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