Subject: [PATCH 7/8] selftest/bpf: Add fprobe attach test

From: Jiri Olsa <[email-masked]>
Date: Wed, 2 Feb 2022 14:53:32 +0100

Adding kprobe attach test that uses new fprobe interface
to attach kprobe program to multiple functions.

The test is attaching to bpf_fentry_test* functions and
uses single trampoline program bpf_prog_test_run to trigger
bpf_fentry_test* functions.

Signed-off-by: Jiri Olsa <[email-masked]>
---
 .../selftests/bpf/prog_tests/fprobe_test.c    | 117 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/fprobe.c    |  58 +++++++++
 2 files changed, 175 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/fprobe_test.c
 create mode 100644 tools/testing/selftests/bpf/progs/fprobe.c

diff --git a/tools/testing/selftests/bpf/prog_tests/fprobe_test.c b/tools/testing/selftests/bpf/prog_tests/fprobe_test.c
new file mode 100644
index 000000000000..dcbde37ec369
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/fprobe_test.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include "fprobe.skel.h"
+#include "trace_helpers.h"
+
+static void test_skel_api(void)
+{
+	struct fprobe *skel = NULL;
+	__u32 duration = 0, retval;
+	int err, prog_fd;
+
+	skel = fprobe__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "fprobe__open_and_load"))
+		goto cleanup;
+
+	err = fprobe__attach(skel);
+	if (!ASSERT_OK(err, "fprobe__attach"))
+		goto cleanup;
+
+	prog_fd = bpf_program__fd(skel->progs.test1);
+	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
+				NULL, NULL, &retval, &duration);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(retval, 0, "test_run");
+
+	ASSERT_EQ(skel->bss->test2_result, 8, "test2_result");
+	ASSERT_EQ(skel->bss->test3_result, 8, "test3_result");
+
+cleanup:
+	fprobe__destroy(skel);
+}
+
+static void test_link_api(struct bpf_link_create_opts *opts)
+{
+	int err, prog_fd, link1_fd = -1, link2_fd = -1;
+	struct fprobe *skel = NULL;
+	__u32 duration = 0, retval;
+
+	skel = fprobe__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "fentry_raw_skel_load"))
+		goto cleanup;
+
+	prog_fd = bpf_program__fd(skel->progs.test2);
+	link1_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_FPROBE, opts);
+	if (!ASSERT_GE(link1_fd, 0, "link_fd"))
+		goto cleanup;
+
+	opts->fprobe.flags = BPF_F_FPROBE_RETURN;
+	prog_fd = bpf_program__fd(skel->progs.test3);
+	link2_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_FPROBE, opts);
+	if (!ASSERT_GE(link2_fd, 0, "link_fd"))
+		goto cleanup;
+
+	skel->bss->test2_result = 0;
+	skel->bss->test3_result = 0;
+
+	prog_fd = bpf_program__fd(skel->progs.test1);
+	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
+				NULL, NULL, &retval, &duration);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(retval, 0, "test_run");
+
+	ASSERT_EQ(skel->bss->test2_result, 8, "test2_result");
+	ASSERT_EQ(skel->bss->test3_result, 8, "test3_result");
+
+cleanup:
+	if (link1_fd != -1)
+		close(link1_fd);
+	if (link2_fd != -1)
+		close(link2_fd);
+	fprobe__destroy(skel);
+}
+
+static void test_link_api_addrs(void)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts);
+	__u64 addrs[8];
+
+	kallsyms_find("bpf_fentry_test1", &addrs[0]);
+	kallsyms_find("bpf_fentry_test2", &addrs[1]);
+	kallsyms_find("bpf_fentry_test3", &addrs[2]);
+	kallsyms_find("bpf_fentry_test4", &addrs[3]);
+	kallsyms_find("bpf_fentry_test5", &addrs[4]);
+	kallsyms_find("bpf_fentry_test6", &addrs[5]);
+	kallsyms_find("bpf_fentry_test7", &addrs[6]);
+	kallsyms_find("bpf_fentry_test8", &addrs[7]);
+
+	opts.fprobe.addrs = (__u64) addrs;
+	opts.fprobe.cnt = 8;
+	test_link_api(&opts);
+}
+
+static void test_link_api_syms(void)
+{
+	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts);
+	const char *syms[8] = {
+		"bpf_fentry_test1",
+		"bpf_fentry_test2",
+		"bpf_fentry_test3",
+		"bpf_fentry_test4",
+		"bpf_fentry_test5",
+		"bpf_fentry_test6",
+		"bpf_fentry_test7",
+		"bpf_fentry_test8",
+	};
+
+	opts.fprobe.syms = (__u64) syms;
+	opts.fprobe.cnt = 8;
+	test_link_api(&opts);
+}
+
+void test_fprobe_test(void)
+{
+	test_skel_api();
+	test_link_api_syms();
+	test_link_api_addrs();
+}
diff --git a/tools/testing/selftests/bpf/progs/fprobe.c b/tools/testing/selftests/bpf/progs/fprobe.c
new file mode 100644
index 000000000000..baf7086203f9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/fprobe.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+extern const void bpf_fentry_test1 __ksym;
+extern const void bpf_fentry_test2 __ksym;
+extern const void bpf_fentry_test3 __ksym;
+extern const void bpf_fentry_test4 __ksym;
+extern const void bpf_fentry_test5 __ksym;
+extern const void bpf_fentry_test6 __ksym;
+extern const void bpf_fentry_test7 __ksym;
+extern const void bpf_fentry_test8 __ksym;
+
+/* No tests, just to trigger bpf_fentry_test* through tracing test_run */
+SEC("fentry/bpf_modify_return_test")
+int BPF_PROG(test1)
+{
+	return 0;
+}
+
+__u64 test2_result = 0;
+
+SEC("kprobe/bpf_fentry_test*")
+int test2(struct pt_regs *ctx)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	test2_result += (const void *) addr == &bpf_fentry_test1 ||
+			(const void *) addr == &bpf_fentry_test2 ||
+			(const void *) addr == &bpf_fentry_test3 ||
+			(const void *) addr == &bpf_fentry_test4 ||
+			(const void *) addr == &bpf_fentry_test5 ||
+			(const void *) addr == &bpf_fentry_test6 ||
+			(const void *) addr == &bpf_fentry_test7 ||
+			(const void *) addr == &bpf_fentry_test8;
+	return 0;
+}
+
+__u64 test3_result = 0;
+
+SEC("kretprobe/bpf_fentry_test*")
+int test3(struct pt_regs *ctx)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	test3_result += (const void *) addr == &bpf_fentry_test1 ||
+			(const void *) addr == &bpf_fentry_test2 ||
+			(const void *) addr == &bpf_fentry_test3 ||
+			(const void *) addr == &bpf_fentry_test4 ||
+			(const void *) addr == &bpf_fentry_test5 ||
+			(const void *) addr == &bpf_fentry_test6 ||
+			(const void *) addr == &bpf_fentry_test7 ||
+			(const void *) addr == &bpf_fentry_test8;
+	return 0;
+}
-- 
2.34.1