selftests/bpf: check the instruction dumps are populated

Add a basic test for checking whether kernel is populating
the jited and xlated BPF images.  It was used to confirm
the behaviour change from commit d777b2ddbecf ("bpf: don't
zero out the info struct in bpf_obj_get_info_by_fd()"),
which made bpf_obj_get_info_by_fd() usable for retrieving
the image dumps.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 4 deletions

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 1cb037803679..11ee25cea227 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -279,7 +279,7 @@ static void test_bpf_obj_id(void)
         /* +1 to test for the info_len returned by kernel */
         struct bpf_prog_info prog_infos[nr_iters + 1];
         struct bpf_map_info map_infos[nr_iters + 1];
-        char jited_insns[128], xlated_insns[128];
+        char jited_insns[128], xlated_insns[128], zeros[128];
         __u32 i, next_id, info_len, nr_id_found, duration = 0;
         int sysctl_fd, jit_enabled = 0, err = 0;
         __u64 array_value;
@@ -305,6 +305,7 @@ static void test_bpf_obj_id(void)
                 objs[i] = NULL;
 
         /* Check bpf_obj_get_info_by_fd() */
+        bzero(zeros, sizeof(zeros));
         for (i = 0; i < nr_iters; i++) {
                 err = bpf_prog_load(file, BPF_PROG_TYPE_SOCKET_FILTER,
                                     &objs[i], &prog_fds[i]);
@@ -318,6 +319,8 @@ static void test_bpf_obj_id(void)
                 /* Check getting prog info */
                 info_len = sizeof(struct bpf_prog_info) * 2;
                 bzero(&prog_infos[i], info_len);
+                bzero(jited_insns, sizeof(jited_insns));
+                bzero(xlated_insns, sizeof(xlated_insns));
                 prog_infos[i].jited_prog_insns = ptr_to_u64(jited_insns);
                 prog_infos[i].jited_prog_len = sizeof(jited_insns);
                 prog_infos[i].xlated_prog_insns = ptr_to_u64(xlated_insns);
@@ -328,15 +331,20 @@ static void test_bpf_obj_id(void)
                           prog_infos[i].type != BPF_PROG_TYPE_SOCKET_FILTER ||
                           info_len != sizeof(struct bpf_prog_info) ||
                           (jit_enabled && !prog_infos[i].jited_prog_len) ||
-                          !prog_infos[i].xlated_prog_len,
+                          (jit_enabled &&
+                           !memcmp(jited_insns, zeros, sizeof(zeros))) ||
+                          !prog_infos[i].xlated_prog_len ||
+                          !memcmp(xlated_insns, zeros, sizeof(zeros)),
                           "get-prog-info(fd)",
-                          "err %d errno %d i %d type %d(%d) info_len %u(%lu) jit_enabled %d jited_prog_len %u xlated_prog_len %u\n",
+                          "err %d errno %d i %d type %d(%d) info_len %u(%lu) jit_enabled %d jited_prog_len %u xlated_prog_len %u jited_prog %d xlated_prog %d\n",
                           err, errno, i,
                           prog_infos[i].type, BPF_PROG_TYPE_SOCKET_FILTER,
                           info_len, sizeof(struct bpf_prog_info),
                           jit_enabled,
                           prog_infos[i].jited_prog_len,
-                          prog_infos[i].xlated_prog_len))
+                          prog_infos[i].xlated_prog_len,
+                          !!memcmp(jited_insns, zeros, sizeof(zeros)),
+                          !!memcmp(xlated_insns, zeros, sizeof(zeros))))
                         goto done;
 
                 map_fds[i] = bpf_find_map(__func__, objs[i], "test_map_id");