Am 15.08.2015 10:15 vorm. schrieb Richard Weinberger <rich...@nod.at>:
>
> 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.
Will do so!
>
> > Signed-off-by: Thomas Meyer <tho...@m3y3r.de>
>
> Please honor also the original author of the patch.
Sure! Give credit where credit is due!
>
> > ---
> > 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.
Yes, before this patch each userspace process has its own itimer, after this
patch only the uml process that runs the kernel will get a timer tick. The
kernel will then signal the currently active userspace task about the time
event.
>
> > 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?
There is a small time window, when a userspace process forks itself and because
of that is running in the stub code... When this process then receives a timer
signal it gets confused and ends up in a loop. So a quick fix was to disable
the timer interrupts when possibly entering this stub code in the userspace
process.
>
> > 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"?
I think this comes from Anton's original patch and AFAIU was a hack to
guarantee progress with the itimer based solution.
This hack is no longer needed as the new POSIX interval timer are monotonic and
do always progress correctly!
>
>
> > }
> >
> > -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.
Yes, okay. See above. The userspace stub code no longer generates an itimer, so
no timer information needs to be passed here.
>
> > 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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