linux-kernel - [PATCH bpf-next 5/5] selftests/bpf: add callchain

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Message-ID: <20200711012639.3429622-6-songliubraving@fb.com>
Date:   Fri, 10 Jul 2020 18:26:39 -0700
From:   Song Liu <songliubraving@...com>
To:     <linux-kernel@...r.kernel.org>, <bpf@...r.kernel.org>,
        <netdev@...r.kernel.org>
CC:     <ast@...nel.org>, <daniel@...earbox.net>, <kernel-team@...com>,
        <john.fastabend@...il.com>, <kpsingh@...omium.org>,
        <brouer@...hat.com>, <peterz@...radead.org>,
        Song Liu <songliubraving@...com>
Subject: [PATCH bpf-next 5/5] selftests/bpf: add callchain_stackid

This tests new helper function bpf_get_callchain_stackid(), which is the
alternative to bpf_get_stackid() for perf_event with PEBS entry.

Signed-off-by: Song Liu <songliubraving@...com>
---
 .../bpf/prog_tests/callchain_stackid.c        | 61 +++++++++++++++++++
 .../selftests/bpf/progs/callchain_stackid.c   | 37 +++++++++++
 2 files changed, 98 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/callchain_stackid.c
 create mode 100644 tools/testing/selftests/bpf/progs/callchain_stackid.c

diff --git a/tools/testing/selftests/bpf/prog_tests/callchain_stackid.c b/tools/testing/selftests/bpf/prog_tests/callchain_stackid.c
new file mode 100644
index 0000000000000..ebe6251324a1a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/callchain_stackid.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+#include <test_progs.h>
+#include "callchain_stackid.skel.h"
+
+void test_callchain_stackid(void)
+{
+	struct perf_event_attr attr = {
+		/* .type = PERF_TYPE_SOFTWARE, */
+		.type = PERF_TYPE_HARDWARE,
+		.config = PERF_COUNT_HW_CPU_CYCLES,
+		.precise_ip = 2,
+		.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_BRANCH_STACK |
+			PERF_SAMPLE_CALLCHAIN,
+		.branch_sample_type = PERF_SAMPLE_BRANCH_USER |
+			PERF_SAMPLE_BRANCH_NO_FLAGS |
+			PERF_SAMPLE_BRANCH_NO_CYCLES |
+			PERF_SAMPLE_BRANCH_CALL_STACK,
+		.sample_period = 5000,
+		.size = sizeof(struct perf_event_attr),
+	};
+	struct callchain_stackid *skel;
+	__u32 duration = 0;
+	int pmu_fd, err;
+
+	skel = callchain_stackid__open();
+
+	if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
+		return;
+
+	/* override program type */
+	bpf_program__set_perf_event(skel->progs.oncpu);
+
+	err = callchain_stackid__load(skel);
+	if (CHECK(err, "skel_load", "skeleton load failed: %d\n", err))
+		goto cleanup;
+
+	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
+			 0 /* cpu 0 */, -1 /* group id */,
+			 0 /* flags */);
+	if (pmu_fd < 0) {
+		printf("%s:SKIP:cpu doesn't support the event\n", __func__);
+		test__skip();
+		goto cleanup;
+	}
+
+	skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
+							   pmu_fd);
+	if (CHECK(IS_ERR(skel->links.oncpu), "attach_perf_event",
+		  "err %ld\n", PTR_ERR(skel->links.oncpu))) {
+		close(pmu_fd);
+		goto cleanup;
+	}
+	usleep(500000);
+
+	CHECK(skel->data->total_val == 1, "get_callchain_stack", "failed\n");
+	close(pmu_fd);
+
+cleanup:
+	callchain_stackid__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/callchain_stackid.c b/tools/testing/selftests/bpf/progs/callchain_stackid.c
new file mode 100644
index 0000000000000..aab2c736a0a45
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/callchain_stackid.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+#ifndef PERF_MAX_STACK_DEPTH
+#define PERF_MAX_STACK_DEPTH         127
+#endif
+
+#ifndef BPF_F_USER_STACK
+#define BPF_F_USER_STACK		(1ULL << 8)
+#endif
+
+typedef __u64 stack_trace_t[PERF_MAX_STACK_DEPTH];
+struct {
+	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
+	__uint(max_entries, 16384);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(stack_trace_t));
+} stackmap SEC(".maps");
+
+long total_val = 1;
+
+SEC("perf_event")
+int oncpu(struct bpf_perf_event_data *ctx)
+{
+	long val;
+
+	val = bpf_get_callchain_stackid(ctx->callchain, &stackmap, 0);
+
+	if (val > 0)
+		total_val += val;
+
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
-- 
2.24.1