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 #ifndef PREEMPT_ACTIVE
  68 #define PREEMPT_ACTIVE_BITS     1
  69 #define PREEMPT_ACTIVE_SHIFT    (NMI_SHIFT + NMI_BITS)
  70 #define PREEMPT_ACTIVE  (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
  71 #endif
  72
  73 #if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
  74 #error PREEMPT_ACTIVE is too low!
  75 #endif
  76
  77 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  78 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  79 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  80                                  | NMI_MASK))
  81
  82 /*
  83  * Are we doing bottom half or hardware interrupt processing?
  84  * Are we in a softirq context? Interrupt context?
  85  */
  86 #define in_irq()                (hardirq_count())
  87 #define in_softirq()            (softirq_count())
  88 #define in_interrupt()          (irq_count())
  89
  90 /*
  91  * Are we in NMI context?
  92  */
  93 #define in_nmi()        (preempt_count() & NMI_MASK)
  94
  95 #if defined(CONFIG_PREEMPT)
  96 # define PREEMPT_INATOMIC_BASE kernel_locked()
  97 # define PREEMPT_CHECK_OFFSET 1
  98 #else
  99 # define PREEMPT_INATOMIC_BASE 0
 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) != PREEMPT_INATOMIC_BASE)
 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
 120 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 121 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 122 #else
 123 # define preemptible()  0
 124 # define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
 125 #endif
 126
 127 #if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
 128 extern void synchronize_irq(unsigned int irq);
 129 #else
 130 # define synchronize_irq(irq)   barrier()
 131 #endif
 132
 133 struct task_struct;
 134
 135 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
 136 static inline void account_system_vtime(struct task_struct *tsk)
 137 {
 138 }
 139 #endif
 140
 141 #if defined(CONFIG_NO_HZ)
 142 #if defined(CONFIG_TINY_RCU)
 143 extern void rcu_enter_nohz(void);
 144 extern void rcu_exit_nohz(void);
 145
 146 static inline void rcu_irq_enter(void)
 147 {
 148         rcu_exit_nohz();
 149 }
 150
 151 static inline void rcu_irq_exit(void)
 152 {
 153         rcu_enter_nohz();
 154 }
 155
 156 static inline void rcu_nmi_enter(void)
 157 {
 158 }
 159
 160 static inline void rcu_nmi_exit(void)
 161 {
 162 }
 163
 164 #else
 165 extern void rcu_irq_enter(void);
 166 extern void rcu_irq_exit(void);
 167 extern void rcu_nmi_enter(void);
 168 extern void rcu_nmi_exit(void);
 169 #endif
 170 #else
 171 # define rcu_irq_enter() do { } while (0)
 172 # define rcu_irq_exit() do { } while (0)
 173 # define rcu_nmi_enter() do { } while (0)
 174 # define rcu_nmi_exit() do { } while (0)
 175 #endif /* #if defined(CONFIG_NO_HZ) */
 176
 177 /*
 178  * It is safe to do non-atomic ops on ->hardirq_context,
 179  * because NMI handlers may not preempt and the ops are
 180  * always balanced, so the interrupted value of ->hardirq_context
 181  * will always be restored.
 182  */
 183 #define __irq_enter()                                   \
 184         do {                                            \
 185                 account_system_vtime(current);          \
 186                 add_preempt_count(HARDIRQ_OFFSET);      \
 187                 trace_hardirq_enter();                  \
 188         } while (0)
 189
 190 /*
 191  * Enter irq context (on NO_HZ, update jiffies):
 192  */
 193 extern void irq_enter(void);
 194
 195 /*
 196  * Exit irq context without processing softirqs:
 197  */
 198 #define __irq_exit()                                    \
 199         do {                                            \
 200                 trace_hardirq_exit();                   \
 201                 account_system_vtime(current);          \
 202                 sub_preempt_count(HARDIRQ_OFFSET);      \
 203         } while (0)
 204
 205 /*
 206  * Exit irq context and process softirqs if needed:
 207  */
 208 extern void irq_exit(void);
 209
 210 #define nmi_enter()                                             \
 211         do {                                                    \
 212                 ftrace_nmi_enter();                             \
 213                 BUG_ON(in_nmi());                               \
 214                 add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 215                 lockdep_off();                                  \
 216                 rcu_nmi_enter();                                \
 217                 trace_hardirq_enter();                          \
 218         } while (0)
 219
 220 #define nmi_exit()                                              \
 221         do {                                                    \
 222                 trace_hardirq_exit();                           \
 223                 rcu_nmi_exit();                                 \
 224                 lockdep_on();                                   \
 225                 BUG_ON(!in_nmi());                              \
 226                 sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 227                 ftrace_nmi_exit();                              \
 228         } while (0)
 229
 230 #endif /* LINUX_HARDIRQ_H */