hardirq.h

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#ifndef LINUX_HARDIRQ_H
#define LINUX_HARDIRQ_H

#include <linux/preempt.h>
#include <linux/lockdep.h>
#include <linux/ftrace_irq.h>
#include <asm/hardirq.h>

/*
 * We put the hardirq and softirq counter into the preemption
 * counter. The bitmask has the following meaning:
 *
 * - bits 0-7 are the preemption count (max preemption depth: 256)
 * - bits 8-15 are the softirq count (max # of softirqs: 256)
 *
 * The hardirq count can in theory reach the same as NR_IRQS.
 * In reality, the number of nested IRQS is limited to the stack
 * size as well. For archs with over 1000 IRQS it is not practical
 * to expect that they will all nest. We give a max of 10 bits for
 * hardirq nesting. An arch may choose to give less than 10 bits.
 * m68k expects it to be 8.
 *
 * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
 * - bit 26 is the NMI_MASK
 * - bit 27 is the PREEMPT_ACTIVE flag
 *
 * PREEMPT_MASK: 0x000000ff
 * SOFTIRQ_MASK: 0x0000ff00
 * HARDIRQ_MASK: 0x03ff0000
 *     NMI_MASK: 0x04000000
 */
#define PREEMPT_BITS    8
#define SOFTIRQ_BITS    8
#define NMI_BITS    1

#define MAX_HARDIRQ_BITS 10

#ifndef HARDIRQ_BITS
# define HARDIRQ_BITS   MAX_HARDIRQ_BITS
#endif

#if HARDIRQ_BITS > MAX_HARDIRQ_BITS
#error HARDIRQ_BITS too high!
#endif

#define PREEMPT_SHIFT   0
#define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
#define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
#define NMI_SHIFT   (HARDIRQ_SHIFT + HARDIRQ_BITS)

#define __IRQ_MASK(x)   ((1UL << (x))-1)

#define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
#define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
#define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
#define NMI_MASK    (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)

#define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
#define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
#define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
#define NMI_OFFSET  (1UL << NMI_SHIFT)

#define SOFTIRQ_DISABLE_OFFSET  (2 * SOFTIRQ_OFFSET)

#ifndef PREEMPT_ACTIVE
#define PREEMPT_ACTIVE_BITS 1
#define PREEMPT_ACTIVE_SHIFT    (NMI_SHIFT + NMI_BITS)
#define PREEMPT_ACTIVE  (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
#endif

#if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
#error PREEMPT_ACTIVE is too low!
#endif

#define hardirq_count() (preempt_count() & HARDIRQ_MASK)
#define softirq_count() (preempt_count() & SOFTIRQ_MASK)
#define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
                 | NMI_MASK))

/*
 * Are we doing bottom half or hardware interrupt processing?
 * Are we in a softirq context? Interrupt context?
 * in_softirq - Are we currently processing softirq or have bh disabled?
 * in_serving_softirq - Are we currently processing softirq?
 */
#define in_irq()        (hardirq_count())
#define in_softirq()        (softirq_count())
#define in_interrupt()      (irq_count())
#define in_serving_softirq()    (softirq_count() & SOFTIRQ_OFFSET)

/*
 * Are we in NMI context?
 */
#define in_nmi()    (preempt_count() & NMI_MASK)

#if defined(CONFIG_PREEMPT_COUNT)
# define PREEMPT_CHECK_OFFSET 1
#else
# define PREEMPT_CHECK_OFFSET 0
#endif

/*
 * Are we running in atomic context?  WARNING: this macro cannot
 * always detect atomic context; in particular, it cannot know about
 * held spinlocks in non-preemptible kernels.  Thus it should not be
 * used in the general case to determine whether sleeping is possible.
 * Do not use in_atomic() in driver code.
 */
#define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0)

/*
 * Check whether we were atomic before we did preempt_disable():
 * (used by the scheduler, *after* releasing the kernel lock)
 */
#define in_atomic_preempt_off() \
        ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)

#ifdef CONFIG_PREEMPT_COUNT
# define preemptible()  (preempt_count() == 0 && !irqs_disabled())
# define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
#else
# define preemptible()  0
# define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
#endif

#if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
extern void synchronize_irq(unsigned int irq);
#else
# define synchronize_irq(irq)   barrier()
#endif

struct task_struct;

#if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
static inline void vtime_account(struct task_struct *tsk)
{
}
#else
extern void vtime_account(struct task_struct *tsk);
#endif

#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)

static inline void rcu_nmi_enter(void)
{
}

static inline void rcu_nmi_exit(void)
{
}

#else
extern void rcu_nmi_enter(void);
extern void rcu_nmi_exit(void);
#endif

/*
 * It is safe to do non-atomic ops on ->hardirq_context,
 * because NMI handlers may not preempt and the ops are
 * always balanced, so the interrupted value of ->hardirq_context
 * will always be restored.
 */
#define __irq_enter()                   \
    do {                        \
        vtime_account(current);     \
        add_preempt_count(HARDIRQ_OFFSET);  \
        trace_hardirq_enter();          \
    } while (0)

/*
 * Enter irq context (on NO_HZ, update jiffies):
 */
extern void irq_enter(void);

/*
 * Exit irq context without processing softirqs:
 */
#define __irq_exit()                    \
    do {                        \
        trace_hardirq_exit();           \
        vtime_account(current);     \
        sub_preempt_count(HARDIRQ_OFFSET);  \
    } while (0)

/*
 * Exit irq context and process softirqs if needed:
 */
extern void irq_exit(void);

#define nmi_enter()                     \
    do {                            \
        ftrace_nmi_enter();             \
        BUG_ON(in_nmi());               \
        add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
        lockdep_off();                  \
        rcu_nmi_enter();                \
        trace_hardirq_enter();              \
    } while (0)

#define nmi_exit()                      \
    do {                            \
        trace_hardirq_exit();               \
        rcu_nmi_exit();                 \
        lockdep_on();                   \
        BUG_ON(!in_nmi());              \
        sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
        ftrace_nmi_exit();              \
    } while (0)

#endif /* LINUX_HARDIRQ_H */