[PATCH bpf 2/2] selftests/bpf: Add selftest for calling global functions from freplace

[Toke Høiland-Jørgensen <toke@xxxxxxxxxx>]

Add a selftest that calls a global function with a context object parameter
from an freplace function to check that the program context type is
correctly converted to the freplace target when fetching the context type
from the kernel BTF.

Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
---
 .../selftests/bpf/prog_tests/fexit_bpf2bpf.c  | 13 ++++++++++
 .../bpf/progs/freplace_global_func.c          | 24 +++++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/freplace_global_func.c

diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
index d9aad15e0d24..6e86a1d92e97 100644
--- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
+++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
@@ -395,6 +395,17 @@ static void test_func_map_prog_compatibility(void)
 				     "./test_attach_probe.o");
 }
 
+static void test_func_replace_global_func(void)
+{
+	const char *prog_name[] = {
+		"freplace/test_pkt_access",
+	};
+	test_fexit_bpf2bpf_common("./freplace_global_func.o",
+				  "./test_pkt_access.o",
+				  ARRAY_SIZE(prog_name),
+				  prog_name, false, NULL);
+}
+
 /* NOTE: affect other tests, must run in serial mode */
 void serial_test_fexit_bpf2bpf(void)
 {
@@ -416,4 +427,6 @@ void serial_test_fexit_bpf2bpf(void)
 		test_func_replace_multi();
 	if (test__start_subtest("fmod_ret_freplace"))
 		test_fmod_ret_freplace();
+	if (test__start_subtest("func_replace_global_func"))
+		test_func_replace_global_func();
 }
diff --git a/tools/testing/selftests/bpf/progs/freplace_global_func.c b/tools/testing/selftests/bpf/progs/freplace_global_func.c
new file mode 100644
index 000000000000..d9f8276229cc
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/freplace_global_func.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Facebook */
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_tracing.h>
+
+__attribute__ ((noinline))
+int test_ctx_global_func(struct __sk_buff *skb)
+{
+	volatile int retval = 1;
+	return retval;
+}
+
+__u64 test_pkt_access_global_func = 0;
+SEC("freplace/test_pkt_access")
+int new_test_pkt_access(struct __sk_buff *skb)
+{
+	test_pkt_access_global_func = test_ctx_global_func(skb);
+	return -1;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.36.1