Merge tag 'for-linus-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

Pull UML updates from Richard Weinberger:

 - virtio support

 - fixes for our new time travel mode

 - various improvements to make lockdep and kasan work better

 - SPDX header updates

* tag 'for-linus-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: (25 commits)
  um: irq: Fix LAST_IRQ usage in init_IRQ()
  um: Add SPDX headers for files in arch/um/include
  um: Add SPDX headers for files in arch/um/os-Linux
  um: Add SPDX headers to files in arch/um/kernel/
  um: Add SPDX headers for files in arch/um/drivers
  um: virtio: Implement VHOST_USER_PROTOCOL_F_REPLY_ACK
  um: virtio: Implement VHOST_USER_PROTOCOL_F_SLAVE_REQ
  um: drivers: Add virtio vhost-user driver
  um: Use real DMA barriers
  um: Don't use generic barrier.h
  um: time-travel: Restrict time update in IRQ handler
  um: time-travel: Fix periodic timers
  um: Enable CONFIG_CONSTRUCTORS
  um: Place (soft)irq text with macros
  um: Fix VDSO compiler warning
  um: Implement TRACE_IRQFLAGS_SUPPORT
  um: Remove misleading #define ARCh_IRQ_ENABLED
  um: Avoid using uninitialized regs
  um: Remove sig_info[SIGALRM]
  um: Error handling fixes in vector drivers
  ...

154 files changed, 1913 insertions, 291 deletions

diff --git a/arch/um/drivers/Kconfig b/arch/um/drivers/Kconfig
index 2638e46f50cc..fea5a0d522dc 100644
--- a/arch/um/drivers/Kconfig
+++ b/arch/um/drivers/Kconfig
@@ -335,3 +335,10 @@ config UML_NET_SLIRP
 	  Startup example: "eth0=slirp,FE:FD:01:02:03:04,/usr/local/bin/slirp"
 
 endmenu
+
+config VIRTIO_UML
+	tristate "UML driver for virtio devices"
+	select VIRTIO
+	help
+	  This driver provides support for virtio based paravirtual device
+	  drivers over vhost-user sockets.
diff --git a/arch/um/drivers/Makefile b/arch/um/drivers/Makefile
index 693319839f69..a290821e355c 100644
--- a/arch/um/drivers/Makefile
+++ b/arch/um/drivers/Makefile
@@ -1,6 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
 # 
 # Copyright (C) 2000, 2002, 2003 Jeff Dike (jdike@karaya.com)
-# Licensed under the GPL
 #
 
 # pcap is broken in 2.5 because kbuild doesn't allow pcap.a to be linked
@@ -61,6 +61,7 @@ obj-$(CONFIG_XTERM_CHAN) += xterm.o xterm_kern.o
 obj-$(CONFIG_UML_WATCHDOG) += harddog.o
 obj-$(CONFIG_BLK_DEV_COW_COMMON) += cow_user.o
 obj-$(CONFIG_UML_RANDOM) += random.o
+obj-$(CONFIG_VIRTIO_UML) += virtio_uml.o
 
 # pcap_user.o must be added explicitly.
 USER_OBJS := fd.o null.o pty.o tty.o xterm.o slip_common.o pcap_user.o vde_user.o vector_user.o
diff --git a/arch/um/drivers/chan.h b/arch/um/drivers/chan.h
index c512b0306dd4..c37cc4f26f91 100644
--- a/arch/um/drivers/chan.h
+++ b/arch/um/drivers/chan.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __CHAN_KERN_H__
diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c
index 749d2bf59599..62997055c454 100644
--- a/arch/um/drivers/chan_kern.c
+++ b/arch/um/drivers/chan_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 #include <linux/slab.h>
diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c
index 3fd7c3efdb18..4d80526a4236 100644
--- a/arch/um/drivers/chan_user.c
+++ b/arch/um/drivers/chan_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 #include <stdlib.h>
diff --git a/arch/um/drivers/chan_user.h b/arch/um/drivers/chan_user.h
index 03f1b565c5f9..72222bb036f5 100644
--- a/arch/um/drivers/chan_user.h
+++ b/arch/um/drivers/chan_user.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __CHAN_USER_H__
diff --git a/arch/um/drivers/cow_user.c b/arch/um/drivers/cow_user.c
index 0ee9cc6cc4c7..74b0c2686c95 100644
--- a/arch/um/drivers/cow_user.c
+++ b/arch/um/drivers/cow_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 /*
diff --git a/arch/um/drivers/daemon.h b/arch/um/drivers/daemon.h
index c2dd1951559f..1509cc7eb907 100644
--- a/arch/um/drivers/daemon.h
+++ b/arch/um/drivers/daemon.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __DAEMON_H__
diff --git a/arch/um/drivers/daemon_kern.c b/arch/um/drivers/daemon_kern.c
index 7568cc2f3cd6..fd2402669c49 100644
--- a/arch/um/drivers/daemon_kern.c
+++ b/arch/um/drivers/daemon_kern.c
@@ -1,9 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright (C) 2001 by various other people who didn't put their name here.
- * Licensed under the GPL.
  */
 
 #include <linux/init.h>
diff --git a/arch/um/drivers/daemon_user.c b/arch/um/drivers/daemon_user.c
index 8813c10d0177..3695821d06a2 100644
--- a/arch/um/drivers/daemon_user.c
+++ b/arch/um/drivers/daemon_user.c
@@ -1,9 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 by various other people who didn't put their name here.
- * Licensed under the GPL.
  */
 
 #include <stdint.h>
diff --git a/arch/um/drivers/fd.c b/arch/um/drivers/fd.c
index a13a427b996b..082d739dc052 100644
--- a/arch/um/drivers/fd.c
+++ b/arch/um/drivers/fd.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/drivers/harddog_user.c b/arch/um/drivers/harddog_user.c
index 3aa8b0d52a48..070468d22e39 100644
--- a/arch/um/drivers/harddog_user.c
+++ b/arch/um/drivers/harddog_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/drivers/hostaudio_kern.c b/arch/um/drivers/hostaudio_kern.c
index 7f9dbdbc4eb7..bf75b1ceac47 100644
--- a/arch/um/drivers/hostaudio_kern.c
+++ b/arch/um/drivers/hostaudio_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 Steve Schmidtke
- * Licensed under the GPL
  */
 
 #include <linux/fs.h>
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index e0e63931fb2b..4f2a4ac8a82b 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/irqreturn.h>
diff --git a/arch/um/drivers/line.h b/arch/um/drivers/line.h
index 138a14526d9c..a151ff5155ef 100644
--- a/arch/um/drivers/line.h
+++ b/arch/um/drivers/line.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __LINE_H__
diff --git a/arch/um/drivers/mconsole.h b/arch/um/drivers/mconsole.h
index 44af7379ea19..6356378304fd 100644
--- a/arch/um/drivers/mconsole.h
+++ b/arch/um/drivers/mconsole.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __MCONSOLE_H__
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index ff3ab72fd90f..0117489e9b30 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
  * Copyright (C) 2001 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/console.h>
diff --git a/arch/um/drivers/mconsole_kern.h b/arch/um/drivers/mconsole_kern.h
index 7a0c6a1ad1d4..56d8d6a3ff76 100644
--- a/arch/um/drivers/mconsole_kern.h
+++ b/arch/um/drivers/mconsole_kern.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __MCONSOLE_KERN_H__
diff --git a/arch/um/drivers/mconsole_user.c b/arch/um/drivers/mconsole_user.c
index 99209826adb1..e24298a734be 100644
--- a/arch/um/drivers/mconsole_user.c
+++ b/arch/um/drivers/mconsole_user.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <errno.h>
diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index 6e5be5fb4143..327b728f7244 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -1,9 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 by various other people who didn't put their name here.
- * Licensed under the GPL.
  */
 
 #include <linux/memblock.h>
diff --git a/arch/um/drivers/net_user.c b/arch/um/drivers/net_user.c
index e9f8445861dc..4c9576452ab0 100644
--- a/arch/um/drivers/net_user.c
+++ b/arch/um/drivers/net_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/drivers/null.c b/arch/um/drivers/null.c
index 10495747ce8e..87087763a417 100644
--- a/arch/um/drivers/null.c
+++ b/arch/um/drivers/null.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 #include <stddef.h>
diff --git a/arch/um/drivers/pcap_kern.c b/arch/um/drivers/pcap_kern.c
index be0fb57bd1d7..cfe4cb17694c 100644
--- a/arch/um/drivers/pcap_kern.c
+++ b/arch/um/drivers/pcap_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL.
  */
 
 #include <linux/init.h>
diff --git a/arch/um/drivers/pcap_user.c b/arch/um/drivers/pcap_user.c
index c07b9c752c86..bbd20638788a 100644
--- a/arch/um/drivers/pcap_user.c
+++ b/arch/um/drivers/pcap_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL.
  */
 
 #include <errno.h>
diff --git a/arch/um/drivers/pcap_user.h b/arch/um/drivers/pcap_user.h
index 1ca7c764cc63..216246f5f09b 100644
--- a/arch/um/drivers/pcap_user.h
+++ b/arch/um/drivers/pcap_user.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #include <net_user.h>
diff --git a/arch/um/drivers/port.h b/arch/um/drivers/port.h
index 372a80c0556a..9085b336e683 100644
--- a/arch/um/drivers/port.h
+++ b/arch/um/drivers/port.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2001 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __PORT_H__
diff --git a/arch/um/drivers/port_kern.c b/arch/um/drivers/port_kern.c
index b0e9ff35daee..a47ca5376d9d 100644
--- a/arch/um/drivers/port_kern.c
+++ b/arch/um/drivers/port_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 #include <linux/completion.h>
diff --git a/arch/um/drivers/port_user.c b/arch/um/drivers/port_user.c
index 5f56d11b886f..5b5b64cb1071 100644
--- a/arch/um/drivers/port_user.c
+++ b/arch/um/drivers/port_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/drivers/pty.c b/arch/um/drivers/pty.c
index f1fcc2cedb5e..39c60068cfdf 100644
--- a/arch/um/drivers/pty.c
+++ b/arch/um/drivers/pty.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/drivers/slip_kern.c b/arch/um/drivers/slip_kern.c
index ed5249fc0574..c58ccdcc16d6 100644
--- a/arch/um/drivers/slip_kern.c
+++ b/arch/um/drivers/slip_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL.
  */
 
 #include <linux/if_arp.h>
diff --git a/arch/um/drivers/slip_user.c b/arch/um/drivers/slip_user.c
index 0d6b66c64a81..8016d32b6809 100644
--- a/arch/um/drivers/slip_user.c
+++ b/arch/um/drivers/slip_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL.
  */
 
 #include <stdio.h>
diff --git a/arch/um/drivers/slirp_kern.c b/arch/um/drivers/slirp_kern.c
index 4ef11ca7cacf..2d9769237f08 100644
--- a/arch/um/drivers/slirp_kern.c
+++ b/arch/um/drivers/slirp_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL.
  */
 
 #include <linux/if_arp.h>
diff --git a/arch/um/drivers/slirp_user.c b/arch/um/drivers/slirp_user.c
index 98b6a41a254e..8f633e2e5f3d 100644
--- a/arch/um/drivers/slirp_user.c
+++ b/arch/um/drivers/slirp_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL.
  */
 
 #include <unistd.h>
diff --git a/arch/um/drivers/ssl.c b/arch/um/drivers/ssl.c
index 7ae407d5337e..b213201b8a3b 100644
--- a/arch/um/drivers/ssl.c
+++ b/arch/um/drivers/ssl.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /* 
  * Copyright (C) 2000, 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #include <linux/fs.h>
diff --git a/arch/um/drivers/stdio_console.c b/arch/um/drivers/stdio_console.c
index c90817b04da9..0021d7ffb528 100644
--- a/arch/um/drivers/stdio_console.c
+++ b/arch/um/drivers/stdio_console.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /* 
  * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #include <linux/posix_types.h>
diff --git a/arch/um/drivers/stdio_console.h b/arch/um/drivers/stdio_console.h
index 6d8275f71fd4..3a409ec23d63 100644
--- a/arch/um/drivers/stdio_console.h
+++ b/arch/um/drivers/stdio_console.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __STDIO_CONSOLE_H
diff --git a/arch/um/drivers/tty.c b/arch/um/drivers/tty.c
index eaa201bca5ed..884a762d21c7 100644
--- a/arch/um/drivers/tty.c
+++ b/arch/um/drivers/tty.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 #include <errno.h>
diff --git a/arch/um/drivers/ubd.h b/arch/um/drivers/ubd.h
index cc1cc85f5afc..f016fe15499f 100644
--- a/arch/um/drivers/ubd.h
+++ b/arch/um/drivers/ubd.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
  * Copyright (C) 2001 RidgeRun, Inc (glonnon@ridgerun.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_UBD_USER_H
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 33c1cd6a12ac..612535cd9706 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -1,8 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2018 Cambridge Greys Ltd
  * Copyright (C) 2015-2016 Anton Ivanov (aivanov@brocade.com)
  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 /* 2001-09-28...2002-04-17
diff --git a/arch/um/drivers/ubd_user.c b/arch/um/drivers/ubd_user.c
index 6f744794d141..a1afe414ce48 100644
--- a/arch/um/drivers/ubd_user.c
+++ b/arch/um/drivers/ubd_user.c
@@ -1,8 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2016 Anton Ivanov (aivanov@brocade.com)
  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
  * Copyright (C) 2001 Ridgerun,Inc (glonnon@ridgerun.com)
- * Licensed under the GPL
  */
 
 #include <stddef.h>
diff --git a/arch/um/drivers/umcast.h b/arch/um/drivers/umcast.h
index c190c6440911..fe39bee1e3bd 100644
--- a/arch/um/drivers/umcast.h
+++ b/arch/um/drivers/umcast.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __DRIVERS_UMCAST_H
diff --git a/arch/um/drivers/umcast_kern.c b/arch/um/drivers/umcast_kern.c
index f5ba6e377913..595a54f2b9c6 100644
--- a/arch/um/drivers/umcast_kern.c
+++ b/arch/um/drivers/umcast_kern.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * user-mode-linux networking multicast transport
  * Copyright (C) 2001 by Harald Welte <laforge@gnumonks.org>
@@ -8,7 +9,6 @@
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 by various other people who didn't put their name here.
  *
- * Licensed under the GPL.
  */
 
 #include <linux/init.h>
diff --git a/arch/um/drivers/umcast_user.c b/arch/um/drivers/umcast_user.c
index 6074184bb51b..b50b13cff04e 100644
--- a/arch/um/drivers/umcast_user.c
+++ b/arch/um/drivers/umcast_user.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * user-mode-linux networking multicast transport
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
@@ -8,7 +9,6 @@
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 by various other people who didn't put their name here.
  *
- * Licensed under the GPL.
  *
  */
 
diff --git a/arch/um/drivers/vde.h b/arch/um/drivers/vde.h
index fc3a05902ba1..cab0379e6142 100644
--- a/arch/um/drivers/vde.h
+++ b/arch/um/drivers/vde.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2007 Luca Bigliardi (shammash@artha.org).
- * Licensed under the GPL.
  */
 
 #ifndef __UM_VDE_H__
diff --git a/arch/um/drivers/vde_kern.c b/arch/um/drivers/vde_kern.c
index 6a365fadc7c4..bc6f22cbfb35 100644
--- a/arch/um/drivers/vde_kern.c
+++ b/arch/um/drivers/vde_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Luca Bigliardi (shammash@artha.org).
- * Licensed under the GPL.
  *
  * Transport usage:
  *  ethN=vde,<vde_switch>,<mac addr>,<port>,<group>,<mode>,<description>
diff --git a/arch/um/drivers/vde_user.c b/arch/um/drivers/vde_user.c
index 64cb630d1157..bc7dc4e1e486 100644
--- a/arch/um/drivers/vde_user.c
+++ b/arch/um/drivers/vde_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Luca Bigliardi (shammash@artha.org).
- * Licensed under the GPL.
  */
 
 #include <stddef.h>
diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index e190e4ca52e1..769ffbd9e9a6 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2017 - Cambridge Greys Limited
  * Copyright (C) 2011 - 2014 Cisco Systems Inc
@@ -5,7 +6,6 @@
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 by various other people who didn't put their name here.
- * Licensed under the GPL.
  */
 
 #include <linux/version.h>
@@ -76,6 +76,7 @@ static void vector_eth_configure(int n, struct arglist *def);
 #define DEFAULT_VECTOR_SIZE 64
 #define TX_SMALL_PACKET 128
 #define MAX_IOV_SIZE (MAX_SKB_FRAGS + 1)
+#define MAX_ITERATIONS 64
 
 static const struct {
 	const char string[ETH_GSTRING_LEN];
@@ -121,7 +122,8 @@ static int get_mtu(struct arglist *def)
 
 	if (mtu != NULL) {
 		if (kstrtoul(mtu, 10, &result) == 0)
-			return result;
+			if ((result < (1 << 16) - 1) && (result >= 576))
+				return result;
 	}
 	return ETH_MAX_PACKET;
 }
@@ -186,6 +188,8 @@ static int get_transport_options(struct arglist *def)
 
 
 	if (strncmp(transport, TRANS_TAP, TRANS_TAP_LEN) == 0)
+		return 0;
+	if (strncmp(transport, TRANS_HYBRID, TRANS_HYBRID_LEN) == 0)
 		return (vec_rx | VECTOR_BPF);
 	if (strncmp(transport, TRANS_RAW, TRANS_RAW_LEN) == 0)
 		return (vec_rx | vec_tx | VECTOR_QDISC_BYPASS);
@@ -415,6 +419,7 @@ static int vector_send(struct vector_queue *qi)
 					if (net_ratelimit())
 						netdev_err(vp->dev, "sendmmsg err=%i\n",
 							result);
+					vp->in_error = true;
 					result = send_len;
 				}
 				if (result > 0) {
@@ -842,6 +847,10 @@ static int vector_legacy_rx(struct vector_private *vp)
 	}
 
 	pkt_len = uml_vector_recvmsg(vp->fds->rx_fd, &hdr, 0);
+	if (pkt_len < 0) {
+		vp->in_error = true;
+		return pkt_len;
+	}
 
 	if (skb != NULL) {
 		if (pkt_len > vp->header_size) {
@@ -888,12 +897,16 @@ static int writev_tx(struct vector_private *vp, struct sk_buff *skb)
 
 	if (iov_count < 1)
 		goto drop;
+
 	pkt_len = uml_vector_writev(
 		vp->fds->tx_fd,
 		(struct iovec *) &iov,
 		iov_count
 	);
 
+	if (pkt_len < 0)
+		goto drop;
+
 	netif_trans_update(vp->dev);
 	netif_wake_queue(vp->dev);
 
@@ -908,6 +921,8 @@ static int writev_tx(struct vector_private *vp, struct sk_buff *skb)
 drop:
 	vp->dev->stats.tx_dropped++;
 	consume_skb(skb);
+	if (pkt_len < 0)
+		vp->in_error = true;
 	return pkt_len;
 }
 
@@ -936,6 +951,9 @@ static int vector_mmsg_rx(struct vector_private *vp)
 	packet_count = uml_vector_recvmmsg(
 		vp->fds->rx_fd, qi->mmsg_vector, qi->max_depth, 0);
 
+	if (packet_count < 0)
+		vp->in_error = true;
+
 	if (packet_count <= 0)
 		return packet_count;
 
@@ -1005,15 +1023,18 @@ static int vector_mmsg_rx(struct vector_private *vp)
 static void vector_rx(struct vector_private *vp)
 {
 	int err;
+	int iter = 0;
 
 	if ((vp->options & VECTOR_RX) > 0)
-		while ((err = vector_mmsg_rx(vp)) > 0)
-			;
+		while (((err = vector_mmsg_rx(vp)) > 0) && (iter < MAX_ITERATIONS))
+			iter++;
 	else
-		while ((err = vector_legacy_rx(vp)) > 0)
-			;
+		while (((err = vector_legacy_rx(vp)) > 0) && (iter < MAX_ITERATIONS))
+			iter++;
 	if ((err != 0) && net_ratelimit())
 		netdev_err(vp->dev, "vector_rx: error(%d)\n", err);
+	if (iter == MAX_ITERATIONS)
+		netdev_err(vp->dev, "vector_rx: device stuck, remote end may have closed the connection\n");
 }
 
 static int vector_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -1021,6 +1042,13 @@ static int vector_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct vector_private *vp = netdev_priv(dev);
 	int queue_depth = 0;
 
+	if (vp->in_error) {
+		deactivate_fd(vp->fds->rx_fd, vp->rx_irq);
+		if ((vp->fds->rx_fd != vp->fds->tx_fd) && (vp->tx_irq != 0))
+			deactivate_fd(vp->fds->tx_fd, vp->tx_irq);
+		return NETDEV_TX_BUSY;
+	}
+
 	if ((vp->options & VECTOR_TX) == 0) {
 		writev_tx(vp, skb);
 		return NETDEV_TX_OK;
@@ -1131,6 +1159,7 @@ static int vector_net_close(struct net_device *dev)
 	vp->fds = NULL;
 	spin_lock_irqsave(&vp->lock, flags);
 	vp->opened = false;
+	vp->in_error = false;
 	spin_unlock_irqrestore(&vp->lock, flags);
 	return 0;
 }
@@ -1498,7 +1527,8 @@ static void vector_eth_configure(
 		.transport_data		= NULL,
 		.in_write_poll		= false,
 		.coalesce		= 2,
-		.req_size		= get_req_size(def)
+		.req_size		= get_req_size(def),
+		.in_error		= false
 		});
 
 	dev->features = dev->hw_features = (NETIF_F_SG | NETIF_F_FRAGLIST);
diff --git a/arch/um/drivers/vector_kern.h b/arch/um/drivers/vector_kern.h
index 0b0a767b9076..4d292e6c07af 100644
--- a/arch/um/drivers/vector_kern.h
+++ b/arch/um/drivers/vector_kern.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2002 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_VECTOR_KERN_H
@@ -116,6 +116,7 @@ struct vector_private {
 	bool rexmit_scheduled;
 	bool opened;
 	bool in_write_poll;
+	bool in_error;
 
 	/* ethtool stats */
 
diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
index 77e4ebc206ae..0794d23f07cb 100644
--- a/arch/um/drivers/vector_transports.c
+++ b/arch/um/drivers/vector_transports.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2017 - Cambridge Greys Limited
  * Copyright (C) 2011 - 2014 Cisco Systems Inc
- * Licensed under the GPL.
  */
 
 #include <linux/etherdevice.h>
@@ -418,7 +418,7 @@ static int build_raw_transport_data(struct vector_private *vp)
 	return 0;
 }
 
-static int build_tap_transport_data(struct vector_private *vp)
+static int build_hybrid_transport_data(struct vector_private *vp)
 {
 	if (uml_raw_enable_vnet_headers(vp->fds->rx_fd)) {
 		vp->form_header = &raw_form_header;
@@ -432,7 +432,7 @@ static int build_tap_transport_data(struct vector_private *vp)
 				NETIF_F_TSO | NETIF_F_GSO | NETIF_F_GRO);
 		netdev_info(
 			vp->dev,
-			"tap/raw: using vnet headers for tso and tx/rx checksum"
+			"tap/raw hybrid: using vnet headers for tso and tx/rx checksum"
 		);
 	} else {
 		return 0; /* do not try to enable tap too if raw failed */
@@ -442,6 +442,38 @@ static int build_tap_transport_data(struct vector_private *vp)
 	return -1;
 }
 
+static int build_tap_transport_data(struct vector_private *vp)
+{
+	/* "Pure" tap uses the same fd for rx and tx */
+	if (uml_tap_enable_vnet_headers(vp->fds->tx_fd)) {
+		vp->form_header = &raw_form_header;
+		vp->verify_header = &raw_verify_header;
+		vp->header_size = sizeof(struct virtio_net_hdr);
+		vp->rx_header_size = sizeof(struct virtio_net_hdr);
+		vp->dev->hw_features |=
+			(NETIF_F_TSO | NETIF_F_GSO | NETIF_F_GRO);
+		vp->dev->features |=
+			(NETIF_F_RXCSUM | NETIF_F_HW_CSUM |
+				NETIF_F_TSO | NETIF_F_GSO | NETIF_F_GRO);
+		netdev_info(
+			vp->dev,
+			"tap: using vnet headers for tso and tx/rx checksum"
+		);
+		return 0;
+	}
+	return -1;
+}
+
+
+static int build_bess_transport_data(struct vector_private *vp)
+{
+	vp->form_header = NULL;
+	vp->verify_header = NULL;
+	vp->header_size = 0;
+	vp->rx_header_size = 0;
+	return 0;
+}
+
 int build_transport_data(struct vector_private *vp)
 {
 	char *transport = uml_vector_fetch_arg(vp->parsed, "transport");
@@ -454,6 +486,10 @@ int build_transport_data(struct vector_private *vp)
 		return build_raw_transport_data(vp);
 	if (strncmp(transport, TRANS_TAP, TRANS_TAP_LEN) == 0)
 		return build_tap_transport_data(vp);
+	if (strncmp(transport, TRANS_HYBRID, TRANS_HYBRID_LEN) == 0)
+		return build_hybrid_transport_data(vp);
+	if (strncmp(transport, TRANS_BESS, TRANS_BESS_LEN) == 0)
+		return build_bess_transport_data(vp);
 	return 0;
 }
 
diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index b3f7b3ca896d..e2c969b9f7ee 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
@@ -17,6 +17,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <sys/socket.h>
+#include <sys/un.h>
 #include <net/ethernet.h>
 #include <netinet/ip.h>
 #include <netinet/ether.h>
@@ -33,7 +34,8 @@
 
 #define ID_GRE 0
 #define ID_L2TPV3 1
-#define ID_MAX 1
+#define ID_BESS 2
+#define ID_MAX 2
 
 #define TOKEN_IFNAME "ifname"
 
@@ -43,8 +45,11 @@
 #define VNET_HDR_FAIL "could not enable vnet headers on fd %d"
 #define TUN_GET_F_FAIL "tapraw: TUNGETFEATURES failed: %s"
 #define L2TPV3_BIND_FAIL "l2tpv3_open : could not bind socket err=%i"
+#define UNIX_BIND_FAIL "unix_open : could not bind socket err=%i"
 #define BPF_ATTACH_FAIL "Failed to attach filter size %d to %d, err %d\n"
 
+#define MAX_UN_LEN 107
+
 /* This is very ugly and brute force lookup, but it is done
  * only once at initialization so not worth doing hashes or
  * anything more intelligent
@@ -114,12 +119,76 @@ cleanup:
 
 #define PATH_NET_TUN "/dev/net/tun"
 
-static struct vector_fds *user_init_tap_fds(struct arglist *ifspec)
+
+static int create_tap_fd(char *iface)
 {
 	struct ifreq ifr;
 	int fd = -1;
-	struct sockaddr_ll sock;
 	int err = -ENOMEM, offload;
+
+	fd = open(PATH_NET_TUN, O_RDWR);
+	if (fd < 0) {
+		printk(UM_KERN_ERR "uml_tap: failed to open tun device\n");
+		goto tap_fd_cleanup;
+	}
+	memset(&ifr, 0, sizeof(ifr));
+	ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
+	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
+
+	err = ioctl(fd, TUNSETIFF, (void *) &ifr);
+	if (err != 0) {
+		printk(UM_KERN_ERR "uml_tap: failed to select tap interface\n");
+		goto tap_fd_cleanup;
+	}
+
+	offload = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6;
+	ioctl(fd, TUNSETOFFLOAD, offload);
+	return fd;
+tap_fd_cleanup:
+	if (fd >= 0)
+		os_close_file(fd);
+	return err;
+}
+
+static int create_raw_fd(char *iface, int flags, int proto)
+{
+	struct ifreq ifr;
+	int fd = -1;
+	struct sockaddr_ll sock;
+	int err = -ENOMEM;
+
+	fd = socket(AF_PACKET, SOCK_RAW, flags);
+	if (fd == -1) {
+		err = -errno;
+		goto raw_fd_cleanup;
+	}
+	memset(&ifr, 0, sizeof(ifr));
+	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
+	if (ioctl(fd, SIOCGIFINDEX, (void *) &ifr) < 0) {
+		err = -errno;
+		goto raw_fd_cleanup;
+	}
+
+	sock.sll_family = AF_PACKET;
+	sock.sll_protocol = htons(proto);
+	sock.sll_ifindex = ifr.ifr_ifindex;
+
+	if (bind(fd,
+		(struct sockaddr *) &sock, sizeof(struct sockaddr_ll)) < 0) {
+		err = -errno;
+		goto raw_fd_cleanup;
+	}
+	return fd;
+raw_fd_cleanup:
+	printk(UM_KERN_ERR "user_init_raw: init failed, error %d", err);
+	if (fd >= 0)
+		os_close_file(fd);
+	return err;
+}
+
+static struct vector_fds *user_init_tap_fds(struct arglist *ifspec)
+{
+	int fd = -1;
 	char *iface;
 	struct vector_fds *result = NULL;
 
@@ -141,117 +210,167 @@ static struct vector_fds *user_init_tap_fds(struct arglist *ifspec)
 
 	/* TAP */
 
-	fd = open(PATH_NET_TUN, O_RDWR);
+	fd = create_tap_fd(iface);
 	if (fd < 0) {
-		printk(UM_KERN_ERR "uml_tap: failed to open tun device\n");
+		printk(UM_KERN_ERR "uml_tap: failed to create tun interface\n");
 		goto tap_cleanup;
 	}
 	result->tx_fd = fd;
-	memset(&ifr, 0, sizeof(ifr));
-	ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
-	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
+	result->rx_fd = fd;
+	return result;
+tap_cleanup:
+	printk(UM_KERN_ERR "user_init_tap: init failed, error %d", fd);
+	if (result != NULL)
+		kfree(result);
+	return NULL;
+}
 
-	err = ioctl(fd, TUNSETIFF, (void *) &ifr);
-	if (err != 0) {
-		printk(UM_KERN_ERR "uml_tap: failed to select tap interface\n");
-		goto tap_cleanup;
+static struct vector_fds *user_init_hybrid_fds(struct arglist *ifspec)
+{
+	char *iface;
+	struct vector_fds *result = NULL;
+
+	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
+	if (iface == NULL) {
+		printk(UM_KERN_ERR "uml_tap: failed to parse interface spec\n");
+		goto hybrid_cleanup;
 	}
 
-	offload = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6;
-	ioctl(fd, TUNSETOFFLOAD, offload);
+	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
+	if (result == NULL) {
+		printk(UM_KERN_ERR "uml_tap: failed to allocate file descriptors\n");
+		goto hybrid_cleanup;
+	}
+	result->rx_fd = -1;
+	result->tx_fd = -1;
+	result->remote_addr = NULL;
+	result->remote_addr_size = 0;
+
+	/* TAP */
+
+	result->tx_fd = create_tap_fd(iface);
+	if (result->tx_fd < 0) {
+		printk(UM_KERN_ERR "uml_tap: failed to create tun interface: %i\n", result->tx_fd);
+		goto hybrid_cleanup;
+	}
 
 	/* RAW */
 
-	fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
-	if (fd == -1) {
+	result->rx_fd = create_raw_fd(iface, ETH_P_ALL, ETH_P_ALL);
+	if (result->rx_fd == -1) {
 		printk(UM_KERN_ERR
-			"uml_tap: failed to create socket: %i\n", -errno);
-		goto tap_cleanup;
+			"uml_tap: failed to create paired raw socket: %i\n", result->rx_fd);
+		goto hybrid_cleanup;
 	}
-	result->rx_fd = fd;
-	memset(&ifr, 0, sizeof(ifr));
-	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
-	if (ioctl(fd, SIOCGIFINDEX, (void *) &ifr) < 0) {
-		printk(UM_KERN_ERR
-			"uml_tap: failed to set interface: %i\n", -errno);
-		goto tap_cleanup;
+	return result;
+hybrid_cleanup:
+	printk(UM_KERN_ERR "user_init_hybrid: init failed");
+	if (result != NULL)
+		kfree(result);
+	return NULL;
+}
+
+static struct vector_fds *user_init_unix_fds(struct arglist *ifspec, int id)
+{
+	int fd = -1;
+	int socktype;
+	char *src, *dst;
+	struct vector_fds *result = NULL;
+	struct sockaddr_un *local_addr = NULL, *remote_addr = NULL;
+
+	src = uml_vector_fetch_arg(ifspec, "src");
+	dst = uml_vector_fetch_arg(ifspec, "dst");
+	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
+	if (result == NULL) {
+		printk(UM_KERN_ERR "unix open:cannot allocate remote addr");
+		goto unix_cleanup;
+	}
+	remote_addr = uml_kmalloc(sizeof(struct sockaddr_un), UM_GFP_KERNEL);
+	if (remote_addr == NULL) {
+		printk(UM_KERN_ERR "unix open:cannot allocate remote addr");
+		goto unix_cleanup;
 	}
 
-	sock.sll_family = AF_PACKET;
-	sock.sll_protocol = htons(ETH_P_ALL);
-	sock.sll_ifindex = ifr.ifr_ifindex;
+	switch (id) {
+	case ID_BESS:
+		socktype = SOCK_SEQPACKET;
+		if ((src != NULL) && (strlen(src) <= MAX_UN_LEN)) {
+			local_addr = uml_kmalloc(sizeof(struct sockaddr_un), UM_GFP_KERNEL);
+			if (local_addr == NULL) {
+				printk(UM_KERN_ERR "bess open:cannot allocate local addr");
+				goto unix_cleanup;
+			}
+			local_addr->sun_family = AF_UNIX;
+			memcpy(local_addr->sun_path, src, strlen(src) + 1);
+		}
+		if ((dst == NULL) || (strlen(dst) > MAX_UN_LEN))
+			goto unix_cleanup;
+		remote_addr->sun_family = AF_UNIX;
+		memcpy(remote_addr->sun_path, dst, strlen(dst) + 1);
+		break;
+	default:
+		printk(KERN_ERR "Unsupported unix socket type\n");
+		return NULL;
+	}
 
-	if (bind(fd,
-		(struct sockaddr *) &sock, sizeof(struct sockaddr_ll)) < 0) {
+	fd = socket(AF_UNIX, socktype, 0);
+	if (fd == -1) {
 		printk(UM_KERN_ERR
-			"user_init_tap: failed to bind raw pair, err %d\n",
-				-errno);
-		goto tap_cleanup;
+			"unix open: could not open socket, error = %d",
+			-errno
+		);
+		goto unix_cleanup;
 	}
+	if (local_addr != NULL) {
+		if (bind(fd, (struct sockaddr *) local_addr, sizeof(struct sockaddr_un))) {
+			printk(UM_KERN_ERR UNIX_BIND_FAIL, errno);
+			goto unix_cleanup;
+		}
+	}
+	switch (id) {
+	case ID_BESS:
+		if (connect(fd, remote_addr, sizeof(struct sockaddr_un)) < 0) {
+			printk(UM_KERN_ERR "bess open:cannot connect to %s %i", remote_addr->sun_path, -errno);
+			goto unix_cleanup;
+		}
+		break;
+	}
+	result->rx_fd = fd;
+	result->tx_fd = fd;
+	result->remote_addr_size = sizeof(struct sockaddr_un);
+	result->remote_addr = remote_addr;
 	return result;
-tap_cleanup:
-	printk(UM_KERN_ERR "user_init_tap: init failed, error %d", err);
-	if (result != NULL) {
-		if (result->rx_fd >= 0)
-			os_close_file(result->rx_fd);
-		if (result->tx_fd >= 0)
-			os_close_file(result->tx_fd);
+unix_cleanup:
+	if (fd >= 0)
+		os_close_file(fd);
+	if (remote_addr != NULL)
+		kfree(remote_addr);
+	if (result != NULL)
 		kfree(result);
-	}
 	return NULL;
 }
 
-
 static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
 {
-	struct ifreq ifr;
 	int rxfd = -1, txfd = -1;
-	struct sockaddr_ll sock;
 	int err = -ENOMEM;
 	char *iface;
 	struct vector_fds *result = NULL;
 
 	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
 	if (iface == NULL)
-		goto cleanup;
+		goto raw_cleanup;
 
-	rxfd = socket(AF_PACKET, SOCK_RAW, ETH_P_ALL);
+	rxfd = create_raw_fd(iface, ETH_P_ALL, ETH_P_ALL);
 	if (rxfd == -1) {
 		err = -errno;
-		goto cleanup;
+		goto raw_cleanup;
 	}
-	txfd = socket(AF_PACKET, SOCK_RAW, 0); /* Turn off RX on this fd */
+	txfd = create_raw_fd(iface, 0, ETH_P_IP); /* Turn off RX on this fd */
 	if (txfd == -1) {
 		err = -errno;
-		goto cleanup;
+		goto raw_cleanup;
 	}
-	memset(&ifr, 0, sizeof(ifr));
-	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
-	if (ioctl(rxfd, SIOCGIFINDEX, (void *) &ifr) < 0) {
-		err = -errno;
-		goto cleanup;
-	}
-
-	sock.sll_family = AF_PACKET;
-	sock.sll_protocol = htons(ETH_P_ALL);
-	sock.sll_ifindex = ifr.ifr_ifindex;
-
-	if (bind(rxfd,
-		(struct sockaddr *) &sock, sizeof(struct sockaddr_ll)) < 0) {
-		err = -errno;
-		goto cleanup;
-	}
-
-	sock.sll_family = AF_PACKET;
-	sock.sll_protocol = htons(ETH_P_IP);
-	sock.sll_ifindex = ifr.ifr_ifindex;
-
-	if (bind(txfd,
-		(struct sockaddr *) &sock, sizeof(struct sockaddr_ll)) < 0) {
-		err = -errno;
-		goto cleanup;
-	}
-
 	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
 	if (result != NULL) {
 		result->rx_fd = rxfd;
@@ -260,13 +379,10 @@ static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
 		result->remote_addr_size = 0;
 	}
 	return result;
-cleanup:
+raw_cleanup:
 	printk(UM_KERN_ERR "user_init_raw: init failed, error %d", err);
-	if (rxfd >= 0)
-		os_close_file(rxfd);
-	if (txfd >= 0)
-		os_close_file(txfd);
-	kfree(result);
+	if (result != NULL)
+		kfree(result);
 	return NULL;
 }
 
@@ -456,12 +572,16 @@ struct vector_fds *uml_vector_user_open(
 	}
 	if (strncmp(transport, TRANS_RAW, TRANS_RAW_LEN) == 0)
 		return user_init_raw_fds(parsed);
+	if (strncmp(transport, TRANS_HYBRID, TRANS_HYBRID_LEN) == 0)
+		return user_init_hybrid_fds(parsed);
 	if (strncmp(transport, TRANS_TAP, TRANS_TAP_LEN) == 0)
 		return user_init_tap_fds(parsed);
 	if (strncmp(transport, TRANS_GRE, TRANS_GRE_LEN) == 0)
 		return user_init_socket_fds(parsed, ID_GRE);
 	if (strncmp(transport, TRANS_L2TPV3, TRANS_L2TPV3_LEN) == 0)
 		return user_init_socket_fds(parsed, ID_L2TPV3);
+	if (strncmp(transport, TRANS_BESS, TRANS_BESS_LEN) == 0)
+		return user_init_unix_fds(parsed, ID_BESS);
 	return NULL;
 }
 
@@ -482,8 +602,9 @@ int uml_vector_sendmsg(int fd, void *hdr, int flags)
 int uml_vector_recvmsg(int fd, void *hdr, int flags)
 {
 	int n;
+	struct msghdr *msg = (struct msghdr *) hdr;
 
-	CATCH_EINTR(n = recvmsg(fd, (struct msghdr *) hdr,  flags));
+	CATCH_EINTR(n = readv(fd, msg->msg_iov, msg->msg_iovlen));
 	if ((n < 0) && (errno == EAGAIN))
 		return 0;
 	if (n >= 0)
@@ -497,7 +618,7 @@ int uml_vector_writev(int fd, void *hdr, int iovcount)
 	int n;
 
 	CATCH_EINTR(n = writev(fd, (struct iovec *) hdr,  iovcount));
-	if ((n < 0) && (errno == EAGAIN))
+	if ((n < 0) && ((errno == EAGAIN) || (errno == ENOBUFS)))
 		return 0;
 	if (n >= 0)
 		return n;
@@ -514,7 +635,7 @@ int uml_vector_sendmmsg(
 	int n;
 
 	CATCH_EINTR(n = sendmmsg(fd, (struct mmsghdr *) msgvec, vlen, flags));
-	if ((n < 0) && (errno == EAGAIN))
+	if ((n < 0) && ((errno == EAGAIN) || (errno == ENOBUFS)))
 		return 0;
 	if (n >= 0)
 		return n;
diff --git a/arch/um/drivers/vector_user.h b/arch/um/drivers/vector_user.h
index d7cbff73b7ff..649ec250268b 100644
--- a/arch/um/drivers/vector_user.h
+++ b/arch/um/drivers/vector_user.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2002 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_VECTOR_USER_H
@@ -16,13 +16,18 @@
 #define TRANS_TAP "tap"
 #define TRANS_TAP_LEN strlen(TRANS_TAP)
 
-
 #define TRANS_GRE "gre"
 #define TRANS_GRE_LEN strlen(TRANS_RAW)
 
 #define TRANS_L2TPV3 "l2tpv3"
 #define TRANS_L2TPV3_LEN strlen(TRANS_L2TPV3)
 
+#define TRANS_HYBRID "hybrid"
+#define TRANS_HYBRID_LEN strlen(TRANS_HYBRID)
+
+#define TRANS_BESS "bess"
+#define TRANS_BESS_LEN strlen(TRANS_BESS)
+
 #ifndef IPPROTO_GRE
 #define IPPROTO_GRE 0x2F
 #endif
diff --git a/arch/um/drivers/vhost_user.h b/arch/um/drivers/vhost_user.h
new file mode 100644
index 000000000000..45ff5ea22fea
--- /dev/null
+++ b/arch/um/drivers/vhost_user.h
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Vhost-user protocol */
+
+#ifndef __VHOST_USER_H__
+#define __VHOST_USER_H__
+
+/* Message flags */
+#define VHOST_USER_FLAG_REPLY		BIT(2)
+#define VHOST_USER_FLAG_NEED_REPLY	BIT(3)
+/* Feature bits */
+#define VHOST_USER_F_PROTOCOL_FEATURES	30
+/* Protocol feature bits */
+#define VHOST_USER_PROTOCOL_F_REPLY_ACK		3
+#define VHOST_USER_PROTOCOL_F_SLAVE_REQ		5
+#define VHOST_USER_PROTOCOL_F_CONFIG		9
+/* Vring state index masks */
+#define VHOST_USER_VRING_INDEX_MASK	0xff
+#define VHOST_USER_VRING_POLL_MASK	BIT(8)
+
+/* Supported version */
+#define VHOST_USER_VERSION		1
+/* Supported transport features */
+#define VHOST_USER_SUPPORTED_F		BIT_ULL(VHOST_USER_F_PROTOCOL_FEATURES)
+/* Supported protocol features */
+#define VHOST_USER_SUPPORTED_PROTOCOL_F	(BIT_ULL(VHOST_USER_PROTOCOL_F_REPLY_ACK) | \
+					 BIT_ULL(VHOST_USER_PROTOCOL_F_SLAVE_REQ) | \
+					 BIT_ULL(VHOST_USER_PROTOCOL_F_CONFIG))
+
+enum vhost_user_request {
+	VHOST_USER_GET_FEATURES = 1,
+	VHOST_USER_SET_FEATURES = 2,
+	VHOST_USER_SET_OWNER = 3,
+	VHOST_USER_RESET_OWNER = 4,
+	VHOST_USER_SET_MEM_TABLE = 5,
+	VHOST_USER_SET_LOG_BASE = 6,
+	VHOST_USER_SET_LOG_FD = 7,
+	VHOST_USER_SET_VRING_NUM = 8,
+	VHOST_USER_SET_VRING_ADDR = 9,
+	VHOST_USER_SET_VRING_BASE = 10,
+	VHOST_USER_GET_VRING_BASE = 11,
+	VHOST_USER_SET_VRING_KICK = 12,
+	VHOST_USER_SET_VRING_CALL = 13,
+	VHOST_USER_SET_VRING_ERR = 14,
+	VHOST_USER_GET_PROTOCOL_FEATURES = 15,
+	VHOST_USER_SET_PROTOCOL_FEATURES = 16,
+	VHOST_USER_GET_QUEUE_NUM = 17,
+	VHOST_USER_SET_VRING_ENABLE = 18,
+	VHOST_USER_SEND_RARP = 19,
+	VHOST_USER_NET_SEND_MTU = 20,
+	VHOST_USER_SET_SLAVE_REQ_FD = 21,
+	VHOST_USER_IOTLB_MSG = 22,
+	VHOST_USER_SET_VRING_ENDIAN = 23,
+	VHOST_USER_GET_CONFIG = 24,
+	VHOST_USER_SET_CONFIG = 25,
+};
+
+enum vhost_user_slave_request {
+	VHOST_USER_SLAVE_IOTLB_MSG = 1,
+	VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
+	VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
+};
+
+struct vhost_user_header {
+	/*
+	 * Use enum vhost_user_request for outgoing messages,
+	 * uses enum vhost_user_slave_request for incoming ones.
+	 */
+	u32 request;
+	u32 flags;
+	u32 size;
+} __packed;
+
+struct vhost_user_config {
+	u32 offset;
+	u32 size;
+	u32 flags;
+	u8 payload[0]; /* Variable length */
+} __packed;
+
+struct vhost_user_vring_state {
+	u32 index;
+	u32 num;
+} __packed;
+
+struct vhost_user_vring_addr {
+	u32 index;
+	u32 flags;
+	u64 desc, used, avail, log;
+} __packed;
+
+struct vhost_user_mem_region {
+	u64 guest_addr;
+	u64 size;
+	u64 user_addr;
+	u64 mmap_offset;
+} __packed;
+
+struct vhost_user_mem_regions {
+	u32 num;
+	u32 padding;
+	struct vhost_user_mem_region regions[2]; /* Currently supporting 2 */
+} __packed;
+
+union vhost_user_payload {
+	u64 integer;
+	struct vhost_user_config config;
+	struct vhost_user_vring_state vring_state;
+	struct vhost_user_vring_addr vring_addr;
+	struct vhost_user_mem_regions mem_regions;
+};
+
+struct vhost_user_msg {
+	struct vhost_user_header header;
+	union vhost_user_payload payload;
+} __packed;
+
+#endif
diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
new file mode 100644
index 000000000000..fc8c52cff5aa
--- /dev/null
+++ b/arch/um/drivers/virtio_uml.c
@@ -0,0 +1,1177 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio vhost-user driver
+ *
+ * Copyright(c) 2019 Intel Corporation
+ *
+ * This module allows virtio devices to be used over a vhost-user socket.
+ *
+ * Guest devices can be instantiated by kernel module or command line
+ * parameters. One device will be created for each parameter. Syntax:
+ *
+ *		[virtio_uml.]device=<socket>:<virtio_id>[:<platform_id>]
+ * where:
+ *		<socket>	:= vhost-user socket path to connect
+ *		<virtio_id>	:= virtio device id (as in virtio_ids.h)
+ *		<platform_id>	:= (optional) platform device id
+ *
+ * example:
+ *		virtio_uml.device=/var/uml.socket:1
+ *
+ * Based on Virtio MMIO driver by Pawel Moll, copyright 2011-2014, ARM Ltd.
+ */
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_ring.h>
+#include <shared/as-layout.h>
+#include <irq_kern.h>
+#include <init.h>
+#include <os.h>
+#include "vhost_user.h"
+
+/* Workaround due to a conflict between irq_user.h and irqreturn.h */
+#ifdef IRQ_NONE
+#undef IRQ_NONE
+#endif
+
+#define MAX_SUPPORTED_QUEUE_SIZE	256
+
+#define to_virtio_uml_device(_vdev) \
+	container_of(_vdev, struct virtio_uml_device, vdev)
+
+struct virtio_uml_device {
+	struct virtio_device vdev;
+	struct platform_device *pdev;
+
+	int sock, req_fd;
+	u64 features;
+	u64 protocol_features;
+	u8 status;
+};
+
+struct virtio_uml_vq_info {
+	int kick_fd, call_fd;
+	char name[32];
+};
+
+extern unsigned long long physmem_size, highmem;
+
+#define vu_err(vu_dev, ...)	dev_err(&(vu_dev)->pdev->dev, __VA_ARGS__)
+
+/* Vhost-user protocol */
+
+static int full_sendmsg_fds(int fd, const void *buf, unsigned int len,
+			    const int *fds, unsigned int fds_num)
+{
+	int rc;
+
+	do {
+		rc = os_sendmsg_fds(fd, buf, len, fds, fds_num);
+		if (rc > 0) {
+			buf += rc;
+			len -= rc;
+			fds = NULL;
+			fds_num = 0;
+		}
+	} while (len && (rc >= 0 || rc == -EINTR));
+
+	if (rc < 0)
+		return rc;
+	return 0;
+}
+
+static int full_read(int fd, void *buf, int len)
+{
+	int rc;
+
+	do {
+		rc = os_read_file(fd, buf, len);
+		if (rc > 0) {
+			buf += rc;
+			len -= rc;
+		}
+	} while (len && (rc > 0 || rc == -EINTR));
+
+	if (rc < 0)
+		return rc;
+	if (rc == 0)
+		return -ECONNRESET;
+	return 0;
+}
+
+static int vhost_user_recv_header(int fd, struct vhost_user_msg *msg)
+{
+	return full_read(fd, msg, sizeof(msg->header));
+}
+
+static int vhost_user_recv(int fd, struct vhost_user_msg *msg,
+			   size_t max_payload_size)
+{
+	size_t size;
+	int rc = vhost_user_recv_header(fd, msg);
+
+	if (rc)
+		return rc;
+	size = msg->header.size;
+	if (size > max_payload_size)
+		return -EPROTO;
+	return full_read(fd, &msg->payload, size);
+}
+
+static int vhost_user_recv_resp(struct virtio_uml_device *vu_dev,
+				struct vhost_user_msg *msg,
+				size_t max_payload_size)
+{
+	int rc = vhost_user_recv(vu_dev->sock, msg, max_payload_size);
+
+	if (rc)
+		return rc;
+
+	if (msg->header.flags != (VHOST_USER_FLAG_REPLY | VHOST_USER_VERSION))
+		return -EPROTO;
+
+	return 0;
+}
+
+static int vhost_user_recv_u64(struct virtio_uml_device *vu_dev,
+			       u64 *value)
+{
+	struct vhost_user_msg msg;
+	int rc = vhost_user_recv_resp(vu_dev, &msg,
+				      sizeof(msg.payload.integer));
+
+	if (rc)
+		return rc;
+	if (msg.header.size != sizeof(msg.payload.integer))
+		return -EPROTO;
+	*value = msg.payload.integer;
+	return 0;
+}
+
+static int vhost_user_recv_req(struct virtio_uml_device *vu_dev,
+			       struct vhost_user_msg *msg,
+			       size_t max_payload_size)
+{
+	int rc = vhost_user_recv(vu_dev->req_fd, msg, max_payload_size);
+
+	if (rc)
+		return rc;
+
+	if ((msg->header.flags & ~VHOST_USER_FLAG_NEED_REPLY) !=
+			VHOST_USER_VERSION)
+		return -EPROTO;
+
+	return 0;
+}
+
+static int vhost_user_send(struct virtio_uml_device *vu_dev,
+			   bool need_response, struct vhost_user_msg *msg,
+			   int *fds, size_t num_fds)
+{
+	size_t size = sizeof(msg->header) + msg->header.size;
+	bool request_ack;
+	int rc;
+
+	msg->header.flags |= VHOST_USER_VERSION;
+
+	/*
+	 * The need_response flag indicates that we already need a response,
+	 * e.g. to read the features. In these cases, don't request an ACK as
+	 * it is meaningless. Also request an ACK only if supported.
+	 */
+	request_ack = !need_response;
+	if (!(vu_dev->protocol_features &
+			BIT_ULL(VHOST_USER_PROTOCOL_F_REPLY_ACK)))
+		request_ack = false;
+
+	if (request_ack)
+		msg->header.flags |= VHOST_USER_FLAG_NEED_REPLY;
+
+	rc = full_sendmsg_fds(vu_dev->sock, msg, size, fds, num_fds);
+	if (rc < 0)
+		return rc;
+
+	if (request_ack) {
+		uint64_t status;
+
+		rc = vhost_user_recv_u64(vu_dev, &status);
+		if (rc)
+			return rc;
+
+		if (status) {
+			vu_err(vu_dev, "slave reports error: %llu\n", status);
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+static int vhost_user_send_no_payload(struct virtio_uml_device *vu_dev,
+				      bool need_response, u32 request)
+{
+	struct vhost_user_msg msg = {
+		.header.request = request,
+	};
+
+	return vhost_user_send(vu_dev, need_response, &msg, NULL, 0);
+}
+
+static int vhost_user_send_no_payload_fd(struct virtio_uml_device *vu_dev,
+					 u32 request, int fd)
+{
+	struct vhost_user_msg msg = {
+		.header.request = request,
+	};
+
+	return vhost_user_send(vu_dev, false, &msg, &fd, 1);
+}
+
+static int vhost_user_send_u64(struct virtio_uml_device *vu_dev,
+			       u32 request, u64 value)
+{
+	struct vhost_user_msg msg = {
+		.header.request = request,
+		.header.size = sizeof(msg.payload.integer),
+		.payload.integer = value,
+	};
+
+	return vhost_user_send(vu_dev, false, &msg, NULL, 0);
+}
+
+static int vhost_user_set_owner(struct virtio_uml_device *vu_dev)
+{
+	return vhost_user_send_no_payload(vu_dev, false, VHOST_USER_SET_OWNER);
+}
+
+static int vhost_user_get_features(struct virtio_uml_device *vu_dev,
+				   u64 *features)
+{
+	int rc = vhost_user_send_no_payload(vu_dev, true,
+					    VHOST_USER_GET_FEATURES);
+
+	if (rc)
+		return rc;
+	return vhost_user_recv_u64(vu_dev, features);
+}
+
+static int vhost_user_set_features(struct virtio_uml_device *vu_dev,
+				   u64 features)
+{
+	return vhost_user_send_u64(vu_dev, VHOST_USER_SET_FEATURES, features);
+}
+
+static int vhost_user_get_protocol_features(struct virtio_uml_device *vu_dev,
+					    u64 *protocol_features)
+{
+	int rc = vhost_user_send_no_payload(vu_dev, true,
+			VHOST_USER_GET_PROTOCOL_FEATURES);
+
+	if (rc)
+		return rc;
+	return vhost_user_recv_u64(vu_dev, protocol_features);
+}
+
+static int vhost_user_set_protocol_features(struct virtio_uml_device *vu_dev,
+					    u64 protocol_features)
+{
+	return vhost_user_send_u64(vu_dev, VHOST_USER_SET_PROTOCOL_FEATURES,
+				   protocol_features);
+}
+
+static void vhost_user_reply(struct virtio_uml_device *vu_dev,
+			     struct vhost_user_msg *msg, int response)
+{
+	struct vhost_user_msg reply = {
+		.payload.integer = response,
+	};
+	size_t size = sizeof(reply.header) + sizeof(reply.payload.integer);
+	int rc;
+
+	reply.header = msg->header;
+	reply.header.flags &= ~VHOST_USER_FLAG_NEED_REPLY;
+	reply.header.flags |= VHOST_USER_FLAG_REPLY;
+	reply.header.size = sizeof(reply.payload.integer);
+
+	rc = full_sendmsg_fds(vu_dev->req_fd, &reply, size, NULL, 0);
+
+	if (rc)
+		vu_err(vu_dev,
+		       "sending reply to slave request failed: %d (size %zu)\n",
+		       rc, size);
+}
+
+static irqreturn_t vu_req_interrupt(int irq, void *data)
+{
+	struct virtio_uml_device *vu_dev = data;
+	int response = 1;
+	struct {
+		struct vhost_user_msg msg;
+		u8 extra_payload[512];
+	} msg;
+	int rc;
+
+	rc = vhost_user_recv_req(vu_dev, &msg.msg,
+				 sizeof(msg.msg.payload) +
+				 sizeof(msg.extra_payload));
+
+	if (rc)
+		return IRQ_NONE;
+
+	switch (msg.msg.header.request) {
+	case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG:
+		virtio_config_changed(&vu_dev->vdev);
+		response = 0;
+		break;
+	case VHOST_USER_SLAVE_IOTLB_MSG:
+		/* not supported - VIRTIO_F_IOMMU_PLATFORM */
+	case VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG:
+		/* not supported - VHOST_USER_PROTOCOL_F_HOST_NOTIFIER */
+	default:
+		vu_err(vu_dev, "unexpected slave request %d\n",
+		       msg.msg.header.request);
+	}
+
+	if (msg.msg.header.flags & VHOST_USER_FLAG_NEED_REPLY)
+		vhost_user_reply(vu_dev, &msg.msg, response);
+
+	return IRQ_HANDLED;
+}
+
+static int vhost_user_init_slave_req(struct virtio_uml_device *vu_dev)
+{
+	int rc, req_fds[2];
+
+	/* Use a pipe for slave req fd, SIGIO is not supported for eventfd */
+	rc = os_pipe(req_fds, true, true);
+	if (rc < 0)
+		return rc;
+	vu_dev->req_fd = req_fds[0];
+
+	rc = um_request_irq(VIRTIO_IRQ, vu_dev->req_fd, IRQ_READ,
+			    vu_req_interrupt, IRQF_SHARED,
+			    vu_dev->pdev->name, vu_dev);
+	if (rc)
+		goto err_close;
+
+	rc = vhost_user_send_no_payload_fd(vu_dev, VHOST_USER_SET_SLAVE_REQ_FD,
+					   req_fds[1]);
+	if (rc)
+		goto err_free_irq;
+
+	goto out;
+
+err_free_irq:
+	um_free_irq(VIRTIO_IRQ, vu_dev);
+err_close:
+	os_close_file(req_fds[0]);
+out:
+	/* Close unused write end of request fds */
+	os_close_file(req_fds[1]);
+	return rc;
+}
+
+static int vhost_user_init(struct virtio_uml_device *vu_dev)
+{
+	int rc = vhost_user_set_owner(vu_dev);
+
+	if (rc)
+		return rc;
+	rc = vhost_user_get_features(vu_dev, &vu_dev->features);
+	if (rc)
+		return rc;
+
+	if (vu_dev->features & BIT_ULL(VHOST_USER_F_PROTOCOL_FEATURES)) {
+		rc = vhost_user_get_protocol_features(vu_dev,
+				&vu_dev->protocol_features);
+		if (rc)
+			return rc;
+		vu_dev->protocol_features &= VHOST_USER_SUPPORTED_PROTOCOL_F;
+		rc = vhost_user_set_protocol_features(vu_dev,
+				vu_dev->protocol_features);
+		if (rc)
+			return rc;
+	}
+
+	if (vu_dev->protocol_features &
+			BIT_ULL(VHOST_USER_PROTOCOL_F_SLAVE_REQ)) {
+		rc = vhost_user_init_slave_req(vu_dev);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}
+
+static void vhost_user_get_config(struct virtio_uml_device *vu_dev,
+				  u32 offset, void *buf, u32 len)
+{
+	u32 cfg_size = offset + len;
+	struct vhost_user_msg *msg;
+	size_t payload_size = sizeof(msg->payload.config) + cfg_size;
+	size_t msg_size = sizeof(msg->header) + payload_size;
+	int rc;
+
+	if (!(vu_dev->protocol_features &
+	      BIT_ULL(VHOST_USER_PROTOCOL_F_CONFIG)))
+		return;
+
+	msg = kzalloc(msg_size, GFP_KERNEL);
+	if (!msg)
+		return;
+	msg->header.request = VHOST_USER_GET_CONFIG;
+	msg->header.size = payload_size;
+	msg->payload.config.offset = 0;
+	msg->payload.config.size = cfg_size;
+
+	rc = vhost_user_send(vu_dev, true, msg, NULL, 0);
+	if (rc) {
+		vu_err(vu_dev, "sending VHOST_USER_GET_CONFIG failed: %d\n",
+		       rc);
+		goto free;
+	}
+
+	rc = vhost_user_recv_resp(vu_dev, msg, msg_size);
+	if (rc) {
+		vu_err(vu_dev,
+		       "receiving VHOST_USER_GET_CONFIG response failed: %d\n",
+		       rc);
+		goto free;
+	}
+
+	if (msg->header.size != payload_size ||
+	    msg->payload.config.size != cfg_size) {
+		rc = -EPROTO;
+		vu_err(vu_dev,
+		       "Invalid VHOST_USER_GET_CONFIG sizes (payload %d expected %zu, config %u expected %u)\n",
+		       msg->header.size, payload_size,
+		       msg->payload.config.size, cfg_size);
+		goto free;
+	}
+	memcpy(buf, msg->payload.config.payload + offset, len);
+
+free:
+	kfree(msg);
+}
+
+static void vhost_user_set_config(struct virtio_uml_device *vu_dev,
+				  u32 offset, const void *buf, u32 len)
+{
+	struct vhost_user_msg *msg;
+	size_t payload_size = sizeof(msg->payload.config) + len;
+	size_t msg_size = sizeof(msg->header) + payload_size;
+	int rc;
+
+	if (!(vu_dev->protocol_features &
+	      BIT_ULL(VHOST_USER_PROTOCOL_F_CONFIG)))
+		return;
+
+	msg = kzalloc(msg_size, GFP_KERNEL);
+	if (!msg)
+		return;
+	msg->header.request = VHOST_USER_SET_CONFIG;
+	msg->header.size = payload_size;
+	msg->payload.config.offset = offset;
+	msg->payload.config.size = len;
+	memcpy(msg->payload.config.payload, buf, len);
+
+	rc = vhost_user_send(vu_dev, false, msg, NULL, 0);
+	if (rc)
+		vu_err(vu_dev, "sending VHOST_USER_SET_CONFIG failed: %d\n",
+		       rc);
+
+	kfree(msg);
+}
+
+static int vhost_user_init_mem_region(u64 addr, u64 size, int *fd_out,
+				      struct vhost_user_mem_region *region_out)
+{
+	unsigned long long mem_offset;
+	int rc = phys_mapping(addr, &mem_offset);
+
+	if (WARN(rc < 0, "phys_mapping of 0x%llx returned %d\n", addr, rc))
+		return -EFAULT;
+	*fd_out = rc;
+	region_out->guest_addr = addr;
+	region_out->user_addr = addr;
+	region_out->size = size;
+	region_out->mmap_offset = mem_offset;
+
+	/* Ensure mapping is valid for the entire region */
+	rc = phys_mapping(addr + size - 1, &mem_offset);
+	if (WARN(rc != *fd_out, "phys_mapping of 0x%llx failed: %d != %d\n",
+		 addr + size - 1, rc, *fd_out))
+		return -EFAULT;
+	return 0;
+}
+
+static int vhost_user_set_mem_table(struct virtio_uml_device *vu_dev)
+{
+	struct vhost_user_msg msg = {
+		.header.request = VHOST_USER_SET_MEM_TABLE,
+		.header.size = sizeof(msg.payload.mem_regions),
+		.payload.mem_regions.num = 1,
+	};
+	unsigned long reserved = uml_reserved - uml_physmem;
+	int fds[2];
+	int rc;
+
+	/*
+	 * This is a bit tricky, see also the comment with setup_physmem().
+	 *
+	 * Essentially, setup_physmem() uses a file to mmap() our physmem,
+	 * but the code and data we *already* have is omitted. To us, this
+	 * is no difference, since they both become part of our address
+	 * space and memory consumption. To somebody looking in from the
+	 * outside, however, it is different because the part of our memory
+	 * consumption that's already part of the binary (code/data) is not
+	 * mapped from the file, so it's not visible to another mmap from
+	 * the file descriptor.
+	 *
+	 * Thus, don't advertise this space to the vhost-user slave. This
+	 * means that the slave will likely abort or similar when we give
+	 * it an address from the hidden range, since it's not marked as
+	 * a valid address, but at least that way we detect the issue and
+	 * don't just have the slave read an all-zeroes buffer from the
+	 * shared memory file, or write something there that we can never
+	 * see (depending on the direction of the virtqueue traffic.)
+	 *
+	 * Since we usually don't want to use .text for virtio buffers,
+	 * this effectively means that you cannot use
+	 *  1) global variables, which are in the .bss and not in the shm
+	 *     file-backed memory
+	 *  2) the stack in some processes, depending on where they have
+	 *     their stack (or maybe only no interrupt stack?)
+	 *
+	 * The stack is already not typically valid for DMA, so this isn't
+	 * much of a restriction, but global variables might be encountered.
+	 *
+	 * It might be possible to fix it by copying around the data that's
+	 * between bss_start and where we map the file now, but it's not
+	 * something that you typically encounter with virtio drivers, so
+	 * it didn't seem worthwhile.
+	 */
+	rc = vhost_user_init_mem_region(reserved, physmem_size - reserved,
+					&fds[0],
+					&msg.payload.mem_regions.regions[0]);
+
+	if (rc < 0)
+		return rc;
+	if (highmem) {
+		msg.payload.mem_regions.num++;
+		rc = vhost_user_init_mem_region(__pa(end_iomem), highmem,
+				&fds[1], &msg.payload.mem_regions.regions[1]);
+		if (rc < 0)
+			return rc;
+	}
+
+	return vhost_user_send(vu_dev, false, &msg, fds,
+			       msg.payload.mem_regions.num);
+}
+
+static int vhost_user_set_vring_state(struct virtio_uml_device *vu_dev,
+				      u32 request, u32 index, u32 num)
+{
+	struct vhost_user_msg msg = {
+		.header.request = request,
+		.header.size = sizeof(msg.payload.vring_state),
+		.payload.vring_state.index = index,
+		.payload.vring_state.num = num,
+	};
+
+	return vhost_user_send(vu_dev, false, &msg, NULL, 0);
+}
+
+static int vhost_user_set_vring_num(struct virtio_uml_device *vu_dev,
+				    u32 index, u32 num)
+{
+	return vhost_user_set_vring_state(vu_dev, VHOST_USER_SET_VRING_NUM,
+					  index, num);
+}
+
+static int vhost_user_set_vring_base(struct virtio_uml_device *vu_dev,
+				     u32 index, u32 offset)
+{
+	return vhost_user_set_vring_state(vu_dev, VHOST_USER_SET_VRING_BASE,
+					  index, offset);
+}
+
+static int vhost_user_set_vring_addr(struct virtio_uml_device *vu_dev,
+				     u32 index, u64 desc, u64 used, u64 avail,
+				     u64 log)
+{
+	struct vhost_user_msg msg = {
+		.header.request = VHOST_USER_SET_VRING_ADDR,
+		.header.size = sizeof(msg.payload.vring_addr),
+		.payload.vring_addr.index = index,
+		.payload.vring_addr.desc = desc,
+		.payload.vring_addr.used = used,
+		.payload.vring_addr.avail = avail,
+		.payload.vring_addr.log = log,
+	};
+
+	return vhost_user_send(vu_dev, false, &msg, NULL, 0);
+}
+
+static int vhost_user_set_vring_fd(struct virtio_uml_device *vu_dev,
+				   u32 request, int index, int fd)
+{
+	struct vhost_user_msg msg = {
+		.header.request = request,
+		.header.size = sizeof(msg.payload.integer),
+		.payload.integer = index,
+	};
+
+	if (index & ~VHOST_USER_VRING_INDEX_MASK)
+		return -EINVAL;
+	if (fd < 0) {
+		msg.payload.integer |= VHOST_USER_VRING_POLL_MASK;
+		return vhost_user_send(vu_dev, false, &msg, NULL, 0);
+	}
+	return vhost_user_send(vu_dev, false, &msg, &fd, 1);
+}
+
+static int vhost_user_set_vring_call(struct virtio_uml_device *vu_dev,
+				     int index, int fd)
+{
+	return vhost_user_set_vring_fd(vu_dev, VHOST_USER_SET_VRING_CALL,
+				       index, fd);
+}
+
+static int vhost_user_set_vring_kick(struct virtio_uml_device *vu_dev,
+				     int index, int fd)
+{
+	return vhost_user_set_vring_fd(vu_dev, VHOST_USER_SET_VRING_KICK,
+				       index, fd);
+}
+
+static int vhost_user_set_vring_enable(struct virtio_uml_device *vu_dev,
+				       u32 index, bool enable)
+{
+	if (!(vu_dev->features & BIT_ULL(VHOST_USER_F_PROTOCOL_FEATURES)))
+		return 0;
+
+	return vhost_user_set_vring_state(vu_dev, VHOST_USER_SET_VRING_ENABLE,
+					  index, enable);
+}
+
+
+/* Virtio interface */
+
+static bool vu_notify(struct virtqueue *vq)
+{
+	struct virtio_uml_vq_info *info = vq->priv;
+	const uint64_t n = 1;
+	int rc;
+
+	do {
+		rc = os_write_file(info->kick_fd, &n, sizeof(n));
+	} while (rc == -EINTR);
+	return !WARN(rc != sizeof(n), "write returned %d\n", rc);
+}
+
+static irqreturn_t vu_interrupt(int irq, void *opaque)
+{
+	struct virtqueue *vq = opaque;
+	struct virtio_uml_vq_info *info = vq->priv;
+	uint64_t n;
+	int rc;
+	irqreturn_t ret = IRQ_NONE;
+
+	do {
+		rc = os_read_file(info->call_fd, &n, sizeof(n));
+		if (rc == sizeof(n))
+			ret |= vring_interrupt(irq, vq);
+	} while (rc == sizeof(n) || rc == -EINTR);
+	WARN(rc != -EAGAIN, "read returned %d\n", rc);
+	return ret;
+}
+
+
+static void vu_get(struct virtio_device *vdev, unsigned offset,
+		   void *buf, unsigned len)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+	vhost_user_get_config(vu_dev, offset, buf, len);
+}
+
+static void vu_set(struct virtio_device *vdev, unsigned offset,
+		   const void *buf, unsigned len)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+	vhost_user_set_config(vu_dev, offset, buf, len);
+}
+
+static u8 vu_get_status(struct virtio_device *vdev)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+	return vu_dev->status;
+}
+
+static void vu_set_status(struct virtio_device *vdev, u8 status)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+	vu_dev->status = status;
+}
+
+static void vu_reset(struct virtio_device *vdev)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+	vu_dev->status = 0;
+}
+
+static void vu_del_vq(struct virtqueue *vq)
+{
+	struct virtio_uml_vq_info *info = vq->priv;
+
+	um_free_irq(VIRTIO_IRQ, vq);
+
+	os_close_file(info->call_fd);
+	os_close_file(info->kick_fd);
+
+	vring_del_virtqueue(vq);
+	kfree(info);
+}
+
+static void vu_del_vqs(struct virtio_device *vdev)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+	struct virtqueue *vq, *n;
+	u64 features;
+
+	/* Note: reverse order as a workaround to a decoding bug in snabb */
+	list_for_each_entry_reverse(vq, &vdev->vqs, list)
+		WARN_ON(vhost_user_set_vring_enable(vu_dev, vq->index, false));
+
+	/* Ensure previous messages have been processed */
+	WARN_ON(vhost_user_get_features(vu_dev, &features));
+
+	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+		vu_del_vq(vq);
+}
+
+static int vu_setup_vq_call_fd(struct virtio_uml_device *vu_dev,
+			       struct virtqueue *vq)
+{
+	struct virtio_uml_vq_info *info = vq->priv;
+	int call_fds[2];
+	int rc;
+
+	/* Use a pipe for call fd, since SIGIO is not supported for eventfd */
+	rc = os_pipe(call_fds, true, true);
+	if (rc < 0)
+		return rc;
+
+	info->call_fd = call_fds[0];
+	rc = um_request_irq(VIRTIO_IRQ, info->call_fd, IRQ_READ,
+			    vu_interrupt, IRQF_SHARED, info->name, vq);
+	if (rc)
+		goto close_both;
+
+	rc = vhost_user_set_vring_call(vu_dev, vq->index, call_fds[1]);
+	if (rc)
+		goto release_irq;
+
+	goto out;
+
+release_irq:
+	um_free_irq(VIRTIO_IRQ, vq);
+close_both:
+	os_close_file(call_fds[0]);
+out:
+	/* Close (unused) write end of call fds */
+	os_close_file(call_fds[1]);
+
+	return rc;
+}
+
+static struct virtqueue *vu_setup_vq(struct virtio_device *vdev,
+				     unsigned index, vq_callback_t *callback,
+				     const char *name, bool ctx)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+	struct platform_device *pdev = vu_dev->pdev;
+	struct virtio_uml_vq_info *info;
+	struct virtqueue *vq;
+	int num = MAX_SUPPORTED_QUEUE_SIZE;
+	int rc;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info) {
+		rc = -ENOMEM;
+		goto error_kzalloc;
+	}
+	snprintf(info->name, sizeof(info->name), "%s.%d-%s", pdev->name,
+		 pdev->id, name);
+
+	vq = vring_create_virtqueue(index, num, PAGE_SIZE, vdev, true, true,
+				    ctx, vu_notify, callback, info->name);
+	if (!vq) {
+		rc = -ENOMEM;
+		goto error_create;
+	}
+	vq->priv = info;
+	num = virtqueue_get_vring_size(vq);
+
+	rc = os_eventfd(0, 0);
+	if (rc < 0)
+		goto error_kick;
+	info->kick_fd = rc;
+
+	rc = vu_setup_vq_call_fd(vu_dev, vq);
+	if (rc)
+		goto error_call;
+
+	rc = vhost_user_set_vring_num(vu_dev, index, num);
+	if (rc)
+		goto error_setup;
+
+	rc = vhost_user_set_vring_base(vu_dev, index, 0);
+	if (rc)
+		goto error_setup;
+
+	rc = vhost_user_set_vring_addr(vu_dev, index,
+				       virtqueue_get_desc_addr(vq),
+				       virtqueue_get_used_addr(vq),
+				       virtqueue_get_avail_addr(vq),
+				       (u64) -1);
+	if (rc)
+		goto error_setup;
+
+	return vq;
+
+error_setup:
+	um_free_irq(VIRTIO_IRQ, vq);
+	os_close_file(info->call_fd);
+error_call:
+	os_close_file(info->kick_fd);
+error_kick:
+	vring_del_virtqueue(vq);
+error_create:
+	kfree(info);
+error_kzalloc:
+	return ERR_PTR(rc);
+}
+
+static int vu_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+		       struct virtqueue *vqs[], vq_callback_t *callbacks[],
+		       const char * const names[], const bool *ctx,
+		       struct irq_affinity *desc)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+	int i, queue_idx = 0, rc;
+	struct virtqueue *vq;
+
+	rc = vhost_user_set_mem_table(vu_dev);
+	if (rc)
+		return rc;
+
+	for (i = 0; i < nvqs; ++i) {
+		if (!names[i]) {
+			vqs[i] = NULL;
+			continue;
+		}
+
+		vqs[i] = vu_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
+				     ctx ? ctx[i] : false);
+		if (IS_ERR(vqs[i])) {
+			rc = PTR_ERR(vqs[i]);
+			goto error_setup;
+		}
+	}
+
+	list_for_each_entry(vq, &vdev->vqs, list) {
+		struct virtio_uml_vq_info *info = vq->priv;
+
+		rc = vhost_user_set_vring_kick(vu_dev, vq->index,
+					       info->kick_fd);
+		if (rc)
+			goto error_setup;
+
+		rc = vhost_user_set_vring_enable(vu_dev, vq->index, true);
+		if (rc)
+			goto error_setup;
+	}
+
+	return 0;
+
+error_setup:
+	vu_del_vqs(vdev);
+	return rc;
+}
+
+static u64 vu_get_features(struct virtio_device *vdev)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+	return vu_dev->features;
+}
+
+static int vu_finalize_features(struct virtio_device *vdev)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+	u64 supported = vdev->features & VHOST_USER_SUPPORTED_F;
+
+	vring_transport_features(vdev);
+	vu_dev->features = vdev->features | supported;
+
+	return vhost_user_set_features(vu_dev, vu_dev->features);
+}
+
+static const char *vu_bus_name(struct virtio_device *vdev)
+{
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+	return vu_dev->pdev->name;
+}
+
+static const struct virtio_config_ops virtio_uml_config_ops = {
+	.get = vu_get,
+	.set = vu_set,
+	.get_status = vu_get_status,
+	.set_status = vu_set_status,
+	.reset = vu_reset,
+	.find_vqs = vu_find_vqs,
+	.del_vqs = vu_del_vqs,
+	.get_features = vu_get_features,
+	.finalize_features = vu_finalize_features,
+	.bus_name = vu_bus_name,
+};
+
+static void virtio_uml_release_dev(struct device *d)
+{
+	struct virtio_device *vdev =
+			container_of(d, struct virtio_device, dev);
+	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+	/* might not have been opened due to not negotiating the feature */
+	if (vu_dev->req_fd >= 0) {
+		um_free_irq(VIRTIO_IRQ, vu_dev);
+		os_close_file(vu_dev->req_fd);
+	}
+
+	os_close_file(vu_dev->sock);
+}
+
+/* Platform device */
+
+struct virtio_uml_platform_data {
+	u32 virtio_device_id;
+	const char *socket_path;
+};
+
+static int virtio_uml_probe(struct platform_device *pdev)
+{
+	struct virtio_uml_platform_data *pdata = pdev->dev.platform_data;
+	struct virtio_uml_device *vu_dev;
+	int rc;
+
+	if (!pdata)
+		return -EINVAL;
+
+	vu_dev = devm_kzalloc(&pdev->dev, sizeof(*vu_dev), GFP_KERNEL);
+	if (!vu_dev)
+		return -ENOMEM;
+
+	vu_dev->vdev.dev.parent = &pdev->dev;
+	vu_dev->vdev.dev.release = virtio_uml_release_dev;
+	vu_dev->vdev.config = &virtio_uml_config_ops;
+	vu_dev->vdev.id.device = pdata->virtio_device_id;
+	vu_dev->vdev.id.vendor = VIRTIO_DEV_ANY_ID;
+	vu_dev->pdev = pdev;
+	vu_dev->req_fd = -1;
+
+	do {
+		rc = os_connect_socket(pdata->socket_path);
+	} while (rc == -EINTR);
+	if (rc < 0)
+		return rc;
+	vu_dev->sock = rc;
+
+	rc = vhost_user_init(vu_dev);
+	if (rc)
+		goto error_init;
+
+	platform_set_drvdata(pdev, vu_dev);
+
+	rc = register_virtio_device(&vu_dev->vdev);
+	if (rc)
+		put_device(&vu_dev->vdev.dev);
+	return rc;
+
+error_init:
+	os_close_file(vu_dev->sock);
+	return rc;
+}
+
+static int virtio_uml_remove(struct platform_device *pdev)
+{
+	struct virtio_uml_device *vu_dev = platform_get_drvdata(pdev);
+
+	unregister_virtio_device(&vu_dev->vdev);
+	return 0;
+}
+
+/* Command line device list */
+
+static void vu_cmdline_release_dev(struct device *d)
+{
+}
+
+static struct device vu_cmdline_parent = {
+	.init_name = "virtio-uml-cmdline",
+	.release = vu_cmdline_release_dev,
+};
+
+static bool vu_cmdline_parent_registered;
+static int vu_cmdline_id;
+
+static int vu_cmdline_set(const char *device, const struct kernel_param *kp)
+{
+	const char *ids = strchr(device, ':');
+	unsigned int virtio_device_id;
+	int processed, consumed, err;
+	char *socket_path;
+	struct virtio_uml_platform_data pdata;
+	struct platform_device *pdev;
+
+	if (!ids || ids == device)
+		return -EINVAL;
+
+	processed = sscanf(ids, ":%u%n:%d%n",
+			   &virtio_device_id, &consumed,
+			   &vu_cmdline_id, &consumed);
+
+	if (processed < 1 || ids[consumed])
+		return -EINVAL;
+
+	if (!vu_cmdline_parent_registered) {
+		err = device_register(&vu_cmdline_parent);
+		if (err) {
+			pr_err("Failed to register parent device!\n");
+			put_device(&vu_cmdline_parent);
+			return err;
+		}
+		vu_cmdline_parent_registered = true;
+	}
+
+	socket_path = kmemdup_nul(device, ids - device, GFP_KERNEL);
+	if (!socket_path)
+		return -ENOMEM;
+
+	pdata.virtio_device_id = (u32) virtio_device_id;
+	pdata.socket_path = socket_path;
+
+	pr_info("Registering device virtio-uml.%d id=%d at %s\n",
+		vu_cmdline_id, virtio_device_id, socket_path);
+
+	pdev = platform_device_register_data(&vu_cmdline_parent, "virtio-uml",
+					     vu_cmdline_id++, &pdata,
+					     sizeof(pdata));
+	err = PTR_ERR_OR_ZERO(pdev);
+	if (err)
+		goto free;
+	return 0;
+
+free:
+	kfree(socket_path);
+	return err;
+}
+
+static int vu_cmdline_get_device(struct device *dev, void *data)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct virtio_uml_platform_data *pdata = pdev->dev.platform_data;
+	char *buffer = data;
+	unsigned int len = strlen(buffer);
+
+	snprintf(buffer + len, PAGE_SIZE - len, "%s:%d:%d\n",
+		 pdata->socket_path, pdata->virtio_device_id, pdev->id);
+	return 0;
+}
+
+static int vu_cmdline_get(char *buffer, const struct kernel_param *kp)
+{
+	buffer[0] = '\0';
+	if (vu_cmdline_parent_registered)
+		device_for_each_child(&vu_cmdline_parent, buffer,
+				      vu_cmdline_get_device);
+	return strlen(buffer) + 1;
+}
+
+static const struct kernel_param_ops vu_cmdline_param_ops = {
+	.set = vu_cmdline_set,
+	.get = vu_cmdline_get,
+};
+
+device_param_cb(device, &vu_cmdline_param_ops, NULL, S_IRUSR);
+__uml_help(vu_cmdline_param_ops,
+"virtio_uml.device=<socket>:<virtio_id>[:<platform_id>]\n"
+"    Configure a virtio device over a vhost-user socket.\n"
+"    See virtio_ids.h for a list of possible virtio device id values.\n"
+"    Optionally use a specific platform_device id.\n\n"
+);
+
+
+static int vu_unregister_cmdline_device(struct device *dev, void *data)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct virtio_uml_platform_data *pdata = pdev->dev.platform_data;
+
+	kfree(pdata->socket_path);
+	platform_device_unregister(pdev);
+	return 0;
+}
+
+static void vu_unregister_cmdline_devices(void)
+{
+	if (vu_cmdline_parent_registered) {
+		device_for_each_child(&vu_cmdline_parent, NULL,
+				      vu_unregister_cmdline_device);
+		device_unregister(&vu_cmdline_parent);
+		vu_cmdline_parent_registered = false;
+	}
+}
+
+/* Platform driver */
+
+static const struct of_device_id virtio_uml_match[] = {
+	{ .compatible = "virtio,uml", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, virtio_uml_match);
+
+static struct platform_driver virtio_uml_driver = {
+	.probe = virtio_uml_probe,
+	.remove = virtio_uml_remove,
+	.driver = {
+		.name = "virtio-uml",
+		.of_match_table = virtio_uml_match,
+	},
+};
+
+static int __init virtio_uml_init(void)
+{
+	return platform_driver_register(&virtio_uml_driver);
+}
+
+static void __exit virtio_uml_exit(void)
+{
+	platform_driver_unregister(&virtio_uml_driver);
+	vu_unregister_cmdline_devices();
+}
+
+module_init(virtio_uml_init);
+module_exit(virtio_uml_exit);
+__uml_exitcall(virtio_uml_exit);
+
+MODULE_DESCRIPTION("UML driver for vhost-user virtio devices");
+MODULE_LICENSE("GPL");
diff --git a/arch/um/drivers/xterm.c b/arch/um/drivers/xterm.c
index 20e30be44795..fc7f1e746703 100644
--- a/arch/um/drivers/xterm.c
+++ b/arch/um/drivers/xterm.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stddef.h>
diff --git a/arch/um/drivers/xterm.h b/arch/um/drivers/xterm.h
index 56b9c4aba423..5968da3a6aba 100644
--- a/arch/um/drivers/xterm.h
+++ b/arch/um/drivers/xterm.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __XTERM_H__
diff --git a/arch/um/drivers/xterm_kern.c b/arch/um/drivers/xterm_kern.c
index e8f9957bfbf6..d64ef6d0d463 100644
--- a/arch/um/drivers/xterm_kern.c
+++ b/arch/um/drivers/xterm_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /* 
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/slab.h>
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index b352ed09260e..398006d27e40 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-generic-y += barrier.h
 generic-y += bpf_perf_event.h
 generic-y += bug.h
 generic-y += compat.h
diff --git a/arch/um/include/asm/common.lds.S b/arch/um/include/asm/common.lds.S
index 4049f2c46387..d7086b985f27 100644
--- a/arch/um/include/asm/common.lds.S
+++ b/arch/um/include/asm/common.lds.S
@@ -83,8 +83,8 @@
 	__preinit_array_end = .;
   }
   .init_array : {
+        /* dummy - we call this ourselves */
 	__init_array_start = .;
-	*(.init_array)
 	__init_array_end = .;
   }
   .fini_array : {
diff --git a/arch/um/include/asm/irq.h b/arch/um/include/asm/irq.h
index 49ed3e35b35a..42c6205e2dc4 100644
--- a/arch/um/include/asm/irq.h
+++ b/arch/um/include/asm/irq.h
@@ -17,17 +17,18 @@
 #define TELNETD_IRQ 		12
 #define XTERM_IRQ 		13
 #define RANDOM_IRQ 		14
+#define VIRTIO_IRQ		15
 
 #ifdef CONFIG_UML_NET_VECTOR
 
-#define VECTOR_BASE_IRQ		15
+#define VECTOR_BASE_IRQ		(VIRTIO_IRQ + 1)
 #define VECTOR_IRQ_SPACE	8
 
-#define LAST_IRQ (VECTOR_IRQ_SPACE + VECTOR_BASE_IRQ)
+#define LAST_IRQ (VECTOR_IRQ_SPACE + VECTOR_BASE_IRQ - 1)
 
 #else
 
-#define LAST_IRQ RANDOM_IRQ
+#define LAST_IRQ VIRTIO_IRQ
 
 #endif
 
diff --git a/arch/um/include/asm/irqflags.h b/arch/um/include/asm/irqflags.h
index cbc6c0013a64..0642ad9035d1 100644
--- a/arch/um/include/asm/irqflags.h
+++ b/arch/um/include/asm/irqflags.h
@@ -32,7 +32,6 @@ static inline void arch_local_irq_disable(void)
 }
 
 #define ARCH_IRQ_DISABLED	0
-#define ARCh_IRQ_ENABLED	(SIGIO|SIGVTALRM)
 
 #include <asm-generic/irqflags.h>
 
diff --git a/arch/um/include/asm/kmap_types.h b/arch/um/include/asm/kmap_types.h
index 2e0a6b1d8300..b0bd12de1d23 100644
--- a/arch/um/include/asm/kmap_types.h
+++ b/arch/um/include/asm/kmap_types.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_KMAP_TYPES_H
diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index da705448590f..5b072aba5b65 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __ARCH_UM_MMU_H
diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
index 00cefd33afdd..5aee0626e390 100644
--- a/arch/um/include/asm/mmu_context.h
+++ b/arch/um/include/asm/mmu_context.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_MMU_CONTEXT_H
diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h
index f878bec23576..95af12e82a32 100644
--- a/arch/um/include/asm/page.h
+++ b/arch/um/include/asm/page.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2000 - 2003 Jeff Dike (jdike@addtoit.com)
  * Copyright 2003 PathScale, Inc.
- * Licensed under the GPL
  */
 
 #ifndef __UM_PAGE_H
diff --git a/arch/um/include/asm/pgalloc.h b/arch/um/include/asm/pgalloc.h
index d7b282e9c4d5..023599c3fa51 100644
--- a/arch/um/include/asm/pgalloc.h
+++ b/arch/um/include/asm/pgalloc.h
@@ -1,8 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
  * Copyright 2003 PathScale, Inc.
  * Derived from include/asm-i386/pgalloc.h and include/asm-i386/pgtable.h
- * Licensed under the GPL
  */
 
 #ifndef __UM_PGALLOC_H
diff --git a/arch/um/include/asm/pgtable-2level.h b/arch/um/include/asm/pgtable-2level.h
index 179c0ea87a0c..32b3d26a7109 100644
--- a/arch/um/include/asm/pgtable-2level.h
+++ b/arch/um/include/asm/pgtable-2level.h
@@ -1,8 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
  * Copyright 2003 PathScale, Inc.
  * Derived from include/asm-i386/pgtable.h
- * Licensed under the GPL
  */
 
 #ifndef __UM_PGTABLE_2LEVEL_H
diff --git a/arch/um/include/asm/pgtable-3level.h b/arch/um/include/asm/pgtable-3level.h
index c4d876dfb9ac..9812269fefc9 100644
--- a/arch/um/include/asm/pgtable-3level.h
+++ b/arch/um/include/asm/pgtable-3level.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright 2003 PathScale Inc
  * Derived from include/asm-i386/pgtable.h
- * Licensed under the GPL
  */
 
 #ifndef __UM_PGTABLE_3LEVEL_H
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index b377df76cc28..e4d3ed980d82 100644
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -1,8 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright 2003 PathScale, Inc.
  * Derived from include/asm-i386/pgtable.h
- * Licensed under the GPL
  */
 
 #ifndef __UM_PGTABLE_H
diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h
index b58b746d3f2c..afd9b267cf81 100644
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_PROCESSOR_GENERIC_H
diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h
index 5ab20620fc97..81c647ef9c6c 100644
--- a/arch/um/include/asm/ptrace-generic.h
+++ b/arch/um/include/asm/ptrace-generic.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_PTRACE_GENERIC_H
diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index 4eecd960ee8c..4c19ce4c49f1 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_THREAD_INFO_H
diff --git a/arch/um/include/asm/tlbflush.h b/arch/um/include/asm/tlbflush.h
index 614f2c091178..a5bda890390d 100644
--- a/arch/um/include/asm/tlbflush.h
+++ b/arch/um/include/asm/tlbflush.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_TLBFLUSH_H
diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h
index cc00fc50768f..fe66d659acad 100644
--- a/arch/um/include/asm/uaccess.h
+++ b/arch/um/include/asm/uaccess.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
  * Copyright (C) 2015 Richard Weinberger (richard@nod.at)
- * Licensed under the GPL
  */
 
 #ifndef __UM_UACCESS_H
diff --git a/arch/um/include/shared/arch.h b/arch/um/include/shared/arch.h
index 4f46abda060d..880ee42a3329 100644
--- a/arch/um/include/shared/arch.h
+++ b/arch/um/include/shared/arch.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __ARCH_H__
diff --git a/arch/um/include/shared/as-layout.h b/arch/um/include/shared/as-layout.h
index ca1843e1df15..5f286ef2721b 100644
--- a/arch/um/include/shared/as-layout.h
+++ b/arch/um/include/shared/as-layout.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __START_H__
diff --git a/arch/um/include/shared/elf_user.h b/arch/um/include/shared/elf_user.h
index 53516b637272..fd461ee40c05 100644
--- a/arch/um/include/shared/elf_user.h
+++ b/arch/um/include/shared/elf_user.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2004 Fujitsu Siemens Computers GmbH
  * Author: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
- * Licensed under the GPL
  */
 
 #ifndef __ELF_USER_H__
diff --git a/arch/um/include/shared/frame_kern.h b/arch/um/include/shared/frame_kern.h
index a5cde5c433b4..ed952ac661ca 100644
--- a/arch/um/include/shared/frame_kern.h
+++ b/arch/um/include/shared/frame_kern.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __FRAME_KERN_H_
diff --git a/arch/um/include/shared/irq_kern.h b/arch/um/include/shared/irq_kern.h
index e05bd667de15..7cd1a10c6244 100644
--- a/arch/um/include/shared/irq_kern.h
+++ b/arch/um/include/shared/irq_kern.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __IRQ_KERN_H__
diff --git a/arch/um/include/shared/irq_user.h b/arch/um/include/shared/irq_user.h
index e7242a0ae489..107751dce153 100644
--- a/arch/um/include/shared/irq_user.h
+++ b/arch/um/include/shared/irq_user.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __IRQ_USER_H__
diff --git a/arch/um/include/shared/kern.h b/arch/um/include/shared/kern.h
index 6cd01240bbf0..3a9c75a8413c 100644
--- a/arch/um/include/shared/kern.h
+++ b/arch/um/include/shared/kern.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __KERN_H__
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h
index 35ab97e4bb9b..ccafb62e8cce 100644
--- a/arch/um/include/shared/kern_util.h
+++ b/arch/um/include/shared/kern_util.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __KERN_UTIL_H__
diff --git a/arch/um/include/shared/longjmp.h b/arch/um/include/shared/longjmp.h
index b3315c1f198b..85a1cc290ecb 100644
--- a/arch/um/include/shared/longjmp.h
+++ b/arch/um/include/shared/longjmp.h
@@ -18,7 +18,7 @@ extern void longjmp(jmp_buf, int);
 	enable = get_signals(); \
 	n = setjmp(*buf); \
 	if(n != 0) \
-		set_signals(enable); \
+		set_signals_trace(enable); \
 	n; })
 
 #endif
diff --git a/arch/um/include/shared/mem.h b/arch/um/include/shared/mem.h
index 5cd40e99e8d5..4862c91d4213 100644
--- a/arch/um/include/shared/mem.h
+++ b/arch/um/include/shared/mem.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __MEM_H__
diff --git a/arch/um/include/shared/net_kern.h b/arch/um/include/shared/net_kern.h
index 40442b98b173..a87be13c5b87 100644
--- a/arch/um/include/shared/net_kern.h
+++ b/arch/um/include/shared/net_kern.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2002 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_NET_KERN_H
diff --git a/arch/um/include/shared/net_user.h b/arch/um/include/shared/net_user.h
index 3dabbe128e40..1b0531769a5e 100644
--- a/arch/um/include/shared/net_user.h
+++ b/arch/um/include/shared/net_user.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_NET_USER_H__
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 4a62ac4251a5..506bcd1bca68 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -1,8 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __OS_H__
@@ -36,6 +36,8 @@
 #define OS_LIB_PATH	"/usr/lib/"
 #endif
 
+#define OS_SENDMSG_MAX_FDS 8
+
 /*
  * types taken from stat_file() in hostfs_user.c
  * (if they are wrong here, they are wrong there...).
@@ -176,6 +178,9 @@ extern unsigned os_major(unsigned long long dev);
 extern unsigned os_minor(unsigned long long dev);
 extern unsigned long long os_makedev(unsigned major, unsigned minor);
 extern int os_falloc_punch(int fd, unsigned long long offset, int count);
+extern int os_eventfd(unsigned int initval, int flags);
+extern int os_sendmsg_fds(int fd, const void *buf, unsigned int len,
+			  const int *fds, unsigned int fds_num);
 
 /* start_up.c */
 extern void os_early_checks(void);
@@ -232,6 +237,7 @@ extern void block_signals(void);
 extern void unblock_signals(void);
 extern int get_signals(void);
 extern int set_signals(int enable);
+extern int set_signals_trace(int enable);
 extern int os_is_signal_stack(void);
 extern void deliver_alarm(void);
 
@@ -317,4 +323,10 @@ extern unsigned long os_get_top_address(void);
 
 long syscall(long number, ...);
 
+/* irqflags tracing */
+extern void block_signals_trace(void);
+extern void unblock_signals_trace(void);
+extern void um_trace_signals_on(void);
+extern void um_trace_signals_off(void);
+
 #endif
diff --git a/arch/um/include/shared/ptrace_user.h b/arch/um/include/shared/ptrace_user.h
index 56b2f284b108..95455e8996e7 100644
--- a/arch/um/include/shared/ptrace_user.h
+++ b/arch/um/include/shared/ptrace_user.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __PTRACE_USER_H__
diff --git a/arch/um/include/shared/registers.h b/arch/um/include/shared/registers.h
index a74449b5b0e3..0c50fa6e8a55 100644
--- a/arch/um/include/shared/registers.h
+++ b/arch/um/include/shared/registers.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2004 PathScale, Inc
- * Licensed under the GPL
  */
 
 #ifndef __REGISTERS_H
diff --git a/arch/um/include/shared/sigio.h b/arch/um/include/shared/sigio.h
index 434f1a9ae4b3..8fe8f57c05de 100644
--- a/arch/um/include/shared/sigio.h
+++ b/arch/um/include/shared/sigio.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __SIGIO_H__
diff --git a/arch/um/include/shared/skas/mm_id.h b/arch/um/include/shared/skas/mm_id.h
index 48dd0989ddaa..4337b4ced095 100644
--- a/arch/um/include/shared/skas/mm_id.h
+++ b/arch/um/include/shared/skas/mm_id.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2005 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __MM_ID_H
diff --git a/arch/um/include/shared/skas/skas.h b/arch/um/include/shared/skas/skas.h
index 911f3c45ad1f..c93d2cbc8f32 100644
--- a/arch/um/include/shared/skas/skas.h
+++ b/arch/um/include/shared/skas/skas.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __SKAS_H
diff --git a/arch/um/include/shared/skas/stub-data.h b/arch/um/include/shared/skas/stub-data.h
index 13f404e1262b..6b01d97a9386 100644
--- a/arch/um/include/shared/skas/stub-data.h
+++ b/arch/um/include/shared/skas/stub-data.h
@@ -1,8 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
 
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2005 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #ifndef __STUB_DATA_H
diff --git a/arch/um/include/shared/timer-internal.h b/arch/um/include/shared/timer-internal.h
index 9991ec2371e4..2d2d13c9b46f 100644
--- a/arch/um/include/shared/timer-internal.h
+++ b/arch/um/include/shared/timer-internal.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2012 - 2014 Cisco Systems
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __TIMER_INTERNAL_H__
@@ -43,6 +43,11 @@ static inline void time_travel_set_timer_expiry(unsigned long long expiry)
 {
 	time_travel_timer_expiry = expiry;
 }
+
+static inline void time_travel_set_timer_interval(unsigned long long interval)
+{
+	time_travel_timer_interval = interval;
+}
 #else
 #define time_travel_mode TT_MODE_OFF
 #define time_travel_time 0
@@ -61,6 +66,10 @@ static inline void time_travel_set_timer_expiry(unsigned long long expiry)
 {
 }
 
+static inline void time_travel_set_timer_interval(unsigned long long interval)
+{
+}
+
 #define time_travel_timer_mode TT_TMR_DISABLED
 #endif
 
diff --git a/arch/um/include/shared/um_malloc.h b/arch/um/include/shared/um_malloc.h
index 6395fef6b69b..13da93284c2c 100644
--- a/arch/um/include/shared/um_malloc.h
+++ b/arch/um/include/shared/um_malloc.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
- * Licensed under the GPL
  */
 
 #ifndef __UM_MALLOC_H__
diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
index 4cff19f6207a..e793e4212f0a 100644
--- a/arch/um/include/shared/user.h
+++ b/arch/um/include/shared/user.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __USER_H__
diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index 2f36d515762e..5aa882011e04 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -1,6 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux,intel}.com)
-# Licensed under the GPL
 #
 
 # Don't instrument UML-specific code; without this, we may crash when
@@ -13,7 +13,6 @@ CPPFLAGS_vmlinux.lds := -DSTART=$(LDS_START)		\
                         -DELF_FORMAT=$(LDS_ELF_FORMAT)	\
 			$(LDS_EXTRA)
 extra-y := vmlinux.lds
-clean-files :=
 
 obj-y = config.o exec.o exitcode.o irq.o ksyms.o mem.o \
 	physmem.o process.o ptrace.o reboot.o sigio.o \
diff --git a/arch/um/kernel/config.c.in b/arch/um/kernel/config.c.in
index 972bf1659564..3ece3c3b31cc 100644
--- a/arch/um/kernel/config.c.in
+++ b/arch/um/kernel/config.c.in
@@ -1,6 +1,6 @@
-/* 
+// SPDX-License-Identifier: GPL-2.0
+/*
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S
index 5568cf882371..c69d69ee96be 100644
--- a/arch/um/kernel/dyn.lds.S
+++ b/arch/um/kernel/dyn.lds.S
@@ -70,6 +70,8 @@ SECTIONS
     SCHED_TEXT
     CPUIDLE_TEXT
     LOCK_TEXT
+    IRQENTRY_TEXT
+    SOFTIRQENTRY_TEXT
     *(.fixup)
     *(.stub .text.* .gnu.linkonce.t.*)
     /* .gnu.warning sections are handled specially by elf32.em.  */
@@ -101,7 +103,6 @@ SECTIONS
      be empty, which isn't pretty.  */
   . = ALIGN(32 / 8);
   .preinit_array     : { *(.preinit_array) }
-  .init_array     : { *(.init_array) }
   .fini_array     : { *(.fini_array) }
   .data           : {
     INIT_TASK_DATA(KERNEL_STACK_SIZE)
diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index 783b9247161f..e8fd5d540b05 100644
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/stddef.h>
diff --git a/arch/um/kernel/exitcode.c b/arch/um/kernel/exitcode.c
index 546302e3b7fb..369fd844e195 100644
--- a/arch/um/kernel/exitcode.c
+++ b/arch/um/kernel/exitcode.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/ctype.h>
diff --git a/arch/um/kernel/gmon_syms.c b/arch/um/kernel/gmon_syms.c
index f138a4a0db99..9361a8eb9bf1 100644
--- a/arch/um/kernel/gmon_syms.c
+++ b/arch/um/kernel/gmon_syms.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/module.h>
diff --git a/arch/um/kernel/gprof_syms.c b/arch/um/kernel/gprof_syms.c
index 74ddb44288a3..84d536908775 100644
--- a/arch/um/kernel/gprof_syms.c
+++ b/arch/um/kernel/gprof_syms.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /* 
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/module.h>
diff --git a/arch/um/kernel/initrd.c b/arch/um/kernel/initrd.c
index 1dcd310cb34d..c1981ffb7179 100644
--- a/arch/um/kernel/initrd.c
+++ b/arch/um/kernel/initrd.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/init.h>
diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
index efde1f16c603..3577118bb4a5 100644
--- a/arch/um/kernel/irq.c
+++ b/arch/um/kernel/irq.c
@@ -1,8 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2017 - Cambridge Greys Ltd
  * Copyright (C) 2011 - 2014 Cisco Systems Inc
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  * Derived (i.e. mostly copied) from arch/i386/kernel/irq.c:
  *	Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
  */
@@ -480,7 +480,7 @@ void __init init_IRQ(void)
 	irq_set_chip_and_handler(TIMER_IRQ, &SIGVTALRM_irq_type, handle_edge_irq);
 
 
-	for (i = 1; i < LAST_IRQ; i++)
+	for (i = 1; i <= LAST_IRQ; i++)
 		irq_set_chip_and_handler(i, &normal_irq_type, handle_edge_irq);
 	/* Initialize EPOLL Loop */
 	os_setup_epoll();
diff --git a/arch/um/kernel/ksyms.c b/arch/um/kernel/ksyms.c
index 232b22307fdd..8ade54a86a7e 100644
--- a/arch/um/kernel/ksyms.c
+++ b/arch/um/kernel/ksyms.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /* 
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/module.h>
@@ -38,6 +38,8 @@ EXPORT_SYMBOL(run_helper);
 EXPORT_SYMBOL(os_major);
 EXPORT_SYMBOL(os_minor);
 EXPORT_SYMBOL(os_makedev);
+EXPORT_SYMBOL(os_eventfd);
+EXPORT_SYMBOL(os_sendmsg_fds);
 
 EXPORT_SYMBOL(add_sigio_fd);
 EXPORT_SYMBOL(ignore_sigio_fd);
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index de58e976b9bc..417ff647fb37 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/stddef.h>
@@ -31,6 +31,7 @@ pgd_t swapper_pg_dir[PTRS_PER_PGD];
 
 /* Initialized at boot time, and readonly after that */
 unsigned long long highmem;
+EXPORT_SYMBOL(highmem);
 int kmalloc_ok = 0;
 
 /* Used during early boot */
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index 5bf56af4d5b9..e7c7b53a1435 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/module.h>
@@ -143,6 +143,7 @@ int phys_mapping(unsigned long phys, unsigned long long *offset_out)
 
 	return fd;
 }
+EXPORT_SYMBOL(phys_mapping);
 
 static int __init uml_mem_setup(char *line, int *add)
 {
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 6bede7888fc2..263a8f069133 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -1,9 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright 2003 PathScale, Inc.
- * Licensed under the GPL
  */
 
 #include <linux/stddef.h>
@@ -210,15 +210,23 @@ static void time_travel_sleep(unsigned long long duration)
 	if (time_travel_mode != TT_MODE_INFCPU)
 		os_timer_disable();
 
-	if (time_travel_timer_mode != TT_TMR_DISABLED ||
+	while (time_travel_timer_mode == TT_TMR_PERIODIC &&
+	       time_travel_timer_expiry < time_travel_time)
+		time_travel_set_timer_expiry(time_travel_timer_expiry +
+					     time_travel_timer_interval);
+
+	if (time_travel_timer_mode != TT_TMR_DISABLED &&
 	    time_travel_timer_expiry < next) {
 		if (time_travel_timer_mode == TT_TMR_ONESHOT)
 			time_travel_set_timer_mode(TT_TMR_DISABLED);
 		/*
-		 * time_travel_time will be adjusted in the timer
-		 * IRQ handler so it works even when the signal
-		 * comes from the OS timer
+		 * In basic mode, time_travel_time will be adjusted in
+		 * the timer IRQ handler so it works even when the signal
+		 * comes from the OS timer, see there.
 		 */
+		if (time_travel_mode != TT_MODE_BASIC)
+			time_travel_set_time(time_travel_timer_expiry);
+
 		deliver_alarm();
 	} else {
 		time_travel_set_time(next);
diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index da1e96b1ec3e..b425f47bddbb 100644
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/audit.h>
diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c
index 71f3e9217cf2..48c0610d506e 100644
--- a/arch/um/kernel/reboot.c
+++ b/arch/um/kernel/reboot.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /* 
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/sched/signal.h>
diff --git a/arch/um/kernel/sigio.c b/arch/um/kernel/sigio.c
index 3fb6a4041ed6..10c99e058fca 100644
--- a/arch/um/kernel/sigio.c
+++ b/arch/um/kernel/sigio.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
- * Licensed under the GPL
  */
 
 #include <linux/interrupt.h>
diff --git a/arch/um/kernel/signal.c b/arch/um/kernel/signal.c
index 57acbd67d85d..3d57c71c532e 100644
--- a/arch/um/kernel/signal.c
+++ b/arch/um/kernel/signal.c
@@ -1,20 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/module.h>
 #include <linux/ptrace.h>
 #include <linux/sched.h>
+#include <linux/ftrace.h>
 #include <asm/siginfo.h>
 #include <asm/signal.h>
 #include <asm/unistd.h>
 #include <frame_kern.h>
 #include <kern_util.h>
+#include <os.h>
 
 EXPORT_SYMBOL(block_signals);
 EXPORT_SYMBOL(unblock_signals);
 
+void block_signals_trace(void)
+{
+	block_signals();
+	if (current_thread_info())
+		trace_hardirqs_off();
+}
+
+void unblock_signals_trace(void)
+{
+	if (current_thread_info())
+		trace_hardirqs_on();
+	unblock_signals();
+}
+
+void um_trace_signals_on(void)
+{
+	if (current_thread_info())
+		trace_hardirqs_on();
+}
+
+void um_trace_signals_off(void)
+{
+	if (current_thread_info())
+		trace_hardirqs_off();
+}
+
 /*
  * OK, we're invoking a handler
  */
diff --git a/arch/um/kernel/skas/Makefile b/arch/um/kernel/skas/Makefile
index 5bd3edfcfedf..f3d494a4fd9b 100644
--- a/arch/um/kernel/skas/Makefile
+++ b/arch/um/kernel/skas/Makefile
@@ -1,6 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
-# Licensed under the GPL
 #
 
 obj-y := clone.o mmu.o process.o syscall.o uaccess.o
diff --git a/arch/um/kernel/skas/clone.c b/arch/um/kernel/skas/clone.c
index 0f25d41b1031..bfb70c456b30 100644
--- a/arch/um/kernel/skas/clone.c
+++ b/arch/um/kernel/skas/clone.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <signal.h>
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 29e7f5f9f188..b5e3d91fc9c2 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/mm.h>
@@ -63,12 +63,12 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
 	if (current->mm != NULL && current->mm != &init_mm)
 		from_mm = &current->mm->context;
 
-	block_signals();
+	block_signals_trace();
 	if (from_mm)
 		to_mm->id.u.pid = copy_context_skas0(stack,
 						     from_mm->id.u.pid);
 	else to_mm->id.u.pid = start_userspace(stack);
-	unblock_signals();
+	unblock_signals_trace();
 
 	if (to_mm->id.u.pid < 0) {
 		ret = to_mm->id.u.pid;
diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
index d4dbf08722d6..f2ac134c9752 100644
--- a/arch/um/kernel/skas/process.c
+++ b/arch/um/kernel/skas/process.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/init.h>
@@ -19,7 +19,7 @@ static int __init start_kernel_proc(void *unused)
 {
 	int pid;
 
-	block_signals();
+	block_signals_trace();
 	pid = os_getpid();
 
 	cpu_tasks[0].pid = pid;
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index 44bb10785075..f574b1856bc6 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/kernel.h>
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index bd3cb694322c..3236052f20e6 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/err.h>
diff --git a/arch/um/kernel/syscall.c b/arch/um/kernel/syscall.c
index 35f7047bdebc..eed54c53fbbb 100644
--- a/arch/um/kernel/syscall.c
+++ b/arch/um/kernel/syscall.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/file.h>
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index 234757233355..94ea87bd231c 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -1,9 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2012-2014 Cisco Systems
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/clockchips.h>
@@ -39,7 +39,15 @@ void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 {
 	unsigned long flags;
 
-	if (time_travel_mode != TT_MODE_OFF)
+	/*
+	 * In basic time-travel mode we still get real interrupts
+	 * (signals) but since we don't read time from the OS, we
+	 * must update the simulated time here to the expiry when
+	 * we get a signal.
+	 * This is not the case in inf-cpu mode, since there we
+	 * never get any real signals from the OS.
+	 */
+	if (time_travel_mode == TT_MODE_BASIC)
 		time_travel_set_time(time_travel_timer_expiry);
 
 	local_irq_save(flags);
@@ -65,6 +73,7 @@ static int itimer_set_periodic(struct clock_event_device *evt)
 	if (time_travel_mode != TT_MODE_OFF) {
 		time_travel_set_timer_mode(TT_TMR_PERIODIC);
 		time_travel_set_timer_expiry(time_travel_time + interval);
+		time_travel_set_timer_interval(interval);
 	}
 
 	if (time_travel_mode != TT_MODE_INFCPU)
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 45f739bf302f..b7eaf655635c 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/mm.h>
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 58fe36856182..e62296c66c95 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/mm.h>
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index a818ccef30ca..0f40eccbd759 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/delay.h>
@@ -113,6 +113,7 @@ static int have_root __initdata = 0;
 
 /* Set in uml_mem_setup and modified in linux_main */
 long long physmem_size = 32 * 1024 * 1024;
+EXPORT_SYMBOL(physmem_size);
 
 static const char *usage_string =
 "User Mode Linux v%s\n"
diff --git a/arch/um/kernel/umid.c b/arch/um/kernel/umid.c
index 10bf4aca529f..8031a038eb58 100644
--- a/arch/um/kernel/umid.c
+++ b/arch/um/kernel/umid.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <asm/errno.h>
diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S
index 36b07ec09742..9f21443be2c9 100644
--- a/arch/um/kernel/uml.lds.S
+++ b/arch/um/kernel/uml.lds.S
@@ -31,6 +31,8 @@ SECTIONS
     SCHED_TEXT
     CPUIDLE_TEXT
     LOCK_TEXT
+    IRQENTRY_TEXT
+    SOFTIRQENTRY_TEXT
     *(.fixup)
     /* .gnu.warning sections are handled specially by elf32.em.  */
     *(.gnu.warning)
diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index 455b500afe97..839915b8c31c 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -1,6 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
 # 
 # Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
-# Licensed under the GPL
 #
 
 # Don't instrument UML-specific code
diff --git a/arch/um/os-Linux/drivers/Makefile b/arch/um/os-Linux/drivers/Makefile
index 6c546dc9222b..d79e75f1b69a 100644
--- a/arch/um/os-Linux/drivers/Makefile
+++ b/arch/um/os-Linux/drivers/Makefile
@@ -1,6 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
 # 
 # Copyright (C) 2000, 2002 Jeff Dike (jdike@karaya.com)
-# Licensed under the GPL
 #
 
 ethertap-objs := ethertap_kern.o ethertap_user.o
diff --git a/arch/um/os-Linux/drivers/etap.h b/arch/um/os-Linux/drivers/etap.h
index 54183a679fdd..a475259f90e1 100644
--- a/arch/um/os-Linux/drivers/etap.h
+++ b/arch/um/os-Linux/drivers/etap.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __DRIVERS_ETAP_H
diff --git a/arch/um/os-Linux/drivers/ethertap_kern.c b/arch/um/os-Linux/drivers/ethertap_kern.c
index f424600a583f..3182e759d8de 100644
--- a/arch/um/os-Linux/drivers/ethertap_kern.c
+++ b/arch/um/os-Linux/drivers/ethertap_kern.c
@@ -1,9 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright (C) 2001 by various other people who didn't put their name here.
- * Licensed under the GPL.
  */
 
 #include <linux/init.h>
diff --git a/arch/um/os-Linux/drivers/ethertap_user.c b/arch/um/os-Linux/drivers/ethertap_user.c
index 6d4918246ffe..9483021d86dd 100644
--- a/arch/um/os-Linux/drivers/ethertap_user.c
+++ b/arch/um/os-Linux/drivers/ethertap_user.c
@@ -1,9 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
  * James Leu (jleu@mindspring.net).
  * Copyright (C) 2001 by various other people who didn't put their name here.
- * Licensed under the GPL.
  */
 
 #include <stdio.h>
diff --git a/arch/um/os-Linux/drivers/tuntap.h b/arch/um/os-Linux/drivers/tuntap.h
index 7367354ac8df..e364e42abfc5 100644
--- a/arch/um/os-Linux/drivers/tuntap.h
+++ b/arch/um/os-Linux/drivers/tuntap.h
@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /* 
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #ifndef __UM_TUNTAP_H
diff --git a/arch/um/os-Linux/drivers/tuntap_kern.c b/arch/um/os-Linux/drivers/tuntap_kern.c
index d9d56e5810fe..adcb6717be6f 100644
--- a/arch/um/os-Linux/drivers/tuntap_kern.c
+++ b/arch/um/os-Linux/drivers/tuntap_kern.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <linux/netdevice.h>
diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c
index db24ce0d09a6..53eb3d508645 100644
--- a/arch/um/os-Linux/drivers/tuntap_user.c
+++ b/arch/um/os-Linux/drivers/tuntap_user.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /* 
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index f25b110d4e70..5133e3afb96f 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
@@ -15,6 +15,7 @@
 #include <sys/sysmacros.h>
 #include <sys/un.h>
 #include <sys/types.h>
+#include <sys/eventfd.h>
 #include <os.h>
 
 static void copy_stat(struct uml_stat *dst, const struct stat64 *src)
@@ -620,3 +621,46 @@ int os_falloc_punch(int fd, unsigned long long offset, int len)
 	return n;
 }
 
+int os_eventfd(unsigned int initval, int flags)
+{
+	int fd = eventfd(initval, flags);
+
+	if (fd < 0)
+		return -errno;
+	return fd;
+}
+
+int os_sendmsg_fds(int fd, const void *buf, unsigned int len, const int *fds,
+		   unsigned int fds_num)
+{
+	struct iovec iov = {
+		.iov_base = (void *) buf,
+		.iov_len = len,
+	};
+	union {
+		char control[CMSG_SPACE(sizeof(*fds) * OS_SENDMSG_MAX_FDS)];
+		struct cmsghdr align;
+	} u;
+	unsigned int fds_size = sizeof(*fds) * fds_num;
+	struct msghdr msg = {
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+		.msg_control = u.control,
+		.msg_controllen = CMSG_SPACE(fds_size),
+	};
+	struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+	int err;
+
+	if (fds_num > OS_SENDMSG_MAX_FDS)
+		return -EINVAL;
+	memset(u.control, 0, sizeof(u.control));
+	cmsg->cmsg_level = SOL_SOCKET;
+	cmsg->cmsg_type = SCM_RIGHTS;
+	cmsg->cmsg_len = CMSG_LEN(fds_size);
+	memcpy(CMSG_DATA(cmsg), fds, fds_size);
+	err = sendmsg(fd, &msg, 0);
+
+	if (err < 0)
+		return -errno;
+	return err;
+}
diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
index 3f02d4232812..9fa6e4187d4f 100644
--- a/arch/um/os-Linux/helper.c
+++ b/arch/um/os-Linux/helper.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdlib.h>
diff --git a/arch/um/os-Linux/irq.c b/arch/um/os-Linux/irq.c
index 365823010346..d508310ee5e1 100644
--- a/arch/um/os-Linux/irq.c
+++ b/arch/um/os-Linux/irq.c
@@ -1,8 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2017 - Cambridge Greys Ltd
  * Copyright (C) 2011 - 2014 Cisco Systems Inc
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdlib.h>
diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
index f1fee2b91239..8014dfac644d 100644
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
@@ -170,7 +170,7 @@ int __init main(int argc, char **argv, char **envp)
 	 * that they won't be delivered after the exec, when
 	 * they are definitely not expected.
 	 */
-	unblock_signals();
+	unblock_signals_trace();
 
 	os_info("\n");
 	/* Reboot */
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index e162a95ad7dd..3c1b77474d2d 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index b3e0d40932e1..e52dd37ddadc 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/os-Linux/registers.c b/arch/um/os-Linux/registers.c
index 2ff8d4fe83c4..2d9270508e15 100644
--- a/arch/um/os-Linux/registers.c
+++ b/arch/um/os-Linux/registers.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2004 PathScale, Inc
  * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <errno.h>
diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c
index 46e762f926eb..75558080d0bf 100644
--- a/arch/um/os-Linux/sigio.c
+++ b/arch/um/os-Linux/sigio.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <unistd.h>
@@ -132,7 +132,7 @@ static void update_thread(void)
 	int n;
 	char c;
 
-	flags = set_signals(0);
+	flags = set_signals_trace(0);
 	CATCH_EINTR(n = write(sigio_private[0], &c, sizeof(c)));
 	if (n != sizeof(c)) {
 		printk(UM_KERN_ERR "update_thread : write failed, err = %d\n",
@@ -147,7 +147,7 @@ static void update_thread(void)
 		goto fail;
 	}
 
-	set_signals(flags);
+	set_signals_trace(flags);
 	return;
  fail:
 	/* Critical section start */
@@ -161,7 +161,7 @@ static void update_thread(void)
 	close(write_sigio_fds[0]);
 	close(write_sigio_fds[1]);
 	/* Critical section end */
-	set_signals(flags);
+	set_signals_trace(flags);
 }
 
 int add_sigio_fd(int fd)
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 75b10235d369..b58bc68cbe64 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -1,15 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2004 PathScale, Inc
  * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdlib.h>
 #include <stdarg.h>
 #include <errno.h>
 #include <signal.h>
+#include <string.h>
 #include <strings.h>
 #include <as-layout.h>
 #include <kern_util.h>
@@ -26,7 +27,6 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = {
 	[SIGBUS]	= bus_handler,
 	[SIGSEGV]	= segv_handler,
 	[SIGIO]		= sigio_handler,
-	[SIGALRM]	= timer_handler
 };
 
 static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
@@ -42,8 +42,8 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
 	}
 
 	/* enable signals if sig isn't IRQ signal */
-	if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGALRM))
-		unblock_signals();
+	if ((sig != SIGIO) && (sig != SIGWINCH))
+		unblock_signals_trace();
 
 	(*sig_info[sig])(sig, si, &r);
 
@@ -76,11 +76,11 @@ void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
 		return;
 	}
 
-	block_signals();
+	block_signals_trace();
 
 	sig_handler_common(sig, si, mc);
 
-	set_signals(enabled);
+	set_signals_trace(enabled);
 }
 
 static void timer_real_alarm_handler(mcontext_t *mc)
@@ -89,6 +89,8 @@ static void timer_real_alarm_handler(mcontext_t *mc)
 
 	if (mc != NULL)
 		get_regs_from_mc(&regs, mc);
+	else
+		memset(&regs, 0, sizeof(regs));
 	timer_handler(SIGALRM, NULL, &regs);
 }
 
@@ -102,7 +104,7 @@ void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
 		return;
 	}
 
-	block_signals();
+	block_signals_trace();
 
 	signals_active |= SIGALRM_MASK;
 
@@ -110,7 +112,7 @@ void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
 
 	signals_active &= ~SIGALRM_MASK;
 
-	set_signals(enabled);
+	set_signals_trace(enabled);
 }
 
 void deliver_alarm(void) {
@@ -251,6 +253,8 @@ void unblock_signals(void)
 	if (signals_enabled == 1)
 		return;
 
+	signals_enabled = 1;
+
 	/*
 	 * We loop because the IRQ handler returns with interrupts off.  So,
 	 * interrupts may have arrived and we need to re-enable them and
@@ -260,12 +264,9 @@ void unblock_signals(void)
 		/*
 		 * Save and reset save_pending after enabling signals.  This
 		 * way, signals_pending won't be changed while we're reading it.
-		 */
-		signals_enabled = 1;
-
-		/*
+		 *
 		 * Setting signals_enabled and reading signals_pending must
-		 * happen in this order.
+		 * happen in this order, so have the barrier here.
 		 */
 		barrier();
 
@@ -278,10 +279,13 @@ void unblock_signals(void)
 		/*
 		 * We have pending interrupts, so disable signals, as the
 		 * handlers expect them off when they are called.  They will
-		 * be enabled again above.
+		 * be enabled again above. We need to trace this, as we're
+		 * expected to be enabling interrupts already, but any more
+		 * tracing that happens inside the handlers we call for the
+		 * pending signals will mess up the tracing state.
 		 */
-
 		signals_enabled = 0;
+		um_trace_signals_off();
 
 		/*
 		 * Deal with SIGIO first because the alarm handler might
@@ -304,6 +308,9 @@ void unblock_signals(void)
 		if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK))
 			return;
 
+		/* Re-enable signals and trace that we're doing so. */
+		um_trace_signals_on();
+		signals_enabled = 1;
 	}
 }
 
@@ -326,6 +333,21 @@ int set_signals(int enable)
 	return ret;
 }
 
+int set_signals_trace(int enable)
+{
+	int ret;
+	if (signals_enabled == enable)
+		return enable;
+
+	ret = signals_enabled;
+	if (enable)
+		unblock_signals_trace();
+	else
+		block_signals_trace();
+
+	return ret;
+}
+
 int os_is_signal_stack(void)
 {
 	stack_t ss;
diff --git a/arch/um/os-Linux/skas/Makefile b/arch/um/os-Linux/skas/Makefile
index d2ea3409e072..c4566e788815 100644
--- a/arch/um/os-Linux/skas/Makefile
+++ b/arch/um/os-Linux/skas/Makefile
@@ -1,6 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Copyright (C) 2002 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
-# Licensed under the GPL
 #
 
 obj-y := mem.o process.o
diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index 35015e3e1e87..c546d16f8dfe 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stddef.h>
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index df4a985716eb..4fb877b99dde 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -1,7 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdlib.h>
@@ -425,9 +425,9 @@ void userspace(struct uml_pt_regs *regs, unsigned long *aux_fp_regs)
 			case SIGBUS:
 			case SIGFPE:
 			case SIGWINCH:
-				block_signals();
+				block_signals_trace();
 				(*sig_info[sig])(sig, (struct siginfo *)&si, regs);
-				unblock_signals();
+				unblock_signals_trace();
 				break;
 			default:
 				printk(UM_KERN_ERR "userspace - child stopped "
@@ -625,10 +625,10 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 	cb_arg = arg;
 	cb_back = &here;
 
-	block_signals();
+	block_signals_trace();
 	if (UML_SETJMP(&here) == 0)
 		UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
-	unblock_signals();
+	unblock_signals_trace();
 
 	cb_proc = NULL;
 	cb_arg = NULL;
@@ -637,13 +637,13 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 
 void halt_skas(void)
 {
-	block_signals();
+	block_signals_trace();
 	UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
 }
 
 void reboot_skas(void)
 {
-	block_signals();
+	block_signals_trace();
 	UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
 }
 
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 82bf5f8442ba..f79dc338279e 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
index 6d94ff52362c..432f8e1f55c2 100644
--- a/arch/um/os-Linux/time.c
+++ b/arch/um/os-Linux/time.c
@@ -1,9 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2012-2014 Cisco Systems
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stddef.h>
diff --git a/arch/um/os-Linux/tty.c b/arch/um/os-Linux/tty.c
index 721d8afa329b..f784db83e026 100644
--- a/arch/um/os-Linux/tty.c
+++ b/arch/um/os-Linux/tty.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdlib.h>
diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
index e261656fe9d7..44def53a11cd 100644
--- a/arch/um/os-Linux/umid.c
+++ b/arch/um/os-Linux/umid.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index 8cc8b2617a67..ecf2f390fad2 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -1,6 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
- * Licensed under the GPL
  */
 
 #include <stdio.h>
diff --git a/arch/x86/um/asm/barrier.h b/arch/x86/um/asm/barrier.h
index f31e5d903161..165be7f9a964 100644
--- a/arch/x86/um/asm/barrier.h
+++ b/arch/x86/um/asm/barrier.h
@@ -2,14 +2,7 @@
 #ifndef _ASM_UM_BARRIER_H_
 #define _ASM_UM_BARRIER_H_
 
-#include <asm/asm.h>
-#include <asm/segment.h>
-#include <asm/cpufeatures.h>
-#include <asm/cmpxchg.h>
-#include <asm/nops.h>
-
-#include <linux/kernel.h>
-#include <linux/irqflags.h>
+#include <asm/alternative.h>
 
 /*
  * Force strict CPU ordering.
@@ -30,9 +23,6 @@
 
 #endif /* CONFIG_X86_32 */
 
-#define dma_rmb()	barrier()
-#define dma_wmb()	barrier()
-
 #include <asm-generic/barrier.h>
 
 #endif
diff --git a/arch/x86/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c
index ac9c02b9d92c..891868756a51 100644
--- a/arch/x86/um/vdso/um_vdso.c
+++ b/arch/x86/um/vdso/um_vdso.c
@@ -47,7 +47,7 @@ time_t __vdso_time(time_t *t)
 
 	return secs;
 }
-int time(time_t *t) __attribute__((weak, alias("__vdso_time")));
+time_t time(time_t *t) __attribute__((weak, alias("__vdso_time")));
 
 long
 __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
diff --git a/init/Kconfig b/init/Kconfig
index 7020238fd263..058ba4e74250 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -54,7 +54,6 @@ config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
 
 config CONSTRUCTORS
 	bool
-	depends on !UML
 
 config IRQ_WORK
 	bool
diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
index 3941a9c48f83..060e8e726755 100644
--- a/kernel/gcov/Kconfig
+++ b/kernel/gcov/Kconfig
@@ -4,7 +4,7 @@ menu "GCOV-based kernel profiling"
 config GCOV_KERNEL
 	bool "Enable gcov-based kernel profiling"
 	depends on DEBUG_FS
-	select CONSTRUCTORS if !UML
+	select CONSTRUCTORS
 	default n
 	---help---
 	This option enables gcov-based code profiling (e.g. for code coverage