compat: backport to FreeBSD 12.2

This should allow us to get more testing coverage earlier.

This port here is also a bit janky. I really don't like the taskqgroup
business, having to copy and paste those structs. And this isn't well
tested, either. But, it's a start.

This distinguishes between compat.h and support.h, though both header
files are intended to operate in more or less the same way.  It's
important to keep some discipline between things that we're backporting
and things that aren't _yet_ upstream or are shims for OpenBSD.

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

8 files changed, 97 insertions, 31 deletions

diff --git a/MISSING.md b/MISSING.md
index 4a75f50..e688bb4 100644
--- a/MISSING.md
+++ b/MISSING.md
@@ -6,4 +6,4 @@ There are a few changes that we had in-tree that we now don't, and will need to
 - The `PRIV_NET_WG` privilege.
 - `sogetsockaddr` helper function, which belongs in `uipc_socket.c`.
 
-We're emulating these in support.h/support.c, but they should go away for the merge.
+We're emulating these in support.h, but they should go away for the merge.
diff --git a/README.md b/README.md
index 5596904..8b526c5 100644
--- a/README.md
+++ b/README.md
@@ -6,14 +6,11 @@ This is a kernel module for FreeBSD to support [WireGuard](https://www.wireguard
 
 First make sure you have the latest net/wireguard package installed, version ≥1.0.20210315.
 
-Then, on FreeBSD 13.0:
+Then, on FreeBSD 12 & 13:
 
 ```
-# pkg install wireguard
 # git clone https://git.zx2c4.com/wireguard-freebsd
-# cd wireguard-freebsd/src
-# make load
-# make install
+# make -C wireguard-freebsd/src load install
 ```
 
 After that, it should be possible to use `wg(8)` and `wg-quick(8)` like usual, but with the faster kernel implementation.
diff --git a/src/Makefile b/src/Makefile
index c024ea1..e787882 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,9 +1,11 @@
 # $FreeBSD$
 
-KMOD=   if_wg
+KMOD= if_wg
 
 SRCS= opt_inet.h opt_inet6.h device_if.h bus_if.h ifdi_if.h
 
-SRCS+= if_wg.c wg_noise.c wg_cookie.c crypto.c support.c
+SRCS+= if_wg.c wg_noise.c wg_cookie.c crypto.c
+
+CFLAGS+= -include compat.h
 
 .include <bsd.kmod.mk>
diff --git a/src/compat.h b/src/compat.h
new file mode 100644
index 0000000..649e7dc
--- /dev/null
+++ b/src/compat.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2021 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ *
+ * compat.h contains functions that are backported from FreeBSD's main branch. It is different from
+ * support.h, which is for things that aren't _yet_ upstream or from OpenBSD.
+ */
+
+#include <sys/param.h>
+#if __FreeBSD_version < 1300000
+#define VIMAGE
+
+#include <sys/types.h>
+#include <sys/limits.h>
+#include <sys/endian.h>
+#include <sys/socket.h>
+#include <sys/libkern.h>
+#include <sys/malloc.h>
+#include <sys/proc.h>
+#include <sys/lock.h>
+#include <sys/smp.h>
+#include <sys/gtaskqueue.h>
+#include <sys/socketvar.h>
+#include <sys/protosw.h>
+#include <net/vnet.h>
+#include <net/if.h>
+#include <net/if_var.h>
+#include <vm/uma.h>
+
+#define taskqgroup_attach(a, b, c, d, e, f) taskqgroup_attach((a), (b), (c), -1, (f))
+#define taskqgroup_attach_cpu(a, b, c, d, e, f, g) taskqgroup_attach_cpu((a), (b), (c), (d), -1, (g))
+
+#undef NET_EPOCH_ENTER
+#define NET_EPOCH_ENTER(et) NET_EPOCH_ENTER_ET(et)
+#undef NET_EPOCH_EXIT
+#define NET_EPOCH_EXIT(et) NET_EPOCH_EXIT_ET(et)
+#define NET_EPOCH_CALL(f, c) epoch_call(net_epoch_preempt, (c), (f))
+#define NET_EPOCH_ASSERT() MPASS(in_epoch(net_epoch_preempt))
+
+#undef atomic_load_ptr
+#define atomic_load_ptr(p) (*(volatile __typeof(*p) *)(p))
+
+struct taskqgroup_cpu {
+	LIST_HEAD(, grouptask)	tgc_tasks;
+	struct gtaskqueue	*tgc_taskq;
+	int	tgc_cnt;
+	int	tgc_cpu;
+};
+
+struct taskqgroup {
+	struct taskqgroup_cpu tqg_queue[MAXCPU];
+	struct mtx	tqg_lock;
+	const char *	tqg_name;
+	int		tqg_adjusting;
+	int		tqg_stride;
+	int		tqg_cnt;
+};
+
+static inline void taskqgroup_drain_all(struct taskqgroup *tqg)
+{
+	struct gtaskqueue *q;
+
+	for (int i = 0; i < mp_ncpus; i++) {
+		q = tqg->tqg_queue[i].tgc_taskq;
+		if (q == NULL)
+			continue;
+		gtaskqueue_drain_all(q);
+	}
+}
+
+#endif
diff --git a/src/support.c b/src/support.c
deleted file mode 100644
index 18ce91b..0000000
--- a/src/support.c
+++ /dev/null
@@ -1,20 +0,0 @@
-/* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
- *
- * Copyright (C) 2015-2021 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
- */
-
-#include "support.h"
-#include <sys/socketvar.h>
-#include <sys/protosw.h>
-#include <net/vnet.h>
-
-int
-sogetsockaddr(struct socket *so, struct sockaddr **nam)
-{
-	int error;
-
-	CURVNET_SET(so->so_vnet);
-	error = (*so->so_proto->pr_usrreqs->pru_sockaddr)(so, nam);
-	CURVNET_RESTORE();
-	return (error);
-}
diff --git a/src/support.h b/src/support.h
index c4038cf..5256e62 100644
--- a/src/support.h
+++ b/src/support.h
@@ -2,6 +2,9 @@
  *
  * Copyright (C) 2021 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
  * Copyright (C) 2021 Matt Dunwoodie <ncon@noconroy.net>
+ *
+ * support.h contains functions that are either not _yet_ upstream in FreeBSD 14, or are shimmed
+ * from OpenBSD. It is different from compat.h, which is strictly for backports.
  */
 
 #ifndef _WG_SUPPORT
@@ -15,6 +18,9 @@
 #include <sys/malloc.h>
 #include <sys/proc.h>
 #include <sys/lock.h>
+#include <sys/socketvar.h>
+#include <sys/protosw.h>
+#include <net/vnet.h>
 #include <vm/uma.h>
 
 /* TODO the following is openbsd compat defines to allow us to copy the wg_*
@@ -65,7 +71,15 @@ siphash24(const SIPHASH_KEY *key, const void *src, size_t len)
 #define IFT_WIREGUARD IFT_PPP
 #endif
 
-int
-sogetsockaddr(struct socket *so, struct sockaddr **nam);
+static inline int
+sogetsockaddr(struct socket *so, struct sockaddr **nam)
+{
+	int error;
+
+	CURVNET_SET(so->so_vnet);
+	error = (*so->so_proto->pr_usrreqs->pru_sockaddr)(so, nam);
+	CURVNET_RESTORE();
+	return (error);
+}
 
 #endif
diff --git a/src/wg_cookie.c b/src/wg_cookie.c
index bf0ce37..ab35ad4 100644
--- a/src/wg_cookie.c
+++ b/src/wg_cookie.c
@@ -7,6 +7,7 @@
 #include <sys/types.h>
 #include <sys/systm.h>
 #include <sys/param.h>
+#include <sys/lock.h>
 #include <sys/rwlock.h>
 #include <sys/malloc.h> /* Because systm doesn't include M_NOWAIT, M_DEVBUF */
 #include <sys/socket.h>
diff --git a/src/wg_noise.c b/src/wg_noise.c
index 42dcc87..23603f0 100644
--- a/src/wg_noise.c
+++ b/src/wg_noise.c
@@ -5,9 +5,10 @@
  */
 
 #include <sys/types.h>
-#include <sys/systm.h>
 #include <sys/param.h>
+#include <sys/lock.h>
 #include <sys/rwlock.h>
+#include <sys/systm.h>
 
 #include "support.h"
 #include "wg_noise.h"