diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/Makefile | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/paravirt.c | 24 | ||||
| -rw-r--r-- | arch/x86/xen/smp.c | 171 |
3 files changed, 197 insertions, 1 deletions
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index b78a17b1281..3db651fc8ec 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -7,9 +7,10 @@ extra-y := head_$(BITS).o head$(BITS).o head.o init_task.o vmlinu CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE) ifdef CONFIG_FTRACE -# Do not profile debug utilities +# Do not profile debug and lowlevel utilities CFLAGS_REMOVE_tsc.o = -pg CFLAGS_REMOVE_rtc.o = -pg +CFLAGS_REMOVE_paravirt.o = -pg endif # diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index b4564d089b4..097d8a6797f 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -124,6 +124,7 @@ static void *get_call_destination(u8 type) .pv_irq_ops = pv_irq_ops, .pv_apic_ops = pv_apic_ops, .pv_mmu_ops = pv_mmu_ops, + .pv_lock_ops = pv_lock_ops, }; return *((void **)&tmpl + type); } @@ -267,6 +268,17 @@ enum paravirt_lazy_mode paravirt_get_lazy_mode(void) return __get_cpu_var(paravirt_lazy_mode); } +void __init paravirt_use_bytelocks(void) +{ +#ifdef CONFIG_SMP + pv_lock_ops.spin_is_locked = __byte_spin_is_locked; + pv_lock_ops.spin_is_contended = __byte_spin_is_contended; + pv_lock_ops.spin_lock = __byte_spin_lock; + pv_lock_ops.spin_trylock = __byte_spin_trylock; + pv_lock_ops.spin_unlock = __byte_spin_unlock; +#endif +} + struct pv_info pv_info = { .name = "bare hardware", .paravirt_enabled = 0, @@ -449,6 +461,18 @@ struct pv_mmu_ops pv_mmu_ops = { .set_fixmap = native_set_fixmap, }; +struct pv_lock_ops pv_lock_ops = { +#ifdef CONFIG_SMP + .spin_is_locked = __ticket_spin_is_locked, + .spin_is_contended = __ticket_spin_is_contended, + + .spin_lock = __ticket_spin_lock, + .spin_trylock = __ticket_spin_trylock, + .spin_unlock = __ticket_spin_unlock, +#endif +}; +EXPORT_SYMBOL_GPL(pv_lock_ops); + EXPORT_SYMBOL_GPL(pv_time_ops); EXPORT_SYMBOL (pv_cpu_ops); EXPORT_SYMBOL (pv_mmu_ops); diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index f702199312a..e693812ac59 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -15,6 +15,7 @@ * This does not handle HOTPLUG_CPU yet. */ #include <linux/sched.h> +#include <linux/kernel_stat.h> #include <linux/err.h> #include <linux/smp.h> @@ -35,6 +36,8 @@ #include "xen-ops.h" #include "mmu.h" +static void __cpuinit xen_init_lock_cpu(int cpu); + cpumask_t xen_cpu_initialized_map; static DEFINE_PER_CPU(int, resched_irq); @@ -179,6 +182,8 @@ static void __init xen_smp_prepare_cpus(unsigned int max_cpus) { unsigned cpu; + xen_init_lock_cpu(0); + smp_store_cpu_info(0); cpu_data(0).x86_max_cores = 1; set_cpu_sibling_map(0); @@ -301,6 +306,7 @@ static int __cpuinit xen_cpu_up(unsigned int cpu) clear_tsk_thread_flag(idle, TIF_FORK); #endif xen_setup_timer(cpu); + xen_init_lock_cpu(cpu); per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; @@ -413,6 +419,170 @@ static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } +struct xen_spinlock { + unsigned char lock; /* 0 -> free; 1 -> locked */ + unsigned short spinners; /* count of waiting cpus */ +}; + +static int xen_spin_is_locked(struct raw_spinlock *lock) +{ + struct xen_spinlock *xl = (struct xen_spinlock *)lock; + + return xl->lock != 0; +} + +static int xen_spin_is_contended(struct raw_spinlock *lock) +{ + struct xen_spinlock *xl = (struct xen_spinlock *)lock; + + /* Not strictly true; this is only the count of contended + lock-takers entering the slow path. */ + return xl->spinners != 0; +} + +static int xen_spin_trylock(struct raw_spinlock *lock) +{ + struct xen_spinlock *xl = (struct xen_spinlock *)lock; + u8 old = 1; + + asm("xchgb %b0,%1" + : "+q" (old), "+m" (xl->lock) : : "memory"); + + return old == 0; +} + +static DEFINE_PER_CPU(int, lock_kicker_irq) = -1; +static DEFINE_PER_CPU(struct xen_spinlock *, lock_spinners); + +static inline void spinning_lock(struct xen_spinlock *xl) +{ + __get_cpu_var(lock_spinners) = xl; + wmb(); /* set lock of interest before count */ + asm(LOCK_PREFIX " incw %0" + : "+m" (xl->spinners) : : "memory"); +} + +static inline void unspinning_lock(struct xen_spinlock *xl) +{ + asm(LOCK_PREFIX " decw %0" + : "+m" (xl->spinners) : : "memory"); + wmb(); /* decrement count before clearing lock */ + __get_cpu_var(lock_spinners) = NULL; +} + +static noinline int xen_spin_lock_slow(struct raw_spinlock *lock) +{ + struct xen_spinlock *xl = (struct xen_spinlock *)lock; + int irq = __get_cpu_var(lock_kicker_irq); + int ret; + + /* If kicker interrupts not initialized yet, just spin */ + if (irq == -1) + return 0; + + /* announce we're spinning */ + spinning_lock(xl); + + /* clear pending */ + xen_clear_irq_pending(irq); + + /* check again make sure it didn't become free while + we weren't looking */ + ret = xen_spin_trylock(lock); + if (ret) + goto out; + + /* block until irq becomes pending */ + xen_poll_irq(irq); + kstat_this_cpu.irqs[irq]++; + +out: + unspinning_lock(xl); + return ret; +} + +static void xen_spin_lock(struct raw_spinlock *lock) +{ + struct xen_spinlock *xl = (struct xen_spinlock *)lock; + int timeout; + u8 oldval; + + do { + timeout = 1 << 10; + + asm("1: xchgb %1,%0\n" + " testb %1,%1\n" + " jz 3f\n" + "2: rep;nop\n" + " cmpb $0,%0\n" + " je 1b\n" + " dec %2\n" + " jnz 2b\n" + "3:\n" + : "+m" (xl->lock), "=q" (oldval), "+r" (timeout) + : "1" (1) + : "memory"); + + } while (unlikely(oldval != 0 && !xen_spin_lock_slow(lock))); +} + +static noinline void xen_spin_unlock_slow(struct xen_spinlock *xl) +{ + int cpu; + + for_each_online_cpu(cpu) { + /* XXX should mix up next cpu selection */ + if (per_cpu(lock_spinners, cpu) == xl) { + xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR); + break; + } + } +} + +static void xen_spin_unlock(struct raw_spinlock *lock) +{ + struct xen_spinlock *xl = (struct xen_spinlock *)lock; + + smp_wmb(); /* make sure no writes get moved after unlock */ + xl->lock = 0; /* release lock */ + + /* make sure unlock happens before kick */ + barrier(); + + if (unlikely(xl->spinners)) + xen_spin_unlock_slow(xl); +} + +static __cpuinit void xen_init_lock_cpu(int cpu) +{ + int irq; + const char *name; + + name = kasprintf(GFP_KERNEL, "spinlock%d", cpu); + irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR, + cpu, + xen_reschedule_interrupt, + IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, + name, + NULL); + + if (irq >= 0) { + disable_irq(irq); /* make sure it's never delivered */ + per_cpu(lock_kicker_irq, cpu) = irq; + } + + printk("cpu %d spinlock event irq %d\n", cpu, irq); +} + +static void __init xen_init_spinlocks(void) +{ + pv_lock_ops.spin_is_locked = xen_spin_is_locked; + pv_lock_ops.spin_is_contended = xen_spin_is_contended; + pv_lock_ops.spin_lock = xen_spin_lock; + pv_lock_ops.spin_trylock = xen_spin_trylock; + pv_lock_ops.spin_unlock = xen_spin_unlock; +} + static const struct smp_ops xen_smp_ops __initdata = { .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu, .smp_prepare_cpus = xen_smp_prepare_cpus, @@ -430,4 +600,5 @@ void __init xen_smp_init(void) { smp_ops = xen_smp_ops; xen_fill_possible_map(); + xen_init_spinlocks(); } |