bpf: fix missing bpf_check_uarg_tail_zero in BPF_PROG_TEST_RUN

Commit b0b9395d ("bpf: support input __sk_buff context in
BPF_PROG_TEST_RUN") started using bpf_check_uarg_tail_zero in
BPF_PROG_TEST_RUN. However, bpf_check_uarg_tail_zero is not defined
for !CONFIG_BPF_SYSCALL:

net/bpf/test_run.c: In function ‘bpf_ctx_init’:
net/bpf/test_run.c:142:9: error: implicit declaration of function ‘bpf_check_uarg_tail_zero’ [-Werror=implicit-function-declaration]
   err = bpf_check_uarg_tail_zero(data_in, max_size, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~

Let's not build net/bpf/test_run.c when CONFIG_BPF_SYSCALL is not set.
Reported-by: kbuild test robot <lkp@intel.com>
Fixes: b0b9395d ("bpf: support input __sk_buff context in BPF_PROG_TEST_RUN")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

include/linux/bpf.h

@@ -483,14 +483,6 @@ typedef u32 (*bpf_convert_ctx_access_t)(enum bpf_access_type type,
 u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
 		     void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);
 
-int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
-			  union bpf_attr __user *uattr);
-int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
-			  union bpf_attr __user *uattr);
-int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
-				     const union bpf_attr *kattr,
-				     union bpf_attr __user *uattr);
-
 /* an array of programs to be executed under rcu_lock.
  *
  * Typical usage:
@@ -681,6 +673,13 @@ static inline int bpf_map_attr_numa_node(const union bpf_attr *attr)
 struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type);
 int array_map_alloc_check(union bpf_attr *attr);
 
+int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
+			  union bpf_attr __user *uattr);
+int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
+			  union bpf_attr __user *uattr);
+int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
+				     const union bpf_attr *kattr,
+				     union bpf_attr __user *uattr);
 #else /* !CONFIG_BPF_SYSCALL */
 static inline struct bpf_prog *bpf_prog_get(u32 ufd)
 {
@@ -792,6 +791,27 @@ static inline struct bpf_prog *bpf_prog_get_type_path(const char *name,
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
+
+static inline int bpf_prog_test_run_xdp(struct bpf_prog *prog,
+					const union bpf_attr *kattr,
+					union bpf_attr __user *uattr)
+{
+	return -ENOTSUPP;
+}
+
+static inline int bpf_prog_test_run_skb(struct bpf_prog *prog,
+					const union bpf_attr *kattr,
+					union bpf_attr __user *uattr)
+{
+	return -ENOTSUPP;
+}
+
+static inline int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
+						   const union bpf_attr *kattr,
+						   union bpf_attr __user *uattr)
+{
+	return -ENOTSUPP;
+}
 #endif /* CONFIG_BPF_SYSCALL */
 
 static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,

net/bpf/Makefile

-obj-y	:= test_run.o
+obj-$(CONFIG_BPF_SYSCALL)	:= test_run.o