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Message-Id: <20200124211705.24759-4-dxu@dxuuu.xyz>
Date: Fri, 24 Jan 2020 13:17:05 -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 v4 bpf-next 3/3] selftests/bpf: add bpf_perf_prog_read_branches() selftest
Add a selftest to test:
* default bpf_perf_prog_read_branches() behavior
* BPF_F_GET_BR_SIZE flag behavior
* using helper to write to stack
* using helper to write to map
Tested by running:
# ./test_progs -t perf_branches
#27 perf_branches:OK
Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: Daniel Xu <dxu@...uu.xyz>
---
.../selftests/bpf/prog_tests/perf_branches.c | 112 ++++++++++++++++++
.../selftests/bpf/progs/test_perf_branches.c | 74 ++++++++++++
2 files changed, 186 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..54a982a6c513
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/perf_branches.c
@@ -0,0 +1,112 @@
+// 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"
+#include "test_perf_branches.skel.h"
+
+struct output {
+ int required_size;
+ int written_stack;
+ int written_map;
+};
+
+static void on_sample(void *ctx, int cpu, void *data, __u32 size)
+{
+ int pbe_size = sizeof(struct perf_branch_entry);
+ int required_size = ((struct output *)data)->required_size;
+ int written_stack = ((struct output *)data)->written_stack;
+ int written_map = ((struct output *)data)->written_map;
+ int 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(required_size <= 0, "read_branches_size", "err %d\n", required_size);
+ CHECK(written_stack < 0, "read_branches_stack", "err %d\n", written_stack);
+ CHECK(written_stack % pbe_size != 0, "read_branches_stack",
+ "stack bytes written=%d not multiple of struct size=%d\n",
+ written_stack, pbe_size);
+ CHECK(written_map < 0, "read_branches_map", "err %d\n", written_map);
+ CHECK(written_map % pbe_size != 0, "read_branches_map",
+ "map bytes written=%d not multiple of struct size=%d\n",
+ written_map, pbe_size);
+ CHECK(written_map < written_stack, "read_branches_size",
+ "written_map=%d < written_stack=%d\n", written_map, written_stack);
+
+ *(int *)ctx = 1;
+}
+
+void test_perf_branches(void)
+{
+ int err, i, pfd = -1, duration = 0, ok = 0;
+ struct perf_buffer_opts pb_opts = {};
+ struct perf_event_attr attr = {};
+ struct perf_buffer *pb;
+ struct bpf_link *link;
+ volatile int j = 0;
+ cpu_set_t cpu_set;
+
+
+ struct test_perf_branches *skel;
+ skel = test_perf_branches__open_and_load();
+ if (CHECK(!skel, "test_perf_branches_load",
+ "perf_branches skeleton failed\n"))
+ goto out_destroy;
+
+ /* 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_destroy;
+
+ /* attach perf_event */
+ link = bpf_program__attach_perf_event(skel->progs.perf_branches, 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(skel->maps.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 (CHECK(err, "set_affinity", "cpu #0, err %d\n", err))
+ goto out_free_pb;
+ /* spin the loop for a while (random high number) */
+ 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_destroy:
+ test_perf_branches__destroy(skel);
+}
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..6811ad5839e7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_perf_branches.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <stddef.h>
+#include <linux/ptrace.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_trace_helpers.h"
+
+struct fake_perf_branch_entry {
+ __u64 _a;
+ __u64 _b;
+ __u64 _c;
+};
+
+struct output {
+ int required_size;
+ int written_stack;
+ int written_map;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(int));
+ __uint(value_size, sizeof(int));
+} perf_buf_map SEC(".maps");
+
+typedef struct fake_perf_branch_entry fpbe_t[30];
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, fpbe_t);
+} scratch_map SEC(".maps");
+
+SEC("perf_event")
+int perf_branches(void *ctx)
+{
+ struct fake_perf_branch_entry entries[4] = {0};
+ struct output output = {0};
+ __u32 key = 0, *value;
+
+ /* write to stack */
+ output.written_stack =
+ bpf_perf_prog_read_branches(ctx, entries,
+ sizeof(entries), 0);
+ /* ignore spurious events */
+ if (!output.written_stack)
+ return 1;
+
+ /* get required size */
+ output.required_size =
+ bpf_perf_prog_read_branches(ctx, NULL, 0, BPF_F_GET_BR_SIZE);
+
+ /* write to map */
+ value = bpf_map_lookup_elem(&scratch_map, &key);
+ if (value)
+ output.written_map =
+ bpf_perf_prog_read_branches(ctx,
+ value,
+ 30 * sizeof(struct fake_perf_branch_entry),
+ 0);
+
+ /* ignore spurious events */
+ if (!output.written_map)
+ return 1;
+
+ bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
+ &output, sizeof(output));
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.21.1
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