arch/i386/mach-xen/irqflags.c

   1 #include <linux/module.h>
   2 #include <linux/smp.h>
   3 #include <asm/irqflags.h>
   4 #include <asm/hypervisor.h>
   5
   6 /* interrupt control.. */
   7
   8 /*
   9  * The use of 'barrier' in the following reflects their use as local-lock
  10  * operations. Reentrancy must be prevented (e.g., __cli()) /before/ following
  11  * critical operations are executed. All critical operations must complete
  12  * /before/ reentrancy is permitted (e.g., __sti()). Alpha architecture also
  13  * includes these barriers, for example.
  14  */
  15
  16 unsigned long __raw_local_save_flags(void)
  17 {
  18         struct vcpu_info *_vcpu;
  19         unsigned long flags;
  20
  21         preempt_disable();
  22         _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id];
  23         flags = _vcpu->evtchn_upcall_mask;
  24         preempt_enable();
  25
  26         return flags;
  27 }
  28 EXPORT_SYMBOL(__raw_local_save_flags);
  29
  30 void raw_local_irq_restore(unsigned long flags)
  31 {
  32         struct vcpu_info *_vcpu;
  33
  34         preempt_disable();
  35         _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id];
  36         if ((_vcpu->evtchn_upcall_mask = flags) == 0) {
  37                 barrier(); /* unmask then check (avoid races) */
  38                 if (unlikely(_vcpu->evtchn_upcall_pending))
  39                         force_evtchn_callback();
  40                 preempt_enable();
  41         } else
  42                 preempt_enable_no_resched();
  43 }
  44 EXPORT_SYMBOL(raw_local_irq_restore);
  45
  46 void raw_local_irq_disable(void)
  47 {
  48         struct vcpu_info *_vcpu;
  49
  50         preempt_disable();
  51         _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id];
  52         _vcpu->evtchn_upcall_mask = 1;
  53         preempt_enable_no_resched();
  54 }
  55 EXPORT_SYMBOL(raw_local_irq_disable);
  56
  57 void raw_local_irq_enable(void)
  58 {
  59         struct vcpu_info *_vcpu;
  60
  61         preempt_disable();
  62         _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id];
  63         _vcpu->evtchn_upcall_mask = 0;
  64         barrier(); /* unmask then check (avoid races) */
  65         if (unlikely(_vcpu->evtchn_upcall_pending))
  66                 force_evtchn_callback();
  67         preempt_enable();
  68 }
  69 EXPORT_SYMBOL(raw_local_irq_enable);
  70
  71 /*
  72  * For spinlocks, etc.:
  73  */
  74
  75 unsigned long __raw_local_irq_save(void)
  76 {
  77         struct vcpu_info *_vcpu;
  78         unsigned long flags;
  79
  80         preempt_disable();
  81         _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id];
  82         flags = _vcpu->evtchn_upcall_mask;
  83         _vcpu->evtchn_upcall_mask = 1;
  84         preempt_enable_no_resched();
  85
  86         return flags;
  87 }
  88 EXPORT_SYMBOL(__raw_local_irq_save);
  89
  90 /* Cannot use preempt_enable() here as we would recurse in preempt_sched(). */
  91 int raw_irqs_disabled(void)
  92 {
  93         struct vcpu_info *_vcpu;
  94         int disabled;
  95
  96         preempt_disable();
  97         _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id];
  98         disabled = (_vcpu->evtchn_upcall_mask != 0);
  99         preempt_enable_no_resched();
 100
 101         return disabled;
 102 }
 103 EXPORT_SYMBOL(raw_irqs_disabled);