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, 42 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0121-wireguard-peer-put-frequently-used-members-above-cac.patch b/target/linux/generic/backport-5.4/080-wireguard-0121-wireguard-peer-put-frequently-used-members-above-cac.patch
new file mode 100644
index 0000000000..bd4fd77380
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0121-wireguard-peer-put-frequently-used-members-above-cac.patch
@@ -0,0 +1,42 @@
+From a13827e9091c07e25cdeec9a402d74a27e2a1111 Mon Sep 17 00:00:00 2001
+From: "Jason A. Donenfeld" <Jason@zx2c4.com>
+Date: Mon, 22 Feb 2021 17:25:46 +0100
+Subject: [PATCH 121/124] wireguard: peer: put frequently used members above
+ cache lines
+
+commit 5a0598695634a6bb4126818902dd9140cd9df8b6 upstream.
+
+The is_dead boolean is checked for every single packet, while the
+internal_id member is used basically only for pr_debug messages. So it
+makes sense to hoist up is_dead into some space formerly unused by a
+struct hole, while demoting internal_api to below the lowest struct
+cache line.
+
+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/peer.h | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/drivers/net/wireguard/peer.h
++++ b/drivers/net/wireguard/peer.h
+@@ -39,6 +39,7 @@ struct wg_peer {
+ 	struct crypt_queue tx_queue, rx_queue;
+ 	struct sk_buff_head staged_packet_queue;
+ 	int serial_work_cpu;
++	bool is_dead;
+ 	struct noise_keypairs keypairs;
+ 	struct endpoint endpoint;
+ 	struct dst_cache endpoint_cache;
+@@ -61,9 +62,8 @@ struct wg_peer {
+ 	struct rcu_head rcu;
+ 	struct list_head peer_list;
+ 	struct list_head allowedips_list;
+-	u64 internal_id;
+ 	struct napi_struct napi;
+-	bool is_dead;
++	u64 internal_id;
+ };
+ 
+ struct wg_peer *wg_peer_create(struct wg_device *wg,