[PATCH bpf-next 3/3] bpf: Add perf_event_read_sample test cases

[Namhyung Kim]

It checks the bpf_perf_event_read_sample() helper with and without buffer
for supported PERF_SAMPLE_* flags.  The BPF program can control sample
data using the return value after checking the sample data and size.

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 .../selftests/bpf/prog_tests/perf_sample.c    | 172 ++++++++++++++++++
 .../selftests/bpf/progs/test_perf_sample.c    |  28 +++
 2 files changed, 200 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_sample.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_perf_sample.c

diff --git a/tools/testing/selftests/bpf/prog_tests/perf_sample.c b/tools/testing/selftests/bpf/prog_tests/perf_sample.c
new file mode 100644
index 000000000000..eee11f23196c
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/perf_sample.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <linux/perf_event.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+
+#include <test_progs.h>
+#include "test_perf_sample.skel.h"
+
+#ifndef noinline
+#define noinline __attribute__((noinline))
+#endif
+
+/* treat user-stack data as invalid (for testing only) */
+#define PERF_SAMPLE_INVALID  PERF_SAMPLE_STACK_USER
+
+#define PERF_MMAP_SIZE  8192
+#define DATA_MMAP_SIZE  4096
+
+static int perf_fd = -1;
+static void *perf_ringbuf;
+static struct test_perf_sample *skel;
+
+static int open_perf_event(u64 sample_flags)
+{
+	struct perf_event_attr attr = {
+		.type = PERF_TYPE_SOFTWARE,
+		.config = PERF_COUNT_SW_PAGE_FAULTS,
+		.sample_type = sample_flags,
+		.sample_period = 1,
+		.disabled = 1,
+		.size = sizeof(attr),
+	};
+	int fd;
+	void *ptr;
+
+	fd = syscall(SYS_perf_event_open, &attr, 0, -1, -1, 0);
+	if (!ASSERT_GT(fd, 0, "perf_event_open"))
+		return -1;
+
+	ptr = mmap(NULL, PERF_MMAP_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	if (!ASSERT_NEQ(ptr, MAP_FAILED, "mmap")) {
+		close(fd);
+		return -1;
+	}
+
+	perf_fd = fd;
+	perf_ringbuf = ptr;
+
+	return 0;
+}
+
+static void close_perf_event(void)
+{
+	if (perf_fd == -1)
+		return;
+
+	munmap(perf_ringbuf, PERF_MMAP_SIZE);
+	close(perf_fd);
+
+	perf_fd = -1;
+	perf_ringbuf = NULL;
+}
+
+static noinline void trigger_perf_event(void)
+{
+	int *buf = mmap(NULL, DATA_MMAP_SIZE, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
+
+	if (!ASSERT_NEQ(buf, MAP_FAILED, "mmap"))
+		return;
+
+	ioctl(perf_fd, PERF_EVENT_IOC_ENABLE);
+
+	/* it should generate a page fault which triggers the perf_event */
+	*buf = 1;
+
+	ioctl(perf_fd, PERF_EVENT_IOC_DISABLE);
+
+	munmap(buf, DATA_MMAP_SIZE);
+}
+
+/* check if the perf ringbuf has a sample data */
+static int check_perf_event(void)
+{
+	struct perf_event_mmap_page *page = perf_ringbuf;
+	struct perf_event_header *hdr;
+
+	if (page->data_head == page->data_tail)
+		return 0;
+
+	hdr = perf_ringbuf + page->data_offset;
+
+	if (hdr->type != PERF_RECORD_SAMPLE)
+		return 0;
+
+	return 1;
+}
+
+static void setup_perf_sample_bpf_skel(u64 sample_flags)
+{
+	struct bpf_link *link;
+
+	skel = test_perf_sample__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "test_perf_sample_open_and_load"))
+		return;
+
+	skel->bss->sample_flag = sample_flags;
+	skel->bss->sample_size = sizeof(sample_flags);
+
+	link = bpf_program__attach_perf_event(skel->progs.perf_sample_filter, perf_fd);
+	if (!ASSERT_OK_PTR(link, "bpf_program__attach_perf_event"))
+		return;
+}
+
+static void clean_perf_sample_bpf_skel(void)
+{
+	test_perf_sample__detach(skel);
+	test_perf_sample__destroy(skel);
+}
+
+static void test_perf_event_read_sample_invalid(void)
+{
+	u64 flags = PERF_SAMPLE_INVALID;
+
+	if (open_perf_event(flags) < 0)
+		return;
+	setup_perf_sample_bpf_skel(flags);
+	trigger_perf_event();
+	ASSERT_EQ(check_perf_event(), 0, "number of sample");
+	clean_perf_sample_bpf_skel();
+	close_perf_event();
+}
+
+static void test_perf_event_read_sample_ip(void)
+{
+	u64 flags = PERF_SAMPLE_IP;
+
+	if (open_perf_event(flags) < 0)
+		return;
+	setup_perf_sample_bpf_skel(flags);
+	trigger_perf_event();
+	ASSERT_EQ(check_perf_event(), 1, "number of sample");
+	clean_perf_sample_bpf_skel();
+	close_perf_event();
+}
+
+static void test_perf_event_read_sample_addr(void)
+{
+	u64 flags = PERF_SAMPLE_ADDR;
+
+	if (open_perf_event(flags) < 0)
+		return;
+	setup_perf_sample_bpf_skel(flags);
+	trigger_perf_event();
+	ASSERT_EQ(check_perf_event(), 1, "number of sample");
+	clean_perf_sample_bpf_skel();
+	close_perf_event();
+}
+
+void test_perf_event_read_sample(void)
+{
+	if (test__start_subtest("perf_event_read_sample_invalid"))
+		test_perf_event_read_sample_invalid();
+	if (test__start_subtest("perf_event_read_sample_ip"))
+		test_perf_event_read_sample_ip();
+	if (test__start_subtest("perf_event_read_sample_addr"))
+		test_perf_event_read_sample_addr();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_perf_sample.c b/tools/testing/selftests/bpf/progs/test_perf_sample.c
new file mode 100644
index 000000000000..79664acafcd9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_perf_sample.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2022 Google
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+unsigned long long sample_flag;
+unsigned long long sample_size;
+
+SEC("perf_event")
+int perf_sample_filter(void *ctx)
+{
+	long size;
+	unsigned long long buf[1] = {};
+
+	size = bpf_perf_event_read_sample(ctx, NULL, 0, sample_flag);
+	if (size != sample_size)
+		return 0;
+
+	if (bpf_perf_event_read_sample(ctx, buf, sizeof(buf), sample_flag) < 0)
+		return 0;
+
+	/* generate sample data */
+	return 1;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.38.1.273.g43a17bfeac-goog