selftests/bpf: Add tests for program extensions

Add program extension tests that build on top of fexit_bpf2bpf tests.
Replace three global functions in previously loaded test_pkt_access.c program
with three new implementations:
int get_skb_len(struct __sk_buff *skb);
int get_constant(long val);
int get_skb_ifindex(int val, struct __sk_buff *skb, int var);
New function return the same results as original only if arguments match.

new_get_skb_ifindex() demonstrates that 'skb' argument doesn't have to be first
and only argument of BPF program. All normal skb based accesses are available.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20200121005348.2769920-4-ast@kernel.org

1 files changed, 19 insertions, 1 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
index 7d3740d38965..db5c74d2ce6d 100644
--- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
+++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
@@ -26,7 +26,7 @@ static void test_fexit_bpf2bpf_common(const char *obj_file,
 
 	link = calloc(sizeof(struct bpf_link *), prog_cnt);
 	prog = calloc(sizeof(struct bpf_program *), prog_cnt);
-	result = malloc(prog_cnt * sizeof(u64));
+	result = malloc((prog_cnt + 32 /* spare */) * sizeof(u64));
 	if (CHECK(!link || !prog || !result, "alloc_memory",
 		  "failed to alloc memory"))
 		goto close_prog;
@@ -106,8 +106,26 @@ static void test_target_yes_callees(void)
 				  prog_name);
 }
 
+static void test_func_replace(void)
+{
+	const char *prog_name[] = {
+		"fexit/test_pkt_access",
+		"fexit/test_pkt_access_subprog1",
+		"fexit/test_pkt_access_subprog2",
+		"fexit/test_pkt_access_subprog3",
+		"freplace/get_skb_len",
+		"freplace/get_skb_ifindex",
+		"freplace/get_constant",
+	};
+	test_fexit_bpf2bpf_common("./fexit_bpf2bpf.o",
+				  "./test_pkt_access.o",
+				  ARRAY_SIZE(prog_name),
+				  prog_name);
+}
+
 void test_fexit_bpf2bpf(void)
 {
 	test_target_no_callees();
 	test_target_yes_callees();
+	test_func_replace();
 }