include/linux/hardirq.h

   1 #ifndef LINUX_HARDIRQ_H
   2 #define LINUX_HARDIRQ_H
   3
   4 #include <linux/preempt.h>
   5 #ifdef CONFIG_PREEMPT
   6 #include <linux/smp_lock.h>
   7 #endif
   8 #include <linux/lockdep.h>
   9 #include <linux/ftrace_irq.h>
  10 #include <asm/hardirq.h>
  11 #include <asm/system.h>
  12
  13 /*
  14  * We put the hardirq and softirq counter into the preemption
  15  * counter. The bitmask has the following meaning:
  16  *
  17  * - bits 0-7 are the preemption count (max preemption depth: 256)
  18  * - bits 8-15 are the softirq count (max # of softirqs: 256)
  19  *
  20  * The hardirq count can in theory reach the same as NR_IRQS.
  21  * In reality, the number of nested IRQS is limited to the stack
  22  * size as well. For archs with over 1000 IRQS it is not practical
  23  * to expect that they will all nest. We give a max of 10 bits for
  24  * hardirq nesting. An arch may choose to give less than 10 bits.
  25  * m68k expects it to be 8.
  26  *
  27  * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
  28  * - bit 26 is the NMI_MASK
  29  * - bit 28 is the PREEMPT_ACTIVE flag
  30  *
  31  * PREEMPT_MASK: 0x000000ff
  32  * SOFTIRQ_MASK: 0x0000ff00
  33  * HARDIRQ_MASK: 0x03ff0000
  34  *     NMI_MASK: 0x04000000
  35  */
  36 #define PREEMPT_BITS    8
  37 #define SOFTIRQ_BITS    8
  38 #define NMI_BITS        1
  39
  40 #define MAX_HARDIRQ_BITS 10
  41
  42 #ifndef HARDIRQ_BITS
  43 # define HARDIRQ_BITS   MAX_HARDIRQ_BITS
  44 #endif
  45
  46 #if HARDIRQ_BITS > MAX_HARDIRQ_BITS
  47 #error HARDIRQ_BITS too high!
  48 #endif
  49
  50 #define PREEMPT_SHIFT   0
  51 #define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
  52 #define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  53 #define NMI_SHIFT       (HARDIRQ_SHIFT + HARDIRQ_BITS)
  54
  55 #define __IRQ_MASK(x)   ((1UL << (x))-1)
  56
  57 #define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
  58 #define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
  59 #define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
  60 #define NMI_MASK        (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
  61
  62 #define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
  63 #define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
  64 #define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
  65 #define NMI_OFFSET      (1UL << NMI_SHIFT)
  66
  67 #if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
  68 #error PREEMPT_ACTIVE is too low!
  69 #endif
  70
  71 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  72 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  73 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  74                                  | NMI_MASK))
  75
  76 /*
  77  * Are we doing bottom half or hardware interrupt processing?
  78  * Are we in a softirq context? Interrupt context?
  79  */
  80 #define in_irq()                (hardirq_count())
  81 #define in_softirq()            (softirq_count())
  82 #define in_interrupt()          (irq_count())
  83
  84 /*
  85  * Are we in NMI context?
  86  */
  87 #define in_nmi()        (preempt_count() & NMI_MASK)
  88
  89 #if defined(CONFIG_PREEMPT)
  90 # define PREEMPT_INATOMIC_BASE kernel_locked()
  91 # define PREEMPT_CHECK_OFFSET 1
  92 #else
  93 # define PREEMPT_INATOMIC_BASE 0
  94 # define PREEMPT_CHECK_OFFSET 0
  95 #endif
  96
  97 /*
  98  * Are we running in atomic context?  WARNING: this macro cannot
  99  * always detect atomic context; in particular, it cannot know about
 100  * held spinlocks in non-preemptible kernels.  Thus it should not be
 101  * used in the general case to determine whether sleeping is possible.
 102  * Do not use in_atomic() in driver code.
 103  */
 104 #define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_INATOMIC_BASE)
 105
 106 /*
 107  * Check whether we were atomic before we did preempt_disable():
 108  * (used by the scheduler, *after* releasing the kernel lock)
 109  */
 110 #define in_atomic_preempt_off() \
 111                 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
 112
 113 #ifdef CONFIG_PREEMPT
 114 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 115 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 116 #else
 117 # define preemptible()  0
 118 # define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
 119 #endif
 120
 121 #if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
 122 extern void synchronize_irq(unsigned int irq);
 123 #else
 124 # define synchronize_irq(irq)   barrier()
 125 #endif
 126
 127 struct task_struct;
 128
 129 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
 130 static inline void account_system_vtime(struct task_struct *tsk)
 131 {
 132 }
 133 #endif
 134
 135 #if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU)
 136 extern void rcu_irq_enter(void);
 137 extern void rcu_irq_exit(void);
 138 extern void rcu_nmi_enter(void);
 139 extern void rcu_nmi_exit(void);
 140 #else
 141 # define rcu_irq_enter() do { } while (0)
 142 # define rcu_irq_exit() do { } while (0)
 143 # define rcu_nmi_enter() do { } while (0)
 144 # define rcu_nmi_exit() do { } while (0)
 145 #endif /* #if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU) */
 146
 147 /*
 148  * It is safe to do non-atomic ops on ->hardirq_context,
 149  * because NMI handlers may not preempt and the ops are
 150  * always balanced, so the interrupted value of ->hardirq_context
 151  * will always be restored.
 152  */
 153 #define __irq_enter()                                   \
 154         do {                                            \
 155                 account_system_vtime(current);          \
 156                 add_preempt_count(HARDIRQ_OFFSET);      \
 157                 trace_hardirq_enter();                  \
 158         } while (0)
 159
 160 /*
 161  * Enter irq context (on NO_HZ, update jiffies):
 162  */
 163 extern void irq_enter(void);
 164
 165 /*
 166  * Exit irq context without processing softirqs:
 167  */
 168 #define __irq_exit()                                    \
 169         do {                                            \
 170                 trace_hardirq_exit();                   \
 171                 account_system_vtime(current);          \
 172                 sub_preempt_count(HARDIRQ_OFFSET);      \
 173         } while (0)
 174
 175 /*
 176  * Exit irq context and process softirqs if needed:
 177  */
 178 extern void irq_exit(void);
 179
 180 #define nmi_enter()                                             \
 181         do {                                                    \
 182                 ftrace_nmi_enter();                             \
 183                 BUG_ON(in_nmi());                               \
 184                 add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 185                 lockdep_off();                                  \
 186                 rcu_nmi_enter();                                \
 187                 trace_hardirq_enter();                          \
 188         } while (0)
 189
 190 #define nmi_exit()                                              \
 191         do {                                                    \
 192                 trace_hardirq_exit();                           \
 193                 rcu_nmi_exit();                                 \
 194                 lockdep_on();                                   \
 195                 BUG_ON(!in_nmi());                              \
 196                 sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 197                 ftrace_nmi_exit();                              \
 198         } while (0)
 199
 200 #endif /* LINUX_HARDIRQ_H */