Merge branch 'bpf-dynamic-relinking'

Alexei Starovoitov says:

====================
The last few month BPF community has been discussing an approach to call
chaining, since exiting bpt_tail_call() mechanism used in production XDP
programs has plenty of downsides. The outcome of these discussion was a
conclusion to implement dynamic re-linking of BPF programs. Where rootlet XDP
program attached to a netdevice can programmatically define a policy of
execution of other XDP programs. Such rootlet would be compiled as normal XDP
program and provide a number of placeholder global functions which later can be
replaced with future XDP programs. BPF trampoline, function by function
verification were building blocks towards that goal. The patch 1 is a final
building block. It introduces dynamic program extensions. A number of
improvements like more flexible function by function verification and better
libbpf api will be implemented in future patches.

v1->v2:
- addressed Andrii's comments
- rebase
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

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();
 }