x86: Make xen use the paravirt clocksource structs and functions
This patch updates the xen guest to use the pvclock structs and helper functions. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Gerd Hoffmann
Avi Kivity
parent
7af192c954
commit
1c7b67f757
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@ -5,6 +5,7 @@
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config XEN
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bool "Xen guest support"
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select PARAVIRT
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select PARAVIRT_CLOCK
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depends on X86_32
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depends on X86_CMPXCHG && X86_TSC && !(X86_VISWS || X86_VOYAGER)
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help
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@ -14,6 +14,7 @@
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#include <linux/kernel_stat.h>
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#include <linux/math64.h>
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#include <asm/pvclock.h>
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#include <asm/xen/hypervisor.h>
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#include <asm/xen/hypercall.h>
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@ -31,17 +32,6 @@
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static cycle_t xen_clocksource_read(void);
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/* These are perodically updated in shared_info, and then copied here. */
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struct shadow_time_info {
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u64 tsc_timestamp; /* TSC at last update of time vals. */
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u64 system_timestamp; /* Time, in nanosecs, since boot. */
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u32 tsc_to_nsec_mul;
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int tsc_shift;
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u32 version;
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};
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static DEFINE_PER_CPU(struct shadow_time_info, shadow_time);
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/* runstate info updated by Xen */
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static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
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@ -211,7 +201,7 @@ unsigned long long xen_sched_clock(void)
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unsigned long xen_cpu_khz(void)
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{
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u64 xen_khz = 1000000ULL << 32;
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const struct vcpu_time_info *info =
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const struct pvclock_vcpu_time_info *info =
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&HYPERVISOR_shared_info->vcpu_info[0].time;
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do_div(xen_khz, info->tsc_to_system_mul);
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@ -223,121 +213,26 @@ unsigned long xen_cpu_khz(void)
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return xen_khz;
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}
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/*
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* Reads a consistent set of time-base values from Xen, into a shadow data
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* area.
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*/
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static unsigned get_time_values_from_xen(void)
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{
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struct vcpu_time_info *src;
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struct shadow_time_info *dst;
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/* src is shared memory with the hypervisor, so we need to
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make sure we get a consistent snapshot, even in the face of
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being preempted. */
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src = &__get_cpu_var(xen_vcpu)->time;
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dst = &__get_cpu_var(shadow_time);
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do {
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dst->version = src->version;
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rmb(); /* fetch version before data */
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dst->tsc_timestamp = src->tsc_timestamp;
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dst->system_timestamp = src->system_time;
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dst->tsc_to_nsec_mul = src->tsc_to_system_mul;
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dst->tsc_shift = src->tsc_shift;
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rmb(); /* test version after fetching data */
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} while ((src->version & 1) | (dst->version ^ src->version));
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return dst->version;
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}
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/*
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* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
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* yielding a 64-bit result.
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*/
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static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift)
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{
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u64 product;
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#ifdef __i386__
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u32 tmp1, tmp2;
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#endif
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if (shift < 0)
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delta >>= -shift;
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else
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delta <<= shift;
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#ifdef __i386__
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__asm__ (
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"mul %5 ; "
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"mov %4,%%eax ; "
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"mov %%edx,%4 ; "
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"mul %5 ; "
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"xor %5,%5 ; "
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"add %4,%%eax ; "
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"adc %5,%%edx ; "
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: "=A" (product), "=r" (tmp1), "=r" (tmp2)
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: "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
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#elif __x86_64__
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__asm__ (
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"mul %%rdx ; shrd $32,%%rdx,%%rax"
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: "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
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#else
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#error implement me!
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#endif
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return product;
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}
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static u64 get_nsec_offset(struct shadow_time_info *shadow)
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{
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u64 now, delta;
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now = native_read_tsc();
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delta = now - shadow->tsc_timestamp;
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return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift);
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}
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static cycle_t xen_clocksource_read(void)
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{
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struct shadow_time_info *shadow = &get_cpu_var(shadow_time);
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struct pvclock_vcpu_time_info *src;
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cycle_t ret;
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unsigned version;
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do {
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version = get_time_values_from_xen();
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barrier();
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ret = shadow->system_timestamp + get_nsec_offset(shadow);
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barrier();
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} while (version != __get_cpu_var(xen_vcpu)->time.version);
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put_cpu_var(shadow_time);
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src = &get_cpu_var(xen_vcpu)->time;
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ret = pvclock_clocksource_read(src);
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put_cpu_var(xen_vcpu);
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return ret;
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}
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static void xen_read_wallclock(struct timespec *ts)
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{
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const struct shared_info *s = HYPERVISOR_shared_info;
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u32 version;
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u64 delta;
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struct timespec now;
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struct shared_info *s = HYPERVISOR_shared_info;
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struct pvclock_wall_clock *wall_clock = &(s->wc);
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struct pvclock_vcpu_time_info *vcpu_time;
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/* get wallclock at system boot */
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do {
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version = s->wc_version;
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rmb(); /* fetch version before time */
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now.tv_sec = s->wc_sec;
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now.tv_nsec = s->wc_nsec;
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rmb(); /* fetch time before checking version */
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} while ((s->wc_version & 1) | (version ^ s->wc_version));
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delta = xen_clocksource_read(); /* time since system boot */
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delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec;
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now.tv_nsec = do_div(delta, NSEC_PER_SEC);
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now.tv_sec = delta;
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set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
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vcpu_time = &get_cpu_var(xen_vcpu)->time;
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pvclock_read_wallclock(wall_clock, vcpu_time, ts);
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put_cpu_var(xen_vcpu);
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}
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unsigned long xen_get_wallclock(void)
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@ -345,7 +240,6 @@ unsigned long xen_get_wallclock(void)
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struct timespec ts;
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xen_read_wallclock(&ts);
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return ts.tv_sec;
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}
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@ -569,8 +463,6 @@ __init void xen_time_init(void)
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{
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int cpu = smp_processor_id();
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get_time_values_from_xen();
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clocksource_register(&xen_clocksource);
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if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) {
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@ -10,6 +10,7 @@
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#define __XEN_PUBLIC_XEN_H__
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#include <asm/xen/interface.h>
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#include <asm/pvclock-abi.h>
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/*
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* XEN "SYSTEM CALLS" (a.k.a. HYPERCALLS).
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@ -336,7 +337,7 @@ struct vcpu_info {
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uint8_t evtchn_upcall_mask;
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unsigned long evtchn_pending_sel;
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struct arch_vcpu_info arch;
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struct vcpu_time_info time;
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struct pvclock_vcpu_time_info time;
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}; /* 64 bytes (x86) */
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/*
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@ -384,9 +385,7 @@ struct shared_info {
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* Wallclock time: updated only by control software. Guests should base
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* their gettimeofday() syscall on this wallclock-base value.
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*/
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uint32_t wc_version; /* Version counter: see vcpu_time_info_t. */
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uint32_t wc_sec; /* Secs 00:00:00 UTC, Jan 1, 1970. */
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uint32_t wc_nsec; /* Nsecs 00:00:00 UTC, Jan 1, 1970. */
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struct pvclock_wall_clock wc;
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struct arch_shared_info arch;
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