Merge tag 'for-linus-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

Pull UML updates from Richard Weinberger:

 - IRQ handling cleanups

 - Support for suspend

 - Various fixes for UML specific drivers: ubd, vector, xterm

* tag 'for-linus-5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: (32 commits)
  um: Fix build w/o CONFIG_PM_SLEEP
  um: time-travel: Correct time event IRQ delivery
  um: irq/sigio: Support suspend/resume handling of workaround IRQs
  um: time-travel: Actually apply "free-until" optimisation
  um: chan_xterm: Fix fd leak
  um: tty: Fix handling of close in tty lines
  um: Monitor error events in IRQ controller
  um: allocate a guard page to helper threads
  um: support some of ARCH_HAS_SET_MEMORY
  um: time-travel: avoid multiple identical propagations
  um: Fetch registers only for signals which need them
  um: Support suspend to RAM
  um: Allow PM with suspend-to-idle
  um: time: Fix read_persistent_clock64() in time-travel
  um: Simplify os_idle_sleep() and sleep longer
  um: Simplify IRQ handling code
  um: Remove IRQ_NONE type
  um: irq: Reduce irq_reg allocation
  um: irq: Clean up and rename struct irq_fd
  um: Clean up alarm IRQ chip name
  ...

arch/um/Kconfig

@@ -15,6 +15,7 @@ config UML
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DEBUG_BUGVERBOSE
 	select NO_DMA
+	select ARCH_HAS_SET_MEMORY
 	select GENERIC_IRQ_SHOW
 	select GENERIC_CPU_DEVICES
 	select HAVE_GCC_PLUGINS
@@ -191,3 +192,8 @@ config UML_TIME_TRAVEL_SUPPORT
 endmenu
 
 source "arch/um/drivers/Kconfig"
+
+config ARCH_SUSPEND_POSSIBLE
+	def_bool y
+
+source "kernel/power/Kconfig"

arch/um/drivers/chan_user.c

@@ -26,10 +26,10 @@ int generic_read(int fd, char *c_out, void *unused)
 	n = read(fd, c_out, sizeof(*c_out));
 	if (n > 0)
 		return n;
-	else if (errno == EAGAIN)
-		return 0;
 	else if (n == 0)
 		return -EIO;
+	else if (errno == EAGAIN)
+		return 0;
 	return -errno;
 }
 

arch/um/drivers/line.c

@@ -262,19 +262,25 @@ static irqreturn_t line_write_interrupt(int irq, void *data)
 int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
 {
 	const struct line_driver *driver = line->driver;
-	int err = 0;
+	int err;
 
-	if (input)
+	if (input) {
 		err = um_request_irq(driver->read_irq, fd, IRQ_READ,
 				     line_interrupt, IRQF_SHARED,
 				     driver->read_irq_name, data);
-	if (err)
+		if (err < 0)
 			return err;
-	if (output)
+	}
+
+	if (output) {
 		err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
 				     line_write_interrupt, IRQF_SHARED,
 				     driver->write_irq_name, data);
+		if (err < 0)
 			return err;
+	}
+
+	return 0;
 }
 
 static int line_activate(struct tty_port *port, struct tty_struct *tty)
@@ -608,7 +614,6 @@ static void free_winch(struct winch *winch)
 	winch->fd = -1;
 	if (fd != -1)
 		os_close_file(fd);
-	list_del(&winch->list);
 	__free_winch(&winch->work);
 }
 
@@ -709,6 +714,8 @@ static void unregister_winch(struct tty_struct *tty)
 		winch = list_entry(ele, struct winch, list);
 		wtty = tty_port_tty_get(winch->port);
 		if (wtty == tty) {
+			list_del(&winch->list);
+			spin_unlock(&winch_handler_lock);
 			free_winch(winch);
 			break;
 		}
@@ -719,14 +726,17 @@ static void unregister_winch(struct tty_struct *tty)
 
 static void winch_cleanup(void)
 {
-	struct list_head *ele, *next;
 	struct winch *winch;
 
 	spin_lock(&winch_handler_lock);
+	while ((winch = list_first_entry_or_null(&winch_handlers,
+						 struct winch, list))) {
+		list_del(&winch->list);
+		spin_unlock(&winch_handler_lock);
 
-	list_for_each_safe(ele, next, &winch_handlers) {
-		winch = list_entry(ele, struct winch, list);
 		free_winch(winch);
+
+		spin_lock(&winch_handler_lock);
 	}
 
 	spin_unlock(&winch_handler_lock);

arch/um/drivers/mconsole_kern.c

@@ -738,7 +738,7 @@ static int __init mconsole_init(void)
 
 	err = um_request_irq(MCONSOLE_IRQ, sock, IRQ_READ, mconsole_interrupt,
 			     IRQF_SHARED, "mconsole", (void *)sock);
-	if (err) {
+	if (err < 0) {
 		printk(KERN_ERR "Failed to get IRQ for management console\n");
 		goto out;
 	}

arch/um/drivers/net_kern.c

@@ -160,7 +160,7 @@ static int uml_net_open(struct net_device *dev)
 
 	err = um_request_irq(dev->irq, lp->fd, IRQ_READ, uml_net_interrupt,
 			     IRQF_SHARED, dev->name, dev);
-	if (err != 0) {
+	if (err < 0) {
 		printk(KERN_ERR "uml_net_open: failed to get irq(%d)\n", err);
 		err = -ENETUNREACH;
 		goto out_close;

arch/um/drivers/port_kern.c

@@ -100,7 +100,7 @@ static int port_accept(struct port_list *port)
 		  .port 	= port });
 
 	if (um_request_irq(TELNETD_IRQ, socket[0], IRQ_READ, pipe_interrupt,
-			  IRQF_SHARED, "telnetd", conn)) {
+			  IRQF_SHARED, "telnetd", conn) < 0) {
 		printk(KERN_ERR "port_accept : failed to get IRQ for "
 		       "telnetd\n");
 		goto out_free;
@@ -182,7 +182,7 @@ void *port_data(int port_num)
 	}
 
 	if (um_request_irq(ACCEPT_IRQ, fd, IRQ_READ, port_interrupt,
-			  IRQF_SHARED, "port", port)) {
+			  IRQF_SHARED, "port", port) < 0) {
 		printk(KERN_ERR "Failed to get IRQ for port %d\n", port_num);
 		goto out_close;
 	}

arch/um/drivers/random.c

@@ -11,6 +11,7 @@
 #include <linux/fs.h>
 #include <linux/interrupt.h>
 #include <linux/miscdevice.h>
+#include <linux/hw_random.h>
 #include <linux/delay.h>
 #include <linux/uaccess.h>
 #include <init.h>
@@ -18,9 +19,8 @@
 #include <os.h>
 
 /*
- * core module and version information
+ * core module information
  */
-#define RNG_VERSION "1.0.0"
 #define RNG_MODULE_NAME "hw_random"
 
 /* Changed at init time, in the non-modular case, and at module load
@@ -28,88 +28,36 @@
  * protects against a module being loaded twice at the same time.
  */
 static int random_fd = -1;
-static DECLARE_WAIT_QUEUE_HEAD(host_read_wait);
+static struct hwrng hwrng = { 0, };
+static DECLARE_COMPLETION(have_data);
 
-static int rng_dev_open (struct inode *inode, struct file *filp)
+static int rng_dev_read(struct hwrng *rng, void *buf, size_t max, bool block)
 {
-	/* enforce read-only access to this chrdev */
-	if ((filp->f_mode & FMODE_READ) == 0)
-		return -EINVAL;
-	if ((filp->f_mode & FMODE_WRITE) != 0)
-		return -EINVAL;
+	int ret;
 
-	return 0;
-}
-
-static atomic_t host_sleep_count = ATOMIC_INIT(0);
-
-static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size,
-			     loff_t *offp)
-{
-	u32 data;
-	int n, ret = 0, have_data;
-
-	while (size) {
-		n = os_read_file(random_fd, &data, sizeof(data));
-		if (n > 0) {
-			have_data = n;
-			while (have_data && size) {
-				if (put_user((u8) data, buf++)) {
-					ret = ret ? : -EFAULT;
-					break;
-				}
-				size--;
-				ret++;
-				have_data--;
-				data >>= 8;
-			}
-		}
-		else if (n == -EAGAIN) {
-			DECLARE_WAITQUEUE(wait, current);
-
-			if (filp->f_flags & O_NONBLOCK)
-				return ret ? : -EAGAIN;
-
-			atomic_inc(&host_sleep_count);
+	for (;;) {
+		ret = os_read_file(random_fd, buf, max);
+		if (block && ret == -EAGAIN) {
 			add_sigio_fd(random_fd);
 
-			add_wait_queue(&host_read_wait, &wait);
-			set_current_state(TASK_INTERRUPTIBLE);
+			ret = wait_for_completion_killable(&have_data);
 
-			schedule();
-			remove_wait_queue(&host_read_wait, &wait);
-
-			if (atomic_dec_and_test(&host_sleep_count)) {
 			ignore_sigio_fd(random_fd);
 			deactivate_fd(random_fd, RANDOM_IRQ);
+
+			if (ret < 0)
+				break;
+		} else {
+			break;
 		}
 	}
-		else
-			return n;
 
-		if (signal_pending (current))
-			return ret ? : -ERESTARTSYS;
-	}
-	return ret;
+	return ret != -EAGAIN ? ret : 0;
 }
 
-static const struct file_operations rng_chrdev_ops = {
-	.owner		= THIS_MODULE,
-	.open		= rng_dev_open,
-	.read		= rng_dev_read,
-	.llseek		= noop_llseek,
-};
-
-/* rng_init shouldn't be called more than once at boot time */
-static struct miscdevice rng_miscdev = {
-	HWRNG_MINOR,
-	RNG_MODULE_NAME,
-	&rng_chrdev_ops,
-};
-
 static irqreturn_t random_interrupt(int irq, void *data)
 {
-	wake_up(&host_read_wait);
+	complete(&have_data);
 
 	return IRQ_HANDLED;
 }
@@ -126,18 +74,19 @@ static int __init rng_init (void)
 		goto out;
 
 	random_fd = err;
-
 	err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt,
 			     0, "random", NULL);
-	if (err)
+	if (err < 0)
 		goto err_out_cleanup_hw;
 
-	sigio_broken(random_fd, 1);
+	sigio_broken(random_fd);
+	hwrng.name = RNG_MODULE_NAME;
+	hwrng.read = rng_dev_read;
+	hwrng.quality = 1024;
 
-	err = misc_register (&rng_miscdev);
+	err = hwrng_register(&hwrng);
 	if (err) {
-		printk (KERN_ERR RNG_MODULE_NAME ": misc device register "
-			"failed\n");
+		pr_err(RNG_MODULE_NAME " registering failed (%d)\n", err);
 		goto err_out_cleanup_hw;
 	}
 out:
@@ -161,8 +110,8 @@ static void cleanup(void)
 
 static void __exit rng_cleanup(void)
 {
+	hwrng_unregister(&hwrng);
 	os_close_file(random_fd);
-	misc_deregister (&rng_miscdev);
 }
 
 module_init (rng_init);

arch/um/drivers/vector_kern.c

@@ -1196,9 +1196,9 @@ static int vector_net_close(struct net_device *dev)
 
 /* TX tasklet */
 
-static void vector_tx_poll(unsigned long data)
+static void vector_tx_poll(struct tasklet_struct *t)
 {
-	struct vector_private *vp = (struct vector_private *)data;
+	struct vector_private *vp = from_tasklet(vp, t, tx_poll);
 
 	vp->estats.tx_kicks++;
 	vector_send(vp->tx_queue);
@@ -1271,7 +1271,7 @@ static int vector_net_open(struct net_device *dev)
 		irq_rr + VECTOR_BASE_IRQ, vp->fds->rx_fd,
 			IRQ_READ, vector_rx_interrupt,
 			IRQF_SHARED, dev->name, dev);
-	if (err != 0) {
+	if (err < 0) {
 		netdev_err(dev, "vector_open: failed to get rx irq(%d)\n", err);
 		err = -ENETUNREACH;
 		goto out_close;
@@ -1286,7 +1286,7 @@ static int vector_net_open(struct net_device *dev)
 			irq_rr + VECTOR_BASE_IRQ, vp->fds->tx_fd,
 				IRQ_WRITE, vector_tx_interrupt,
 				IRQF_SHARED, dev->name, dev);
-		if (err != 0) {
+		if (err < 0) {
 			netdev_err(dev,
 				"vector_open: failed to get tx irq(%d)\n", err);
 			err = -ENETUNREACH;
@@ -1629,7 +1629,7 @@ static void vector_eth_configure(
 	});
 
 	dev->features = dev->hw_features = (NETIF_F_SG | NETIF_F_FRAGLIST);
-	tasklet_init(&vp->tx_poll, vector_tx_poll, (unsigned long)vp);
+	tasklet_setup(&vp->tx_poll, vector_tx_poll);
 	INIT_WORK(&vp->reset_tx, vector_reset_tx);
 
 	timer_setup(&vp->tl, vector_timer_expire, 0);

arch/um/drivers/virtio_uml.c

@@ -33,11 +33,6 @@
 #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) \
@@ -55,7 +50,7 @@ struct virtio_uml_device {
 	struct platform_device *pdev;
 
 	spinlock_t sock_lock;
-	int sock, req_fd;
+	int sock, req_fd, irq;
 	u64 features;
 	u64 protocol_features;
 	u8 status;
@@ -409,12 +404,14 @@ static int vhost_user_init_slave_req(struct virtio_uml_device *vu_dev)
 		return rc;
 	vu_dev->req_fd = req_fds[0];
 
-	rc = um_request_irq(VIRTIO_IRQ, vu_dev->req_fd, IRQ_READ,
+	rc = um_request_irq(UM_IRQ_ALLOC, vu_dev->req_fd, IRQ_READ,
 			    vu_req_interrupt, IRQF_SHARED,
 			    vu_dev->pdev->name, vu_dev);
-	if (rc)
+	if (rc < 0)
 		goto err_close;
 
+	vu_dev->irq = rc;
+
 	rc = vhost_user_send_no_payload_fd(vu_dev, VHOST_USER_SET_SLAVE_REQ_FD,
 					   req_fds[1]);
 	if (rc)
@@ -423,7 +420,7 @@ static int vhost_user_init_slave_req(struct virtio_uml_device *vu_dev)
 	goto out;
 
 err_free_irq:
-	um_free_irq(VIRTIO_IRQ, vu_dev);
+	um_free_irq(vu_dev->irq, vu_dev);
 err_close:
 	os_close_file(req_fds[0]);
 out:
@@ -802,7 +799,11 @@ static void vu_del_vq(struct virtqueue *vq)
 	struct virtio_uml_vq_info *info = vq->priv;
 
 	if (info->call_fd >= 0) {
-		um_free_irq(VIRTIO_IRQ, vq);
+		struct virtio_uml_device *vu_dev;
+
+		vu_dev = to_virtio_uml_device(vq->vdev);
+
+		um_free_irq(vu_dev->irq, vq);
 		os_close_file(info->call_fd);
 	}
 
@@ -852,9 +853,9 @@ static int vu_setup_vq_call_fd(struct virtio_uml_device *vu_dev,
 		return rc;
 
 	info->call_fd = call_fds[0];
-	rc = um_request_irq(VIRTIO_IRQ, info->call_fd, IRQ_READ,
+	rc = um_request_irq(vu_dev->irq, info->call_fd, IRQ_READ,
 			    vu_interrupt, IRQF_SHARED, info->name, vq);
-	if (rc)
+	if (rc < 0)
 		goto close_both;
 
 	rc = vhost_user_set_vring_call(vu_dev, vq->index, call_fds[1]);
@@ -864,7 +865,7 @@ static int vu_setup_vq_call_fd(struct virtio_uml_device *vu_dev,
 	goto out;
 
 release_irq:
-	um_free_irq(VIRTIO_IRQ, vq);
+	um_free_irq(vu_dev->irq, vq);
 close_both:
 	os_close_file(call_fds[0]);
 out:
@@ -969,7 +970,7 @@ static struct virtqueue *vu_setup_vq(struct virtio_device *vdev,
 
 error_setup:
 	if (info->call_fd >= 0) {
-		um_free_irq(VIRTIO_IRQ, vq);
+		um_free_irq(vu_dev->irq, vq);
 		os_close_file(info->call_fd);
 	}
 error_call:
@@ -1078,7 +1079,7 @@ static void virtio_uml_release_dev(struct device *d)
 
 	/* might not have been opened due to not negotiating the feature */
 	if (vu_dev->req_fd >= 0) {
-		um_free_irq(VIRTIO_IRQ, vu_dev);
+		um_free_irq(vu_dev->irq, vu_dev);
 		os_close_file(vu_dev->req_fd);
 	}
 

arch/um/drivers/xterm.c

@@ -18,6 +18,7 @@
 struct xterm_chan {
 	int pid;
 	int helper_pid;
+	int chan_fd;
 	char *title;
 	int device;
 	int raw;
@@ -33,6 +34,7 @@ static void *xterm_init(char *str, int device, const struct chan_opts *opts)
 		return NULL;
 	*data = ((struct xterm_chan) { .pid 		= -1,
 				       .helper_pid 	= -1,
+				       .chan_fd		= -1,
 				       .device 		= device,
 				       .title 		= opts->xterm_title,
 				       .raw  		= opts->raw } );
@@ -149,6 +151,7 @@ static int xterm_open(int input, int output, int primary, void *d,
 		goto out_kill;
 	}
 
+	data->chan_fd = fd;
 	new = xterm_fd(fd, &data->helper_pid);
 	if (new < 0) {
 		err = new;
@@ -206,6 +209,8 @@ static void xterm_close(int fd, void *d)
 		os_kill_process(data->helper_pid, 0);
 	data->helper_pid = -1;
 
+	if (data->chan_fd != -1)
+		os_close_file(data->chan_fd);
 	os_close_file(fd);
 }
 

arch/um/drivers/xterm_kern.c

@@ -51,7 +51,7 @@ int xterm_fd(int socket, int *pid_out)
 
 	err = um_request_irq(XTERM_IRQ, socket, IRQ_READ, xterm_interrupt,
 			     IRQF_SHARED, "xterm", data);
-	if (err) {
+	if (err < 0) {
 		printk(KERN_ERR "xterm_fd : failed to get IRQ for xterm, "
 		       "err = %d\n",  err);
 		ret = err;

arch/um/include/asm/irq.h

@@ -17,21 +17,20 @@
 #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		(VIRTIO_IRQ + 1)
+#define VECTOR_BASE_IRQ		(RANDOM_IRQ + 1)
 #define VECTOR_IRQ_SPACE	8
 
-#define LAST_IRQ (VECTOR_IRQ_SPACE + VECTOR_BASE_IRQ - 1)
+#define UM_FIRST_DYN_IRQ (VECTOR_IRQ_SPACE + VECTOR_BASE_IRQ)
 
 #else
 
-#define LAST_IRQ VIRTIO_IRQ
+#define UM_FIRST_DYN_IRQ (RANDOM_IRQ + 1)
 
 #endif
 
-#define NR_IRQS (LAST_IRQ + 1)
+#define NR_IRQS			64
 
 #endif

arch/um/include/asm/pgtable.h

@@ -55,12 +55,15 @@ extern unsigned long end_iomem;
 #define _PAGE_CHG_MASK	(PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
 #define __PAGE_KERNEL_EXEC                                              \
 	 (_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
+#define __PAGE_KERNEL_RO						\
+	 (_PAGE_PRESENT | _PAGE_DIRTY | _PAGE_ACCESSED)
 #define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
 #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED)
 #define PAGE_COPY	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
 #define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
 #define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
 #define PAGE_KERNEL_EXEC	__pgprot(__PAGE_KERNEL_EXEC)
+#define PAGE_KERNEL_RO		__pgprot(__PAGE_KERNEL_RO)
 
 /*
  * The i386 can't do page protection for execute, and considers that the same

arch/um/include/asm/set_memory.h

+#include <asm-generic/set_memory.h>

arch/um/include/linux/time-internal.h

@@ -28,7 +28,7 @@ struct time_travel_event {
 
 extern enum time_travel_mode time_travel_mode;
 
-void time_travel_sleep(unsigned long long duration);
+void time_travel_sleep(void);
 
 static inline void
 time_travel_set_event_fn(struct time_travel_event *e,
@@ -60,7 +60,7 @@ struct time_travel_event {
 
 #define time_travel_mode TT_MODE_OFF
 
-static inline void time_travel_sleep(unsigned long long duration)
+static inline void time_travel_sleep(void)
 {
 }
 

arch/um/include/shared/common-offsets.h

@@ -40,3 +40,6 @@ DEFINE(UML_CONFIG_UML_X86, CONFIG_UML_X86);
 #ifdef CONFIG_64BIT
 DEFINE(UML_CONFIG_64BIT, CONFIG_64BIT);
 #endif
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+DEFINE(UML_CONFIG_UML_TIME_TRAVEL_SUPPORT, CONFIG_UML_TIME_TRAVEL_SUPPORT);
+#endif

arch/um/include/shared/irq_kern.h

@@ -8,11 +8,12 @@
 
 #include <linux/interrupt.h>
 #include <asm/ptrace.h>
+#include "irq_user.h"
 
-extern int um_request_irq(unsigned int irq, int fd, int type,
-			  irq_handler_t handler,
-			  unsigned long irqflags,  const char * devname,
-			  void *dev_id);
-void um_free_irq(unsigned int irq, void *dev);
-#endif
+#define UM_IRQ_ALLOC	-1
 
+int um_request_irq(int irq, int fd, enum um_irq_type type,
+		   irq_handler_t handler, unsigned long irqflags,
+		   const char *devname, void *dev_id);
+void um_free_irq(int irq, void *dev_id);
+#endif

arch/um/include/shared/irq_user.h

@@ -9,25 +9,12 @@
 #include <sysdep/ptrace.h>
 #include <stdbool.h>
 
-struct irq_fd {
-	struct irq_fd *next;
-	void *id;
-	int fd;
-	int type;
-	int irq;
-	int events;
-	bool active;
-	bool pending;
-	bool purge;
+enum um_irq_type {
+	IRQ_READ,
+	IRQ_WRITE,
+	NUM_IRQ_TYPES,
 };
 
-#define IRQ_READ  0
-#define IRQ_WRITE 1
-#define IRQ_NONE 2
-#define MAX_IRQ_TYPE (IRQ_NONE + 1)
-
-
-
 struct siginfo;
 extern void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
 extern void free_irq_by_fd(int fd);

arch/um/include/shared/kern_util.h

@@ -19,7 +19,7 @@ extern int kmalloc_ok;
 #define UML_ROUND_UP(addr) \
 	((((unsigned long) addr) + PAGE_SIZE - 1) & PAGE_MASK)
 
-extern unsigned long alloc_stack(int order, int atomic);
+extern unsigned long alloc_stack(int atomic);
 extern void free_stack(unsigned long stack, int order);
 
 struct pt_regs;
@@ -39,6 +39,8 @@ extern int is_syscall(unsigned long addr);
 
 extern void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
 
+extern void uml_pm_wake(void);
+
 extern int start_uml(void);
 extern void paging_init(void);
 
@@ -66,5 +68,6 @@ extern void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs);
 extern void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
 extern void fatal_sigsegv(void) __attribute__ ((noreturn));
 
+void um_idle_sleep(void);
 
 #endif

arch/um/include/shared/os.h

@@ -233,6 +233,7 @@ extern void timer_set_signal_handler(void);
 extern void set_sigstack(void *sig_stack, int size);
 extern void remove_sigstack(void);
 extern void set_handler(int sig);
+extern void send_sigio_to_self(void);
 extern int change_sig(int signal, int on);
 extern void block_signals(void);
 extern void unblock_signals(void);
@@ -241,6 +242,7 @@ 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);
+extern void register_pm_wake_signal(void);
 
 /* util.c */
 extern void stack_protections(unsigned long address);
@@ -256,7 +258,7 @@ extern void os_warn(const char *fmt, ...)
 	__attribute__ ((format (printf, 1, 2)));
 
 /* time.c */
-extern void os_idle_sleep(unsigned long long nsecs);
+extern void os_idle_sleep(void);
 extern int os_timer_create(void);
 extern int os_timer_set_interval(unsigned long long nsecs);
 extern int os_timer_one_shot(unsigned long long nsecs);
@@ -299,19 +301,29 @@ extern void reboot_skas(void);
 extern int os_waiting_for_events_epoll(void);
 extern void *os_epoll_get_data_pointer(int index);
 extern int os_epoll_triggered(int index, int events);
-extern int os_event_mask(int irq_type);
+extern int os_event_mask(enum um_irq_type irq_type);
 extern int os_setup_epoll(void);
 extern int os_add_epoll_fd(int events, int fd, void *data);
 extern int os_mod_epoll_fd(int events, int fd, void *data);
 extern int os_del_epoll_fd(int fd);
 extern void os_set_ioignore(void);
 extern void os_close_epoll_fd(void);
+extern void um_irqs_suspend(void);
+extern void um_irqs_resume(void);
 
 /* sigio.c */
 extern int add_sigio_fd(int fd);
 extern int ignore_sigio_fd(int fd);
-extern void maybe_sigio_broken(int fd, int read);
-extern void sigio_broken(int fd, int read);
+extern void maybe_sigio_broken(int fd);
+extern void sigio_broken(int fd);
+/*
+ * unlocked versions for IRQ controller code.
+ *
+ * This is safe because it's used at suspend/resume and nothing
+ * else is running.
+ */
+extern int __add_sigio_fd(int fd);
+extern int __ignore_sigio_fd(int fd);
 
 /* prctl.c */
 extern int os_arch_prctl(int pid, int option, unsigned long *arg2);
@@ -330,4 +342,7 @@ extern void unblock_signals_trace(void);
 extern void um_trace_signals_on(void);
 extern void um_trace_signals_off(void);
 
+/* time-travel */
+extern void deliver_time_travel_irqs(void);
+
 #endif

arch/um/kernel/process.c

@@ -32,6 +32,7 @@
 #include <os.h>
 #include <skas.h>
 #include <linux/time-internal.h>
+#include <asm/set_memory.h>
 
 /*
  * This is a per-cpu array.  A processor only modifies its entry and it only
@@ -62,16 +63,18 @@ void free_stack(unsigned long stack, int order)
 	free_pages(stack, order);
 }
 
-unsigned long alloc_stack(int order, int atomic)
+unsigned long alloc_stack(int atomic)
 {
-	unsigned long page;
+	unsigned long addr;
 	gfp_t flags = GFP_KERNEL;
 
 	if (atomic)
 		flags = GFP_ATOMIC;
-	page = __get_free_pages(flags, order);
+	addr = __get_free_pages(flags, 1);
 
-	return page;
+	set_memory_ro(addr, 1);
+
+	return addr + PAGE_SIZE;
 }
 
 static inline void set_current(struct task_struct *task)
@@ -203,15 +206,12 @@ void initial_thread_cb(void (*proc)(void *), void *arg)
 	kmalloc_ok = save_kmalloc_ok;
 }
 
-static void um_idle_sleep(void)
+void um_idle_sleep(void)
 {
-	unsigned long long duration = UM_NSEC_PER_SEC;
-
-	if (time_travel_mode != TT_MODE_OFF) {
-		time_travel_sleep(duration);
-	} else {
-		os_idle_sleep(duration);
-	}
+	if (time_travel_mode != TT_MODE_OFF)
+		time_travel_sleep();
+	else
+		os_idle_sleep();
 }
 
 void arch_cpu_idle(void)

arch/um/kernel/sigio.c

@@ -25,7 +25,7 @@ int write_sigio_irq(int fd)
 
 	err = um_request_irq(SIGIO_WRITE_IRQ, fd, IRQ_READ, sigio_interrupt,
 			     0, "write sigio", NULL);
-	if (err) {
+	if (err < 0) {
 		printk(KERN_ERR "write_sigio_irq : um_request_irq failed, "
 		       "err = %d\n", err);
 		return -1;

arch/um/kernel/time.c

@@ -31,6 +31,7 @@ static bool time_travel_start_set;
 static unsigned long long time_travel_start;
 static unsigned long long time_travel_time;
 static LIST_HEAD(time_travel_events);
+static LIST_HEAD(time_travel_irqs);
 static unsigned long long time_travel_timer_interval;
 static unsigned long long time_travel_next_event;
 static struct time_travel_event time_travel_timer_event;
@@ -46,6 +47,9 @@ static void time_travel_set_time(unsigned long long ns)
 	if (unlikely(ns < time_travel_time))
 		panic("time-travel: time goes backwards %lld -> %lld\n",
 		      time_travel_time, ns);
+	else if (unlikely(ns >= S64_MAX))
+		panic("The system was going to sleep forever, aborting");
+
 	time_travel_time = ns;
 }
 
@@ -180,6 +184,14 @@ static void time_travel_ext_update_request(unsigned long long time)
 	    time == time_travel_ext_prev_request)
 		return;
 
+	/*
+	 * if we're running and are allowed to run past the request
+	 * then we don't need to update it either
+	 */
+	if (!time_travel_ext_waiting && time_travel_ext_free_until_valid &&
+	    time < time_travel_ext_free_until)
+		return;
+
 	time_travel_ext_prev_request = time;
 	time_travel_ext_prev_request_valid = true;
 	time_travel_ext_req(UM_TIMETRAVEL_REQUEST, time);
@@ -187,7 +199,13 @@ static void time_travel_ext_update_request(unsigned long long time)
 
 void __time_travel_propagate_time(void)
 {
+	static unsigned long long last_propagated;
+
+	if (last_propagated == time_travel_time)
+		return;
+
 	time_travel_ext_req(UM_TIMETRAVEL_UPDATE, time_travel_time);
+	last_propagated = time_travel_time;
 }
 EXPORT_SYMBOL_GPL(__time_travel_propagate_time);
 
@@ -214,6 +232,7 @@ static void time_travel_ext_wait(bool idle)
 	};
 
 	time_travel_ext_prev_request_valid = false;
+	time_travel_ext_free_until_valid = false;
 	time_travel_ext_waiting++;
 
 	time_travel_ext_req(UM_TIMETRAVEL_WAIT, -1);
@@ -260,11 +279,6 @@ static void __time_travel_add_event(struct time_travel_event *e,
 	struct time_travel_event *tmp;
 	bool inserted = false;
 
-	if (WARN(time_travel_mode == TT_MODE_BASIC &&
-		 e != &time_travel_timer_event,
-		 "only timer events can be handled in basic mode"))
-		return;
-
 	if (e->pending)
 		return;
 
@@ -311,6 +325,35 @@ void time_travel_periodic_timer(struct time_travel_event *e)
 	deliver_alarm();
 }
 
+void deliver_time_travel_irqs(void)
+{
+	struct time_travel_event *e;
+	unsigned long flags;
+
+	/*
+	 * Don't do anything for most cases. Note that because here we have
+	 * to disable IRQs (and re-enable later) we'll actually recurse at
+	 * the end of the function, so this is strictly necessary.
+	 */
+	if (likely(list_empty(&time_travel_irqs)))
+		return;
+
+	local_irq_save(flags);
+	irq_enter();
+	while ((e = list_first_entry_or_null(&time_travel_irqs,
+					     struct time_travel_event,
+					     list))) {
+		WARN(e->time != time_travel_time,
+		     "time moved from %lld to %lld before IRQ delivery\n",
+		     time_travel_time, e->time);
+		list_del(&e->list);
+		e->pending = false;
+		e->fn(e);
+	}
+	irq_exit();
+	local_irq_restore(flags);
+}
+
 static void time_travel_deliver_event(struct time_travel_event *e)
 {
 	if (e == &time_travel_timer_event) {
@@ -319,6 +362,14 @@ static void time_travel_deliver_event(struct time_travel_event *e)
 		 * by itself, so must handle it specially here
 		 */
 		e->fn(e);
+	} else if (irqs_disabled()) {
+		list_add_tail(&e->list, &time_travel_irqs);
+		/*
+		 * set pending again, it was set to false when the
+		 * event was deleted from the original list, but
+		 * now it's still pending until we deliver the IRQ.
+		 */
+		e->pending = true;
 	} else {
 		unsigned long flags;
 
@@ -404,9 +455,14 @@ static void time_travel_oneshot_timer(struct time_travel_event *e)
 	deliver_alarm();
 }
 
-void time_travel_sleep(unsigned long long duration)
+void time_travel_sleep(void)
 {
-	unsigned long long next = time_travel_time + duration;
+	/*
+	 * Wait "forever" (using S64_MAX because there are some potential
+	 * wrapping issues, especially with the current TT_MODE_EXTERNAL
+	 * controller application.
+	 */
+	unsigned long long next = S64_MAX;
 
 	if (time_travel_mode == TT_MODE_BASIC)
 		os_timer_disable();
@@ -483,6 +539,7 @@ static int time_travel_connect_external(const char *socket)
 #define time_travel_start_set 0
 #define time_travel_start 0
 #define time_travel_time 0
+#define time_travel_ext_waiting 0
 
 static inline void time_travel_update_time(unsigned long long ns, bool retearly)
 {
@@ -628,7 +685,8 @@ static u64 timer_read(struct clocksource *cs)
 		 * "what do I do next" and onstack event we use to know when
 		 * to return from time_travel_update_time().
 		 */
-		if (!irqs_disabled() && !in_interrupt() && !in_softirq())
+		if (!irqs_disabled() && !in_interrupt() && !in_softirq() &&
+		    !time_travel_ext_waiting)
 			time_travel_update_time(time_travel_time +
 						TIMER_MULTIPLIER,
 						false);
@@ -673,10 +731,8 @@ void read_persistent_clock64(struct timespec64 *ts)
 {
 	long long nsecs;
 
-	if (time_travel_start_set)
+	if (time_travel_mode != TT_MODE_OFF)
 		nsecs = time_travel_start + time_travel_time;
-	else if (time_travel_mode == TT_MODE_EXTERNAL)
-		nsecs = time_travel_ext_req(UM_TIMETRAVEL_GET_TOD, -1);
 	else
 		nsecs = os_persistent_clock_emulation();
 
@@ -686,6 +742,25 @@ void read_persistent_clock64(struct timespec64 *ts)
 
 void __init time_init(void)
 {
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+	switch (time_travel_mode) {
+	case TT_MODE_EXTERNAL:
+		time_travel_start = time_travel_ext_req(UM_TIMETRAVEL_GET_TOD, -1);
+		/* controller gave us the *current* time, so adjust by that */
+		time_travel_ext_get_time();
+		time_travel_start -= time_travel_time;
+		break;
+	case TT_MODE_INFCPU:
+	case TT_MODE_BASIC:
+		if (!time_travel_start_set)
+			time_travel_start = os_persistent_clock_emulation();
+		break;
+	case TT_MODE_OFF:
+		/* we just read the host clock with os_persistent_clock_emulation() */
+		break;
+	}
+#endif
+
 	timer_set_signal_handler();
 	late_time_init = um_timer_setup;
 }

arch/um/kernel/tlb.c

@@ -608,3 +608,57 @@ void force_flush_all(void)
 		vma = vma->vm_next;
 	}
 }
+
+struct page_change_data {
+	unsigned int set_mask, clear_mask;
+};
+
+static int change_page_range(pte_t *ptep, unsigned long addr, void *data)
+{
+	struct page_change_data *cdata = data;
+	pte_t pte = READ_ONCE(*ptep);
+
+	pte_clear_bits(pte, cdata->clear_mask);
+	pte_set_bits(pte, cdata->set_mask);
+
+	set_pte(ptep, pte);
+	return 0;
+}
+
+static int change_memory(unsigned long start, unsigned long pages,
+			 unsigned int set_mask, unsigned int clear_mask)
+{
+	unsigned long size = pages * PAGE_SIZE;
+	struct page_change_data data;
+	int ret;
+
+	data.set_mask = set_mask;
+	data.clear_mask = clear_mask;
+
+	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
+				  &data);
+
+	flush_tlb_kernel_range(start, start + size);
+
+	return ret;
+}
+
+int set_memory_ro(unsigned long addr, int numpages)
+{
+	return change_memory(addr, numpages, 0, _PAGE_RW);
+}
+
+int set_memory_rw(unsigned long addr, int numpages)
+{
+	return change_memory(addr, numpages, _PAGE_RW, 0);
+}
+
+int set_memory_nx(unsigned long addr, int numpages)
+{
+	return -EOPNOTSUPP;
+}
+
+int set_memory_x(unsigned long addr, int numpages)
+{
+	return -EOPNOTSUPP;
+}

arch/um/kernel/um_arch.c

@@ -13,6 +13,7 @@
 #include <linux/sched.h>
 #include <linux/sched/task.h>
 #include <linux/kmsg_dump.h>
+#include <linux/suspend.h>
 
 #include <asm/processor.h>
 #include <asm/sections.h>
@@ -377,3 +378,69 @@ void *text_poke(void *addr, const void *opcode, size_t len)
 void text_poke_sync(void)
 {
 }
+
+void uml_pm_wake(void)
+{
+	pm_system_wakeup();
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int um_suspend_valid(suspend_state_t state)
+{
+	return state == PM_SUSPEND_MEM;
+}
+
+static int um_suspend_prepare(void)
+{
+	um_irqs_suspend();
+	return 0;
+}
+
+static int um_suspend_enter(suspend_state_t state)
+{
+	if (WARN_ON(state != PM_SUSPEND_MEM))
+		return -EINVAL;
+
+	/*
+	 * This is identical to the idle sleep, but we've just
+	 * (during suspend) turned off all interrupt sources
+	 * except for the ones we want, so now we can only wake
+	 * up on something we actually want to wake up on. All
+	 * timing has also been suspended.
+	 */
+	um_idle_sleep();
+	return 0;
+}
+
+static void um_suspend_finish(void)
+{
+	um_irqs_resume();
+}
+
+const struct platform_suspend_ops um_suspend_ops = {
+	.valid = um_suspend_valid,
+	.prepare = um_suspend_prepare,
+	.enter = um_suspend_enter,
+	.finish = um_suspend_finish,
+};
+
+static int init_pm_wake_signal(void)
+{
+	/*
+	 * In external time-travel mode we can't use signals to wake up
+	 * since that would mess with the scheduling. We'll have to do
+	 * some additional work to support wakeup on virtio devices or
+	 * similar, perhaps implementing a fake RTC controller that can
+	 * trigger wakeup (and request the appropriate scheduling from
+	 * the external scheduler when going to suspend.)
+	 */
+	if (time_travel_mode != TT_MODE_EXTERNAL)
+		register_pm_wake_signal();
+
+	suspend_set_ops(&um_suspend_ops);
+
+	return 0;
+}
+
+late_initcall(init_pm_wake_signal);
+#endif

arch/um/os-Linux/Makefile

@@ -10,6 +10,8 @@ obj-y = execvp.o file.o helper.o irq.o main.o mem.o process.o \
 	registers.o sigio.o signal.o start_up.o time.o tty.o \
 	umid.o user_syms.o util.o drivers/ skas/
 
+CFLAGS_signal.o += -Wframe-larger-than=4096
+
 obj-$(CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA) += elf_aux.o
 
 USER_OBJS := $(user-objs-y) elf_aux.o execvp.o file.o helper.o irq.o \

arch/um/os-Linux/helper.c

@@ -45,7 +45,7 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv)
 	unsigned long stack, sp;
 	int pid, fds[2], ret, n;
 
-	stack = alloc_stack(0, __cant_sleep());
+	stack = alloc_stack(__cant_sleep());
 	if (stack == 0)
 		return -ENOMEM;
 
@@ -116,7 +116,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
 	unsigned long stack, sp;
 	int pid, status, err;
 
-	stack = alloc_stack(0, __cant_sleep());
+	stack = alloc_stack(__cant_sleep());
 	if (stack == 0)
 		return -ENOMEM;
 

arch/um/os-Linux/irq.c

@@ -45,10 +45,10 @@ int os_epoll_triggered(int index, int events)
  * access to the right includes/defines for EPOLL constants.
  */
 
-int os_event_mask(int irq_type)
+int os_event_mask(enum um_irq_type irq_type)
 {
 	if (irq_type == IRQ_READ)
-		return EPOLLIN | EPOLLPRI;
+		return EPOLLIN | EPOLLPRI | EPOLLERR | EPOLLHUP | EPOLLRDHUP;
 	if (irq_type == IRQ_WRITE)
 		return EPOLLOUT;
 	return 0;

arch/um/os-Linux/sigio.c

@@ -164,45 +164,55 @@ static void update_thread(void)
 	set_signals_trace(flags);
 }
 
-int add_sigio_fd(int fd)
+int __add_sigio_fd(int fd)
 {
 	struct pollfd *p;
-	int err = 0, i, n;
+	int err, i, n;
 
-	sigio_lock();
 	for (i = 0; i < all_sigio_fds.used; i++) {
 		if (all_sigio_fds.poll[i].fd == fd)
 			break;
 	}
 	if (i == all_sigio_fds.used)
-		goto out;
+		return -ENOSPC;
 
 	p = &all_sigio_fds.poll[i];
 
 	for (i = 0; i < current_poll.used; i++) {
 		if (current_poll.poll[i].fd == fd)
-			goto out;
+			return 0;
 	}
 
 	n = current_poll.used;
 	err = need_poll(&next_poll, n + 1);
 	if (err)
-		goto out;
+		return err;
 
 	memcpy(next_poll.poll, current_poll.poll,
 	       current_poll.used * sizeof(struct pollfd));
 	next_poll.poll[n] = *p;
 	next_poll.used = n + 1;
 	update_thread();
- out:
+
+	return 0;
+}
+
+
+int add_sigio_fd(int fd)
+{
+	int err;
+
+	sigio_lock();
+	err = __add_sigio_fd(fd);
 	sigio_unlock();
+
 	return err;
 }
 
-int ignore_sigio_fd(int fd)
+int __ignore_sigio_fd(int fd)
 {
 	struct pollfd *p;
-	int err = 0, i, n = 0;
+	int err, i, n = 0;
 
 	/*
 	 * This is called from exitcalls elsewhere in UML - if
@@ -212,17 +222,16 @@ int ignore_sigio_fd(int fd)
 	if (write_sigio_pid == -1)
 		return -EIO;
 
-	sigio_lock();
 	for (i = 0; i < current_poll.used; i++) {
 		if (current_poll.poll[i].fd == fd)
 			break;
 	}
 	if (i == current_poll.used)
-		goto out;
+		return -ENOENT;
 
 	err = need_poll(&next_poll, current_poll.used - 1);
 	if (err)
-		goto out;
+		return err;
 
 	for (i = 0; i < current_poll.used; i++) {
 		p = &current_poll.poll[i];
@@ -232,8 +241,18 @@ int ignore_sigio_fd(int fd)
 	next_poll.used = current_poll.used - 1;
 
 	update_thread();
- out:
+
+	return 0;
+}
+
+int ignore_sigio_fd(int fd)
+{
+	int err;
+
+	sigio_lock();
+	err = __ignore_sigio_fd(fd);
 	sigio_unlock();
+
 	return err;
 }
 
@@ -336,7 +355,7 @@ static void write_sigio_workaround(void)
 	close(l_write_sigio_fds[1]);
 }
 
-void sigio_broken(int fd, int read)
+void sigio_broken(int fd)
 {
 	int err;
 
@@ -352,7 +371,7 @@ void sigio_broken(int fd, int read)
 
 	all_sigio_fds.poll[all_sigio_fds.used++] =
 		((struct pollfd) { .fd  	= fd,
-				   .events 	= read ? POLLIN : POLLOUT,
+				   .events 	= POLLIN,
 				   .revents 	= 0 });
 out:
 	sigio_unlock();
@@ -360,17 +379,16 @@ void sigio_broken(int fd, int read)
 
 /* Changed during early boot */
 static int pty_output_sigio;
-static int pty_close_sigio;
 
-void maybe_sigio_broken(int fd, int read)
+void maybe_sigio_broken(int fd)
 {
 	if (!isatty(fd))
 		return;
 
-	if ((read || pty_output_sigio) && (!read || pty_close_sigio))
+	if (pty_output_sigio)
 		return;
 
-	sigio_broken(fd, read);
+	sigio_broken(fd);
 }
 
 static void sigio_cleanup(void)
@@ -514,19 +532,6 @@ static void tty_output(int master, int slave)
 		printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n);
 }
 
-static void tty_close(int master, int slave)
-{
-	printk(UM_KERN_INFO "Checking that host ptys support SIGIO on "
-	       "close...");
-
-	close(slave);
-	if (got_sigio) {
-		printk(UM_KERN_CONT "Yes\n");
-		pty_close_sigio = 1;
-	} else
-		printk(UM_KERN_CONT "No, enabling workaround\n");
-}
-
 static void __init check_sigio(void)
 {
 	if ((access("/dev/ptmx", R_OK) < 0) &&
@@ -536,7 +541,6 @@ static void __init check_sigio(void)
 		return;
 	}
 	check_one_sigio(tty_output);
-	check_one_sigio(tty_close);
 }
 
 /* Here because it only does the SIGIO testing for now */

arch/um/os-Linux/signal.c

@@ -136,6 +136,16 @@ void set_sigstack(void *sig_stack, int size)
 		panic("enabling signal stack failed, errno = %d\n", errno);
 }
 
+static void sigusr1_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
+{
+	uml_pm_wake();
+}
+
+void register_pm_wake_signal(void)
+{
+	set_handler(SIGUSR1);
+}
+
 static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
 	[SIGSEGV] = sig_handler,
 	[SIGBUS] = sig_handler,
@@ -145,7 +155,9 @@ static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
 
 	[SIGIO] = sig_handler,
 	[SIGWINCH] = sig_handler,
-	[SIGALRM] = timer_alarm_handler
+	[SIGALRM] = timer_alarm_handler,
+
+	[SIGUSR1] = sigusr1_handler,
 };
 
 static void hard_handler(int sig, siginfo_t *si, void *p)
@@ -222,6 +234,11 @@ void set_handler(int sig)
 		panic("sigprocmask failed - errno = %d\n", errno);
 }
 
+void send_sigio_to_self(void)
+{
+	kill(os_getpid(), SIGIO);
+}
+
 int change_sig(int signal, int on)
 {
 	sigset_t sigset;
@@ -254,6 +271,9 @@ void unblock_signals(void)
 		return;
 
 	signals_enabled = 1;
+#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT
+	deliver_time_travel_irqs();
+#endif
 
 	/*
 	 * We loop because the IRQ handler returns with interrupts off.  So,

arch/um/os-Linux/skas/process.c

@@ -400,7 +400,20 @@ void userspace(struct uml_pt_regs *regs, unsigned long *aux_fp_regs)
 		if (WIFSTOPPED(status)) {
 			int sig = WSTOPSIG(status);
 
+			/* These signal handlers need the si argument.
+			 * The SIGIO and SIGALARM handlers which constitute the
+			 * majority of invocations, do not use it.
+			 */
+			switch (sig) {
+			case SIGSEGV:
+			case SIGTRAP:
+			case SIGILL:
+			case SIGBUS:
+			case SIGFPE:
+			case SIGWINCH:
 				ptrace(PTRACE_GETSIGINFO, pid, 0, (struct siginfo *)&si);
+				break;
+			}
 
 			switch (sig) {
 			case SIGSEGV:

arch/um/os-Linux/time.c

@@ -7,6 +7,7 @@
  */
 
 #include <stddef.h>
+#include <unistd.h>
 #include <errno.h>
 #include <signal.h>
 #include <time.h>
@@ -99,19 +100,9 @@ long long os_nsecs(void)
 }
 
 /**
- * os_idle_sleep() - sleep for a given time of nsecs
- * @nsecs: nanoseconds to sleep
+ * os_idle_sleep() - sleep until interrupted
  */
-void os_idle_sleep(unsigned long long nsecs)
+void os_idle_sleep(void)
 {
-	struct timespec ts = {
-		.tv_sec  = nsecs / UM_NSEC_PER_SEC,
-		.tv_nsec = nsecs % UM_NSEC_PER_SEC
-	};
-
-	/*
-	 * Relay the signal if clock_nanosleep is interrupted.
-	 */
-	if (clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL))
-		deliver_alarm();
+	pause();
 }

arch/um/os-Linux/umid.c

@@ -137,20 +137,13 @@ static inline int is_umdir_used(char *dir)
 {
 	char pid[sizeof("nnnnnnnnn")], *end, *file;
 	int dead, fd, p, n, err;
-	size_t filelen;
+	size_t filelen = strlen(dir) + sizeof("/pid") + 1;
 
-	err = asprintf(&file, "%s/pid", dir);
-	if (err < 0)
-		return 0;
-
-	filelen = strlen(file);
+	file = malloc(filelen);
+	if (!file)
+		return -ENOMEM;
 
-	n = snprintf(file, filelen, "%s/pid", dir);
-	if (n >= filelen) {
-		printk(UM_KERN_ERR "is_umdir_used - pid filename too long\n");
-		err = -E2BIG;
-		goto out;
-	}
+	snprintf(file, filelen, "%s/pid", dir);
 
 	dead = 0;
 	fd = open(file, O_RDONLY);

drivers/char/hw_random/Kconfig

@@ -528,15 +528,15 @@ endif # HW_RANDOM
 
 config UML_RANDOM
 	depends on UML
-	tristate "Hardware random number generator"
+	select HW_RANDOM
+	tristate "UML Random Number Generator support"
 	help
 	  This option enables UML's "hardware" random number generator.  It
 	  attaches itself to the host's /dev/random, supplying as much entropy
 	  as the host has, rather than the small amount the UML gets from its
-	  own drivers.  It registers itself as a standard hardware random number
-	  generator, major 10, minor 183, and the canonical device name is
-	  /dev/hwrng.
-	  The way to make use of this is to install the rng-tools package
-	  (check your distro, or download from
-	  http://sourceforge.net/projects/gkernel/).  rngd periodically reads
-	  /dev/hwrng and injects the entropy into /dev/random.
+	  own drivers. It registers itself as a rng-core driver thus providing
+	  a device which is usually called /dev/hwrng. This hardware random
+	  number generator does feed into the kernel's random number generator
+	  entropy pool.
+
+	  If unsure, say Y.