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
  12 /*
  13  * We put the hardirq and softirq counter into the preemption
  14  * counter. The bitmask has the following meaning:
  15  *
  16  * - bits 0-7 are the preemption count (max preemption depth: 256)
  17  * - bits 8-15 are the softirq count (max # of softirqs: 256)
  18  *
  19  * The hardirq count can in theory reach the same as NR_IRQS.
  20  * In reality, the number of nested IRQS is limited to the stack
  21  * size as well. For archs with over 1000 IRQS it is not practical
  22  * to expect that they will all nest. We give a max of 10 bits for
  23  * hardirq nesting. An arch may choose to give less than 10 bits.
  24  * m68k expects it to be 8.
  25  *
  26  * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
  27  * - bit 26 is the NMI_MASK
  28  * - bit 28 is the PREEMPT_ACTIVE flag
  29  *
  30  * PREEMPT_MASK: 0x000000ff
  31  * SOFTIRQ_MASK: 0x0000ff00
  32  * HARDIRQ_MASK: 0x03ff0000
  33  *     NMI_MASK: 0x04000000
  34  */
  35 #define PREEMPT_BITS    8
  36 #define SOFTIRQ_BITS    8
  37 #define NMI_BITS        1
  38
  39 #define MAX_HARDIRQ_BITS 10
  40
  41 #ifndef HARDIRQ_BITS
  42 # define HARDIRQ_BITS   MAX_HARDIRQ_BITS
  43 #endif
  44
  45 #if HARDIRQ_BITS > MAX_HARDIRQ_BITS
  46 #error HARDIRQ_BITS too high!
  47 #endif
  48
  49 #define PREEMPT_SHIFT   0
  50 #define SOFTIRQ_SHIFT   (PREEMPT_SHIFT + PREEMPT_BITS)
  51 #define HARDIRQ_SHIFT   (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  52 #define NMI_SHIFT       (HARDIRQ_SHIFT + HARDIRQ_BITS)
  53
  54 #define __IRQ_MASK(x)   ((1UL << (x))-1)
  55
  56 #define PREEMPT_MASK    (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
  57 #define SOFTIRQ_MASK    (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
  58 #define HARDIRQ_MASK    (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
  59 #define NMI_MASK        (__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
  60
  61 #define PREEMPT_OFFSET  (1UL << PREEMPT_SHIFT)
  62 #define SOFTIRQ_OFFSET  (1UL << SOFTIRQ_SHIFT)
  63 #define HARDIRQ_OFFSET  (1UL << HARDIRQ_SHIFT)
  64 #define NMI_OFFSET      (1UL << NMI_SHIFT)
  65
  66 #define SOFTIRQ_DISABLE_OFFSET  (2 * SOFTIRQ_OFFSET)
  67
  68 #ifndef PREEMPT_ACTIVE
  69 #define PREEMPT_ACTIVE_BITS     1
  70 #define PREEMPT_ACTIVE_SHIFT    (NMI_SHIFT + NMI_BITS)
  71 #define PREEMPT_ACTIVE  (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
  72 #endif
  73
  74 #if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
  75 #error PREEMPT_ACTIVE is too low!
  76 #endif
  77
  78 #define hardirq_count() (preempt_count() & HARDIRQ_MASK)
  79 #define softirq_count() (preempt_count() & SOFTIRQ_MASK)
  80 #define irq_count()     (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  81                                  | NMI_MASK))
  82
  83 /*
  84  * Are we doing bottom half or hardware interrupt processing?
  85  * Are we in a softirq context? Interrupt context?
  86  * in_softirq - Are we currently processing softirq or have bh disabled?
  87  * in_serving_softirq - Are we currently processing softirq?
  88  */
  89 #define in_irq()                (hardirq_count())
  90 #define in_softirq()            (softirq_count())
  91 #define in_interrupt()          (irq_count())
  92 #define in_serving_softirq()    (softirq_count() & SOFTIRQ_OFFSET)
  93
  94 /*
  95  * Are we in NMI context?
  96  */
  97 #define in_nmi()        (preempt_count() & NMI_MASK)
  98
  99 #if defined(CONFIG_PREEMPT) && defined(CONFIG_BKL)
 100 # define PREEMPT_INATOMIC_BASE kernel_locked()
 101 #else
 102 # define PREEMPT_INATOMIC_BASE 0
 103 #endif
 104
 105 #if defined(CONFIG_PREEMPT)
 106 # define PREEMPT_CHECK_OFFSET 1
 107 #else
 108 # define PREEMPT_CHECK_OFFSET 0
 109 #endif
 110
 111 /*
 112  * Are we running in atomic context?  WARNING: this macro cannot
 113  * always detect atomic context; in particular, it cannot know about
 114  * held spinlocks in non-preemptible kernels.  Thus it should not be
 115  * used in the general case to determine whether sleeping is possible.
 116  * Do not use in_atomic() in driver code.
 117  */
 118 #define in_atomic()     ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_INATOMIC_BASE)
 119
 120 /*
 121  * Check whether we were atomic before we did preempt_disable():
 122  * (used by the scheduler, *after* releasing the kernel lock)
 123  */
 124 #define in_atomic_preempt_off() \
 125                 ((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
 126
 127 #ifdef CONFIG_PREEMPT
 128 # define preemptible()  (preempt_count() == 0 && !irqs_disabled())
 129 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 130 #else
 131 # define preemptible()  0
 132 # define IRQ_EXIT_OFFSET HARDIRQ_OFFSET
 133 #endif
 134
 135 #if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
 136 extern void synchronize_irq(unsigned int irq);
 137 #else
 138 # define synchronize_irq(irq)   barrier()
 139 #endif
 140
 141 struct task_struct;
 142
 143 #if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
 144 static inline void account_system_vtime(struct task_struct *tsk)
 145 {
 146 }
 147 #else
 148 extern void account_system_vtime(struct task_struct *tsk);
 149 #endif
 150
 151 #if defined(CONFIG_NO_HZ)
 152 #if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
 153 extern void rcu_enter_nohz(void);
 154 extern void rcu_exit_nohz(void);
 155
 156 static inline void rcu_irq_enter(void)
 157 {
 158         rcu_exit_nohz();
 159 }
 160
 161 static inline void rcu_irq_exit(void)
 162 {
 163         rcu_enter_nohz();
 164 }
 165
 166 static inline void rcu_nmi_enter(void)
 167 {
 168 }
 169
 170 static inline void rcu_nmi_exit(void)
 171 {
 172 }
 173
 174 #else
 175 extern void rcu_irq_enter(void);
 176 extern void rcu_irq_exit(void);
 177 extern void rcu_nmi_enter(void);
 178 extern void rcu_nmi_exit(void);
 179 #endif
 180 #else
 181 # define rcu_irq_enter() do { } while (0)
 182 # define rcu_irq_exit() do { } while (0)
 183 # define rcu_nmi_enter() do { } while (0)
 184 # define rcu_nmi_exit() do { } while (0)
 185 #endif /* #if defined(CONFIG_NO_HZ) */
 186
 187 /*
 188  * It is safe to do non-atomic ops on ->hardirq_context,
 189  * because NMI handlers may not preempt and the ops are
 190  * always balanced, so the interrupted value of ->hardirq_context
 191  * will always be restored.
 192  */
 193 #define __irq_enter()                                   \
 194         do {                                            \
 195                 account_system_vtime(current);          \
 196                 add_preempt_count(HARDIRQ_OFFSET);      \
 197                 trace_hardirq_enter();                  \
 198         } while (0)
 199
 200 /*
 201  * Enter irq context (on NO_HZ, update jiffies):
 202  */
 203 extern void irq_enter(void);
 204
 205 /*
 206  * Exit irq context without processing softirqs:
 207  */
 208 #define __irq_exit()                                    \
 209         do {                                            \
 210                 trace_hardirq_exit();                   \
 211                 account_system_vtime(current);          \
 212                 sub_preempt_count(HARDIRQ_OFFSET);      \
 213         } while (0)
 214
 215 /*
 216  * Exit irq context and process softirqs if needed:
 217  */
 218 extern void irq_exit(void);
 219
 220 #define nmi_enter()                                             \
 221         do {                                                    \
 222                 ftrace_nmi_enter();                             \
 223                 BUG_ON(in_nmi());                               \
 224                 add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 225                 lockdep_off();                                  \
 226                 rcu_nmi_enter();                                \
 227                 trace_hardirq_enter();                          \
 228         } while (0)
 229
 230 #define nmi_exit()                                              \
 231         do {                                                    \
 232                 trace_hardirq_exit();                           \
 233                 rcu_nmi_exit();                                 \
 234                 lockdep_on();                                   \
 235                 BUG_ON(!in_nmi());                              \
 236                 sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
 237                 ftrace_nmi_exit();                              \
 238         } while (0)
 239
 240 #endif /* LINUX_HARDIRQ_H */