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Subject[RFC PATCH 25/35] Add Xen time abstractions
Add support for Xen time abstractions. To avoid expensive traps into
the hypervisor, the passage of time is extrapolated from the local TSC
and a set of timestamps and scaling factors exported to the guest via
shared memory. Xen also provides a periodic interrupt facility which
is used to drive updates of xtime and jiffies, and perform the usual
process accounting and profiling.

Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
arch/i386/kernel/Makefile | 6
drivers/xen/core/time.c | 1045 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 1050 insertions(+), 1 deletion(-)
--- linus-2.6.orig/arch/i386/kernel/Makefile
+++ linus-2.6/arch/i386/kernel/Makefile
@@ -9,8 +9,11 @@ obj-y := process.o semaphore.o signal.o
pci-dma.o i386_ksyms.o i387.o bootflag.o \
quirks.o i8237.o topology.o alternative.o

+timers-y := timers/
+timers-$(CONFIG_XEN) :=
+
obj-y += cpu/
-obj-y += timers/
+obj-y += $(timers-y)
obj-y += acpi/
obj-$(CONFIG_X86_BIOS_REBOOT) += reboot.o
obj-$(CONFIG_MCA) += mca.o
@@ -45,6 +48,7 @@ obj-$(CONFIG_SCx200) += scx200.o
hw_irq-y := i8259.o

hw_irq-$(CONFIG_XEN) := ../../../drivers/xen/core/evtchn.o
+time-$(CONFIG_XEN) := ../../../drivers/xen/core/time.o

# vsyscall.o contains the vsyscall DSO images as __initdata.
# We must build both images before we can assemble it.
--- /dev/null
+++ linus-2.6/drivers/xen/core/time.c
@@ -0,0 +1,1045 @@
+/*
+ * time.c
+ *
+ * Copyright (C) 1991, 1992, 1995 Linus Torvalds
+ *
+ * This file contains the PC-specific time handling details:
+ * reading the RTC at bootup, etc..
+ * 1994-07-02 Alan Modra
+ * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
+ * 1995-03-26 Markus Kuhn
+ * fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
+ * precision CMOS clock update
+ * 1996-05-03 Ingo Molnar
+ * fixed time warps in do_[slow|fast]_gettimeoffset()
+ * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
+ * "A Kernel Model for Precision Timekeeping" by Dave Mills
+ * 1998-09-05 (Various)
+ * More robust do_fast_gettimeoffset() algorithm implemented
+ * (works with APM, Cyrix 6x86MX and Centaur C6),
+ * monotonic gettimeofday() with fast_get_timeoffset(),
+ * drift-proof precision TSC calibration on boot
+ * (C. Scott Ananian <cananian@alumni.princeton.edu>, Andrew D.
+ * Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
+ * ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
+ * 1998-12-16 Andrea Arcangeli
+ * Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy
+ * because was not accounting lost_ticks.
+ * 1998-12-24 Copyright (C) 1998 Andrea Arcangeli
+ * Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
+ * serialize accesses to xtime/lost_ticks).
+ */
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/module.h>
+#include <linux/sysdev.h>
+#include <linux/bcd.h>
+#include <linux/efi.h>
+#include <linux/mca.h>
+#include <linux/sysctl.h>
+#include <linux/percpu.h>
+#include <linux/kernel_stat.h>
+#include <linux/posix-timers.h>
+
+#include <asm/io.h>
+#include <asm/smp.h>
+#include <asm/irq.h>
+#include <asm/msr.h>
+#include <asm/delay.h>
+#include <asm/mpspec.h>
+#include <asm/uaccess.h>
+#include <asm/processor.h>
+#include <asm/timer.h>
+#include <asm/sections.h>
+
+#include "mach_time.h"
+
+#include <linux/timex.h>
+#include <linux/config.h>
+
+#include <asm/hpet.h>
+
+#include <asm/arch_hooks.h>
+
+#include <xen/evtchn.h>
+#include <xen/interface/vcpu.h>
+
+#if defined (__i386__)
+#include <asm/i8259.h>
+#endif
+
+int pit_latch_buggy; /* extern */
+
+#if defined(__x86_64__)
+unsigned long vxtime_hz = PIT_TICK_RATE;
+struct vxtime_data __vxtime __section_vxtime; /* for vsyscalls */
+volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;
+unsigned long __wall_jiffies __section_wall_jiffies = INITIAL_JIFFIES;
+struct timespec __xtime __section_xtime;
+struct timezone __sys_tz __section_sys_tz;
+#endif
+
+unsigned int cpu_khz; /* Detected as we calibrate the TSC */
+EXPORT_SYMBOL(cpu_khz);
+
+extern unsigned long wall_jiffies;
+
+DEFINE_SPINLOCK(rtc_lock);
+EXPORT_SYMBOL(rtc_lock);
+
+#if defined (__i386__)
+#include <asm/i8253.h>
+#endif
+
+DEFINE_SPINLOCK(i8253_lock);
+EXPORT_SYMBOL(i8253_lock);
+
+extern struct init_timer_opts timer_tsc_init;
+extern struct timer_opts timer_tsc;
+#define timer_none timer_tsc
+struct timer_opts *cur_timer __read_mostly = &timer_tsc;
+
+/* These are peridically updated in shared_info, and then copied here. */
+struct shadow_time_info {
+ u64 tsc_timestamp; /* TSC at last update of time vals. */
+ u64 system_timestamp; /* Time, in nanosecs, since boot. */
+ u32 tsc_to_nsec_mul;
+ u32 tsc_to_usec_mul;
+ int tsc_shift;
+ u32 version;
+};
+static DEFINE_PER_CPU(struct shadow_time_info, shadow_time);
+static struct timespec shadow_tv;
+static u32 shadow_tv_version;
+
+/* Keep track of last time we did processing/updating of jiffies and xtime. */
+static u64 processed_system_time; /* System time (ns) at last processing. */
+static DEFINE_PER_CPU(u64, processed_system_time);
+
+/* How much CPU time was spent blocked and how much was 'stolen'? */
+static DEFINE_PER_CPU(u64, processed_stolen_time);
+static DEFINE_PER_CPU(u64, processed_blocked_time);
+
+/* Current runstate of each CPU (updated automatically by the hypervisor). */
+static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
+
+/* Must be signed, as it's compared with s64 quantities which can be -ve. */
+#define NS_PER_TICK (1000000000LL/HZ)
+
+static inline void __normalize_time(time_t *sec, s64 *nsec)
+{
+ while (*nsec >= NSEC_PER_SEC) {
+ (*nsec) -= NSEC_PER_SEC;
+ (*sec)++;
+ }
+ while (*nsec < 0) {
+ (*nsec) += NSEC_PER_SEC;
+ (*sec)--;
+ }
+}
+
+/* Does this guest OS track Xen time, or set its wall clock independently? */
+static int independent_wallclock = 0;
+static int __init __independent_wallclock(char *str)
+{
+ independent_wallclock = 1;
+ return 1;
+}
+__setup("independent_wallclock", __independent_wallclock);
+
+/* Permitted clock jitter, in nsecs, beyond which a warning will be printed. */
+static unsigned long permitted_clock_jitter = 10000000UL; /* 10ms */
+static int __init __permitted_clock_jitter(char *str)
+{
+ permitted_clock_jitter = simple_strtoul(str, NULL, 0);
+ return 1;
+}
+__setup("permitted_clock_jitter=", __permitted_clock_jitter);
+
+int tsc_disable __devinitdata = 0;
+
+static void delay_tsc(unsigned long loops)
+{
+ unsigned long bclock, now;
+
+ rdtscl(bclock);
+ do {
+ rep_nop();
+ rdtscl(now);
+ } while ((now - bclock) < loops);
+}
+
+struct timer_opts timer_tsc = {
+ .name = "tsc",
+ .delay = delay_tsc,
+};
+
+/*
+ * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
+ * yielding a 64-bit result.
+ */
+static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift)
+{
+ u64 product;
+#ifdef __i386__
+ u32 tmp1, tmp2;
+#endif
+
+ if (shift < 0)
+ delta >>= -shift;
+ else
+ delta <<= shift;
+
+#ifdef __i386__
+ __asm__ (
+ "mul %5 ; "
+ "mov %4,%%eax ; "
+ "mov %%edx,%4 ; "
+ "mul %5 ; "
+ "xor %5,%5 ; "
+ "add %4,%%eax ; "
+ "adc %5,%%edx ; "
+ : "=A" (product), "=r" (tmp1), "=r" (tmp2)
+ : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
+#else
+ __asm__ (
+ "mul %%rdx ; shrd $32,%%rdx,%%rax"
+ : "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
+#endif
+
+ return product;
+}
+
+#if defined (__i386__)
+int read_current_timer(unsigned long *timer_val)
+{
+ rdtscl(*timer_val);
+ return 0;
+}
+#endif
+
+void init_cpu_khz(void)
+{
+ u64 __cpu_khz = 1000000ULL << 32;
+ struct vcpu_time_info *info;
+ info = &HYPERVISOR_shared_info->vcpu_info[0].time;
+ do_div(__cpu_khz, info->tsc_to_system_mul);
+ if (info->tsc_shift < 0)
+ cpu_khz = __cpu_khz << -info->tsc_shift;
+ else
+ cpu_khz = __cpu_khz >> info->tsc_shift;
+}
+
+static u64 get_nsec_offset(struct shadow_time_info *shadow)
+{
+ u64 now, delta;
+ rdtscll(now);
+ delta = now - shadow->tsc_timestamp;
+ return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift);
+}
+
+static unsigned long get_usec_offset(struct shadow_time_info *shadow)
+{
+ u64 now, delta;
+ rdtscll(now);
+ delta = now - shadow->tsc_timestamp;
+ return scale_delta(delta, shadow->tsc_to_usec_mul, shadow->tsc_shift);
+}
+
+static void __update_wallclock(time_t sec, long nsec)
+{
+ long wtm_nsec, xtime_nsec;
+ time_t wtm_sec, xtime_sec;
+ u64 tmp, wc_nsec;
+
+ /* Adjust wall-clock time base based on wall_jiffies ticks. */
+ wc_nsec = processed_system_time;
+ wc_nsec += sec * (u64)NSEC_PER_SEC;
+ wc_nsec += nsec;
+ wc_nsec -= (jiffies - wall_jiffies) * (u64)NS_PER_TICK;
+
+ /* Split wallclock base into seconds and nanoseconds. */
+ tmp = wc_nsec;
+ xtime_nsec = do_div(tmp, 1000000000);
+ xtime_sec = (time_t)tmp;
+
+ wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - xtime_sec);
+ wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - xtime_nsec);
+
+ set_normalized_timespec(&xtime, xtime_sec, xtime_nsec);
+ set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
+
+ ntp_clear();
+}
+
+static void update_wallclock(void)
+{
+ struct shared_info *s = HYPERVISOR_shared_info;
+
+ do {
+ shadow_tv_version = s->wc_version;
+ rmb();
+ shadow_tv.tv_sec = s->wc_sec;
+ shadow_tv.tv_nsec = s->wc_nsec;
+ rmb();
+ } while ((s->wc_version & 1) | (shadow_tv_version ^ s->wc_version));
+
+ if (!independent_wallclock)
+ __update_wallclock(shadow_tv.tv_sec, shadow_tv.tv_nsec);
+}
+
+/*
+ * Reads a consistent set of time-base values from Xen, into a shadow data
+ * area.
+ */
+static void get_time_values_from_xen(void)
+{
+ struct shared_info *s = HYPERVISOR_shared_info;
+ struct vcpu_time_info *src;
+ struct shadow_time_info *dst;
+
+ src = &s->vcpu_info[smp_processor_id()].time;
+ dst = &per_cpu(shadow_time, smp_processor_id());
+
+ do {
+ dst->version = src->version;
+ rmb();
+ dst->tsc_timestamp = src->tsc_timestamp;
+ dst->system_timestamp = src->system_time;
+ dst->tsc_to_nsec_mul = src->tsc_to_system_mul;
+ dst->tsc_shift = src->tsc_shift;
+ rmb();
+ } while ((src->version & 1) | (dst->version ^ src->version));
+
+ dst->tsc_to_usec_mul = dst->tsc_to_nsec_mul / 1000;
+}
+
+static inline int time_values_up_to_date(int cpu)
+{
+ struct vcpu_time_info *src;
+ struct shadow_time_info *dst;
+
+ src = &HYPERVISOR_shared_info->vcpu_info[cpu].time;
+ dst = &per_cpu(shadow_time, cpu);
+
+ rmb();
+ return (dst->version == src->version);
+}
+
+/*
+ * This is a special lock that is owned by the CPU and holds the index
+ * register we are working with. It is required for NMI access to the
+ * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
+ */
+volatile unsigned long cmos_lock = 0;
+EXPORT_SYMBOL(cmos_lock);
+
+/* Routines for accessing the CMOS RAM/RTC. */
+unsigned char rtc_cmos_read(unsigned char addr)
+{
+ unsigned char val;
+ lock_cmos_prefix(addr);
+ outb_p(addr, RTC_PORT(0));
+ val = inb_p(RTC_PORT(1));
+ lock_cmos_suffix(addr);
+ return val;
+}
+EXPORT_SYMBOL(rtc_cmos_read);
+
+void rtc_cmos_write(unsigned char val, unsigned char addr)
+{
+ lock_cmos_prefix(addr);
+ outb_p(addr, RTC_PORT(0));
+ outb_p(val, RTC_PORT(1));
+ lock_cmos_suffix(addr);
+}
+EXPORT_SYMBOL(rtc_cmos_write);
+
+/*
+ * This version of gettimeofday has microsecond resolution
+ * and better than microsecond precision on fast x86 machines with TSC.
+ */
+void do_gettimeofday(struct timeval *tv)
+{
+ unsigned long seq;
+ unsigned long usec, sec;
+ unsigned long max_ntp_tick;
+ s64 nsec;
+ unsigned int cpu;
+ struct shadow_time_info *shadow;
+ u32 local_time_version;
+
+ cpu = get_cpu();
+ shadow = &per_cpu(shadow_time, cpu);
+
+ do {
+ unsigned long lost;
+
+ local_time_version = shadow->version;
+ seq = read_seqbegin(&xtime_lock);
+
+ usec = get_usec_offset(shadow);
+ lost = jiffies - wall_jiffies;
+
+ /*
+ * If time_adjust is negative then NTP is slowing the clock
+ * so make sure not to go into next possible interval.
+ * Better to lose some accuracy than have time go backwards..
+ */
+ if (unlikely(time_adjust < 0)) {
+ max_ntp_tick = (USEC_PER_SEC / HZ) - tickadj;
+ usec = min(usec, max_ntp_tick);
+
+ if (lost)
+ usec += lost * max_ntp_tick;
+ }
+ else if (unlikely(lost))
+ usec += lost * (USEC_PER_SEC / HZ);
+
+ sec = xtime.tv_sec;
+ usec += (xtime.tv_nsec / NSEC_PER_USEC);
+
+ nsec = shadow->system_timestamp - processed_system_time;
+ __normalize_time(&sec, &nsec);
+ usec += (long)nsec / NSEC_PER_USEC;
+
+ if (unlikely(!time_values_up_to_date(cpu))) {
+ /*
+ * We may have blocked for a long time,
+ * rendering our calculations invalid
+ * (e.g. the time delta may have
+ * overflowed). Detect that and recalculate
+ * with fresh values.
+ */
+ get_time_values_from_xen();
+ continue;
+ }
+ } while (read_seqretry(&xtime_lock, seq) ||
+ (local_time_version != shadow->version));
+
+ put_cpu();
+
+ while (usec >= USEC_PER_SEC) {
+ usec -= USEC_PER_SEC;
+ sec++;
+ }
+
+ tv->tv_sec = sec;
+ tv->tv_usec = usec;
+}
+
+EXPORT_SYMBOL(do_gettimeofday);
+
+int do_settimeofday(struct timespec *tv)
+{
+ time_t sec;
+ s64 nsec;
+ unsigned int cpu;
+ struct shadow_time_info *shadow;
+
+ if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
+ return -EINVAL;
+
+ cpu = get_cpu();
+ shadow = &per_cpu(shadow_time, cpu);
+
+ write_seqlock_irq(&xtime_lock);
+
+ /*
+ * Ensure we don't get blocked for a long time so that our time delta
+ * overflows. If that were to happen then our shadow time values would
+ * be stale, so we can retry with fresh ones.
+ */
+ for (;;) {
+ nsec = tv->tv_nsec - get_nsec_offset(shadow);
+ if (time_values_up_to_date(cpu))
+ break;
+ get_time_values_from_xen();
+ }
+ sec = tv->tv_sec;
+ __normalize_time(&sec, &nsec);
+
+ if (independent_wallclock) {
+ nsec -= shadow->system_timestamp;
+ __normalize_time(&sec, &nsec);
+ __update_wallclock(sec, nsec);
+ }
+
+ write_sequnlock_irq(&xtime_lock);
+
+ put_cpu();
+
+ clock_was_set();
+ return 0;
+}
+
+EXPORT_SYMBOL(do_settimeofday);
+
+static int set_rtc_mmss(unsigned long nowtime)
+{
+ int retval;
+
+ WARN_ON(irqs_disabled());
+
+ if (independent_wallclock || !(xen_start_info->flags & SIF_INITDOMAIN))
+ return 0;
+
+ /* gets recalled with irq locally disabled */
+ spin_lock_irq(&rtc_lock);
+ if (efi_enabled)
+ retval = efi_set_rtc_mmss(nowtime);
+ else
+ retval = mach_set_rtc_mmss(nowtime);
+ spin_unlock_irq(&rtc_lock);
+
+ return retval;
+}
+
+/* monotonic_clock(): returns # of nanoseconds passed since time_init()
+ * Note: This function is required to return accurate
+ * time even in the absence of multiple timer ticks.
+ */
+unsigned long long monotonic_clock(void)
+{
+ int cpu = get_cpu();
+ struct shadow_time_info *shadow = &per_cpu(shadow_time, cpu);
+ u64 time;
+ u32 local_time_version;
+
+ do {
+ local_time_version = shadow->version;
+ barrier();
+ time = shadow->system_timestamp + get_nsec_offset(shadow);
+ if (!time_values_up_to_date(cpu))
+ get_time_values_from_xen();
+ barrier();
+ } while (local_time_version != shadow->version);
+
+ put_cpu();
+
+ return time;
+}
+EXPORT_SYMBOL(monotonic_clock);
+
+unsigned long long sched_clock(void)
+{
+ return monotonic_clock();
+}
+
+#if defined(CONFIG_SMP) && defined(CONFIG_FRAME_POINTER)
+unsigned long profile_pc(struct pt_regs *regs)
+{
+ unsigned long pc = instruction_pointer(regs);
+
+#ifdef __x86_64__
+ /* Assume the lock function has either no stack frame or only a single word.
+ This checks if the address on the stack looks like a kernel text address.
+ There is a small window for false hits, but in that case the tick
+ is just accounted to the spinlock function.
+ Better would be to write these functions in assembler again
+ and check exactly. */
+ if (in_lock_functions(pc)) {
+ char *v = *(char **)regs->rsp;
+ if ((v >= _stext && v <= _etext) ||
+ (v >= _sinittext && v <= _einittext) ||
+ (v >= (char *)MODULES_VADDR && v <= (char *)MODULES_END))
+ return (unsigned long)v;
+ return ((unsigned long *)regs->rsp)[1];
+ }
+#else
+ if (in_lock_functions(pc))
+ return *(unsigned long *)(regs->ebp + 4);
+#endif
+
+ return pc;
+}
+EXPORT_SYMBOL(profile_pc);
+#endif
+
+irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ s64 delta, delta_cpu, stolen, blocked;
+ u64 sched_time;
+ int i, cpu = smp_processor_id();
+ struct shadow_time_info *shadow = &per_cpu(shadow_time, cpu);
+ struct vcpu_runstate_info *runstate = &per_cpu(runstate, cpu);
+
+ write_seqlock(&xtime_lock);
+
+ do {
+ get_time_values_from_xen();
+
+ /* Obtain a consistent snapshot of elapsed wallclock cycles. */
+ delta = delta_cpu =
+ shadow->system_timestamp + get_nsec_offset(shadow);
+ delta -= processed_system_time;
+ delta_cpu -= per_cpu(processed_system_time, cpu);
+
+ /*
+ * Obtain a consistent snapshot of stolen/blocked cycles. We
+ * can use state_entry_time to detect if we get preempted here.
+ */
+ do {
+ sched_time = runstate->state_entry_time;
+ barrier();
+ stolen = runstate->time[RUNSTATE_runnable] +
+ runstate->time[RUNSTATE_offline] -
+ per_cpu(processed_stolen_time, cpu);
+ blocked = runstate->time[RUNSTATE_blocked] -
+ per_cpu(processed_blocked_time, cpu);
+ barrier();
+ } while (sched_time != runstate->state_entry_time);
+ } while (!time_values_up_to_date(cpu));
+
+ if ((unlikely(delta < -(s64)permitted_clock_jitter) ||
+ unlikely(delta_cpu < -(s64)permitted_clock_jitter))
+ && printk_ratelimit()) {
+ printk("Timer ISR/%d: Time went backwards: "
+ "delta=%lld delta_cpu=%lld shadow=%lld "
+ "off=%lld processed=%lld cpu_processed=%lld\n",
+ cpu, delta, delta_cpu, shadow->system_timestamp,
+ (s64)get_nsec_offset(shadow),
+ processed_system_time,
+ per_cpu(processed_system_time, cpu));
+ for (i = 0; i < num_online_cpus(); i++)
+ printk(" %d: %lld\n", i,
+ per_cpu(processed_system_time, i));
+ }
+
+ /* System-wide jiffy work. */
+ while (delta >= NS_PER_TICK) {
+ delta -= NS_PER_TICK;
+ processed_system_time += NS_PER_TICK;
+ do_timer(regs);
+ }
+
+ if (shadow_tv_version != HYPERVISOR_shared_info->wc_version) {
+ update_wallclock();
+ clock_was_set();
+ }
+
+ write_sequnlock(&xtime_lock);
+
+ /*
+ * Account stolen ticks.
+ * HACK: Passing NULL to account_steal_time()
+ * ensures that the ticks are accounted as stolen.
+ */
+ if ((stolen > 0) && (delta_cpu > 0)) {
+ delta_cpu -= stolen;
+ if (unlikely(delta_cpu < 0))
+ stolen += delta_cpu; /* clamp local-time progress */
+ do_div(stolen, NS_PER_TICK);
+ per_cpu(processed_stolen_time, cpu) += stolen * NS_PER_TICK;
+ per_cpu(processed_system_time, cpu) += stolen * NS_PER_TICK;
+ account_steal_time(NULL, (cputime_t)stolen);
+ }
+
+ /*
+ * Account blocked ticks.
+ * HACK: Passing idle_task to account_steal_time()
+ * ensures that the ticks are accounted as idle/wait.
+ */
+ if ((blocked > 0) && (delta_cpu > 0)) {
+ delta_cpu -= blocked;
+ if (unlikely(delta_cpu < 0))
+ blocked += delta_cpu; /* clamp local-time progress */
+ do_div(blocked, NS_PER_TICK);
+ per_cpu(processed_blocked_time, cpu) += blocked * NS_PER_TICK;
+ per_cpu(processed_system_time, cpu) += blocked * NS_PER_TICK;
+ account_steal_time(idle_task(cpu), (cputime_t)blocked);
+ }
+
+ /* Account user/system ticks. */
+ if (delta_cpu > 0) {
+ do_div(delta_cpu, NS_PER_TICK);
+ per_cpu(processed_system_time, cpu) += delta_cpu * NS_PER_TICK;
+ if (user_mode(regs))
+ account_user_time(current, (cputime_t)delta_cpu);
+ else
+ account_system_time(current, HARDIRQ_OFFSET,
+ (cputime_t)delta_cpu);
+ }
+
+ /* Local timer processing (see update_process_times()). */
+ run_local_timers();
+ if (rcu_pending(cpu))
+ rcu_check_callbacks(cpu, user_mode(regs));
+ scheduler_tick();
+ run_posix_cpu_timers(current);
+
+ return IRQ_HANDLED;
+}
+
+static void init_missing_ticks_accounting(int cpu)
+{
+ struct vcpu_register_runstate_memory_area area;
+ struct vcpu_runstate_info *runstate = &per_cpu(runstate, cpu);
+
+ memset(runstate, 0, sizeof(*runstate));
+
+ area.addr.v = runstate;
+ HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, cpu, &area);
+
+ per_cpu(processed_blocked_time, cpu) =
+ runstate->time[RUNSTATE_blocked];
+ per_cpu(processed_stolen_time, cpu) =
+ runstate->time[RUNSTATE_runnable] +
+ runstate->time[RUNSTATE_offline];
+}
+
+/* not static: needed by APM */
+unsigned long get_cmos_time(void)
+{
+ unsigned long retval;
+
+ spin_lock(&rtc_lock);
+
+ if (efi_enabled)
+ retval = efi_get_time();
+ else
+ retval = mach_get_cmos_time();
+
+ spin_unlock(&rtc_lock);
+
+ return retval;
+}
+EXPORT_SYMBOL(get_cmos_time);
+
+static void sync_cmos_clock(unsigned long dummy);
+
+static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
+
+static void sync_cmos_clock(unsigned long dummy)
+{
+ struct timeval now, next;
+ int fail = 1;
+
+ /*
+ * If we have an externally synchronized Linux clock, then update
+ * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
+ * called as close as possible to 500 ms before the new second starts.
+ * This code is run on a timer. If the clock is set, that timer
+ * may not expire at the correct time. Thus, we adjust...
+ */
+ if (!ntp_synced())
+ /*
+ * Not synced, exit, do not restart a timer (if one is
+ * running, let it run out).
+ */
+ return;
+
+ do_gettimeofday(&now);
+ if (now.tv_usec >= USEC_AFTER - ((unsigned) TICK_SIZE) / 2 &&
+ now.tv_usec <= USEC_BEFORE + ((unsigned) TICK_SIZE) / 2)
+ fail = set_rtc_mmss(now.tv_sec);
+
+ next.tv_usec = USEC_AFTER - now.tv_usec;
+ if (next.tv_usec <= 0)
+ next.tv_usec += USEC_PER_SEC;
+
+ if (!fail)
+ next.tv_sec = 659;
+ else
+ next.tv_sec = 0;
+
+ if (next.tv_usec >= USEC_PER_SEC) {
+ next.tv_sec++;
+ next.tv_usec -= USEC_PER_SEC;
+ }
+ mod_timer(&sync_cmos_timer, jiffies + timeval_to_jiffies(&next));
+}
+
+void notify_arch_cmos_timer(void)
+{
+ mod_timer(&sync_cmos_timer, jiffies + 1);
+}
+
+static long clock_cmos_diff, sleep_start;
+
+static struct timer_opts *last_timer;
+static int timer_suspend(struct sys_device *dev, pm_message_t state)
+{
+ /*
+ * Estimate time zone so that set_time can update the clock
+ */
+ clock_cmos_diff = -get_cmos_time();
+ clock_cmos_diff += get_seconds();
+ sleep_start = get_cmos_time();
+ last_timer = cur_timer;
+ cur_timer = &timer_none;
+ if (last_timer->suspend)
+ last_timer->suspend(state);
+ return 0;
+}
+
+static int timer_resume(struct sys_device *dev)
+{
+ unsigned long flags;
+ unsigned long sec;
+ unsigned long sleep_length;
+
+#ifdef CONFIG_HPET_TIMER
+ if (is_hpet_enabled())
+ hpet_reenable();
+#endif
+ sec = get_cmos_time() + clock_cmos_diff;
+ sleep_length = (get_cmos_time() - sleep_start) * HZ;
+ write_seqlock_irqsave(&xtime_lock, flags);
+ xtime.tv_sec = sec;
+ xtime.tv_nsec = 0;
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+ jiffies += sleep_length;
+ wall_jiffies += sleep_length;
+ if (last_timer->resume)
+ last_timer->resume();
+ cur_timer = last_timer;
+ last_timer = NULL;
+ touch_softlockup_watchdog();
+ return 0;
+}
+
+static struct sysdev_class timer_sysclass = {
+ .resume = timer_resume,
+ .suspend = timer_suspend,
+ set_kset_name("timer"),
+};
+
+
+/* XXX this driverfs stuff should probably go elsewhere later -john */
+static struct sys_device device_timer = {
+ .id = 0,
+ .cls = &timer_sysclass,
+};
+
+static int time_init_device(void)
+{
+ int error = sysdev_class_register(&timer_sysclass);
+ if (!error)
+ error = sysdev_register(&device_timer);
+ return error;
+}
+
+device_initcall(time_init_device);
+
+#ifdef CONFIG_HPET_TIMER
+extern void (*late_time_init)(void);
+/* Duplicate of time_init() below, with hpet_enable part added */
+static void __init hpet_time_init(void)
+{
+ xtime.tv_sec = get_cmos_time();
+ xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
+ set_normalized_timespec(&wall_to_monotonic,
+ -xtime.tv_sec, -xtime.tv_nsec);
+
+ if ((hpet_enable() >= 0) && hpet_use_timer) {
+ printk("Using HPET for base-timer\n");
+ }
+
+ cur_timer = select_timer();
+ printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);
+
+ time_init_hook();
+}
+#endif
+
+/* Dynamically-mapped IRQ. */
+DEFINE_PER_CPU(int, timer_irq);
+
+extern void (*late_time_init)(void);
+static void setup_cpu0_timer_irq(void)
+{
+ per_cpu(timer_irq, 0) =
+ bind_virq_to_irqhandler(
+ VIRQ_TIMER,
+ 0,
+ timer_interrupt,
+ SA_INTERRUPT,
+ "timer0",
+ NULL);
+ BUG_ON(per_cpu(timer_irq, 0) < 0);
+}
+
+void __init time_init(void)
+{
+#ifdef CONFIG_HPET_TIMER
+ if (is_hpet_capable()) {
+ /*
+ * HPET initialization needs to do memory-mapped io. So, let
+ * us do a late initialization after mem_init().
+ */
+ late_time_init = hpet_time_init;
+ return;
+ }
+#endif
+ get_time_values_from_xen();
+
+ processed_system_time = per_cpu(shadow_time, 0).system_timestamp;
+ per_cpu(processed_system_time, 0) = processed_system_time;
+ init_missing_ticks_accounting(0);
+
+ update_wallclock();
+
+ init_cpu_khz();
+ printk(KERN_INFO "Xen reported: %u.%03u MHz processor.\n",
+ cpu_khz / 1000, cpu_khz % 1000);
+
+#if defined(__x86_64__)
+ vxtime.mode = VXTIME_TSC;
+ vxtime.quot = (1000000L << 32) / vxtime_hz;
+ vxtime.tsc_quot = (1000L << 32) / cpu_khz;
+ sync_core();
+ rdtscll(vxtime.last_tsc);
+#endif
+
+ /* Cannot request_irq() until kmem is initialised. */
+ late_time_init = setup_cpu0_timer_irq;
+}
+
+/* Convert jiffies to system time. */
+u64 jiffies_to_st(unsigned long j)
+{
+ unsigned long seq;
+ long delta;
+ u64 st;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ delta = j - jiffies;
+ /* NB. The next check can trigger in some wrap-around cases,
+ * but that's ok: we'll just end up with a shorter timeout. */
+ if (delta < 1)
+ delta = 1;
+ st = processed_system_time + (delta * (u64)NS_PER_TICK);
+ } while (read_seqretry(&xtime_lock, seq));
+
+ return st;
+}
+EXPORT_SYMBOL(jiffies_to_st);
+
+/*
+ * stop_hz_timer / start_hz_timer - enter/exit 'tickless mode' on an idle cpu
+ * These functions are based on implementations from arch/s390/kernel/time.c
+ */
+void stop_hz_timer(void)
+{
+ unsigned int cpu = smp_processor_id();
+ unsigned long j;
+
+ /* We must do this /before/ checking rcu_pending(). */
+ cpu_set(cpu, nohz_cpu_mask);
+ smp_mb();
+
+ /* Leave ourselves in 'tick mode' if rcu or softirq pending. */
+ if (rcu_pending(cpu) || local_softirq_pending()) {
+ cpu_clear(cpu, nohz_cpu_mask);
+ j = jiffies + 1;
+ } else {
+ j = next_timer_interrupt();
+ }
+
+ BUG_ON(HYPERVISOR_set_timer_op(jiffies_to_st(j)) != 0);
+}
+
+void start_hz_timer(void)
+{
+ cpu_clear(smp_processor_id(), nohz_cpu_mask);
+}
+
+/* No locking required. We are only CPU running, and interrupts are off. */
+void time_resume(void)
+{
+ init_cpu_khz();
+
+ get_time_values_from_xen();
+
+ processed_system_time = per_cpu(shadow_time, 0).system_timestamp;
+ per_cpu(processed_system_time, 0) = processed_system_time;
+ init_missing_ticks_accounting(0);
+
+ update_wallclock();
+}
+
+#ifdef CONFIG_SMP
+static char timer_name[NR_CPUS][15];
+
+void local_setup_timer(unsigned int cpu)
+{
+ int seq;
+
+ BUG_ON(cpu == 0);
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ /* Use cpu0 timestamp: cpu's shadow is not initialised yet. */
+ per_cpu(processed_system_time, cpu) =
+ per_cpu(shadow_time, 0).system_timestamp;
+ init_missing_ticks_accounting(cpu);
+ } while (read_seqretry(&xtime_lock, seq));
+
+ sprintf(timer_name[cpu], "timer%d", cpu);
+ per_cpu(timer_irq, cpu) =
+ bind_virq_to_irqhandler(
+ VIRQ_TIMER,
+ cpu,
+ timer_interrupt,
+ SA_INTERRUPT,
+ timer_name[cpu],
+ NULL);
+ BUG_ON(per_cpu(timer_irq, cpu) < 0);
+}
+
+void local_teardown_timer(unsigned int cpu)
+{
+ BUG_ON(cpu == 0);
+ unbind_from_irqhandler(per_cpu(timer_irq, cpu), NULL);
+}
+#endif
+
+/*
+ * /proc/sys/xen: This really belongs in another file. It can stay here for
+ * now however.
+ */
+static ctl_table xen_subtable[] = {
+ {
+ .ctl_name = 1,
+ .procname = "independent_wallclock",
+ .data = &independent_wallclock,
+ .maxlen = sizeof(independent_wallclock),
+ .mode = 0644,
+ .proc_handler = proc_dointvec
+ },
+ {
+ .ctl_name = 2,
+ .procname = "permitted_clock_jitter",
+ .data = &permitted_clock_jitter,
+ .maxlen = sizeof(permitted_clock_jitter),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax
+ },
+ { 0 }
+};
+static ctl_table xen_table[] = {
+ {
+ .ctl_name = 123,
+ .procname = "xen",
+ .mode = 0555,
+ .child = xen_subtable},
+ { 0 }
+};
+static int __init xen_sysctl_init(void)
+{
+ (void)register_sysctl_table(xen_table, 0);
+ return 0;
+}
+__initcall(xen_sysctl_init);
--
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