selftests/bpf: Add test for bpf_get_func_ip helper

Adding test for bpf_get_func_ip helper for fentry, fexit,
kprobe, kretprobe and fmod_ret programs.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-6-jolsa@kernel.org

tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c

+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include "get_func_ip_test.skel.h"
+
+void test_get_func_ip_test(void)
+{
+	struct get_func_ip_test *skel = NULL;
+	__u32 duration = 0, retval;
+	int err, prog_fd;
+
+	skel = get_func_ip_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "get_func_ip_test__open_and_load"))
+		return;
+
+	err = get_func_ip_test__attach(skel);
+	if (!ASSERT_OK(err, "get_func_ip_test__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");
+
+	prog_fd = bpf_program__fd(skel->progs.test5);
+	err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
+				NULL, NULL, &retval, &duration);
+
+	ASSERT_OK(err, "test_run");
+
+	ASSERT_EQ(skel->bss->test1_result, 1, "test1_result");
+	ASSERT_EQ(skel->bss->test2_result, 1, "test2_result");
+	ASSERT_EQ(skel->bss->test3_result, 1, "test3_result");
+	ASSERT_EQ(skel->bss->test4_result, 1, "test4_result");
+	ASSERT_EQ(skel->bss->test5_result, 1, "test5_result");
+
+cleanup:
+	get_func_ip_test__destroy(skel);
+}

tools/testing/selftests/bpf/progs/get_func_ip_test.c

+// 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_modify_return_test __ksym;
+
+__u64 test1_result = 0;
+SEC("fentry/bpf_fentry_test1")
+int BPF_PROG(test1, int a)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	test1_result = (const void *) addr == &bpf_fentry_test1;
+	return 0;
+}
+
+__u64 test2_result = 0;
+SEC("fexit/bpf_fentry_test2")
+int BPF_PROG(test2, int a)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	test2_result = (const void *) addr == &bpf_fentry_test2;
+	return 0;
+}
+
+__u64 test3_result = 0;
+SEC("kprobe/bpf_fentry_test3")
+int test3(struct pt_regs *ctx)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	test3_result = (const void *) addr == &bpf_fentry_test3;
+	return 0;
+}
+
+__u64 test4_result = 0;
+SEC("kretprobe/bpf_fentry_test4")
+int BPF_KRETPROBE(test4)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	test4_result = (const void *) addr == &bpf_fentry_test4;
+	return 0;
+}
+
+__u64 test5_result = 0;
+SEC("fmod_ret/bpf_modify_return_test")
+int BPF_PROG(test5, int a, int *b, int ret)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	test5_result = (const void *) addr == &bpf_modify_return_test;
+	return ret;
+}