kernel: 5.4: import wireguard backport

Rather than using the clunky, old, slower wireguard-linux-compat out of
tree module, this commit does a patch-by-patch backport of upstream's
wireguard to 5.4. This specific backport is in widespread use, being
part of SUSE's enterprise kernel, Oracle's enterprise kernel, Google's
Android kernel, Gentoo's distro kernel, and probably more I've forgotten
about. It's definately the "more proper" way of adding wireguard to a
kernel than the ugly compat.h hell of the wireguard-linux-compat repo.
And most importantly for OpenWRT, it allows using the same module
configuration code for 5.10 as for 5.4, with no need for bifurcation.

These patches are from the backport tree which is maintained in the
open here: https://git.zx2c4.com/wireguard-linux/log/?h=backport-5.4.y
I'll be sending PRs to update this as needed.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0118-wireguard-avoid-double-unlikely-notation-when-using-.patch b/target/linux/generic/backport-5.4/080-wireguard-0118-wireguard-avoid-double-unlikely-notation-when-using-.patch
new file mode 100644
index 0000000000..b461b771dd
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0118-wireguard-avoid-double-unlikely-notation-when-using-.patch
@@ -0,0 +1,55 @@
+From 6f5f2660a44325a75ff2ccbf799103c3613e78bb Mon Sep 17 00:00:00 2001
+From: Antonio Quartulli <a@unstable.cc>
+Date: Mon, 22 Feb 2021 17:25:43 +0100
+Subject: [PATCH 118/124] wireguard: avoid double unlikely() notation when
+ using IS_ERR()
+
+commit 30ac4e2f54ec067b7b9ca0db27e75681581378d6 upstream.
+
+The definition of IS_ERR() already applies the unlikely() notation
+when checking the error status of the passed pointer. For this
+reason there is no need to have the same notation outside of
+IS_ERR() itself.
+
+Clean up code by removing redundant notation.
+
+Signed-off-by: Antonio Quartulli <a@unstable.cc>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+---
+ drivers/net/wireguard/device.c | 2 +-
+ drivers/net/wireguard/socket.c | 4 ++--
+ 2 files changed, 3 insertions(+), 3 deletions(-)
+
+--- a/drivers/net/wireguard/device.c
++++ b/drivers/net/wireguard/device.c
+@@ -157,7 +157,7 @@ static netdev_tx_t wg_xmit(struct sk_buf
+ 	} else {
+ 		struct sk_buff *segs = skb_gso_segment(skb, 0);
+ 
+-		if (unlikely(IS_ERR(segs))) {
++		if (IS_ERR(segs)) {
+ 			ret = PTR_ERR(segs);
+ 			goto err_peer;
+ 		}
+--- a/drivers/net/wireguard/socket.c
++++ b/drivers/net/wireguard/socket.c
+@@ -71,7 +71,7 @@ static int send4(struct wg_device *wg, s
+ 				ip_rt_put(rt);
+ 			rt = ip_route_output_flow(sock_net(sock), &fl, sock);
+ 		}
+-		if (unlikely(IS_ERR(rt))) {
++		if (IS_ERR(rt)) {
+ 			ret = PTR_ERR(rt);
+ 			net_dbg_ratelimited("%s: No route to %pISpfsc, error %d\n",
+ 					    wg->dev->name, &endpoint->addr, ret);
+@@ -138,7 +138,7 @@ static int send6(struct wg_device *wg, s
+ 		}
+ 		dst = ipv6_stub->ipv6_dst_lookup_flow(sock_net(sock), sock, &fl,
+ 						      NULL);
+-		if (unlikely(IS_ERR(dst))) {
++		if (IS_ERR(dst)) {
+ 			ret = PTR_ERR(dst);
+ 			net_dbg_ratelimited("%s: No route to %pISpfsc, error %d\n",
+ 					    wg->dev->name, &endpoint->addr, ret);