bpf: XDP metadata RX kfuncs

Define a new kfunc set (xdp_metadata_kfunc_ids) which implements all possible
XDP metatada kfuncs. Not all devices have to implement them. If kfunc is not
supported by the target device, the default implementation is called instead.
The verifier, at load time, replaces a call to the generic kfunc with a call
to the per-device one. Per-device kfunc pointers are stored in separate
struct xdp_metadata_ops.

Cc: John Fastabend <john.fastabend@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Anatoly Burakov <anatoly.burakov@intel.com>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: Maryam Tahhan <mtahhan@redhat.com>
Cc: xdp-hints@xdp-project.net
Cc: netdev@vger.kernel.org
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230119221536.3349901-8-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

2 files changed, 67 insertions, 0 deletions

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 2723623429ac..8da0d73b368e 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -1300,6 +1300,9 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 	if (kattr->test.flags & ~BPF_F_TEST_XDP_LIVE_FRAMES)
 		return -EINVAL;
 
+	if (bpf_prog_is_dev_bound(prog->aux))
+		return -EINVAL;
+
 	if (do_live) {
 		if (!batch_size)
 			batch_size = NAPI_POLL_WEIGHT;
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 844c9d99dc0e..a5a7ecf6391c 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -4,6 +4,7 @@
  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
  */
 #include <linux/bpf.h>
+#include <linux/btf_ids.h>
 #include <linux/filter.h>
 #include <linux/types.h>
 #include <linux/mm.h>
@@ -709,3 +710,66 @@ struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf)
 
 	return nxdpf;
 }
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+		  "Global functions as their definitions will be in vmlinux BTF");
+
+/**
+ * bpf_xdp_metadata_rx_timestamp - Read XDP frame RX timestamp.
+ * @ctx: XDP context pointer.
+ * @timestamp: Return value pointer.
+ *
+ * Returns 0 on success or ``-errno`` on error.
+ */
+int bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx, u64 *timestamp)
+{
+	return -EOPNOTSUPP;
+}
+
+/**
+ * bpf_xdp_metadata_rx_hash - Read XDP frame RX hash.
+ * @ctx: XDP context pointer.
+ * @hash: Return value pointer.
+ *
+ * Returns 0 on success or ``-errno`` on error.
+ */
+int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, u32 *hash)
+{
+	return -EOPNOTSUPP;
+}
+
+__diag_pop();
+
+BTF_SET8_START(xdp_metadata_kfunc_ids)
+#define XDP_METADATA_KFUNC(_, name) BTF_ID_FLAGS(func, name, 0)
+XDP_METADATA_KFUNC_xxx
+#undef XDP_METADATA_KFUNC
+BTF_SET8_END(xdp_metadata_kfunc_ids)
+
+static const struct btf_kfunc_id_set xdp_metadata_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &xdp_metadata_kfunc_ids,
+};
+
+BTF_ID_LIST(xdp_metadata_kfunc_ids_unsorted)
+#define XDP_METADATA_KFUNC(name, str) BTF_ID(func, str)
+XDP_METADATA_KFUNC_xxx
+#undef XDP_METADATA_KFUNC
+
+u32 bpf_xdp_metadata_kfunc_id(int id)
+{
+	/* xdp_metadata_kfunc_ids is sorted and can't be used */
+	return xdp_metadata_kfunc_ids_unsorted[id];
+}
+
+bool bpf_dev_bound_kfunc_id(u32 btf_id)
+{
+	return btf_id_set8_contains(&xdp_metadata_kfunc_ids, btf_id);
+}
+
+static int __init xdp_metadata_init(void)
+{
+	return register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &xdp_metadata_kfunc_set);
+}
+late_initcall(xdp_metadata_init);