D false, + .ret_type =3D RET_INTEGER, + .arg1_type =3D ARG_PTR_TO_CTX, + .arg2_type =3D ARG_CONST_MAP_PTR, + .arg3_type =3D ARG_ANYTHING, +}; + static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *ta= sk, + struct perf_callchain_entry *trace_in, void *buf, u32 size, u64 flags) { u32 init_nr, trace_nr, copy_len, elem_size, num_elem; @@ -520,7 +612,9 @@ static long __bpf_get_stack(struct pt_regs *regs, str= uct task_struct *task, else init_nr =3D sysctl_perf_event_max_stack - num_elem; =20 - if (kernel && task) + if (trace_in) + trace =3D trace_in; + else if (kernel && task) trace =3D get_callchain_entry_for_task(task, init_nr); else trace =3D get_perf_callchain(regs, init_nr, kernel, user, @@ -556,7 +650,7 @@ static long __bpf_get_stack(struct pt_regs *regs, str= uct task_struct *task, BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size= , u64, flags) { - return __bpf_get_stack(regs, NULL, buf, size, flags); + return __bpf_get_stack(regs, NULL, NULL, buf, size, flags); } =20 const struct bpf_func_proto bpf_get_stack_proto =3D { @@ -574,7 +668,7 @@ BPF_CALL_4(bpf_get_task_stack, struct task_struct *, = task, void *, buf, { struct pt_regs *regs =3D task_pt_regs(task); =20 - return __bpf_get_stack(regs, task, buf, size, flags); + return __bpf_get_stack(regs, task, NULL, buf, size, flags); } =20 BTF_ID_LIST(bpf_get_task_stack_btf_ids) @@ -591,6 +685,80 @@ const struct bpf_func_proto bpf_get_task_stack_proto= =3D { .btf_id =3D bpf_get_task_stack_btf_ids, }; =20 +BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx, + void *, buf, u32, size, u64, flags) +{ + struct perf_event *event =3D ctx->event; + struct perf_callchain_entry *trace; + bool has_kernel, has_user; + bool kernel, user; + int err =3D -EINVAL; + + if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY)) + return __bpf_get_stack(ctx->regs, NULL, NULL, buf, size, flags); + + if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | + BPF_F_USER_BUILD_ID))) + goto clear; + + user =3D flags & BPF_F_USER_STACK; + kernel =3D !user; + + has_kernel =3D !event->attr.exclude_callchain_kernel; + has_user =3D !event->attr.exclude_callchain_user; + + if ((kernel && !has_kernel) || (user && !has_user)) + goto clear; + + err =3D -EFAULT; + trace =3D ctx->data->callchain; + if (!trace || (!has_kernel && !has_user)) + goto clear; + + if (has_kernel && has_user) { + __u64 nr_kernel =3D count_kernel_ip(trace); + int ret; + + if (kernel) { + __u64 nr =3D trace->nr; + + trace->nr =3D nr_kernel; + ret =3D __bpf_get_stack(ctx->regs, NULL, trace, buf, + size, flags); + + /* restore nr */ + trace->nr =3D nr; + } else { /* user */ + u64 skip =3D flags & BPF_F_SKIP_FIELD_MASK; + + skip +=3D nr_kernel; + if (skip > ~BPF_F_SKIP_FIELD_MASK) + goto clear; + + flags =3D (flags & ~BPF_F_SKIP_FIELD_MASK) | + (skip & BPF_F_SKIP_FIELD_MASK); + ret =3D __bpf_get_stack(ctx->regs, NULL, trace, buf, + size, flags); + } + return ret; + } + return __bpf_get_stack(ctx->regs, NULL, trace, buf, size, flags); +clear: + memset(buf, 0, size); + return err; + +} + +const struct bpf_func_proto bpf_get_stack_proto_pe =3D { + .func =3D bpf_get_stack_pe, + .gpl_only =3D true, + .ret_type =3D RET_INTEGER, + .arg1_type =3D ARG_PTR_TO_CTX, + .arg2_type =3D ARG_PTR_TO_UNINIT_MEM, + .arg3_type =3D ARG_CONST_SIZE_OR_ZERO, + .arg4_type =3D ARG_ANYTHING, +}; + /* Called from eBPF program */ static void *stack_map_lookup_elem(struct bpf_map *map, void *key) { diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 3cc0dcb60ca20..cb91ef902cc43 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1411,9 +1411,9 @@ pe_prog_func_proto(enum bpf_func_id func_id, const = struct bpf_prog *prog) case BPF_FUNC_perf_event_output: return &bpf_perf_event_output_proto_tp; case BPF_FUNC_get_stackid: - return &bpf_get_stackid_proto_tp; + return &bpf_get_stackid_proto_pe; case BPF_FUNC_get_stack: - return &bpf_get_stack_proto_tp; + return &bpf_get_stack_proto_pe; case BPF_FUNC_perf_prog_read_value: return &bpf_perf_prog_read_value_proto; case BPF_FUNC_read_branch_records: --=20 2.24.1