selftests/bpf: Add testcase for updating attached freplace prog to prog_array map

Add a selftest to confirm the issue, which gets -EINVAL when update
attached freplace prog to prog_array map, has been fixed.

cd tools/testing/selftests/bpf; ./test_progs -t tailcalls
328/25  tailcalls/tailcall_freplace:OK
328     tailcalls:OK
Summary: 1/25 PASSED, 0 SKIPPED, 0 FAILED

Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20240728114612.48486-3-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
index e01fabb8cc415978e3d2a6e1930c83c07195fcc4..21c5a37846adea7d10c39fdc76f61ebd37be0e2a 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c
+++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
@@ -5,7 +5,8 @@
 #include "tailcall_poke.skel.h"
 #include "tailcall_bpf2bpf_hierarchy2.skel.h"
 #include "tailcall_bpf2bpf_hierarchy3.skel.h"
-
+#include "tailcall_freplace.skel.h"
+#include "tc_bpf2bpf.skel.h"
 
 /* test_tailcall_1 checks basic functionality by patching multiple locations
  * in a single program for a single tail call slot with nop->jmp, jmp->nop
@@ -1495,6 +1496,66 @@ static void test_tailcall_bpf2bpf_hierarchy_3(void)
        RUN_TESTS(tailcall_bpf2bpf_hierarchy3);
 }
 
+/* test_tailcall_freplace checks that the attached freplace prog is OK to
+ * update the prog_array map.
+ */
+static void test_tailcall_freplace(void)
+{
+       struct tailcall_freplace *freplace_skel = NULL;
+       struct bpf_link *freplace_link = NULL;
+       struct bpf_program *freplace_prog;
+       struct tc_bpf2bpf *tc_skel = NULL;
+       int prog_fd, map_fd;
+       char buff[128] = {};
+       int err, key;
+
+       LIBBPF_OPTS(bpf_test_run_opts, topts,
+                   .data_in = buff,
+                   .data_size_in = sizeof(buff),
+                   .repeat = 1,
+       );
+
+       freplace_skel = tailcall_freplace__open();
+       if (!ASSERT_OK_PTR(freplace_skel, "tailcall_freplace__open"))
+               return;
+
+       tc_skel = tc_bpf2bpf__open_and_load();
+       if (!ASSERT_OK_PTR(tc_skel, "tc_bpf2bpf__open_and_load"))
+               goto out;
+
+       prog_fd = bpf_program__fd(tc_skel->progs.entry_tc);
+       freplace_prog = freplace_skel->progs.entry_freplace;
+       err = bpf_program__set_attach_target(freplace_prog, prog_fd, "subprog");
+       if (!ASSERT_OK(err, "set_attach_target"))
+               goto out;
+
+       err = tailcall_freplace__load(freplace_skel);
+       if (!ASSERT_OK(err, "tailcall_freplace__load"))
+               goto out;
+
+       freplace_link = bpf_program__attach_freplace(freplace_prog, prog_fd,
+                                                    "subprog");
+       if (!ASSERT_OK_PTR(freplace_link, "attach_freplace"))
+               goto out;
+
+       map_fd = bpf_map__fd(freplace_skel->maps.jmp_table);
+       prog_fd = bpf_program__fd(freplace_prog);
+       key = 0;
+       err = bpf_map_update_elem(map_fd, &key, &prog_fd, BPF_ANY);
+       if (!ASSERT_OK(err, "update jmp_table"))
+               goto out;
+
+       prog_fd = bpf_program__fd(tc_skel->progs.entry_tc);
+       err = bpf_prog_test_run_opts(prog_fd, &topts);
+       ASSERT_OK(err, "test_run");
+       ASSERT_EQ(topts.retval, 34, "test_run retval");
+
+out:
+       bpf_link__destroy(freplace_link);
+       tc_bpf2bpf__destroy(tc_skel);
+       tailcall_freplace__destroy(freplace_skel);
+}
+
 void test_tailcalls(void)
 {
        if (test__start_subtest("tailcall_1"))
@@ -1543,4 +1604,6 @@ void test_tailcalls(void)
                test_tailcall_bpf2bpf_hierarchy_fentry_entry();
        test_tailcall_bpf2bpf_hierarchy_2();
        test_tailcall_bpf2bpf_hierarchy_3();
+       if (test__start_subtest("tailcall_freplace"))
+               test_tailcall_freplace();
 }

diff --git a/tools/testing/selftests/bpf/progs/tailcall_freplace.c b/tools/testing/selftests/bpf/progs/tailcall_freplace.c
new file mode 100644 (file)
index 0000000..6713b80
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_freplace.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+       __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+       __uint(max_entries, 1);
+       __uint(key_size, sizeof(__u32));
+       __uint(value_size, sizeof(__u32));
+} jmp_table SEC(".maps");
+
+int count = 0;
+
+SEC("freplace")
+int entry_freplace(struct __sk_buff *skb)
+{
+       count++;
+       bpf_tail_call_static(skb, &jmp_table, 0);
+       return count;
+}
+
+char __license[] SEC("license") = "GPL";

diff --git a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c
new file mode 100644 (file)
index 0000000..8a0632c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+__noinline
+int subprog(struct __sk_buff *skb)
+{
+       int ret = 1;
+
+       __sink(ret);
+       return ret;
+}
+
+SEC("tc")
+int entry_tc(struct __sk_buff *skb)
+{
+       return subprog(skb);
+}
+
+char __license[] SEC("license") = "GPL";