linux-kernel - [PATCH v4 bpf-next 4/4] selftests/bpf: add get_stackid_cannot

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Message-ID: <20200722184210.4078256-5-songliubraving@fb.com>
Date:   Wed, 22 Jul 2020 11:42:10 -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 v4 bpf-next 4/4] selftests/bpf: add get_stackid_cannot_attach

This test confirms that BPF program that calls bpf_get_stackid() cannot
attach to perf_event with precise_ip > 0 but not PERF_SAMPLE_CALLCHAIN;
and cannot attach if the perf_event has exclude_callchain_kernel.

Signed-off-by: Song Liu <songliubraving@...com>
---
 .../prog_tests/get_stackid_cannot_attach.c    | 91 +++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/get_stackid_cannot_attach.c

diff --git a/tools/testing/selftests/bpf/prog_tests/get_stackid_cannot_attach.c b/tools/testing/selftests/bpf/prog_tests/get_stackid_cannot_attach.c
new file mode 100644
index 0000000000000..f13149d279bc9
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/get_stackid_cannot_attach.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+#include <test_progs.h>
+#include "test_stacktrace_build_id.skel.h"
+
+void test_get_stackid_cannot_attach(void)
+{
+	struct perf_event_attr attr = {
+		/* .type = PERF_TYPE_SOFTWARE, */
+		.type = PERF_TYPE_HARDWARE,
+		.config = PERF_COUNT_HW_CPU_CYCLES,
+		.precise_ip = 1,
+		.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_BRANCH_STACK,
+		.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 test_stacktrace_build_id *skel;
+	__u32 duration = 0;
+	int pmu_fd, err;
+
+	skel = test_stacktrace_build_id__open();
+	if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
+		return;
+
+	/* override program type */
+	bpf_program__set_perf_event(skel->progs.oncpu);
+
+	err = test_stacktrace_build_id__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 && errno == ENOENT) {
+		printf("%s:SKIP:cannot open PERF_COUNT_HW_CPU_CYCLES with precise_ip > 0\n",
+		       __func__);
+		test__skip();
+		goto cleanup;
+	}
+	if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
+		  pmu_fd, errno))
+		goto cleanup;
+
+	skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
+							   pmu_fd);
+	CHECK(!IS_ERR(skel->links.oncpu), "attach_perf_event_no_callchain",
+	      "should have failed\n");
+	close(pmu_fd);
+
+	/* add PERF_SAMPLE_CALLCHAIN, attach should succeed */
+	attr.sample_type |= PERF_SAMPLE_CALLCHAIN;
+
+	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
+			 0 /* cpu 0 */, -1 /* group id */,
+			 0 /* flags */);
+
+	if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
+		  pmu_fd, errno))
+		goto cleanup;
+
+	skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
+							   pmu_fd);
+	CHECK(IS_ERR(skel->links.oncpu), "attach_perf_event_callchain",
+	      "err: %ld\n", PTR_ERR(skel->links.oncpu));
+	close(pmu_fd);
+
+	/* add exclude_callchain_kernel, attach should fail */
+	attr.exclude_callchain_kernel = 1;
+
+	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
+			 0 /* cpu 0 */, -1 /* group id */,
+			 0 /* flags */);
+
+	if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
+		  pmu_fd, errno))
+		goto cleanup;
+
+	skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
+							   pmu_fd);
+	CHECK(!IS_ERR(skel->links.oncpu), "attach_perf_event_exclude_callchain_kernel",
+	      "should have failed\n");
+	close(pmu_fd);
+
+cleanup:
+	test_stacktrace_build_id__destroy(skel);
+}
-- 
2.24.1