MFC: r285839

o Revert the other functional half of r239864, i. e. the merge of r134227
  from x86 to use smp_ipi_mtx spin lock not only for smp_rendezvous_cpus()
  but also for the MD cache invalidation, TLB demapping and remote register
  reading IPIs due to the following reasons:
  - The cross-IPI SMP deadlock x86 otherwise is subject to can't happen on
    sparc64. That's because on sparc64, spin locks don't disable interrupts
    completely but only raise the processor interrupt level to PIL_TICK. This
    means that IPIs still get delivered and direct dispatch IPIs such as the
    cache invalidation etc. IPIs in question are still executed.
  - In smp_rendezvous_cpus(), smp_ipi_mtx is held not only while sending an
    IPI_RENDEZVOUS, but until all CPUs have processed smp_rendezvous_action().
    Consequently, smp_ipi_mtx may be locked for an extended amount of time as
    queued IPIs (as opposed to the direct ones) such as IPI_RENDEZVOUS are
    scheduled via a soft interrupt. Moreover, given that this soft interrupt
    is only delivered at PIL_RENDEZVOUS, processing of smp_rendezvous_action()
    on a target may be interrupted by f. e. a tick interrupt at PIL_TICK, in
    turn leading to the target in question trying to send an IPI by itself
    while IPI_RENDEZVOUS isn't fully handled, yet, and, thus, resulting in a
    deadlock.
o As mentioned in the commit message of r245850, on least some sun4u platforms
  concurrent sending of IPIs by different CPUs is fatal. Therefore, hold the
  reintroduced MD ipi_mtx also while delivering cross-traps via MI helpers,
  i. e. ipi_{all_but_self,cpu,selected}().
o Akin to x86, let the last CPU to process cpu_mp_bootstrap() set smp_started
  instead of the BSP in cpu_mp_unleash(). This ensures that all APs actually
  are started, when smp_started is no longer 0.
o In all MD and MI IPI helpers, check for smp_started == 1 rather than for
  smp_cpus > 1 or nothing at all. This avoids races during boot causing IPIs
  trying to be delivered to APs that in fact aren't up and running, yet.
  While at it, move setting of the cpu_ipi_{selected,single}() pointers to
  the appropriate delivery functions from mp_init() to cpu_mp_start() where
  it's better suited and allows to get rid of the global isjbus variable.
o Given that now concurrent IPI delivery no longer is possible, also nuke
  the delays before completely disabling interrupts again in the CPU-specific
  cross-trap delivery functions, previously giving other CPUs a window for
  sending IPIs on their part. Actually, we now should be able to entirely get
  rid of completely disabling interrupts in these functions. Such a change
  needs more testing, though.
o In {s,}tick_get_timecount_mp(), make the {s,}tick variable static. While not
  necessary for correctness, this avoids page faults when accessing the stack
  of a foreign CPU as {s,}tick now is locked into the TLBs as part of static
  kernel data. Hence, {s,}tick_get_timecount_mp() always execute as fast as
  possible, avoiding jitter.

PR:		201245

5 files changed, 81 insertions, 80 deletions

diff --git a/sys/kern/subr_witness.c b/sys/kern/subr_witness.c
index 8b1e3a0..122a246 100644
--- a/sys/kern/subr_witness.c
+++ b/sys/kern/subr_witness.c
@@ -666,6 +666,9 @@ static struct witness_order_list_entry order_lists[] = {
 	 */
 	{ "intrcnt", &lock_class_mtx_spin },
 	{ "icu", &lock_class_mtx_spin },
+#if defined(SMP) && defined(__sparc64__)
+	{ "ipi", &lock_class_mtx_spin },
+#endif
 #ifdef __i386__
 	{ "allpmaps", &lock_class_mtx_spin },
 	{ "descriptor tables", &lock_class_mtx_spin },
diff --git a/sys/sparc64/include/smp.h b/sys/sparc64/include/smp.h
index 2e1110b..c46c4f8 100644
--- a/sys/sparc64/include/smp.h
+++ b/sys/sparc64/include/smp.h
@@ -39,13 +39,15 @@
 
 #ifndef	LOCORE
 
+#include <sys/param.h>
 #include <sys/cpuset.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/sched.h>
 #include <sys/smp.h>
 
 #include <machine/intr_machdep.h>
-#include <machine/pcb.h>
 #include <machine/tte.h>
 
 #define	IDR_BUSY			0x0000000000000001ULL
@@ -96,6 +98,7 @@ struct ipi_tlb_args {
 };
 #define	ita_va	ita_start
 
+struct pcb;
 struct pcpu;
 
 extern struct pcb stoppcbs[];
@@ -108,8 +111,9 @@ extern	cpu_ipi_selected_t *cpu_ipi_selected;
 typedef	void cpu_ipi_single_t(u_int, u_long, u_long, u_long);
 extern	cpu_ipi_single_t *cpu_ipi_single;
 
-void	mp_init(u_int cpu_impl);
+void	mp_init(void);
 
+extern	struct mtx ipi_mtx;
 extern	struct ipi_cache_args ipi_cache_args;
 extern	struct ipi_rd_args ipi_rd_args;
 extern	struct ipi_tlb_args ipi_tlb_args;
@@ -139,23 +143,37 @@ ipi_all_but_self(u_int ipi)
 {
 	cpuset_t cpus;
 
+	if (__predict_false(smp_started == 0))
+		return;
 	cpus = all_cpus;
+	sched_pin();
 	CPU_CLR(PCPU_GET(cpuid), &cpus);
+	mtx_lock_spin(&ipi_mtx);
 	cpu_ipi_selected(cpus, 0, (u_long)tl_ipi_level, ipi);
+	mtx_unlock_spin(&ipi_mtx);
+	sched_unpin();
 }
 
 static __inline void
 ipi_selected(cpuset_t cpus, u_int ipi)
 {
 
+	if (__predict_false(smp_started == 0 || CPU_EMPTY(&cpus)))
+		return;
+	mtx_lock_spin(&ipi_mtx);
 	cpu_ipi_selected(cpus, 0, (u_long)tl_ipi_level, ipi);
+	mtx_unlock_spin(&ipi_mtx);
 }
 
 static __inline void
 ipi_cpu(int cpu, u_int ipi)
 {
 
+	if (__predict_false(smp_started == 0))
+		return;
+	mtx_lock_spin(&ipi_mtx);
 	cpu_ipi_single(cpu, 0, (u_long)tl_ipi_level, ipi);
+	mtx_unlock_spin(&ipi_mtx);
 }
 
 #if defined(_MACHINE_PMAP_H_) && defined(_SYS_MUTEX_H_)
@@ -165,11 +183,11 @@ ipi_dcache_page_inval(void *func, vm_paddr_t pa)
 {
 	struct ipi_cache_args *ica;
 
-	if (smp_cpus == 1)
+	if (__predict_false(smp_started == 0))
 		return (NULL);
 	sched_pin();
 	ica = &ipi_cache_args;
-	mtx_lock_spin(&smp_ipi_mtx);
+	mtx_lock_spin(&ipi_mtx);
 	ica->ica_mask = all_cpus;
 	CPU_CLR(PCPU_GET(cpuid), &ica->ica_mask);
 	ica->ica_pa = pa;
@@ -182,11 +200,11 @@ ipi_icache_page_inval(void *func, vm_paddr_t pa)
 {
 	struct ipi_cache_args *ica;
 
-	if (smp_cpus == 1)
+	if (__predict_false(smp_started == 0))
 		return (NULL);
 	sched_pin();
 	ica = &ipi_cache_args;
-	mtx_lock_spin(&smp_ipi_mtx);
+	mtx_lock_spin(&ipi_mtx);
 	ica->ica_mask = all_cpus;
 	CPU_CLR(PCPU_GET(cpuid), &ica->ica_mask);
 	ica->ica_pa = pa;
@@ -199,11 +217,11 @@ ipi_rd(u_int cpu, void *func, u_long *val)
 {
 	struct ipi_rd_args *ira;
 
-	if (smp_cpus == 1)
+	if (__predict_false(smp_started == 0))
 		return (NULL);
 	sched_pin();
 	ira = &ipi_rd_args;
-	mtx_lock_spin(&smp_ipi_mtx);
+	mtx_lock_spin(&ipi_mtx);
 	CPU_SETOF(cpu, &ira->ira_mask);
 	ira->ira_val = val;
 	cpu_ipi_single(cpu, 0, (u_long)func, (u_long)ira);
@@ -216,7 +234,7 @@ ipi_tlb_context_demap(struct pmap *pm)
 	struct ipi_tlb_args *ita;
 	cpuset_t cpus;
 
-	if (smp_cpus == 1)
+	if (__predict_false(smp_started == 0))
 		return (NULL);
 	sched_pin();
 	cpus = pm->pm_active;
@@ -227,7 +245,7 @@ ipi_tlb_context_demap(struct pmap *pm)
 		return (NULL);
 	}
 	ita = &ipi_tlb_args;
-	mtx_lock_spin(&smp_ipi_mtx);
+	mtx_lock_spin(&ipi_mtx);
 	ita->ita_mask = cpus;
 	ita->ita_pmap = pm;
 	cpu_ipi_selected(cpus, 0, (u_long)tl_ipi_tlb_context_demap,
@@ -241,7 +259,7 @@ ipi_tlb_page_demap(struct pmap *pm, vm_offset_t va)
 	struct ipi_tlb_args *ita;
 	cpuset_t cpus;
 
-	if (smp_cpus == 1)
+	if (__predict_false(smp_started == 0))
 		return (NULL);
 	sched_pin();
 	cpus = pm->pm_active;
@@ -252,7 +270,7 @@ ipi_tlb_page_demap(struct pmap *pm, vm_offset_t va)
 		return (NULL);
 	}
 	ita = &ipi_tlb_args;
-	mtx_lock_spin(&smp_ipi_mtx);
+	mtx_lock_spin(&ipi_mtx);
 	ita->ita_mask = cpus;
 	ita->ita_pmap = pm;
 	ita->ita_va = va;
@@ -266,7 +284,7 @@ ipi_tlb_range_demap(struct pmap *pm, vm_offset_t start, vm_offset_t end)
 	struct ipi_tlb_args *ita;
 	cpuset_t cpus;
 
-	if (smp_cpus == 1)
+	if (__predict_false(smp_started == 0))
 		return (NULL);
 	sched_pin();
 	cpus = pm->pm_active;
@@ -277,7 +295,7 @@ ipi_tlb_range_demap(struct pmap *pm, vm_offset_t start, vm_offset_t end)
 		return (NULL);
 	}
 	ita = &ipi_tlb_args;
-	mtx_lock_spin(&smp_ipi_mtx);
+	mtx_lock_spin(&ipi_mtx);
 	ita->ita_mask = cpus;
 	ita->ita_pmap = pm;
 	ita->ita_start = start;
@@ -292,10 +310,10 @@ ipi_wait(void *cookie)
 {
 	volatile cpuset_t *mask;
 
-	if ((mask = cookie) != NULL) {
+	if (__predict_false((mask = cookie) != NULL)) {
 		while (!CPU_EMPTY(mask))
 			;
-		mtx_unlock_spin(&smp_ipi_mtx);
+		mtx_unlock_spin(&ipi_mtx);
 		sched_unpin();
 	}
 }
diff --git a/sys/sparc64/sparc64/machdep.c b/sys/sparc64/sparc64/machdep.c
index af8c619..f016eaa 100644
--- a/sys/sparc64/sparc64/machdep.c
+++ b/sys/sparc64/sparc64/machdep.c
@@ -503,7 +503,7 @@ sparc64_init(caddr_t mdp, u_long o1, u_long o2, u_long o3, ofw_vec_t *vec)
 	}
 
 #ifdef SMP
-	mp_init(cpu_impl);
+	mp_init();
 #endif
 
 	/*
diff --git a/sys/sparc64/sparc64/mp_machdep.c b/sys/sparc64/sparc64/mp_machdep.c
index 0f977b3..c2c4e3e 100644
--- a/sys/sparc64/sparc64/mp_machdep.c
+++ b/sys/sparc64/sparc64/mp_machdep.c
@@ -82,6 +82,7 @@ __FBSDID("$FreeBSD$");
 #include <machine/atomic.h>
 #include <machine/bus.h>
 #include <machine/cpu.h>
+#include <machine/cpufunc.h>
 #include <machine/md_var.h>
 #include <machine/metadata.h>
 #include <machine/ofw_machdep.h>
@@ -113,12 +114,13 @@ struct	ipi_rd_args ipi_rd_args;
 struct	ipi_tlb_args ipi_tlb_args;
 struct	pcb stoppcbs[MAXCPU];
 
+struct	mtx ipi_mtx;
+
 cpu_ipi_selected_t *cpu_ipi_selected;
 cpu_ipi_single_t *cpu_ipi_single;
 
 static vm_offset_t mp_tramp;
 static u_int cpuid_to_mid[MAXCPU];
-static int isjbus;
 static volatile cpuset_t shutdown_cpus;
 
 static void ap_count(phandle_t node, u_int mid, u_int cpu_impl);
@@ -138,7 +140,7 @@ static cpu_ipi_single_t spitfire_ipi_single;
 SYSINIT(cpu_mp_unleash, SI_SUB_SMP, SI_ORDER_FIRST, cpu_mp_unleash, NULL);
 
 void
-mp_init(u_int cpu_impl)
+mp_init(void)
 {
 	struct tte *tp;
 	int i;
@@ -157,24 +159,6 @@ mp_init(u_int cpu_impl)
 	}
 	for (i = 0; i < PAGE_SIZE; i += sizeof(vm_offset_t))
 		flush(mp_tramp + i);
-
-	/*
-	 * On UP systems cpu_ipi_selected() can be called while
-	 * cpu_mp_start() wasn't so initialize these here.
-	 */
-	if (cpu_impl == CPU_IMPL_ULTRASPARCIIIi ||
-	    cpu_impl == CPU_IMPL_ULTRASPARCIIIip) {
-		isjbus = 1;
-		cpu_ipi_selected = jalapeno_ipi_selected;
-		cpu_ipi_single = jalapeno_ipi_single;
-	} else if (cpu_impl == CPU_IMPL_SPARC64V ||
-	    cpu_impl >= CPU_IMPL_ULTRASPARCIII) {
-		cpu_ipi_selected = cheetah_ipi_selected;
-		cpu_ipi_single = cheetah_ipi_single;
-	} else {
-		cpu_ipi_selected = spitfire_ipi_selected;
-		cpu_ipi_single = spitfire_ipi_single;
-	}
 }
 
 static void
@@ -219,7 +203,7 @@ foreach_ap(phandle_t node, void (*func)(phandle_t node, u_int mid,
  * Probe for other CPUs.
  */
 void
-cpu_mp_setmaxid()
+cpu_mp_setmaxid(void)
 {
 
 	CPU_SETOF(curcpu, &all_cpus);
@@ -277,6 +261,25 @@ sun4u_startcpu(phandle_t cpu, void *func, u_long arg)
 void
 cpu_mp_start(void)
 {
+	u_int cpu_impl, isjbus;
+
+	mtx_init(&ipi_mtx, "ipi", NULL, MTX_SPIN);
+
+	isjbus = 0;
+	cpu_impl = PCPU_GET(impl);
+	if (cpu_impl == CPU_IMPL_ULTRASPARCIIIi ||
+	    cpu_impl == CPU_IMPL_ULTRASPARCIIIip) {
+		isjbus = 1;
+		cpu_ipi_selected = jalapeno_ipi_selected;
+		cpu_ipi_single = jalapeno_ipi_single;
+	} else if (cpu_impl == CPU_IMPL_SPARC64V ||
+	    cpu_impl >= CPU_IMPL_ULTRASPARCIII) {
+		cpu_ipi_selected = cheetah_ipi_selected;
+		cpu_ipi_single = cheetah_ipi_single;
+	} else {
+		cpu_ipi_selected = spitfire_ipi_selected;
+		cpu_ipi_single = spitfire_ipi_single;
+	}
 
 	intr_setup(PIL_AST, cpu_ipi_ast, -1, NULL, NULL);
 	intr_setup(PIL_RENDEZVOUS, (ih_func_t *)smp_rendezvous_action,
@@ -360,7 +363,7 @@ cpu_mp_announce(void)
 }
 
 static void
-cpu_mp_unleash(void *v)
+cpu_mp_unleash(void *v __unused)
 {
 	volatile struct cpu_start_args *csa;
 	struct pcpu *pc;
@@ -407,7 +410,6 @@ cpu_mp_unleash(void *v)
 
 	membar(StoreLoad);
 	csa->csa_count = 0;
-	smp_started = 1;
 }
 
 void
@@ -464,6 +466,9 @@ cpu_mp_bootstrap(struct pcpu *pc)
 	while (csa->csa_count != 0)
 		;
 
+	if (smp_cpus == mp_ncpus)
+		atomic_store_rel_int(&smp_started, 1);
+
 	/* Start per-CPU event timers. */
 	cpu_initclocks_ap();
 
@@ -530,7 +535,7 @@ cpu_ipi_stop(struct trapframe *tf __unused)
 }
 
 static void
-cpu_ipi_preempt(struct trapframe *tf)
+cpu_ipi_preempt(struct trapframe *tf __unused)
 {
 
 	sched_preempt(curthread);
@@ -573,9 +578,11 @@ spitfire_ipi_single(u_int cpu, u_long d0, u_long d1, u_long d2)
 	u_int mid;
 	int i;
 
+	mtx_assert(&ipi_mtx, MA_OWNED);
 	KASSERT(cpu != curcpu, ("%s: CPU can't IPI itself", __func__));
 	KASSERT((ldxa(0, ASI_INTR_DISPATCH_STATUS) & IDR_BUSY) == 0,
 	    ("%s: outstanding dispatch", __func__));
+
 	mid = cpuid_to_mid[cpu];
 	for (i = 0; i < IPI_RETRIES; i++) {
 		s = intr_disable();
@@ -601,12 +608,6 @@ spitfire_ipi_single(u_int cpu, u_long d0, u_long d1, u_long d2)
 		intr_restore(s);
 		if ((ids & (IDR_BUSY | IDR_NACK)) == 0)
 			return;
-		/*
-		 * Leave interrupts enabled for a bit before retrying
-		 * in order to avoid deadlocks if the other CPU is also
-		 * trying to send an IPI.
-		 */
-		DELAY(2);
 	}
 	if (kdb_active != 0 || panicstr != NULL)
 		printf("%s: couldn't send IPI to module 0x%u\n",
@@ -624,10 +625,12 @@ cheetah_ipi_single(u_int cpu, u_long d0, u_long d1, u_long d2)
 	u_int mid;
 	int i;
 
+	mtx_assert(&ipi_mtx, MA_OWNED);
 	KASSERT(cpu != curcpu, ("%s: CPU can't IPI itself", __func__));
 	KASSERT((ldxa(0, ASI_INTR_DISPATCH_STATUS) &
 	    IDR_CHEETAH_ALL_BUSY) == 0,
 	    ("%s: outstanding dispatch", __func__));
+
 	mid = cpuid_to_mid[cpu];
 	for (i = 0; i < IPI_RETRIES; i++) {
 		s = intr_disable();
@@ -644,12 +647,6 @@ cheetah_ipi_single(u_int cpu, u_long d0, u_long d1, u_long d2)
 		intr_restore(s);
 		if ((ids & (IDR_BUSY | IDR_NACK)) == 0)
 			return;
-		/*
-		 * Leave interrupts enabled for a bit before retrying
-		 * in order to avoid deadlocks if the other CPU is also
-		 * trying to send an IPI.
-		 */
-		DELAY(2);
 	}
 	if (kdb_active != 0 || panicstr != NULL)
 		printf("%s: couldn't send IPI to module 0x%u\n",
@@ -669,13 +666,14 @@ cheetah_ipi_selected(cpuset_t cpus, u_long d0, u_long d1, u_long d2)
 	u_int cpu;
 	int i;
 
+	mtx_assert(&ipi_mtx, MA_OWNED);
+	KASSERT(!CPU_EMPTY(&cpus), ("%s: no CPUs to IPI", __func__));
 	KASSERT(!CPU_ISSET(curcpu, &cpus), ("%s: CPU can't IPI itself",
 	    __func__));
 	KASSERT((ldxa(0, ASI_INTR_DISPATCH_STATUS) &
 	    IDR_CHEETAH_ALL_BUSY) == 0,
 	    ("%s: outstanding dispatch", __func__));
-	if (CPU_EMPTY(&cpus))
-		return;
+
 	ids = 0;
 	for (i = 0; i < IPI_RETRIES * mp_ncpus; i++) {
 		s = intr_disable();
@@ -709,12 +707,6 @@ cheetah_ipi_selected(cpuset_t cpus, u_long d0, u_long d1, u_long d2)
 		}
 		if (CPU_EMPTY(&cpus))
 			return;
-		/*
-		 * Leave interrupts enabled for a bit before retrying
-		 * in order to avoid deadlocks if the other CPUs are
-		 * also trying to send IPIs.
-		 */
-		DELAY(2 * mp_ncpus);
 	}
 	if (kdb_active != 0 || panicstr != NULL)
 		printf("%s: couldn't send IPI (cpus=%s ids=0x%lu)\n",
@@ -732,10 +724,12 @@ jalapeno_ipi_single(u_int cpu, u_long d0, u_long d1, u_long d2)
 	u_int busy, busynack, mid;
 	int i;
 
+	mtx_assert(&ipi_mtx, MA_OWNED);
 	KASSERT(cpu != curcpu, ("%s: CPU can't IPI itself", __func__));
 	KASSERT((ldxa(0, ASI_INTR_DISPATCH_STATUS) &
 	    IDR_CHEETAH_ALL_BUSY) == 0,
 	    ("%s: outstanding dispatch", __func__));
+
 	mid = cpuid_to_mid[cpu];
 	busy = IDR_BUSY << (2 * mid);
 	busynack = (IDR_BUSY | IDR_NACK) << (2 * mid);
@@ -754,12 +748,6 @@ jalapeno_ipi_single(u_int cpu, u_long d0, u_long d1, u_long d2)
 		intr_restore(s);
 		if ((ids & busynack) == 0)
 			return;
-		/*
-		 * Leave interrupts enabled for a bit before retrying
-		 * in order to avoid deadlocks if the other CPU is also
-		 * trying to send an IPI.
-		 */
-		DELAY(2);
 	}
 	if (kdb_active != 0 || panicstr != NULL)
 		printf("%s: couldn't send IPI to module 0x%u\n",
@@ -778,13 +766,14 @@ jalapeno_ipi_selected(cpuset_t cpus, u_long d0, u_long d1, u_long d2)
 	u_int cpu;
 	int i;
 
+	mtx_assert(&ipi_mtx, MA_OWNED);
+	KASSERT(!CPU_EMPTY(&cpus), ("%s: no CPUs to IPI", __func__));
 	KASSERT(!CPU_ISSET(curcpu, &cpus), ("%s: CPU can't IPI itself",
 	    __func__));
 	KASSERT((ldxa(0, ASI_INTR_DISPATCH_STATUS) &
 	    IDR_CHEETAH_ALL_BUSY) == 0,
 	    ("%s: outstanding dispatch", __func__));
-	if (CPU_EMPTY(&cpus))
-		return;
+
 	ids = 0;
 	for (i = 0; i < IPI_RETRIES * mp_ncpus; i++) {
 		s = intr_disable();
@@ -811,12 +800,6 @@ jalapeno_ipi_selected(cpuset_t cpus, u_long d0, u_long d1, u_long d2)
 				if ((ids & (IDR_NACK <<
 				    (2 * cpuid_to_mid[cpu]))) == 0)
 					CPU_CLR(cpu, &cpus);
-		/*
-		 * Leave interrupts enabled for a bit before retrying
-		 * in order to avoid deadlocks if the other CPUs are
-		 * also trying to send IPIs.
-		 */
-		DELAY(2 * mp_ncpus);
 	}
 	if (kdb_active != 0 || panicstr != NULL)
 		printf("%s: couldn't send IPI (cpus=%s ids=0x%lu)\n",
diff --git a/sys/sparc64/sparc64/tick.c b/sys/sparc64/sparc64/tick.c
index 130efa6..2072b18 100644
--- a/sys/sparc64/sparc64/tick.c
+++ b/sys/sparc64/sparc64/tick.c
@@ -31,8 +31,6 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
-#include <sys/lock.h>
-#include <sys/mutex.h>
 #include <sys/pcpu.h>
 #include <sys/proc.h>
 #include <sys/sched.h>
@@ -46,7 +44,6 @@ __FBSDID("$FreeBSD$");
 #include <vm/vm.h>
 #include <vm/pmap.h>
 
-#include <machine/cpu.h>
 #include <machine/frame.h>
 #include <machine/intr_machdep.h>
 #include <machine/smp.h>
@@ -326,7 +323,7 @@ tick_get_timecount_up(struct timecounter *tc)
 static u_int
 stick_get_timecount_mp(struct timecounter *tc)
 {
-	u_long stick;
+	static u_long stick;
 
 	sched_pin();
 	if (curcpu == 0)
@@ -340,7 +337,7 @@ stick_get_timecount_mp(struct timecounter *tc)
 static u_int
 tick_get_timecount_mp(struct timecounter *tc)
 {
-	u_long tick;
+	static u_long tick;
 
 	sched_pin();
 	if (curcpu == 0)