[PATCH v2 7/7] perf test: Add 'perf test BPF'

[Wang Nan]

This patch adds BPF testcase for testing BPF event filtering.

By utilizing the result of 'perf test LLVM', this patch compiles the
eBPF sample program then test it ability. The BPF script in 'perf test
LLVM' let only 50% samples generated by epoll_pwait() be captured.
This patch runs that system call for 111 times, so the resule should
contain 56 samples.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
 tools/perf/tests/Build          |   1 +
 tools/perf/tests/bpf.c          | 209 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/tests/builtin-test.c |   4 +
 tools/perf/tests/tests.h        |   1 +
 tools/perf/util/bpf-loader.c    |  24 ++++-
 tools/perf/util/bpf-loader.h    |  10 ++
 6 files changed, 248 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/tests/bpf.c

diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index a47b211..f41ebf8 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -32,6 +32,7 @@ perf-y += parse-no-sample-id-all.o
 perf-y += kmod-path.o
 perf-y += thread-map.o
 perf-y += llvm.o llvm-src-base.o llvm-src-kbuild.o
+perf-y += bpf.o
 perf-y += topology.o
 
 $(OUTPUT)tests/llvm-src-base.c: tests/bpf-script-example.c
diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
new file mode 100644
index 0000000..ec16f78
--- /dev/null
+++ b/tools/perf/tests/bpf.c
@@ -0,0 +1,209 @@
+#include <stdio.h>
+#include <sys/epoll.h>
+#include <util/bpf-loader.h>
+#include <util/evlist.h>
+#include "tests.h"
+#include "llvm.h"
+#include "debug.h"
+#define NR_ITERS       111
+
+#ifdef HAVE_LIBBPF_SUPPORT
+
+static int epoll_pwait_loop(void)
+{
+	int i;
+
+	/* Should fail NR_ITERS times */
+	for (i = 0; i < NR_ITERS; i++)
+		epoll_pwait(-(i + 1), NULL, 0, 0, NULL);
+	return 0;
+}
+
+static struct {
+	enum test_llvm__testcase prog_id;
+	const char *desc;
+	const char *name;
+	const char *msg_compile_fail;
+	const char *msg_load_fail;
+	int (*target_func)(void);
+	int expect_result;
+} bpf_testcase_table[] = {
+	{
+		LLVM_TESTCASE_BASE,
+		"Test basic BPF filtering",
+		"[basic_bpf_test]",
+		"fix 'perf test LLVM' first",
+		"load bpf object failed",
+		&epoll_pwait_loop,
+		(NR_ITERS + 1) / 2,
+	},
+};
+
+static int do_test(struct bpf_object *obj, int (*func)(void),
+		   int expect)
+{
+	struct record_opts opts = {
+		.target = {
+			.uid = UINT_MAX,
+			.uses_mmap = true,
+		},
+		.freq	      = 0,
+		.mmap_pages   = 256,
+		.default_interval = 1,
+	};
+
+	char pid[16];
+	char sbuf[STRERR_BUFSIZE];
+	struct perf_evlist *evlist;
+	int i, ret = TEST_FAIL, err = 0, count = 0;
+
+	struct parse_events_evlist parse_evlist;
+	struct parse_events_error parse_error;
+
+	bzero(&parse_error, sizeof(parse_error));
+	bzero(&parse_evlist, sizeof(parse_evlist));
+	parse_evlist.error = &parse_error;
+	INIT_LIST_HEAD(&parse_evlist.list);
+
+	err = parse_events_load_bpf_obj(&parse_evlist, &parse_evlist.list, obj);
+	if (err || list_empty(&parse_evlist.list)) {
+		pr_debug("Failed to add events selected by BPF\n");
+		if (!err)
+			return TEST_FAIL;
+	}
+
+	snprintf(pid, sizeof(pid), "%d", getpid());
+	pid[sizeof(pid) - 1] = '\0';
+	opts.target.tid = opts.target.pid = pid;
+
+	/* Instead of perf_evlist__new_default, don't add default events */
+	evlist = perf_evlist__new();
+	if (!evlist) {
+		pr_debug("No ehough memory to create evlist\n");
+		return TEST_FAIL;
+	}
+
+	err = perf_evlist__create_maps(evlist, &opts.target);
+	if (err < 0) {
+		pr_debug("Not enough memory to create thread/cpu maps\n");
+		goto out_delete_evlist;
+	}
+
+	perf_evlist__splice_list_tail(evlist, &parse_evlist.list);
+	evlist->nr_groups = parse_evlist.nr_groups;
+
+	perf_evlist__config(evlist, &opts);
+
+	err = perf_evlist__open(evlist);
+	if (err < 0) {
+		pr_debug("perf_evlist__open: %s\n",
+			 strerror_r(errno, sbuf, sizeof(sbuf)));
+		goto out_delete_evlist;
+	}
+
+	err = perf_evlist__mmap(evlist, opts.mmap_pages, false);
+	if (err < 0) {
+		pr_debug("perf_evlist__mmap: %s\n",
+			 strerror_r(errno, sbuf, sizeof(sbuf)));
+		goto out_delete_evlist;
+	}
+
+	perf_evlist__enable(evlist);
+	(*func)();
+	perf_evlist__disable(evlist);
+
+	for (i = 0; i < evlist->nr_mmaps; i++) {
+		union perf_event *event;
+
+		while ((event = perf_evlist__mmap_read(evlist, i)) != NULL) {
+			const u32 type = event->header.type;
+
+			if (type == PERF_RECORD_SAMPLE)
+				count ++;
+		}
+	}
+
+	if (count != expect)
+		pr_debug("BPF filter result incorrect\n");
+
+	ret = TEST_OK;
+
+out_delete_evlist:
+	perf_evlist__delete(evlist);
+	return ret;
+}
+
+static struct bpf_object *
+prepare_bpf(void *obj_buf, size_t obj_buf_sz, const char *name)
+{
+	struct bpf_object *obj;
+
+	obj = bpf__prepare_load_buffer(obj_buf, obj_buf_sz, name);
+	if (IS_ERR(obj)) {
+		pr_debug("Compile BPF program failed.\n");
+		return NULL;
+	}
+	return obj;
+}
+
+static int __test__bpf(int index)
+{
+	int ret;
+	void *obj_buf;
+	size_t obj_buf_sz;
+	struct bpf_object *obj;
+
+	ret = test_llvm__fetch_bpf_obj(&obj_buf, &obj_buf_sz,
+				       bpf_testcase_table[index].prog_id,
+				       true);
+	if (ret != TEST_OK || !obj_buf || !obj_buf_sz) {
+		pr_debug("Unable to get BPF object, %s\n",
+			 bpf_testcase_table[index].msg_compile_fail);
+		if (index == 0)
+			return TEST_SKIP;
+		else
+			return TEST_FAIL;
+	}
+
+	obj = prepare_bpf(obj_buf, obj_buf_sz,
+			  bpf_testcase_table[index].name);
+	if (!obj) {
+		ret = TEST_FAIL;
+		goto out;
+	}
+
+	ret = do_test(obj,
+		      bpf_testcase_table[index].target_func,
+		      bpf_testcase_table[index].expect_result);
+out:
+	bpf__clear();
+	return ret;
+}
+
+int test__bpf(void)
+{
+	unsigned int i;
+	int err;
+
+	if (geteuid() != 0) {
+		pr_debug("Only root can run BPF test\n");
+		return TEST_SKIP;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(bpf_testcase_table); i++) {
+		err = __test__bpf(i);
+
+		if (err != TEST_OK)
+			return err;
+	}
+
+	return TEST_OK;
+}
+
+#else
+int test__bpf(void)
+{
+	pr_debug("Skip BPF test because BPF support is not compiled\n");
+	return TEST_SKIP;
+}
+#endif
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 66f72d3..7b0120a 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -166,6 +166,10 @@ static struct test generic_tests[] = {
 		.func = test_session_topology,
 	},
 	{
+		.desc = "Test BPF filter",
+		.func = test__bpf,
+	},
+	{
 		.func = NULL,
 	},
 };
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index c804869..3c8734a 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -66,6 +66,7 @@ int test__fdarray__add(void);
 int test__kmod_path__parse(void);
 int test__thread_map(void);
 int test__llvm(void);
+int test__bpf(void);
 int test_session_topology(void);
 
 #if defined(__arm__) || defined(__aarch64__)
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 19b496b..636a4d7 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -34,10 +34,32 @@ struct bpf_prog_priv {
 	struct perf_probe_event pev;
 };
 
+static bool libbpf_initialized;
+
+struct bpf_object *
+bpf__prepare_load_buffer(void *obj_buf, size_t obj_buf_sz, const char *name)
+{
+	struct bpf_object *obj;
+
+	if (!libbpf_initialized) {
+		libbpf_set_print(libbpf_warning,
+				 libbpf_info,
+				 libbpf_debug);
+		libbpf_initialized = true;
+	}
+
+	obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, name);
+	if (IS_ERR(obj)) {
+		pr_debug("bpf: failed to load buffer\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	return obj;
+}
+
 struct bpf_object *bpf__prepare_load(const char *filename, bool source)
 {
 	struct bpf_object *obj;
-	static bool libbpf_initialized;
 
 	if (!libbpf_initialized) {
 		libbpf_set_print(libbpf_warning,
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index 2c39710..bc82133 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -34,6 +34,9 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source);
 int bpf__strerror_prepare_load(const char *filename, bool source,
 			       int err, char *buf, size_t size);
 
+struct bpf_object *bpf__prepare_load_buffer(void *obj_buf, size_t obj_buf_sz,
+					    const char *name);
+
 void bpf__clear(void);
 
 int bpf__probe(struct bpf_object *obj);
@@ -55,6 +58,13 @@ bpf__prepare_load(const char *filename __maybe_unused,
 	return ERR_PTR(-ENOTSUP);
 }
 
+static inline struct bpf_object *
+bpf__prepare_load_buffer(void *obj_buf __maybe_unused,
+					   size_t obj_buf_sz __maybe_unused)
+{
+	return ERR_PTR(-ENOTSUP);
+}
+
 static inline void bpf__clear(void) { }
 
 static inline int bpf__probe(struct bpf_object *obj __maybe_unused) { return 0;}
-- 
1.8.3.4

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