On Sun, May 10, 2015 at 1:14 AM, Thomas Meyer <tho...@m3y3r.de> wrote:
> Hi,
>
> Changes:
> - also create posix timer in stub_clone_handler()
> - incorporated antons remarks

Hm, this patch does a *lot* more than the changelog says.

>
> diff --git a/arch/um/Makefile b/arch/um/Makefile
> index 17d4460..a4a434f 100644
> --- a/arch/um/Makefile
> +++ b/arch/um/Makefile
> @@ -130,7 +130,7 @@ 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/include/asm/irq.h b/arch/um/include/asm/irq.h
> index 4a2037f..0f2a5b1 100644
> --- a/arch/um/include/asm/irq.h
> +++ b/arch/um/include/asm/irq.h
> @@ -16,8 +16,9 @@
>  #define TELNETD_IRQ            12
>  #define XTERM_IRQ              13
>  #define RANDOM_IRQ             14
> +#define HRTIMER_IRQ            15
>
> -#define LAST_IRQ RANDOM_IRQ
> +#define LAST_IRQ HRTIMER_IRQ
>  #define NR_IRQS (LAST_IRQ + 1)
>
>  #endif
> diff --git a/arch/um/include/shared/as-layout.h 
> b/arch/um/include/shared/as-layout.h
> index ca1843e..798aa6e 100644
> --- a/arch/um/include/shared/as-layout.h
> +++ b/arch/um/include/shared/as-layout.h
> @@ -17,7 +17,7 @@
>
>  /* Some constant macros are used in both assembler and
>   * C code.  Therefore we cannot annotate them always with
> - * 'UL' and other type specifiers unilaterally.  We
> + * 'UL' and other type specifiers unilaterally. We
>   * use the following macros to deal with this.
>   */
>
> @@ -28,6 +28,13 @@
>  #define _UML_AC(X, Y)  __UML_AC(X, Y)
>  #endif
>
> +/**
> + * userspace stub address space layout:
> + * Below macros define the layout of the stub code and data
> + * which are mapped in each userspace process:
> + *  - one page of code located at 0x100000 followed by
> + *  - one page of data
> + */
>  #define STUB_START _UML_AC(, 0x100000)
>  #define STUB_CODE _UML_AC((unsigned long), STUB_START)
>  #define STUB_DATA _UML_AC((unsigned long), STUB_CODE + UM_KERN_PAGE_SIZE)
> diff --git a/arch/um/include/shared/kern_util.h 
> b/arch/um/include/shared/kern_util.h
> index 83a91f9..0282b36 100644
> --- a/arch/um/include/shared/kern_util.h
> +++ b/arch/um/include/shared/kern_util.h
> @@ -37,6 +37,7 @@ extern void initial_thread_cb(void (*proc)(void *), void 
> *arg);
>  extern int is_syscall(unsigned long addr);
>
>  extern void timer_handler(int sig, struct siginfo *unused_si, struct 
> uml_pt_regs *regs);
> +extern void hrtimer_handler(int sig, struct siginfo *unused_si, struct 
> uml_pt_regs *regs);
>
>  extern int start_uml(void);
>  extern void paging_init(void);
> diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
> index d824528..7f7368b 100644
> --- a/arch/um/include/shared/os.h
> +++ b/arch/um/include/shared/os.h
> @@ -217,7 +217,8 @@ extern int set_umid(char *name);
>  extern char *get_umid(void);
>
>  /* signal.c */
> -extern void timer_init(void);
> +extern void uml_timer_set_signal_handler(void);
> +extern void uml_hrtimer_set_signal_handler(void);
>  extern void set_sigstack(void *sig_stack, int size);
>  extern void remove_sigstack(void);
>  extern void set_handler(int sig);
> @@ -238,12 +239,16 @@ 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,
> diff --git a/arch/um/include/shared/skas/stub-data.h 
> b/arch/um/include/shared/skas/stub-data.h
> index f6ed92c..f98b9e2 100644
> --- a/arch/um/include/shared/skas/stub-data.h
> +++ b/arch/um/include/shared/skas/stub-data.h
> @@ -6,12 +6,12 @@
>  #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;
> +       struct itimerspec 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..afdc6dc
> --- /dev/null
> +++ b/arch/um/include/shared/timer-internal.h
> @@ -0,0 +1,18 @@
> +/*
> + * 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
> +
> +extern void timer_lock(void);
> +extern void timer_unlock(void);
> +
> +extern long long hrtimer_disable(void);
> +
> +#endif
> diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
> index 23cb935..4c1966a 100644
> --- a/arch/um/kernel/irq.c
> +++ b/arch/um/kernel/irq.c
> @@ -338,20 +338,20 @@ static struct irq_chip normal_irq_type = {
>         .irq_unmask = dummy,
>  };
>
> -static struct irq_chip SIGVTALRM_irq_type = {
> -       .name = "SIGVTALRM",
> -       .irq_disable = dummy,
> -       .irq_enable = dummy,
> -       .irq_ack = dummy,
> -       .irq_mask = dummy,
> -       .irq_unmask = dummy,
> +static struct irq_chip SIGUSR2_irq_type = {
> +       .name = "SIGUSR2",
> +       .irq_disable = dummy,
> +       .irq_enable = dummy,
> +       .irq_ack = dummy,
> +       .irq_mask = dummy,
> +       .irq_unmask = dummy,
>  };
>
>  void __init init_IRQ(void)
>  {
>         int i;
>
> -       irq_set_chip_and_handler(TIMER_IRQ, &SIGVTALRM_irq_type, 
> handle_edge_irq);
> +       irq_set_chip_and_handler(HRTIMER_IRQ, &SIGUSR2_irq_type, 
> handle_edge_irq);
>
>         for (i = 1; i < NR_IRQS; i++)
>                 irq_set_chip_and_handler(i, &normal_irq_type, 
> handle_edge_irq);
> diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
> index 9034fc8..5f6642d 100644
> --- a/arch/um/kernel/physmem.c
> +++ b/arch/um/kernel/physmem.c
> @@ -119,14 +119,23 @@ void __init setup_physmem(unsigned long start, unsigned 
> long reserve_end,
>                      len - bootmap_size - reserve);
>  }
>
> +/**
> + * phys_mapping() - maps a physical address to an offset address
> + * phys:    the physical address
> + * offset_out:  the offset in the memory map area
> + *
> + * Returns an file descriptor, or -1 when unknown physical address
> + */
>  int phys_mapping(unsigned long phys, unsigned long long *offset_out)
>  {
>         int fd = -1;
>
> +       /* first check normal memory */
>         if (phys < physmem_size) {
>                 fd = physmem_fd;
>                 *offset_out = phys;
>         }
> +       /* than check io memory */
>         else if (phys < __pa(end_iomem)) {
>                 struct iomem_region *region = iomem_regions;
>
> @@ -140,6 +149,7 @@ int phys_mapping(unsigned long phys, unsigned long long 
> *offset_out)
>                         region = region->next;
>                 }
>         }
> +       /* last check highmem */
>         else if (phys < __pa(end_iomem) + highmem) {
>                 fd = physmem_fd;
>                 *offset_out = phys - iomem_size;
> diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
> index 68b9119..b8a8d10 100644
> --- a/arch/um/kernel/process.c
> +++ b/arch/um/kernel/process.c
> @@ -27,6 +27,7 @@
>  #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
> @@ -201,12 +202,8 @@ 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);
> -       local_irq_enable();
> +       os_idle_sleep(UM_NSEC_PER_SEC / UM_HZ);
>  }
>
>  int __cant_sleep(void) {
> diff --git a/arch/um/kernel/skas/clone.c b/arch/um/kernel/skas/clone.c
> index 289771d..5f283b1 100644
> --- a/arch/um/kernel/skas/clone.c
> +++ b/arch/um/kernel/skas/clone.c
> @@ -20,37 +20,63 @@
>   * on some systems.
>   */
>
> +/**
> + * stub_clone_handler() - userspace clone handler stub
> + *
> + * this stub clone hanlder is mmaped(?)/available in all userspace
> + * processes. It's used to copy an mm context from an fork syscall in the
> + * traced userspace process
> + */
>  void __attribute__ ((__section__ (".__syscall_stub")))
>  stub_clone_handler(void)
>  {
>         struct stub_data *data = (struct stub_data *) STUB_DATA;
> +       struct sigevent sev;
> +       timer_t timerid;
>         long err;
>
> +       /* clone "from" process */
>         err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
>                             STUB_DATA + UM_KERN_PAGE_SIZE / 2 - sizeof(void 
> *));
> -       if (err != 0)
> +       /* Parent: exit here, child, continue */
> +       if (err != 0) {
>                 goto out;
> +       }
>
> +       /* set child to ptrace */
>         err = stub_syscall4(__NR_ptrace, PTRACE_TRACEME, 0, 0, 0);
>         if (err)
>                 goto out;
>
> -       err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
> -                           (long) &data->timer, 0);
> +       /* create a new posix interval timer */
> +       sev.sigev_notify = SIGEV_SIGNAL;
> +       sev.sigev_signo = SIGUSR2;
> +       sev.sigev_value.sival_ptr = NULL;
> +
> +       err = stub_syscall3(__NR_timer_create, CLOCK_MONOTONIC,
> +                               (long) &sev, (long) &timerid);
>         if (err)
>                 goto out;
>
> +       /* set interval to the given value from copy_context_skas0() */
> +       err = stub_syscall4(__NR_timer_settime, (long) timerid, 0l,
> +                                               (long) &data->timer, 0l);
> +       if (err)
> +               goto out;
> +
> +       /* switch to new stack */
>         remap_stack(data->fd, data->offset);
>         goto done;
>
>   out:
>         /*
> -        * save current result.
> -        * Parent: pid;
> -        * child: retcode of mmap already saved and it jumps around this
> -        * assignment
> +        * Save current result.
> +        * - Parent: pid from clone() call
> +        * - Child:  "retcode of mmap already saved and it jumps around this
> +        *            assignment"???
>          */
>         data->err = err;
> +
>   done:
>         trap_myself();
>  }
> diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
> index 94abdcc..df9c9ab 100644
> --- a/arch/um/kernel/skas/mmu.c
> +++ b/arch/um/kernel/skas/mmu.c
> @@ -47,6 +47,13 @@ static int init_stub_pte(struct mm_struct *mm, unsigned 
> long proc,
>         return -ENOMEM;
>  }
>
> +/**
> + * init_new_context() - creates or copies an mm context
> + * @task:      the belonging task
> + * @mm:                the mm struct to be setup/allocated
> + *
> + * called by mm_init() (kernel/fork.c)
> + */
>  int init_new_context(struct task_struct *task, struct mm_struct *mm)
>  {
>         struct mm_context *from_mm = NULL;
> @@ -59,13 +66,15 @@ int init_new_context(struct task_struct *task, struct 
> mm_struct *mm)
>                 goto out;
>
>         to_mm->id.stack = stack;
> -       if (current->mm != NULL && current->mm != &init_mm)
> +       if (current->mm != NULL && current->mm != &init_mm) {
>                 from_mm = &current->mm->context;
> +       }
>
> -       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);
> +       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);
> +       }
>
>         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 527fa58..2b0c35a 100644
> --- a/arch/um/kernel/skas/process.c
> +++ b/arch/um/kernel/skas/process.c
> @@ -43,6 +43,9 @@ int __init start_uml(void)
>                                  &init_task.thread.switch_buf);
>  }
>
> +/**
> + * current_stub_stack() - returns the address of the current mm stack
> + */
>  unsigned long current_stub_stack(void)
>  {
>         if (current->mm == NULL)
> diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
> index 117568d..ed64037 100644
> --- a/arch/um/kernel/time.c
> +++ b/arch/um/kernel/time.c
> @@ -1,4 +1,5 @@
>  /*
> + * Copyright (C) 2012-2014 Cisco Systems
>   * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
>   * Licensed under the GPL
>   */
> @@ -8,32 +9,36 @@
>  #include <linux/interrupt.h>
>  #include <linux/jiffies.h>
>  #include <linux/threads.h>
> +#include <linux/spinlock.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)
> +void hrtimer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs 
> *regs)
>  {
>         unsigned long flags;
>
>         local_irq_save(flags);
> -       do_IRQ(TIMER_IRQ, regs);
> +       do_IRQ(HRTIMER_IRQ, regs);
>         local_irq_restore(flags);
>  }
>
> -static void itimer_set_mode(enum clock_event_mode mode,
> +static void timer_set_mode(enum clock_event_mode mode,
>                             struct clock_event_device *evt)
>  {
>         switch (mode) {
>         case CLOCK_EVT_MODE_PERIODIC:
> -               set_interval();
> +               os_timer_set_interval(NULL, NULL);
>                 break;
>
> +       case CLOCK_EVT_MODE_ONESHOT:
> +               os_timer_one_shot(1);
> +
>         case CLOCK_EVT_MODE_SHUTDOWN:
>         case CLOCK_EVT_MODE_UNUSED:
> -       case CLOCK_EVT_MODE_ONESHOT:
> -               disable_timer();
> +               os_timer_disable();
>                 break;
>
>         case CLOCK_EVT_MODE_RESUME:
> @@ -41,68 +46,74 @@ static void itimer_set_mode(enum clock_event_mode mode,
>         }
>  }
>
> -static int itimer_next_event(unsigned long delta,
> +static int timer_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 struct clock_event_device timer_clockevent = {
> +       .name           = "timer",
>         .rating         = 250,
>         .cpumask        = cpu_all_mask,
>         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
> -       .set_mode       = itimer_set_mode,
> -       .set_next_event = itimer_next_event,
> -       .shift          = 32,
> +       .set_mode       = timer_set_mode,
> +       .set_next_event = timer_next_event,
> +       .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)
> +static irqreturn_t um_timer_irq(int irq, void *dev)
>  {
> -       (*itimer_clockevent.event_handler)(&itimer_clockevent);
> +       (*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);
> -       if (err != 0)
> +       err = request_irq(HRTIMER_IRQ, um_timer_irq, IRQF_TIMER, "hr timer", 
> NULL);
> +       if (err != 0) {
>                 printk(KERN_ERR "register_timer : request_irq failed - "
>                        "errno = %d\n", -err);
> +               return;
> +    }
> +
> +    err = os_timer_create(NULL);
> +    if (err != 0) {
> +        printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
> +        return;
> +    }
>
> -       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 = 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);
> @@ -110,6 +121,6 @@ void read_persistent_clock(struct timespec *ts)
>
>  void __init time_init(void)
>  {
> -       timer_init();
> -       late_time_init = setup_itimer;
> +       uml_hrtimer_set_signal_handler();
> +       late_time_init = timer_setup;
>  }
> 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..bd5907e 100644
> --- a/arch/um/os-Linux/main.c
> +++ b/arch/um/os-Linux/main.c
> @@ -168,8 +168,8 @@ int __init main(int argc, char **argv, char **envp)
>          * 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/signal.c b/arch/um/os-Linux/signal.c
> index 7b605e4..ee6db2e 100644
> --- a/arch/um/os-Linux/signal.c
> +++ b/arch/um/os-Linux/signal.c
> @@ -13,7 +13,6 @@
>  #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 +22,8 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct 
> uml_pt_regs *) = {
>         [SIGBUS]        = bus_handler,
>         [SIGSEGV]       = segv_handler,
>         [SIGIO]         = sigio_handler,
> -       [SIGVTALRM]     = timer_handler };
> +       [SIGUSR2]       = hrtimer_handler
> +};
>
>  static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
>  {
> @@ -38,7 +38,7 @@ 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 != SIGVTALRM) && (sig 
> != SIGUSR2))
>                 unblock_signals();
>
>         (*sig_info[sig])(sig, si, &r);
> @@ -55,8 +55,8 @@ 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 SIGUSR2_BIT 2
> +#define SIGUSR2_MASK (1 << SIGUSR2_BIT)
>
>  static int signals_enabled;
>  static unsigned int signals_pending;
> @@ -78,46 +78,47 @@ void sig_handler(int sig, struct siginfo *si, mcontext_t 
> *mc)
>         set_signals(enabled);
>  }
>
> -static void real_alarm_handler(mcontext_t *mc)
> +static void real_hralarm_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);
> +       hrtimer_handler(SIGUSR2, NULL, &regs);
>  }
>
> -void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
> +void hralarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
>  {
>         int enabled;
>
>         enabled = signals_enabled;
>         if (!signals_enabled) {
> -               signals_pending |= SIGVTALRM_MASK;
> +               signals_pending |= SIGUSR2_MASK;
>                 return;
>         }
>
>         block_signals();
> -
> -       real_alarm_handler(mc);
> +       real_hralarm_handler(mc);
>         set_signals(enabled);
>  }
>
> -void timer_init(void)
> +void uml_hrtimer_set_signal_handler(void)
>  {
> -       set_handler(SIGVTALRM);
> +       set_handler(SIGUSR2);
>  }
>
>  void set_sigstack(void *sig_stack, int size)
>  {
> -       stack_t stack = ((stack_t) { .ss_flags  = 0,
> -                                    .ss_sp     = (__ptr_t) sig_stack,
> -                                    .ss_size   = size - sizeof(void *) });
> +       stack_t stack = ((stack_t) {
> +                   .ss_flags = 0,
> +                               .ss_sp    = (__ptr_t) sig_stack,
> +                               .ss_size  = size - sizeof(void *)
> +       });
>
> -       if (sigaltstack(&stack, NULL) != 0)
> +       if (sigaltstack(&stack, NULL) != 0) {
>                 panic("enabling signal stack failed, errno = %d\n", errno);
> +       }
>  }
>
>  static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) 
> = {
> @@ -129,10 +130,9 @@ static void (*handlers[_NSIG])(int sig, struct siginfo 
> *si, mcontext_t *mc) = {
>
>         [SIGIO] = sig_handler,
>         [SIGWINCH] = sig_handler,
> -       [SIGVTALRM] = alarm_handler
> +       [SIGUSR2] = hralarm_handler
>  };
>
> -
>  static void hard_handler(int sig, siginfo_t *si, void *p)
>  {
>         struct ucontext *uc = p;
> @@ -176,6 +176,13 @@ static void hard_handler(int sig, siginfo_t *si, void *p)
>         } while (pending);
>  }
>
> +/**
> + * set_handler() - enable signal in process' signal mask
> + * @sig:    The signal to enable
> + *
> + * Enable the given signal in the process' signal mask and
> + * attach hard_handler() as handler routine
> + */
>  void set_handler(int sig)
>  {
>         struct sigaction action;
> @@ -186,9 +193,9 @@ 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, SIGUSR2);
>
>         if (sig == SIGSEGV)
>                 flags |= SA_NODEFER;
> @@ -281,8 +288,8 @@ 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 & SIGUSR2_MASK)
> +                       real_hralarm_handler(NULL);
>         }
>  }
>
> @@ -298,9 +305,11 @@ int set_signals(int enable)
>                 return enable;
>
>         ret = signals_enabled;
> -       if (enable)
> +       if (enable) {
>                 unblock_signals();
> -       else block_signals();
> +       } else {
> +           block_signals();
> +    }
>
>         return ret;
>  }
> diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
> index 7a97775..30065e1 100644
> --- a/arch/um/os-Linux/skas/process.c
> +++ b/arch/um/os-Linux/skas/process.c
> @@ -45,7 +45,7 @@ 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 << SIGVTALRM) | (1 << SIGWINCH) | (1 << SIGUSR2))
>
>  /* Signals that the stub will finish with - anything else is an error */
>  #define STUB_DONE_MASK (1 << SIGTRAP)
> @@ -176,17 +176,59 @@ static void handle_trap(int pid, struct uml_pt_regs 
> *regs,
>
>  extern int __syscall_stub_start;
>
> +/**
> + * userspace_tramp() - userspace trampoline
> + * @stack:  The address of the stub stack used for the new process
> + *          (used for SIGSEGV handling).
> + *
> + * The trampoline does execute as a new process after clone()
> + * For each new userspace process the below code sets up
> + * all necessary data:
> + * 1.) enable ptrace from parent (the uml kernel)
> + * 2.) Setup signal handling. Signals are inherited by the parent, i.e
> + *     the uml kernel
> + * 3.) Create and start an posix (interval) timer for this process.
> + *     This timer will emulate the kernel timer ticks.
> + *     The timer signal will be processed by the kernel process in 
> userspace()
> + * 4.) Map stub code page in the new process, i.e. the
> + *     userspace process:
> + *     The stub codes is used to catch syscalls from the userspace to
> + *     the kernel.
> + *     See linker scripts arch/um/kernel/dyn.lds.S (dynamic) resp.
> + *                        arch/um/kernel/uml.lds.S (static)
> + *     for __syscall_stub_start defintion and
> + *     arch/um/kernel/skas/clone.c for the stub_handler itself.
> + * 5.) Map stub data page in the new process, i.e. the
> + *     userspace process:
> + *     Setup an SIGSEGV handler into the new process.
> + *     Page faults will be catched and signaled to the kernel via this
> + *     mechanism.
> + *     See arch/x86/um/stub_segv.c for the handler itself.
> + * 6.) Stop the new process and wait for the kernel to SIGCONT it agian
> + *     when it will get scheduled()
> + */
>  static int userspace_tramp(void *stack)
>  {
>         void *addr;
>         int err, fd;
>         unsigned long long offset;
> +       timer_t timer;
> +
> +       struct stub_data *data = (struct stub_data *) stack;
>
>         ptrace(PTRACE_TRACEME, 0, 0, 0);
>
>         signal(SIGTERM, SIG_DFL);
>         signal(SIGWINCH, SIG_IGN);
> -       err = set_interval();
> +
> +       err = os_timer_create(&timer);
> +       if (err) {
> +               printk(UM_KERN_ERR "userspace_tramp - creation of timer 
> failed, "
> +                      "errno = %d\n", err);
> +               exit(1);
> +       }
> +
> +       err = os_timer_set_interval(&timer, &data->timer);
>         if (err) {
>                 printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
>                        "errno = %d\n", err);
> @@ -246,11 +288,18 @@ static int userspace_tramp(void *stack)
>  #define NR_CPUS 1
>  int userspace_pid[NR_CPUS];
>
> +/**
> + * start_userspace() - start a new userspace process with a new mm context
> + * @stub_stack: Address of the new process' stack
> + *
> + * called by init_new_context()
> + */
>  int start_userspace(unsigned long stub_stack)
>  {
>         void *stack;
>         unsigned long sp;
>         int pid, status, n, flags, err;
> +       struct stub_data *data = (struct stub_data *) stub_stack;
>
>         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
>                      PROT_READ | PROT_WRITE | PROT_EXEC,
> @@ -266,6 +315,14 @@ int start_userspace(unsigned long stub_stack)
>
>         flags = CLONE_FILES | SIGCHLD;
>
> +       *data = ((struct stub_data) {
> +                       .timer  = ((struct itimerspec)
> +                               { .it_value.tv_sec  = 0,
> +                                 .it_value.tv_nsec = os_timer_remain(NULL),
> +                                 .it_interval.tv_sec  = 0,
> +                                 .it_interval.tv_nsec = UM_NSEC_PER_SEC / 
> UM_HZ })
> +       });
> +
>         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
>         if (pid < 0) {
>                 err = -errno;
> @@ -313,10 +370,15 @@ int start_userspace(unsigned long stub_stack)
>         return err;
>  }
>
> +/**
> + * userspace() - user space control loop
> + * @regs:      the register's save memory
> + *
> + * The main loop that traces and controls each spwaned userspace
> + * process
> + */
>  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 +387,8 @@ 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
> @@ -388,32 +445,19 @@ void userspace(struct uml_pt_regs *regs)
>                         switch (sig) {
>                         case SIGSEGV:
>                                 if (PTRACE_FULL_FAULTINFO) {
> -                                       get_skas_faultinfo(pid,
> -                                                          &regs->faultinfo);
> -                                       (*sig_info[SIGSEGV])(SIGSEGV, (struct 
> siginfo *)&si,
> -                                                            regs);
> +                                       
> get_skas_faultinfo(pid,&regs->faultinfo);
> +                                       (*sig_info[SIGSEGV])(SIGSEGV, (struct 
> siginfo *)&si, regs);
> +                               } else {
> +                                       handle_segv(pid, regs);
>                                 }
> -                               else handle_segv(pid, regs);
>                                 break;
>                         case SIGTRAP + 0x80:
> -                               handle_trap(pid, regs, local_using_sysemu);
> +                               handle_trap(pid, regs, local_using_sysemu);
>                                 break;
>                         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();
> -                               break;
> +                       case SIGUSR2:
>                         case SIGIO:
>                         case SIGILL:
>                         case SIGBUS:
> @@ -448,8 +492,7 @@ static int __init init_thread_regs(void)
>         thread_regs[REGS_IP_INDEX] = STUB_CODE +
>                                 (unsigned long) stub_clone_handler -
>                                 (unsigned long) &__syscall_stub_start;
> -       thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
> -               sizeof(void *);
> +       thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE - 
> sizeof(void *);
>  #ifdef __SIGNAL_FRAMESIZE
>         thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
>  #endif
> @@ -458,26 +501,51 @@ static int __init init_thread_regs(void)
>
>  __initcall(init_thread_regs);
>
> +/**
> + * copy_context_skas0() - copy an mm context
> + * new_stack:  void pointer of new stack, a zeroed page
> + * pid:                        the pid of the mm parent, this proces is 
> cloned
> + *                             into a new one
> + *
> + * Copy an mm context from an existing task
> + * 1.) get file descriptor and offset of the mmaped new_stack
> + * 2.) set current stub stack's data: file descriptor, offset and timer data
> + * 3.) Restore parents registers to init_thread_regs()
> + * 4.) Continue parent (==from_mm) in stub_clone_handler(), see also
> + *     init_thread_regs(). This will clone a new process with same
> + *     mm.
> + * 5.)
> + *
> + * Returns the PID of the new process
> + */
>  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;
>         struct stub_data *child_data = (struct stub_data *) new_stack;
>         unsigned long long new_offset;
> +
>         int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
>
>         /*
>          * 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,
> +                       .timer  = ((struct itimerspec)
> +                                            { .it_value.tv_sec  = 0,
> +                                              .it_value.tv_nsec = 
> os_timer_remain(NULL),
> +                                              .it_interval.tv_sec  = 0,
> +                                              .it_interval.tv_nsec = 
> UM_NSEC_PER_SEC / UM_HZ })
> +       });
> +
> +       /* set parents regs
> +        * this set the registers to the saved registers done in the initcall
> +        * init_thread_regs()
> +        */
>         err = ptrace_setregs(pid, thread_regs);
>         if (err < 0) {
>                 err = -errno;
> @@ -486,6 +554,7 @@ int copy_context_skas0(unsigned long new_stack, int pid)
>                 return err;
>         }
>
> +       /* set parents fp registers */
>         err = put_fp_registers(pid, thread_fp_regs);
>         if (err < 0) {
>                 printk(UM_KERN_ERR "copy_context_skas0 : put_fp_registers "
> @@ -493,7 +562,9 @@ int copy_context_skas0(unsigned long new_stack, int pid)
>                 return err;
>         }
>
> -       /* set a well known return code for detection of child write failure 
> */
> +       /* set a well known return code for detection of child write failure,
> +        * i.e. on the new stack
> +        */
>         child_data->err = 12345678;
>
>         /*
> @@ -508,8 +579,10 @@ int copy_context_skas0(unsigned long new_stack, int pid)
>                 return err;
>         }
>
> +       /* wait for parents stub_clone_handler() to finish */
>         wait_stub_done(pid);
>
> +       /* get childs pid, the pid of the cloned parent process */
>         pid = data->err;
>         if (pid < 0) {
>                 printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
> diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
> index e9824d5..5a7f49c 100644
> --- a/arch/um/os-Linux/time.c
> +++ b/arch/um/os-Linux/time.c
> @@ -1,4 +1,5 @@
>  /*
> + * Copyright (C) 2012-2014 Cisco Systems
>   * Copyright (C) 2000 - 2007 Jeff Dike (jdike{addtoit,linux.intel}.com)
>   * Licensed under the GPL
>   */
> @@ -10,177 +11,177 @@
>  #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) {
>
> -long long disable_timer(void)
> -{
> -       struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } });
> -       long long remain, max = UM_NSEC_PER_SEC / UM_HZ;
> +       struct sigevent sev;
> +       timer_t* t = timer;
>
> -       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;
> +       sev.sigev_notify = SIGEV_SIGNAL;
> +       sev.sigev_signo = SIGUSR2; /* note - hrtimer now has its own signal */
> +       sev.sigev_value.sival_ptr = &event_high_res_timer;
>
> -       return remain;
> +       if (timer_create(
> +               CLOCK_MONOTONIC,
> +               &sev,
> +               t) == -1) {
> +               return -1;
> +       }
> +       return 0;
>  }
>
> -long long os_nsecs(void)
> +int os_timer_set_interval(void* timer, void* i)
>  {
> -       struct timeval tv;
> +       struct itimerspec its;
> +       unsigned long long nsec;
> +       timer_t* t = timer;
> +       struct itimerspec* its_in = i;
>
> -       gettimeofday(&tv, NULL);
> -       return timeval_to_ns(&tv);
> -}
> +       if(t == NULL) {
> +               t = &event_high_res_timer;
> +       }
> +
> +       nsec = UM_NSEC_PER_SEC / UM_HZ;
> +
> +       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;
> +       }
> +
> +       its.it_interval.tv_sec = 0;
> +       its.it_interval.tv_nsec = nsec;
> +
> +       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;
> +
> +       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 inline long long timespec_to_us(const struct timespec *ts)
> +long long os_vnsecs(void)
>  {
> -       return ((long long) ts->tv_sec * UM_USEC_PER_SEC) +
> -               ts->tv_nsec / UM_NSEC_PER_USEC;
> +       struct timespec ts;
> +
> +       clock_gettime(CLOCK_PROCESS_CPUTIME_ID,&ts);
> +       return timespec_to_ns(&ts);
>  }
>
> -static int after_sleep_interval(struct timespec *ts)
> +long long os_nsecs(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;
> -
> -       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 });
> -
> -       if (setitimer(ITIMER_VIRTUAL, &interval, NULL) == -1)
> -               return -errno;
> +       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;
> -
> -       nsecs = sleep_time(nsecs);
> -       ts = ((struct timespec) { .tv_sec       = nsecs / UM_NSEC_PER_SEC,
> -                                 .tv_nsec      = nsecs % UM_NSEC_PER_SEC });
> -
> -       if (nanosleep(&ts, &ts) == 0)
> -               deliver_alarm();
> -       after_sleep_interval(&ts);
> +       if (nsecs <= 0) {
> +               return;
> +       }
> +
> +       ts = ((struct timespec) {
> +                       .tv_sec  = nsecs / UM_NSEC_PER_SEC,
> +                       .tv_nsec = nsecs % UM_NSEC_PER_SEC
> +       });
> +
> +       clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL);
>  }
> diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
> index faee55e..10ecc06 100644
> --- a/arch/um/os-Linux/util.c
> +++ b/arch/um/os-Linux/util.c
> @@ -102,6 +102,7 @@ void os_fix_helper_signals(void)
>         signal(SIGWINCH, SIG_IGN);
>         signal(SIGINT, SIG_DFL);
>         signal(SIGTERM, SIG_DFL);
> +       signal(SIGUSR2, SIG_IGN);
>  }
>
>  void os_dump_core(void)
>
>
>
> ------------------------------------------------------------------------------
> One dashboard for servers and applications across Physical-Virtual-Cloud
> Widest out-of-the-box monitoring support with 50+ applications
> Performance metrics, stats and reports that give you Actionable Insights
> Deep dive visibility with transaction tracing using APM Insight.
> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
> _______________________________________________
> User-mode-linux-devel mailing list
> User-mode-linux-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel



-- 
Thanks,
//richard

------------------------------------------------------------------------------
One dashboard for servers and applications across Physical-Virtual-Cloud 
Widest out-of-the-box monitoring support with 50+ applications
Performance metrics, stats and reports that give you Actionable Insights
Deep dive visibility with transaction tracing using APM Insight.
http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel

Reply via email to