include/linux/hardirq.h

   1 #ifndef LINUX_HARDIRQ_H
   2 #define LINUX_HARDIRQ_H
   3
   4 #include <linux/preempt.h>
   5 #include <linux/smp_lock.h>
   6 #include <linux/lockdep.h>
   7 #include <linux/ftrace_irq.h>
   8 #include <asm/hardirq.h>
   9 #include <asm/system.h>
  10
  11 /*
  12  * We put the hardirq and softirq counter into the preemption
  13  * counter. The bitmask has the following meaning:
  14  *
  15  * - bits 0-7 are the preemption count (max preemption depth: 256)
  16  * - bits 8-15 are the softirq count (max # of softirqs: 256)
  17  *
  18  * The hardirq count can be overridden per architecture, the default is:
  19  *
  20  * - bits 16-27 are the hardirq count (max # of hardirqs: 4096)
  21  * - ( bit 28 is the PREEMPT_ACTIVE flag. )
  22  *
  23  * PREEMPT_MASK: 0x000000ff
  24  * SOFTIRQ_MASK: 0x0000ff00
  25  * HARDIRQ_MASK: 0x0fff0000
  26  */
  27 #define PREEMPT_BITS    8
  28 #define SOFTIRQ_BITS    8
  29
  30 #ifndef HARDIRQ_BITS
  31 #define HARDIRQ_BITS    12
  32
  33 #ifndef MAX_HARDIRQS_PER_CPU
  34 #define MAX_HARDIRQS_PER_CPU NR_IRQS
  35 #endif
  36
  37 /*
  38  * The hardirq mask has to be large enough to have space for potentially
  39  * all IRQ sources in the system nesting on a single CPU.
  40  */
  41 #if (1 << HARDIRQ_BITS) < MAX_HARDIRQS_PER_CPU
  42 # error HARDIRQ_BITS is too low!
  43 #endif
  44 #endif
  45
  46 #define PREEMPT_SHIFT   0
  47 #define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
  48 #define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  49
  50 #define __IRQ_MASK(x)   ((1UL << (x))-1)
  51
  52 #define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
  53 #define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
  54 #define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
  55
  56 #define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
  57 #define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
  58 #define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
  59
  60 #if PREEMPT_ACTIVE < (1 << (HARDIRQ_SHIFT + HARDIRQ_BITS))
  61 #error PREEMPT_ACTIVE is too low!
  62 #endif
  63
  64 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  65 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  66 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK))
  67
  68 /*
  69  * Are we doing bottom half or hardware interrupt processing?
  70  * Are we in a softirq context? Interrupt context?
  71  */
  72 #define in_irq()                (hardirq_count())
  73 #define in_softirq()            (softirq_count())
  74 #define in_interrupt()          (irq_count())
  75
  76 #if defined(CONFIG_PREEMPT)
  77 # define PREEMPT_INATOMIC_BASE kernel_locked()
  78 # define PREEMPT_CHECK_OFFSET 1
  79 #else
  80 # define PREEMPT_INATOMIC_BASE 0
  81 # define PREEMPT_CHECK_OFFSET 0
  82 #endif
  83
  84 /*
  85  * Are we running in atomic context?  WARNING: this macro cannot
  86  * always detect atomic context; in particular, it cannot know about
  87  * held spinlocks in non-preemptible kernels.  Thus it should not be
  88  * used in the general case to determine whether sleeping is possible.
  89  * Do not use in_atomic() in driver code.
  90  */
  91 #define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_INATOMIC_BASE)
  92
  93 /*
  94  * Check whether we were atomic before we did preempt_disable():
  95  * (used by the scheduler, *after* releasing the kernel lock)
  96  */
  97 #define in_atomic_preempt_off() \
  98                 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
  99
 100 #ifdef CONFIG_PREEMPT
 101 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 102 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 103 #else
 104 # define preemptible()  0
 105 # define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
 106 #endif
 107
 108 #ifdef CONFIG_SMP
 109 extern void synchronize_irq(unsigned int irq);
 110 #else
 111 # define synchronize_irq(irq)   barrier()
 112 #endif
 113
 114 struct task_struct;
 115
 116 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
 117 static inline void account_system_vtime(struct task_struct *tsk)
 118 {
 119 }
 120 #endif
 121
 122 #if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU)
 123 extern void rcu_irq_enter(void);
 124 extern void rcu_irq_exit(void);
 125 extern void rcu_nmi_enter(void);
 126 extern void rcu_nmi_exit(void);
 127 #else
 128 # define rcu_irq_enter() do { } while (0)
 129 # define rcu_irq_exit() do { } while (0)
 130 # define rcu_nmi_enter() do { } while (0)
 131 # define rcu_nmi_exit() do { } while (0)
 132 #endif /* #if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU) */
 133
 134 /*
 135  * It is safe to do non-atomic ops on ->hardirq_context,
 136  * because NMI handlers may not preempt and the ops are
 137  * always balanced, so the interrupted value of ->hardirq_context
 138  * will always be restored.
 139  */
 140 #define __irq_enter()                                   \
 141         do {                                            \
 142                 account_system_vtime(current);          \
 143                 add_preempt_count(HARDIRQ_OFFSET);      \
 144                 trace_hardirq_enter();                  \
 145         } while (0)
 146
 147 /*
 148  * Enter irq context (on NO_HZ, update jiffies):
 149  */
 150 extern void irq_enter(void);
 151
 152 /*
 153  * Exit irq context without processing softirqs:
 154  */
 155 #define __irq_exit()                                    \
 156         do {                                            \
 157                 trace_hardirq_exit();                   \
 158                 account_system_vtime(current);          \
 159                 sub_preempt_count(HARDIRQ_OFFSET);      \
 160         } while (0)
 161
 162 /*
 163  * Exit irq context and process softirqs if needed:
 164  */
 165 extern void irq_exit(void);
 166
 167 #define nmi_enter()                             \
 168         do {                                    \
 169                 ftrace_nmi_enter();             \
 170                 lockdep_off();                  \
 171                 rcu_nmi_enter();                \
 172                 __irq_enter();                  \
 173         } while (0)
 174
 175 #define nmi_exit()                              \
 176         do {                                    \
 177                 __irq_exit();                   \
 178                 rcu_nmi_exit();                 \
 179                 lockdep_on();                   \
 180                 ftrace_nmi_exit();              \
 181         } while (0)
 182
 183 #endif /* LINUX_HARDIRQ_H */