bpf: Fix missing bpf_base_func_proto in cgroup_base_func_proto for CGROUP_NET=n

linux-next build bot reported compile issue [1] with one of its
configs. It looks like when we have CONFIG_NET=n and
CONFIG_BPF{,_SYSCALL}=y, we are missing the bpf_base_func_proto
definition (from net/core/filter.c) in cgroup_base_func_proto.

I'm reshuffling the code a bit to make it work. The common helpers
are moved into kernel/bpf/helpers.c and the bpf_base_func_proto is
exported from there.
Also, bpf_get_raw_cpu_id goes into kernel/bpf/core.c akin to existing
bpf_user_rnd_u32.

[1] https://lore.kernel.org/linux-next/CAKH8qBsBvKHswiX1nx40LgO+BGeTmb1NX8tiTttt_0uu6T3dCA@mail.gmail.com/T/#mff8b0c083314c68c2e2ef0211cb11bc20dc13c72

Fixes: 0456ea170c ("bpf: Enable more helpers for BPF_PROG_TYPE_CGROUP_{DEVICE,SYSCTL,SOCKOPT}")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200424235941.58382-1-sdf@google.com

kernel/bpf/core.c

@@ -2136,6 +2136,11 @@ BPF_CALL_0(bpf_user_rnd_u32)
 	return res;
 }
 
+BPF_CALL_0(bpf_get_raw_cpu_id)
+{
+	return raw_smp_processor_id();
+}
+
 /* Weak definitions of helper functions in case we don't have bpf syscall. */
 const struct bpf_func_proto bpf_map_lookup_elem_proto __weak;
 const struct bpf_func_proto bpf_map_update_elem_proto __weak;

kernel/bpf/helpers.c

@@ -562,3 +562,76 @@ const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto = {
 	.arg3_type      = ARG_PTR_TO_UNINIT_MEM,
 	.arg4_type      = ARG_CONST_SIZE,
 };
+
+static const struct bpf_func_proto bpf_get_raw_smp_processor_id_proto = {
+	.func		= bpf_get_raw_cpu_id,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+};
+
+BPF_CALL_5(bpf_event_output_data, void *, ctx, struct bpf_map *, map,
+	   u64, flags, void *, data, u64, size)
+{
+	if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
+		return -EINVAL;
+
+	return bpf_event_output(map, flags, data, size, NULL, 0, NULL);
+}
+
+const struct bpf_func_proto bpf_event_output_data_proto =  {
+	.func		= bpf_event_output_data,
+	.gpl_only       = true,
+	.ret_type       = RET_INTEGER,
+	.arg1_type      = ARG_PTR_TO_CTX,
+	.arg2_type      = ARG_CONST_MAP_PTR,
+	.arg3_type      = ARG_ANYTHING,
+	.arg4_type      = ARG_PTR_TO_MEM,
+	.arg5_type      = ARG_CONST_SIZE_OR_ZERO,
+};
+
+const struct bpf_func_proto *
+bpf_base_func_proto(enum bpf_func_id func_id)
+{
+	switch (func_id) {
+	case BPF_FUNC_map_lookup_elem:
+		return &bpf_map_lookup_elem_proto;
+	case BPF_FUNC_map_update_elem:
+		return &bpf_map_update_elem_proto;
+	case BPF_FUNC_map_delete_elem:
+		return &bpf_map_delete_elem_proto;
+	case BPF_FUNC_map_push_elem:
+		return &bpf_map_push_elem_proto;
+	case BPF_FUNC_map_pop_elem:
+		return &bpf_map_pop_elem_proto;
+	case BPF_FUNC_map_peek_elem:
+		return &bpf_map_peek_elem_proto;
+	case BPF_FUNC_get_prandom_u32:
+		return &bpf_get_prandom_u32_proto;
+	case BPF_FUNC_get_smp_processor_id:
+		return &bpf_get_raw_smp_processor_id_proto;
+	case BPF_FUNC_get_numa_node_id:
+		return &bpf_get_numa_node_id_proto;
+	case BPF_FUNC_tail_call:
+		return &bpf_tail_call_proto;
+	case BPF_FUNC_ktime_get_ns:
+		return &bpf_ktime_get_ns_proto;
+	default:
+		break;
+	}
+
+	if (!capable(CAP_SYS_ADMIN))
+		return NULL;
+
+	switch (func_id) {
+	case BPF_FUNC_spin_lock:
+		return &bpf_spin_lock_proto;
+	case BPF_FUNC_spin_unlock:
+		return &bpf_spin_unlock_proto;
+	case BPF_FUNC_trace_printk:
+		return bpf_get_trace_printk_proto();
+	case BPF_FUNC_jiffies64:
+		return &bpf_jiffies64_proto;
+	default:
+		return NULL;
+	}
+}