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Re: [uml-devel] [PATCH] um: Switch clocksource to hrtimers
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From: Richard W. <ri...@no...> - 2015-08-15 08:15:28
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Am 09.08.2015 um 19:53 schrieb Thomas Meyer:
> Switch the UML clocksource from interval timers to posix interval timers and
> move to a monotonic timer.
>
> This fixes suspend&resume related timer issues and improves network performance
> as TCP state machines are now fed with the correct time; also correct QoS and
> traffic shaping.
The patch is rather big. Please describe in your commit message how exactly
it works and why.
It changes many internals.
> Signed-off-by: Thomas Meyer <th...@m3...>
Please honor also the original author of the patch.
> ---
> arch/um/Makefile | 2 +-
> arch/um/include/shared/os.h | 15 +-
> arch/um/include/shared/skas/stub-data.h | 5 +-
> arch/um/include/shared/timer-internal.h | 13 ++
> arch/um/kernel/process.c | 6 +-
> arch/um/kernel/skas/clone.c | 5 -
> arch/um/kernel/skas/mmu.c | 2 +
> arch/um/kernel/time.c | 80 +++++++----
> arch/um/os-Linux/internal.h | 1 -
> arch/um/os-Linux/main.c | 6 +-
> arch/um/os-Linux/process.c | 5 +
> arch/um/os-Linux/signal.c | 35 +++--
> arch/um/os-Linux/skas/process.c | 44 ++----
> arch/um/os-Linux/time.c | 248 ++++++++++++++++----------------
> 14 files changed, 234 insertions(+), 233 deletions(-)
> create mode 100644 arch/um/include/shared/timer-internal.h
> delete mode 100644 arch/um/os-Linux/internal.h
>
> diff --git a/arch/um/Makefile b/arch/um/Makefile
> index 098ab33..eb79b4b 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/include/shared/os.h b/arch/um/include/shared/os.h
> index ad3fa3a..7519c98 100644
> --- a/arch/um/include/shared/os.h
> +++ b/arch/um/include/shared/os.h
> @@ -183,6 +183,7 @@ 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 +218,7 @@ 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);
> @@ -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..e09d8fd 100644
> --- a/arch/um/include/shared/skas/stub-data.h
> +++ b/arch/um/include/shared/skas/stub-data.h
> @@ -6,12 +6,11 @@
> #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 68b9119..2ce38c1 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
> @@ -201,11 +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);
> + 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..498148b 100644
> --- a/arch/um/kernel/skas/clone.c
> +++ b/arch/um/kernel/skas/clone.c
> @@ -35,11 +35,6 @@ stub_clone_handler(void)
> if (err)
> goto out;
>
> - err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
> - (long) &data->timer, 0);
> - if (err)
> - goto out;
> -
By removing this call from our clone stub, you change the way how SKAS0
works. Please explain why this is needed.
> 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..42e2988 100644
> --- a/arch/um/kernel/skas/mmu.c
> +++ b/arch/um/kernel/skas/mmu.c
> @@ -61,10 +61,12 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
> if (current->mm != NULL && current->mm != &init_mm)
> from_mm = ¤t->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();
Why do we have to block signals here?
> if (to_mm->id.u.pid < 0) {
> ret = to_mm->id.u.pid;
> diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
> index 117568d..29f1125 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
> */
> @@ -7,11 +8,15 @@
> #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)
> {
> @@ -22,18 +27,20 @@ void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *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 +48,79 @@ 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);
Why did you replace "delta + 1" by "delta"?
> }
>
> -static struct clock_event_device itimer_clockevent = {
> - .name = "itimer",
> +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_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);
> + if (get_current()->mm != NULL)
> + {
> + 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);
> - if (err != 0)
> + err = request_irq(TIMER_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 +128,6 @@ 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/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..6e36f0f 100644
> --- a/arch/um/os-Linux/main.c
> +++ b/arch/um/os-Linux/main.c
> @@ -163,13 +163,13 @@ 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..f3bd983 100644
> --- a/arch/um/os-Linux/process.c
> +++ b/arch/um/os-Linux/process.c
> @@ -89,6 +89,11 @@ 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..e04a4cd 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 };
> + [SIGALRM] = timer_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 != SIGALRM))
> 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 SIGALRM_BIT 1
> +#define SIGALRM_MASK (1 << SIGALRM_BIT)
>
> static int signals_enabled;
> static unsigned int signals_pending;
> @@ -78,36 +78,34 @@ 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(®s, mc);
> - regs.is_user = 0;
> - unblock_signals();
> - timer_handler(SIGVTALRM, NULL, ®s);
> + timer_handler(SIGALRM, NULL, ®s);
> }
>
> -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 timer_set_signal_handler(void)
> {
> - set_handler(SIGVTALRM);
> + set_handler(SIGALRM);
> }
>
> void set_sigstack(void *sig_stack, int size)
> @@ -131,10 +129,9 @@ 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 +185,9 @@ 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 +280,8 @@ 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..5ae4752 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 << SIGALRM) | (1 << SIGWINCH))
>
> /* Signals that the stub will finish with - anything else is an error */
> #define STUB_DONE_MASK (1 << SIGTRAP)
> @@ -179,19 +179,13 @@ 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 +276,7 @@ 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 +309,6 @@ 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 +317,8 @@ 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 +388,7 @@ 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 +436,6 @@ __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 +447,10 @@ 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
> + });
As written above, you change the way how SKAS0 works, this needs
much more explaination.
> 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..0e2bb7d 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 +11,172 @@
> #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;
> + }
> +
> + return its.it_value.tv_nsec;
> +}
>
> -static void deliver_alarm(void)
> +int os_timer_one_shot(int ticks)
> {
> - unsigned long long this_tick = os_nsecs();
> - int one_tick = UM_NSEC_PER_SEC / UM_HZ;
> + struct itimerspec its;
> + unsigned long long nsec;
> + unsigned long sec;
>
> - /* Protection against the host's time going backwards */
> - if ((last_tick != 0) && (this_tick < last_tick))
> - this_tick = last_tick;
> + nsec = (ticks + 1);
> + sec = nsec / UM_NSEC_PER_SEC;
> + nsec = nsec % UM_NSEC_PER_SEC;
>
> - if (last_tick == 0)
> - last_tick = this_tick - one_tick;
> + its.it_value.tv_sec = nsec / UM_NSEC_PER_SEC;
> + its.it_value.tv_nsec = nsec;
>
> - skew += this_tick - last_tick;
> + its.it_interval.tv_sec = 0;
> + its.it_interval.tv_nsec = 0; // we cheat here
>
> - while (skew >= one_tick) {
> - alarm_handler(SIGVTALRM, NULL, NULL);
> - skew -= one_tick;
> - }
> -
> - 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);
> }
>
Thanks,
//richard
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