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);