[PATCH bpf-next 5/8] xdp: add xdp_do_redirect_frame() for pre-computed xdp_frames

[Toke Høiland-Jørgensen <toke@xxxxxxxxxx>]

Add an xdp_do_redirect_frame() variant which supports pre-computed
xdp_frame structures. This will be used in bpf_prog_run() to avoid having
to write to the xdp_frame structure when the XDP program doesn't modify the
frame boundaries.

Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
---
 include/linux/filter.h |  4 ++++
 net/core/filter.c      | 28 +++++++++++++++++++++-------
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index b6a216eb217a..845452c83e0f 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1022,6 +1022,10 @@ int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb,
 int xdp_do_redirect(struct net_device *dev,
 		    struct xdp_buff *xdp,
 		    struct bpf_prog *prog);
+int xdp_do_redirect_frame(struct net_device *dev,
+			  struct xdp_buff *xdp,
+			  struct xdp_frame *xdpf,
+			  struct bpf_prog *prog);
 void xdp_do_flush(void);
 
 /* The xdp_do_flush_map() helper has been renamed to drop the _map suffix, as
diff --git a/net/core/filter.c b/net/core/filter.c
index 1e86130a913a..d8fe74cc8b66 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3957,14 +3957,13 @@ u32 xdp_master_redirect(struct xdp_buff *xdp)
 }
 EXPORT_SYMBOL_GPL(xdp_master_redirect);
 
-int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
-		    struct bpf_prog *xdp_prog)
+static int __xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
+			     struct xdp_frame *xdpf, struct bpf_prog *xdp_prog)
 {
 	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 	enum bpf_map_type map_type = ri->map_type;
 	void *fwd = ri->tgt_value;
 	u32 map_id = ri->map_id;
-	struct xdp_frame *xdpf;
 	struct bpf_map *map;
 	int err;
 
@@ -3976,10 +3975,12 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 		goto out;
 	}
 
-	xdpf = xdp_convert_buff_to_frame(xdp);
-	if (unlikely(!xdpf)) {
-		err = -EOVERFLOW;
-		goto err;
+	if (!xdpf) {
+		xdpf = xdp_convert_buff_to_frame(xdp);
+		if (unlikely(!xdpf)) {
+			err = -EOVERFLOW;
+			goto err;
+		}
 	}
 
 	switch (map_type) {
@@ -4024,8 +4025,21 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 	_trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map_type, map_id, ri->tgt_index, err);
 	return err;
 }
+
+int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
+		    struct bpf_prog *xdp_prog)
+{
+	return __xdp_do_redirect(dev, xdp, NULL, xdp_prog);
+}
 EXPORT_SYMBOL_GPL(xdp_do_redirect);
 
+int xdp_do_redirect_frame(struct net_device *dev, struct xdp_buff *xdp,
+			  struct xdp_frame *xdpf, struct bpf_prog *xdp_prog)
+{
+	return __xdp_do_redirect(dev, xdp, xdpf, xdp_prog);
+}
+EXPORT_SYMBOL_GPL(xdp_do_redirect_frame);
+
 static int xdp_do_generic_redirect_map(struct net_device *dev,
 				       struct sk_buff *skb,
 				       struct xdp_buff *xdp,
-- 
2.34.0