Merge branch 'for-linus-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

Pull UML updates from Richard Weinberger:

 - a new hrtimer based clocksource by Anton Ivanov

 - ptrace() enhancments by Richard Weinberger

 - random cleanups and bug fixes all over the place

* 'for-linus-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: Switch clocksource to hrtimers
  um: net: replace GFP_KERNEL with GFP_ATOMIC when spinlock is held
  um: Report host OOM more nicely
  um: Simplify STUB_DATA loading
  um: Remove dead symbol from i386 syscall stub
  um: Remove dead code from x86_64 syscall stub
  um: Get rid of open coded NR_SYSCALLS
  um: Store syscall number after syscall_trace_enter()
  um: Define PTRACE_OLDSETOPTIONS

20 files changed, 296 insertions, 269 deletions

diff --git a/arch/um/Makefile b/arch/um/Makefile
index e3abe6f..25ed409 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -131,7 +131,7 @@ export LDS_ELF_FORMAT := $(ELF_FORMAT)
 # The wrappers will select whether using "malloc" or the kernel allocator.
 LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc
 
-LD_FLAGS_CMDLINE = $(foreach opt,$(LDFLAGS),-Wl,$(opt))
+LD_FLAGS_CMDLINE = $(foreach opt,$(LDFLAGS),-Wl,$(opt)) -lrt
 
 # Used by link-vmlinux.sh which has special support for um link
 export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE)
diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index f70dd54..9ef669d 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -388,7 +388,7 @@ static const struct net_device_ops uml_netdev_ops = {
 static int driver_registered;
 
 static void eth_configure(int n, void *init, char *mac,
-			  struct transport *transport)
+			  struct transport *transport, gfp_t gfp_mask)
 {
 	struct uml_net *device;
 	struct net_device *dev;
@@ -397,7 +397,7 @@ static void eth_configure(int n, void *init, char *mac,
 
 	size = transport->private_size + sizeof(struct uml_net_private);
 
-	device = kzalloc(sizeof(*device), GFP_KERNEL);
+	device = kzalloc(sizeof(*device), gfp_mask);
 	if (device == NULL) {
 		printk(KERN_ERR "eth_configure failed to allocate struct "
 		       "uml_net\n");
@@ -568,7 +568,7 @@ static LIST_HEAD(transports);
 static LIST_HEAD(eth_cmd_line);
 
 static int check_transport(struct transport *transport, char *eth, int n,
-			   void **init_out, char **mac_out)
+			   void **init_out, char **mac_out, gfp_t gfp_mask)
 {
 	int len;
 
@@ -582,7 +582,7 @@ static int check_transport(struct transport *transport, char *eth, int n,
 	else if (*eth != '\0')
 		return 0;
 
-	*init_out = kmalloc(transport->setup_size, GFP_KERNEL);
+	*init_out = kmalloc(transport->setup_size, gfp_mask);
 	if (*init_out == NULL)
 		return 1;
 
@@ -609,11 +609,11 @@ void register_transport(struct transport *new)
 	list_for_each_safe(ele, next, &eth_cmd_line) {
 		eth = list_entry(ele, struct eth_init, list);
 		match = check_transport(new, eth->init, eth->index, &init,
-					&mac);
+					&mac, GFP_KERNEL);
 		if (!match)
 			continue;
 		else if (init != NULL) {
-			eth_configure(eth->index, init, mac, new);
+			eth_configure(eth->index, init, mac, new, GFP_KERNEL);
 			kfree(init);
 		}
 		list_del(&eth->list);
@@ -631,10 +631,11 @@ static int eth_setup_common(char *str, int index)
 	spin_lock(&transports_lock);
 	list_for_each(ele, &transports) {
 		transport = list_entry(ele, struct transport, list);
-	        if (!check_transport(transport, str, index, &init, &mac))
+	        if (!check_transport(transport, str, index, &init,
+					&mac, GFP_ATOMIC))
 			continue;
 		if (init != NULL) {
-			eth_configure(index, init, mac, transport);
+			eth_configure(index, init, mac, transport, GFP_ATOMIC);
 			kfree(init);
 		}
 		found = 1;
diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h
index 2966adb..5ab2062 100644
--- a/arch/um/include/asm/ptrace-generic.h
+++ b/arch/um/include/asm/ptrace-generic.h
@@ -27,6 +27,8 @@ struct pt_regs {
 
 #define instruction_pointer(regs) PT_REGS_IP(regs)
 
+#define PTRACE_OLDSETOPTIONS 21
+
 struct task_struct;
 
 extern long subarch_ptrace(struct task_struct *child, long request,
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index ad3fa3a..868e6c3 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -1,4 +1,6 @@
 /*
+ * 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
  */
@@ -183,6 +185,7 @@ extern int create_mem_file(unsigned long long len);
 /* process.c */
 extern unsigned long os_process_pc(int pid);
 extern int os_process_parent(int pid);
+extern void os_alarm_process(int pid);
 extern void os_stop_process(int pid);
 extern void os_kill_process(int pid, int reap_child);
 extern void os_kill_ptraced_process(int pid, int reap_child);
@@ -217,7 +220,7 @@ extern int set_umid(char *name);
 extern char *get_umid(void);
 
 /* signal.c */
-extern void timer_init(void);
+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);
@@ -227,6 +230,7 @@ extern void unblock_signals(void);
 extern int get_signals(void);
 extern int set_signals(int enable);
 extern int os_is_signal_stack(void);
+extern void deliver_alarm(void);
 
 /* util.c */
 extern void stack_protections(unsigned long address);
@@ -238,12 +242,16 @@ extern void um_early_printk(const char *s, unsigned int n);
 extern void os_fix_helper_signals(void);
 
 /* time.c */
-extern void idle_sleep(unsigned long long nsecs);
-extern int set_interval(void);
-extern int timer_one_shot(int ticks);
-extern long long disable_timer(void);
+extern void os_idle_sleep(unsigned long long nsecs);
+extern int os_timer_create(void* timer);
+extern int os_timer_set_interval(void* timer, void* its);
+extern int os_timer_one_shot(int ticks);
+extern long long os_timer_disable(void);
+extern long os_timer_remain(void* timer);
 extern void uml_idle_timer(void);
+extern long long os_persistent_clock_emulation(void);
 extern long long os_nsecs(void);
+extern long long os_vnsecs(void);
 
 /* skas/mem.c */
 extern long run_syscall_stub(struct mm_id * mm_idp,
@@ -274,6 +282,7 @@ extern void initial_thread_cb_skas(void (*proc)(void *),
 				 void *arg);
 extern void halt_skas(void);
 extern void reboot_skas(void);
+extern int get_syscall(struct uml_pt_regs *regs);
 
 /* irq.c */
 extern int os_waiting_for_events(struct irq_fd *active_fds);
diff --git a/arch/um/include/shared/skas/stub-data.h b/arch/um/include/shared/skas/stub-data.h
index f6ed92c..a9deece 100644
--- a/arch/um/include/shared/skas/stub-data.h
+++ b/arch/um/include/shared/skas/stub-data.h
@@ -1,4 +1,6 @@
 /*
+
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2005 Jeff Dike (jdike@karaya.com)
  * Licensed under the GPL
  */
@@ -6,12 +8,11 @@
 #ifndef __STUB_DATA_H
 #define __STUB_DATA_H
 
-#include <sys/time.h>
+#include <time.h>
 
 struct stub_data {
-	long offset;
+	unsigned long offset;
 	int fd;
-	struct itimerval timer;
 	long err;
 };
 
diff --git a/arch/um/include/shared/timer-internal.h b/arch/um/include/shared/timer-internal.h
new file mode 100644
index 0000000..03e6f21
--- /dev/null
+++ b/arch/um/include/shared/timer-internal.h
@@ -0,0 +1,13 @@
+/*
+ * 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__
+#define __TIMER_INTERNAL_H__
+
+#define TIMER_MULTIPLIER 256
+#define TIMER_MIN_DELTA  500
+
+#endif
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index a6d9226..48af59a 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -1,4 +1,6 @@
 /*
+ * 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
@@ -27,6 +29,7 @@
 #include <kern_util.h>
 #include <os.h>
 #include <skas.h>
+#include <timer-internal.h>
 
 /*
  * This is a per-cpu array.  A processor only modifies its entry and it only
@@ -203,11 +206,8 @@ void initial_thread_cb(void (*proc)(void *), void *arg)
 
 void arch_cpu_idle(void)
 {
-	unsigned long long nsecs;
-
 	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
-	nsecs = disable_timer();
-	idle_sleep(nsecs);
+	os_idle_sleep(UM_NSEC_PER_SEC);
 	local_irq_enable();
 }
 
diff --git a/arch/um/kernel/skas/clone.c b/arch/um/kernel/skas/clone.c
index 289771d..0f25d41 100644
--- a/arch/um/kernel/skas/clone.c
+++ b/arch/um/kernel/skas/clone.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
@@ -35,11 +36,6 @@ stub_clone_handler(void)
 	if (err)
 		goto out;
 
-	err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
-			    (long) &data->timer, 0);
-	if (err)
-		goto out;
-
 	remap_stack(data->fd, data->offset);
 	goto done;
 
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index fda1deb..9591a66 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
@@ -61,10 +62,12 @@ 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();
 	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();
 
 	if (to_mm->id.u.pid < 0) {
 		ret = to_mm->id.u.pid;
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index d9ec006..1683b8e 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -8,9 +8,7 @@
 #include <kern_util.h>
 #include <sysdep/ptrace.h>
 #include <sysdep/syscalls.h>
-
-extern int syscall_table_size;
-#define NR_SYSCALLS (syscall_table_size / sizeof(void *))
+#include <os.h>
 
 void handle_syscall(struct uml_pt_regs *r)
 {
@@ -23,19 +21,12 @@ void handle_syscall(struct uml_pt_regs *r)
 		goto out;
 	}
 
-	/*
-	 * This should go in the declaration of syscall, but when I do that,
-	 * strace -f -c bash -c 'ls ; ls' breaks, sometimes not tracing
-	 * children at all, sometimes hanging when bash doesn't see the first
-	 * ls exit.
-	 * The assembly looks functionally the same to me.  This is
-	 *     gcc version 4.0.1 20050727 (Red Hat 4.0.1-5)
-	 * in case it's a compiler bug.
-	 */
-	syscall = UPT_SYSCALL_NR(r);
-	if ((syscall >= NR_SYSCALLS) || (syscall < 0))
+	syscall = get_syscall(r);
+
+	if ((syscall > __NR_syscall_max) || syscall < 0)
 		result = -ENOSYS;
-	else result = EXECUTE_SYSCALL(syscall, regs);
+	else
+		result = EXECUTE_SYSCALL(syscall, regs);
 
 out:
 	PT_REGS_SET_SYSCALL_RETURN(regs, result);
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index 5af441e..25c2366 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -1,4 +1,7 @@
 /*
+ * 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
  */
@@ -7,11 +10,15 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/jiffies.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
 #include <linux/threads.h>
 #include <asm/irq.h>
 #include <asm/param.h>
 #include <kern_util.h>
 #include <os.h>
+#include <timer-internal.h>
 
 void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 {
@@ -24,81 +31,97 @@ void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 
 static int itimer_shutdown(struct clock_event_device *evt)
 {
-	disable_timer();
+	os_timer_disable();
 	return 0;
 }
 
 static int itimer_set_periodic(struct clock_event_device *evt)
 {
-	set_interval();
+	os_timer_set_interval(NULL, NULL);
 	return 0;
 }
 
 static int itimer_next_event(unsigned long delta,
 			     struct clock_event_device *evt)
 {
-	return timer_one_shot(delta + 1);
+	return os_timer_one_shot(delta);
 }
 
-static struct clock_event_device itimer_clockevent = {
-	.name			= "itimer",
+static int itimer_one_shot(struct clock_event_device *evt)
+{
+	os_timer_one_shot(1);
+	return 0;
+}
+
+static struct clock_event_device timer_clockevent = {
+	.name			= "posix-timer",
 	.rating			= 250,
 	.cpumask		= cpu_all_mask,
 	.features		= CLOCK_EVT_FEAT_PERIODIC |
 				  CLOCK_EVT_FEAT_ONESHOT,
 	.set_state_shutdown	= itimer_shutdown,
 	.set_state_periodic	= itimer_set_periodic,
-	.set_state_oneshot	= itimer_shutdown,
+	.set_state_oneshot	= itimer_one_shot,
 	.set_next_event		= itimer_next_event,
-	.shift			= 32,
+	.shift			= 0,
+	.max_delta_ns		= 0xffffffff,
+	.min_delta_ns		= TIMER_MIN_DELTA, //microsecond resolution should be enough for anyone, same as 640K RAM
 	.irq			= 0,
+	.mult			= 1,
 };
 
 static irqreturn_t um_timer(int irq, void *dev)
 {
-	(*itimer_clockevent.event_handler)(&itimer_clockevent);
+	if (get_current()->mm != NULL)
+	{
+        /* userspace - relay signal, results in correct userspace timers */
+		os_alarm_process(get_current()->mm->context.id.u.pid);
+	}
+
+	(*timer_clockevent.event_handler)(&timer_clockevent);
 
 	return IRQ_HANDLED;
 }
 
-static cycle_t itimer_read(struct clocksource *cs)
+static cycle_t timer_read(struct clocksource *cs)
 {
-	return os_nsecs() / 1000;
+	return os_nsecs() / TIMER_MULTIPLIER;
 }
 
-static struct clocksource itimer_clocksource = {
-	.name		= "itimer",
+static struct clocksource timer_clocksource = {
+	.name		= "timer",
 	.rating		= 300,
-	.read		= itimer_read,
+	.read		= timer_read,
 	.mask		= CLOCKSOURCE_MASK(64),
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
-static void __init setup_itimer(void)
+static void __init timer_setup(void)
 {
 	int err;
 
-	err = request_irq(TIMER_IRQ, um_timer, 0, "timer", NULL);
+	err = request_irq(TIMER_IRQ, um_timer, IRQF_TIMER, "hr timer", NULL);
 	if (err != 0)
 		printk(KERN_ERR "register_timer : request_irq failed - "
 		       "errno = %d\n", -err);
 
-	itimer_clockevent.mult = div_sc(HZ, NSEC_PER_SEC, 32);
-	itimer_clockevent.max_delta_ns =
-		clockevent_delta2ns(60 * HZ, &itimer_clockevent);
-	itimer_clockevent.min_delta_ns =
-		clockevent_delta2ns(1, &itimer_clockevent);
-	err = clocksource_register_hz(&itimer_clocksource, USEC_PER_SEC);
+	err = os_timer_create(NULL);
+	if (err != 0) {
+		printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
+		return;
+	}
+
+	err = clocksource_register_hz(&timer_clocksource, NSEC_PER_SEC/TIMER_MULTIPLIER);
 	if (err) {
 		printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
 		return;
 	}
-	clockevents_register_device(&itimer_clockevent);
+	clockevents_register_device(&timer_clockevent);
 }
 
 void read_persistent_clock(struct timespec *ts)
 {
-	long long nsecs = os_nsecs();
+	long long nsecs = os_persistent_clock_emulation();
 
 	set_normalized_timespec(ts, nsecs / NSEC_PER_SEC,
 				nsecs % NSEC_PER_SEC);
@@ -106,6 +129,6 @@ void read_persistent_clock(struct timespec *ts)
 
 void __init time_init(void)
 {
-	timer_init();
-	late_time_init = setup_itimer;
+	timer_set_signal_handler();
+	late_time_init = timer_setup;
 }
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 2077248..3777b82 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -50,6 +50,13 @@ struct host_vm_change {
 	   .index	= 0, \
 	   .force	= force })
 
+static void report_enomem(void)
+{
+	printk(KERN_ERR "UML ran out of memory on the host side! "
+			"This can happen due to a memory limitation or "
+			"vm.max_map_count has been reached.\n");
+}
+
 static int do_ops(struct host_vm_change *hvc, int end,
 		  int finished)
 {
@@ -81,6 +88,9 @@ static int do_ops(struct host_vm_change *hvc, int end,
 		}
 	}
 
+	if (ret == -ENOMEM)
+		report_enomem();
+
 	return ret;
 }
 
@@ -433,8 +443,12 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
 	else if (pte_newprot(*pte))
 		err = protect(mm_id, address, PAGE_SIZE, prot, 1, &flush);
 
-	if (err)
+	if (err) {
+		if (err == -ENOMEM)
+			report_enomem();
+
 		goto kill;
+	}
 
 	*pte = pte_mkuptodate(*pte);
 
diff --git a/arch/um/os-Linux/internal.h b/arch/um/os-Linux/internal.h
deleted file mode 100644
index 0dc2c9f..0000000
--- a/arch/um/os-Linux/internal.h
+++ /dev/null
@@ -1 +0,0 @@
-void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc);
diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
index df9191a..9d499de 100644
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
@@ -163,13 +164,13 @@ int __init main(int argc, char **argv, char **envp)
 
 	/*
 	 * This signal stuff used to be in the reboot case.  However,
-	 * sometimes a SIGVTALRM can come in when we're halting (reproducably
+	 * sometimes a timer signal can come in when we're halting (reproducably
 	 * when writing out gcov information, presumably because that takes
 	 * some time) and cause a segfault.
 	 */
 
-	/* stop timers and set SIGVTALRM to be ignored */
-	disable_timer();
+	/* stop timers and set timer signal to be ignored */
+	os_timer_disable();
 
 	/* disable SIGIO for the fds and set SIGIO to be ignored */
 	err = deactivate_all_fds();
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index 8408aba..b3e0d40 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
@@ -89,6 +90,11 @@ int os_process_parent(int pid)
 	return parent;
 }
 
+void os_alarm_process(int pid)
+{
+	kill(pid, SIGALRM);
+}
+
 void os_stop_process(int pid)
 {
 	kill(pid, SIGSTOP);
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 036d0db..c211153 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -1,4 +1,6 @@
 /*
+ * 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
@@ -13,7 +15,6 @@
 #include <kern_util.h>
 #include <os.h>
 #include <sysdep/mcontext.h>
-#include "internal.h"
 
 void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = {
 	[SIGTRAP]	= relay_signal,
@@ -23,7 +24,8 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = {
 	[SIGBUS]	= bus_handler,
 	[SIGSEGV]	= segv_handler,
 	[SIGIO]		= sigio_handler,
-	[SIGVTALRM]	= timer_handler };
+	[SIGALRM]	= timer_handler
+};
 
 static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
 {
@@ -38,7 +40,7 @@ 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 != SIGVTALRM))
+	if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGALRM))
 		unblock_signals();
 
 	(*sig_info[sig])(sig, si, &r);
@@ -55,8 +57,8 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
 #define SIGIO_BIT 0
 #define SIGIO_MASK (1 << SIGIO_BIT)
 
-#define SIGVTALRM_BIT 1
-#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
+#define SIGALRM_BIT 1
+#define SIGALRM_MASK (1 << SIGALRM_BIT)
 
 static int signals_enabled;
 static unsigned int signals_pending;
@@ -78,36 +80,38 @@ void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
 	set_signals(enabled);
 }
 
-static void real_alarm_handler(mcontext_t *mc)
+static void timer_real_alarm_handler(mcontext_t *mc)
 {
 	struct uml_pt_regs regs;
 
 	if (mc != NULL)
 		get_regs_from_mc(&regs, mc);
-	regs.is_user = 0;
-	unblock_signals();
-	timer_handler(SIGVTALRM, NULL, &regs);
+	timer_handler(SIGALRM, NULL, &regs);
 }
 
-void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
+void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
 {
 	int enabled;
 
 	enabled = signals_enabled;
 	if (!signals_enabled) {
-		signals_pending |= SIGVTALRM_MASK;
+		signals_pending |= SIGALRM_MASK;
 		return;
 	}
 
 	block_signals();
 
-	real_alarm_handler(mc);
+	timer_real_alarm_handler(mc);
 	set_signals(enabled);
 }
 
-void timer_init(void)
+void deliver_alarm(void) {
+    timer_alarm_handler(SIGALRM, NULL, NULL);
+}
+
+void timer_set_signal_handler(void)
 {
-	set_handler(SIGVTALRM);
+	set_handler(SIGALRM);
 }
 
 void set_sigstack(void *sig_stack, int size)
@@ -131,10 +135,9 @@ static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = {
 
 	[SIGIO] = sig_handler,
 	[SIGWINCH] = sig_handler,
-	[SIGVTALRM] = alarm_handler
+	[SIGALRM] = timer_alarm_handler
 };
 
-
 static void hard_handler(int sig, siginfo_t *si, void *p)
 {
 	struct ucontext *uc = p;
@@ -188,9 +191,9 @@ void set_handler(int sig)
 
 	/* block irq ones */
 	sigemptyset(&action.sa_mask);
-	sigaddset(&action.sa_mask, SIGVTALRM);
 	sigaddset(&action.sa_mask, SIGIO);
 	sigaddset(&action.sa_mask, SIGWINCH);
+	sigaddset(&action.sa_mask, SIGALRM);
 
 	if (sig == SIGSEGV)
 		flags |= SA_NODEFER;
@@ -283,8 +286,8 @@ void unblock_signals(void)
 		if (save_pending & SIGIO_MASK)
 			sig_handler_common(SIGIO, NULL, NULL);
 
-		if (save_pending & SIGVTALRM_MASK)
-			real_alarm_handler(NULL);
+		if (save_pending & SIGALRM_MASK)
+			timer_real_alarm_handler(NULL);
 	}
 }
 
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 3dddedb..b856c66 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
@@ -45,7 +46,7 @@ static int ptrace_dump_regs(int pid)
  * Signals that are OK to receive in the stub - we'll just continue it.
  * SIGWINCH will happen when UML is inside a detached screen.
  */
-#define STUB_SIG_MASK ((1 << SIGVTALRM) | (1 << SIGWINCH))
+#define STUB_SIG_MASK ((1 << SIGALRM) | (1 << SIGWINCH))
 
 /* Signals that the stub will finish with - anything else is an error */
 #define STUB_DONE_MASK (1 << SIGTRAP)
@@ -137,9 +138,6 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
 	if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
 		fatal_sigsegv();
 
-	/* Mark this as a syscall */
-	UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
-
 	if (!local_using_sysemu)
 	{
 		err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
@@ -174,24 +172,25 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
 	handle_syscall(regs);
 }
 
+int get_syscall(struct uml_pt_regs *regs)
+{
+	UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
+
+	return UPT_SYSCALL_NR(regs);
+}
+
 extern char __syscall_stub_start[];
 
 static int userspace_tramp(void *stack)
 {
 	void *addr;
-	int err, fd;
+	int fd;
 	unsigned long long offset;
 
 	ptrace(PTRACE_TRACEME, 0, 0, 0);
 
 	signal(SIGTERM, SIG_DFL);
 	signal(SIGWINCH, SIG_IGN);
-	err = set_interval();
-	if (err) {
-		printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
-		       "errno = %d\n", err);
-		exit(1);
-	}
 
 	/*
 	 * This has a pte, but it can't be mapped in with the usual
@@ -282,7 +281,7 @@ int start_userspace(unsigned long stub_stack)
 			       "errno = %d\n", errno);
 			goto out_kill;
 		}
-	} while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
+	} while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGALRM));
 
 	if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
 		err = -EINVAL;
@@ -315,8 +314,6 @@ int start_userspace(unsigned long stub_stack)
 
 void userspace(struct uml_pt_regs *regs)
 {
-	struct itimerval timer;
-	unsigned long long nsecs, now;
 	int err, status, op, pid = userspace_pid[0];
 	/* To prevent races if using_sysemu changes under us.*/
 	int local_using_sysemu;
@@ -325,13 +322,8 @@ void userspace(struct uml_pt_regs *regs)
 	/* Handle any immediate reschedules or signals */
 	interrupt_end();
 
-	if (getitimer(ITIMER_VIRTUAL, &timer))
-		printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno);
-	nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
-		timer.it_value.tv_usec * UM_NSEC_PER_USEC;
-	nsecs += os_nsecs();
-
 	while (1) {
+
 		/*
 		 * This can legitimately fail if the process loads a
 		 * bogus value into a segment register.  It will
@@ -401,18 +393,7 @@ void userspace(struct uml_pt_regs *regs)
 			case SIGTRAP:
 				relay_signal(SIGTRAP, (struct siginfo *)&si, regs);
 				break;
-			case SIGVTALRM:
-				now = os_nsecs();
-				if (now < nsecs)
-					break;
-				block_signals();
-				(*sig_info[sig])(sig, (struct siginfo *)&si, regs);
-				unblock_signals();
-				nsecs = timer.it_value.tv_sec *
-					UM_NSEC_PER_SEC +
-					timer.it_value.tv_usec *
-					UM_NSEC_PER_USEC;
-				nsecs += os_nsecs();
+			case SIGALRM:
 				break;
 			case SIGIO:
 			case SIGILL:
@@ -460,7 +441,6 @@ __initcall(init_thread_regs);
 
 int copy_context_skas0(unsigned long new_stack, int pid)
 {
-	struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
 	int err;
 	unsigned long current_stack = current_stub_stack();
 	struct stub_data *data = (struct stub_data *) current_stack;
@@ -472,11 +452,10 @@ int copy_context_skas0(unsigned long new_stack, int pid)
 	 * prepare offset and fd of child's stack as argument for parent's
 	 * and child's mmap2 calls
 	 */
-	*data = ((struct stub_data) { .offset	= MMAP_OFFSET(new_offset),
-				      .fd	= new_fd,
-				      .timer    = ((struct itimerval)
-					           { .it_value = tv,
-						     .it_interval = tv }) });
+	*data = ((struct stub_data) {
+			.offset	= MMAP_OFFSET(new_offset),
+			.fd     = new_fd
+	});
 
 	err = ptrace_setregs(pid, thread_regs);
 	if (err < 0) {
diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
index e9824d5..0e39b99 100644
--- a/arch/um/os-Linux/time.c
+++ b/arch/um/os-Linux/time.c
@@ -1,4 +1,7 @@
 /*
+ * 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
  */
@@ -10,177 +13,177 @@
 #include <sys/time.h>
 #include <kern_util.h>
 #include <os.h>
-#include "internal.h"
+#include <string.h>
+#include <timer-internal.h>
 
-int set_interval(void)
-{
-	int usec = UM_USEC_PER_SEC / UM_HZ;
-	struct itimerval interval = ((struct itimerval) { { 0, usec },
-							  { 0, usec } });
-
-	if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
-		return -errno;
+static timer_t event_high_res_timer = 0;
 
-	return 0;
+static inline long long timeval_to_ns(const struct timeval *tv)
+{
+	return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) +
+		tv->tv_usec * UM_NSEC_PER_USEC;
 }
 
-int timer_one_shot(int ticks)
+static inline long long timespec_to_ns(const struct timespec *ts)
 {
-	unsigned long usec = ticks * UM_USEC_PER_SEC / UM_HZ;
-	unsigned long sec = usec / UM_USEC_PER_SEC;
-	struct itimerval interval;
-
-	usec %= UM_USEC_PER_SEC;
-	interval = ((struct itimerval) { { 0, 0 }, { sec, usec } });
+	return ((long long) ts->tv_sec * UM_NSEC_PER_SEC) +
+		ts->tv_nsec;
+}
 
-	if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
-		return -errno;
+long long os_persistent_clock_emulation (void) {
+	struct timespec realtime_tp;
 
-	return 0;
+	clock_gettime(CLOCK_REALTIME, &realtime_tp);
+	return timespec_to_ns(&realtime_tp);
 }
 
 /**
- * timeval_to_ns - Convert timeval to nanoseconds
- * @ts:		pointer to the timeval variable to be converted
- *
- * Returns the scalar nanosecond representation of the timeval
- * parameter.
- *
- * Ripped from linux/time.h because it's a kernel header, and thus
- * unusable from here.
+ * os_timer_create() - create an new posix (interval) timer
  */
-static inline long long timeval_to_ns(const struct timeval *tv)
-{
-	return ((long long) tv->tv_sec * UM_NSEC_PER_SEC) +
-		tv->tv_usec * UM_NSEC_PER_USEC;
+int os_timer_create(void* timer) {
+
+	timer_t* t = timer;
+
+	if(t == NULL) {
+		t = &event_high_res_timer;
+	}
+
+	if (timer_create(
+		CLOCK_MONOTONIC,
+		NULL,
+		t) == -1) {
+		return -1;
+	}
+	return 0;
 }
 
-long long disable_timer(void)
+int os_timer_set_interval(void* timer, void* i)
 {
-	struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } });
-	long long remain, max = UM_NSEC_PER_SEC / UM_HZ;
+	struct itimerspec its;
+	unsigned long long nsec;
+	timer_t* t = timer;
+	struct itimerspec* its_in = i;
 
-	if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0)
-		printk(UM_KERN_ERR "disable_timer - setitimer failed, "
-		       "errno = %d\n", errno);
+	if(t == NULL) {
+		t = &event_high_res_timer;
+	}
 
-	remain = timeval_to_ns(&time.it_value);
-	if (remain > max)
-		remain = max;
+	nsec = UM_NSEC_PER_SEC / UM_HZ;
 
-	return remain;
-}
+	if(its_in != NULL) {
+		its.it_value.tv_sec = its_in->it_value.tv_sec;
+		its.it_value.tv_nsec = its_in->it_value.tv_nsec;
+	} else {
+		its.it_value.tv_sec = 0;
+		its.it_value.tv_nsec = nsec;
+	}
 
-long long os_nsecs(void)
-{
-	struct timeval tv;
+	its.it_interval.tv_sec = 0;
+	its.it_interval.tv_nsec = nsec;
 
-	gettimeofday(&tv, NULL);
-	return timeval_to_ns(&tv);
-}
+	if(timer_settime(*t, 0, &its, NULL) == -1) {
+		return -errno;
+	}
 
-#ifdef UML_CONFIG_NO_HZ_COMMON
-static int after_sleep_interval(struct timespec *ts)
-{
 	return 0;
 }
 
-static void deliver_alarm(void)
+/**
+ * os_timer_remain() - returns the remaining nano seconds of the given interval
+ *                     timer
+ * Because this is the remaining time of an interval timer, which correspondends
+ * to HZ, this value can never be bigger than one second. Just
+ * the nanosecond part of the timer is returned.
+ * The returned time is relative to the start time of the interval timer.
+ * Return an negative value in an error case.
+ */
+long os_timer_remain(void* timer)
 {
-	alarm_handler(SIGVTALRM, NULL, NULL);
-}
+	struct itimerspec its;
+	timer_t* t = timer;
 
-static unsigned long long sleep_time(unsigned long long nsecs)
-{
-	return nsecs;
-}
+	if(t == NULL) {
+		t = &event_high_res_timer;
+	}
 
-#else
-unsigned long long last_tick;
-unsigned long long skew;
+	if(timer_gettime(t, &its) == -1) {
+		return -errno;
+	}
 
-static void deliver_alarm(void)
-{
-	unsigned long long this_tick = os_nsecs();
-	int one_tick = UM_NSEC_PER_SEC / UM_HZ;
+	return its.it_value.tv_nsec;
+}
 
-	/* Protection against the host's time going backwards */
-	if ((last_tick != 0) && (this_tick < last_tick))
-		this_tick = last_tick;
+int os_timer_one_shot(int ticks)
+{
+	struct itimerspec its;
+	unsigned long long nsec;
+	unsigned long sec;
 
-	if (last_tick == 0)
-		last_tick = this_tick - one_tick;
+    nsec = (ticks + 1);
+    sec = nsec / UM_NSEC_PER_SEC;
+	nsec = nsec % UM_NSEC_PER_SEC;
 
-	skew += this_tick - last_tick;
+	its.it_value.tv_sec = nsec / UM_NSEC_PER_SEC;
+	its.it_value.tv_nsec = nsec;
 
-	while (skew >= one_tick) {
-		alarm_handler(SIGVTALRM, NULL, NULL);
-		skew -= one_tick;
-	}
+	its.it_interval.tv_sec = 0;
+	its.it_interval.tv_nsec = 0; // we cheat here
 
-	last_tick = this_tick;
+	timer_settime(event_high_res_timer, 0, &its, NULL);
+	return 0;
 }
 
-static unsigned long long sleep_time(unsigned long long nsecs)
+/**
+ * os_timer_disable() - disable the posix (interval) timer
+ * Returns the remaining interval timer time in nanoseconds
+ */
+long long os_timer_disable(void)
 {
-	return nsecs > skew ? nsecs - skew : 0;
-}
+	struct itimerspec its;
 
-static inline long long timespec_to_us(const struct timespec *ts)
-{
-	return ((long long) ts->tv_sec * UM_USEC_PER_SEC) +
-		ts->tv_nsec / UM_NSEC_PER_USEC;
+	memset(&its, 0, sizeof(struct itimerspec));
+	timer_settime(event_high_res_timer, 0, &its, &its);
+
+	return its.it_value.tv_sec * UM_NSEC_PER_SEC + its.it_value.tv_nsec;
 }
 
-static int after_sleep_interval(struct timespec *ts)
+long long os_vnsecs(void)
 {
-	int usec = UM_USEC_PER_SEC / UM_HZ;
-	long long start_usecs = timespec_to_us(ts);
-	struct timeval tv;
-	struct itimerval interval;
-
-	/*
-	 * It seems that rounding can increase the value returned from
-	 * setitimer to larger than the one passed in.  Over time,
-	 * this will cause the remaining time to be greater than the
-	 * tick interval.  If this happens, then just reduce the first
-	 * tick to the interval value.
-	 */
-	if (start_usecs > usec)
-		start_usecs = usec;
-
-	start_usecs -= skew / UM_NSEC_PER_USEC;
-	if (start_usecs < 0)
-		start_usecs = 0;
+	struct timespec ts;
 
-	tv = ((struct timeval) { .tv_sec  = start_usecs / UM_USEC_PER_SEC,
-				 .tv_usec = start_usecs % UM_USEC_PER_SEC });
-	interval = ((struct itimerval) { { 0, usec }, tv });
+	clock_gettime(CLOCK_PROCESS_CPUTIME_ID,&ts);
+	return timespec_to_ns(&ts);
+}
 
-	if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
-		return -errno;
+long long os_nsecs(void)
+{
+	struct timespec ts;
 
-	return 0;
+	clock_gettime(CLOCK_MONOTONIC,&ts);
+	return timespec_to_ns(&ts);
 }
-#endif
 
-void idle_sleep(unsigned long long nsecs)
+/**
+ * os_idle_sleep() - sleep for a given time of nsecs
+ * @nsecs: nanoseconds to sleep
+ */
+void os_idle_sleep(unsigned long long nsecs)
 {
 	struct timespec ts;
 
-	/*
-	 * nsecs can come in as zero, in which case, this starts a
-	 * busy loop.  To prevent this, reset nsecs to the tick
-	 * interval if it is zero.
-	 */
-	if (nsecs == 0)
-		nsecs = UM_NSEC_PER_SEC / UM_HZ;
+	if (nsecs <= 0) {
+		return;
+	}
 
-	nsecs = sleep_time(nsecs);
-	ts = ((struct timespec) { .tv_sec	= nsecs / UM_NSEC_PER_SEC,
-				  .tv_nsec	= nsecs % UM_NSEC_PER_SEC });
+	ts = ((struct timespec) {
+			.tv_sec  = nsecs / UM_NSEC_PER_SEC,
+			.tv_nsec = nsecs % UM_NSEC_PER_SEC
+	});
 
-	if (nanosleep(&ts, &ts) == 0)
+	/*
+	 * Relay the signal if clock_nanosleep is interrupted.
+	 */
+	if (clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL)) {
 		deliver_alarm();
-	after_sleep_interval(&ts);
+	}
 }
diff --git a/arch/x86/um/stub_32.S b/arch/x86/um/stub_32.S
index b972649..9881680 100644
--- a/arch/x86/um/stub_32.S
+++ b/arch/x86/um/stub_32.S
@@ -1,6 +1,5 @@
 #include <as-layout.h>
 
-	.globl syscall_stub
 .section .__syscall_stub, "ax"
 
 	.globl batch_syscall_stub
diff --git a/arch/x86/um/stub_64.S b/arch/x86/um/stub_64.S
index 7160b20..ba914b3 100644
--- a/arch/x86/um/stub_64.S
+++ b/arch/x86/um/stub_64.S
@@ -1,25 +1,9 @@
 #include <as-layout.h>
 
-	.globl syscall_stub
 .section .__syscall_stub, "ax"
-syscall_stub:
-	syscall
-	/* We don't have 64-bit constants, so this constructs the address
-	 * we need.
-	 */
-	movq	$(STUB_DATA >> 32), %rbx
-	salq	$32, %rbx
-	movq	$(STUB_DATA & 0xffffffff), %rcx
-	or	%rcx, %rbx
-	movq	%rax, (%rbx)
-	int3
-
 	.globl batch_syscall_stub
 batch_syscall_stub:
-	mov	$(STUB_DATA >> 32), %rbx
-	sal	$32, %rbx
-	mov	$(STUB_DATA & 0xffffffff), %rax
-	or	%rax, %rbx
+	mov	$(STUB_DATA), %rbx
 	/* load pointer to first operation */
 	mov	%rbx, %rsp
 	add	$0x10, %rsp