linux/include/linux/hardirq.h
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   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)
 126extern 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
 133static inline void rcu_nmi_enter(void)
 134{
 135}
 136
 137static inline void rcu_nmi_exit(void)
 138{
 139}
 140
 141#else
 142extern void rcu_nmi_enter(void);
 143extern 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 */
 162extern 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 */
 177extern 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 */
 200
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