include/linux/hardirq.h

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