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bh=70ElBaIlNpfinFqgBHCRVniknEMUVCubYfZ4SWyaVvw=; b=RVjSLACltQq6wrQy35o/smbrYKpA6SkJx0XmU8sRUKSdZfFnmYj74KGYG2rcPFyqsH 5xTI3J52PUDnyewze8vA8k8kg/k9SOB4d1EFqnrJWrnhvJj4quCYNKgrqM6vFCgvlHQy veJtRv+9+lXmCfsGUNy7TXJFJ/5yZIUm+V4rPbosBfwzz5SboHPP73w93i/2CpzFUvtw ahCT8s6jNpLGAnCqUiVJ6zHYKisTg9wA3sRY1KQ9TU6zxkvxEO8vPK83REQeoUty0dGL F9YwhBvOZu5TacgRPCJgczgUb5gfrOHyvQZPxK+vhxBJkGDRMHTKxZC4qowFVRdycLTE +TxA== X-Gm-Message-State: APjAAAUVyjBDiR0/6QO8PRQQfAzax73uC9TE9ednzX25ggZf3fnkh+we MHIhHn45tossUJEuY6ZRyVPG2XHR7W6RnoPYChRplw3yiBaKpg== X-Google-Smtp-Source: APXvYqwUaxh5ZgoMa40oIlCreo/G9LQi4kL/JKbXH9iA3olPbfcP3crIMbboHvxHf93EZt+rqC4IEhV1RIYi+4Tub7A= X-Received: by 2002:ac8:2d56:: with SMTP id o22mr1952555qta.171.1561525924771; Tue, 25 Jun 2019 22:12:04 -0700 (PDT) MIME-Version: 1.0 References: <20190625232601.3227055-1-andriin@fb.com> <20190625232601.3227055-3-andriin@fb.com> In-Reply-To: <20190625232601.3227055-3-andriin@fb.com> From: Andrii Nakryiko Date: Tue, 25 Jun 2019 22:11:53 -0700 Message-ID: Subject: Re: [PATCH bpf-next 2/2] selftests/bpf: test perf buffer API To: Andrii Nakryiko Cc: Alexei Starovoitov , Daniel Borkmann , bpf , Networking , Kernel Team Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Jun 25, 2019 at 4:26 PM Andrii Nakryiko wrote: > > Add test verifying perf buffer API functionality. > > Signed-off-by: Andrii Nakryiko > --- > .../selftests/bpf/prog_tests/perf_buffer.c | 86 +++++++++++++++++++ > .../selftests/bpf/progs/test_perf_buffer.c | 31 +++++++ > 2 files changed, 117 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_buffer.c > create mode 100644 tools/testing/selftests/bpf/progs/test_perf_buffer.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/perf_buffer.c b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c > new file mode 100644 > index 000000000000..3ba3e26141ac > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c > @@ -0,0 +1,86 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#define _GNU_SOURCE > +#include > +#include > +#include > +#include > + > +static void on_sample(void *ctx, void *data, __u32 size) > +{ > + cpu_set_t *cpu_seen = ctx; > + int cpu = *(int *)data; > + > + CPU_SET(cpu, cpu_seen); > +} > + > +void test_perf_buffer(void) > +{ > + int err, prog_fd, prog_pfd, nr_cpus, i, duration = 0; > + const char *prog_name = "kprobe/sys_nanosleep"; > + const char *file = "./test_perf_buffer.o"; > + struct bpf_map *perf_buf_map; > + cpu_set_t cpu_set, cpu_seen; > + struct bpf_program *prog; > + struct bpf_object *obj; > + struct perf_buffer *pb; > + > + nr_cpus = libbpf_num_possible_cpus(); > + if (CHECK(nr_cpus < 0, "nr_cpus", "err %d\n", nr_cpus)) > + return; > + > + /* load program */ > + err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd); > + if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno)) > + return; > + > + prog = bpf_object__find_program_by_title(obj, prog_name); > + if (CHECK(!prog, "find_probe", "prog '%s' not found\n", prog_name)) > + goto out_close; > + > + /* load map */ > + perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map"); > + if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n")) > + goto out_close; > + > + /* attach kprobe */ > + prog_pfd = bpf_program__attach_kprobe(prog, false /* retprobe */, > + "sys_nanosleep"); > + if (CHECK(prog_pfd < 0, "attach_kprobe", "err %d\n", prog_pfd)) > + goto out_close; > + > + /* set up perf buffer */ > + pb = perf_buffer__new(perf_buf_map, 1, on_sample, NULL, &cpu_seen); > + if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb))) > + goto out_detach; > + > + /* trigger kprobe on every CPU */ > + CPU_ZERO(&cpu_seen); > + for (i = 0; i < nr_cpus; i++) { > + CPU_ZERO(&cpu_set); > + CPU_SET(i, &cpu_set); > + > + err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), > + &cpu_set); > + if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n", > + i, err)) > + goto out_detach; > + > + usleep(1); > + } > + > + /* read perf buffer */ > + err = perf_buffer__poll(pb, 100); > + if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err)) > + goto out_free_pb; > + > + if (CHECK(CPU_COUNT(&cpu_seen) != nr_cpus, "seen_cpu_cnt", > + "expect %d, seen %d\n", nr_cpus, CPU_COUNT(&cpu_seen))) > + goto out_free_pb; > + > +out_free_pb: > + perf_buffer__free(pb); > +out_detach: > + libbpf_perf_event_disable_and_close(prog_pfd); > +out_close: > + bpf_object__close(obj); > +} > diff --git a/tools/testing/selftests/bpf/progs/test_perf_buffer.c b/tools/testing/selftests/bpf/progs/test_perf_buffer.c > new file mode 100644 > index 000000000000..ba961f608fd5 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/test_perf_buffer.c > @@ -0,0 +1,31 @@ > +// SPDX-License-Identifier: GPL-2.0 > +// Copyright (c) 2019 Facebook > + > +#include > +#include > +#include "bpf_helpers.h" > + > +struct { > + int type; > + int key_size; > + int value_size; > + int max_entries; > +} perf_buf_map SEC(".maps") = { > + .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY, > + .key_size = sizeof(int), > + .value_size = sizeof(int), > + .max_entries = 56, Oh, this is not right, "works for me" only :). I've been meaning to actually have another change to handle not specified max_entries (or equivalently, max_entries == 0) to mean "all possible CPUs" for BPF_MAP_TYPE_PERF_EVENT_ARRAY. Will produce v2 with that change. > +}; > + > +SEC("kprobe/sys_nanosleep") > +int handle_sys_nanosleep_entry(struct pt_regs *ctx) > +{ > + int cpu = bpf_get_smp_processor_id(); > + > + bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU, > + &cpu, sizeof(cpu)); > + return 0; > +} > + > +char _license[] SEC("license") = "GPL"; > +__u32 _version SEC("version") = 1; > -- > 2.17.1 >