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Date: Thu, 23 Jan 2020 13:23:12 -0800
From: Daniel Xu <dxu@...uu.xyz>
To: bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
songliubraving@...com, yhs@...com, andriin@...com
Cc: Daniel Xu <dxu@...uu.xyz>, linux-kernel@...r.kernel.org,
kernel-team@...com, peterz@...radead.org, mingo@...hat.com,
acme@...nel.org
Subject: [PATCH v3 bpf-next 3/3] selftests/bpf: add bpf_perf_prog_read_branches() selftest
Signed-off-by: Daniel Xu <dxu@...uu.xyz>
---
.../selftests/bpf/prog_tests/perf_branches.c | 106 ++++++++++++++++++
.../selftests/bpf/progs/test_perf_branches.c | 39 +++++++
2 files changed, 145 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_branches.c
create mode 100644 tools/testing/selftests/bpf/progs/test_perf_branches.c
diff --git a/tools/testing/selftests/bpf/prog_tests/perf_branches.c b/tools/testing/selftests/bpf/prog_tests/perf_branches.c
new file mode 100644
index 000000000000..f8d7356a6507
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/perf_branches.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <pthread.h>
+#include <sched.h>
+#include <sys/socket.h>
+#include <test_progs.h>
+#include "bpf/libbpf_internal.h"
+
+static void on_sample(void *ctx, int cpu, void *data, __u32 size)
+{
+ int pbe_size = sizeof(struct perf_branch_entry);
+ int ret = *(int *)data, duration = 0;
+
+ // It's hard to validate the contents of the branch entries b/c it
+ // would require some kind of disassembler and also encoding the
+ // valid jump instructions for supported architectures. So just check
+ // the easy stuff for now.
+ CHECK(ret < 0, "read_branches", "err %d\n", ret);
+ CHECK(ret % pbe_size != 0, "read_branches",
+ "bytes written=%d not multiple of struct size=%d\n",
+ ret, pbe_size);
+
+ *(int *)ctx = 1;
+}
+
+void test_perf_branches(void)
+{
+ int err, prog_fd, i, pfd = -1, duration = 0, ok = 0;
+ const char *file = "./test_perf_branches.o";
+ const char *prog_name = "perf_event";
+ struct perf_buffer_opts pb_opts = {};
+ struct perf_event_attr attr = {};
+ struct bpf_map *perf_buf_map;
+ struct bpf_program *prog;
+ struct bpf_object *obj;
+ struct perf_buffer *pb;
+ struct bpf_link *link;
+ volatile int j = 0;
+ cpu_set_t cpu_set;
+
+ /* load program */
+ err = bpf_prog_load(file, BPF_PROG_TYPE_PERF_EVENT, &obj, &prog_fd);
+ if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno)) {
+ obj = NULL;
+ goto out_close;
+ }
+
+ 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;
+
+ /* create perf event */
+ attr.size = sizeof(attr);
+ attr.type = PERF_TYPE_HARDWARE;
+ attr.config = PERF_COUNT_HW_CPU_CYCLES;
+ attr.freq = 1;
+ attr.sample_freq = 4000;
+ attr.sample_type = PERF_SAMPLE_BRANCH_STACK;
+ attr.branch_sample_type = PERF_SAMPLE_BRANCH_USER | PERF_SAMPLE_BRANCH_ANY;
+ pfd = syscall(__NR_perf_event_open, &attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
+ if (CHECK(pfd < 0, "perf_event_open", "err %d\n", pfd))
+ goto out_close;
+
+ /* attach perf_event */
+ link = bpf_program__attach_perf_event(prog, pfd);
+ if (CHECK(IS_ERR(link), "attach_perf_event", "err %ld\n", PTR_ERR(link)))
+ goto out_close_perf;
+
+ /* set up perf buffer */
+ pb_opts.sample_cb = on_sample;
+ pb_opts.ctx = &ok;
+ pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
+ if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
+ goto out_detach;
+
+ /* generate some branches on cpu 0 */
+ CPU_ZERO(&cpu_set);
+ CPU_SET(0, &cpu_set);
+ err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), &cpu_set);
+ if (err && CHECK(err, "set_affinity", "cpu #0, err %d\n", err))
+ goto out_free_pb;
+ for (i = 0; i < 1000000; ++i)
+ ++j;
+
+ /* read perf buffer */
+ err = perf_buffer__poll(pb, 500);
+ if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
+ goto out_free_pb;
+
+ if (CHECK(!ok, "ok", "not ok\n"))
+ goto out_free_pb;
+
+out_free_pb:
+ perf_buffer__free(pb);
+out_detach:
+ bpf_link__destroy(link);
+out_close_perf:
+ close(pfd);
+out_close:
+ bpf_object__close(obj);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_perf_branches.c b/tools/testing/selftests/bpf/progs/test_perf_branches.c
new file mode 100644
index 000000000000..d818079c7778
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_perf_branches.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <linux/ptrace.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_trace_helpers.h"
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(int));
+ __uint(value_size, sizeof(int));
+} perf_buf_map SEC(".maps");
+
+struct fake_perf_branch_entry {
+ __u64 _a;
+ __u64 _b;
+ __u64 _c;
+};
+
+SEC("perf_event")
+int perf_branches(void *ctx)
+{
+ int ret;
+ struct fake_perf_branch_entry entries[4];
+
+ ret = bpf_perf_prog_read_branches(ctx,
+ entries,
+ sizeof(entries));
+ /* ignore spurious events */
+ if (!ret)
+ return 1;
+
+ bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
+ &ret, sizeof(ret));
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.21.1
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